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WORKSHOP 95 PRAGUE, JANUARY 23-26, 1995

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PART III.

Electronics & Optics - Environment & Its Creation - Architecture, Urbanism & Visual Arts - Reliability - Production Systems & Technology - Nuclear Engineering - Transport Engineering - Development of Study - Economics & Business Activities

CZECH TECHNICAL UNIVERSITY IN PRAGUE

&

TECHNICAL UNIVERSITY IN BRNO

WORKSHOP 95 PRAGUE, JANUARY 23-26,1995

PART III.

Electronics St Optics - Environment & Its Creation - Architecture, Urbanism St Visual Arts - Reliability - Production Systems & Technology - Nuclear Engineering - Transport Engineering - Development of Study - Economics Si Business Activities

These are the Proceedings of the Fourth Annual university-wide seminar WORKSHOP % which will take place at the Czech Technical University in Prague from 23-26 January, 1996.

The aim of the seminar is to present and discuss the latest results obtained by researchers especially at the Czech Technical University in Prague, Technical University in Brno and at collaborating institutions.

The organizing committee has selected a total of more than 420 contributions divided into 21 different areas of interest.

The program for WORKSHOP 95 consists of an introductory plenary session followed by four concurrent sessions: А, В, С and D,

Part III has contributions in the areas of:

• electronics & optics

• biomedical engineering • environment & its creation

• architecture, urbanism & visual arts

• reliability • production systems & technology

• nuclear engineering • transport engineering • development of study • economics & business activities

Organizing committee:

Chairman: V. Weiss Co-chairman: J. Jan Members: M. Vrbová, J. Cihlář, M. Král, P. Hazdra, M. Kálal, F. Kasička,

F. Lehovec, D. Makovička, M. Liška, J. Matoušek, A. Strejc

Prague, December 199J,

This book was prepared with IATgX from the input files supplied by the authors. All partial articles were prepared with W95 - a special-purpose software. Programming the W95, general style and final composition of this book is by A. Strejc (CTU Computing Centre).

Published by the Czech Technical University in Prague. Printed by CTU Publishing House. Unsalable publication.

WORKSHOP 95 CONTENTS

CONTENTS 12. ELECTRONICS & OPTICS

LASER DIODE SOURCES, RESEARCH AND DEVELOPMENT 627 P. Hříbek, 0. Ре/г, I. Richter

Nd:YAG LASER TUNABLE AT 1.36-1.44 /mi SPECTRAL REGION 629 V, Kvbcček, M. Tesař, И. Jelínková, K. Hamal

PLANAR AND CHANNEL LITHIUM NIOBÁTE WAVEGUIDES FABRICATED USING ADIPIC ACID 631 J. Schriifel, J. Hradilová, P, Kolářová, Z, Burian

MODERN ELEMENTS FOR MODULAR DESIGN OF INSTRUMENTS 633 J. Bernard, F. Kopřiva, P, Tax, P. Sobotka, К. Sludenovskjj

LIFETIME CONTROL BY ENERGY-DISPERSED ION IRRADIATION 635 P. Hazdra, J, Vobecký, F. Spurný

LIMITING EFFICIENCY OF SELF-ORGANIZED SECOND-HARMONIC GENERATION IN DOPED-GLASS FIBERS BY SELF-SATURATION 637 P. Chmela, J. Pctráčck

OPTICAL FIBER DIAGNOSTICS 639 O. Samek

LASER TWEEZERS 641 M. Liška A SHEARING INTERFEROMETRY METHOD FOR DETERMINING THE STATISTICAL QUANTITIES OF RANDOMLY ROUGH SURFACES 643 M. Ohlídal, I. Ohlídal

LATTICE AND SHAPE AMPLITUDES Щ J. Komrska

THE RIGOROUS ANALYSIS OF THE QUANTUM ELECTRON WAVEGUIDES .. . 647 F. Urban, F. Matějka, R. Redhammer

A MEASUREMENT OF SURFACE ROUGHNESS BY ANGLE SPECKLE CORRELATION 649 M. Ohlídal, J. Honec MEASUREMENT, PROCESSING AND EVALUATION OF EXPERIMENTAL PROCESSES 651 L. Bejcek

AN IMPROVEMENT OF THE OPTICAL INTERFEROMETRY FOR EI1L STUDY ' 653 M. Hartl, I. Křupka

615


SYSTEM FOR THE MEASUREMENT OF THE BORE TEMPERATURE PROFILE 655 Л/. Satorie, J. Vedral

SINGLE CRYSTAL SCINTILLATION DETECTORS FOR LOW VOLTAGE AND LOW VACUUM SCANNING ELECTRON MICROSCOPY 657 /?. Autrala, J. Jirák, J. Špinka

SOURCE IMAGE INFORMATION PROCESSING 659 M. Klíma, E. Košťál, P. Zahradník, P. Dvořák, Т. Gregor, V. Kolečkář, V. Jirásek, J. Kolář, P, Koti, J. Roll

NEW CONCEPT OF OPTOELECTRONIC SENSOR USING LINEAR CCD 661 ,/. Fischer, R. Šmíd

FIBRE-OPTIC FABRY-PEROT SENSOR FOR VIBRATION AND PROFILE MEASUREMENTS 663 /. Panlicka, V. Sochor, J, Slulpa

13. BIOMEDICAL ENGINEERING

CARIES SELECTIVE ABLATION BY PULSED UV EXCIMER LASER 667 P. Gavrilov, A. Jančárek, M. Kozlová, P. Zima, M.D.

LASER-INDUCED FLUORESCENCE OF HUMAN BLOOD 669 P. Šurý, P. Poušek, M. Vrbová

EnYAG LASER FOR OPHTIIALMO-SURGERY 671 //. Jelínkova, J. Pasta, K. Hamal

ACOUSTIC RESPONSE MEASUREMENTS OF HUMAN CENTRAL AIRWAYS....673 Z. Škvor, F. Kadlec, K. Šnajdr

FORMALIZED RESTORATION AND ANALYSIS OF BIOMEDICAL IMAGE DATA 675 J. Jan, P. Kiliav

MEASUREMENTS OF SOLID PARTICLES FLOW 677 A*. Zehmda, P. Benes

IMPEDANCE TOMOGRAPHY 67!) J. Vašina, J. Lcpka, T. Macho

PHOTOELASTIC INVESTIGATION OF THE EFFIiCT OF TOOTH SPLINTING ON DURABILITY OF A SET OF TEETH 681 M. Čenský, D. Jandeková, P. Fajinan, P. Konvalinka, В. Patzák

APPLICATION OF TACTILE SENSOR CARPET FOR PRESSURE DISTRIBUTION MEASUREMENT 683 J. Volf, S. Holý

616


MECHANICAL PROPERTIES OF SELECTED BIOLOGICAL STRUCTURES 685 S, Holý, J, Kovanda, J. Stingl OPTIMIZATION OF PROSTHESIS OF CROSS LIGAMENTS OF A KNEE JOINT 687 V. Stejskal, M. Valášek, Z. Plačkova, M. Kasahara

HEMODYNAMIC RESEARCH BY ELECTRICAL BIOIMPEDANCE (EBI) METHODS 689 /. Uhlir, B. Sramck, J. Tichy, S. Trojan, M. Hojerova, J. Bendi, A. Parízek, M. Preisler, M. Uhlirova RESEARCH OF THE HEMODYNAMICS BY USING OF THE ELECTRO-IMPEDANCES METHODS 691 /. Uhlir, B. Sramtk, J. Valenta, V. Pražma, S. Papežova, J. Chyšky, P. Charval ADAPTATION OF THE CORTICAL FEMORAL BONE DUE TO THE EXTERNAL LOAD 693 M. Pctrtýl, J. Ileřt, P. Fiala, li. Vondrová, В. Czesaná APPLICATION OF SEMI-RIGID CARBON-FIBRE-REINFORCED PLATES FOR FIXATION OF HUMAN FRACTURES 695 S. Konvičková, M. Sochor THE DEVELOPMENT OF GRADIENT COATINGS SiNx BY IBAD METHOD FOR IMPROVING PROPERTIES OF METAL BIOIMPLANTS 697 S. Konvičková, F. Ccrný, R. Valenta, I. h'vnsnicka, P. Zuna, J. Michaf.ec, V. llnatowicz, P. Svoboda

THE RESEARCH ON CARDIOVASCULAR MECHANICS 699 J. Michalec, J. Valenta, S. Konvičko od, J. Řezníček

ELECTROMEGNETIC EXPOSURE OF MOBILE-TELEPHONE USERS 701 J. Vokurka, J. Vrba, Z. Škvor, R. Dlouhý

APPLICATORS FOR PIIOTODYNAMIC THERAPY 703' K. Novotný, J. Vrba

SIMULATION OF COMPARTMENTAL MODELS OF NEURONS 705 D. Suta CLOSE RANGE PIIOTOGRAMMETRY AND DIGITAL ELEVATION MODEL IN SPECIAL PURPOSES 70? /\'. Pavelka

» NEW MAGNETIC MATERIALS FOR MEASUREMENT TECHNOLOGY 709 /'. Ripka, l\. Draxler, P. Kašpar, J. Roztočil, R. Kasal

14. E N V I R O N M E N T & ITS C R E A T I O N

MODEL OF NATIONAL INFORMATION SYSTEM OF THE ENVIRONMENT . . . . 713 J. Kolář

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SAMPLING PROBE FOR MEASURING OF CLASSIFIED EMISSION 715 J. Нететка, L. Mares

SETUP FOR MONITORING OF A RESPIRABLE AEROSOL 717 J, Král, J. Voltr

APPLICATION OF RADIOANALYTICAL METHODS FOR ENVIRONMENTAL MONITORING 719 I. Musilek, T. C'echdk, J. Král, H. Th. Wolterbeek, P. Kuik

CONTAMINATION OF SEDIMENTS BY URBAN STORM DRAINAGE 721 Z. Handová, M, Liško.

HYDRODYNAMIC TOOLS FOR RIVER CATCHMENT ANALYSIS 723 P. Ingeduld, E. Zeman, S. Vaněček

SIMULATION MODELS OF TRANSPORT PROCESSES IN A WATERSHED 725 T. Dostal, J. Vaška, K. Vrana

IMPROVEMENTS OF RATING CURVES USED IN HYDROLOGY BY APPLICATION OF MATHEMATICAL MODELS 727 J. Špalka, E. Zeman

MODELLING OF CONTAMINANTS MIGRATION IN THE REAL BODY USING A MODIFIED ID MODEL 729 D. Vopálka, K. Štamberg

STUDY OF DISPERSION PROCESS IN A BED OF SEDIMENT 731 A'. Štamberg, J. Škrkal, D. Vopálka

MULTICOMPONENT EQUILIBRIUM SORPTION MODELS 733 A'. Štamberg, P. Beneš, D. Vopálka, l\. Chalupská

DIFFUSION AND SORPTION OF TRACE ELEMENTS AND RADIONUCLIDES IN SOILS 735 A. Gosman, L. Pětková, L. Šustrová, N. Kosatková

INTERACTION OF TRACE ELEMENTS WITH IIUiMIC SUBSTANCES AND ITS EFFECT ON THE ADSORPTION ON CLAYS 737 Л*. Kratzer, P. Beneš, J. Mizera, H. Kyzeková

MEASURING THE MATERIAL PARAMETERS OF RADIOACTIVELY CONTAMINATED WATER IN THE ROŽNÁ WASTE DISPOSAL SITE 739 J. Toman, V. Havlík, O. Hrstka, R. Černý

STUDY OF THE SHORT TERM FLUCTUATUION OF WATER CONSUMPTION 741 L. Macek, P. Zykan

HYDRODYNAMICS AND STABILITY IN ENVIRONMENTALLY ACCEPTABLE CHANNELS 743 K. Mareš, l. Bémová, I. Marešová, J. Vodsloň ч

618


IMPROVEMENT OF WATER QUALITY IN RIVERS BY AERATION AT HYDRAULIC STRUCTURES 745 P, Gabriel, J. Doleček STABILIZATION OF SOLID WASTES FROM THERMAL POWER STATION BY CALCIUM CARBIDE LIME 747 S, Modrý, J. Janata

STABILIZATION OF Cd WASTES 749 A. Grunwald, li. Poupová, L. Svoboda

RECYCLING OF SOLID CHROME TANNED LEATHER WASTES 751 D. Janáčová ACOUSTIC PROPERTIES OF THE POLYMER AND RUBBER WASTE ELEM ENTS 753 M. Vaňková, M. Dolozílek, A. Ryndová, li. Grycová, S. Vašut

ASPECTS OF THE INDOOR ENVIRONMENT 755 J. Kočí, ./. J um jda THE EVALUATION OF THERMAL-HUMIDITY MICROCLIMATE IN CLASSROOMS OF THE ELEMENTARY SCHOOLS 757 D. Cuprovti COMPARISON OF MICROCLIMATE VALUES MEASURED BY THE MEASURING SET 'NOBAVI' AND THE MEASURING PLANT 759 L. Novák, D. Cuprová, A. Navrátilová, V. Božek

SUGGESTION FOR INTERIOR ARRANGEMENT TO OPTIMIZE DAYLIGHT ILLUMINATION OF THE CLASSROOMS 761 Л'. Cupr

STUDY OF THE SHORT TERM FLUCTUATUION OF WATER CONSUMPTION 763 L. Macek, P. Zykan

15. ARCHITECTURE, URBANISM & VISUAL ARTS

AIRBORNE RADON CONCENTRATION AND DOSE RATE IN THE PRAGUE METRO 765 J. Sabol

WORK IN THE OPEN AIR IN FRANCE AND ITALY 769 Jiří Sobotka

INTERNATIONAL SUMMER SCULPTURAL WORKSHOP AT ORLÍK CASTLE 771 Vladimír Preclík

PRESENTATION (INSTALLATION — ACTION) 773 Tomáš Ruller

619


THE ANALYSIS OF THE NAVE VAULTS IN THE CHURCH OF OUR LADY'S ASSUMPTION IN NOVA РАКА AND ST KLARA'S CHAPEL IN CHEB 775 M. Pavlík, P. Dvořáček

PRESERVATION AND NEW FUNCTIONAL USE OF INDUSTRIAL HERITAGE 777 //, Zemánkova THE CONCEPTION OF TEACHING "THE STRATEGY FOR DEVELOPMENT OF TOWNS AND REGIONS" 779 A. Mansfeldová

VILLAGE RENEWAL: URBAN AND ARCHITECTURAL ASPECTS 781 M. Martinek, J, Kozel

THE RELATION OF THE URBAN SPATIAL STRUCTURE AND THE TRAFFIC NETWORK OF BIG CITIES 783 J. Gřegorčík, J. Pavliček, M. Konvička, G. Kopáčik, Л'. Pazourek, D. Wendscheová REGIONAL PLAN OF CONCEPTION OF INTEGRATION OF SOUTH MORAVIAN AND LOWER AUSTRIAN BORDER REGIONS 785 M. Kyselka, J. Kratochvíl

PROJECT HANDICAP 787 J, Sindlar, J. Halabala, P. Flerzanovd, P. Zalmanová

INTENSIFICATION OF URBAN NETWORKS 789 P. Srytr and coworkers

THE NEW USAGE OF MINING OBJECTS IN THE OSTRAVA-KARVINA AGGLOMERATION 791 M. Matej

EDUCATION OF PLANNING PROFESSIONALS 793 K. Maier, K. Vlcek, P. Rohon, J. Riha, J. Štipek

16. RELIABILITY

STATISTICAL APPROACH TO MODEL UNCERTAINTIES 797 M. Holický, M. Vorlíček

PROBABILITY BASED ASSESSMENT OF SERVICE LIFE 799 M. Holický

ADVANCED METHODS IN DRAFTING STRUCTURAL CODES 801 A. Florian

AMENDMENT OF THE CSN 73 6209 LOADING TESTS OF BRIDGES 803 M. Studničková

620


RELIABILITY-BASED DESIGN OF COMPOSITES 805 A. Fcraidon, J. Šcjnoha THE EFFECTS OF PERFORATIONS IN CLAY UNITS ON MASONRY STRENGTH 807 D. Pume

ANALYSIS OF SEISMIC LOADING OF TANK T 1500 (NH3) 809 F. Čermák VERIFICATION OF BRIDGE RECONSTRUCTION BY MEANS OF WIRE STRAIN GAUGES 811 V. Hrdoušek, V. Kukaň, J. Záruba

SENSITIVITY AND PROBABILISTIC ANALYSES OF CHARLES BRIDGE 813 J. Žák, D. Novák

ASSESSMENT OF WALL PANEL BUILDINGS 815 F. Čermák, V. Moucha, D. Рите, S. Modrý, M. Eliášová, J. Chmel

RESONANT PRESSURE SENSOR 817 К. Draxler, F. Mazánek, J. Věříš

C-V PROFILING ON HETEROJUNCTION SYSTEM 819 P. Sichrovský

REINFORCED GRASS APPLICATION FOR EMERGENCY SPILLWAYS 821 L. Satrapa, V. Broza

17. PRODUCTION SYSTEMS & TECHNOLOGY

MATHEMATICAL MODELLING OF THE INJECTION MECHANISMS OF THE DIE CASTING MACHINES S25 P. Vávra, P. Sýkora T 7, COMPUTER UTILIZATION IN DESIGN OF THE DIE CLOSING UNIT OF DIECASTING MACHINES 827 S. Maňas, M. Hladík, Т. Vampola

INCREASING OF FORMING MACHINE PRODUCTIVITY 829 B. Rudolf, V. Sefrna

OPTIMIZATION OF A CUTTING PATH 831 G. Dohnal SYSTEM FOR PRODUCTION OF GEOMETRICALLY COMPLICATED SURFACES IN FLOW MACHINES 833 J. Rybin, J. Neústupa, Т. Curda

RESEARCH ON NEW CUTTING FLUIDS 835 J. Mádl

621


APPLICATION OF PSD IN ROBOTICS 837 R. Malik, P. Goiula

ULTRASONIC SCANNING SYSTEM FOR MOBILE ROBOTS 839 V, Oplušlil, D. Svačina

TESTING THE QUALITY 841 A. Fiala, L. Hobsl, etc. ELABORATION OF METHOD FOR EVALUATION OF SHEET-METAL FORMABILITY 843 R. Cada, S. Rusz EXAMINATION OF DIFFERENT MATERIALS PROPERTIES IN METAL FORMING 845 L. Janíček, L. Kolařík, II. Hudec, J. Pclruěka

18. NUCLEAR ENGINEERING

ACCELERATOR DRIVEN REACTORS 849 J. Zeman, K. Tuček MODULAR SYSTEM OF EDUCATIONAL COMPUTER PROGRAMS "ENERGY SOURCES OF THE EARTH" 851 D. Hcfmanshj SOFTWARE RELIABILITY ASPECTS IN DIGITAL CONTROL SYSTEMS OF NUCLEAR REACTORS S53 K. Matějka, M. Kropík, T. Sejba

INCREAS IN THE MAXIMUM POWER OF THE REACTOR VR-1 VRABEC S55 К. Matějka, A. h'olros, S. Kropš, l]. Sklenka, Т. Šejba BOILING SIMULATION BY PRESSURE AIR BUBBLES IN THE CORE OF TRAINING REACTOR VR-1 857 5. Kropš, L. Sklenka DETERMINATION OF THE EFFECTIVE NEUTRON TEMPERATURE IN THE CORE OF THE TRAINING REACTOR VR-1 VRABEC 859 V. Babulska, A. Kolros, K. Matějka TREATMENT OF SPENT COMPOSITE ION-EXCHANGERS FOR FINAL DISPOSAL 861 ' F. Šebcsla, J. John, A. Moll, J. Sic

19. TRANSPORT ENGINEERING

METHODOLOGY AND DESIGN OF HIGH RELIABLE TRANSPORTATION SYSTEMS 865 P. Moos, ,/. Vlček

622


SUPPORT OF TRANSPORTATION MANAGEMENT BY INFORMATION SYSTEMS 867 P. Moos

DISTRIBUTED MONITORING AND ROAD TRAFFIC CONTROL 869 P. Moos, L. Lholská, M. Vlček

TRANSPORT MODEL OF OVERSEAS COAL S71 B. Duchoň, M. Ilobza

THEORETICAL MODEL FOR TRAFFIC VOLUME 873 Л/. Hála, P. Karlkký

IMPROVEMENT OF RELIABILITY AND SECURITY OF ROADS 875 F. Lehovec, P. Karličky, J, Vol}, F. Luxcmburk, P. Jirava, L. Vcbr, P. Slaby, M. Feill THE POSSIBILITY FOR MORE PRECISE COMPUTATIONS OF ONE DAY TRAFFIC VOLUME FROM SHORT-TERM MEASUREMENTS S77 P. Karličky, Г. Vacek, M. Hála FATIGUE STRENGTH MODELLING AND ITS CONSEQUENCES FOR PAVEMENT DESIGN S79 J. Vol/ NEW POSSIBILITIES FOR MODIFICATION OF ASPHALT BINDERS AND MIXES S81 F. Luxemburk, D. Klobouček PHOTOGRAMMETRIC SURVEYING OF CONSTRUCTION OBJECTS' DEFORMATIONS 8S3 P. Dvořáček

MEASUREMENTS OF THE STRUCTURES OF THE CARRIAGEWAY SS5 J. Sýkora

20. DEVELOPMENT OF STUDY

ECOTECHNOLOGY — A NEW STUDY BRANCH AT THE FACULTY OF MECHANICAL ENGINEERING, CTU SS9 F. Drkal DEVELOPMENT PROJECTS IN COMPUTER SUPPORTED EDUCATION OF PHYSICAL ENGINEERING S91 L. Drška, R. Liška, M. Šiňor, J. Vondráček FIRST COURSE ON TRUSTED TELEINFORMATIC SYSTEMS AT FEE CTU IN PRAGUE 893 J. Přibyl

COURSE OF NOISE CONTROL 895 Я. Novy

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WORKSHOP Об CONTENTS

PROJECT OF Л CONTINUING EDUCATION COURSE ON "AIR POLLUTION CONTROL" 897 J, Ilcmcrka

PRACTICAL FORMS OF EMC EDUCATION 800 J. Svačina, J. Soltldn

NEW MULTIMEDIA WORKPLACES 901 J, Svoboda, В, Simák, T. Zeman, M, Vandrdk, Р. Иурй, М. Hrud A COMPLEX DIDACTIC SUPPORT OF GIS EDUCATION AT THE CTU PRAGUE 903 M. Iluml

21. ECONOMICS & BUSINESS ACTIVITIES

DEVELOPMENT OF CITIES AND REGIONS 907 V. Bcran SOME CONSEQUENCES OF PRESENT HOUSING POLICY IN THE CZECH REPUBLIC 900 M, Plachky

RECOVERING FINANCING IN CZECH REPUBLIC 911 F, Freiberg

INTERACTIVE SIMULATION MODELS AS A TECHNIQUE FOR RISK CALCULATION 913 V. Dcran

ABSORPTION OR VARIABLE COSTING METHODS? 915 K. Macík COST-VOLUME-PROFIT ANALYSIS (BREAK-EVEN ANALYSIS) UNDER RISK 917 M. Písek

APPLICATIONS FEATURES OF THE HOUR OVERHEAD TARIFFS METHOD...919 M. Zralý MODELS AND SOFTWARE FOR MANAGEMENT OF PRODUCTION IN THE CONSTRUCTION INDUSTRY 921 J. h'lvafm, A. Junek, A, h'acaba, J. Kučerová, D. Vytlačil, M. Sura CHANGES IN THE VOLUME AND STRUCTURE OF INCOMES UNDER ECONOMIC TRANSFORMATION IN THE CZECH REPUBLIC 923 //. Pačesová

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Section 12

ELECTRONICS

&

OPTICS

WORKSHOP Об ELECTRONICS & OPTICS

LASER DIODE SOURCES, RESEARCH AND DEVELOPMENT

P. Hříbek, O. Petr, I. Richter

CTU, Рас of Nucl. Sci. & Phys. Eiig., Ocpt. of Physical Electronics V Holešovičkách 2, 180 00 Praha 8

Key words: laser, laser diode, medical applications

Lasers are attractive sources for the order of potential applications including optical communications, medicine, remote sensing, radars, industrial applications. Solid state lasers arc an attractive source for these applications. In the past they were optically pumped by discharge lamps. II led to their low laser efficiency and so to their small extension into these fields. Major breakthroughs in losing efficiency in recent years brought semiconductor laser diodes and laser diode arrays.

Laser diodes arc very efficient, long lived, and power-stable sources of coherent radiation, the wavelength of which can be selected to lie within the strong absorption band of solid state lasing ions. It makes it possible to develop efficient powerful lasers with several laser diodes coupled into one powerful beam, and with efficiency up to 40% or develop laser-diode-puinped rod solid state lasers with up to 50% for slope efficiency, and as well efficient diode pumped waveguide lasers.

Laser diodes provide dramatic improvements of the lasers not only in laser efficiency but in the lifetime, instrument size, and other important instrument characteristics. Their applications carry appreciable extension of lasers into communications, medicine, consumer's goods, and different areas of industry.

Our interest had been concerned to the development of diagnostic systems for laser diode parameters characterization, design and development of powerful diode laser sources for medical use and laser-diode-pumped solid state lasers, and the possibility to control parameters of laser diode sources by nonlinear optics methods.

A diagnostic system for laser diode parameters characterization was developed and methodology of laser diode parameters measurement elaborated. Stabilized CW 0.5 W laser diode source had been realized at 810 nm for medical applications, and for selective pumping of bulk and waveguide solid state lasers. Laser output characteristics as power stability and frequency stability will be discussed. The use of nonlinear optical effects such as self-organised nonlinear optical effects in photorefractive materials for laser diode line-width narrowing, and phase-locking of laser diode arrays is proposed. Results of the two different applications of the developed CW 0.5 W laser diode source are shown. First is the study of the influence of laser radiation on the skin of the human body in medicine laser dermatology during therapy [1]. Second is the frequency stabilized narrow band light source for NchYAG laser axial pumping.

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WORKSHOP 95 ELECTRONICS & OPTICS

References:

[1] Application of laser radiation in biophysics, FRVS grant No. 1142102.

This research has been conducted at the Depart nenl of Physical electronics us part of the research project "Modern laser sources for medical and optical communications" and has been supported by CTU grant No. 0488206.

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WORKSHOP 95 ELECTRONICS Se OPTICS

Nd:YAG LASER TUNABLE AT 1.35-1.44 /Ш1 SPECTRAL REGION

V. Kubeček, M. Tesař, H. Jelínková, K. Hamal

CTU, Рас. of Nucl. Sci. & Phys. Eng., Dcpt. of Physical Electronics V Holešovičkách 2, 180 00 Praha 8

Key words: Nd:YAG, tunable laser, eye-safe wavelength

The Nd:YAG laser is a well developed and well proven technology. It is known that laser emission in NchYAG can be achieved on different transitions in the лР3/2 to ''/9/2, ''/ц/г and '/i3/2 manifolds [1]. It has been particularly demonstrated that pulsed operation of the Nd:YAG laser is possible with good efficiency at 1.44 /im wavelength. This wavelength is interesting for atmospheric propagation and medical applications because it is eye safe and coincides with absorption peak of water in this spectral region. It has been shown that the same effects on tissue can be obtained with 1.44 /im Nd:YAG laser as with 2.12 /im Ho:YAG laser. For technical reasons, the power output and pulse repetition rates from many holmium lasers arc limited. Thus, an alternative laser that provides similar tissue effects but more flexibility in laser parameters would be advantageous.

We have developed a new Nd:YAG laser with selectable wavelength either at 1.06 or 1.44/im, Average output power is 16.8 W at 1.06/tm or 4.8 W at 1.44 цт [2]. The linear laser resonator consists of a flat output mirror M3 and two spherical rear mirrors Ml, M2 with shutter S between them [3]. As an active medium a Nd:YAG rod is used. When shutter S is closed oscillations at 1.44/mi between mirrors M2 and M3 take place while when the shutter is open, the stronger line at 1.064 /zm oscillates between mirrors Ml and M3 quenching generation at the weaker line at 1,44/tm, The advantage of a such laser for medical applications is the possibility of selection of wavelength with more favourable absorption coefficient in tissue, according to the desired application.

Under special, conditions it was also possible to generate both wavelengths simultaneously. The ratio of the output energy at one wavelength to energy at the second wavelength is strongly dependent on laser repetition rate.

By inserting a prism P into the resonator the laser became tunable. By tilting the mirrors it was possible to obtain oscillations either at 1.356/im, 1.414 /nn or 1.443/im. The strongest line was at 1.35/*m with output power of 4 W at repetition rate of 10 Hz, while the weakest line was 1.41/гт (1.7 W). The output power at 1.44 /zm was 2.7 W. basing at 1.43/nn was not observed. Q-switching at 1.35 /im and 1.44/nn has been achieved using either acoustooptical or electrooptical Q-switch and giant pulses 80 ns long with energy of 50 mJ were generated which indicates possible application of such a laser in optical ranging and similar applications.

The first experiments showing medical applicability of the developed dual wavelength free running NchYAG laser combined with fibre optics beam delivery system, have been successfully performed for endodontic procedures in stomatology [4] and the study of other applications is carried out.

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WORKSHOP 95 ELECTRONICS к OPTICS

In conclusion, the important fact confirming attraction of the presented results is the possible development of compact, all solid stale Nd:YAG lasers operating in this spectral region. This has been demonstrated recently by the first operation of the Nd:YAG laser at 1.443/<m pumped by continuous laser diode [5].

References: (Ij MARLING, J.: 1.05 - 1.Ц \tm Tunability and Performance of the CW Nd:YAG Laser.

IEEE J. Quantum Electron. Vol. QE-14, (1978) 56-62. [2] KUBECEK, V. - JELÍNKOVA, II. - HAMAL, К. - ZANZOTTBRA, E.: Dual Wave

length LU/1M /tin Nd:YAG Laser for Medicine, CLEO/EUROPli 1994 conference Amsterdam, paper CVVF24.

[3] HAMAL, К. - MAREK, J. - KVAPIL, J. - SKODA, V.: Combined 1.00/1.32 urn Nd:YAG Laser for Medicine. CLEO Technical Digest, paper TUK33 (19S7) 7G.

[4] JELÍNKOVA, II. - HAMAL, К. - KUBECEK, V. - DOSTÁLOVA, Т.: Irradiation of Human Dental Tissues Using 5 Laser Wavelengths. CLEO/EUROPE 1994 conference Amsterdam, paper CWF 23.

[5] KUBECEK, V. - COUDERC, V. - BARTIIELEMY, A. - LORADOUR, P.: Laser Diode Pumped Nd.'YAG Laser Operating nl an Eye Safe Wavelength of 1.ЦЗрт. Electronics Letters (1994) — accepted for publication.

This research has been conducted at the Department of Physical Electronics as part of the research project "Dual Frequency Nd.'YAG Laser for Medicine and Ecology" and has been supported by Grant Agency of the Czech Republic grant No. 102/93/074.

630

WORKSHOP m ELECTRONICS St OPTICS

PLANAR AND CHANNEL LITHIUM NIOBÁTE WAVEGUIDES FABRICATED

USING ADIPIC ACID

J. Schrofel, J. Hradilová*, P. Kolářová*, Z. Burian

CTU, Fac. of Electrical Eng., Dcpt. of Microelectronics Technická 2, 166 27 Praha б

^Institute of Chemical Technology Prague, Dept. of Inorganic Chemistry Technická 5, 16(5 28 Prague

Key words: integrated optics, planar waveguides, channel waveguides, proton exchange, annealed proton exchange, lithium niobáte, aclipic acid

In optical communications and sensor and measurement techniques a lot of components based on channel waveguides structures can be utilized. Their propagalive properties, i.e the number of guided modes at a given wavelength, should be precisely specified. The commonly used method of fabrication of the waveguides depends on the diffusion of Ti atoms in to LiNb03 single crystal substrates, which results in obtaining the waveguides of a small depth (with two modes maximally). The fabrication of waveguides of the desired parameters is very difficult to reach by using this method. These inconvenient factors may be profoundly excluded, if fabrication of the waveguides is carried out by the proton - exchange method. During this process, a part of Li atoms is exchanged by hydrogen atoms. As a result of decreasing the concentration of Li titoms in respect to that of Nb atoms, an increase in the value of extraordinary refraction index (ne) is observed in the area of processing.

Z- and X- cuts lithium niobáte substrates were thoroughly prccleaned using various organic solvents and were preheated before immersing, them into the molten adipic acid. Adipic acid, either pure or lithium doped, was contained in a quartz crucible, passed into a tightly closed glass vessel and maintained at the set temperature for proton exchange. Then the substrates were washed by distilled water and ethanol and passed in a platinum crucible into a laboratory oven for annealing. Diffusion temperatures and times ranged from 175°C to 230°C and 30 minutes to 12 hours, resp. Annealing temperatures and times ranged from 350°C to 520°C and 30 minutes to «I hours. TM and ТЕ modes effective indices of the APE waveguides were measured by the standard prism coupling technique with futile prism at 0.633 /im wavelength.

The propagation properties of APE (i.e. annealed proton exchanged) LiNb03 waveguides depend on several technological factors: the proton exchange and annealing temperatures, the time of their duration , composition of reaction media and crystal orientation of the substrates. For channel waveguides also mask openings are very important parameters.

The methods of fabrication of some planar and channel waveguides in the Z- and X- cut LiNbOa substrates are presented here by using non-toxic and save-to-use protonic source •— the adipic acid, either pure or lithium doped.

631

WORKSHOP 95 _. ELECTRONICS & OPTICS

Typical experimental conditions for fabrication of 3-4 modes planar waveguides with Дпе = 0.22-0.43 as follows (PE proton exchange, A annealing):

for X-ciit: time PE 30 min time A 30 min temperature PE 213°C temperature A 375°C protonic source: adipic acid with 0.5moI/% lithium aclipntc

or time PE 30 min time A 90 min temperature PE 213°C temperature A 350°C protonic source: pure adipic acid

for Z-cut: time PE 75 min time A 90 min temperature PE 213°C temperature A 350°O protonic source: pure adipic acid

Single-mode channel waveguide in Z-cut LiNb03 was prepared with the following experimental conditions:

time PE 30 min time A GO min temperature PE 213°C temperature A 350°С opening of the mask 9.25 /mi protonic source: adipic acid with 0.5 mol/% lithium adipate

Optical loss of this single-mode waveguide was 0.45dB/cm.

References: |1] CTYROKÝ, J. - HtJTTEL, I. - SCHROFEL, J. - SlMÁNKOVA, L.: Integrated Optics

Praha, SNTL 1987 (in Czech)

[2] HRADILOVA, J. - SCHROFEL, J. - CTYROKÝ, J. - J ANTA, J.: Proton exchanged LiNb03 waveguides: Preparation and properties Proc. FOTONIKA 92, Olomouc 1992, Sept. 8 - 11, pp. 215-220

This research has been conducted at the Department of Microelectronics as part of the research projed "Research of пеги materials, technologies and diagnostics of optical waveguiding structures for application in integrated optics" and has been suported by Grant Agency of dech Republic grant No. 103-93-0783

632


MODERN ELEMENTS FOR MODULAR DESIGN OF INSTRUMENTS

J. Bernard, F. Kopřiva, P. Tax, P. Sobotka, К. Studenovský

CTU, Fac. of Mechanical Eng., Dept. of Precision Mechanics & Optics Horská 3, 128 00 Praha 2

*Czcch Meteorology Institute, Laboratory of Primary Metrology V botanice 4, 150 72 Praha 5

Key words: modular design, device actuators, elastic elements, piezoceramics, optical parts

During the second stage of solving the problem, attention was paid mainly to the following modular elements.

Piezoceramic rotation system with high position accuracy. The present state of position systems developed on the basis of commonly used constructions (worm gearing, spur gearing, etc.) no complies with the requirments for their accuracy of reproduction, velocity of position, etc.

The above mentioned aspects led to the development of modern position system, that is designed for the applications using the accurate rotary drive, for example for the astronomical mounting.

Basic design parameters required for the mounting of middle-class astronomical telescopes are: accuracy of the rotation 1 second, slow rotation 1 turn/24 hours, quick rotation 1 rev./10 min.

The required design parameters led to the exploitation of a well known piezoceramic linear drive. Wc decided to use a column of ceramic plates whose orientation leads to the axial contraction of the sliding stack in dependence on the force and orientation of electric field. The maximum lift of the stack of basic length of 50 mm is about 45 m at the supply voltage of 1000 V. The lineary dependence mm/V (in fact a hysteresis curve) changes minimally independence on ambient temperature.

The characteristics of piezoceramic materials predetermine their application in variable clicmatic conditions. The catalogue linear motion of the unit is transformed to the rotation motion by a leverage mechanism. Two linear drives are placed in a monoblock gearing motions exist within the range of clastic deformation in flexible joints. The mechanism function is: the piezo-drive 1 fixes the position of the position desk ("pliers"), that is joined directly to the telescope rotation axis. Drive 2 provides tangential displacement of the disc. By means of the three monoblocks containing units 1 and 2, it is possible to ensure unidirectional rotation motion fulfilling the above mentioned requirments.

Now the functional monoblock model has been completed and its dynamic properties, rigidity and other parameters decisive for the quality of rotation drive are tested in the laboratory.

633


Miniature harmonic gearbox. Л design with added parallel friction epicyclic gear has been chosen to get a high gear ratio (from 1:500 to 1:2000). Life tests of the main deformation part (mainly of a friction gearing between the rotor and stator) have showed that wc should adapt it to decrease its stress and to achieve a longer gear box life. Experimental data correspond well with the results of the theoretical solution by classical method. We also paid attention to the selection of suitable materials and to partial changes in production technology of gearbox parts. If the diameter of the gearbox is 26 mm and the length is 27 mm, then total torque 20Nmm is reached. The efficiency of the gear is as much as 0.60.

Fast linear drive with small travel. A linear drive that uses longitudinal forces of electromagnetic field with a pulse magnetic system of a "pot type" has been used, tn spite of its small size (0-24 mm, length 30-40 mrn) comparable with piezoceramic elements, this drive enables motion up to 2.5 mm within the time interval of max. 5 ms. A method ol drive design (including software) has been devised. After the input of force distribution (0-4 N) it optimizes the shift time and possible also the repeating frequency. This drive is suitable for the use in stepping systems, shutter or valve control. We have achieved a small size drive by a special design of mechanical system for a reverse movement. During the last stage of the design, we will concentrate mainly on reliability problems and durability the key parts of the drive and also try to minimize production costs.

Optical modular elements with elastic joint of parts. When verifying an original handle of optical part, it has been found that the working modulation frequency 1000Hz (original requirement) is not possible to reach with a bigger load (above 20 N). The horizontal mounting offers a modulation frequency up to 100 Hz (load from 20 N to 25 N). The device is intended for automatic adjustment of an interferometer.

We have analyzed the influence of a circular plane deformation upon a wavcplane shape that falls on this plane. It was done as a part of the research of modular optical elements for the primary length interferometer. We have designed a method for compensation of a distorted waveplane. The aim is to pressure on the rear side of the plane. This principle is also useful in the field of adaptive optics to improve quality of laser beam.

This research has been conducted at the Department of Precision Mechanics & Optics as part of the research project "Perspective modular elements for instrumentations design" and has been supported by CTU grant No. 28122

634


LIFETIME CONTROL BY ENERGY-DISPERSED

ION IRRADIATION

P. Hazdra, J . Vobecký, F. Spurný

CTU, Рас. of Electrical Eng., Dcpt. of Microelectronics Technická 2, 166 27 Praha б

Key words: radiation defects, semiconductors, lifetime control

Nowadays, defect regions created by high-energy electrons and/or high-energy ions are widely used for lifetime control in semiconductor power devices [1, 2, 5, 6]. These conventional iiradiation techniques provide the two limit cases of the lifetime profile - homogeneous (liigb-encrgy electrons) and strongly localized (high-energy light ions) - which often cannot fulfil all designer needs. The dispersion of the ion energy within the ion beam can modify the damage profile to nearly an arbitrary distribution. This effect is promising for many applications.

Л novel irradiation technique for selective carrier lifetime control, energy-dispersed ion irradiation, is presented in this paper. The energy dispersion of the incident 1200 keV proton beam from the Van dc Graaf generator was achieved by the proton transmission/reflection on the Au-foil. Various configurations were used to change the energy window within the range of 0 to 1200 keV. Defect detection and characterization was performed using DLTS. Resulting damage profiles were compared with corresponding simulations of primary defect distributions. Results confirmed that the defect structure was identical to that observed after mono-energy proton irradiation [3, -1]. The damage (lifetime) profile can be effectively set by the magnitude of the proton energy dispersion and simulated by standard techniques.

i , , u- 1 g 1 J S I • — • — • — • — • — • — ' О 30 60 90 120 ISO Ш 0* 0.» l i 1-S 1Л

DEPTH (цп>) REVERSE RECOVERY TIME ((is)

Fig.l: The doping profile of the simulated diode and two profiles of vacancies whose influences are being compared (left); resulting Vj vs. i r r trade-off (right).

Recently, we reported on the simulation system developed for accurate simulation of the devices subjected to mono-energy low-dose proton irradiation [l]. The results achieved enable us to extend its usage to the case of proton irradiation with arbitrary energy-dispersion.

635

WORKSHOP 95 ELECTRONICS k OPTICS

To verify the impact of the multi-energy irradiation on the improvement of semiconductor tic-vice performance, we simulated [4] static and dynamic characteristics of a silicon high-power p+nn+ diode irradiated either by conventional mono-energy 3.3 MeV or by multi-energy 2.8 to 3.3 MeV proton beams. The left part of Fig.l shows the doping prolilc (holes and electrons) of the diode under study together with two profiles of primary damage (vacancies) being further compared. The right side of Fig.l shows the forward voltage drop V/ versus the reverse recovery time lTT trade-ofF of the simulated diode irradiated by mono-energy and multi-energy beams of 3.3MeV and 2.8 to 3.3MeV respectively, with the dose ranging from 0 to 1011 cm - 2 . The effort of the device designer is usually concentrated on achievement of a tTT as low as possible with conserved Vj [1-6]. It is evident that a multi-energy beam lowers trr as much as 10% for a given dose without increasing the voltage drop V/. Simultaneously, the diode soft factor S is increased as much as 10 - 14% with high doses. Thus the irradiation by means of a multi-energy proton beam provided a twofold improvement of the customary device characteristics.

A novel technique for selective lifetime control - energy-dispersed ion irradiation -was proposed. Experimental results showed that the defect structures created by mono-energetical and energy-dispersed protons are identical. Comparative simulations of the silicon diode subjected to multi- and mono-energy proton irradiations confirmed the advantages of the method proposed.

References:

[1] HAZDRA, P. - VOBECKÝ, J.: Accurate Simulation of Fast Ion Irradiated Power Devices, Solid-State Electronics, Vol. 37, No. 1, 1994, pp. 127-134

[2] VOBECKÝ, J. - HAZDRA, P. - VOVES, J. - SPURNÝ, P.: Accurate Simulation of Combined Electron and Ion Irradiated Silicon Devices for Local Lifetime Tailoring, Proc. of the 6th International Symposium on Power Semiconductor Devices and IC's, Davos, Switzerland May 31-June 2, 1994, pp. 265-270

[3] HAZDRA, P. - SPURNÝ, F. - VOBECKÝ, J.: Defects Generated by Dispersive High Energy Ion Beam, Proc. of the X International Conference on Ion Implantation Technology IIT'94, Catania, Italy, June 13-17, 1994, P-2.10

[4] HAZDRA, P. - HAŠLAR, V. - VOBECKÝ, J.: Application of Defect Related Generation Current for Low-Dose Ion Implantation Monitoring, Proc. of The X International Conference on Ion Implantation Technology IIT'94, Catania, Italy, June 13-17, 1994, P-5.22

[5] VOBECKÝ, J. - HAZDRA, P. - SPURNÝ, F.: Electron and Ion Irradiation of Silicon Devices for Lifetime Tailoring, Proceedings of the 2nd International Seminar on Power Semiconductors 94, CTU Prague, August 31-September 2, 1994, pp. 45-50

[6] HAZDRA, P. et al.: Big Hopes for Application of Radiation Damages in Semiconductor Devices, Proceedings of the CTU SEMINAR 94, Part C, 1994, pp. 181-182

This research has been conducted at the Department of Microelectronics as part of the research project "Application of High-Energy Ions on Power Device Parameter Optimization" and has been supported by CTU (TU) grant No. 38184-

636


LIMITING EFFICIENCY OF SELF--ORGANIZED SECOND-HARMONIC

GENERATION IN DOPED-GLASS FIBERS BY SELF-SATURATION

P . Chmela, J . Petráček

TU, Fac. of Mechanical Eng., Institute of Physical Engineering Technická 2, G1C 69 Brno

Key words: second-harmonic generation, self-organization, self-saturation, optical fibers

The self-saturation of self-organized second-harmonic generation (SHG) in doped glass fibers [1-3] has been predicted first by the directional photoionization model by Anderson et al. [4]. Though the directional photoionization model was found to be in a strong disagreement with the experiments on preparing optical fibers with a third exciting radiation [5,6] and it also gives wrong predictions concerning the growth rate of self-organized SHG [7,8], which is a consequence of the fact that it does not involve any memory mechanism [8], this model yields good predictions as for the saturation of the self-induced effective quadratic susceptibility Xcjj ~ hui/Iiu, Uw and I2u, being the light intensities of fundamental and second-harmonic íadiation, respectively) [8-10].

The saturation of hu/I* has been predicted by the cumulative local-response phe-nomenological model [8] as well. The saturation value of 1ъш/1% predicted by the theoretical models is approximately [4,8] (hJlDsat < 10~1Gm2/VV.

In order to verify the saturation of self-organized SHG, the values of (h^/f^sai were calculated for about ten former experiments on self-organized SHG in [10]. The calculated values range from about 0.2xl0~16 to 2xl0~16 m2/W. The uncertainty within one order of the results obtained is dominantly caused by the inaccuracy of experimental data, especially of the radiation power propagating in the liber core and the mode structure of interacting radiation. Maybe that the saturation had not been reached in some experiments considered. We are of the opinion that more careful measurements will bring a better specification of the saturation value. Anyhow, the obtained results manifest the predicted saturation of self-organized SHG clearly enough.

It seems that the self-saturation is a general feature of self-organized SIIG in doped glass. The ratio l-ijlt saturates almost at the same value being of the order 10 - I 6 m 2 /W irrespective of the light intensities of pump and second-harmonic seeding radiation, and even of the effective fiber length, which might substantially affect the further evolution of the research on self-organized nonlinear optical phenomena towards the parametric down conversion effects for example.

References: [1] ÓSTERBERG, U. - MARGULIS, W.: Experimental studies on efficient frequency dou

bling in glass optical fibers Optics Letters, 12 (1987), 57 [2] STOLEN, R. H. - TOM, H. W.: Self-organized phase matched harmonic generation in

optical fibers Optics Letters, 12 (1987), 585 ^

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WORKSHOP % ELl'XJTRONICS fc OPTICS

[3] CIIMELA, P.: Self-organized nonlinear optical phenomena in optical jihem in Modern Nonlinear Optics, Part, I, i-da. M.W.Evuiis and S.KIellch, p.249 (Wiley, N.Y., 1003)

[4] ANDPiHSON, I). Z. - MIZRAIII, V. - SIPB, J. IÍ,: Model for second-harmonic generation in glass optical filters basal on asymmetric plioloelcclron emission from defect sites Optics Letters, 16 (11)91), 706

[5] MARGUL1S, W. - CARVALIIO, I. C. - LI3SCIIE, IJ.i Preparation of frequency-doubling fibers under UV excitation Optics belters 16 (1001), I'187

[6] LAWANDY, N. M. - DRISCOL, T. J. - ADLEIl, С J.i Tcsl of directional photoion-izalion models of second-harmonic general ion in optical fibres ИСК Proceedings-,! 130 (1992), 133

[7] DOMINIC, V. - FEINBERG,./.: Growth vale of second-harmonic generation in glass Optics Letters 17 (1992), 1761

[8] CIIMELA, P. - РЕТНЛСЕК, J. - ROMOLINI, A, - PASCUCCI, Т.- el- al,; Comments on directional pholoionization model of second-harmonic generation in doped glass fibers Optics Communications 112 (1994), 101

[9] DEMOUCIIY, G. - BOYISH, G. II.: Growth rate of second-harmonic generation in optical fibers Optics Communications 101 (1993), 385

[10] CIIMELA, P. - PETRÁCEK,.L: Limiting efficiency of self-organized second-harmonic generation in dopcd-glass fibers by self-saturation Optica Applicata, in press

This research has been conducted at the Institute of Physical h'ngincering as part of the research project "Self-organized nonlinear phenomena" and has been supported by TU grant No. Л 9/94.

638


OPTICAL FIBER DIAGNOSTICS

O. Samek

TU, Fnc. of Mcch, Eng., Institute of Physical Engineering Technická 2, 661 69 Brno

Key words: holographic interferometry

This paper deals with the evaluation of holographic interferograms to determine distributions of change of refractive index. The transparent media under consideration are treated as phase object. The experimental setup was set, a holographic Mach-Zchnder interferometer [2], in order to investigate phase objects (e.g. a flame from candle, an optical fibre) by means of a new approach of holographic interferometry — a Fourier-transform method [1, 2]. The method enables by computer processing automatic discrimination between wave-front form. The method is easy to apply because it uses no moving components. The Fourier-transform method for computing phases can produce a phase map automatically without the need for locating fringe centres or assigning fringe orders. This feature not only simplifies analysis of interfcrograms but allows for use of these phase calculation methods in the active optics experiment in which our testing sample was measured. Knowing phase distribution one c;in easy calculate index of refraction that is desirable for accuracy optical fibers testing.

Calculations. The Fourier-transform method suggested by Takcda et al. [lj, can be written by

g(x, y) = a(x,y) + b(x, y) cos[2ff/0a; + ф(х, у)], (1)

where a(x, y) and l>(x,y) are unwanted irradiance variations, ф(х, у) is the phase of the wave front, and /o is the spatial carrier frequency — the fringes arc added by the tilting of the wave front in the interferometer. Thus

</(.r, y) = a{x, y) + c(x, у) схр(2тггУо.г) + c(x, y) cxp[-2itifQx), (2)

where c(x,y) = Q.5b{x,y)cxp[i(f>(x,!j)]. (3)

Next, Eq. (2) is Fourier transformed with respect to a- by the use of a fasl-Fourier-transform (FFT) algorithm, which gives

G(f,y) = A(f,y) + C(f-f0,y) + C'(f+f0,y); (4)

Because spatial variations of a(x, y) are slow compared with / 0 , the function G(f,y) will be a trimodal function with peaks at —/0, /o and the origin. The function C(f — /o,?/) can be isolated using a filter centered at fo- The carrier frequency can be removed by shifting C ( / —/o,2/) by /o to the origin to give C(f,y). The inverse transform of C(f,y) with respect to / yields Eq. (3). From Eq. (3),

^'y ) = tan ЩШу (5)

now the phase distribution is obtained using computer software.

639


Experiment . The experimental setup for testing phase objects was set [2]. Light from IIc-Nc laser was used in order to investigate phase object — a flame from candle. Using above described method and developed software the phase distribution (phase map) was obtained.

The interference pattern was recorded by CCD camera and in the following a sigiml was transformed by using computer software to 512x512 pixels. Knowing phase distribution along a line one can calculate the change of refractive index. The line can be chosen by software. It can be applied for testing optica! fibre.

Conclusions The experimental setup for testing phase object (e.g. candle flame, optical fibre) was set. We tested the flame from candle [2] and the index of refraction was calculated. The method is suitable for phase tomographic reconstruction as well [4]. In a view of the future steps, we would like to examine the optical fibre in this manner on the constructed interferometer.

References:

[1] TAKEDA, M. - INA, II. - KOBAYASIII, S.: Fouricr-lmnsform method of fringe-pattern analysis for computer based topography and interferometry. J. Opt. Soc. Am. 72, 1981, 1, 156-160.

[2] LISKA, M. - PETRÁCEK, J. - SAMEK, О. - PROCHÁZKA, I.: llologmjická inler-feromelrie. Jemná mech. a opt. To be published.

[3] BRINGHAM, 0.: Fast Fourier Transformation. Prentice Hall, London 1987. [4] VUKICEVIČ, D. - JAGER, II. - NEGER, T. - PHILIPP, II.: Tomographic recon

struction of the temperature distribution in convcctivc heal flow using multidirectional holographic interferometry. Applied Optics 28, 19S9, 8, 150S—1516.

7%is research has been conducted at the institute of Physical Engineering as part of the research project "Optical fiber diagnoslcs" and has been supported by TU grant No. A 10/94-

640


LASER TWEEZERS

M. Liška

TU, Fac. of Mechanical Eng., Institute of Physical Engineering Technická 2, 616 69 Brno

Key words: laser beam, optical tweezers, manipulation of particles

Laser beams have typically high intensity of radiation and precisely specified direction of propagation. These two properties give rise to oriented forces which may be used for manipulation and trapping small particles. This fact offers new approaches to the laser research from the physical point of view and many interesting applications in various sciences, e.g. in physics, chemistry and biology [1,2].

Let us consider a transparent dielectric spherical particle having the index of refraction ilk- Suppose the particle may accomplish free movement in an immerse liquid with the index of refraction щ. The particle is illuminated by a laser beam which is operated in the TEMoo mode and which has a Gaussian beam profile. Л part of the laser beam a (cf. Fig. 1) acts on the unit area of the spherical surface at the place of incidence by a force that can be evaluated from differences of the density of momentum at points of the spherical surface (cf. Fig. 2). The force F' is the sum of two forces

F1' = Fr' + Pj.

The force F' has the direction of the inward normal to the spherical surface. The force F{ has two components. One of them has the direction of the z-axis, the other one is normal to the laser beam axis and points to the axis, if л* > тц, and from the axis, if n* < n,-. Similarly, we may calculate the radiation pressure arising from the beam reflection and refraction at points where the beam leaves the spherical particle. The force acting on the unit surface of the boundary is

F°=F° + F°. Here, the force F° has the direction of the outward normal and the force Ff has a component in the direction of the z-axis and another one normal to the laser beam axis and oriented to the beam axis if Пк > n; and in the opposite way, if n/t < n,-.

Consequently, the sum F' + F° has one component in the direction of the z-axis and another one oriented to the beam axis, if iik > Щ.

Similarly, we may conclude that the beam b (symmetrical to the beam a) acts on the spherical particle by the force which, again, has its components in the direction of the z-axis and in the direction normal to the beam axis and pointing from the axis, if тц > щ. As the laser beam hat. larger intensity at a than at 6, the crucial influence on the movement in the radial direction has the radiation pressure of the beam b. The resulting radiation force acting on the spherical particle is the sum of all contributions which act on the whole surface of the particle. It is obvious that it has one component in the direction of the z-axis and the second one normal to the beam and pointing to the beam axis, if n* > n,-, and from the beam axis, if ?ц < щ. From the physical point of view the result is obvious - the dielectric particle is pushed by photon flow to the position where the energy of the system has its minimum. Hence, we may conclude that the laser beam pressure can be used for the handling of particles of the micrometer size.

641


Fig. 1: A dielectric sphere ofT the axes of Fig. 2: Momentum density of the incoming, laser beam reflected and refracted waves

References:

[1] ASHKIN, A.: Acceleration and Trapping of Particles by Radiation Pressure, Phys. Rev. Lett. 24, 1970, 156.

[2] CHU, S.: Laser Manipulation of Atoms and Particles. Science 253, 1991, 861 - 866.

This research has been conducted at the Institute of Physical Engineering as part of the research project "Laser Manipulation of Particles" and has been supported by TU grant No. C34/94.

642

WORKSHOP 95 ELECTRONICS fc OPTICS

A SHEARING INTERFEROMETRY METHOD FOR DETERMINING

THE STATISTICAL QUANTITIES OF RANDOMLY ROUGH SURFACES

M. Ohlídal, I. Ohlídal*


*MU, Fac. of Science, Dcpt. of Solid State Physics Kotlářská 2, 602 II Brno

Key words: optics, shearing interferometry, surface quality, image processing

Intcrfcroinctric methods belong to the most important optical methods for investigating surface roughness because they arc reliable and relatively simple compared with the other methods. This statement is especially true for the methods of shearing interferometry and therefore wc dealt with developing new methods of this optical technique.

We developed the method that can be applied by means of any shearing interference microscope. We utilized the Zeiss Epival Interphako (ZEI) and Zeiss Peraval Interphako (ZP1) microscopes for employing this method. The ZEI and/or ZPI microscope is used in reflected and/or transmitted light by a surface studied. Arrangements of these microscopes are presented in our earlier papers [1, 2]. Within both the microscopes mentioned the waves interacting with the rough surfaces investigated arc titled and shifted mutually. These titled and shifted waves can interfere and the intcrferograms originated in this way contain dark and bright interference fringes the centres of which arc represented by more or less deformed lines. The form of these fringes can be used for determining the basic statistical quantities of the rough surfaces if a suitable statistical analysis of the fringes mentioned is performed. This analysis is based on the following equations:

("o - ") q

k * ~ P - (2) 2n0 <7

where Л, H0 and n arc the wavelength of the light source, the refractive index of the ambient and the refractive index of a transparent material bounded by the rough surface. The symbol p and/or q denotes a deviation of a point of the fringe from the straight-line representing the mean line of the fringe and/or the distance between the mean lines of the adjacent fringes. The quantity /i is expressed as follows:

h(x, y) = li(x + т,у)- h(x, y) (3)

where h(x,y) is a random function describing the rough surface and x, у and r denote the cartesian coordinates and the value of the shear (shift), respectively.

643


The values of h can be determined by using equations (1) and (2) for many points of the interferogram corresponding to a certain value of r which can be measured. These values of h give the rms value er/, of the random quantity h. The dependence of a/, on r can be determined after applying this procedure for several intcrfcrograms corresponding to the different values of r . By means of the dependence ^A(T) determined one can evaluate the values of the rms value of the heights of the irregularities, the rms of the slopes lan/3 and the autocorrelation length У of the rough surface in the way described in detail in our works [1-3]. Moreover, it is possible to determine the dependence of the autocorrelation coefficient C(T) as well.

Thus, within our method one can determine all the main statistical quantities having a practical meaning from the point of view of applications in optics, fine mechanics and engineering.

There are three main advantages of our method in comparison with the other methods:

1) Simple commercial arrangements can be employed for the application of this method 2) Modern method of computer techniques can be used in an ciFcclivc way within the

method 3) With the method the analysis of the rough surfaces is performed by means of the form

of the fringe centres.

Thus, a contrast of the fringes need not be used for analyzing the surfaces (interpretation of the contrast is complicated by various factors, e.g. by coherence properties of the light sources).

References: [1] OHLÍDAL, I. - NAVRÁTIL, K.: Analysis of the basic statistical properties of randomly

rough curved surfaces by shearing interferometry Appl. Opt. 26 (1985) 2G90-2695

[2] OHLÍDAL, I. - NAVRÁTIL, К. - OHLÍDAL, M. - DRUCKMULLER, M.: Characterization of the basic statistical properties of very rough surfaces of transparent solids by immersion shearing interferometry Appl. Opt. (in print)

[3] OHLÍDAL, M. - OHLÍDAL, I. - DRUCKMULLER, M. - FRANTA, D.: A method of shearing interferometry for determining statistical quantities of randomly rough surfaces of solids Pure Appl. Opt. (submitted publication)

This research has been conducted at the Institute of Physical Engineering, Fac. of Mechanical Engineering, TU Brno as part of the research project "Melrological applications of coherent optics methods in mechanical engineering and nanotechnologies" and has been supported by TU grant No. В 89/93.

644


LATTICE AND SHAPE AMPLITUDES

J . Komrska

Institute of Physical Engineering, Fac. of Mech. Eng. TU Technická 2, 616 69 Brno

Key words: Small crystals, lattice amplitude, shape function, shape amplitude.

The sum of phasors

S{X; n) = £ exp(-i27rx'J') • X) ' (1)

is encountered whenever we calculate the Fourier transform of a function characterizing a set of identical and identically oriented objects the mutual position of which does not vary in time. If the single object is specified by a function /0 the whole set is described by the sum

/(í) = t/o(í--í(i)).

Its Fourier transform F(X) = FT{f(x)} = F0(X)S(X;n)

is the product of two functions. The first one, F0{X) = FT{f0(x)}, is fully specified by the single object /0 whereas the second one, the sum of phasors 5(A'; и), is determined just by mutual positions of the objects (and does not depend on the shape and other properties of the objects).

If the identical objects form a finite lattice with basic vectors a,- and occupy a volume V, the position vectors x^ are lattice vectors хц = J^u,U{. The sum of phasors is then a periodic function called the lattice amplitude. It has the periodicity of the reciprocal lattice specified by vectors a,"1 (S;-aJ* = i,;) and it can be expanded into a multiple infinite series of the so called shape amplitudes Gi(X):

S(X;n) = ^G(X-XK), (2) К

where Ajj — £ hiaj1 are reciprocal lattice vectors, Gi(A') = FT{s(x)}/Vo, V0 >s the volume

of the unit cell and s(x) is the shape function of the finite lattice (i.e. s(x) = 1, if x € V, s(x) = 0, if x £ V). It is remarkable that the lattice amplitude S\X; n) is well approximated by the sum of a very small number of shape amplitudes G\, even by a single one.

We may illustrate it by an example of the one-dimensional lattice. The lattice amplitude of the lattice formed by n objects and having the lattice parameter a is S{X; n) = sin тгапХ/sin isaX. Taking the shape function s(x) = rect(x/na), the shape amplitude is Gi(X) = nsmiranXjiranX and the equation (2) provides the identity

sin z an X _ ^ s\n[nn(aX — h)] . . sinjraA' ~n

hhoo nx{aX-h) ' ^ '

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The continuous line in Fig. 1 indicates the function on the left-hand side of (3), whereas the points indicate the sum of three terms of the scries on the right-hand side (a = 1, n = 9, A = - 1 , 0, 1).

The habitus of a three- (two-) dimensional finite lattice is always a polyhedron (polygon). Then the shape amplitude G\ can easily be evaluated as the corresponding Fourier integral can be expressed by an algebraic * expression (cf. J. Komrska: Optik 80 (1988), 171). To facilitate the calculation of lattice amplitudes of small crystals we have calculated the shape amplitudes of all Platonian bodies. As an example, the left-hand part •• of Fig. 2 shows the projection of the icosa-hedron in the direction of the three-fold sym- pjg. [ metry axis and the right-hand part gives the central section through the shape amplitude by the plane perpendicular to the three-fold axis. Hence, the two parts of the figure represent a pair of functions related (apart from a constant factor) by the Fourier transform.

This research has been conducted at the Institute of Physical linginecrimj as pari of the research project "Diffraction of Radiation by a Set of Identical Objects" and has been supported by TU grant No. С Ц/0/\.

646


THE RIGOROUS ANALYSIS OF THE QUANTUM ELECTRON WAVEGUIDES

F. Urban, F. Matějka, R. Redhammer*

VUT, Рас. of Electrical Eng., Dept. of Alicroelcctronics Udolni 53, 602 00 Urno

*STU, Fac. of Electrical Eng., Dept. Microelectronics Ilkovicova 3, Bratislava-Mlynska dolina

Key words: quantum waveguide, bound state, cross-resonance, effective mass, potenciál profile, quantum well

Semiconductor layered microstructures. Semiconductor layered microstructures have been used extensively to study a lot of new quantum effects based on the quantum and wave-like nature of fermions. There are even mezoscopic structures where the quantum effects were observed and which are believed to bring the impact in the development of the electro-optic devices. Crystalline semiconductor lieterostructurcs arc those which can provide significant, differences in both the band edge potentials and the effective mass of moving particles. Moreover, physical properties of the structures are influenced by the distinguishable anisotropic particle mobility which occurs in strained layers in particular. The last seems to have particular importance for behaviour of the confined Bloch electrons in semiconductor layered structures. This paper presents an extensive theoretical study of the waveguide nature of slab multilayer semiconductor microstructures. The aims of this work were to establish, within a simple kinetic energy based formalism, a predictive model for the electron guiding properties of an arbitrary slab structure, either quantum well-like or even quantum barrier-like, and to show how significant the influence of the effective mass of moving particles can be for forming the quantum waveguides.

Quantum electron waveguides. Starting from the cross-icsonance condition for bound states of the semiconductor well-like quantum structures, wc generalized the theory of the particle behaviour to the case of nonrcctangular incidence of a particle to the two material interface. Taking into account the possible effective mass anisotropy of the moving particle wc formulated a new condition of the cross-resonance and the particle confinement for the generalized case of the three-dimensional particle motion in layered structures. The condition specifies the behaviour of the structure as a planar quantum waveguide. The global transfer matrix approach was applied for searching out the cross-resonance eigenstates and for the evaluation of the particular quantum guidance properties of the various well-like and barrier-like quantum structures. The structure properties which describe their waveguide behaviour were evaluated in terms of mode diagrams. It allowed to judge how both the structure potential relief and the particle effective masses influence the structure behaviour. We formulated the conditions specifying whether the open and/or closed mode area can occur in the structure mode diagram. The results show that the general feature sufficient for occurring the guidance conditions in a quantum structure is the existence of the positive effective mass step in the structure cross-section. In this case both well-like and barrierlike layered structures can act as a quantum waveguide confining the longitudinally moving particles whereas in case of either the negative or no step in the effective mass the only well-like structures have a limited ability to guide the moving particles.

647


We also demonstrated the capability of presented method to analyze the properties of the arbitrary shaped layered structures giving the example of the mode diagrams calculated for the triangular well and barrier guiding layers. The study of the multilayer structures gave the results in revealing some peculiarities in the multilayer structures like tripple quantum wells and multilayer quantum mirrors which can help us bring more light in full understanding of their functionalities. The quasibound states like an isolating sttitc and a short circuit state were found and described, and even the acurnulation properties of the reflective structures were analyzed and a hypothesis for the quasibound state life time determination was introduced.

New knowledge on the potential and mass relations to the mode curve shape of the guiding lateral structures is opening space for the design of the complex electron waveguide structures with predictable performance. Hence we can draw the electron waveguides with different mode curve position and steepness.

As a particular result of it we reported the possibility of creating an electron waveguide structure with a periodic corrugation in the longitudinal charge distribution. The periodic distribution is attainable even when the broad energy spectrum feeding of the electron waveguide is applied. This effect is produced by the selectively coupled pair of asymmetric electron waveguides which offers a sharp mutual crossing of their original mode curves. Energy coupling evoked by placing one electron waveguide close to the other causes the coupled mode curves to deviate from the original shape but only closely around the point where the imperturbed mode curve intersects. This feature brings about the energy selective mode coupling.

As a consequence of that the charge distribution in the coupled waveguides fed by broad spectral electrons is corrugated periodically. The longitudinal periodicity of the charge variation can be adjusted by the variation of the mutual electron waveguide distance. Coincidence of the periodic charge distribution with an optical wave can be easily arranged and consequently new opto-electronics and electronic devices can be envisaged.

Conclusion. The introduced theory can become a first step to investigation of new particular quantum effects and photonic devices based on them. Potentially, there is a tool for analysis of the currently made structures from more general point of view to improve their design and, also, there is a tool for looking for new qualities in the quantum devices.

References:

[1] GAYLORD, T. K. ct al.: Semiconductor Electron Wave Slab Waveguides. J. Appl. Phys. 66(3), AUG 1989, pp. 83-1485.

[2] URBAN, F. et al.: The Waveguide Behaviour of The Balistic Carriers in Confined Quantum Stales. Radiocngineering, Vol. 1, DEC 1992, pp. 8-13.

This research has been conducted at the Department of Microelectronics, Technical University of Brno as part of the reseaivh project "Mczo and Micro structures for Optoelectronic Applications. Theory and Technology." and has been supported by TUgrant No. A 75/94-

648


A MEASUREMENT OF SURFACE ROUGHNESS

BY ANGLE SPECKLE CORRELATION

M. Ohlídal, J . Honec*


*TU, Fac. of El. Eng. and Сотр. Sci„ Inst, of Automatic Control and Instrumentation Božetěchova 2, 612 66 Brno

Key words: optics, light scattering, surface quality, image processing

A randomly rough surface (which is rough from the optical point of view) irradiated by a coherent radiation creates the speckle field in the space around the surface. The statistical properties of the field are in close relation to the statistical properties of the surface generating the field. The information on the random surface roughness parameters of the surface can be obtained in several ways. One of them is the measurement of the angular correlation of the speckle fields. Its principle was first published in [1] , its theory was improved in [2] and [3].

In the original proposal the surface under study was irradiated by the collimated laser beam with the angle of incidence 45°. The scattered laser wave exposed the holographic plate which was appropriately placed in the vicinity of the surface. After the first exposure the rotation of the surface was carried out around the axis going through the surface. The angle of the rotation was less then 2°, and the laser beam was screened during the rotation. When the rotation was finished, the laser beam again irradiated the surface and the second exposure of the same holographic plate was carried out. The simultaneous photographic record of the two particularly decorrclated specklegrams was obtained in this way. Their decorrelation is caused by the surface rotation and it is in relation to the surface roughness.

Then the plate was processed in the ordinary way and placed in the convergent laser beam. Young's fringes arised in the Fourier plane of the plate. Their intensity profile was measured by the linear photodetector in the direction perpendicular to the fringes. Its output signal was digitized by the A/D converter and fed to the computer. The standard deviation of height surface fluctuations and the correlation length of the surface are determined from the output signal by means of the Marquard least square method. The terms in [1] and [3] are used for the purpose. It is obvious that the mentioned method involves two steps, the photographic record and its processing, which are separated by the plate chemical processing. The fact significantly lengthens time needed for the surface roughness determination. Therefore it is desirable to exchange the photographic record of specklegrams by some other recording tool. This is the content of the report. The CCD camera chip was selected as the appropriate tool because it offers the possibility of instant processing of the image records. A further advantage of the chip with respect to the holographic record is its linearity in the response. This fact makes it possible to avoid the additive procedure needed for the quantitative evaluation of the holographic plate nonlinearity. The geometrical arrangement of the method is the same as in [2] only the holographic plate is replaced by the CCD camera. The procedure of recording of the specklegrams before and after the

649


surface rotation is the same too. Of course now these specklegrnms are digitized by the card developed at the Institute of Automatic Control and Instrumentation, FEECS, TU Brno and processed by software system PCW [4] also developed at this Institute. The system allows the FFT transformation of the image record. The procedure of processing of the specklegrams obtained in the way mentioned above is as follows:

1) The mutually corresponding spccklegratns are added up in the computer memory. It corresponds to the two specklegrams on the holographic record.

2) The FFT is carried out with the sum .

3) The power of the FFT is calculated . 4) The section of Young's fringes is selected perpendicularly to the fringes in the image

of the result of the previous operation. 5) Values of the section are fitted with the equations (20), (21) or (24), (25). Correspond

ing values of the standard deviation of height surface fluctuations and the correlation length of the surface are the resulting values.

At the present the points 1) - 4) are resolved (time of performation is tens of seconds), the point 5) is solved.

References:

[1] LÉGER, D. - MATH1EU, E. - PERRIN, J. C : Optical Surface Determination Using Correlation Technique Appl. Opt. 14 (1975) 872-877

[2] OHLÍDAL, M.: Comparison of the two-dimensional Fraunhofer and two-dimensional Fresnel approximations in the analysis of surface rovgness by andle speckle correlation. I. Theory 3. Mod. Opt.38 (1991) 2115-2135

[3] OHLÍDAL, M.: Comparison of the 2D Fraunhofer and the 2D Fresnel approximations in the analysis of surface roughness by angle speckle correlation. II. Experiment, to be published

[4] HONEC, J. - VALENTA, P.: PCW manual ÚAMT FE VUT, Brno, 1993

This research has been conducted at the Institute of Physical Engineering, Fac. of Mechanical Engineering, TU Brno as part of the research project "A Measurement of Surface Roughness by Angle Speckle Correlation" and has been supported by TU Brno grant No. С 25/Щ and GACR grant No. 101/94/0555.

650


MEASUREMENT, PROCESSING AND EVALUATION

OF EXPERIMENTAL PROCESSES L. Bejcek

TU of Brno, Fac. of Electrical Eng., Dcpt. of Automation and Measurement Eng, 2 Božetěchova Str., 612 66 BRNO

Key words: injection moulding, measurement, data acquisition

The Materials Engineering Institute, Technical University of Brno, Faculty of Mechanical Engineering is engaged in research on thermoplastic plaster systems, which are used or utilized in preparation of ceramic mixtures suitable for high-pressure injection moulding. This technology enables effective, economic production of quality precision ceramic parts. To this aim, optimalization of technological conditions is necessary, especially the temperature and pressure of binder removal processes.

The scale of experiments was very wide and exacting both from the point of view of time (experiments lasting dozens of hours) and content (lots of information). In addition, the experiments had to have exactly defined conditions and had to be reproducible. This was the reason why the Materials Engineering Institute proposed cooperation with the Institute of Automation and Measurment, TU FEI.

Teams from the both of these institutes designed and realized project enabling automatic measurment, processing and evaluation of these experimental processes for extracting ceramic mixtures.

Our central problem was the measuring the mass of the tested ceramic mixture on a scale from one to hundreds, of grams with a resolution of better than 1 mg. The temperature conditions ranged from 100 to 1000 degrees centigrade under pressures from 10 Pa to 100 kPa. The experiments lasted from 1 to 100 hours. Other problems included the design of a suitable regulation algorithm to reach and maintain predefined working conditions in an experimental extract furnace, the design of software enabling measurment of control signals from sensors and processing, and theevaluation of the process in real-time.

We designed and tested a few sensing systems and methods of measurment (including fiber optic sensors). Finally we used resistive platinum thermometers and thermocouples for temperature, and the Pirrani gauge and piezoresistive principle for pressure. Mass was measured with a laboratory module balance produced by METTLER Toledo, model College 244DR. It works on the principle of compensation with capacitive sensing of position.

We discovered, and tried to correcte the pressure dependence of measured values for in mass of this balance (which is non-monotonous and has a hystcresion, in addition) by cooperating with the Mettlcr distributor for Czech Republic, and subsequently with the distributor for Austria, but we failed. We had to contact the swiss producer directly. We discussed the problem and made some experimental verifications. After this, we were leant a different model of the balance — B303. The principle of the mass measurment is the same, but the position is sensed photoelectrically. The pressure and temperature dependencies of both models of the balance were compeared. Characteristics and hysteresis in various gas surroundings were then evaluated. The results of these evaluations were analyzed, and

651

WORKSHOP 95 KUÍCTIIONICS к OPTICS

methods of approximation were deigned to compensate for dedense, and remove these spurious dependencies, We also had to change evaluative software a number of times, for these reasons, Wc used LabVHSW and LabWindows by National Instruments as evaluating software in our project, (the drivers for both the balances included),

Functional tests of the whole system (testing ceramic mixture in an extract furnace), with automatic regulation of temperature and pressure in dependence on decrease of mass, were carried out in the last quarter of year.

The system is still running improvment and tests, but wo can formulate some concrete conclusions,

t, Pressure dependence of the sample mass on the scale of 10 to 100 к Pa is comparable in both models and is caused by absorption and desorption.

2. The balance with the photoelectric position-sensor (model B303) has more linear pressure of mass than the balance with capacitive sensing (College 244DR),

3. Pressure dependence of 13303 has lower time-dependence on the rate of temperature change, and lower hysteresis,

4. Temperature dependence of the tested sample mass was eliminated in both models of the balnncc,

5. The experimental system fulfills qualitative and quantitative requirmciits for the analysis and optimalization of the extract processing of ceramic mixtures.

The system designed in our project can be applied to any similar process, where large amounts of data about physical quantities from sensors must be processed and evaluated,

This information can be made immediately available, so it can be used for real-time regulation of the process. Our system has the additional advantage of being based on fairly universal software packages, so it can be easily adapted to many related tasks.

References; [1] TRUNEC, M. - CUILAR, J,: Injection Moulding of Aluminc Bioccramica 8-th

C1MTEC '94, Florence, Italy 1994 [2] IEE ^88 and VXIbus Control, Data Acquisition and Analysis. National Instruments

1994

This research lias been conducted at the Department of Automation and Measurement Engineering as part of the research project "Measurement, Processing and Evaluation of Experimental Processes" and has been supported by TU of Brno, Grant No. B\.

652


AN IMPROVEMENT OF THE OPTICAL INTERFEROMETRY FOR EHL STUDY

M. Hartl , I. Krupka

TU, Fac. of Mechanical Eng., Institute of Design Technická 2, Brno 616 69

Key words: elastohyclrodynamic lubrication, film thickness, optical interferometry

The primary role of fluid lubrication films is generally friction reduction and wear at the interface of the rubbing surfaces of the tribological systems. This is achieved by forming a thin film that can vary in thickness from just a few monomolccular layers of adsorbed or chemically reacted material in the regime of boundary lubrication, to thickness exceeded 1 /im in the regime of hydrodynamic lubrication. Elastohydrodynamic lubrication regime (EHL) is founded between these regimes of lubrication where local elastic deformation of the nonconforming rubbing surfaces in relative motion produces a coherent lubrication film of the thickness from 0,1 to I /im which prevents from mutual interaction of asperity. The idea of to apply of the interference of light for determination of thin liquid film thickness is over three hundred years older. The first use of optical interferometry in the study of elastohydrodynamic lubrication film is attributed to M. T. Kirk (1962). A.Cameron, R. Gohar and H. A. Spikes from Imperial College of Science and Technology in London have contributed most to development of this method since.

The aim of our research is the extension of applicability, increasing of accuracy and resolution of conventional optical interferometry technique. The conditions occuring in the elastohydrodynamic lubricated point contacts were modelled on the conventional optical test rig. The basic element of this test rig was a couple of friction elements consisting of a glass disc of 100 mm in diameter, and of a steel ball of 25,4 mm in diameter. Top surface of glass disc was coated with anti-reflection coating, lower with a 10 nm sputtered chromium semi-reflecting layer. The ball was loaded into contact with the flat surface of the glass disc by a lever and spring balance mechanism. The glass disc rotating around a vertical axis was driven by a variable speed motor. Both the thickness and shape of the lubrication film were determined from intensity distribution of interference fringes which arise from the coherent superposition of two light waves reflected in the interface between chromium semi-reflecting layer and lubrication film, and in the interface between lubrication film and deformed steel ball. Laser interferometr with red He-Ne laser and high resolution CCD (Charge-Coupled Device) array of the solid state camera facilitated precise localization of interference fringes in lubrication film. The interferograms were digitized and stored in micro-computer where they were processed by special software. The process of these interferometric images consisted in: - Image sharpening and contrast enhancing. - The correction of distortion of image caused by nonuniform sensitivity

of individual CCD elements. - Removing of nonuniform illumination. - Numerical filtration of image. - Intensity calibration and photometry analysis. - Determination of both the thickness and shape of the lubrication film

653


and their mapping. Table 1 summarizes the typical test conditions employed in our study. Figure 1 showes a schematic diagram of the experimental apparatus and Figure 2 three-dimensional representation of ciastohydrodynamic lubrication film thickness computed from iutcrfcrogram (for the typical test conditions).

Elipticity parameter Dimensionlcss speed parameter Dimensionlcss load parameter Dimensionless materials parameter

к U W G

1 7.1 x JO"12

2.4 x 10"° 2700

Tab. 1: Typical experimental conditions.

t Steel Ball 2 Glass Disc 3 Microscope Objective 4 Beam Splitter 5 Lenses 6 Rotated Dlspeision Plate 7 He Ne Laser 8 ССО Camera 9 Image Processor 10 PC

Fig. 1: Schematic diagram of the experimental apparatus

Fig. 2: Three-dimensional representation of EIIL film thickness (only half of the contact)

This research has been conducted at the Institute of Dcsiyn as part of the research pi-ojcct "Experimental Solution of Thermal EIIL of Rolliny/Slidiny Point Contacts" and has been supported by TU grant No. D/l.

654


SYSTEM FOR THE MEASUREMENT OF THE BORE

TEMPERATURE PROFILE

M. Satorie, J . Vedral*

CTU, Fac. of Electrical Eng., Dept. of Measurements Technická 2, 166 27 Praha 6

Key words: temperature measurement, temperature sensors, smart temperature probe

Geothermy is a branch which studies measurement and explanation of the temperatures and the heat flow in the crust of the Earth and determination of the temperatures in the core of the Earth. During the last several years geothermy has been progressing like other science branches which require improved devices for measurement of the temperature under the crust of the Earth. From the bore temperature profile we can see an influence of the Earth's heat source on the temperature in the Earth's crust. The bore temperature profile is a dependence surrounding the temperature of the probe and the distance of the probe from the Earth's surface, which means the dependence on a probe depth.

We have to consider these requirements: an unbalanced move of the probe in the bore with a speed of about 10 cm/sec, a depth of the bore of more than 1000 m, a difference of the temperature of 30 °C , a resolution of 0.005 °C, and a long-term stability of 0.1 °C.

This system can be realised in any of the following ways:

1. By a simple probe with a resistance temperature sensor. The resistance is transmitted to the Earth's surface and is measured by the resistant bridge. But, the cable's length (more 1000 m) and its disturbing are the disadvantages of the system.

2. By a probe containing a resistance temperature sensor witli a voltage-frequency converter. The frequency is transmitted through the cable (optical) to the surface and processed by the counting of the impulses during a constant time. In this way we can achieve a high resolution of the temperature measurement and also eliminate a disturbing of the data transmission.

3. By a interferometer. The optical cable placed in the bore changes its reflection index depending on the temperature. The complication in this method could be a very long optical cable.

4. By a smart probe which contains a resistance temperature sensor, voltage-frequency converter, and the memory of the measured values. The temperatures and the immediate depth are synchronised by the trigger of the probe and by the unit at the surface. The depth is calculated from the length of the rope. The realisation of the system with the smart probe was chosen after consultation with a specialist from the Geophysics Institute of the Czech Academy of Science. The most suitable sensor is the four-staple platinum measuring resistor PtlOO, which is able to secure sufficient resolution. The other temperature sensors (for example, thermistors or thermocouples) arc not satisfactory because they do not have a linear dependence resistance and the temperature, and they are not stable in time. The emitter junction of the transistor is not suitable either, for its lack of stability and reproducibility.

655


System with smart probe. The system contains the probe that records the surrounding temperature of the sensor (temperature in bore) in the memory and the unit on the surface that records in memory the immediate depth of the probe. The depth is derived from the rope length of the probe. This configuration removes the problem of transmission of any data from the probe in the bore to the Earth's surface. The immediate temperature stored in the memory is associated with the immediate depth of the surface unit. This association is provided by the time synchronisation of the temperature sampling by the probe and the length sampling of the unreel rope by the surface unit.

Description of the probe. The voltage of the measuring resistor is amplified and converted to the frequency thcit makes the digital process possible. The circuits of the probe are made by the microcontroller 80C31. This microcontroller controls the probe, records the data in memory, and transmits the data by serial line RS232 to the computer IBM PC. Five sintronized NiCd accumulators with specified voltage 1,2V and capacity <IAt arc used as the source for the probe. That is sufficient for the full time measurement with large reserve.

Description of the surface unit. The depth of the probe under the Earth's surface is defined by the length of unreeled rope. The length of rope is measured by the incremental sensor. The signal indicating the direction of unreeled rope movement (moving direction of the probe in the bore) is conveyed to the surface unit. This provides measuring even during the upwards movement of the probe. The digital circuits of the surface unit are basically the same as the probe. There is a six-digit display for monitoring the immediate depth of probe, for monitoring the time from the beginning of the measurement, and for communicating with the user, which arc necessary for the service of the system connected to the microcontroller.

Algorithm of the measurement and the recording data. The system is started by connecting the probe with the surface unit via the serial line RS232. After the measurement has been completed, the data from the surface unit and from the probe arc transmitted to the PC and processed. The data processing is performed with regards to the time constant of the sensor and the gradient of the temperature by convolution. Long-term temperature stability is verified in the temperature stable bores.

References: [1] BRUNET, J. - KŘESL, M.: The Thermal Probe. The University of Western Ontario,

Dep. of Geophysics, 19S9. [2] KftIZ, F. - VEDRAL, J.: System pro měření teplotního profilu vrtu. Úvodní studie к

řešení, ČVUT FEL Praha, kat. měření, 1992. [3] ČERMÁK, V.: Země a její tepelná historie. Academia, 1967.

This research has been conducted at the Department of Measurement as part of the research project "Climate changes in Eastern Evropě infei'ed from borehole temperatures, US Government Agency" and has been supported by GFU CAV grant No. 92037.

656

WORKSHOP 95 ELECTRONICS fe OPTICS

SINGLE CRYSTAL SCINTILLATION DETECTORS FOR LOW VOLTAGE

AND LOW VACUUM SCANNING ELECTRON MICROSCOPY

. u R. Autrata, J. Jirák*, J. Spinka*

Academy of Sciences of the Czech Republic, Institute of Scientific Instruments Královopolská 147, 612 64 Brno

+TU, Fac. of Electr. Engng. and Informatics, Dept. of Electrotechnology Antonínská 1, 602 09 Brno

Key words: LV SEM, ESEM, signal detection in LV SEM, signal dectection in ESEM

The results obtained from the foregoing investigation of the properties of single crystal scintillators have shown good possibilities of using the single crystal of yttrium aluminium garnet (YAG) activated by trivalent cerium as a scintillator for annular and planar detectors of backscattered electrons in the scanning electron microscope (SEM) [1]. The annular detector is formed by a scintillator ring optically connected to the light guide. The planar detector is formed by a scintillator disk whose outer peripheral area is optically connected to the light guide. The measurements have shown that the low energy (0.8 - 2 keV) of electrons incident upon the scintillator is insufficient to effect an efficient transfer of photons guided by the light guide toward the photocathodc of the photoelectric multiplier. Therefore, the experiments connected with acceleration of the backscattered electrons in an electrostatic field produced by a high voltage electrode deposited on the scintillator were carried out. Computer simulation of electrostatic fields and electron trajectories was a basis for the experiments that have proved that the configuration of such a system contributes to an increase in detection efficiency. The condition for this is a modification of equipotentials of the electrostatic field by using a metal grid with a low negative voltage. The experiments made on the adapted Tesla BS 340 SEM in the backscattercd electron energy range of 0.8 - 3 keV have shown that, when the planar detector is positioned close under the pole piece of the electron optical SEM body, high takc-oiT angle backscattcred electrons incident upon the scintillator are detected. This results in obtaining material contrast. In the electrostatic (relatively low) field produced in this way the low take-off angle electrons excited in the specimen are not guided toward the planar detector. They can be detected by another built-in detector - the annular one. The annular detector provides information in which topographic contrast of the specimen prevails. So it has been found out that angular distribution of the low energy backscattereel electrons provides a different image information. The same holds for the high energy electrons. Using the planar detector, the characteristic showing the dependence of the light gain of backscattered electrons on the atomic number for backscattcrcd electron energies of 1 - 20 keV was obtained. The characteristic shows diiTerent characters of low energy ( 1 - 3 keV) and high energy (5 - 10 keV) electrons. Measurement of the coefficient of backscattered low energy electrons is very demanding as far as the surface cleanness of investigated specimen is concerned. During the measurement the specimen must be cleaned by an ion beam. The attempt to connect

657


an ion gun to the microscope has not been successful yet, so that the obtained coefficient values are so far not accurate and reproducible. To delect the backscattered electron signal in a low vacuum SEM (ESEM) a double paired detector was designed and constructed. Its lower scintillator is simultaneously used as a pressure limiting aperture diaphragm (PLA). The diaphragm makes it possible to separate spaces with gas pressures of values of different orders and to guide a focused scanning electron beam toward the specimen chamber.

The gas pressure measurements made in individual parts of the microscope have proved the possibility of separating the microscope body with the electron optics and with the desired pressure of minimally 10"3 Pa from the specimen chamber in which the pressure was subsequently increased to a value of 10 000 Pa [2].

The YAG single crystal acting simultaneously as a scintillation detector of the backscattered electrons and the pressure limiting diaphragm with a hole of hundreds of /mi in diameter has a great advantage, due to the configuration used. It makes it possible to restrict the path lengths of backscattered signal electrons the gaseous medium and increases the detection efficiency in conditions of ESEM. The detector design allows us to use the detector also as a paired detector of backscattered electrons, which makes it possible to separately detect signals from its left and right halves. This, together with the computer image processing, gives possibility of increasing the topographic or the material contrast in the signal of backscattercd electrons for the specimens under investigation.

The function of the implemented detector is verified by direct observation of wet specimens and the specimens of insulation character that cannot be observed in classical SEMs without preceding adaptations using different preparation techniques. The results can be summarized as follows:

The specimens of insulation character which cannot be directly observed in the classical SEM, because of the occurrence of charging effects, can be observed in the ESEM in the backscattered electron mode. A gas pressure of 200 to S00 Pa in the specimen chamber seems to be optimum. At these pressures the charging effects entirely disappear and the image is fully comparable with that obtained in the classical SEM.

For wet specimens, the conditions at a pressure of 1000 Pa seem to be optimum for observation. The drying of specimens is slow and the image quality is fully comparable with that obtained at a pressure of 10"3 Pa. The limiting pressure in the specimen chamber at which the signal of backscattered electrons can still be detected is about 5000 Pa. Above this pressure the noise begins to intensively manifest itself in the image observed.

For the paired detector the systematic measurement of the signal-to-noise ratio in dependence on the gas pressure in the specimen chamber, the possibilities of obtaining topographic or material contrast in the backscattered electron signal and the verification of the detection efficiency of the upper part of the double paired detector are subjects of the experiments in progress at present.

References:

[1] AUTRATA, R.: Scanning Vol. 12, 1990, pp. 119-125

[2] AUTRATA, R. - JIRÁK, J. - SPINKA, J.: JMO, Vol. 5-6, 1993, pp. 124-126

This research has been conducted at the Dept. of Electrotechnology as part of the research project "Single Crystal Scintillation Detectors for Low Voltage and Low Vacuum Scanning Electron Microscopy" and has been supported by TU grant No. 991-A2.

658


SOURCE IMAGE INFORMATION PROCESSING

M. Klíma, E. Košťál, P . Zahradník, P. Dvorak, T. Gregor, V. Kolečkář, V. Jirásek,

J . Kolář, P . Kott , J . Rott

CTU, Fac. of Electrical Eng., Dept. of Radioelcctronics Technická 2, 1GG 27 Praha 6

Key words: information processing, sensing, ASIC design, security system, algorithmiza-tion, optical processing, pyroclcctric sensor, computer simulation

The main areas of activity covered by CTU grant No. 8124 in the years 1994-95 can be listed as follows:

A. Digital image processing algorithms for target tracking and identification. B. Assembly of a photo ASICs VLSI design lab in cooperation with Paul Scherrer Institut

in Zurich and deisgn of two VLSI ASICs with optical input. С Initial experiments in optical informcition processing - future cooperation with St.

Patrick's College, Dublin.

A. In the field of digital image processing we have continued the study of target tracking and identification initiated two years ago. Apart from original moving target detection our activity has focused mainly on moving target tracking and consequent target identification in order to achieve functionality of all blocks of a potential TV security system. Relevant experimental algorithmic and computational experience creates a sufficient background for formulation of suitable algorithms for optical processing systems. Correspondingly our effort for the last threee years has been oriented toward participation in the IEEE Carnahan Conference on Security Technology in Albuquerque, USA. Our paper (1) was accepted and published but unfortunately because of limited financial resources we could not participate personally as in the years 1991-93. Our experimental models are robust enough to dis-tiguish three basic classes of objects and to perform reliable tracking because of template adaptibility.

B. Based upon a grant from the Swiss Research Agency [2] we have started assembling a VLSI design facility for photo ASICs in cooperation with the Paul Scherrer Institut. Financed from the above mentioned grant we purchased an L-EDIT software design package from TANNER .Corp.[3], and the design of two chips has been completed. The first chip was dedicated to various CCD sensors and consequent signal processing blocks. The second one was assembled from a commuting structure for a pyroelectric sensor and from a set of simple functional blocks for signal reception and conditioning ( photodiode, voltage reference, bipolar transistor, OPAMPs etc.). A separate part of the latter chip is reserved for a design of driving circuitry for a semiconductor laser (task defined by PS1Z). All the designed structures have been simulated on a SPICE simulator. Some experiments (e.i. transistors, diodes) will help us to define more accurate simulation models. Both chips were designed for the ORBIT's FORESIGHT 2-micron CMOS process. Recently, both chips were delivered

659


and the test procedure is now in progress. All expenses have been covered by the Swiss grant [2]. From local grants a hardware upgrade of the existing computing facility has been financed. As a part of this cooperation with the Swiss Research Agency, two workshops for doctoral students have been organized in Prague, two Czech doctoral students have spent some time in Zurich. Some preliminary results have already been published [3,4].

C. In 1994 a new cooperative agreement was preliminarily reached with St.Patrick's College, Dublin, Dept. of Computer Science and Dept. of Experimental Physics with respect to research and developement in the field of optical processing systems. Based on our long term experience (1973-1990) we have begun initial selected experiments with acoustooptic signal processing units used as spatial light modulators. Our original experiments four years ago were finished with a simple АО spectrum RF analyzer and signal correlator [5,6]. According to the mutual interest of all three participating institutions new methods will be tested, e.g. optical implementation of neural networks.

A common idea joins all the three parts of the project together. Using an experimental model of a TV security system we can improve our understanding of the algorithms required for basic image processing tasks (part A). Highly efficient optical signal processing units offer very high computational power. In combination with VLSI photo ASICs used as specialized sensors with built-in signal pre-processing (part B) these units can form a highly efficient and extremely fast processor for a particular class of algorithms.

Most results have been directly applied in study courses (lectures and laboratory ex-cersises in Image Processing and Photonics).

References: [1] KLÍMA, M. - ZAHRADNÍK, P. - DVORAK, P. - AT AL.: Motion detection and target

tracking in a TV image for security purposes; Proc. of IEEE Carnahan Conference on Security Technology, November 1994, Albuquerque, NM

[2] KNOP, K. - SEITZ, P. - KLIMA, M.: Funktionsmodulc von Photo-ASICs fuer die optische integrierle Messtechnik; Contract NoJTRPJ 3038543, Swiss national Scicnece Foundation - Swiss Scientific Support for Eastern Countries, 1993

[3] GREGOR, Т. - KLÍMA, M.: Acccsible and powerful ASIC design tools and practical results of its use; EDS 94 Conference, Brno, November 1994, to be published

[4] JIRÁSEK, V. - KLÍMA, M.: Vybrané konstrukční prvky ASIC s optickým vstupem se azamiřením na 3D snímání; EDS 94 Conference, Brno, November 1994, to be published

This research has been conducted at the Department of Radioclectronics as part of the research project "Source Image Information Processing" and has been supported by CTU grant No. 8Щ.

660


NEW CONCEPT OF OPTOELECTRONIC SENSOR USING LINEAR CCD

J. Fischer, R. Šmíd

CTU, Fac. of Electrical Eng., Dept. of Measurements Technická 2, 166 27 Praha 6

Key words: optoelectronic sensor, linear CCD, pixel locator

For contactless measurement of dimensions, many types of optoelectronic sensors are used. The linear CCDs has some advantages-higher scan rate, higher resolution in one axis, lower costs, for which they are preffered to 2D CCDs, esp. in applications for measurement of length, diameter, distance, width etc.

Typical linear CCD output signal in situation depicted in Fig. 1 is described in Fig. 2. Output voltage U equals discretization of irraciiance E[W/m2] projected on CCD active area. For the experiment wc used CCD with 1x2048 pixels. The measurement value can be calculated as distance between edges in light intensity profile.

UNEARCCD dimension

Fig. 1: Measurement using linear CCD Fig. 2: Typical output signal

Simple method for evaluation of edge positions can be realized using analog comparator, which is able to distinguish two intensity levels (black and white). Unfortunately, the optical edge never has ideal shape but it is influenced by some errors i.e.:

• non-uniformity of background light • non-uniformity of photo response • errors in optical system

This makes the method relatively inaccurate, because the measurement value strongly depend on comparator level. For lowering the above listed errors several methods are used. One of thejmost important methods is photometric interpolation, which also provides sub-pixel resolution. This method is based on numerical processing of digitalized video signal in neighborhood of optical edge.

661


Until now, digital processing of videosignal was too slow because it is nccesary to search in the whole line scan for edges and then to compute edge position.

Newly designed architecture of sensor enables us to combine fast hardware edge localization and numerical processing, which is carried out only in the nearest neighborhood of edge.

н>не» linear CCD

Hi-speed A/D converter

shared video memory

digitalised data

digital comparator

сотр. level

FIFO

address of actual pixel

16-bit micro controller 80C196

RS-485 a •

RS-232

digital output

Weo memory (shared) * v dgrtalked data

FIFO memory

D/A conv.

analog output 8 bits 12 Ms

address of edge in video memory

Fig. 3: Block diagram Fig. 4: Pixel locator Sensor consists of control logic, linear CCD, vidcoamplificr, hi-spced S-bit A/D con

verter, shared videomemory (2k xS), digital comparator, FIFO memory and 16-bit microcontroller.

Control logic with comparator and FIFO memory represent the pixel locator, which serves for rough localization of optical edges. CCD output signal is adjusted in amplifier, fixed to reference level of black pixels and converted into digital form. Digitalized videosignal is stored in shared videomemory and compared with software-definable level. At the moment when the videosignal crosses the set level, the address of actual digitalized pixel is written into FIFO memory. Microcontroller may directly access to the address of neighborhood of optical edge.

The main advantage of the above described concept is high scan rate with numerical processing of optical information.

References: [1] FISCHER, J. - SEHNAL, J. - ŠŤASTNÝ, .1. - VALOUSEK, J.: Přesné měření polohy

za použiti CCD snímače a jolomclrickč metody zpracování signálu, In: sborník konference ELMEKO 88, pp. 145-14C, Znojmo 198S.

[2] ŠMÍD, 11.: Diplomová práce: Obvody optoelektronického snímacího modulu, ČVUT FEL kat. měření 1993

[3] FISCHER, .1. - ŠMÍD, R.: Optoelektronický snímač s CCD lineárním senzorem a hybridním zpracováním signálu, In: International Workshop "Measurement and Control 94", VSB - TU Ostrava, 1994

This research has been conducted at the Department of Measurements.

662

WORKSHOP !)5 ELECTRONICS & OPTICS

FIBRE-OPTIC FABRY-PEROT SENSOR FOR VIBRATION AND PROFILE

MEASUREMENTS I . Paulicka, V. Sochor, J. Stulpa

CTU, Fac. of Nucl. Sci. & Phys. Eng., Dept. of Physical Electronics V Holešovičkách 2, ISO 00 Praha S

Key words: fibre optics, optical fibre sensor, Fabry-Pcrot interferometer, optical scanning

In this paper we demonstrate the operation of a feedback stabilized quadrature phase-shifted extrinsic Fabry-Perol (FP) fibre-optic sensor for the remote detection of the amplitude and the relative phase of subnanomelcr vibrations and displacements. To provide the surface profile measurement the fibre end is laterally vibrating at a constant distance from the plane of object surface. The resolution order of 10~n m in vibration amplitude measurement was obtained. In the surface scanning regime the vertical deviations about 1 nm can be distinguished.

Fig. 1: Principal scheme of extrinsic Fabry-Perot sensor. L - laser, RC - sine-wave generator, Amp - amplifier, BS - beam splitters, D\ - feedback detektor, Dj - signal detektor, Z)3 -laser power detektor, D-Amp - differential amplifier, LI - lock-in amplifier, OF - optical fibre, С - coil, M - magnet, MT - elmag. controlled microshift table, OS - object surface, Osc - oscilloscope.

The interferometric system displayed in Fig. 1 can also be used for scanning the height profile of reflective surfaces with height differences smaller than A/4 of used radiation (A

663


= 633 nm). The fibre is fixed to a special mechanically vibrating mount driven by electromagnet, so that fibre end-face is laterally vibrating at a constant distance from the plane of object surface. The length of scanned profile was approx. 0.1 mm.

The example of intensity signal corresponding to the surface profile is shown in Fig. 2. The reference intensity level I„j is defined by the formula

/ r , / = 'max T 'in

Avhere Imax and /m;„ are the maximum and minimum intensities of interference respectively. The deviation v from ideal plane surface is given (with accuracy approx. 2%) by [4]

v= -T~-T where 27Г 2.

ДФ = arcsin / - / , rcj

'max i\ rcf

In case of proper system adjustment and small height differences the output signal modulation is linearly proportional to the surface profile. The lateral resolution of scanning measurement is limited by the used optical fibre core diameter (5 Sm).

v [nm]

lr»ln

d - O.I mm

Fig, 2: Intensity signal corresponding to the surface height profile.

Further improvements of the device arc in preparation. Substitution of the bulk beam-splitting prism by the integrated optical coupler would make the system more rigid and compact. The lateral resolution can be significantly improved by using tapered fiber end.

References:

[l] MURPHY, K. A. - GUNTIIER, M. F. - VENGSARKAR, A. M. - CLAUS, R. O.: Quadrature phase-shifted extrinsic Fabry-Pcrol optical fiber sensors Opt. Lett. 16, 273, 1991.

[2] PAULICKA, I.: PhD thesis Czech Technical University Praque, 1993. [3] UDD, E.: Fibre Optics Sensors John Wiley, New York, 1991. (journal, pages, publisher,

year etc.). [4] STULPA, J.: Diploma paper Czech Technical University Prague, 1994.

This research has been conducted at the Department of the Physical Electronics and has been snporlcd by grant projed V 324/1994 of Ministry of Education, Youlh and Sports of Czech Republic.

664

Section 13

BIOMEDICAL

&

ENGINEERING

WORKSHOP 95 BIOMEDICAL ENGINEERING

CARIES SELECTIVE ABLATION BY PULSED UV EXCIMER LASER

P. Gavrilov, A. Jančárek, M. Kozlová, P. Zima, M.D.

CTU, Fac, of Nucl, Sci, & Phys, Eng,, Dept. of Physical Electronics V Holcšovičkách 2, 180 00 Praha 8

Key words: excimcr laser, UV light, dental treatment, ablation thresholds, dental decay and removal

Introduction. The aim of the study was to find conditions for selective ablation of carious dentine. Ablation thresholds were studied for both healthy dentine and carious dentine. By means of a piezoelectric detector ultrasonic waves generated by ablation and subthreshold thcrmoclastic mechanisms were detected.

Since the 60s lasers have been used in dental medicine in an attempt to remove carious lesions [1]. Early investigations with a pulsed ruby laser demonstrated in principle that selective ablation of dental decay is possible on a microscopic level without too much damage of the structure of the healthy dentine [2]. On the other side, investigations using near UV laser radiation for dental treatment and absorption data collecting of dental hard tissues began at the end of the 80s [3]. Optoacoustic techniques [4, 5, 6] were applied to determine the ablation thresholds of healthy and carious lesions.

Experimental procedure. Extracted teeth from 11 human patients were transferred directly into 1% sodium chloride solution. Teeth were segmented in a different sizes (minimally possible) and determination of ablation threshold of healthy dentine and carious lesions was carried out in more than 100 locations.

The optoacoustic approach was used to determine ablation thresholds of carious lesions and healthy dentine at a fixed wavelength (308 nm, XcCl excimcr laser). This method determines (shock wave) pressure as a function of energy density. The detected signals are either due to acoustic waves resulting from linear photoacoustic processes below the ablation threshold or to the physical removal of material above the ablation threshold [5, 6]. The experimental setup is illustrated in Fig. 1.

I ENEMY K M I «ттеиилткш »*ит« IEN» mcinm

""•E3- -M -л-0

•I PMOTMClMTfC

OETiCTOH JOI11.MITEP '

I "'oso. с

Fit liEIMSWMENWI. SETUP

667

! | EXCIMER ! ! LASER


Results. The onset of ablation becomes evident with a sudden rise of optoacoustic signals and depends strongly on energy density of radiation striking on the dentine. Apparently the ablation threshold of a carious lesion largely depends on the nature of the dentine decay. The ablation threshold is from 0.1 J/cm2 for "dark" stained carious lesions up to 0.5 J/cm2

for "white" stained carious lesions. A sudden increase in the slope of optoacoustic signals indicating ablation threshold of healthy dentine appears to be by a factor greater minimally of 2 than for carious lesions. Our results are in a accordance with results (absorption data and measurements) presented in [3] although of their slightly difference wavelength used (355 nm).

The authors gratefully acknowledge professional support and advice of Professor M. Vrbová.

References:

[1] GOLDMAN, L. - HORNBY, P. - MEYER, II. - GOLDMAN, В.: Impact of the Laser on Dental Caries, Nature 203, p. 417, July 1964.

[2] SCHULTE, W. et al.: Laser eject on dental substance Dtsch. Zahnarztl. Z. 20(4), p. 289, April 1965.

[3] HENNIG, T. - RECHMANN, P. - PILGRIM, С - KAUFMANN, R.: Basic principles of caries selective ablation by pulsed lasers Proceedings of the Third International Congress of Lasers in Dentistry, Salt Lake City, Utah, USA, 123-124(1992).

[4] PATEL, С. - ТАМ, A.: Applications of photoacoustic sensing techniques, Rev. Modern Phys., Vol. 18, No. 2, p. 381, April 1986.

[5] GORODETSKEY, G. et al.: Calorimetric and acoustic study of ultraviolet laser ablation of polymers," Appl. Phys. Lett. 46(9), p. 828, May 1985.

[6] PETZOLD, S. et al.: Surface laser demage thresholds determined by photoacoustic deflection, Appl. Phys. Lett. 53, p. 2005, November 1988.

This research has been conducted at the Department of Physical Electronics as part of the research project "Application of UV laser radiation for dental treatment" and has been supported by CTU grant No. 48205.

668


LASER-INDUCED FLUORESCENCE OF HUMAN BLOOD

P. Šurý, P. Poušek, M. Vrbová

CTU, Fac. of Nucl. Sci. & Phys. Eng., Dcpt. of Physical Electronics V Holešovičkách 2, ISO 00 Praha S

Key words: blood, LIF, laser-induced fluorescence, fluorescence spectra

Laser-induced fluorescence (LIF) is a useful tool for nondestructive testing of materials (e.g. detection of atmospheric pollution). LIF can be also used to investigate biological objects, e.g. the state of health of plants [1].

We try to use LIF in medicine for the diagnostics of human health. The state of health is reflected by all parts of a biological organism, but not all of them

are suitable samples for LIF. The laboratory sample should be stable in time, stable under the illumination, etc. Our experiment started with blood.

Samples of cause bring problems with coagulation in the air and high absorption of light. The problem of coagulation has been solved by using suitable solutions (e.g. heparinum natricum, natrium citricum, etc.). The absorption problem has been overcome by dilution of blood in some suitable solution: heparin (heparinum natricum), clean water, isotonic solution, etc. Solutions without fluorescence in visible part of spectrum are preferred.

In our experiment the blood sample is excited by unfocused radiation of XeCl excimer laser (308 nm, 15 ns, 10 Hz, 80 mJ, energy density at the sample 0.3mJ.cm~2). The analysis of fluorescence spectra is produced by dual grating monochromator GMD 1000, photomul-tiplier RCA 8852 with S20 photocatode, and the signal is proceed by electronics circuits. The output signal is proportional to the integrated fluorescence signal for 6 microsecond. The spectral sensitivity of this receiver was determined by two calibration steps providing information about the relative spectral sensitivities (using black body radiation), and about the absolute sensitivity (using the He-Ne laser with the known output power).

Each sample of the healthy and sick blood was measured three times (Fig. 1 and 2). These spectra have two parts: a blue part caused mainly by the fluorescence of solution (isotonic solution) and cuvette, and a red part appropriate to the blood component. The spectra were smoothed using the Fast Fourier Transformation technique. The maxima and minima were obtained by curve differentiation. This process resulted in two maxima and one minimum in the red part determined which corresponded to the blood. Due to the errors during the measurement and analyzing, the peaks are not determined sharply: 596 nm and 656-658 nm for healthy blood (Fig. 1); 600-604 nm and 654-660 nm for sick blood (Fig. 2). The ratio of 600nm peak/658 nm peak is 1.0-1.2 for healthy blood and 1.3-1.5 for sick blood.

The differences between healthy and sick blood are evident. But, before the LIF of blood can be used as a detection tool of illness, the relations between the shape of fluorescence spectrum and the type of illness should be carefully studied and correlated with common medical diagnostic procedures.

References: [1] KRAJÍČEK, V. - VRBOVÁ, M.: Laser-Induced Fluorescence Spectra of Plants, Re

mote Sens. Environ. 47:51-54 (1994)

669


This research has been conducted at the Department of Physical engineering as part of the research project "Laser-Induced Fluorescence" and has been supported by a grant of IGA MZCR.

1 2500 f g 2000 -i-1500 f

3000

1000 500

4 1 1 1 1 1 1 1 1 1 1-0 350 400 450 500 550 600 650 700 750 800

Wavelength [nm]

Fig. 1: Spectra of the healthy blood

• 1500

e ^•1000

2000

0 i " * r i — i — i — i — i — i — i — i — i — i — i — > — i — i — н ^ * =

350 400 450 500 550 600 650 700 750 800 Wavelength [nm]

Fig. 2: Spectra of the sick blood

670


Er:YAG LASER FOR OPHTHALMOSURGERY

H. Jelínkova, J. Pnšta*, K, Hamal

CTU, Fac. of Nticl. Sci. & Pliys. Eng., Dept. of Physical Electronics V Holcšovičkách 2, 180 00 Praha 8

*Military Hospital, 1G9 02 Prague G

Key words: Er:YAG laser, ophthalmology, laser ablation

Solid state lasers make possible rapid technological advances in medical applications by virtue of their wavelength and temporal mode versatility, convenience, relative compactness, and portability. Laser applications in ophthalmology date fully 30 years back, but laser radiation was used mainly for retina coagulation (ruby laser, argon laser) and later for iridectomy and capsulotomy (Nd:YAG laser). The latest studies indicate that it is possible to use laser radiation of specific wavelength for the surgery of anterior segment of the eye [1,2,3,4]. The wavelength of radiation providing a really remarkable ablation effect of that tissue is A=2.94 /mi (EnYAG laser) and A=0.308 /tm (excimer laser). Radiation wavelength A=2.94 /ťm coincides precisely with the peak of water absorption spectrum. Therefore, the photothermic ablation threshold for irradiated tissue by that radiation is lower than for radiation of other wavelengths.

The area of our interest was: the generation of crater in lens like materials inside the eye's lens and cutting of the cornea tissue (in vitro) with the help of mid-infrared laser radiation (A=2.94 /tm).

For the experiment the EnYAG - ophthalmic laser system delivering S00 mJ maximum energy in 200 /ts long pulses was designed and constructed. The laser resonator was formed by plan-parallel dielectric coating mirrors with the rear mirror reflectivity ~100% and the output mirror reflectivity 67%. The length of the resonator was 28 cm. A crystal of EnYAG with a diameter of 7 mm and 120 mm long was placed inside a silver coated one ellipsoidal cavity and pumped by one linear xenon flashlamp. The crystal, flashlamp, and pumping cavity were carefully cooled to stabilize the work of EnYAG oscillator [5]. The laser was working in a free running mode with the repetition rate of 1 Hz. Laser radiation was transported by delivery arms and focused on the tested tissue with a Cal?2 lens (f=55 mm) to increase the radiation energy density.

Cadaverous human eyes were placed into a special stand and tissues of the anterior eye segment were treated by EnYAG laser radiation. Direct external interventions were realized, in situ, and photoablation was done in sealed anterior chamber. The affected tissue was prepared for further investigation with raster electron microscopy.

From the first results follow that it will be possible to apply the EnYAG laser radiation in mid-infrared region in eye surgery - mainly in paracentesis and sclerostomy. Good results can also be reached with therapeutic scleral or corneal ablation [6]. Er:YAG laser radiation seems to be effective also for photoablation of cataractous nucleus where it would have a similar effect like ultrasound phacoemulsification.

671


References: [1] BENDE, T. - SEILER, T. - VVOLLENSAK, J.: Plwtoabtation mil dem Er:YAG Laser

Okularen Geweben Fortschr. Ophthalmol., SS, 6-12, 1991 [2] KAHLE, G. - STADTER, II. - SEILER, T. el al.: Gas chromatographic and mass

spectroscopic anahsis of excimer and erbium, yttrium aluminum garnet lastr^ablatcd human cornea Invest.Ophthalmol.Vis.Sci., 33, 2180-2184, 1992

[3] KAHLE, G. - DAQUN, X. - SEILER, T. et al.: Wundheilung der Komea von Neuweltaffen nach flachigcr h'eralektomie; Er YAG Excimerlaser. Fortschr. Ophthalmol., 88, 308-385, 1991

[4] TSUBOTA, K.: Application of Erbium YAG laser in ocular abblation Ophthalmologica, 2П0, 117-122, 1990

[5] PASTA, J. - JELÍNKOVA, H.: Er YAG laser pholoablalion of eye tissues Proc. of XXVII International Congress of Ophthalmology, Toronto, Ontario, Canada

[6] JELÍNKOVA, H. - HAMAL, К. - PROCHÁZKA, S. - a dal.: Laser YAG/YAP:Er Cs. cas. pro fyziku, 42, 57—65, 1992

This research has been conducted at the Department of Physical Electronics as part of the research project "Er:YAG Laser for Ophthalmosurgery" and has been supported by CTU grant No.8207.

672


ACOUSTIC RESPONSE MEASUREMENTS OF HUMAN

CENTRAL AIRWAYS Z. Škvor, F. Kadlec, K. Šnajdr

CTU, Fac. of Electrical Eng., Dept. of Radioelectronics Technická 2, 166 27 Praha 6

Key words: acoustic rhinometry, acoustic area distance function, pulse response measurement, acoustic airway impedance, acoustic reflections from airways

Acoustic impulse response measurements are methods for determining the individual cross-sectional area functions of human central airways. Acoustic methods can be used to study the supraglottal oral cavity, the geometry of nasal cavity, pharynx and tracheal cross-sectional areas, and the central airway in lungs. By applying acoustic reflection measurements, some pathological and physiological changes can be diagnosed.

This paper deals with an impulse technique for measuring responses of human central airways in physical models. An experimental model of human central cavities has been designed and created for acoustic reflection measurements.

Acoustic reflection measurements are based on the determination of the input acoustic impedances of human airways. Using digital signal processing we can define the acoustic impedance z(w) as the ratio of the finite Fourier transforms of sound presure p(t) and acoustic volume velocity w(t)

z ( w ) = (^i T ? ' ( í ) e " i w í ( i í ) ' (?r , , , ( ť ) c " j W d ť ) ' (i)

where T is the time interval in which p(t) and w(t) are included [1, 2]. Consider the propagation of a presu re impulse in the acoustic system shown in Fig.l.

An acoustic impulse travels along a tube with characteristic impedance Zo. The wave encounters the impedance discontinuity at x=X], ti = Х\/с. A portion of the wave will be reflected in the oposite direction, and the rest of the signal will be transmitted into the model of airways of characteristic impedance Z\. The model of airways has multiple discontinuities. The impulse response of the complex system is given by

A(0 = Eft(OÍ(í-*fc), (2)

where Fjt(i) are the reflected parts of the signal; n is the number of discontinuities and tk — %k/c,%k яге the distances of discontinuities from the position of the microphone. Reflected wave Pr(t) is related to the incident wave P;(0, by convolution

Pr(t) = f Pi(r)h(t - T)dr. (3) Jo

The impulse response can be extracted from the Fourier transform of the convolution (3)

673


Pr(w) = Р , М Н И . ('D The impedances z(w) and cross-sectional areas of the structure arc calculated from P;(w) and P r(w).

The experimental measurement setup is shown in Fig. 1. The source of the acoustic pulses is the electroacoustic transducer fed with short pulses from the generator via amplifier. The transducer creates acoustic pulses which propagate down the wave tube [3]. Acoustic pulses pass the microphone and enter the physical model of human central airways. The analog signal from the microphone is amplified, digitized and processed [2].

Generator trigger

Amplifier

Dig.Signal J Processing

Microphone

phonel ilifier I

Vlicrophonc| Amplifier Computer

Model of airways (lungs)

D. Transducer Tube *o=

Fig. 1: Block diagram of equipment for acoustic reflection measurements.

During the first phase of the project we concentrated our efforts on the theoretical analysis of impulse acoustic measurements of human cental airways, and we carried out basic measurements on models. In the second and final phase we intend to replace the method using impulse measurements with the MLSSA method and to apply the latter method in clinical practice.

References: [1] Kadlec, F.: Impulse Measurement of Impedances of Ultrasonic Transducers. In: 2nd

Postgraduate Students Conference on Acoustic. Praque, CTU, 1993, p. 67-70. [2] KADLEC, F.: Impulse Response Measuremenl of Ultrasonic Transducers. Journal de

Physique, Colloque C5, Suppl.III, Volume 4, 1994, p. 295-298. [3] SKVOR, Z. - KADLEC, F. - BRUNEAU, A. M. - LOTTON, P.: Piezoelectric Trans

ducer with Monoaxially Oriented Piezopolymer Diaphragm. Acta Polytechnica, Czech Technical University, Praque, Vol. 32, 1992, No.l, p.59-64.

[4] HILBERG, O. - JACKSON, A. - SWIFT, D. - PEDERSEN. 0.: Acoustic rhinometry. evaluation of nasal cavity geometry by acoustic reflection. Journal of the American Physological Society, 1989, p. 295-303.

This research has been conducted at the Department of Radio electronics as part of the research project "Acoustic pulse methods and their medical applications" and has been supported by CTU grant No. 8197.

674


FORMALIZED RESTORATION AND ANALYSIS OF

BIOMEDICAL IMAGE DATA

J. Jan, P. Kilián

TU Brno, Fac. of Electrical Eng. and Сотр. Science, Dept. of Biomedical Eng. Purkynova 91 A, 612 00 Brno

Key words: image restoration, ultrasonography, Wiener filtering, speckle reduction

The ultrasonic imaging suffers from high specific noise (speckles) content and low resolution especially in lateral direction. Many trials were published to improve the quality of the image by more or less formalized filtering, e.g. [1-3] but the results were not too convincing. There arc severely unfavourable properties of the ultrasonic imaging that complicate such a restoration, primarily nonlincarity and anisoplanarity of the imaging process and non-additive nature of the speckles. So far three distinct approaches as compared in [5] were applied to the problem, namely averaging of several images with diversified speckles, weighted and modified median filtering and most formalized of them, Wiener filtering. The direct application of the Wiener filtering is nevertheless quite ineffective due to the mentioned obstacles and also due to the high variety of the useful- as well as noise components of the images that complicates the estimates of the power spectra. A relatively successful modification of Wiener filters realized via frequency domain is the subject of this contribution.

Our restoration is based on a model of the distorted image containing a convolution of the original undistorted image with the point spread function (PSF) of the wobbling crystal scanner, additive noise representing the speckles and the superimposed nonlinearity reflecting primarily the envelope detection of the radio frequency signal to obtain the video signal and logarithmic amplification used for dynamic range suppression. It has been proven in previous work [4] that the most suitable form of data is the raw (format non-converted) data matrix where the PSF is isoplanar on most of the image area. The filtering uses, in principle, the well known form of the Wiener filter as described in frequency domain

M(u,v) = [l///(ti,u)].[(5„(u,i>) - Snn(u,v))/Sgg(u,v)] where II(u,v) = DFT{PSF) is the frequency transfer function of the imaging system, Sgg is the (average) power spectrum of the distorted images and Snn is the (average) power spectrum of the noise.

The first factor on the right hand side is an approximation of the direct inverse filter. As the estimates of the system's PSF are rather imprecise, they must be normalized, averaged and smoothed by a suitable filter. The obtained pure inverse filter l / / / (« , v) is totally useless due to the extreme values for frequencies where the transfer function is nearly zero. Thus a nonlinear modification of the filter is vital for successful processing. The modified filter preserves the sharpening properly surprisingly well while keeping the narrow band artificial noise at a reasonable level, probably thanks to the completely preserved phase information in the filter transfer. The second (Wiener) factor serves primarily only to distinguish between speckles and useful image content and to suppress the former. Estimates of the power spectra arc based on manually selected subframcs containing cither typical areas of noisy

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image with expressed anatomic structures, or those of almost only pure noise, respectively. The high importance of nonlinear modifications, applied even to the Wiener factor, must be emphasized.

Frequency domain filtering suffers from the finite size of the transformed matrices. To remove this effect completely would require to use several times larger matrices which is rather impractical in the available computing environment. Instead, it proves acceptable to use s.c. soft-framing.

The derived filter based on spectral estimates of frames taken from a set of images of different objects (a number of heart views, liver, billiary duct and gallbladder, hepatic venes, kidney) was then applied to all the images without any further image specific modifications.

Considering the results obtained by filtering via frequency domain, it can be concluded that appreciable degree of speckle suppression was achieved without almost any loss of resolution. The results were compared with images improved by other published methods. They were found to be almost as good as those produced by averaging with artificially diversified speckles and better than the products of adaptive median filtering. Furthermore, averaging is rather impractical because of the very demanding data gathering involved, while median filtering though rather simple shows certain artefacts reflecting the size and shape of the windows used. The main results of the last period are the derivation of a generally applicable filter independent of specific image content and routine application of the filtering to real medical images enabled by cooperation with medical institutions. The processing speed using PC environment has been speeded up so that it is now sufficient for off line processing of individual frames.

It should be mentioned that the grant project is wider and covers several other imaging modalities too; these parts are presently in the initial stage of providing the necessary instrumentation and data.

References: [1] ROBINSON, D. E. - WING, H.: Lateral dcconvolulion of ultrasonic, beams. Ultrasonic

Imaging, vol. 6 (1984), pp. 1-12 [2] GEHLBACH, S. M. - SOMMER, F. G.: Frequency diversity speckle processing. Ultra

sonic Imaging vol. 9 (1987), pp. 92-105 [3] LOUPAS, T. - MCDICKEN, W. N. - ALLAN, P. L.: An adaptive weighted median

filter for speckle suppression in medical ultrasonic images. IEEE Trans. CS vol.36 (1989), no.l, pp. 129-136

[4] JAN, J.: Experimental restoration of ultrasonic tomograms by modified Wiener filters. Archives of Acoustics, vol.17 (1992) no.l, pp. 53-68

[5] JAN, J. - HALUZIKOVA, J. - KILIÁN, P. et al.: Comparison of different appivaches to suppress speckles in ultrasonic tomograms. Proc. 5th int.conf. CAIP'93, in Lecture notes in computer science 719, Springer 1993, pp. 657-663

[6] JAN, J. - KILIÁN, P. - KUČERA, D.: Routine restoration of ultrasonic tomograms by modified Wiener filtering. Proc. int. conf. BIOSIGNAL'94, Brno 1994, pp. 54-56 This research has been conducted at the Department of Biomedical Engineering as part

of the research project "Formalized restoration and analysis of biomedical image data" and has been supported by TU grant No. C30/94-

676


MEASUREMENTS OF SOLID PARTICLES FLOW

K. Zehnula, P. Benes

TU of Brno, Fac. of Electrical Eng., Dept. of Automation and Measurement Eng. 2, Božetěchova Str., 612 66 BRNO

Key words: acoustic emissions, flow, solid particles flow

Flow measurements arc among the most difficult ones because the measured medium can occur in various physical states, which complicates the measuring procedure. They are mainly temperature, density, viscosity, pressure, multi-component media (liquid-gas, solid-gas), the type of flow, etc. The choice of the method is further directed by specific requirements for the flow meter, e.g. a wide measuring range, minimum loss of pressure, the shortest possible recovery path, a sensor without moving parts, continuous operation of the sensor, etc. That is why about 60 measuring methods have been developed to meet the increasing demands on laboratory and industrial measurements of flow of gases, liquids, vapours and solids in one-phase or multi-phase form.

Of interest are methods of measuring two-component media, e.g. solid particles in gas. Some methods exploit the various effects of individual particles, e.g.:

1. Shielding of light flow 2. Force effect

a) triboelectric effect b) acoustic emissions

These methods have been employed for measurements of flow, flow rates and granulo-metric structure (rate of occurrences of particles of a specific size).

The principle of the method making use of acoustic emissions is that the particles are carried at a constant velocity by a carrier gas. In the flow channel there is a partition against which the particles strike. The impact generates a pressure deformation wave - an ultrasonic signal is emitted.

By means of an ultrasonic emission transducer this signal is transformed into an electric signal. As the signal from the transducer is rather weak, it must be first amplified and then further processed for evaluation. The signal has the shape of pulses. It is possible to measure its amplitude or rate of pulses. Amplitude analysis can yield information on the granulometric structure (the rate of occurrences of particles of a specific size).

The primary signal of ultrasonic emission has therefore a pulse character. The pulse length may be less than 100 ns. At the present time ultrasonic vibrations with amplitude 10-14 m can be measured. With a larger number of emission events a continuous signal originates. However, it is rather difficult to construct a sufficiently sensitive wide-band ultrasonic emission transducer.

Measurements of the flow rate have been tested using an apparatus for dosing powder

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graphitization inoculation material for inoculating grey cast iron in the foundry. Block diagram of the meter is in Fig.l.

A Л

—1 fe-

Fig. 1: Block diagram of the flow meter

The partition (incursion block) is inserted in the flow channel with the sensor (1) tightly attached to it. Electric signal from the sensor (1) is brought to amplifier (2) and further through filter (3) to amplitude meter (4). The filter suppresses strongly spurious signals under 40 kHz. Rate meter (5) is connected in parallel behind the filter. The partition inside the flow channel is of the shape of rod. with cylindrical cross-section. Other shapes have been tested (inclined plate, bent pipe, etc.).

The above described method of measuring the flow of solid particles in a carrier gas represents a contribution to the so far used techniques. Measurements can be carried out even at high temperatures and the only restriction is the Curie temperature of the piezoelectric material of the sensor. The sensor is simple in construction. The whole meter, e.g. for measurements of dustiness can be manufactured in a portable version, Palcnt application has been filed.

References:

[£] KAISER, J.: Schallcmisionsanalyse Technishes Mcsscn, 47 (1980), No 11 and 12 (in German)

[2] ZEHNULA, K.: Meter of Dustiness Patent application PV 863-94 (in Czech)

This research has been conducted at the Department of Automation and Measurement Engineering as part of the research project "Sensors Technique and Measurement of Nonelectrical Quantities " and has been supported by TV of Brno, Grant No. B25.

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IMPEDANCE TOMOGRAPHY J. Vašína, J. Lepká, T. Macho

TU, Fac. of Electrical Eng. k. Computer Science, Dcpt. of Control and Instrumentation Božetěchova 2, 612 00 Brno

Key words: tomography, image reconstruction, inverse problem, finite element method

Electrical impedance tomography is a technique for producing tomographic images of the distribution of electrical resistivity within electrically conducting objects. The data used to reconstruct images of resistivity distribution are measurements of the voltages developed on the surface of the object when various patterns of current are passed through the object.

The impedance tomography system used consists of 32 electrodes connected to the vessel, a data collection system and an image reconstruction computer. Electrodes are placed into the vessel wall in order to make measurements of the distribution of electrical resistance within an image plane. This is performed by injecting an AC current via one pair of adjacent electrodes and measuring the voltage values at all other pairs of adjacent electrodes. The measured values, whose amplitude depends on the resistivity distribution in the vessel, are sent into a computer and a cross-sectional image of the resistivity distribution is reconstructed using a suitable algorithm. The computer also provides control signals for the data collection process.

In the data collection process, first the current is applied through electrode pair 1-2. The current flows through the circular cross section, with its intensity maximal at the periphery near the current injecting electrodes and diminishing rapidly towards the opposite side. The voltages are measured between the electrode pairs 3-4, 4-5, 5-6, ..., and 31-32. All voltage measurements are independent. Then the current-driving electrode pair is changed to 2-3 and voltages arc measured similarly between all other adjacent pairs of electrodes. Next the current-driving electrode pair is rotated through 3-4, 4 -5 , . . . , 31-32.

Modelling of the resistivity distribution can be treated as an electric field problem and can be characterised by Poisson's equation

div(i grad U) = 0 (1) P

with boundary conditions -j£ = /0 on 6A and U = Uo on 5A, where p and U are the resistivity and voltage distributions within the region studied. Co and /o are the voltage and current density at the boundary region 6A.

In impedance tomography we use 50 kHz currents to map the impedance distribution. Using high frequency currents is safe and results in small electrode contact impedance.

The forward problem is to determine the voltage values for a known resistivity distribution. Since we cannot solve the forward problem for an arbitrary resistivity distribution anlytically, we have to use a numerical technique — Finite Element Method (FEM). To obtain an FEM solution, the region is divided into triangular elements. The resistivity in each element is homogeneous and isotropic. The discretization process converts the continuous problem into a problem with a finite number of unknowns by expressing the unknown field variables (voltages) in terms of certain interpolation function within each element.

The solution of the inverse problem can be performed numerically using direct or indirect techniques. Linear approximations of the non-linear problem are used. Two different

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WORKSHOP 05 HIOMEDICAl, ENGINEERING

reconstruction algorithms have been applied — the fnst filtered bnekprojoefcion method and the Newton-Rnphson method.

The technique used in the first one is referred to as backpi'ojection since the potential difference on the surface is bnckprojeclcd into a resistivity value in the area between the two cqiiipotential lines, Namely,

[I'Dlmrmurcil /n\ РЫсмШЫ = Pinilittl juriM , , , > 1 \*i

\ui))erpcetril

where Up is the potential difference between two cquipolcntial linos. Initially, the region is assumed to have homogeneous resistivity for which the potential differences at the electrodes arc calculated using analytical techniques. Secondly, the values of p are averaged over the entire image after all projection angles have been calculated. The spatial resolution is quoted as approximately 10% nnd the resistivity contrast is better than 20%,

The Newton-Raphson algorithm is so called because it makes extensive use of the Newton-Raphson iterative minimization algorithm to solve the inverse problem. The overall function of this reconstruction algorithm can be summarized by the following segment of the mcta-codc:

Guess initial resistivity distribution for the whole region REPEAT

Enter resistivity values into the finite element model Solve the forward problem Compare solution of the forward problem to the actual values producing error value Update resistivity distribution

UNTIL (error value <= predefined limit) Optimal performance of the Newton-Rap'nson algorithm, i.e. in iterating quickly to

a low error value, depends largely on the initial guess of the resistivity distribution. If the guess is poor, the algorithm may not iterate towards the correct solution. In practice, however, this reconstruction algorithm, in comparison to the backprojection, is very slow,

The core of the software tool that facilitates the development of image reconstruction algorithms is the finite element model of the vessel, which is implemented in C++ language and runs on a 4SG or Pentium based PC under the Microsoft Windows operating system.

References: [1] WEBSTER, J. G.: Electrical Impedance Tomography, pp. 76-157. Adam Hilger,

Bristol 1990, [2] PRESS, W. II. - FLANNEHY, B. P. - TEUKOLSKY, S. A. - VETTERLING, W. Т.:

Numerical Recipes. The Art of Scientific Computing, pp. 28-84. Cambridge University Press 1986.

[3] SCHWARZ, II. R.: Finite Element Methods, pp. 13-2G1. Academic Press, London 1988.

This research has been conducted at the Department of Control and Instrumentation as pari of the research project "Impedance Tomography" and has been supported by TU grant No. D 27/93.

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PHOTOELASTIC INVESTIGATION OF THE EFFECT OF TOOTH SPLINTING

ON DURABILITY OF A SET OF TEETH M. Censký, D. Jnndeková, P. Fajman,

P. Konvalinka, В. Patzák

CTU, Рас. of Civil Eng., Dept. of Structural Mechanics Tlmkurova 7, 166 29 Praha 6

Key words: pliotoclasticity, tooth splinting

Dentists in their everyday practice have to often decide, which kind of dentures to choose for repairing a damaged set of teeth. The requirements of patients often does not correspond with the state of the set of teeth and its tooth socket. In order for the dentist to be able to base his choice not only on his experience, but also on particular results of bioincchanical research, wc have come up with a solution with the help of a model method - photoclasticity - the influence of the tooth splinting of a single set of teeth in a state of stress, both teeth and alvcol with different levels of atrophy of alvcol. The suitability of the use of Photoclaslicity is given partly with its objective and intelligibility of results also for people of non-technical professions. This is partly due to the possibility to watch directly the influence of a changing factor on the stress state of the whole area of the model.

The investigation was done on a model from tried, optical sensitive material, i.e. epoxy resin. On the model, in scale 5:1, was taken the row of lower teeth from the third to the seventh, at first in the connected crown part, In the root part, it was in equidistance 1.5 mm, representing the thickness of periodontium 0.3 mm, made foundation, representing the jaw bone with an alveoral protuberance, also from epoxy resin. The 1.5 mm gap was filled with dentaflex. The investigation of stress distribution and its concentrations was executed for five different kinds of loading corresponding with various types of stress on a set of teeth during biting. At first, teeth 6 and 7 were loaded, secondly teeth 4 and 5, thirdly 5 and 7, fourthly only tooth 6 and fifthly teeth 3 and 4 were loaded. The same total loading force was chosen for all cases, i.e. 1000 N. It was not necessary to detcrmin exactly the intensity in accordance with the theory of model similarity, while the sense of investigation was in comparison with successive variants and not determination of absolute stress values.

Snaps of stress patterns of whole and half orders were taken for five given cases of loading. Then there was with cut number 1, separated teeth 5 and 6 and for the same five cases of loading snaps of isochromatic lines of whole and half orders were again taken. Next there was with cut number 2 separated teeth 3 and 4 and with cut 4, teeth 4 and 5, so that in the concluding phase the model was composed of five isolated teeth. Always after executing the next cut, stress patterns of whole and half orders for all five cases of loading were taken down.

The measurement was provided on photoeJasticimetr PMB 52. Stress patterns of zero orders were determined in white, circular polarized light. Further stress patterns of whole and half orders were determined in monochromatic sodium light, also circular polarized. Optical sensitivity of used model material was K=1.36 MPa.

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In the next part of the investigation the same model was made with the only difference being that from the lower part, in which the investigated part of the set of teeth was set, and the upper 1/3 was milled away. This represents the state of atrophied alveole. This state is usual for patients of the age of about fifty years, naturally with individual differences. For a such modified model the same way of investigation was used as for the preceding one. It means the procedure from the connected row of teeth to five isolated teeth.

We have made the evaluation of the effect of abutment tooth splinting simply through successive determination of the highest stress values for particular cases of loading in points of significant concentrations, noticeable on photographs of stress patterns. We have observed changes of stress values due to successive removal of connections, which represents abutment tooth splinting. Therefore the solved problem represents the complicated form of the state of stress, executing of another cut sometimes comes about and also to stress drop, but mostly stress values of splinted models are considerably lower than for non-splinted ones. It is necessary to realize, that the highest stress value is always due to bending, not to pressure, and by atrophied alveole the arm of force decreases. It does not mean, that the case with atrophy changes is more favourable - it is self evident, that in this case the teeth are more inclined to tear up.

type of loading

1 2 3 4 5

1 2 3 4 5

without atrophy changes maximum stress

without tooth splinting

6.5 9.S 9.0 9.1 9.5

maximum stress with tooth splinting

3.3 6.0 2.1 3.0 6.0

willi atrophy changes to 1/3 9.5 11.0 7,5 7.5 11.0

6.0 4.0 2.2 2.4 7.5

stress reduction

48% 3i>% 77% 67% 37%

36% 63% 70% 68% 32%

Tab. 1: A summary of maximum stress values without and with tooth splinting and stress reduction in %

Values given in tab. 1 show, that for incidental choice of various loading ranges, there is a decreasing of stress due to splinting from 32 to 77 %. This is a quantitative expression of generally acknowledged reality. Even if the decreasing of stress seems to be numerically and approximately the same for alveloar protuberance, both without atrophy changes and with changes.

References: [1] MILBAUER, M.: Fotoelasticimetrie a její použití v prazť SNTL Praha 1953

This research has been conducted at the Department of Structural Mechanics as part of the research project "Experimentální výzkum problémů stomatologie" and has been supported by CTU grant No. 2023.

682


APPLICATION OF TACTILE SENSOR CARPET FOR PRESSURE DISTRIBUTION MEASUREMENT

J . Volf, S. Holý*

CTU, Fac. of Mechanical Eng., Dept. of Electrotechnical Engineering Technická 4, 166 07 Praha 6

*CTU, Fac. of Mechanical Eng., Dept. of Elasticity & Strength of Materials Technická 4, 166 07 Praha 6

Key words: pressure, measurement, tactile, sensor, transducer, biomechanics

When examining in medicine one is using an ever greater number of objective methods based on measuring of physical quantities. For orthopaedics, prospectively for further branches in medicine [1] measurement of pressure distribution between the sole and the defined pad is used.

Problematics was mentioned in [2]. For verification of practical use of transducers with conductive rubber measuring device, having the rubber layer of the thickness of 0,5 mm, was designed and tested. Producer of this conductive rubber layer is Yokohama Rubber Co., Ltd (Japan) [3]. Relation between the resistence changes and the loading force of the pressure acting on the area of the electrode having 3 mm diameter is given in the fig. 1. These dimensions are relevant the relations of the designed transducer with large measures (400 x 300 mm) appointed for measuring of pressure distribution in biomechanics.

50 100 200 300 Fig)

Fig. 1:

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Practical experience was obtained by the force transducer, when using in [2] mentioned transducer PTS 1.4, which was used in medical praxis for rehabilitation. Limits of fatigue were determined on the base of the measured pressure betweem loaded muscle of the trained limbs and the transducer and the subjective feelings of the patient. At the first flag of fatigue in the loaded muscle pressure changes between skin in the area of the examined muscle and the prestressed transducer arise [4]. Overloading is not exceeded and rehabilitation is going optimally and in such a way we get a quicker curing. The measurements were carried out in the Faculty Hospital in Košice (Slovakia) with the technical support of the Technical University in Košice [5].

In the last period there were solved problems of transducer sensitivity, parasite influence as temperature and number of loading cycles on the time stability of transducer characteristics as well as distribution and measures of loading areas in the matrix of lthe transducers having large measures and the total configuration, taking in the account biomedical applications [6], operational needs and technology procedures by producing. Developing of the transducer is realized in cooperation with the weight scale producer TONAVA Ltd. Úpice.

Simultaneously applications for other branches [7] have been searching.

References:

[1] BAUMANN, W. - KRABBE, B. - PARK AS, K.: The Application of ln-Shoe Pressure Measurement in the Controlled Therapy of Diabetic Pacicnts Proc of IMEKO/GESA Symposium "Risk Minimization by Experimental Mechanics", Duesscldorf April 1992 pp. 413-419

[2] VOLF, J. - HOLÝ, S.: Pressure Distribution Measurement by Means of Tactile Sensor Carpet Proc CTU Seminar 94, Part C, pp. 61-62

[3] Technical dokumentation of the conductive rubber CS57-7RSC Yokohama Rubber Co. Ltd.

[4] VOLF, J,: Design and technical documentation of the transducer of muscle activity nonpublished technological documentation, Prague 1993

[5] ZIVCAK, J.: Measuring of muscle activity and its fatigue limits during rehabilitation ( Meranie aktivity svalu a jeho únavy v priebehu rehabilitacie ) Ph.D. thesis TU Košice 1994

[6] HOLÝ, S. - VOLF, J.: Pressure Distribution Measurement Proc. of the 10th Danubia-Adria Sympos. on Exp. Methods in Mechanics Cz. Society for Mechanics, Sept 1993, pp. 105-105

This research has been conducted at the Department of Electrotechnical Eng. and at the Dept. of Elasticity and Strengh of Materials as part of the research project "Noninvasive Diagnostics of Pressure Distribution on Surface of Sole" and has been supported by the grant of Ministry of Education No 1170 (11-21009).

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MECHANICAL PROPERTIES OF SELECTED

BIOLOGICAL STRUCTURES

S. Holý, J. Kovanda*, J. Stingl**

CTU, Fac. of Mechanical Eng., Dept. of Elasticity к Strength of Materials Technická 4, 166 07 Praha 6

*CTU, Fac. of Mechanical Eng., Dept. of Automobiles, ICE & Rail Vehicles Technická 4, 166 07 Praha G

**Charles University, Anatomical Institute of the 3rd Medical Faculty Ruská 97, 100 00 Praha 10

Key words: biomechanics, injury, ankle, crash

New restrain systems in vehicles increase the importance of extremities protection. The article presents principal ways of research in the field of lower extremities injury, gives some results of stiffness measurement and mathematical modelling principles. This study is determined to present one approach of biomechanical study aimed especially to the injury analysis. It is limited to the ankle joint (AJ) structures without taking kinematics and dynamics of the whole human body or leg and their subsystems into consideration.

During last period following activities have been done with this respect:

1) definition of the substituing anatomical model of AJ, 2) determination of the stiffness of selected ligaments of A J, 3) construction of the mathematical model of A J for the simulation of kinematics of normal

movements of A J.

The methodology consists of following steps:

1) a) anatomical definition of simplified AJ model, b) comparison of the mechanical stiffness of the embalmed and unfixed ligaments and

tendons, c) the probably most important ligaments will be used in the study, i.e. anterior fibu-

lotalar ligament, calcaneofibular ligament, medial collateral ligament, and tibiofibular syndesmosis,

2) a) to create the metodological rules for determination of measurements of the joint ligaments stiffness,

b) to find the statistically important static stiffness of the above mentioned ligaments on embalmed and unfixed cadaverous material,

3) a) mathematical construction of kinametic model of AJ,

b) mathematical modelling of the conditions for the appearence of AJ injuries,

The study required to answer some basic questions in the very beginning stage of injury analysis development:

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1) the difcrcnces between embalmed and unfixed specimens material properties have to be determined, so as the statistic characteristics distribution changes of material,

2) the intial conditions have to be defined. It includes leg positions, i.e. the right leg on the brake pedal and the left leg on the floor (automatic transmision) or on the clutch (manually shifted gearbox) and relevant ankle join initial angles and muscle forces. The real occupant position immediate!ly before crash lias to be defined so as the geometry limits (95% male, 5% female),

3) the definition of movement restrains given by dashboard geometry and airbags inflation process,

4) the definition of injury process as dynamic or kinetostatic one. The injury could appear as a consequence of vehicle floor deformation and leg position is determined by surrounding structures deformation or in the consequence of dummy motion and its acting dynamic forces,

5) the used mathematical calculus and computer program of the whole crash simulation have to be specified. The FEM modelling and rigid body modelling require different input strategy.

This preliminary study presents the approach of A.l injury mechanism investigation. The continuation of this research methodology requires additional measurements, definition of widely accepted injury criteria, vehicle crash data acquisition with respect of ankle injury and application of computer simulation program of big complexity (M ADYMO, PAM-CRASH). Then partial results mentioned above could be applied to understand ankle joint injury mechanism.

References: [1] STINGL, J. - ALTSCIIUL, J. - GRUBER, V. - KOŠŤÁL, J.: To the diagnosis of

injuries of the external collateral ligament of the ankle joint Pilsen Med. Report 43: 37-42, 1976

[2] STINGL, J.: Contribution to the investigation of the vascular supply of the Achilles tendon Acta Cliir. orthop. Traum. czoch. 48: 163-168, 1981

[3] KOVANDA, J. - STINGL. J.: Critical tension by injury Report IRCOBI Internal Conference, Berlin 1991

[4] STINGL, J. - KOVANDA, J.: Measurement of Rcsistcncc of Internal Organs to Tension during Barrier Test (in Czech) Motor Veh. Research Inst. Rcf. 542/3/S9, Praha 1989

[5] HOLÝ, S. - STINGL, J. - KOVANDA, J.: Problematics of the mechanical properties determination of biological structures Proc. of the 11th Danubia-Adria Symp. on Experimental Methods in Solid Mechanics, Baden/Vienna 1994, pp. 45-46

This research has been conducted at the Department of Elasticity and Straight of Materials and at the Anatomical Institute of the 3rd Medical Faculty.

686


OPTIMIZATION OF PROSTHESIS OF CROSS LIGAMENTS OF A KNEE JOINT

V. Stejskal, M. Valášek, Z. Placková, M. Kasahara*

CTU, Fac. of Mechanical Eng., Dept. of Mechanics Karlovo nám. 13, 121 35 Praha 2

*Tokyo Institute of Technilogy, Mechanical Engineering Tokyo, Japan

Key words: kneee joint, ligament, mobility, model, higher kinematic pair

Injuries of the ligaments of a knee joint are very frequent due to sport activities and traffic accidents. They are treated by a prosthesis surgically. The problem is an optimal choice of the ligament length and the position of its fixation to meet the motion requirments of the knee joint. Incorrect choice of length and the position of fixation leads to limited function of a knee joint and to its enormous wear. The common practice now is to adjust the ligament length empirically in the course of operation.

The aim of research done under present grant is to develop a method and a computer program for specifying the correct ligaments length and the correct point of fixation on the surface of femur and tibia.

The problem is solved as an kinematic one. The final solution is approaching in several steps. They are: planar model of contact, spatial model of contact, and computer program for surgeon to assist during the operation.

In the present time two steps are completed. We will describe them in detail.

Planar model. The planar model of a human knee joint was created under the following assumptions: relative motion of femur and tibia is a planar motion, the way of constraint due to all four ligaments (two cross ligaments and two side ligaments) can be substituted by a link of constant length connected to he femur and tibia by rcvolute joints, and the surfaces of femur and tibia heads can be modeled as a planar curves the shapes of which are known.

Under the assumption just mentioned the knee joint can be modelled as planar higher kinematic pair with one binary link carrying a revolute joints on its both ends. From the structural mobility point of view it means that the assembly has one degree of freedom and kinematic solution is possible.

Method of solution. It is supposed that input data of a knee joint bones surfaces are available from computer tomography. The computer representation of the knee joint surfaces in our program is restored using cubic spline curves. In the course of motion three constraint conditions have to be satisfied:

• common point of two curves in contact

• common normal of two curves in contact point

• constant length of the binary link.

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Computer program was created for numerical solution of the position problem using MATLAB environment. The results of computation proved the capability of the simplified 2D model to check mobility and proper function of the knee joint.

Spatial model. The same approach was used in the case of more realistic 3D model. Spatial model of human knee joint was created under assumption that femur and tibia are in contact in two different points and the two bones are connected by two cross ligaments (ligamentum cruciatum) and two side ligaments (ligamentum collateralc). Tlie ligaments are again modeled by binary links carrying spherical joints at the each end. The contacts of the two surfaces is modelled by higher kinematic pairs. To meet one DOF mobility it is necessary to use only one side ligament. The same constraint conditions as in 2D model were used.

As much as 16 variables we have in this CÍISC. They are: S parameters describing points of surfaces contact, 2 parameters related lengths of normals in the points of contacts, and 6 parameters describing the position of one bone versus another.

Again the position problem leads to the solution of a system of nonlinear algebraic equations. These were solved using MATLAB program.

There was a problem of getting realistic data from surgeons. At present we do not overcome the problem of non-compatibility of data from computer tomograph and needs of our software. This was the reason that we simulated the shape of curves in 2D case and the shape of surfaces in 3D case with estimated data. Nevertheless the models proved their ability to check the proper kinematic function of the human knee joint.

During the next year the proposed task will he completed. Realistic data from surgeons will be taken into account and our computer program will be completed by optimization routine. We hope that the results of the project will help a surgeon to get better results in treating of knee joint injuries.

References: [1] SINELNIKOV, R. D.: Atlas anatomie člověka - díl l. Státní zdravotnické nakladatel

ství, Praha 1964. [2] FAUX, I. D. - PRATT, M. J.: Computational Geometry for Design and Manufacture.

Ruský překlad. Vyčislitčlnaja geometrija. Mir, Moskva 19S2. [3] PLACKOVÁ, Z.: Kinematický model lidského kolena. Diplomavá práce, FS ČVUT,

Katedra mechaniky, Praha 1994. [4] KASAHARA, M.: Optimization of prosthesis of cross ligaments of a knee joint. Re

search report. Dept. of. Mechanics, Fac. of Median. Eng., CTU Prague, Prague 1994.

This research has been conducted at the Department of Mechanics, Faculty of Mechanical Engineering, Czech Technical University in Prague as part of the rcseaivh project "Optimization of prosthesis of cross ligaments of a knee joint" and has been supported by CTU grant No. 28118.

688


HEMODYNAMIC RESEARCH BY ELECTRICAL BIOIMPEDANCE (EBI)

METHODS I. Uhlir, B. Sramek***, J. Tichy**,

S. Trojan*, M. Hojerova**, J. Bendl*, A. Parizek**, M. Preisler**, M. Uhlířova**

CTU, Fac. of Mechanical Eng., Technická 4, ICG 07 Praha 6

*First Medical Faculty of Charles University, Albcrtov 5, 120 00 Praha 6

**Institut for Medical Prevention and Care, Politických veznu 9, 110 00 Praha 1

***Cardiodynamics International Corporation, 19211 Edgehill Dr., Irvine CA92715, USA

Key words: hemodynamics, hepatorheography, pregnancy, teeth attachment

Medical Part: 1) Thoracic Electrical Bioimpcdancc (TEBI): Sramek's TEBI method, as incorporated

in BoMed CDDP System, was utilized, especially for the assessment of hypertension and for noninvasive hemodynamic management of hypertensive patients. In comparison to the conventional management of hypertension, the hemodynamic goal-oriented threrapy produced results which represent a 250-300cfficacy.

In 1994, the members of the Grant Team had a total of 13 publications, providing a detailed summary of used methodology and results. This is the part of the Grant currently covered in detail.

Expectations for 1995: Expanding the use of this approach into hemodynamic assessment under physical load conditions and adding pulse oximetry to assess oxygen Delivery.

2) Hepatorhcography: EBI curves were obtained from the hepatic region using BoMed's NCCOM3-R7. One sensing electrode was placed at the midclavian line of lower hepatic region, the other at the midscapular line of ThlO. Change in electrode placement produced a different set of curves. Expected detection of changes in parenchymatozoic perfusion could not be produced by mechanical change in electrode placement. To accomplish this task, electronic switching of an array of sensing electrodes by a computer with a simultaneous detection will have to be investigated. A quantitative and qualitative shift of EBI curves with a fixed placement of sensing electrodes as a result of pharmacologic intervention will require the same approach.

Significant results in this area are expected in 1995 with the availability of a two-dimensional rheograph inter- faced with a Personal Computer (PC).

3) Hemodynamic Assessmnet in Pregnancy: Noninvasive hemodynamic assessment of gravidas has been performed within the last year at the II. OBGYN Clinic of the 1st LF UK by BoMcd CDDP System. A total of 117 measure- menls on 21 healthy gravidas was obtained in 2-4 week increments during pregnancy. The data set is yet too small to produce statistically significant conclusions, however, it is already clear that, as the result of

689


pregnancy, there is a 30-55stroke index, a 20-30time, the ejection fraction remains unchanged and the mean arterial pressure increases only by 0-10

The plans for 1955 include continuation of data collection and addition of pulse oximetry.

4) Rheography of the Gum and Teeth Attachment: This area of EBI investigation was hampered by personal problems and delayed by a the necessity development of a special and universal electronic apparatus. BoMed NCCOM3-R7 cannot be used for this application. A special sensor was designed and its prototype tested. The team of researchers is ready to continue with the work started 20 years ago. At this time, there have hot yet been any results in this early stage of this noncon- ventional stomatologic research, which is the most techno- logically-demanding part of the Grant.

Expectations and plans for 1995: Improvement of the design of EBI sensor array and its interfacing with EBI multi- plexor and PC.

References: [1] SRAMEK, В.: New Method for Diagnosis and Management of Hypertension Mexican

Congress of Cardiology. 12/1994, Veracruz, Mexico [2] SRAMEK, В.: Systemic Hemodynamics: Review and New Findings 2nd lnt'1 Conf. on

Hemodynamics. 3/1994, Vechta, Germany [3] TICHY, J. - ČERVENKA, V. - HOJEROVA, M.: System sledováni hemodynamickych

dat a leeba arterialni hypertenze, cast I a H Vnitrni iekarstvi, in print [4] TICHY, J. - HOJEROVA, M. - UHLIR, 1.: Juvenilni hypertenze vc slari 1. zajazd

slovenskej kardiologickej spolocnosti s medzinarodnou ucastou. 9/1994, Sliac, Slovakia (Cor at Vasa)

[5] TICHY, J. - UHLIR, I. - HOJEROVA, M.: improved Outcome of Hypertensive Patients Using Sramek's Hemodynamic Management Chart 2nd lnt'1 Conf. on Hemodynamics. 3/1994, Vechta, Germany

[6] SRAMEK, B. - TICHY, J. - ČERVENKA, V. - HOJEROVA, M.: Improved Outcome of Antihypertensive Therapy by Utilizing Hemodynamic Data Processing System Submitted for publication

This research has been conducted at the Dep. of Electrotechnical Eng. of CTU as part of the research project "Research of The Hemodynamics by using of The Eleclroimpedances Methods" and has been supported by Grant Agency of Czech Rep. grant No. 106/94/1554-

690


RESEARCH OF THE HEMODYNAMICS BY USING OF THE ELECTRO-

IMPEDANCES METHODS I. Uhlir, B. Sramek**, J. Valenta, V. Pražma,

S. Papežova, J. Chyšky, P. Charvát*

CTU, Fac. of Mechanical Eug., Technická 4, 166 07 Praha 6

*First Medical Faculty of Charles University, Institut of Physiology Albertov 5, 120 00 Praha 2

**Cardioclynamic International Corporation, 19211 Edgchill Dr., Irvine CA92715, USA

Key words: clcctroimpcdancc, hemodynamics, measurement current, frequency, phase demodulator

Technical Part: Development of Apparatus for EBI Measurement: 1) Assessment of the EBI measurement parameters of the existing system (BoMed

NCCOM3-R7): Measurement Current: 2.5 mA RMS Measurement Frequency: 70 kHz EBI amplifier:

Wide-band Detection: Peak detector Basic measurements with the existing system performed at the: a) Thorax b) Hepatic region c) Gum 2) Definition and selection of measurement parameters for the new system: Measurement Current: 1 mA RMS Measurement Frequency: 100 kHz EBI amplifier:

Tuned, Bandwidth 10 kHz / 6dB Detection: Phase demodulation The reasons for the changes were: (a) The intended multi- electrode, multiplexed array

required the increase in measurement current frequency, (b) magnitude decrease of the measurement current was driven by potential pressures from regulatory agencies for increased safety, (c) tuned amplifier in conjunction with phase demodulation has a potential for better signal-to-noise ratio.

3) A prototype of an universal test equipment was designed with the above-defined parameters and built with ranges of 1-10-100-1000 mV at the analog output of 1 V.

'1) This prototype was used for EBI measurements with the following results: A) The detected and processed thoracic signal was identical with that of BoMed

NCCOM3-R7. B) The EBI signal detected in the hepatic region was similar to the signals described

in the literature. Since the amplitude of the detected signal was strongly dependent both on the electrode placement and the constitu- tion of the patient, and due to a need to detect only the relative changes in hepatic perfusion, a new EBI approach, using a surface array of multiplexed electrodes, was adopted.

C) The gum measurements were performed with a specially- molded fixture accomodating and matching the upper frontal teeth 5-5. The gum-contacting electrodes, 0.5 mm in diameter, were made out of a non-corrosive material. We expect that this type of electrodes

691


can also be inserted between the gingiva and the tooth. An EBI signal of a small magnitude was detected; however, we cannot provide a physiologic interpretation of this signal at this time. In addition, its magnitude was placement-depcn- dent. Since the situation is similar to the hepatic measure- mcnts, we expect better results with a two-dimensional array of multiplexed surface electrodes, or, at least, with a linear electrode array.

The technical development in the near future intends to: 1) complete the development of a universal EBI system, which will accomodate a surface

array of multiplexed electrodes, and transfer the data to a PC, 2) continue in the development of the gum array, 3) expand all flow and perfusion measurements by adding the saturation level of arterial

oxygen in blood by pulse oximetry, 4) expand the hemodynamic measurement by CDDP System by measurement under

load conditions (ergometer). The corresponding equipment to points 3) and 4) has been purchased in 1994 during

the equipment acquisition phase.

References:

[1] SRAMEK, В.: Hemodynamic Management Chart for Supine, Resting Adults 2nd Int'l Conf. on Hemod. 3/1994, Vechta, Germany

[2] SRAMEK, В.: Noninvasive Hernodynamic Monitoring and Management: New Concepts Univ. of California San Diego, Dpt. of Family and Preventive Medical Clinic Epidemiology Conference. 7/1994, UCSD, La Jolla, California, USA

[3] SRAMEK, В.: Rapid Treatment of Hypertension through Identification of Its Hemodynamic Causes Inst, of Experim. and Clin. Med. Symposium, 7/1994, Univ. of PJ Safarik, Kosice, Slovakia

[4] SRAMEK, В.: New Concepts in Noninvasive Hemodynamic Management 5th Int'l Congress: Biomechanics of Man. 9/1994, Benešov, Czech Republic

[5] TICHY, J. - UHLIR, I. - HOJEROVA, M.: Hrudni elektrická bioimpedance Časopis lekaru ceskych, in print

[6] TICHY, J. - UHLIR, I. - HOJEROVA, M.: Hrudni elektrická bioimpedance, tepový utlum a tepová prače Prakticky lekar, in print

[7] UHLIR, I. - CHYŠKY, J. - TICHY, J. - UHLÍŘOVA,' M.: Spolupráce lekaru a techniku 17. světový kongres pro védy a uměni. Praha 1994

This reseai-ch has been conducted at the Dep. of Electrolechnical Eng. of CTU as part of the research project "Research of The Hemodynamics by Using of The Electroimpedances Methods" and has been supported by Grant Agency of Czech Rep. grant No. 106/94/1554-

692


ADAPTATION OF THE CORTICAL FEMORAL BONE DUE TO THE

EXTERNAL LOAD M. Petrtýl, J. Heřt*, P. Fiala*,

R. Vondrová, В. Czesaná

Faculty of Civil Engineering, Department of Structural Mechanics and Biomechanic Czech Technical University, Prague, Czech Republic

*Medical Faculty, Charles University, Department of Anatomy Plzeň, Czech Republic

Key words: osteons, bone structure, bone loading, functional adaptation, artificial hip implants

A new macroscopic method based on the filling of vascular canals of the undecalcified, polished bone with India-ink enabled us to study the spatial architecture of the haversian bone in the entire diaphysis. The osteons in all long bones in man arc grouped in two helical antirotary systems of opposite oblique directions, situated in the contralateral walls of the diaphysis. Several arguments are presented in favour of the hypothesis that this special architecture belongs to functional adaptations and that it depends on the orientation of the first, dominant principal stress in every point of the diaphysis.

The hypothesis was tested in the femur of man. The osteon direction was compared with the direction of the first principal stresses, determined analytically in a model of the diaphysis, represented by a cylindrical tube bar, subjected to a combination of bending, torsion and compressions. Moreover, the osteon organization was studied in femurs of atypical forms.

Under combined loading of the tubě with the bending moment in the frontal plane to the medial side and with the torque moment in the sense of external rotation, the direction of the first principal stresses corresponds with the direction of osteons in the diaphysis of the femur. In both cases, the first principal stresses, as well as the osteons, are oriented in the opposite oblique direction in contralateral walls of the medial and lateral walls of the model and of the bone. Between the two oblique fields a sharp boundary with an atypical organization of the principal stresses and osteons exists.

The hypothesis is supported by the atypical osteon organization in three femurs, with all probability unloaded in vivo. The dominant orientation of osteons is longitudinal. In two other femurs of atypical form, strikingly convex in the anterior direction, the typical osteon pattern is rotated by 90o against the normal situation.

Results of our analyses and observations testify the correctness of the hypothesis that a causal relation exists between the loading modes of the bone and the dominant direction of osteons. The organization of the haversian bone represents a typical example of functional adaptation.

The results of our analyses are of great importance for the development of new hip prostheses.

693


References:

(1] PETUTÝL, M.i HaicltviUu of [he Compact Femoral Hone lo the lixlernal hand, In: Proc, XlVth Coiujrcs ISli, Paris pp. 1028-192»,1993

This research has been conducted at (hi Department of Structural Mechanics at the Faculty of Civil engineering and «< the Institute of Anatomy of Charles University in Plzcu and tins been supported by Faculty of Civil Engineering grant No.ltJSIfl

694


APPLICATION OF SEMI-RIGID CARBON-FIBRE-REINFORCED PLATES

FOR FIXATION OF HUMAN FRACTURES S. Konvičková, M. Sochor

CTU, Fac. of Mechanical Eng., Dept. of Elasticity Si Strength of Materials Technická 4, 166 07 Praha 6

Key words: inner osteosynthesis, plate, composite materials

There are occasional fractures of long bones which can only be treated properly by means of the internal fixation. To achieve the maximum benefit from fixation, unrestricted movement of the neighbouring joints should be allowed, with freedom from external splintage. Such a fixation must be very strong, and if steel plates arc used the thickness necessary for this strength imposes rigidity of the structure. Increasing experience with rigid fixation has brought to light two important complications, both of which stem from the fact that the virtual elimination of movement at a fracture totally inhibits the formation of external callus, and union lias to take place directly between the bone ends: the so-called primary or remodelling bony union. Clinical experience has shown that in the human subject it is an extremely slow process and current recommendations for the tibia suggest that steel plates cannot be removed safely for at least 18 months after the injury. This leads to problems of implant failure. More common and equally serious is the ostcoponia which develops beneath very strong steel plates as a result of protection against stress which they confer (the weakening of the bones leads to a substantial rate of rcfractures). It has been pointed out by some authors that the ideal fixation for a fracture is one which offers security to the extent that normal use of the Jimbs is possible, and flexibility sufficient to allow movement at the fracture site, and hence promote rapid bony unionby the development of external bridging callus — in other words, semi-rigid fixation.

These demands are fulfilcd, to a sufficient extent, by carbon-fibre composite plates. The semi-rigid plates have been constructed, by our research team, from cpoxy resin reinforced with carbon fibres (C/E-composite). Alongside C/C-composite, comprised of carbon fibres in carbon matrix (obtained from the carbonation of a phenol-formaldehyde resin at relatively high heating rates 22 and 35 K/hr) has been considered and its characteristics studied. First approaches to the computation of the stiffness and strength of the designed composite plates have been undertaken using the Cosmos program. In the initial stage, the FEM model describing the plate shape, taking into account two patterns of the screw holes, has been carried out. Simultaneously, a substantional effort has been made in the developing of a new type of epoxy resin into which a special filling material has been added in order to obtain a material showing the gradually decreasing stiffness with the time of exposure in the body. As to the plate composition, new ways of the orientation of uniaxial pre-pregs have been examined. The main effort has been allocated to finding out such a composition of the plate, with the least possible number of free fibre ends, that would simultaneously enable adjusting the required degree of plate rigidity.

695


References: [1] SOCHOR, M. - VALENTA, P.: Application of Composite Plates. In Czech, Research

report No, 211-88-6 (.1013), CTU-PMEin Prague, 198-1, 8-1 pp, [2] VALENTA, P. - SOCHOR, M. ct al.: Application of C/E Composite Plates to Pigs.

In Czech, Research report No, 211-90-9 for research programme of "Biomechanics of Man", CTU-FME in Prague, 1990, 37 pp.

[3] VALENTA, P. - SOCHOR, M. - К VET, V.: Application of C/E Composite plates to Pigs. In Czech, In: Proceedings of the international conference "BIOMECHANICS OP MAN '90", ÚTAM-CSAV (CSAS), Liblicc, 1990, p. 193 - 195.

[4] KVET, V. - VALENTA, F. - SOCHOR, M. ct al.: The Application of Composite Plates in Orthopaedy (poster)., In: 1st World Congress of Biomechanics, University of California, San Diego СЛ, USA, 1990

[5] KVET, V. - KRENA, .). - SOCHOR, M. - TOUZIN, G.: The Research of Synergic Effect in Advanced Composite Plates Applied in Orthopaedics In: Proceedings of MPC '91, CSAV-ÚTAM (CSAS), Praha, 1991, p. 355 - 357.

[6] VALENTA, P. - SOCHOR, M.: Biomechanics of Inner Osteosynthesis, In: Proceedings of Workshop '93, ČVUT (CTU), Praha, 1993, p. 21 - 22.

This research has been conducted al the Department of elasticity & strength of materials as part of the research project "The Composite Materials and the Surface Modification of Bioimplantants to be used in Osteosynthesis" and has been supported by Grant Agency of the Czech Republic Grant No. 106/9/,/П01.

696


THE DEVELOPMENT OF GRADIENT COATINGS SiNx BY IBAD METHOD

FOR IMPROVING PROPERTIES OF METAL BIOIMPLANTS

S. Konvičková, F. Černý*, R. Valenta*, I. Kvasnička**, P. Zuna***, J. Michalec, V. Hnatowicz, P. Svoboda

OTU, Fftc. of Mechanical Eng., Dept. of Strength of Materials Technická <t, 1G6 07 Praha 6

*CTU, Pne. of Mechanical Eng,, Dept, of Physics Technická 4, 166 07 Praha 6

**CTU, Рас. of Mechanical Eng., Dept. of Machining & Process Planning Technická 4, 166 07 Praha 6

***CTU, Рас, of Mechanical Eng,, Dept. of Materials Science Karlovo nam. 13, 121 35 Praha 2

Key words: bioimplants, SiNx coating, IBAD method, concentration profile

Metal bioimplants should have satisfactory tribological and corrosive properties. Released metal may be transported through body fluids to remote tissues (liver, spleen, brain, etc.), inducing cytotoxic and allergic effects. Patients receiving metal implants (such as total hip joint replacements, osteosynthesic plates and nails or dental implants) show, within a short time, an important increase in the metal content of their body fluids (up to two orders of magnitude higher than normal levels). To prevent the wear and corrosion a hard coating for the metal bioimplants has been suggested. Some of these, e. g. titanium nitride coating, arc already applied, Another suitable candidate for this application is silicon nitride [1], which also has many other potential applications.

We have chosen the preparation of gradient coating SiNx. Its properties (including mechanical ones) can be changed through its cross section in the dependence on the composition (concentration of nitrogen). We suggested parameters of the preparation process in such a way that resulting model gradient coating would have a decrease in concentration in the direction of the substrating divided into two steps in order to create an area with aproximatcly constant concentration inside of the coating. The aim of the presented stage of development of the coating was above all to gain control of its preparation and measuring of the concentration of nitrogen through a cross section of the coating (depending on the depth, i. e. concentration profile).

The SiNx coatings were prepared by the IBAD (Ion Beam Assisted Deposition) method. In this method, the coating is created by simultaneous deposition and ion implantation. By this method, it is possible to construct concentration profiles of the various shapes by variyng of the processing parameters.

The ion implantcr TECVAC 221 in connection with equipment for evaporation by electron beam TEC - 5 for prepartion of coatings. The energy of the accelerated nitrogen ions is 90 keV.

697

WORKSHOP 95 BIOMEIMCALENGINEERlNCi

Tlie works carried out in the area of prcpn rating SiNr coating by the 113 A ID method (e, g, [2, 3]) proved that prepared SiNx coalings are amorphous independently of choice of substrate. That is why the substrate was chosen to satisfy the intended measurrment. For our planned measurement by methods of transmission, infrared spectroscopy and RI3S (Rutherford Back Scattering), the silicon substrates were optimal.

мпн|*'»1 WAVE NUMBER | » V l Fig. 1 Fig- 2

The resulting constructed concentration profile, which was created by superposition of partial concentration profiles, was measured by the RBS method by alfa particles with initial energy 1,3 McV. Measured values are shown in Fig. 1. Fig. 1 also shows partial concentration profiles and the resulting, summed concentration profile according to our mathematical model. The discrepancy in the values of concentration near the surface is explained by another mathematical model, which considers radiation stimulated diffusion in the critical surface area, in which the maximal energetic losses of implanted ions takes place,

Fig. 2 shows the infrared absorption spectrum of the SiNx coating. The marked broad absorption peaks at wave number aproximately 8,2 . 10'' m_1 corresponds with the stretching vibration of created Si - N bonds. The broad character of this peak and the absence of peaks, which arc for both crystallic modifications of silicon nitride are typical for amorplious state of IBAD SiNx coatings.

The other properties of IBAD SiNx coatings, including tribological and corrosive ones, will be investigated in the next stage of research.

References: [i] SELLA, С - MARTIN, J. С - LECOEUR, J. et al.: Mater. Sci. Eng. A 139 (1991)

49 [2] GRABOWSKI, K. S. - KAIIN, A. D. - DONOVAN, E. P. et al.: Nucl. Instr. and

Meth. В 39 (1989) 190 [3] NATISHAN, P. M. - MC CAFFERTY, E. - DONOVAN, E. P. et al.: Surf. Coat.

Tcchnol. 51 (1992) 30

This research has been conducted at the quoted workplaces of the autors of this work as a part of the research project "The Composite Materials and Surface Modification of Bioimplants to be used in Osteosurgery" and has been supported by the Grant Agency of the Czech Republic, No. 106/9^/1701

698


THE RESEARCH ON CARDIOVASCULAR MECHANICS

J. Michalec, J. Valenta, S, Konvičková, J. Řezníček

CTU, Fnc. of Mechanical Eng., Dcpt. of Elasticity к Strength of Materials Technická 4, 166 07 Praha 6

Key words: cardiovascular mechanics, soft tissue, nothingthe aging of tissue, strain energy, biological tissue

During biosystem growth, maturity and aging, both soft and hard tissues undergo cyclic mechanical loading, being thus occasionally subjected to large strains and rotations.

The redistribution of the mass and force (lows in the tissue causes changes of the tissue structure. This occurs, for example, during gradual development of residual stress in the arteries and myocardium, in the remodelling trabecular orientations in bone and in many other instances.In the course of biological time, both desirable and undesirable growth and decomposition of the living tissue occur as the consequence of mechanical and biochemical processes.

In accordance with this, subjected to study were the strain energy function and the constitutive equation of living tissue (based on hyperelasticity theory), using rotationless strain. The proposed eigenvalue decomposition of the rotationless strain tensor and the hyperelasticity strain energy function were formulated as depending on biological time of the tissue. The corresponding constitutive equation of tissue depending on the biological time was determined, The coefficient of tissue aging was also defined. This being a significant diagnostic parameter for assessing the structural changes of tissue, due to both its aging and the pathological processes.

Numerical results reveal that the coefficient of aging progressively increases in the hardening tissues (coronary artery, vena cava inferior) whereas in the softening tissues it shows a relatively slow increase in dependence on tissue aging. The results were published in Japan (Bio-Medical Materials and Engineering, No 4, 1994).

A model of the human arterial bed was also proposed, consisting of 128 branches along with the dimensions of the ventricles, the left atrium and of aortic base, obtained by the examination of healthy childern aged between birth and 18 and in accordance with body weight.

Studies undertaken so far have shown some problems concerned with the non-linear response of the large lumen arteries influenced with residual stress and undergoing large strain, together with the dynamic response of the arterial wall in vivo and some mechanical factors that contribute to the growth and rupture of bulged aneurysms.

The analysis of residual stress requires knowledge of how changes occur, through age, in geometrical parameters, which define the zero-stress state and the rheological properties of the wall.

Based on the idea of hyperplasia of the artery wall tissue and of the myocardium, a general continuum formulation for finite volumetric growth in the soft tissue has been used. These results will be published in the book "Biomechanics of the Cardiovascular System", Foundation for Biomechanics of Man, Prague - Irvine USA, 1995.

699


References: [1] VALENTA, J. et al.: Biomechanics. Elsevier, Amsterdam - New York - Tokyo, 1993. [2] VALENTA, J. - KLIMEŠ, F. - KITTNAR, 0.: Biomcchanika srdečně cévního systému.

ČVUT (CTU), Praha, 1993. [3] GLASS, L. - HUNTER, P. - McCULLOCII, 0.: Theory of Henri. Springer - Verlag,

New York, 1991.

TViis research has been conducted al the Department of elasticity & strength of materials as part of the research project "Education of 'Cardiovascular mechanics' in Biomedical Engineering" and has been supported by Ministry of Education Grant No. 1177/1994-

700


ELECTROMEGNETIC EXPOSURE OF MOBILE-TELEPHONE USERS

J. Vokurka, J. Vrba, Z. Škvor, R. Dlouhý

CTU, Fac. of Electrical Eng., Dcpt. of Electromagnetic Field Technická 2, 166 27 Praha 6

Key words: mobile telephone, exposure of human head, phantom of a head

The aim of the grant is to study the bio-elcctromagnctic effects of mobile phones on the users body, particularly the head. The present state of this problem, in the existing literature involves the numerical computations of field distribution inside the head. The complexity of the mathematical models goes from a simple sphere [1] to detailed structure from tomography cuts [2],[3]. Less arc presented experimental measurements. The activity of most specialists from throughout Europe is concentrated in the project COST 244 "Biomedical Effects of EM Field" where one working group is interested in problems of mobile phones and the human body.

Our activity in the grant is as follows: a) Numerical computations of EM field distribution. We chose for it the MMP method

(Multiple MultiPoles) whose attraction is its discretization on the boundary of regions only. Wc have a program which enables us to prepare input data of the general form of 3D boundary, to calculate the field distribution and then to visualize it by different means. We used this program to calculate the field in simple models of the head (spherical, cubic and round) generated by a half-wave dipóle from different distances. We found some kind of resonance of the head in the 900 MHz band and a matching influence of the cranium (higher power was absorbed).

b) We realized experimental phantoms of the head (spherical and cubic ones) to measure the field of different telephone sets. They allow us to compare different numerical methods of calculation too, as these forms of regions have analytical solutions. To the set belongs measurement probe which should be small (not to disturb the measured field) and sufficiently sensitive (to measure the attenuated field of real telephones). We had to choose a convenient diode, optimize its equivalent circuit, and then test its output. The probe is connected to an arm steered by a computer. The output data enable us to get the field distribution transmitted into the phantom of the head.

c) The measurement of power radited by the telephone in the presence of a human head was next. First we measured the radiatin pattern of the phone situated in free space. Due to the helix antenna of the phone, both components of the field (horizontal and vertical) were measured. Then the radiation patterns were measured in the presence of a human head. It was found that aproximately 70% of the power was absorbed. Even though it is a large part of the power, not too much thermal effect can be expected (particularly in case of cordless phone which radiates low power). Nevertheless nonthermal effects can appear. Numerical calculations of the full model of the head show that most is absorbed in region of the middle ear. As we can not easily do direct measurements inside the ear cavity some indirect observations had to be done. The ORL experts expect some changes in the treshold of audibility. The earphone will be used in the set of audiometer. We prepare the

701


first measurements with Prof. Bclka from the ORL clinic in Prague. He seggcsted that we also prove other functions of the car, such as the emisivity of the car by the incidence of acoustical puis, which can be influenced too.

In conclusion wc can say that in the year 1994 we finished the introductory acquaintance on the individual parts of these problems and we are now in the position to start extensive numerical computations of detailed model of the human head (structural data of the head are place to our disposal), to search for nonthermal ciTects of EM field in the middle car and to do measurements on salty-water models of the human head.

References: [1] TOFTGARD, J. - HORNLETII, S. N.: Effects on Portable Antennas of the Presence

of a Person, IEEE Trans. ЛР 41,No.6, 1993, pp. 739 - 746. [2] KOULOULIAS, V. - UZUNOGLU, N. - KONSTANTINOU, P.: Non-ionising Radia

tion Generated by Hand-held Mobile Radios, BEMS, 15th Annual Meeting, Rome, Italy, 1993.

[3] EXCELL, P. S. - JACKSON, N. N. - OLLEY, P.: Studies of RF Absorption in the Human Head, BEMS, 16th Annual Meeting, Copenhagen, Denmark, 1994.

This research has been conducted at the Department of Electromagnetic Field as part of the research projed "Electromagnetic Exposure of Mobile Telephones Users" and has been supported by CTU (TU) grant No. 8199.

702


APPLICATORS FOR PHOTODYNAMIC THERAPY

K. Novotný, J. Vrba

CTU, Fac. of Electrical Eng., Dept. of Electromagnetic Field Technická 2, 166 27 Praha б

Key words: photodynamic therapy, radiation pattern

Introduction. Fibre applicators for photodynamic therapy, in connection with photosensitive chemical preparations, arc very effective instruments for highly selective therapeutic functions on cell entities of bane cell tissue. Laser, as a source of the intensive optical radiation, is used in photodynamic therapy. The specially adapted optical fiber, with a different geometry at the output-end, is used for optical radiation supplying selected areas of the treated tissue. One of the key problems of phototherapy is the need for an accurate dosing of optical radiation, and its space distribution, which must correspond with the geometry of the tumour centre.

Technical parameters of the optical applicators. The Optical applicators for the photodynamic therapy, are special fiber guides with a core diameter of a few hundreds microns. Plastic cladding of the fiber is often used. As a rule, the numerical aperture of fiber is greater than 0,4. Therefore, a simple input of optical energy to the applicators is possible. The radiation pattern of the applicators is determined by the fibre-end geometry. The common fibre output end geometry for the application of the optical radiation in to the tissue, is depicted in the following picture.

Fiber \ t / Fiber \ | | \ / Fiber ^\A^/

/ | ^ / I t | \ ^ Fig. 1: Fiber-end geometry.

The measuring equipment. For the easy measurement of the radiation patterns of fiber optical applicators, this measuring equipment was proposed. It consists of a semiconductor laser diode Toshiba TOLD-9200S, with 3 mW output power on 670/im. The pigtailed laser diode with connector can easily be connected with the fiber applicators. The PIN photodiode Honeywell HFD 3002 with a fibre probe for optical radiation detection is used. The probe is made with an input aperture of optical fiber with core/cladding 50/125/ťm diameter. The probe is fixed on the turning arm with the centre rotation in the neighboring output end of the applicator. The arm turns in the range from -т/2 to +я/2 and is driven by stepper motor. The movement of the stepper motor and photodetector indication, is controlled by a computer through special software. The proposed method of

703


optical energy scanning by means of the fibre probe is energetically noneffective, but is used for the possibility of measuring radiation-patterns in liquid. Liquid allows a quantity of tissue representation. To remove problems with false signals, which originates in the clay illumination of the probe, the source of radiation is modulated by a 1 kHz signal.

Results of measurements As an cxamplc,wc refer to the radiation pattern of a cylindrical applicator. The fused silica core diameter is 600/zm, cladding diameter 70/im, and the numerical aperture is 0.4. The end of the applicator is without cladding for a length of 1 cm. The Applicator is located in distilled water, the centre of rotation of the probe is in point S (see Fig. 2.). The distance of the probe from point S, is 3 cm. The radiation pattern (Fig. 3.) is standardized.

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Fig. 2: Measurement arrangement. Fig. 3: Radiation pattern.

Conclusion. The constructed equipment and created software, enable the effective automatical measurement of the radiation patterns of optical applicators. These are the basis for the proposition of applicators with required radiation patterns. Following research will be directed towards the study of medium influences on the radiation from applicators, and on the possibility of an automatic optimal choice of applicators, achieving the desirable optical power distribution in the tissue.

References:

[1] SCHRÓFEL, J. - NOVOTNÝ, К.: Optické vlnovody. SNTL/ALFA Praha 1986. [2] KAO, C. K.: Optical Fibre. Peter Pcrcgrinus Ltd.,London 1988.

This research has been conducted al the Department of Electromagnetic Field as part of the research project "Charakteristice measurements of the applicators for photodynamic therapy" and has been supported by CTl/ grant No. 8193.

704


SIMULATION OF COMPARTMENTAL MODELS OF NEURONS

D. Suta1'2

'CTU, Fac. of Electrical Eng., Dept. of Control Engineering Karlovo nám. 13, 121 35 Praha 2

2AS CR, Institute of Experimental Medicine, Laboratory of Auditory Neurophysiology Vídeňská 10S3, 142 20 Praha 4

Key words: neuron, compartmcntal model, simulation

Modeling of neuronal structures has become an important tool in neurosciences for the comprehension of processes in biological systems [4]. The importance of computer models increases with the development of new methods in ncurosciences, with the increasing computer efficiency and with new motivations coming from the branch of artificial intelligence. Many phenomena in real neurons and neuronal networks can be explained by the simulation of adequate models - one group of which constitutes compartmental modeling. Compartmcntal modeling is derived from the linear cable theory and its application is supported by many features of real neurons (e.g. the complex morphology or different intrinsic biophysical properties of individual neuron parts). A software tool created for simulation of realistic models of neurons and neuronal circuits on the PC is presented.

The neuron model is constructed from many connected isopotential compartments. The membrane potential V; of the i'-th compartment is given by the relation :

dVi 1 t r , , —jr = —Q \hu + hi + hi + JNi),

where d is the membrane capacitance, /д/,- is the membrane current, Ici is the current injected from neighbouring compartments, /s,- is the synaptic current and Im is the membrane noise.

Two types of compartments are distinguished by form of the membrane current IM,: passive and active. In passive compartments, the membrane current contains only the leakage current representing spontaneous return to the resting potential. Passive compartments are used mainly for the simulation of the dendritic tree. In addition to the leakage current the membrane current of an active compartment contains currents due to voltage-dependent ion channels [1] described by Hoclgkin-Huxley type equations [3]. The presence of ion channels ensures the membrane excitability and generation of action potentials. The program admits incorporation of intracellular ion pools which can enhance or attenuate the ion channel conductances (e.g. Ca2+ pools for control of Ca2+-activated channels). Somatic and axonal domains are constructed from active compartments.

Input events coming through chemical synapses to the г'-th compartment are expressed by the synaptic current Isi- Both synaptic types - excitatory and inhibitory - can be modeled. The time distribution of presynaptic spikes can be deterministic or stochastic with the nonstationary dead-time-modified Poisson distribution [2] that reliably approximates the sequence of presynaptic action potentials. The natural stochastic character of the neuronal activity is built into the model not only by randomly distributed synaptic events, but

705


also by an additional noise lm in the form of the Gaussian white noise current input [4]. Spontaneous fluctuations in the membrane potential trajectory evoked by this current noise bring model properties nearer to reality.

The model output is characterized by required characteristics such as displayed membrane potential trajectories of selected compartments or by the sequence of action potentials saved into an ASCII file. The combination of graphic and numerical outputs give a detailed view of modeled actions in the temporal and spatial context. Moreover, data can be used for further statistical analysis and for the creation of relevant histograms [2] - the form of simulated results is thus compatible with the standard presentation of experimental results.

The program was written in С programming language and implemented on a PC <186 computer. A simple integration method based upon the Euler schema with a constant step size was used for reason of simplicity; however, such a method docs not sacrifice reliability.

A complex software package for the development and simulation of compartmcntal models of neurons is being introduced. This simulator incorporates necessary tools for realistic modeling of processes in neurons and neuronal circuits and may be applied to research of such neurophysiological aspects as ionic basis of action potentials and neuronal excitability, current flow in dendritic trees, synaptic transmission, effect of membrane noise, properties of simple neuronal circuits etc.

Application of the described simulator is aimed towards the simulation of information transmission in the auditory pathway. However, the application is not restricted only to this structure and can be expanded to other neuronal structures. First results obtained by this software have been presented in [3]. In the further work the simulation software will be used for the modeling of information processes in single neurons and local neuronal circuits in the auditory midbrain.

References: [1] HILLE, В.: Ion Channels of Excitable Membranes. 2nd edition, Sinaucr Ass., Sunder

land, Ma, 1984. [2] ROTHMAN, J. S. - YOUNG, E. D. - MANIS, P. В.: Convergence of Auditory Nerve

Fibers Onto Bushy Cells in the Ventral Cochlear Nucleus: Implications of a Computational Model. J. Neurophysiol. 70: 2562-2583, 1993.

[3] SUTA, D.: Spontaneous Activity in Auditory Neurons: Application of a Stochastic Model. Theoretical and Clinical Aspects of Neurosciences. Proceedings of the 1st Conference of the Czech Neuroscience Society, p.98, Prague, 1994.

[4] TUCKWELL, II. C : introduction to theoretical neurobiology. Cambridge University Press, Cambridge, 19SS.

This research has been conducted in cooperation of Dept. of Control Bng. with Institute of Experimental Medicine and has been stipported in part by GA CR 309/9^/0735.

706


CLOSE RANGE PHOTOGRAMMETRY AND DIGITAL ELEVATION MODEL

IN SPECIAL PURPOSES K. Pavelka

CTU, Fac. of Civil Eng., Dcpt. of Mapping & Cartography Thákurova 7, 166 29 Praha 6

Key words: medicine, photogrammctry. digital elevation model

Within the Central European Iniciativě (CI3I) we have the possibility to use software products SCOP (digital elevation model) and ORIENT (photogrammctry). ORIENT is a universal program system intended to calculate and adjust a set of phologrammctric points to the reference system. The use of the system ORIENT is advantageous in a non-gcodetical field, too, for example in medicine or in architecture. For the purpose of technical backwarding in postcommunistic states in the field of analytical processing system ORIENT seems to be very valuable (in the Czech republic there are only 5 analytical plotters at present). Image processing from non-metric cameras and non-normal photogrammetnc cases is possible with system ORIENT; they were not used on analogical machines.

For photogrammetric testing, a small test object was selected, photographed, and geode-ticaly measured. The test object was a building in the photogrammetric test range of Technical University in the village of Srbsko near the city of Beroun. Photography had been taken with a metric camera UMK 10/1318 (Zeiss Jena) and a non-metric camera KIEV 6x6/80. In the case of the metric camera, a glass photograhic plate ORWO (9 DIN) was used; the non-metric camera, on the other hand, used black and white film FOMAPAN (21 DIN/100 ASA). About 40 control points were gcodccically measured on the object with accuracy of about S mm. Photography was measured on precise stcrcocomparator STE-COMETER (Zeiss Jena) with help of a new registration instrument CNT with an accuracy of 0,004 mm. In the photography from metric camera fidticials, control points and object points were measured (inner orientation was known), As there are no fiducial marks on the non-metric camera, four image corners are used as fiducial. The calibration had to be done for focusing 15m and infinity. The result after the final adjustment was an accuracy about 1,1/1,9 cm on the object points for the metric /non-metric camera.

For practical applications of this process, ORIENT is useful for medical advancement. For example, rehabilitation medicine needs knowledge about the condition of the backbone. The use of ORIENT has advantages in:

- using non-metric cameras (easy for transport) - great speed of measurement - low price of material - measurement is not dependent on the laboratory An object (a patient) is photographed in front of a wall or in a corner of a room from

2 or 3 positions from a distance of about 1,5m. We have 2 ground possibilities for the coordinate system:

707


- coordinate system (x,z) in front of wall - build a coordinate system with the help of the room coiner (for х,и plane we must

compute a rotation)

Control points arc needed for processing, which we can make on a white wall (points on the wall and spatial points on sticks — about 8 control points). Object points arc signalized by a slide projector with a grid on the slide (about 2000 points, are possible to use). The base used is about 40 cm, camera KIEV Cx6/S0 (non-metric), film black and white 100 ASA. Photography is measured on stercocomparator STECOMETER with registration on a floppy disc. Autocalibration is used for non-metric cameras (by running program). Adjusted coordinates of object points have accuracy of about 0.5mm, and that is good enough for documentation of the backbone condition. The semi-final result is, however, a set of spatial points (3D-coordinatcs).

The final result is the contour line plane for presenting with the haid of the digital elevatin model. Contour lines are generated with SCOP software (Figure l).This method of documentation will be tested in the hospital "Na Homolce" in Prague.

ORIENT 1: 300

Fig. 1: Contour lines

References: [1] WALDHEAUSL, P. - KAGER, H.: ORlENT-a universal photogrammetric adjustment

system product information, Institute of Photogrammetry and Remote Sensing, TU Vienna, 1990

[2] BALOGH, B. et al.: Fhotogrammetry of the muscles of facial expresion Acta Anatomica 1988, pp. 183-187

This research has been conducted at the Department of Mapping and Cartography, CTU Prague and has been supported by CTU grant No. 2087.

708


NEW MAGNETIC MATERIALS FOR MEASUREMENT TECHNOLOGY

P. Ripka, K. Draxler, P. Kašpar, J. Roztočil, R. Kasal

CTU, Fac. of Electrical Eng., Dcpt. of Measurements Technická 2, 1G6 27 Praha 6

Key words: magnetic materials, instrumentation, magnetic measurement

Amorphous and nanocrystallinc soft magnetic materials are serious candidates to replace traditional crystalline materials in magnetic circuits used for instrument transformers, power chokes, magnetic sensors, magnetic shields and other devices. The magnetic and electrical parameters of these materials allow us to decrease the core volumes, increase the operating frequency, decrease power losses, and increase precision. The specific mechanical and magnetic properties of the above mentioned materials have led to new constructions of magnetic circuits and accompanying electronics, and also to new methods of measurement of their magnetic properties.

The latest version of the Dynamic hysterczigraph is described in [1]. The instrument uses a digital oscilloscope for simultaneous sampling and averaging; the induced voltage is numerically integrated; and the hysteresis loop and sample parameters including power losses are calculated. The instrument software, written in Turbo Pascal and С languages in the MS Windows environment, allows easy modifications and graphic data handling. Another version of the virtual instrument was created in the LabView environment [2]. The improved version of the instrument, which is under development, is using lC-bit/1 MHz IOTECH model ADC 488/SSA synchronous sampling unit; the aim is to increase the instrument precision, especially for the evaluation of power losses. The excitation arbitrary waveform will be automatically adjusted so that the sinusoidal magnetic induction waveform will be reached as required by the standard 1EC methodology. The high-frequency instrument power amplifier necessary for core excitation is under development. The aforementioned instrument will allow us to measure precisely the magnetic parameters of the toroidal samples at high frequencies, as required for the design of power chokes for switch-mode power supplies.

The concepts used in software packages created for magnetic measuring instruments are discussed in [3]. The innovative Complex permeability meter is created as a virtual instrument in the Labwindows CVI environment. The hardware consists of a Digital Signal Processing Lock-in Amplifier, a V-MOS excitation power amplifier and computer-controlled high-frequency resistor, and a switching box of novel construction. The instrument frequency range has been extended up to 100 kHz.

The industrial Initial Permeability Meter was developed on a contract basis for ABB Brno. The instrument is used for input quality checks of the toroidal and С cores. In order to eliminate the time-consuming winding of each measured sample, industrial permeability meters usually use special measuring fixtures. Both the excitation and measuring windings are created by a single multi-conductor cable; the multi-pole connector allows us to break the winding loop and easily insert the sample. Errors caused by a non-uniformity in the winding have to be taken into account in case of low permeability. Studies regarding the

709


errors created by desacomodation eíTcct and non-sinusoidal magnetization condition have been conducted [4]. The total instrument error achieved is well below 5 %.

Amorphous foils may be used for shielding purposes, because, unlike the permalloys, they may be formed without subsequent high-temperature annealing. Circular 1.2 m Helmholtz coil pair for shielding efficiency tests arc being designed and fabricated in collaboration with Development Laboratories in Poděbrady.

Magnetic field and field gradient sensors using amorphous magnetic materials exhibit excellent properties. Race-track fluxgatc sensors developed at CTU have a noise level below 7 pT rms (100 mllz to 10 Hz) [5]. Miniature sensors working on the same principle have an even larger sensitivity than Hall and anisotropic magnetorcsistance sensors [6]. The high electrical resistivity of the alloy used, allows us to increase the excitation frequency and also use the fluxgate magnetometer to measure AC magnetic fields [7]. Technology for producing the annular sensor cores from nanocrystalline material is under development.

Design and error analysis of the amorphous core instrument current transformer proved another field of use for these materials. Preliminary measurements of the nanocrystalline toroidal cores have shown that the almost constant and relatively high permeability of these materials allow us to built instrument transformers with a large dynamic range. Because the saturation induction of nanocrystallinc materials is much larger than that of both cobalt-based amorphous materials and permalloys, the resulting core volume may be significantly lower. Another advantage of iron-based nanocrystalline materials is the low cost of the raw materials used in their production.

References: [1] RIPKA, P. - SMOLÍK, P. - ROZTOČIL, J. - KAŠPAR, P.: Dynamic Digital Hystcrc-

sisgraph Imeko World Congress, Torino, Italy 1994, pp. 752-756. [2] RIPKA, P. - ROZTOČIL, J. - KAŠPAR, P.: Magnetic Measuring systems National

Instruments European User Symposium, Munich 1994 [3] ROZTOČIL, J. - DRAXLER, K. - RIPKA, P. - KAŠPAR, P.: Software for Magnetic

Measurements Magnetic Measurements conference, Bratislava 1994, pp. C8-70 [4] DRAXLER, K. - RIPKA, P. - KAŠPAR, P.: Measurement of AC permeability of closed

samples Magnetic Measurements conference, Bratislava 1994, pp. 24-26 [5] RIPKA, P.: Race-track fluxgatc sensors Sensors and Actuators A, Vol. 37-3S, 1993,

pp. 417-421 [6] RIPKA, P.: Magnetic sensors for industrial and field applications Sensors and Actua

tors A, Vol. 42, 1994, pp. 394-397

This research has been conducted at the Department of Measurement as pari of the research project "Amorphous and nanocrystalline materials in electrical engineering" and has been supported by GACR grant No. 103/93/1197.

710


Fluxgate magnetopneumometer P. Ripka, D. Nemec, J. Roztočil, P. Kašpar

CTU, Fac. of Electrical Eng., Dept. of Measurements Technická 2,166 27 Praha б

Key words: magnetic sensors, pulmoral diagnostics, magnetopneumometry

Magnetopncumometry is a pulmonar diagnostic method based on the measurement of a remanent field of the lungs after magnetization by an external DC magnetic field. The prime aim is to detect the amount and eventually spatial distribution of the magnetic contaminants respirated by the lungs of workers such as miners, welders and grinders who are exposed to dust and fumes.

The fluxgate single-core race-track (oval) gradiometric sensor developed in our laboratory [1] is sensitive enough to replace SQUID magnetometers in most applications. The sensor resolution is 150 pT/cm for a 3.75 cm gradiometric base which corresponds to the field gradient created by 0.1 g of magnetite homogenically deposited throughout the whole volume of the lungs (when measured 2 cm from the skin surface). Such sensitivity is sufficient to detect deposits of iron and steel dusts and welding fumes.

We have measured samples of dust extracted post mortem from the lungs of eight black coal miners from various mines in the Czech Republic [2]. The susceptibility was measured using the bridge method: measured values were widely dispersed from 10E-6 to 10E-3. The samples were then magnetized in the DC field of 1 T and the remanence of the samples was measured using a rotation coil magnetometer.

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The variation of the individual values was again very high: the measured values varied from 50 nT to 10 000 nT,.while the correlation between the remanence and susceptibility was strong. The results have shown that the magnetic fraction represents, in this case, only a small part of the total dust load; the measured results should therefore be scaled using the reference samples collected from the particular working environment.

709

BIOMEDICAL ENGINEERING SECTION

The computer-controlled system for mo. .ling the remanence of large samples was developed and constructed. The system hardware consists of the fluxgate gradiometric sensor, excitation and measuring electronics, and a low-noise 20-bit compensation current source (Fig.l). The sensor also measures the homogeneous field component; the base field in the sensor axis is automatically compensated by the system and the field gradient is then measured. The software was written using Labwindows. The above mentioned virtual gradiometer was used for the measurement of dried lung tissue samples [3]*, Fig. 2 shows the gradients measured on various lung samples and corresponding mass of the extracted dust.

The measurements of the magnetization curves of both the tissue and dust samples arc prepared in collaboration with the Institute of Physical Metallurgy, A VCR in Brno using the Vibrating Sample Magnetometer. Future activities will include the design of the magnetization apparatus for in vivo measurement. The aim is to develop the instrument for on-site screening of workers such as grinders, miners and welders, exposed to dust or metal fumes.

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200

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Fluxgate Magnetome-

References: fl) RIPKA, P. - DRAXLER, K. - KAŠPAR, P. - SEDLAČEK, M.

ttrs and Gradiomtiers Workshop CTU 199-1, pp 165 (2) RIPKA, P. - BLAHA, J. - JERABEK, J.: Fluzgate Gmdiomeler for Magnetopncu-

mographyProc. Imeko World Congress, Torino, Italy 1994, p. 1527-1531 [3) BLAHA, J. - RIPKA, P. - PODLESÁK, J. - JERABEK, J.: Measuring system for

Study of the Micromagnelie Properties of Various Biological Objects Abstract book of the BEMS conference, Copenhagen 1991, p.IOC

This research has been conducted at the Department of Measurement CTU as part of the research project "Magnetopneumomclry" and has been supported by CTU grant No.38195.

71П

Section 14

ENVIRONMENT

&

ITS CREATION

WORKSHOP 95 ENVIRONMENT & ITS CREATION

MODEL OF NATIONAL INFORMATION SYSTEM OF THE ENVIRONMENT

J . Kolár

CTU, Fac. of Civil Eng. , Dcpt. of Mapping & Cartography Thákurova 7, 16G 29 Praha G

Key words: GIS, remote sensing, environment

The key factor in the relationship between man and nature is the evaluation and approval of particular actions or activities that society makes in the natural environment. Acceptance of ecological arguments during this process depends on the quality of information used for the approval of proposed plans.

Information about the environment is of two basic types:

• information about components of the environment and the state of the environment expressed by qualitative or quantitative descriptions of selected physical, biological or chemical parameters,

• information about causes and conscnquenccs of man's activities in nature, a forecast made through theoretical models presenting the state of our knowledge of natural processes.

The first category is a result of environmental monitoring. Captured data are processed in order to obtain needed information. The measurement usually takes place on the spot. The extrapolation of measurement results for larger areas is not a simple task. An important complementary method is remote sensing technology. Satellite data acqusition has spatial characteristics and covers large areas. Observation of the same region is repeated in intervals of hours up till weeks. Another advantage of remote sensing data is their digital format. As a raster image such data sets can be easily imported into a GIS database.

Modelling is a tool for elaboration of the forecast. This more sophisticated source of information about the environment plays an important role in every decision process or risk assessment.

Both categories are spatially dependent, i.e. they are geographically connected. They are closely tied and they enter together into the decision process. The volume of such information is quite huge which makes traditional means of analysis difficult to use. The best tools for storing, archiving, handling and analysis of the environmental information are modern methods of geoinformation system (GIS) accompanied by remote sensing as a complementary method to conventional data gathering.

An important feature of the geoinformation system on the environment (GISE) at a national level is the large number of its potcntional users. Their needs and demands concerning the content of the database would be rather different from each other. This leads to an enormous volume of data to be stored in the system. It is not realistic to plan to build up such a system as one physical unit. Moreover, not all of the users are ready to define their needs. Consenquently, it does not allow for the specifation of the database content and type of outputs completely.

713


The present situation of the environment information structures is characterized by a rather large hetcrogenity of activities. Many information systems arc under development in different fields of application. That implies an increased measurement of redundancy and duplication among various systems. Also, different spatial coordination systems for localization of data are used and data are of different scales and accuracy. Many developers are simultaneously users and they are faced with many new problems and obstacles under the process. However, the effective implementation of the environmental aspects into decisionmaking of governmental bodies on all levels requires sounded arguments based on all existing and reachable information.

The basic approach for the proposal of the national environment information system is standing on two main requirements:

1. The information system will be built up on a platform of GIS technology which sets means of communications with the system.

2. Instead of creation of one central database of mammoth volume the system will be developed as a virtual GIS using a compact network connection of contributing GIS in various institutions.

The virtual GIS will be run by professional operators who will negotiate information transfer from the system to the user. Content of the virtual GIS will be defined by all users' demands. To reach this goal technically, the network of existing thematic or regional oriented databases or GIS in various institutions must be created. The access into every database will be filtered by access selectors allowing approved type of access only. The filters will be defined to fulfil all information requirements relevant to the national information system. Generally, a certain limited subset of each real institutional dt4tabase will be defined by the fillers for implementing the virtual national GISE. Users' needs not covered by any of the existing databases will be supplied from an additional database. Such a database will be created and updated directly by the institution of the national system. The other data of networked GIS will be updated by and in iesponsibility of their developers.

This realization of this concept lias to be driven by the Ministry of Environment where the time schedule should be prepared and intialial steps should be taken.

This research has been conducted at the Department of Mapping and Cartography as pp-t of the research project "Application of new remote sensing methods to environmental ei,~.uation" and has been supported by internal grant of the Fac. of Civil Eng. of CTU No. 15317.

714


SAMPLING PROBE FOR MEASURING OF CLASSIFIED EMISSION

J . Hemerkn, L. Mares

CTU, Fac. of Mechanical Eng., Dept. of Environmental Engineering Technická 4, 166 07 Praha 6

Key words: emission measurement, virtual impactor, representative sample, wall losses, heavy metals

The main goal of the project was design, realization and experimental verification of changes of a virtual impactor - a sampling probe for measuring classified emission with particle cut size 10 /iin - for reduction of particle losses on the internal walls of the impactor. The project was of a research and development character and followed the works done at the Department of Environmental Engineering in the last several years when the virtual impactor with particle cut size ai,m in the range of values from 4,2 to 12,8 /trn for gas temperature 20 °C and particle cut size from 4,7 to 10,8 /im for gas temperature 150 "C has been developed [1].

The virtual impactor classifies the sample into fine and a coarse fractions according to a fractional efficiency curve, which can be characterized by means of the particle cut size a\,m- The analysis of experiments from the year 1992 has shown that the relative particle losses on the walls of the impactor in the coarse fraction reach up to several tens of per cent for higher values a\<m (lower flow rates) and losses gradually decrease down to 5 % for smaller values of alim (higher flow rates). The relative wall losses in the fine fraction range from 1 to 19 % with no evident dependence on the value of a\<m.

When the impactor operates with the particle cut size 10 /mi, the relative wall losses in the coarse fraction Ег,н, estimated from the measurements with three different test dusts (fly ashes), range from 14 to 30,5 % and corresponding losses in the fine fraction Ezj range from 8,7 to 13,9 %. The particle losses in the coarse fraction seem to be too high for the representative samples for the subsequent chemical analysis of particles, especially the analysis of heavy metals.

From the analysis of wall losses follows, that for the reduction of wall losses of the impactor operating with the particle cut size 10 /un the flow rate through the impactor Vo [w3/s] and outlet nozzle diameter Do [m] hfive to be increased. For this reason the functional parts of the impactor were reconstructed so that the outlet nozzle diameter DQ was increased to 10.10"3 m and the corresponding changes in dimensions of the impaction nozzle and the distance between outlet and impaction nozzle were realized. After these changes of dimensions of parts in the classification zone, the flow rate through the impactor Vo could be increased by about 95 %.

The experimental verification of changes of the impactor was realized at the laboratory test rig with a laboratory temperature of about 2S °C (the corresponding flow rate through the impactor V0 = 0,657.10-3 n?3/s), with three different sampling tubes (tip diameters D, = 7,289; 9,663 and 11,390 mm) and three corresponding gas velocities (uj. = 15,6; 8,90 and 6,39 m/s). As the laboratory test dust three different fly ashes with mass medians 7; 10 and 13 /mi were used. Together 23 individual tests were realized.

715

WORKSHOP 95 ENVIRONMENT к ITS CREATION

If follows from the results of measurement that in the coarse fraction the aritmetical mean value of the relative wall losses Е™Цап, calculated from all 23 measurements, gives a value of 13,38 % and the sample standard deviation an-i is 9,47 %. In the fine fraction the corresponding values of the relative wall losses are E™jan = 9,67 % and an-\ - 3,03 %.

Comparing these results with the experimental data found earlier with the previous type of the virtual impactor and operating with the particle cut size aj,m approximately 10 /im H 's obvious that the wall losses in the coarse fraction were reduced to a reasonable level. 1° most cases the sample of the coarse fraction (particles separated on the minor flow filter) can be therefore regarded as a representative sample. The wall losses of the fine fraction were slightly reduced and the sample of the fine fraction (particles separated on the major fl°w filter) can be also regarded as a representative sample.

The experimental data of wall losses have relatively high value of the standard deviation. The wall losses and the classification process itself are probably influenced by the shape of the sampling tube, which changes the flow pattern in the classification zone of the impactor. This question will be investigated next year.

The main goal of the project for the year 1994 was fulfilled. The results represent the part of the research and development of the sampling probe for classified emission with the particle cut size 10 /im.

References: [1] HEMERKA, J. - PROCHÁZKA, P.: Particle Losses on the Walls of a Virtual Im

pactor. Proceedings of the 3rd Meeting of the Task Force on Heavy Metals Emissions. p. 83 - 84. Berlin 1993.

This research has been conducted at the Department of Environmental Engineering as part of the research project "Sampling Probe for Measuring of Classified Emission" and has been supported by CTU grant No. 08 28169.

716

С2.Э5 35ЭЭО WORKSHOP 95 ENVIRONMENT fc ITS CREATION

SETUP FOR MONITORING OF A RESPIRABLE AEROSOL

J. Král, J. Voltr

CTU, Рас. of Nucl. Sci. к Phys. ling., Dept. of Physical Electronics V Holcšovičkách 2, 180 00 Praha 8

Key words: air pollution, respirable aerosol, aerosol sampler, P1XE

People spend most of their time in in-door environments of various types. The quality of air, polluted by products of their aclivily,may be of great importance in relation to their health. By breathing, one is in immediate contact with air, including its polluting components. Besides gassy and liquid pollutants, air bears solid particles which may have harmful biological effects. Airborne particles contain a variety of heavy elements, some of which may be poisonous in human organism. Danger from particulate matter inhaled into a human body depends on the site of its deposition and its nature. While large particulates are trapped in the nose and upper airways the smaller particulates penetrate deeper and may be deposited in the alveoli. To follow the element composition of the rcspirablc particles which can penetrate to the unciliatcd airways it is necessary to collect the rcspirable fraction of aerosol and then to analyse it with a sufficiently sensitive analytical method.

Having at our disposal a'facility for PIXE analysis efforts have been devoted to the development of equipment and preparation of conditions for sampling and analysing respirable fraction of aerosols.

A sampler has been designed and constructed which collects the fine rcspirablc fraction of aerosol, separated from the rougher particulate matter. The separated fraction is collected on a Nuclepore membrane filter with pores of 0.4 Srn diameter. The course fraction is stopped in an impactor, which is placed in front of the filter. The impactor has round nozzles situated equidistantly on a circular line against an annular impaction plate. The impaction area of the plate is covered by a slight layer of vacuum fat, to be adhesive to the particulates deposited. Using air flow from 5 to 15 1/min the cut-off size of the particulates captured may be set from 7.5 to 4.5 Sm of hydrodynamic diameter, respectively. Considering shapes of the impactor characteristics [1] and the respirable convention [2], essential part (or even all) of the respirable fraction may pass to the collecting filter, accompanied only by some finer part of thoracic fraction. The deposit on the filter, i.e. collected sample of a respirable aerosol, is on a circular area of 20mm diameter. To collect suitable samples, collecting time may be from minutes to tens of hours; it depends on the cleanness or degree of contamination of the atmosphere studied. The filter with collected sample of aerosol is analysed as a thin target by PIXE method, using the equipment developed in the past years [3] with protons of 2 MeV energy. The proton beam bombards the sample along its normal and X-rays emitted by the sample enter the PGT Si(Li) detector in the direction of 120 degrees relative to the proton beam. An absorber between the sample and the detector stops backscattered protons and is used to modify the intensity of spectrum lines. The strong low energy lines are attenuated in favour of the weak more energetic ones of heavier elements. A combination of a thin full filter and a thick perforated one, known as "funny filter", is tested and will be used for aerosol analyses. The equipment is calibrated with the use of

717

WORKSHOP 95 ENVIRONMENT fe ITS CREATION

calibration standards of Micro Matter Corp. and collected spectra are treated with the use of GUPIX software package [4].

Currently the new sampler is being used to collect aerosol samples, to gain experience with its operation and original data on aerosol from different in-door localities.

The authors acknowledge the valuable consultation on rcf.[2] of Dr. Ilurych from the National Institute of Public Health and careful manufacturing of the new sampler by Mr. Skutina.

References:

[1] FUCHS, N. A. et al.: Aerosol Impaclors (A Review), in Fundamentals of Aerosol Science (T.D. Shaw, ed.). John Wiley and Sons, New York 1978.

[2] Workplace atmospheres - Size fraction definitions for measurement of airborne particles. European Standard EN481, CEN, Brussels 1993.

[3] KRÁL, J. - VOLTR, J. - POTOCEK, V. - SALOMONOVlC, R.: PIXE Analysis -Equipment and Techniques CTU Seminar 94, Part A, CTU Prague 1994, p.65

[4] MAXWELL, J. A. - CAMPBELL, J. L. - TEASDALE, W. J.: The Guelph PIXE Software Package Nucl.Instr.and.Mcth. [Ш, (19S9), p.21S

77ns research has been conducted al (he Department of Physical Electronics Faculty of Nuclear Science and Physical Engineering as pari of (he research project "Monitoring of Heavy Elements in a Respirable Aerosol of Indoor Environment" and has been supported by CTU grant No. 8209

718

WORKSHOP 95 ENVIRONMENT fc ITS CREATION

APPLICATION OF RADIOANALYTICAL METHODS FOR ENVIRONMENTAL

MONITORING L. Musílek, T. Čechák, J. Král*, H. Th. Wolterbeek**, P. Kuik**

CTU, Fac. of Nucl. Sci. & Pliys. Eng., Dcpt. of Dosimetry & Appl. of Ionizing Radiation Břehová", 115 19 Praha l

*CTU, Fac. of Nucl. Sci. & Pliys. Eng., Dept. of Physical Electronics V Ilolcšovičkách 2, 180 00 Praha 8

**TU Delft, Interfaculty Reactor Institute, Dept. of Radiochcmistry Mekelweg 15, 2629 J В Delft, The Netherlands

Key words: environmental pollution, bioaccumulation, X-ray fluorescence, PIXE, lichen samples, bark samples, soil samples, a real monitoring

The preliminary study of the application of radioanalytical methods for bio-monitoring of air pollution of the area of the Czech Republic had shown some potential problems, connected with the broken altitude profile of the country [1,2], which were not taken into consideration in similar measurements in the less complicated terrain of, e.g., The Netherlands [3,4].

Therefore it was decided to provide a more detailed testing of the reasons for the high local variations which had been found. This was done by selecting very typical locations for sampling and measurement and taking large sets of samples. This stage of the project is the subject of activities in 1994.

Sampling sites were selected as follows: 1) Various sides of an isolated hill in flat country (Rip). Because of prevailing westerly

winds some shielding of trees growing on the eastern side can be expected. 2) Various trees from a small area (within 100 in) in very flat country (Chrást near

Všetaty). Samples were taken from oaks, pines and false acacias to show the difference in absorption ability of various species.

3) Randomly distributed places in a 10 x 10 km square in a moderately hilly area (near Rakovník). This sampling represents a typical situation and is intended to give information about the anticipated uncertainty of results, if the 10 x 10 km square is used as a basis for monitoring the whole country.

4) A few places in hilly areas (Lužické hory). Comparison with case 3) gives information about the influence of the landscape profile on the reliability of results.

Oak bark is considered as a biomonitoř, because more sensitive lichens used in some studies (e.g., [3.4]) are not available in some areas. Comparisons with other species in 2), especially with pine, can help cover some highland regions (oak prefers a warmer climate). Soil samples were also taken in all places to enable correlation of the,contaminating elements in soil and bark. Epiphytic lichens can supply auxiliary information in the localities in which they still grow.

719


Epiphytic lichens also serve as a biomotiitor in another part of the project which traces the contamination into the past. For this purpose a collaboration with the National Museum in Prague has been initialed. The Museum's herbarium houses 100 year old lichens, and from some locations (Divoká Šárka, Mariánské Lázně) samples exist from various times. Comparison of the content of contaminants in these old samples and samples collected this year for the purposes of our project dan produce data about the development of contamination caused by the continuing industrialisation of the country.

Three various radioanalytical methods arc applied for the measurement. 1. Radioisotope X-ray fluorescence analysis with 55Fc, 238Pu and J'"Am sources. This

method is relatively simple, but because of lower sensitivity it is used mainly for larger volume samples of bark and soil; the volume of lichen samples is often too small.

2. Particle induced x-ray emission, excited by protons from the Van de Graaff accelerator. This method is more expensive, brings strict demands for sample preparation, but needs only a small volume of samples which is advantageous when dealing with historical lichens from the National Museum collection.

3. Instrumental neutron activation analysis is carried out at the 2 MW research reactor of the IRI TU Delft. The sensitivity of this method allows the use of small samples and completes the set of methods so that any result can be obtained by two independent systems.

The measurement and evaluation is still in progress and only preliminary results arc available. Nevertheless, even from these some recommendation can be made for the selection of sampling sites to avoid non-rcprcscntativc readings.

References:

[1] MUSlLEK, L. - СЕСНАК, T. - WOLTERBEEK, II. T. - KUIK, P.: Study of environmental contamination in the Czech Republic using radioanalytical methods. 6th Int. Symp. Radiation Physics, Rabat (Morocco), July 18-22, 1994.

[2] MUSÍLEK, L. - СЕСНАК, T. - WOLTERBEEK, II. T. - KUIK, P.: Preliminary study of environmental contamination using radioanalylical methods. In. Proc. of the CTU Prague Seminar 94, Seminar 94 - Environmental Engineering, p. 33-34

[3] SLOOF, .1. E. - WOLTERBEEK, II. Т.: /1 national monitoring survey using epiphytic lichens as biomonitors of I race element air pollution. Liclienologist, 23(2), 139-165, 1991

[4] SLOOF, J. E.: Environmental lichenology: Uiomonitoring Iracc-clemenl air pollution. PhD thesis, IRI TU Delft, September 1993

This research has been conducted at the Department of Dosimetry and Application of Ionizing Radiation as a part of the research project "Application of ionizing radiation for measurement of environmental contamination" and has been supported by CTU grant No. 48139 and GA C'R grant 202/9/,/0868.

720


CONTAMINATION OF SEDIMENTS BY URBAN STORM DRAINAGE

Z. Hnndová, M. Liška*

CTU, Fac. of Civil Eng., Dcpt, of Sanitary Engineering Thákurova 7, 166 29 Praha 6

*Water Treatment Plant Zelivka, Hulicc, 258 22 Zruč n. Sáz.

Key words: urban storm drainage, heavy metals, sediments, macrozoobenthos

From the point of view of water supply, heavy metals and organic micropollutants are two of the major contributions to storm water pollution. The problems associated with this pollution include mutagenic, cancerous and chronic effects, and the effects on the ecosystem characteristics [1].

According to the adsorption of the mentioned pollutants on the fine particles [2] Pb, Cd, Ni (typical for urban storm waters) was estimated in sediments from the receiving water body. In addition, concentration of this heavy metals was estimated also in macrozoobenthos as indicator of food web contamination. The analysis of polyaromatics hydrocarbons (PAHc) in sediments is still in progress.

The experimental catchment Kbely with the recipient Vinořský creek are schematically shown in Fig.l. The area of the catchment is 14,2 sqkm, the total annual precipitation is 540 mm. The average recipient flow before WWTP is 20 1/s and increase to the 48 1/s due to effluent from the wastewater treatment plant (WWTP).

Fig. 1: Kbely catchment

Discharges of combine stormwater overflow (CSO) are designated by capitals, sampling points by numbers. The new nitrogen removal WWTP for the urban areas Kbely and Satalice was put into the use in the spring of 1994.

721


Due to the operation of the new S/V stormwater separator in the WVVTP the function of the CSO-A and CSO-C and CSO-D was finished in July 1994. The CSO-B (storm drainage of airport area) is still functioning.

Concentration of Pb, Cd and Ni in sediments and Tanypodinae are presented in the Tab.l. Changes in Pb concentration indicate decreasing pollution from urbanized stormwa-tcr.The high level concentration of Cd and Ni in the benthos organism from the sampling point 2 shows that very important sources of pollution, are caused by storm drainage from the airport area.

Sampling point

1 la 2 3 4 5 6

Pb (mg/kg)

S -

114 106 -

164 163 -

Tl 8,6

5,2 7,2 14,0

. 29,1

T2 0,5

0,8 1,8 1,0 3,7 4,8

Cd (mg/kg)

S -

48,0 78.3

-208,0 35,8

-

Tl 0,3

124,7 95,1 104,0

. 23,1

T2 0,2

180,8 61,5 64,5 7,3 6,4

Ni (mg/kg)

S -

56 100 .

142 54 -

Tl 5,0

V 8,0 7,8

" Л .

T2 6,2

258,8 12,9 3,3 4,2 9,0

S-sediments 14.9.93 Tl-Tanypodinae 7.4.94 T2-Tanypodinae 8.9.94

Tab. 1: Concentration of heavy metals in sediments and macrozoobenthos

The results of sediments and benthos analysis indicate a signification of combine sewer overflow control and stormwater management for ecological consequences and health risks.

References: [1] HOUSE, M. A. et al.: Urban Drainage - Impacts on Receiving Water Quality

Wat.Sci.Tech. Vol.27, Nol2, pp.U7-158, 1993 [2] HAND0VÁ, Z.: The Storm Water Pollution in the Integrated Urban D rainage System

Proc.Conf.: New Requirements for Structures and their Reliability, pp. 191-196, CTU, Fac. of Civil Eng., Prague 1994

This research has been conducted at the Department of Sanitary Engineering as part of the research project "Pollution of Urban Storm Waste Water by Anthropogenic Pollutants" and has been supported by GAČR grant No. 103/93/0637 and TU grant No. 1ЦЮ

722


HYDRODYNAMIC TOOLS FOR RIVER CATCHMENT ANALYSIS

P. Ingeduld, E. Zeman, S. Vaněček

CTU, Fac. of Civil Eng., Dept. of Hydraulics & Hydrology Tlmkurova 7, 166 29 Praha 6

Key words: Hydroinformatics, Unsteady Flow, Mathematical Models

Today there is a need for an engineering software package for two dimensional flow analysis, giving all information about water velocities and water levels distribution, solving both problems of steady and unsteady flow in rivers and in adjacent flood plains. The modular structure of such a tool may be based on a database-oriented input part with QBE (query by example selections) and SQL Selection facilities, graphical modules for the definition and checking of input data and for providing a, fact engineering approach to the presentation of output data and on separate numerical modules.

Л prototype of such a tool, based on a highly modular structure working even on different hardware platforms, coupling a database application, graphical post-processors and a numerical simulator is presented here.

Л data base application has been created for data collection from field experiments. All collected data should be validated and pre-processed using the application in order to maintain the data describing measurement courses, cross-sectional data, velocity fields at cross sections including point velocity information from a current metering campaign and describing roughness and water stages etc. The data has been saved with detailed information about the space co-ordinates and the time of data sampling.

Additional data based on a relevant evaluation procedure may be included into the specific files; data such as longitudinal slope, resulting discharge from current metering, roughness coefficient etc. The data base application enables the user to save and relate a graphical plot and/or a colour photo image. Retrieval from the data base is quite simple and the exporting facility is a very important feature. It is expected that new standard methods which have been tested during the project will be later transferred directly into the data base application. The application has been developed within the WinI3ase602 system. It is expected that after completion of all the field measurements and final validation of collected data from the specified catchments the data in data base format will be transferred to the Water Board. The described application should serve for other potential users as a principle methodology.

Analyses have beem carried out concerning the methodology of specialised applications performing 2D hydrodynamic modelling of rivers and flood plains. A partial conclusion was suggested to prepare a methodology which allows the user to consider a river topography which is very close to reality. The actual topographies for 2D applications related to the grant requirements and the researchers needs can be specified by using a higher operating system (e.g. UNIX). The FLUVIUS package was tested on a UNIX platform without any changes in the computational algorithm. The computational part of the package was directly ported onto the new UNIX environment with only a few negligible changes to system dependent parts. Numerical computation by a workstation allows the user to use a larger and smoother computational grid and to have in this way all results available faster and

723


with more detail; crucial for rcvitalisation studies unavoidable. The details of water stages and velocity fields provide the researchers with boundary conditions for the methods which are usually applied to the details in the model (especially in the case of meandering).

The results of tests of the 2D modelling application within the operating system UNIX gave the expected evidence of decreasing computational time substantially and enabling the use of parallel simulation runs. An evaluated methodology for the manual transfer of validated data prepared in the DOS environment exists, data can than be used for simulation within the UNIX environment in the 2D modelling domain is finally transferred as results into the DOS environment for presentation.

Currently, selection of a relevant domain for test purposes in the field is takong place where some measured data has already been available. The following figure (Fig.l) shows the working results of the 2D unsteady How simulation on a grid size of 1000x500 points.

Fig. 1: Map of Water Depths

References: [1] ZEMAN, E. - VANĚČEK, S. - INGEDULD, P.: Use of a mathematical model Flu-

vius for numerical simulation of unstady flow in ňvers and flood plains International Conference IAHR, Madrid, 1991

[2] ZEMAN, E. - VANĚČEK, S. - INGEDULD, P.: 2D Mathematical Model for Simulation of Unsteady Flow in Rivers - An Element of Decision Support System in Aquatic Environment The Internetional Conference on Interaction of Computational Methods and Measurements in Hydraulics and Hydrology, held in Budapest, Hungary, 25-29 May, 1992

This research has been conducted at the Department of Hydraulics and Hydrology as part of the research project "Revitalizacion of Trained Rivers" and has been supported by CTU grant No. 1 8075.

724


SIMULATION MODELS OF TRANSPORT PROCESSES IN A WATERSHED

T. Dostal, J. Vaška, K. Vrana

CTU, Fac. of Civil Eng., Dept. of Irrigation & Drainage Thákurova 7, 166 29 Praha 6

Key words: soil erosion, transport processes, simulation models

qManagement of surface runoff and transport processes in a watershed creates the basic conditions for its ecological stability and for the sustainability of the quality of its water resources. Soil erosion and the transport of sediment and chemical pollutants are the results of rainafall-runoff events. Besides the on-site effect on soil productivity, soil erosion and sediment transport have significant negative impacts on the surface water resources quality.

Various methods can be used for the assessment of soil erosion hazards and for the design and for the evaluation of soil and water conservation measures. Empirical methods have been used over the last few decades for estimating an erosion hazard and for making hydrological assessments (e.g. Universal Soil Loss Equation, Curve Number Methods, etc.). Recently, physically-based mathematical simulation models of hydrological, erosion and transport processes have begun to be used extensively. A great number of simulation models have been developed for different applications and for various conditions in the USA and in some European countries. The main objective of the research project was validation, testing and sensitivity analysis of selected simulation models and recommendations for their applicability in the conditions of the Czech Republic.

The following simulation models were considered for validation: a) watershed models - MULTSED (Multiple Watershed Stormwater and Sediment

Runoff Simulation Model - USA) - ANSWERS (Areal Non-Point Source Watershed Environmental Response Simulation - USA) - AGNPS (Agricultural Non-Point Source Pollution Model - USA)

b) field (single slope) models - SMODERP (Simulation Model of Erosion and Runoff Processes - CR) - WEPP (Water Erosion Prediction Project - Hillslope Profile Version -USA).

The data from two pilot watersheds were used for validation of the models and for sensitivity analysis of the principal input data (climatic, morphological, soil and vegetation data). The first watershed used was Černici (a part of the Cechticky Brook watershed, Pelhřimov district) with a size of 1.5 km2, the second one was the Sklare watershed (a part of the Polecnice watershed, Česky Krumlov district) with a size of 2.52 km2. Both pilot waterheds were small agricultural ones.

The final recommendations can be summarized as follows : a) MULTSED - the validation showed, that the model cannot be recommended for

application to a small watershed condition due to a high simplification of the watershed geometry and properties. Further testing of the model for macro-scale conditions is suggested.

b) ANSWERS - the model provided an acceptable simulation of hydrologie and erosion processes after being calibrated for the pilot watersheds conditions. A detailed sensitivity analysis of the model input data is proposed. It was recommended to connect the model with

725


a GIS for the input data pre-processing and for presentation of the simulation's outputs. The model is recommended for verification on larger watersheds too.

c) AGNPS - the advantage of this model is the simplicity of the input data preprocessing, good graphical presentation of the model outputs and adequate simulation of chemical transport. The model provided an acceptable simulation of hydrologie and erosion processes after being calibrated with the pilot watersheds conditions. One disadvantage of the model application is the use of American customary units for ť г input and output data. The model is recommended for further validation and for a detailed sensitivity analysis.

d) SMODERP - this model has been calibrated well for determination of critical slope length and overland flow characteristics. The model lias been extensively used for erosion hazard assessment in various regions with various natural and land use conditions in the Czech Republic; it was also validated in Japan. The paper recommends the enhancement of the model for watershed conditions.

e) VVEPP - hillslope profile version; VVEPP is a joint effort of several US agencies dealing with soil and water conservation to replace the empirical prediction methods witli a modern process-oriented tool. The hillslope profile version provides extended information on on-site and off-site effects of overland flow and erosion processes that are used for selection of the best management practices. The climatic data for the model are generated by a climatic generator which has not been made available for simulation of the Czech Republic's conditions yet. Therefore, a quantitative validation of the model has not been possible. The paper recommends concentration of the research effort onto building-up of the climatic generator for the Czech Republic.

This research has been conducted at the Department of Irrigation, Drainage and Landscape Engineering as part of the research project "Simulation Models of Transport Processes in a Watershed" and has been snppoi-tcd by CTU grant No. 18150.

726


IMPROVEMENTS OF RATING CURVES USED IN HYDROLOGY BY APPLICATION OP

MATHEMATICAL MODELS

J. špatka, E. Zeman

CTU, Fac. of Civil Eng., Dcpt. of Hydraulics к Hydrology Thákurova 7, 166 29 Praha 6

Key words: Hydrology, Hydroinfoimalics, Rating Curves, Mathematical Models

The authors of the paper have been dealing with quite an interesting research topic. They focused on accuracy and derivation of rating curves which are used in hydrology, but in a less traditional way. The research work has been carried out with the support of the Grant awarded by the Civil Engineering Faculty Nr. 14111/2059.

The objectives of the research activity were set-up in response to the an overall demands for improvement of general knowledge and increment of accuracy in derivation of a standard rating curves, gauging cross sections in open channel network. Our main interest has been focused on flood conditions when an extreme load imposes on river channels, from a hydrodynamic point of view. The extreme discharges are influenced by various parameters which leads to an uncertain relationship between stages and discharges at nearly all gauging cross sections. There can be observed a sediment transport phenomena which badly influences the development of the Q=f(II) relation in extreme conditions. Л seasonal variation of vegetation in river channels and banks has it's impact on resistance characteristics and the velocity distribution at the cross section plays an important role in the rating curve derivation.

There is a clear methodology expected as a result of the research activity, which takes into account all the important factors influencing derivation of rating curves. The methodology will be based on investigations which will be executed by means of mathematical models, enabling the researchers, and later users, to simulate the extreme conditions in order to derive rating curves at selected profiles as accurately as possible, even under conditions of severe flood.

It is well known that the accuracy of rating curves is far from being accurate under extremes conditions because the extreme events are rare and hydrologists have to wait for real events in order to have a chance to observe the required parameters.. If there are not enough events one has to extrapolate the recorded relation Q = f(H) outside the monitored interval where the rating curve can be rather misleading. The attention of the researchers has been focused on a suitable approximation of rating curves, at a known cross section, based on an additional knowledge of the all hydrodynamic parameters retrieved as results from simulation runs of mathematical models.

The project was planned in three phases. The first phase of the project was executed in the year 1994. The authors selected the most suitable gauging station in Mimoň on the Ploučnice river, where nearly all the hydrological data was available and the gauging station there was considered to be a instrumental for the monitoring system founded by the

727


Czech Hydrometcorologicai Institute. The cross section in Mimoň was selected from the list of available stations mainly for these reasons: A) there is located a permanent gauging station with a reasonable record period, B) there arc several recorded flood events in the cross section, C) the cross section of the gauging station is located in an specifically defined topography, where even extreme discharges arc concentrated in the valley, D) both ID and 2D mathematical models are applicable in the selected domain.

The preparatory works, data collection and pre-processing activities were all carried out there. A field experiment territory in Mimoň was identified, where initial field investigations were executed. The samples of bed materials were collected at 15 locations in the domain and material characteristics have been presented in the form of grain size distribution curves. A Digital Model of Terrain (DMT) has been prepared, which represents the base for ID and 2D mathematical models from a topographical point of view. All works aiming at setting-up both 2D and ID models will be completed by the end of the first phase of the project, in order to allow the researchers to examine all the possible hydrodynamic situations under given boundary conditions, leading into the required relation Q= f(II) at the selected cross section Mimoň. The MIKE11 package will be used for ID model set-up and for creating some of the necessary boundary conditions. The FLUVIUS package will be used for 2D simulation in the domain providing the detail velocity and discharge fields and the water stage development for the team of researchers. Several current metering campaigns were executed at the cross section Mimoň. The results from these measurements provided a very interesting output, confirming the influence of the vegetation on the river bed on velocity profile development. During the evaluation the recently completed software IIMShcII (1994) package was used, which has been designed for nearly on-line evaluation of velocity profiles, obtained by current metering. Video records were taken during the experimental activities providing all the evidence required. It can be concluded that the observed bed vegetation has its impacts on velocity profiles and sedimentation activities in the vicinity of the gauging station and basic assumptions of the authors concerning the accuracy of rating curves were indirectly confirmed, although the evidence has to be worked out in more details later.

The processing phase of all the collected data, preparation of hydrodynamic parameters and boundary conditions in domain for simulations by mathematical models in the second phase wll be finalised in 1995. The project will be completed and the required methodology will be formulated within the framework of conclusions on the project.

The necessary data for the research work is mainly supported by the Ohře Water Board and by the Czech Hydromctcorological Institute. An application for support of the activity was submitted from the Czech Grant Agency for the period 1995-1997.

References: [1] ZEMAN, E. - VANĚČEK, S. - INGEDULD, P.: 2D mathematical model for simulation

of unsteady floiu in rivers and flood plains - an clement of decision support system in aquatic environment Vituki, Budapest 1992

[2] Discharge and Velocity Measurements Short Course Zurich 26 - 28 August 19S7

This research has been conducted at the Department of Hydraulics and Hydrology as part of the research project "Monitoring of llydi-ological Parameters — a Validation and Accuracy Analysis of Rating Curves under the Extreme Conditions" and has been supported by CTU grant No. ЦП 1/2059.

728


MODELLING OF CONTAMINANTS MIGRATION IN THE REAL BODY USING A MODIFIED ID MODEL

D. Vopálka, К. Štamberg

CTU, Fac. of Nucl. Sci. & Phys. Eng., Rept. of Nuclear Chemistry Břehová?, 115 19 Praha l

Key words: modelling, contaminants, migration

The modelling of contaminants migration in porous media requires model descriptions of (i) hydrodynamics of liquid phase in both saturated and unsaturated layers and (ii) chemical behaviour of contaminants in the system studied mainly from the point of view of chemical equilibrium and kinetics in complex heterogeneous systems [1].

The basic one-dimensional partial differential equation describing the convective- diffusion mass transport in saturated zone with sorption and/or desorption was solved numerically using a finite difference method with Crank-Nicholson differential scheme. The linearization of the problem was achieved by means of an iterative method which eliminates the influence of the nonlinearity in equilibrium and kinetic dependencies. The program accepts the arbitrary form of these dependencies. Using this approach the tridiagonal shape of basic matrix was achieved, therefore the numerical solution is simple. An original method of the automatic choice of the time step was prepared which enables considerable acceleration of the computation. Tbe arbitrary shape of initial and boundary concentrations is acceptable by the program and the time and spatial dependencies in both phases can be computed for all desired conditions. The numerical stability of the program is very good.

When modelling the migration of contaminants through the soil layer it proved to be convenient to divide the computation into the sequential steps of the computation in smaller layers which correspond to the real pedological layers. Each layer was characterized by appropriate parameters such as height, void fraction, dispersion coefficient and parameters of interaction of contaminants with soil [2]. This layered model was further extended for the migration in such three-dimensional bodies in which the presumption of the existence of dominant direction of the flow of the liquid phase is acceptable. For the modelling the body under consideration was divided into layers, the section being perpendicular to the direction of the dominant flow. In addition to the parameters mentioned above layers are characterized by the mean surface of the cross section. The linear velocity of the flow in pores is simply determined from the knowledge of the total voluminal flow. The voluminal flow is on boundaries of the layer divided into two parts, the first one continues its flow in the studied body and the second leaves the body and penetrates the walls of the body. It is assumed that the ratio of these flows is the same as the ratio of maximal possible flows into corresponding areas which can be expressed as the product of appropriate efficient areas and filtration coefficients. The linear velocity in pores in the second and following areas can then be evaluated on the basis of this assumption. The model contemplates the total mass balance of the liquid and contaminants studied. The input signal is assumed to flow only into the first layer from the outside, the input from the walls of the body is not considered.

729


The output concentration from the body is determined as the weighted mean value of concentrations in portions of flow escaping out from the individual layers into the walls of the body. The sorption on the material of the wall is not mentioned. The described migration model in the body of the arbitrary shape enables us to convert the multi-dimensional modelling to the sequence of one-dimensional modelling. This approach can be recommended mainly when the structure of the body can be described by homogeneous layers and when the existence of the dominant direction of the flow is evident.

The model was used for modelling toxic metals migration in the uranium mill tailings near Dolní Rozinka. It is planned to deposit the waste after the decontamination of used galvanization solutions there. The body of tailings has a layered structure and the predominant direction of flow is from the pond, into which the waste will be deposited, to the dam below which the seepage waters are collected. The distance from the pond to the dam is about 100 m. The sorption of Zn, Cu and Ni from the technological water on the sediment in the tailings was studied in the laboratory [3]. The simulation of migration of mentioned contaminants in the studied body shows that the contamination of water in the surroundings of the tailings due to the deposition of galvanization silt will not be considerable even after hundreds of years. The working period of technology was assumed to be 30 years.

References:

[1] KNOX, R. С - SABATINI, D. A. - CANTER, L. W.: Subsurface Transport and Fate Processes. Lewis Publishers, Boca Raton 1993.

[2] VOPÁLKA, D. - STAMBERG, K.: Vrstvový model migrace kontaminantů půdou. Sborník přednášek semináře Geochemie a životní prostředí, Přírodovědecké fakulta UK, Praha 1993, pp. 74-75.

[3] STAMBERG, K. - BENEŠ, P. - VOPÁLKA, D. - LOUB, L.: Modelování migrace kontaminantů г neutralizačních kalů v odkalištích úpraven uranové rudy. Proceedings of the 2nd Intern. Conf. Environmental Impact Asscsment of all Economical Activities, Praha 1993, pp. 147-155.

This research has been conducted at the Department of Nuclear Chemistry as part of the research project "Modelling of Contaminants and Radionuclides Migration in Soils -Development of multicompont Models of Fundamental Processes and 2-D Models of Sorp-lion/Desorption Dynamics" and has been supported by CTU grant No. J82I5.

730


STUDY OF DISPERSION PROCESS IN A BED OF SEDIMENT

K. Štamberg, J. Škrkal, D. Vopálka

CTU, Fac. of Nucl. Sci. & Phys, Eng,, Dept, of Nuclear Chemistry Břehová?, 115 19 Praha l

Key words: dispersion, dispersion coefficient, sediment bed, Pcclct number

Theory. The behaviour of liquid phase while flowing through a porous bed of soils or sediments is given first of all by flow rale in the pores, height of the bed, size and shape of the soil or sediment granules and density and viscosity of the liquid. If the flowrate is extremely low, the molecular diffusion can also be important. In consequence of the influence of these parameters it does not deal with so called plug flow. Generally, the individual particles of the liquid phase have a different rate and therefore their holding time in bed is also different. This phenomenon forms, in the main, the basis of the dispersion process, the characteristic quantity of which is the dispersion coefficient (D) having the same dimension as a diffusion coefficient; if the dispersion is simulated by ID-model, it is called axial dispersion coefficient. As a criterion of dispersion, the dimcnsionlcss Pcclet number {Pe) which equals Pe = u.L/D (where u is the linear flowratc in the pores, L is the height of the bed and D is the dispersion coefficient) is often used. It holds, the greater Pe, the smaller dispersion.

To determine the dispersion coefficient, the so called stimulus-response method can be used [I]. It rests on the following procedure: through the column with soil or sediment bed flows the liquid phase under given flowratc and in time t=0 the trace component is injected into the stream of liquid phase. This "stimulus" is in the form of step input signal or impulse input signal, in both cases it is considered as a flow having plug form. In the given time the samples of liquid phase are taken away from the column effluent and the concentration of trace component is determined. The value of dispersion coefficient can be obtained from empirical data in different ways [1]. In this study, where the step input signal was used, the calculation of D was realized by means of the following relations [2]:

F ecjibCo i ( 1 _ e r / w ) (1)

Л - 2 ( D ] (f/m)'/» W where means

C(l) ... concentration in column effluent in time t, Co . . . starting concentration in column, Cm ... concentration in the injected solution, t . . . time, tm ... mean holding time of the trace component in column bed, и ... linear flowrate of the liquid phase in pores, L ... height of the soil or sediment bed, D ... dispersion coefficient.

731


Experimental procedures. The apparatus consists of a column with internal diameter 9xl0~3m, laboratory peristaltic pump and laboratory sampler. The solution 0.1 M LÍNO3 was injected into the stream of water and NOJ ion was used as a tracer. The following parameters were changed: the height of sediment bed (from 0.042 to 0.10 m), the flowratc of water in pores (from 0.22xl0"4 to 1.22xl0~*m.s~'), the mean size of sediment granules (0.054xl0~3m - 0.0815xl0~3m - 0.15xl0~3rn). The sample of sediment was taken from uranium mill tailings (near Dolní Rozinka, about 50 km north-west from Brno).

Results. On the basis of evaluation of empirical data the different values of dispersion coefficient reflecting the influence of the parameters studied were obtained. In order to quantify these dependencies the dimensional and nonlinear regression analyses were used and the following equation was derived (regression coeflicient=0.95):

D = -5.624 (A)-0.389 ( ^ 1 . 6 9 2 ( 3 ) Up 71

where means L . . . height of sediment bed, dp ... mean size of sediment granules, и ... linear water flowrate through pores of given bed, d . . . internal diameter of column (the diameter of the bed), s ... density of water, n .. . viscosity of water.

References: [1] LEVENSPIEL, 0. : Chemical Reaction Engeneering. Wiley, New York 1962. [2] SKRKAL, J.: Stanovení koeficientu axiální disperze. Diplomová práce, ČVUT, Fakulta

jaderná a fyzikálně inženýrská, katedra jaderné chemie, Praha 1994.

This research has been conducted at the Department of Nuclear Chemistry as part of the research project "Modelling of Contaminants and Radionuclides Migration in Soils -Development of multicompont Models of Fundamental Processes and 2-D Models of Sorp-lion/Desorption Dynamics" and has been supported by CTU grant No. 48215.

732


MULTICOMPONENT EQUILIBRIUM SORPTION MODELS

K. Štamberg, P. Beneš, D. Vopálka, K. Chalupská

CTU, Fac. of Nucl. Sci. & Phys. Eng., Dcpt. of Nuclear Chemistry Břehová 7, 115 19 Praha 1

Key words: equilibrium models, soil, sediment, aqueous solution, Zn, Cu, Ni, sorption, multicomponent models

Theory. Two types of equilibrium models, which were called additive and interaction models, can be used in the description of multicomponent sorption systems.

In the case of additive models, only one equilibrium equation is used for one component, any reciprocal interaction between individual components is not considered. It deals with equations, like Kd-, Langmuir- and Freundlich-equation. These types of models are relatively simple. However, because of the missing interactions their application is possible only under special conditions.

The interaction models describe the given system by means of one equilibrium equation. From the physical-chemical point of view, there are two types of interaction models which can be used: (i) the models of multicomponent adsorption and (ii) thermodynamical chemical equilibrium models. The first one, like the multicomponent Langmuir equation, is based on the assumption that the total sorption capacity is constant and the sorption of each component is described by reversible addition reaction Aj + R = RAj, the equilibrium constant of which К J = RAjf(Aj.R) (where Aj is the concentration of J-th component in solution, and R is concentration of active sites in solid phase). The second, based on the equality of chemical potentials of mentioned components in both phases, describes the given chemical reaction, like addition-, substitution- (including ion-exchange-), complex-, hydrolytic- and precipitate-reaction. The equilibrium constant of each of these reactions is the characteristic quantity of the studied system.

Experimental procedures. The equilibrium sorption isotherms for Zn, Cu and Ni were determined for the sediment sample from uranium mill tailings (near Dolní RoLinka, about 50 km north-west from Brno) by means of a batch method [1] using the aqueous solution with the following composition:

2.5xlO"5M ZnS04 + SxlO"6M CuSO., + 8.5xl0-6M NiN03 + 1.5xl0"2M NaCI + 5xlfr2 Na2S04 + lxl0~2M NaHC03 + 5xl0"4M (NH4)S04. The relation V/m, where V is a volume of the solution and m is a mass of the sediment sample, was changed from 10 to 500 ml/g. The concentration of Zn, Cu and Ni in aqueous phase was determined by AAS and the content in the solid phase was calculated.

Results. In order to find the best multicomponent equilibrium sorption model the empirical data were fitted with (i) 3-component Langmuir equation, and (ii) three thermodynamical equations differing in the type of chemical reaction mentioned.

In the case of the Langmuir equation the sorption capacity for Zn (Ql) is given by the relation: Q\ = Cl.Kl.Qmax/(l + Cl.A'l + C2.K2 + СЗ.Л'З), where Ql, Q2, Q3 are the sorption capacities for Zn, Cu, Ni respectively, Cl, C2, C3 are the concentrations of Zn, Cu, Ni in aqueous solution respectively, A'l, A'2, A'3 are the equilibrium constants for Zn,

733


Cu, Ni respectively and Qmax is the total sorption capacity. The values of /v'l, A'2, Л'З and Qmax were obtained by the above-mentioned fitting of empirical data. If the concentration quantities arc in mmol/dm3 (C) and mmol/kg (Q), the values obtained are: A'l = 16.9 (<r = 0.837), A'2 = 27.7 (a = 1.39), Л'З = 5.11 {a = 0.271) and QmnI = 62.1 [a = 2.33) (<r is the standard deviation).

The basic chemical reaction, which was used in the case of the thermodynamical model, can be schematically noted as:

sl.Cl + s2.C2 + s3.C3 + sA.QA = sl.Ql + s2.Q2 + ,s3,C?3 + sA.CA

where si, .?2, s3 are the stcchiomctric coefficients of Zn, Cu, Ni respectively and s4, CA, QA hold for the exchanged ion the valency of which equals one. The values of stcchiometric coefficients were calculated on the basis of balancing the empirical data and the following values were obtained: s\ = 1.00, s2 = 0.2325, s3 = 0.2060, sA = 2.877. On the assumption that the activities were equal to molar concentrations, the equations of the thermodynamical equilibrium constants and consequently of the sorption isotherms for addition-, substitution-and a set of monomolecular reactions were derived.

For addition reaction: Q\ = К1У']) (<72/Q2)<í2/»U (CS/QW"3'» Q4<">/"> Cl

For substitution reaction: Q\ = КЩ31) (C2/(Q2)<í2/"> (С3/С?3)^л,> (Q'l/C'l)^^ Cl

For the set of monomolecular reactions: Q\ = A'<i/5l> (C2/Q2)<°V'V ((73/<?3)<j3/'1> 6'1

The values of equilibrium constants A'„,/, A'JU4, I\mr and the starting concentrations of the exchanged ion in the sediment sample (Q40), in the case of addition and substitution reaction, were determined by fitting the empirical data. The following results applying to concentrations in mmol/dm3 (C) and in mmol/kg (Q) were obtained:

Kad = 3.39xl0"3 (<T = 6.69xl0"s) , (Q40)OI, = 223 (<r = 1.34) , K,ub = 2.24xl0-4 (о- = 2.38Х10"6) , (Q40)aub = 55.7 {a = 8.79xl0"2) , Kmr = 1.22x10'* (a = 323) .

On the basis of the standard deviations of the equilibrium constant values, any equation used in this study can be considered as useful and applicable. However, the reciprocal calculation of the sorption isotherms using nonlinear regression shows that the 3-componcnt Langmuir equation gives the best agreement of calculated and empirically obtained data.

References: [1] STAMBERG, K. - VOPÁLKA, D. - CHALUPSKÁ, K.: Study of Pb2+ Sorption on

Forest Soil. WORKSHOP 93 - Environmental Engineering, Czech Technical University,, Prague 1993, pp. 141-142

This research has been conducted at the Department of Nuclear Chemistry as part of the research project "Modelling of Contaminants and Radionuclides Migration in Soils -Development of mullicompont Models of Fundamental Processes and 2-D Models of Sorption/Desorption Dynamics" and has been supported by C'TU grant No. Jt82l5.

734


DIFFUSION AND SORPTION OF TRACE ELEMENTS AND RADIONUCLIDES

IN SOILS A. Gosnian, L. Peťková, L. Šustrová, N. Kosatková

CTU, Fac. of Nucl. Sci. & Phys. Eng., Dcpt. of Nuclear Chemistry Břehová 7, 115 19 Praha l

Key words: trace elements, radionuclides, diffusion, sorption, moisture, soils

In the previous research [1,2] we checked the developed capillary modification of the thin layer method for the study of the diffusion of trace elements and radionuclides in soils.

The method is based on diffusion from an infinitely (very) thin labelled layer through a thick layer of moist soil in a glass capillary and sectioning very thin layers of the soil after diffusion.

The value of effective diffusion coefficient Dc/ for Fick's 2nd law dc/dt=Dcj (д2с/дх2) is determined by a=a<>exp(—.-е2/4Д.//)/(я-Дг//)1/2, where ao and a - initial (in infinite - very thin layer) specific activity and specific activity of the layer removed at a distance a; from the origin of coordinates, / - total diffusion time. According to Prochorov (see in ref.1,2) De/ = D0 s/(l+Kd/i«), where s = S/So (S and S0 - cross sections of the liquid phase in the soil and of the capillary, respectively), Do - diffusion coefficient in infinite or reasonably diluted solution in the absence of adsorbing medium, w - moisture, K</ - distribution coefficient. The method shortened the necessary diffusion time to several days. Some results of the diffusion of 85Sr and 137Cs presented in the above papers:

1) decrease of De/ and K,/ with decreasing soil moisture; 2) s = f(w) is analogous to tortuosity - it decreases with decreasing w, i.e. it is

connected with the geometric factor (at certain conditions s = kw is valid); 3) for the same soil type but for different soil particles dimensions the different De/(137Cs) values were determined - for sample with particles dimensions 1.7 times

smaller than for the second sample the De/ is by one order smaller which is evidently due to greater sorption capacity and tortuosity change in the first sample.

In this communication we present the study of the diffusion in other soil types (No.l — NoA) of similar composition and pH, which differ in the density (it increases in the No.l — NoA sequence being for No.l 1.422 times smaller than for NoA). Within the framework of minimum and maximum ^ values (V-volume of water for wetting of soil amount m) we again found an increase of Kj and De/ values both for 85Sr and 137Cs. With regard to similar soil types it was interesting and important to know how the mean parameters Dc/ and Kj for corresponding mean maximum and minimum (j£) values (the results can be useful for the diffusion prediction in similar soil types) differ, For mean maximum and minimum (—) values it was found the ratio oi~Dej,max / A:/,mm= 5.286xl0~7 cm^s"1/l-175xl0"7cm2s~1 = 4.5 in the case of 8SSr, and in the case of ,37Cs it follows Д./ , т а г / Def<min = 4.918xl0-8/0.936xl0-8

= 5.25.

735


The corresponding ratios for (—) and /v'j values are:

(£)««• / (£)«*.= 0.279/0.168 = 1.66 and (K~d)max ЦЩ,„ы = 9.146/7.53 = 1.21 in the case of 85Sr; in the case of ,37Cs is valid (%)ma* /(£)„,,•„ = 0.278/0.144 = 1.93 and (Щ)т„/(1Ъ)ы« = 337.5/322.7 = 1.04.

Further it is important a) to compare the corresponding calculated Dej,m»x a n t ' ^c/,mm values which for 85Sr give the_value 1.95 and for ,;,7Cs 2.94; b) to compare experimental values of Ое/,тпх (85Sr) and De/,max(137Cs) which ratio is 10.75, and De/,mm(85Sr) and £)e/,m,-n(,37Cs) giving the ratio 12.55 (for calculated values it is valid ratio 15.27 and 23.1, correspondingly); ratio (A7)mai(

137Cs) /(A'j)m0X(8SSr)=36.9 and for (Л',()т(п equals 42.88. For the next soil type (No.b) which has similar composition as types NoA — NoA and

density 2.576 it was found that with j£ increasing (0.07 - 0.18 - 0.30) De/(85Sr) increases

(0.447xl0-7 - 0.677xl0~7 -0.547.xl0-(?); for similar change of — (wcttitig the soil with 0.02 moll"1 СаСЬ) in the range 0.09 -

0.195 - 0.30 the De/(85Sr) values are markedly greater (UlGxlO -7 - 6.25xI0-7 - 1.176xl0_e).

Conclusions and results: a) all values of De/ are markedly smaller than limiting Ncmst D0 values (D0(Sr2+) =

7.9xl0-ecm2s-1 and D0(Cs+) = 2.05xlO-scmV1). From this and from comparison Do(Sr2+/Do(Cs+) = 0.3S5 with corresponding ratio of

De/ values wc observe the great influence of the sorption and tortuosity effects in soils; b) from comparison of Kj and De/ values in the case of No.b (wetting with CaCli

solution) it follows that the greater increase of De/ is given by opposite change of Kj with (£ ) v a | i l e s ;

c) from the results follows the possibility of prediction of the diffusion transport in soils.

References:

[1] GOSMAN, A. - BLAŽÍCEK, J.: The Effect of Liquid Phase Distribution, Sorption and Soil Particles Dimensions on Diffusion of Trace Elements and Radionuclides in Soils Workshop 94-Environmental Engineering, CTU Prague, 1994, 17-18

[2] GOSMAN, A. - BLAŽÍCEK, J.: Study of the Diffusion of Trace Elements and Radionuclides in Soils. Capillary Modification of the Thin Layer Method. Diffusion of 137Cs. J. Radioanal. Nucl. Chem., Articles, VoI.JS2, No.2, (1994), 179-191

This research has been conducted at the Department of Nuclear Chemistry as a part of the research project "Modelling of contaminants and radionuclides migration in soils-development of multicomponcnt models of fundamental processes and 2D-models of sorp-tion/desorption dynamics" and has been supported by CTU grant No. 48215.

736


INTERACTION OF TRACE ELEMENTS WITH HUMIC SUBSTANCES

AND ITS EFFECT ON THE ADSORPTION ON CLAYS

K. Kratzer, P. Beneš, J. Mizera, H. Kyzeková

CTU, Fac. of Nucl. Sci. & Phys. Eng., Dept. of Nuclear Chemistry Břehová 7, 115 19 Praha l

Key words: humic substances, trace elements, association, adsorption, clays, cadmium, zinc

Adsorption reactions on solid surfaces in groundwater zones exert an important control on metal ion and radionuclide aqueous concentrations and their migration velocities through such systems [1]. Humic substances sorb to mineral surfaces thereby changing the surface properties [2]. Surface bound humic substances can increase the adsorption of certain metal cations on single mineral solids by contributing additional, potentially high affinity, com-plexing sites. On the other hand, formation of nonsorbing aqueous complexes can decrease metal ion sorption. Generally, humic substances have been shown to have variable and contrasting effects on metal binding, depending on the complexation properties of the humic substance, the distribution of the humate between the solution and solid, and the variation of both of these with respect to pH and ionic strength [3]. In this communication two coal hurnates industrially produced in the Czech Republic (B - producer HD Bílina and S -Sokohum, producer HD Březová) were investigated with regard to their binding properties towards heavy metals and their effect on the adsorption of heavy metals by clay.

In collaboration with the Institute of Geotechnics, CAS, the humates were characterized chemically using a coal analysis method, AAS and UV-VIS spectrophotometry. The results obtained were compared with those for the standard humate (Aldrich Chemical Company). No significant differences were found.

The applicability of UV spectrophotometry for the determination of the concentration of humatcs under study in aqueous solution was verified. It has been found that the concentration can be directly measured in range 0.2 - 150 mg humate/1.

The ultrafiltration technique was used for fractionation of the humates according to the molecular weights. The light absorption and DOC were measured in each fraction. The data obtained indicated that the main part of humate В is represented by the fraction with molecular weight 3000 - 10000 (more than 40%), whereas in humate S two fractions with molecular weight 50000 - 100000 and more than 100000 dominate (each more than 30%).

The precipitation of humic acid as a function of the equilibrium pH value was studied. A centrifugation was used for separating solid and liquid phases and UV-spectrophotometry served as an analytical method. It has been found thai che distribution of humate В can be described by equation

/nnr , 0.25 *10""-7 2.7*102"H-8 . с = с о . ( 0 . 0 5 + 1 + 5 ^ 1 0 р Н _ 7 + 1 + 3 ^ 1 0 2 р , / _ 8 ) , (1)

737


where с and Co arc the equilibrium snd initial concentration of humalc in aqueous phase, respectively. An analogous equation has been found for description of distribution of hum ate 5

/ n n . 0.15*10""-° 1.6 * Ш2""-7 , с = со, (0.05+ 1 + 1 0 p „_ 6 + 1 + 2 , 1 о г р ^ 7 ) - (2)

Batch experiments were used for investigation of the distribution of humate В between cypris clay and aqueous phase (/ = 0.1). The results obtained have shown that in systems containing a sufficient abundance of clay the dependence of the distribution coefficient A'j on pH can be described as:

log Iú = -0.43 pH + 4.81 . (3)

In systems with a similar content of clay and humate the course of the dependence is more complicated.

Zinc was chosen as a metal representing an "average" chemical behaviour of toxic metals. The sorption of radioactive 05Zn on cypris clay was studied in batch experiments. It has been found that the distribution coefficient Kd can be used for describing the distribution in conditions under study. The dependence of the distribution coefficient A'j on pH can be described by equation

\ogh'd = 0.75PH-2 . (4)

The analysis of zinc sorption on cypris clay in the presence of variable concentrations of humates Вот S confirmed that the humates can increase or suppress the sorption, depending on the concentration, pll value and clay to solution ratio.

In order to better elucidate the effect of Immate a study was begun of the interaction of heavy metals with the humates in aqueous solutions. Cadmium labelled with 109Cd, ultrafiltration and dialysis were used for this purpose. It has been found that humates В and S form associates with cadmium which are retained by the dialysis membrane and ultrafilters with molecular weight cut-off value of 1000-10000 D. The association depends on the pll value and concentration of humate. Further experiments are planned for quantitative characterization of the association, and of the elcctrophoretic mobility of the associates.

References: [1] KENT, D. B. et al.: Surface complexation modeling of radionuclide adsorption in sub

surface environments. U.S. Nucl. Reg. Comm. NUREG Rept. CR-4897, 1988. [2] LIAG ,L. - MORGAN, J. J.: Aquatic Sci., 1990, 52, pp. 32-55. [3] ZACHARA, J. M. - RESCH, С. Т. - SMITH, S. C : Geochim. Cosmochim. Acta,

1994, 58, pp. 553-5C6.

This research has been conducted at the Department of Nuclear Chemistry as part of the research project "Interaction of trace elements with humic substances" and has been supported by CTU grant No. 48208.

738


MEASURING THE MATERIAL PARAMETERS OF RADIOACTIVELY

CONTAMINATED WATER IN THE ROŽNÁ WASTE DISPOSAL SITE

J. Toman, V. Havlík*, O. Hrstka*, R. Černý

CTU, Faculty of Civil Engineering, Department of Physics Thákurova 7, 166 29 Prague G

*CTU, Faculty of Civil Engineering, Department of Hydraulics and Hydrology Th/ikurova 7, 166 29 Prague 6

Key words: pollutants, waste, material properties, measuring

One of the possible ways to cope with liquid waste products containing pollutants is to put them into waste disposal sites such as deep empty pits. The environmental safety of this approach can be evaluated for example using a mathematical model to calculate temperature-, concentration-, velocity- and pressure fields in the fluid. The reliability of this type of calculation primarily depends on the accuracy of the input parameters of the model, the most important of them being the material properties of the fluid.

In the classical continuum theory, the most frequently used material parameters in the balance equations are thermal conductivity, specific heat, density, viscosity, thermal expansion coefficient and diffusion coefficient. All these material properties depend on the actual state of the fluid and/or external conditions. In the case of water, the temperature and the admixture concentration are among the most important factors.

In this paper, we describe measured material parameters of radioactively contaminated water in the waste disposal site Rožná, whose values of admixture concentrations (see [1], for a compilation of the data) are relatively high, ~ 20-30 g/1.

Measurement of density of the contaminated water was carried out by the pyenometric method (sec, e.g., [2]) taking into account its dependence on temperature, using a climatizing chamber and determining the mass of the pyenometer with water after tempering. The measured densities are shown in Table 1.

The volume thermal expansion coefficient /3 was calculated from the definition formula, pr = Л>(1 — /?ДТ), «sing the p(T) function. The results are summarized in Table 1.

Thermal conductivity was determined by the commercial apparatus Shotherm QTM working on the basis of the hot wire method. Since the apparatus has been designed to perform the measurements on the solid materials only, we had to do some adjustments. The measuring probe was covered by a thin foil and put on plastic supports placed within the dish with water. The mean value of the thermal conductivity at 25 "C, calculated from 10 measurements, was A = 0.6 VV/mK. It should be noted that the variance of the measured values was relatively high, the standard deviation being á.\ = 0 . 1 W/mK. The probable cause of this might have been insufficient contact of the measured sample through the foil with the measuring probe.

Viscosity was measured by the Stokes method (see [2]) using a 2 m long tube. Since we could not achieve a uniform motion of falling spheres in the tube, we used a comparative

739,


Table 1 Density and volume thermal expansion coefficient of the contaminated water as a function of temperature

T(°C) 11.0 16.5 22.3 27.5 31.3 59.1

p(kg/m3) 1029.204 1027.803 1025.984 1024.227 1022.989 1012.740

года-1) -2.47 2.76 2.93 2.97 3.32

treatment, with distilled water as the reference fluid. The mean value of dynamic viscosity at 25 °C was determined as n = 9.Ы0 - 4 kg/ms.

We compared our results with the reference data for distilled water from [3]. The density of our contaminated water was higher by 27-29 kg/m3, the volume thermal expansion coefficient was for T < 27°C higher by ~ 10-20 %, for T <> 7°C lower by ~ 10-20 %, the thermal conductivity was lower by 2 %, and the dynamic viscosity higher by 6 % in comparison with the distilled water values.

The primary objective of the measurements has been to determine experimentally the material parameters of radioactively contaminated water from the waste disposal site in Rožná. The measured values of the material parameters will be used for numerical calculations of natural convection.

References: [1] HAVLÍK, V. É- ČERNÝ, R. - TOMAN. J.: Disposal of Surplus of Polluted Water from

Waste Disposal Site into the Deep Pits of Rožná, Research Project No. 105 793, CTU Prague, 1993, (in Czech).

[2] HORÁK, Z. - KRUPKA, F. - ŠINDELÁŘ, V.: Technical Physics, SNTL, Prague 1960, in Czech.

[3] INCROPERA, F. P. - DE WITT, D. P.: Fundamentals of Heat and Mass Transfer, John Wiley and Sons, New York 1990.

This research has been conducted at the Department of Hydraulics and Hydrology and the Department of Physics of the Faculty of Civil Engineering and has been supported by the Grant Agency of the Czech Republic, under grant No 103/93/0395.

740


STUDY OF THE SHORT TERM FLUCTUATUION OF WATER

CONSUMPTION

L. Macek, P . Zykan

CTU, Fac. of Civil Eng., Dept. of Sanitary Engineering Thákurova 7, 166 29 Pwdia 6

Key words: water consumption, short-term demands

This article deals with the monitoring and evaluating of short term changes of water consumption. Two main drinking water distribution areas were studied. In Mlada Boleslav (aprox. 50 000 inhabitants) the water use of two main pressure zones were monitored at 1 minute interval. In Kladno the results of the monitoring 5 selected closed areas of water distribution were studied. From the time series of water consumption the plots of probability for water use were constructed. A scheme was then proposed to improve the data for the design of a water distribution system.

The main reason for carrying out this study were

(a) to get the real pattern of water consumption in a very short interval (b) to find out if there were some important changes of water use in this short interval (c) to analyse the monitored data to construct probability plots of water use

Water use in 1 minute interval Wedneday01/0im

s

5 IOO

JIM.'] п*Л, X*4ř/

к J

MOO oaoo 10» 1200 нов ton laoo woo n n oooo 0200 0400 OIOO 0000 1100 1100 1300 1100 U I» 3100 ПО0 01 0» 0100 OIK

Time (h)

Fig. 1 Monitored changes of water use, January 1st, 1992, Mladá Boleslav

One of the results of this study is demonstrated in Fig. 1 where the plot represents changes of water consumption on January, 1st, 1992 at Mlada Boleslav. There the beginning and end of the film "Vesnicko ma středisková" by Jiri Menzel can be identified. Two periods of a sudden increase in water use can be observed. The measured maximum was at least

741


2.5 time higher than the average water use, with the increase of water consumption 100 1/s in a period of 5 minutes.

The data of water consumption was analysed in several ways. Some of the results of data analyses can be seen in Fig. 2. From the probability plot of water use vs. interval of water use it can be deduced, that for the design of a water distribution system another system of water demands fluctuation can be used. In small areas of water use with less importance it is possible to use the coefficient of imbalance with higher probability. The important parts of water distribution systems such as the town centres and residential areas with large blocks of flats should be designed on the basis of water use of lower probability.

Probability of water use Propast, 10/6 - 8/7/92

Si "a

Time (min)

Fig. 2: Probability of water use: water use vs. time intervals

References: [1] SIVVON, Z. - STANISLAWSKI, J.: Ueber die stochaslischc Wasserbcdarfspmgnose in

Stadlcn als Basis zur Steuerung und Konlrollc von Wasserversorgungssyslemcn. GWF Wasscr, Abwasscr, 129, 113, 19SS

[2] MACEK, L. - ZYKAN, P. - SEDLAČEK, J. - NOVOTNÝ, Т.: Nerovnoměrnost odběry vody. SOVA К, No. 7-8, p.33-34,209,1994.

This research has been conducted al the Department of Sanitary Engineering as part of the research project "Study of short-term fluctuation of water consumption" and has been supported by the Faculty of Civil Engineering's grant No.2096.

742


HYDRODYNAMICS AND STABILITY IN ENVIRONMENTALLY

ACCEPTABLE CHANNELS K. Mareš, I. Bémová, I. Marešová, J . Vodsloň

CTU, Fac. of Civil Eng., Dept. of Hydraulics & Hydrology Thákurova 7, 166 29 Praha 6

Key words: hydrodynamics, stability, river re-naturalization, laboratory works, field measurements, data base application

Within the framework of the Elbe river Project and within the prepared "Action Elbe River" Programme ecological studies of rivers are being carried out. These studies represent an international cpoperation. However, in comparing the results of similar studies of the Elbe river and its tributaries in Germany, with the results of our studies, a polemic of convenience and labour consumption in the methodological processes lias arisen between both cooperating partners. Both partners are enforcing their own system of passing ecological judgement. The Czech side intend to utilize the software LABE (Elbe).

The software LA BE is an open database system with an analytical tool for evaluating the ecomorphological quality of both a river and its close vicinity. LABE evaluates using a method of multicriterial analysis. However, a crucial factor in its implementation is the objective setting up of the weighting coefficients. Results of a sensitivity analysis carried out have shown that the overall results are strongly influenced by the setting up of the weighting coefficients. Therefore, a new sensitivity analysis for a wider range of data was suggested.

Creating the natural conditions in a river channel in the bed and in the bank slope material represents an important choice. From the viewpoint of the re-naturalizations of rivers, it is desirable for this material to be a natural - original one. Because of the diversification of a river channel during re-naturalization, such actions tend to lead to a decrease in the channel capacity. At the same time, the natural material stands in an apparent contradiction to the requirement of creating a stable channel, and using a channel where the erosion and silting processes can be predicted.

All these reasons led to the decision to create the software STABILITA. The STABILITA software has been built to solve the problems of bed material stability, or to predict the depth of possible erosion. There are 15 various methods implemented in this software. In our research programme, after final verification questions regarding the appropriate method for selection of a given type of river (alluvial rivers, torrents, mountain rivers) will be answered.

In 1993 field measurements were carried out on selected river reaches of the Chomutovka river and the Flájský brook. While these measurements were being taken, data about the beds basic geometry, morphology and sediments were collected. This data has been evaluated this year. Based on the evaluated data, detailed measurements have been taken of the velocity fields at three river reaches (using 10 cross sections) over this autumn. The discharges can be controlled by the Flájský reservoir. However, the measurements have

743


shown that in order to safeguard the people measuring in the channel, the discharge has been limited to 1,5 m 3 s - 1 .

The flow resistance of the artificially trained mountain brook Bouřlivec was one further part of our investigation. Large natural stones have been densely distributed into the bottom concrete of the straight rectangular channel. As the roughness elements arc of the same order of magnitude as the depth of flow I he roughness is considered to be large scale. A compound thin plate weir was installed in the rcacli of interest for discharge measurements. As there is no water reservoir in the Bouřlivec brook catchment no possibility exists to control discharges. Thus the aim of the Bouřlivec project was to establish the feasibility of using a family of physical models in the faculty lab (scale 1:8 and 1:20) and reality (scale 1:1) to evaluate the discharge coefficient of the compound thin plate weir installed in the mountain brook Bouřlivec under the irregular approach channel conditions - viscosity and surface tension influence have been found, defining the correlation factor К in the range Re02We06 < 900, and designing also the roughness coefficient of this brook respectively. Two types of equations for determining the flow resistance for this particular case have been used in the analysis. The first one developed by Bathurst (equating roughness to the Darcy-Weisbach coefficient), and the second one put forward by Jarrett (expressing roughness in terms of Manning's coefficient). The Jarrett equation has been found to give good agreement between both models and reality as well. However, insufficient equivalent discharges in the models and in reality prevented the making of firm conclusions with regards to the limits of the equations validity.

Both problems solved on the Bouřlivec brook have been compiled in two M.Eng Technical Submissions - Stevenson, K. and Harvey, A.S.R - both from Hcrriot-VVatt University, Edinburg, UK, 1994.

In accordance with our project, the first part of our experimental structures on the Ploučnice river near the village of Žízníkov was finished in autumn 1994. This experimental river reach was set up to focus on the elements and constructions most frequently used in the re-naturalization of rivers. Because of an extremely dry and warm year and because of inadequate care of the structural cnterprizc from the point of view of vegetational bank protection, some vegetational structures did not strike roots. Those structures will be repaired at the beginning of the coming vegetational period. For this reason most of the field measurements on the Ploučnice river had to be postponed to 1995.

A data base application has been created for the data which has been and will be collected from field measurements. The collected data should be validated and pre-processed using the software application in order to maintain the data describing the measured river reaches. In order to carry out extensive calculations of the two dimensional flow in a meandering channel, tests of the transfer of the software FLU VIUS from MS DOS to UNIX system have been carried out.

References: [1] MAREŠOVÁ, I.: Evaluating Flow Resistance using Height of Roughness Protrusions

Proceedings of the A S С E Conference Hydraulic Engineering 94, Vol. 1, Buffalo, pp. 712-716

This research lias been conducted at the Department of Hydraulics and Hydrology, Faculty of Civil Engincerig as part of the research project "Revitalization of Trained Rivers" and has been supported by CTU grant No. 1 8075.

744

WORKSHOP <J5 ENVIRONMENT & ITS CREATION

IMPROVEMENT OF WATER QUALITY IN RIVERS BY AERATION

AT HYDRAULIC STRUCTURES

P. Gabriel, J. Dolccck

CTU, Fac, of Civil Eng., Dcpt, of llydrotechnics Thákurova 7, ICG 29 Praha 6

Key words: water quality, oxygen balance, aeration by overfall

The present inconvenient condition of water quality in our rivers is necessary to be improved above all through elimination, or at least through reduction of the main sources of both local and larger - area pollution, Л further means of improving water quality is through stimulation of the self • purification processes by the addition of oxygen to the water, especially in places and periods where and when oxygen deficiency occurs. To implement this, the existing hydraulic structures on the rivers may advantageously used.

The physical substance of the aeration process has already been principally cleared up in the past, but the problem of effective aeration at hydraulic structures has remained unsolved both theoretically as well as practically. From this confusion arose as to the choice of the most effective way of aeration at these structures. Besides that the impact of the aeration effect on the downstream river or the weir reservoir was not sufficiently investigated.

The main aims of the grant consisted in: - a theoretical and experimental solution of aeration efTectivity at overfall and its com

parison with aeration at other flow transition phenomena, - quantification of the aeration effects at hydraulic structures and their energetical and

economical evaluation , - investigation of the impact of aeration effect on the downstream river and the weir

reservoir, especially the aeration effect at hydraulic structures eliminating, or at least reducing the oxygen bend along the rivers and weir reservoirs.

The concentration of dissolved oxygen in water together with the water temperature belong to the basic indicators of the admissible pollution level of surface waters. According to valid rules the saturation of water with dissolved oxygen must not fall below 50%, i.e. roughly below 5.0 mg. 1"' at temperatures not higher than 26 ° С

In the experimental part of the research three large groups of measurements were car-riedout in climatic different periods (July - August, September - October). The measurements were carried out on the navigable sector of the Labe between Chvaletice and Strekov during periods of low and extremely low discharges and at relatively, respective absolutely high water and air temperatures.

On the chosen hydraulic structures (Strekov, Brandýs n.L., Klavary and Smiřice) the aeration effect at overfall was compared by different manipulations on the weirs with the oxygen situation during the operation of power plants. These measurements were completed by a long time observation of the oxygen situation over and under the weir at Klavary during a period of extremely low discharges and extremely high water and air temperatures.

745


At the most effective mode of aeration by overfall over weir gates the impact of the improved oxygen balance was measured along the downstream weir reservoir (under hydraulic structures at Brandýs n.L. and Smiřice), respectively along the downstream river under Strekov.

To obtain a quantitative idea about the development of the oxygen situation and the related temperature profile on the continuous cascade of low - head hydraulic structures measurements of the oxygen concentration and water temperature were carried out along the whole navigable sector of the Labe, including the canalised sector Strekov - Hřensko.

The carried out experiments proved the positive influence of hydraulic structures on the oxygen regime in the weir reservoirs. The greater the part of the total discharge conveyed over the weir by overfall, the greater this effect.

During the critical periods of low discharges and higher water temperatures the largest effects were reached with the aeration by overfall over all the weir gates . By this intervention it is possible to positively influence also the zone of oxygen bend and to reach a sufficient concentration of dissolved oxygen along the whole length of the weir reservoirs.

The results of the aeration measurements by overfall were compared with the theoretical results of both Novak and Nakasone. Comparative computations showed evidence of very good agreement between both the theoretical values and the measured values. Better results are obtained by Novak's method.

The energetically-economical evaluations showed, that aeration by overfall is more effective than aeration in the draft tubes of turbines, and this is true even when considering the cost of the partial losses in electricity production.

From the results of the realised research flowed out concrete proposals for modification of the manipulation on the hydraulic structures during the periods of oxygen deficiency. These proposals were passed over to the operator of the hydraulic structures and were immediately applied with positive effect. Their application in the future will contribute to the improvement of the general ecological situation on the river and in its immediate neighbourhood.

References: [1] NOVAK, P.: Improvements of water quality in rivers by aeration at hydraulic structures

Chapter 6 in M.Hino (editor): Water quality and its control - IAHR Hydraulic Stuctures Design Manual, A.A.Balkema, Rotterdam, 1994.

[2] GABRIEL, P. et al.: Project Labe, 1993.

This research has been conducted at the Department of Hydrotechnics as part of the research project "Improvement of Water Quality in Rivers by Aeration at Hydraulic Structures" and has been supported by CTU grant No. 18157.

746


STABILIZATION OF SOLID WASTES FROM THERMAL POWER STATION

BY CALCIUM CARBIDE LIME S. Modrý, J. Janota*

CTU, Klokncr Institute, Dcpt. of Concrete Technology Solinova 6, 166 OS Praha 6

*EGÚ Praha a.s., 190 11 Praha 9 - Běchovice

Key words: stabilization, waste products, bottom ash, pulverized flying ash, calcium carbide lime

One of the main problems connected with the combustion of brown coal in thermal power stations is minimization of the negative environmental impacts due to gaseous and solid wastes.

The problems of gaseous wastes will not be discussed here. However, attention will be paid to the solidification of particulate waste at landfills. During the combustion of coal basically two solid waste products are created — bottom ash (BA), slag resp. and pulverized flying ash (PFA). In the case of the CEZ thermal power station at Lcdvice the mixture of the above mentioned wastes is transported hydraulically from the place of combustion to the landfills. The surface layers of the landfills are dried due by the sun shining and the wind blowing. In the dry state, fine particles arc transported by wind into the atmosphere. As a consequence of it, it is there harmful contamination of the environment around the thermal power stations by dust.

The main goal of the research project described has been minimization of the particle contamination of the atmosphere due to dust from the surface layers of a landfull site through solidification with the aid of calcium carbide lime. Attention has also been paid to the assessment of leachates from stabilizates with calcium carbide lime.

The calcium carbide lime came from a acetylcn production from the company Techno-plyn, Ústí n. L. It is special sort of the hydratcd lime usually contaminated by coke and containing a higher quantity of water.

The mixture of solid wastes of BA and PFA came from the CEZ thermal power station at Lcdvice. PFA especially belongs to the category with a lower content of calcium. Such ash is not usually too active in pozzolana reactions with basic materials, e.g. cement, lime etc.

The action of wind was modelled by horizontal wind flow of the velocity 15 rn/s approx. (this is equal to grade 7 on the Beaufourt velocity scale).

It has been proved that the lowest dustiness had the stabilized waste with the highest contents of lime. The ratio of the dried weight of the carbide lime to BA and PFA in this mixture was equal to 1:4.85.

The dustiness of the surface layers increases with decrease in the content of lime in the mixture and decreases with the age of the specimen.

Analysis of the leachates from the mixtures mentioned above has proved that the leachates of mixtures with BA and PFA contain (in comparison with the plain specimens

747


without calcium carbide lime) naturally increased the value of pll, as well as the level of calcium, sulphates, barium and strontium.

From an ecological point of view these facts should be born in mind in practical applications.

This research has been conducted at the Klokner Institute, CTU and has not been supported by any grant.

748


STABILIZATION OF Cd WASTES A. Griinwald, E. Poupová*, L. Svoboda*

CTU, Fac. of Civil Eng., Dept. of Sanitary Engineering Thákurova 7, IGG 29 Praha 6

*CTU, Fac. of Civil Eng., Dcpt. of Building Materials Thákurova 7, 166 29 Praha 6

Key words: cadmium, leaching, solidification, wastes

Stabilization (solidification) is one of the most widely used techniques for the treatment and ultimate disposal of hazardous wastes which contains heavy metals. The aim of stabilization is firstly to assess the risk of infiltration of hazardous materials into ground and surface waters, soils and air and secondly to improve the manipulation of wastes and thirdly to utilize tilts waste in specific circumstances.

Cement-based stabilization processes have proven successful for many sludges generated by the precipitation of heavy metals. Chemical stabilization and physical encapsulation are the two primary controlling factors in reducing metal mobility in the stabilized waste forms. The excess calcium hydroxide produced by cement hydration maintains a highly alkaline environment in the waste form. Most of the metal ions, which arc capable of forming insoluble hydroxides in alkaline aqueous solution, tend to be chemically stabilized in the soluble form in cement paste matrix [1], [2].

This contribution describes the partial results of an experimental study of the stabilization of Cd in cement paste and in high-ash slurry. A new measuring instrument Eco-Tribo Polarograf was tested in order to use it for measurement. A method of standard addition was adapted for this purpose.

At first, cement-based waste samples were made in the laboratory by mixing SPC 325 (Pragocement) with a water solution of cadmium nitrate. The concentration of Cd(N03)2

was kept within the range from 0.15 mol/dm3 to 0.45 mol/dm3. The specimens had a cylindrical form with a diameter 25 mm and length approx. 50 mm. The weight of the freshly prepared specimen was about 50 g. The cadmium nitrate solution was also used for preparing samples from cement-fly ash slurry. The same cylindrical forms were used. Similar specimens were made from cement and sludge originating from a biological digestion pond contaminated by cadmium.

The extraction fluid was made by adding 5.7 cm3 HOAc to 500 cm3 of dcmineralized water, adding 64.3 cm3 of 1M NaOH and diluting it to a volume of 1 dm3. When correctly prepared the pH of this solution is 4.77 - 4.97.

A modified static leaching test procedure was used to evaluate cadmium leachability from solidified materials. The specimen was hung in plastic gauze and put into a tall-form beaker (600 cm3) with the leaching solution (volume of cylinder : vol. of leaching solution 1:10). A magnetic stirrer was used for continual mixing during leaching. Conductivity and pH were measured continuously during 24 hours, Cd in the end of the test (after 24 hours), while only for few specimens were measurements of Cd made (2 or 3 times during 24 hours). Some samples were also put into distilled water.

Typical results are shown in fig. 1 and fig. 2. Comparing the test using HOAc and distilled water we can see differences in the pH time dependency. This is due to the buffer capacity of HOAC + NaOH. Solidification of real industry sludge will be dificult because

749

WORKSHOP 95 ENVIRONMENT*! ITS CREATION

the workability of sludge-cement composites is very poor. All results have a preliminary character and the experiments will continue. Important experiences were obtained with the static leaching method and with a new measuring instrument (the eko-tribo polarograf).

, 6 0 0 . . . . ..„_..„. .

_ 5.00 - — - - ~~"r~~' •g 1 4 . 0 0 - . - -

| з . о о -"a — - -*оИ § 2.00 • ^ - TcnduCťVity

^ 1.00 • . _ . . . 0.00

O P 4 4 - < o o o o o > j * ř < D e o p < > ) ; 3 ;

Time (hour)

Fig. 1: Time dependency of pll and conductivity

25.000 20.000

f 15.000 3 10.000

5.000 0.000 1

О ГЧ 4f (О CO

Time (hour)

о гм Я

Fig. 2: Cd concentration in leachate

References: [1] MODRÝ, S.: Stabilization of toxic sludges with portland cement pp. 149-150. Work

shop 93 Nakladatelství ČVUT Praha, Praha 1993. [2] SHIVELY, W. ct al.: Leaching tests of heavy metals stabilized with Portland cement.

Journal WPCF, vol. 58, No. 3, 1986.

This research has been conducted al the Department of Sanitary Engineering and Department of Building Materials as part of the research project "Solidification of wastes" and has been supported by CTU grant No. 18158.

750


RECYCLING OF SOLID CHROME TANNED LEATHER WASTES

D. Janáčová

TU, Faculty of Technology, Dept. of Automatic Control TGM 275, 762 72 Zlín

Key words: mathematic modeling, tanning processes, enzymatic hydrolyse

Chrome tanned solid wastes produced by the leather processing industry are a relevant problem of the present-day tanning production. These wastes are mainly dumped and, during 40 years, the leashed residues containing trivalent chromium from the dumps endanger the environment. This means also the loss of chromium and that of a valuable organic protein which could be reused.

Trivalent chromium could be recovered from solid leather wastes using the process of enzymatic decomposition which gives a mixture of complex chromium salts and hydrolysed protein. In this way, it is possible to remove chromium from dangerous dumps and to reuse chromium in tanning baths used in the production of chrome tanned leathers.

As a byproduct thereof, protein waste is produced, the main component of which are peptide chains and this waste can be used as fodder, fertilizers. There will be explored other ways of reuse as well.

Tanning with chromium salts is the most common method of tanning due to the following three reasons:

- creating a strong bond between chromium and protein (collagen)

- production of leathers with required characteristics, thermal endurance and water resistance, excellent hygienic characteristics

- production of intermediate product with unique look, the so-called wet-blue which can be easily processed to final product in accordance with the given commercial requirements

Especially the first factor - the high stability of chrome tanned leather, i.e. its strong bond between chromium and collagen means a problem for further processing of leather wastes. It is difficult to break this bond. Tanning is an irreversible reaction. Leather processing wastes ( shavings, hide powder, cutting waste) are of little use and protein which is blocked by this bond could be a very valuable raw-material for further use.

The overall aim is to eliminate the problems how to reuse the tannery wastes and to

751

WORKSHOP 95 ENVIRONMENT Si ITS CREATION

pay the attention to a full recovery of all byproducts.

For achieving the above task, it has been necessary

- to determine the optimum conditions for decomposing solid chronic tanned wastes with regard to the recovery of chromium and protein

- to determine the type of solid leather processing wastes from which the recovery of chromium and protein is possible

- to determine a liquid waste in which the recovered chromium can bo introduced ( e.g. tanning bath)

- application of a method for complex determination of trivalent chromium

- definition of a chromium recycling process, in what forms it is being performed

- appreciation of the tanning ability of a liquor prepared from recycled chromium ami comparison of the properties of wet-blue tanned in a tanning liquor prepared in this way with a standard wet-blue

- find a useful outlet for the organic component of solid tanned waste.

References:

[1] KOLOMAZNÍK, К. - LANGMAIER, F.: Treatment of Chrome Tanned Leather Wastes. Research Scientific paper, No. ZC 93 - 55, Zlín, May 1993.

[2] TAYLOR, M. M. - D1EFENDORF, E. J.: Compendium of Advanced Topics on Leather Technology. XXIst Congrcs of the International Union of Leather Technologists and Chemists Societies, Barcelona, Spain, September, 1991.

This research has been conducted at the Department of Automatic Control as part of the research project "Recycling of Solid Leather Wastes" and has been supported by CTU (TU) grant No.D 8493.

752


ACOUSTIC PROPERTIES OF THE POLYMER

AND RUBBER WASTE ELEMENTS M. Vaňková, M. Doložílek, A. Ryndová,

H. Grycová, S. Vašut*

TU, Fac. of Mechanical Eng., Dept. of Physical Engineering Technická 2, 61G 69 Brno

*TU, Fac. of Technology Eng., Dept. of Technical Physics náměstí Т. G. Masaryka 2785, 762 72 Zlín

Key words: sound absorption, airborne sound insulation, polymer and rubber waste

Together with the increase consumption of polymer materials proportionally increase the abundance of polymer and rubber waste, which in many areas seriously endanger the ecological stability of the country. Only a little portion of this waste can be recuperated with the properties of original materials. To liquidate the polymers or rubber waste is a very difficult task to solve. Rubber waste can be liquidated by burning, by yard or free dumping or by crushing. Using the resulting crumb is limited. In our research we deal with the possibilities of using these waste, which considerably concern the shoemaking industry and rubber industry as well for the manufacturing of the means reducing noise and vibrations. (Plates with high airborne insulation index, with critical frequency outside the area of the excitation frequency , with low surface mass and high absorption factor). The limit level of noise and vibrations become lower by way of getting the laws and directions stricter, mainly abroad. The demands for reducing noise levels arc stressed by increasing the sound powers of machines, by the development of traffic and by the economic pressure to save material and to reduce the mass of constructions. Using the polymer and rubber waste to reduce noise and vibrations in the environment suits to be one of the ecological and economical advantage for their liquidation. According to the recommendation of the opposers and due to the results which were gained during the first part of the grant, there were solved the following problems in the second part of the period in the year 1994:

1) The frequency response of the absorption factor and acoustic impedance of the elements from the rubber and polymer waste.

2) The influence of treat pattern on the acoustic parameters of these elements.

Ad 1). The absorption factor and acoustic impedance were measured by the standing wave method according to the C'SN 730501 standard. The absorption factor of the measured elements do not increase the value of 20% for the frequency from 250 Hz to 630 Hz. The real component of acoustic impedance is about 100 rayl for the low frequencies and for 4000 Hz. For the other frequencies varies from 0 to 20 rayl.

Ad 2). The airborne sound insulation of the elements was measured in the reverberation chambers according to the CSN 730513 standard. The measurement has been done on plates with dimension 0.950 m x 0.950 m. For comparison of acoustic quantities some of the usual buildings materials of similar properties are also presented.

753

WORKSHOP

Element

59

57

5a

5c 14

6a

6c 6b

95

Structure

Recycled rubber waste 25 Recycled rubber waste 15 Styropor, butadien styren rubber waste light-headed _ /; _ PVC + crumb from cork Kopolymer ethylenvinylacetát _ n _ _ a _

h [mm]

1.5

1.5

0.3

1.0 -

1.0

2.0 1.0

d [mm]

IS

15

26

23 16

24

IS 14

ENVIRONMENT & ITS CREATION

m' [kgm-2]

24.7

20.5

9.3

8.23 7.50

5.0

3.S 2.9

Rw„ [dB] 39

35

33

31 31

30

23 24

RwP [dB] 38.5

35

29 30

—

22 22

h — thickness of tread pattern, d — thickness of elements, m' - surface mass, Rw„ resp. Rwp — index of airborne insulation, tread pattern to source resp. receiving chamber.

Tab. 1: Characteristic parameters of elements

Conclusion. The soundproof properties of the elements from the polymer and rubber waste arc very close to the properties of usual building materials with higher surface mass. The tested material can be used:

- for reducing of the noise radiated by machines (shields, barriers), - as the soundproof materials in building industry and traffic (building elements, noise

barriers), - for dumping of the vibrations (elastic fixing of the machines, production of antivibra-

tion shoes, gloves and floors). The influence of the treat patterns on the index of airborne insulation was not found (Tab. 1). Small influence on airborne insulation can be seen in frequency characteristics.

References: [1] VAŇKOVÁ, M. et al.: Výzkum a zavádění progresivních metod při měření a hodnocení

hluku ve stavební akustice Výzkumná zpráva grantového úkolu Č.34/93-E. VUT Brno 1993.

[2] VASUT, S. et al.: Polymery a kompozity s polymerát matricí pro snižování hluku a vibrací. Výzkumná zpráva grantu GR 0292, VUT Zlín 1992.

This research has been conducted at the Department of Physical Engineering, faculty of Mechanical Engineering TU of Brno as part of the research project "Research and Application of Progresive Methods for Measurement and Testing in Building Acoustic" and has been supported by TU grant No.l-99134E.

754


ASPECTS OF THE INDOOR ENVIRONMENT

J. Kočí, J. Jurajda

TU, Fac. of Civil Eng., Dept. of Building Design Poříčí 5, 639 00 Brno

Key words: indoor environment, school buildings

At the Civil Engineering Faculty of the Technical University of Brno and at the Institut for preventive medicine of the Medical Faculty of Masaryk University of Brno a study was carried out by project 'Formation on the condition of the indoor environment in the school buildings' on questions dealing with the creation of external and also internal conditions of the environments in the schools. This study was made from the complex point of view of the relationship between the buildings and the indoor environments inside the classrooms, including the subjective feelings of the pupils.

The quality of residential environment encompassing both the interiors and the direct environment of residential and civic buildings is seen to depend intrinsically upon the integral design of a variety of features comprising aspect of utility, operation, layout, material, design, aesthetics and economy. However, considering the whole scope of creation of such buildings, the assertion can be made that the subjectively pleasant ambience, the positive feelings of man in his residential environment, as well as the possible risks to his health due to pollution, tend to be neglected, and not only in this country.

There are a number of problems related to ensuring overall good atmosphere and liv-ability in residential and civic buildings. The causes appear to be diversified and of different categories. This leads to problems, in particular for the design and the best use of various parameters of the residential environment.

The recent period brought enough knowledge on various factors of residential environment. The complexity of this environment, however, requires the state of many features to be monitored at a time, many correlations of the phenomena and many interdependent influences to be ascertained, while considering the dynamics of the variations of the studied phenomena and their laws.

If concentrating upon measurable characteristics, i.e. especially the structural and material aspects, it can be asserted, as based upon theoretical considerations, that the character of residential environment and its standard of quality are basically afTected by:

1. external influences, combining various components and aspects of external environment burdened by a broad range of environmental problems. The decisive factor is seen to be the anthropogenous activity and the industrial and traffic density of the country, in additional to the climatic, meteorologie and gco-anomalous situation of the given site,

2. building structures and materials limiting the internal space. This has a twofold effect. On the one hand, various components and aspects of the environment (not only the harmful ones) permeate through them; on the other hand they exert an influance due to their material (physical and chemical) structure and to the finish,

3. internal factors having their source in the activities of the people within the residential environment (the use of household, equipment, various indoor operations, etc.), and also in people themselves.

755


In principle, the research stage of a variety of livability aspects of the residential environment has been finalized already, with a number of recommendations for partial solutions. Some further influences have not yet been found a satisfactory solution for. In particular, no criteria have been established for the usage of non-objectionable material and structures. Along with that, the process of investigating certain sets of combined influences in all their correlations has been started. An overall approach to the problem of residential environment is seen to be indispensable, because the overall influence on man is not by isolated factors, but by a complex set of factors.

Although the planning of residential and civic buildings will always contain some intuition of the planner, rooted in his creative individuality, it will be necessary to create such a residential environment that can not only meet objective criteria and good hygienic standards, but can also enhance the life style of its users through the ambience of well-being it inspires. This, of course, is an ideal assumption even under circumstances where the impact of certain microclimates and building structures upon man are fairly well known. The stumbling block resides in that there are often contradictory requirements from the viewpoint of building structures, based upon the diversification of physical substances and agents involved. Even if the influence of the quality of external environment is left out of consideration, the unlimited diversity of generally used building structures and materials presents a serious problem.

A solution is seen in making full use of interdisciplinary collaboration of physicians, microclimate experts, architects and civil engineers.

This research has been conducted at the Department of Building Design, Faculty of Civil Engineering, TU in Brno as part of the research project "Formation on the condition of the indoor environment in the school buildings" and has been supported by Ministry of Education, Youth and Sports grant No. PV OSS.

756


THE EVALUATION OF THERMAL-HUMIDITY

MICROCLIMATE IN CLASSROOMS OF THE ELEMENTARY SCHOOLS

D. Čuprová

TU, Fac. of Civil Eng., Dept. of Building Design Poříčí 5, 639 00 Brno

Key words: microclimate, school buildings

The measurement of the thermal-humidity microclimate (TIIM) was accomplished in school buildings of different construction types. The building of elementary school at Mendlovo nam. is a three-storey building made of solid brickwalls. The inner wall thickness is 300 mm, the outer wall thickness is S00 mm. The average ceilingheight of the classroom was 4.35 m. The heaters are made of cast iron connected to a steam healing system. The THM was measured in the classroom situated on the second floor, the windows are oriented to the west.

Elementary school at Labská is of the pavilion type structure. The building of the В pavilion, where the measured classroom lb is located, is a two-storey building made of a reinforced concrete with the peripheral mantle (covering) made of 250 mm thick ceramic panels. The inner partition walls are 125 mm thick. The room height is _\95m. The classroom windows are oriented to the west. The heaters are flat steel radiators placed below the windows.

The temperature of the air was measured by means of the Cu/Co thermocouples and the humidity with the detectors FH 9626. Up to 30 thermocouples were placed in the measured classroom on the inner and outer surfaces of the walls. The temperature of the air was measured at the height of 150 mm and 1050 mm above the floor together with the humidity and the temperature of the air immediately below the ceiling. The measured data were recorded by the measuring plant THERM 5500-3 (Ahlborn). Data collected on the registration card were evaluated on the PC in the form of tables and graphs.

As follows from the results of the measurement it is possible to state, that in both examined schools the internal temperature in the classrooms and in the corridors are a little higher than the values recommended by the standards for the elementary school buildings. However the recommended values of the temperature are surpassed only for short periods in the school at Labská around noon, because at that moment the thermal balance is influenced by direct solar radiation. In the afternoon the influence of the direct solar radiation is noticeable expressed in both schools, because of the westward orientation of the windows. More explicitely of course is the influence of the direct solar radiation noticed in school at Labská, because of the larger surface of the windows. In school at Labská, during the winter season for short periods the total values of the walls and the air temperature are higher than the recommended value of 38 "C.

The air humidity values in the classrooms are not stipulated in the standards, while for the buildings of the elementary schools the use of the air condition systems is not considered.

757


If we assume that for the thermal comfort at a temperature of 20°C the recommended values of the air humidity are 3<1%-S0% in the summer season and 30%—70% in the winter season, than for the maximum air temperature of the internal air t,max = 25.5°C, the threshold values of the air humidity should be in the winter season 21%-50% and 24%-5S% in the summer season. In the summer, the above mentioned values are met in the classroom of school at Mcndlovo nam. In the winter season the relative humidity, at the level of 1050 mm, falls however to the values between 16.8%-25.S%. In school at Labská the values of the relative humidity for the whole working time of the children are at the lower border of the recommended limits with some shorttime drops. The low values of the relative humidity may be considered as unfavourable since they support the dryig-otit of the mucous membranes in the respiratory tract and in this way may hamper their protective function against the microorganismes contained in the air the children breathe in.

In conclusion it is possible to state that in the school at Mcndlovo nam. more favourable values arc reached from the point of view of thermal stability, i.e. the temperature and humidity of the air which are important for the state of the thermal comfort. During the winter season it would be useful to increase the humidity of the air by means of humidificis.

The classroom in school at Labská has less favourable values in the thermal stability of the walls because of the structure of tlic peripheral mantle and the large surfaces of the windows. Therefore on sunny clays the internal temperature of the air increases over the highest admissible value of t imar = 25.5°C, as in summer so in the winter season. This problem could be solved in winter by suitable organisation of the heating process and the use of humidifiers.

This research has been conducted at the Department of Building Design, Faculty of Civil Engineering, TU in Brno as part of the research project "Formation on the condition of the indoor environment in the school buildings" and has been supported by Ministry of Education, Youth and Sports grant No. PV 022.

758


COMPARISON OF MICROCLIMATE VALUES MEASURED

BY THE MEASURING SET 'NOBAVI' AND THE MEASURING PLANT

L. Novák, D. čuprová*, Л. Navrátilová*, V. Božek*

MU, Fac. of Medicine, Dept. of Physiology Komenského nám. 2, 6G2 43 Brno

*TU, Рас. of Civil Eiig., Dept. of Building Designe Poříčí 5, 639 00 Brno

Key words: microclimate, thermal comfort, katathcrmometcr

The thermal comfort defined in the ISO 7730 by the Fangcr's equation, needs for the solution the measured values of radiant temperature, temperature, velocity and humidity of the air and the knowledge of the core temperature, metabolic activity and the thermal insulation of the body core. Of course, the vertical gradient of the radiant temperature together with the relative humidity and movement of the air at the level of the head is also one of the factors which plays a very important role in the perception of thermal comfort.

Our hygienic instruction HEM-340.2-30.9.77 is in general compatible with the basic trends expressed in the ISO 7730 (Jokl, Moos 1989). The measuring set of the globe thermometers used in our hygiene service enables the simultaneous measurement of the resultant temperature at two different levels (the ankles and the head), however it does not have the possibility to measure humidity and velocity of the air movement, values very important for the calculation of Fanger's equation according to the ISO 7730.

To remove the above mentioned insufficiency, we have supplied the set of the globe thermometers with two detectors of the electric dynamic katatlicrmoruelers (EDK), (Barák, Novák 1986), fixed at the levels of the globe thermometers. For the automatic registration of the all measured data (resultant temperature, temperature of the air and the katavalucs) the logger VILOG 5V (Veit electronics 1993) was used. Such extended measuring set enables the registration of all measured values with the preselected pace of data collection for all the week. For the on line watching, and also for processing of measured data the PC QUADERNO was used with success in the terrain measurements accomplished within the framework of the research project PV 022.

With the set described above, noted by the code name NOBAVI, we made a series of measurements simultaneously with the measurement of the temperature on the surface of the walls, the windows, the ceiling and the floor by the measuring plant THERM 5500-3 (AHLBORN). The practical aim of this communication is to demonstrate the compatibility of both ways of data collection and to compare in what extent are compatible the values of the radiant temperature calculated for the two levels (the ankle and the head) from data measured by the set NOBAVI and the measuring plant THERM 5500-3.

The data collected in the classroom of the elementary school at Labská street in Brno for the time interval from 6:00 to 14:00 hour for the whole week are summarized in six tables and six graph charts. The analysis demonstrates that the EDK sensors are the most

759


sensitive to the presence of pupils and their active movement during the pauses between lessons and to the ventilation of the classroom by opening the window and the door in the registration of the air movement. The reaction of the resultant temperature, and the temperature of the air and the temperature of the surfaces arc milder and delayed.

The calculated resultant temperature of the globe thermometers at the level of the ankles was between 22,I"C to 23/l°C, at the level of the head between 23.4°C to 24.9°C. The temperature of the air at the level of the ankle between 22.1°C to 22.'1°C, and at the level of the head between 23.5°C to 24.6°C. That means it was 1.ГС, higher at the level of the head.

The radiant temperature calculated from the surface temperature values measured by means of the plant THERM 5500-3 on the surfaces of the walls, the windows, the floor and the ceiling, show the values between 22.8°C to 24.6°C, and arc closer to the values measured by the globe thermometer at the level of the ankle. The difference between the values of the radiant temperature calculated from the data of the NOBAVI set and the calculated values of the radiant temperature from the data of the plant THERM 5500-3 is between —0.2°C to 0.4°C. However in comparison with the values of the radiant temperature calculated from values of the NOBAVI set at the level of the head the difference reaches the values between 0.7"C to 1.5°C, in all measured sectors. This difference is already significant at the level of p<0.01 for v=54. It is possible to consider that the value of the radiant temperature measured at the level of ankles is more influenced by the temperature of the floor, and the radiant temperature at the level of the head is closer to the air temperature at this level.

From the above mentioned we may conclude that the calculation of the radiant temperature from the data on the surface temperatures of the walls, the windows, the floor, and the ceiling measured by means of the plant THERM 5500-3 arc at the level of the head substantially different from the data measured by the set NOBAVI from the values of the globe thermometer and the air velocity. It is therefore important for the evaluation of Fanger's equation according to the ISO 7730 to use the values of radiant temperature measured at both levels (the ankle and the head) directly by the globe thermometers or with the simultaneous measurement of the air velocity as it is possible for instance by the the NOBAVI set.

References: [1] JOKL, M. V. - MOOS, P.: Optimal globe temperature respecting human thermoregula

tory range. ASIIRAE Transactions. Vol. 95, part 2, No. 3288, pp. 329-335. 1989. [2] BARÁK, Л. - NOVÁK, L.: The two channel electric dynamic katathermometer for

measurement of thermal microclimate inside the garmct. Scripla mcclica 59, 4, pp. 227-232. Brno 19S6.

77iis research has been conducted at the Department of Building Designe, Faculty of Civil Engineering, TV in Brno as part of the research project "Formation on the condition of the indoor environment in the school buildings" and has been supported by Ministry of Education, Youth and Sports grant No. PV 022.

760


SUGGESTION FOR INTERIOR ARRANGEMENT

TO OPTIMIZE DAYLIGHT ILLUMINATION OF THE CLASSROOMS

K. Cupr

TU, Fac. of Civil Eng., Dept. of Tccnical Equipment of Buildings Údolní 5, 639 00 Brno

Key words: daylight illumination, school buildings

Daylight illumination of the school interiors we consider the requests of the standards CSN 730580 '-Daily illumination of buildings" and CSN 360041 "Daily illumination of schools".

Within the research project PV 022 the coefficient of daylight illumination was investigated in classrooms at elementary schools. It was found that it is impossible to make a unanimous conclusion for the ideal classroom with definite dimension and structure. The results gained in different classrooms are impossible to apply so as to satisfy the demands of a newly designed classroom.

The level of the coefficient of daylight illumination is in individual classrooms influenced not only by the structure of the room, the setting of the illumination openings and their relation to the surface area of the floor and the depth of the room, but also by the configuration of the space in front of the object, the shade trees and other objects situated in front of the measured room.

This implies, the necessity to proceed always from one case to the other and the final proposal (plan) for the final layout of the interior, namely of the illumination openings to adjust for the particular situation.

There are four ways to achieve the desired level of the coefficient of daylight illumination in interiors which do not comply with the minimum required values.

1. More changes through reconstruction of the room. 2. By the exchange of one activity for another one, with smaller requirements for the level

of a daylight illumination. 3. By way of the supplementary artificial illumination. 4. By particular arrangements for the increase of the coefficient of daylight illumination.

In the first alternative it is possible to suppose, for instance, the increase of the window size or the exchange of the windows with the aim to increase the surface of the glassed area which is proportional to the coefficient of the sky-component of the coefficient of a daylight illumination. Such a solution has disadvantage because the room under reconstruction is for a short time out of use. Also the costs are relatively high, and the thermal qualities of the interior may be changed by such reconstruction.

The second alternative is out of the question for elementary schools, as the value of 1.5% represents the value required as a minimum for any classroom. (The specialised classrooms should have a minimum value of 2% or more, according to the standards for hygiene).

761


The third alternative is the most simple way for the improvement of the value of illumination of the interior. This arrangement of course disturbs the comfort of the environment. The daylight looses the preference in the illumination of the room. The illumination becomes to be associated one and should be licensed according to the standard CSN 360041 "Daily illumination of schools" and is granted only as the exception by a heath board. The artificial supplementary illumination increases the costs.

The fourth alternative represents the more complicated arrangement with strictly individual approach to the interior. The substance of such approach is based on changes of some factors, eventually on a set of various factors which lead to the partial improvement of the existing light-technical situation. Among the factors influencing the coefficient of a daylight illumination are

a) kind of glassing, b) degree of cleanliness of glassed surfaces, c) colours used in the interior.

To what degree these factors influence the coefficients of a daylight illumination is documented by results which are calculated from data measured in the classroom of elementary school at Mendlovo nam. in Brno.

This research has been conducted at the Department of Technical Equipment of Buildings, Faculty of Civil Engineering, TU in Brno as part of the research project "Formation on the condition of the indoor environment in the school buildings" and has been supported by Ministry of Education, Youth and Sports grant No. PV 022.

762


STUDY OF THE SHORT TERM FLUCTUATUION OF WATER

CONSUMPTION L. Macek, P. Zykan

CTU, Fac. of Civil Eng., Dept. of Sanitary Engineering Thákurova 7, 166 29 Praha 6

Key words: water consumption, short-term demands

This article deals with the monitoring and evaluating of short term changes of water consumption. Two main drinking water distribution areas were studied. In Mlada Boleslav (aprox. 50 000 inhabitants) the water use of two main pressure zones were monitored at 1 minute interval. In Kladno the results of the monitoring 5 selected closed areas of water distribution were studied. From the time scries of water consumption the plots of probability for water use were constructed. Л scheme was then proposed to improve the data for the design of a water distribution system.

The main reason for carrying out this study were

(a) to get the real pattern of water consumption in a very short interval (b) to find out if there were some important changes of water use in this short interval (c) to analyse the monitored data to construct probability plots of water use

Water use in 1 minute interval Wednesday 01/01/92

I sř w

rtř\^4li Х'*'Чл»'г

n, A

\:~ « 0 0 MOO IOOO 1200 1400 ItOO 1100 20 00 2100 0O0O 02 00 MOO

O/Ol] U9U0 1100 1300 1300 1200 t« 00 2100 23 00 U1 00 OJ 00 In Ul

ttfijlac I

Hi «JIM II

Time (h)

Fig. 1: Monitored changes of water use, January 1st, 1992, Mladá Boleslav

One of the results of this study is demonstrated in Fig. 1 where the plot represents changes of water consumption on January, 1st, 1992 at Mlada Boleslav. There the beginning and end of the film "Vesnicko ma středisková" by Jiri Menzel can be identified. Two periods of a sudden increase in water use can be observed. The measured maximum was at least

763


2.5 time higher than the average water use, with the increase of water consumption 100 l/s in a period of 5 minutes.

The data of water consumption was analysed in several ways. Some of the results of data analyses can be seen in Fig. 2. From the probability plot of water use vs. interval of water use it can be deduced, that for the design of a water distribution system another system of water demands fluctuation can be used. In small areas of water use with less importance it is possible to use the coefficient of imbalance with higher probability. The important parts of water distribution systems such as the town centres and residential areas with large blocks of flats should be designed on the basis of water use of lower probability.

Probability of water use Propaefc, 10/6 - 8/7/92

- nw*Ml '01% - « » И »

Time (min)

Fig. 2: Probability of water use: water use vs. time intervals

References: [1] SIWON, Z. - STANISLAWSKI, J.: Ueber die stochastische Wasserbedarfsprognose in

Stadlen als Basis zur Steuerung und Kontrolle von Wasserversorgungssystemen. GWF Wasser, Abwasser, 129, H3, 1988

[2] MACEK, L. - ZYKAN, P. - SEDLAČEK, J. - NOVOTNÝ, Т.: Nerovnoměrnost odběry vody. SOVAK, No. 7-8, p. 33-34, 209, 1994.

This research has been conducted at the Department of Sanitary Engineering as part of the research project "Study of short-term fluctuation of water consumption" and has been supported by the Faculty of Civil Engineering's grant No.2096.

764


AIRBORNE RADON CONCENTRATION AND DOSE RATE

IN THE PRAGUE METRO J. Sabol

CTU, Fac. of Nucl. Sci. & Phys. Eng.. Dept. of Dosimetry & Appl. of Ionizing Rad. Břehová 7, 115 19 Prague 1

Key words: airborne radon, dose rate, Prague metro, radon concentration

The ionizing radiation to which the population is exposed comes from natural and man-made sources. About S5% of the total effective dose is due to natural radiation sources which include cosmic rays, external radiation from radionuclides in the earth's crust, and internal radiation emitted by radionuclides inhaled or ingested and retained in the body. In the Czech Republic, the individual average annual effective dose from natural radiation is estimated to be 2.8 mSv, of which about 1.3 mSv is from the following three sources: cosmic radiation (0.35 mSv), terrestrial radiation (0.55 mSv) and internal contamination (0.25 mSv). The rest, 1.5 mSv results from exposure to radon and especially to its decay products. The contribution from radon and external penetrating radiation depends on local geology and building materials as well as on the ventilation and isolation of dwellings and other closed spaces where people live or may spend some time. One such place, which is expected to show enormous variations in radon concentrations and levels of external radiation fields, is the Prague metro.

The metro network in Prague consists of three lines А, В and С of 45.1 km with 46 stations situated in the depth ranging from virtually zero to more than 50 m. The deepest location is at the station Nám. míru, 52 m below the ground. The metro can serve about one million commuters every day.

There are some important factors influencing the level of radon concentration in the metro stations and on the trains. The hermetical isolation against water leakage and intensive ventilation will probably result in the reduction of the radon level. Heavy shielding of concrete or steel lining in the tunnels as well as the strong construction of the metro carriages are presumed to decrease the level of gamma radiation emmited by the surrounding rocks. At the same time, the substantial thickness of the earth's layers will act as an efficient shield against cosmic rays whose muons are the major component of exposure from this source.

In order to assess the exposure of metro passengers under normal conditions, the radon concentrations as well as the dose rate due to external radiation were monitored. Radon surveillance was carried out using a digital monitor based on a pulse ionization chamber (AlphaGUARD), while the measurement of the dose rate profile was accomplished by a compact monitor with two energy compensated GM counters (GammaTRACER).

The result of monitoring are summarized in Fig. 1 where the ranges of radon concetra-tions and dose rates in the metro stations and trains are given. For the purpose of comparison, both quantities were also measured in other locations, both outdoor and indoor, including a typical house in the centre of Prague. It has been shown that the exposures of

765


the metro passengers are at least two times lower than the doses received outside the metro during the same time interval.

ISO

100

: so

106-130

M-100

72ZZZZZ

26-48

131-142 777777Г<77Л777?1 123-127 123-127

7ZZ2ZZZZ 132-138

Fig. 1: The ranges of airborne radon concentrations and dose rates in air at various typical locations and places: Л - outdoor (Centre of Prague), В - underground stations of Prague metro, С - metro trains, D - the basement of a brick block of flats, E - the living room with normal ventilation (floor 3, house - see D), F - the living room closed (the same house as D), G - balcony (see D).

This research has been conducted at the Department of Dosimetry as part of the research project "Assessment of Radiation Situation in Prague" and has been supported by CTU grant No. Щ12.

766

Section 15

ARCHITECTURE,

URBANISM

& :

VISUAL ARTS

WORKSHOP 95 ARCHITECTURE, URBANISM & VISUAL ARTS

WORK IN THE OPEN AIR IN FRANCE AND ITALY

Jiří Sobotka

Faculty of Fine Arts, TU Králova 45, 616 00 Brno

Key words: plcin air — summer workshop — France; study stay — northern Italy

Work in the open air is one of the important forms of study at schools of fine arts. In the academic year 93-94 our faculty obtained two offers of stay abroad including

work in the open air. Besides this there was also a possibility to experience working in environment totally different from that in this country.

In the first case two students and one teacher (Jiří Sobotka) were invited to the annual summer workshop at the Bretagne shore near Lorient and on the island of Belle He held in May, 16-29. This invitation and also the exhibition of sculptural works of Jiří Sobotka in the gallery of Ecole des Beaux Arts in the same period were the results of the first contacts with Ecole dcs Beaux Arts Lorient (the school of fine arts in Lorient).

Plcin air on the island of Belle lie brought the students stimulating impulses. Besides it was also a good occasion to work and to communicate with colleagues from other schools of different countries. In spite of the expectation the most important thing at the Workshop was not the traditional landscape but trying to give the shape to the sensation of the place, being aware of the space and the scale on the basis of the authentic experience.

Not only the work in the open air but also a very interesting programme focusing on visits to some important art monuments (Kerguehennec — sculptural park, Carnak — museum of Neolithic arts) in the surroundings of Lorient was arranged for the students to widen their cultural horizon.

During the stay in Lorient I (Jiří Sobotka) took — as a teacher — the opportunity to visit Ecolc des Beaux Arts and to acquaint myself with the curricula and with the way of teaching in individual studios. There I could also watch the level of the students' work and compare it to the work of the students of our faculty. 1 also obtained much experience in organizing the work in the open air just at the time when a project — Summer Sculptural Workshop at Orlík Castle — based on the work in the open air was being prepared by our faculty.

The second project was the work and study stay of 13 students of painting with their two teachers in northern Italy. During the period June, 8-29 they painted in the open air near the village of Belforte in Toscania. This area is well-known for its cultural past and the famous art centres (Siena, Firenze, Padova).

Besides the opportunity to paint in the open air in the Toscanian countryside with the southern Mediterranean light, the intention also was to give the chance to the students to compare their own works to the works of some famous Italian Masters whose paintings portray the same Toscanian countryside. The students acquainted themselves with works of these Masters during the intensive visits to museums and galleries of the historical towns of Firenze and Siena (Galleria dell' Academica and Galleria degli Uffizi in Firenze; Pinacoteca Nazionale, Museo Civico and Museo dell' Opera in Siena). Besides this close contact with artistic works of such Masters as Boticelli, Giotto, Michelangelo, Leonardo da Vinci etc. the

769

WORKSHOP 95 ARCHITECTURE, URBAN1SM к VISUAL ARTS

students met nearly every evening to listen to the talks of academic painter R. Kutra — their teacher — and to discuss the theme "Reflection of the Toscanian countryside in the works of the famous renaissance Masters".

This kind of projects have a great importance for these future artists and maybe teachers in this field. Experiences and impressions gained during such stays play role in the process of forming and moulding their personality and it will sooner or later reflect in their artistic works.

This research has been conducted at the Faculty of Fine Arts of the Technical University of Brno as part of the research project "Work in the open air — France, Italy" and has been supported by TU grant No. С 28/94-

770


INTERNATIONAL SUMMER SCULPTURAL WORKSHOP

AT ORLÍK CASTLE Vladimír Preclík

Faculty of Fine Arts, TU Králova 45, 616 00 Brno

Key words: encouragement of instruction at schools of fine arts

In August, from the 8th to the 31st the first Summer Sculptural Workshop at Orlík Castle was held. This event is part of a programme focusing on the development of an international liaison between the Faculty of Fine Arts in Brno and some European academies of arts. Students of five schools including our faculty took part in the Workshop this year (Hochschuie fiir Angewandte Kunst Wien, Akademija likovnih umjetnosti Zagreb, Akademija za likovno umetnost Ljubljana, Akademie fur Bildende Kunst Kiel, Fakulta výtvarných umění VUT Brno).

Organizers from the Faculty of Fine Arts intended to offer each participating student of sculpture:

• to work on a sculpture on a larger scale than is usually possible during work in the studio at school; work material was free

• the opportunity to work in the international group of sculpture students of the same age for the period of three weeks

• a chance to exhibit permanently his or her sculpture - created during the Workshop - in the setting of the castle park at Orlík Castle - the ancestral home of the Schwarzenbergs'

We endeavoured to provide good working conditions, accommodation and board to all invited students so that they could work with enthusiasm without worrying about material things.

Results of the work of nine young sculptors enable us to consider this Workshop as more than successful and very necessary.

This research has been conducted at the Faculty of Fine Arts of the Technical University of Brno as part of the research project "International Summer Sculptural Workshop at Orlík Castle" and has been supported by TU grant No. С 35/94-

771


PRESENTATION (INSTALLATION — ACTION)

Tomng Ruller

Faculty of Fine Arts, TU Králova 46, 61G 00 Brno

Key words: multidimcdia inter-actions

The experience with installations in which objects arc manipulated mechanically, which, like "nature niorte" suppress the living reality, led mc to processes of installing as active contemplations of the generation, transformation and death of shapes, Similar to poured mandala.

The installation "Big Bang" involved loose glass panes making a "house of cards", an unstable state of potential energy in danger of a spontaneous fall. In LA. I emphasized the instability by installing the panes in front of the audience, and one viewer, even before the opening ended, smashed the construction with a hammer, which tied the tension to the centre of gravity.

Rigorous followers of the idea of artwork as an object, suggested to accuse the viewer for clestructiofi of an artifact. However, since the very structure of the work included the process of form creation, I also accepted its extinction in time, The splinters represented the "Big Bang" as "relict radiation" during the exhibition. At the same time they were still' part of the existing overall construction.

Residual elements of a disintegrated structure show a difTercnt condition. "Touched objects" differ from an exterior description of an event (written account, video recording etc.). Similarly the magic law of inner harmony can be divided into a contact one (based on the principle of touching), and an analogical one (based on the principle of resemblance). Both true only if there is a distance from the original being.

The elements of the disintegrated whole can either be left to the stream of self-transformation, used in new works, or be conserved and become a relics. The question of the "museum principle" is therefore connected with the phenomenon of "fetishism" affecting not only visual art.

Presentation as an action is carried out by purely practical operations. The act of giving oneself to the open process of precarious transformations lent a new orientation to the original fragmentary structure and implicated order from chaos through the process of distilling. Such a "Gestalt" has inner purpose and a structure that is analogical rather than allegorical.

Such a work of art is not possible to handle as an object, as it is a process of presentation, experienced through activity of performance.

With such works one cannot define any physical means, as they are in fact intermedial. Such works are not series of acts with a mission but multi-dimensional fields of possi

bilities. The text of such a presentation brakes the distance between "writing" and "reading"

in that the viewer-participant is involved in the creation of the meaning. This is not a reading in the sense of consuming but playing with the "text". The author abstains from his supreme position and becomes a co-author on the same level with the viewer.

773

WORKSHOP 95 ARCHITECTURE, URBANISM к VISUAL ARTS

What is involved is not only a transformation of the role of the artist but also a transformation of the whole system of values, paradigms and views of the nature of reality as a whole, together with the practical approaches to it. It is fin attempt to save phenomena, an effort to absorb fully what becomes apparent through the phenomena of this world. In terms of philosophy it is an attempt to transcend post-modern skepticism.

If matter is a structured emptiness of phenomenal (ctheric) nature and if being has an inner form, then a trust in the essentiality of transitory forms is to be raised.

The treatment of the inner nature of being is not aiming the manipulation with magic forces, the employment of magic power, but the participation in the creation of reality, with gaining the consciousness of unity in which the creator, creativity and the created arc functions of the same principle of creation.

Reality realized in deed is fascinating. What remains is the question of the relation of traces, path and destination. Transformations of dynamic systems involve scale changes. That is why definition of

limits, the field of development, the frame, is a precondition of the final form. In the course of the creation of the final form (Gestalt), parts emerge together with the whole in coherence within the order which implies them.

This research has been conducted at. the Faculty of Fine Arts of the Technical University of Brno as part of the research project "Multimedia inter-actions in diyitalized environment" and has been supported by TU grant No, 37/93 F.

774


THE ANALYSIS OF THE NAVE VAULTS IN THE CHURCH OF OUR LADY'S

ASSUMPTION IN NOVÁ PAKA AND ST KLARA'S CHAPEL IN CHEB

M. Pavlík, P . Dvořáček*

CTU, Fac. of Architecture, Dcpt. of History & Theory of Architecture Thákurova 7, 166 34 Praha 6

*CTU, Fac. of Civil Eng., Dcpt. of Mapping & Cartography Thákurova 7, 166 29 Praha 6

Key words: architecture, photogrammetry, vaults

Both the architectural compositions belong to the group of buildings of Guarini's type in Bohemia. After surveying the vaults of St. Mikulas's Church in the Malá Strana in Prague, St. Markcta's Church in Břevnov, Prague, and St. Josef's Church in Obořiště, the architects started to examine the nave vaults in the Church of Our Lady's Assumption in Nová Рака and in St. Klara's Chapel in Cheb. The research on vaults and spatial units, which still draws the attention of many specialists in art in Europe, thus comes to an end.

The church in Nová Рака was founded by the builder P. Blažejovský in 1709. The vault consists of five parts. The central bay and the two outside ones arc shaped as irregular Bohemian vaults. The areas in between them are arched again in the shape of Bohemian vaults. The characteristic vault features are defined by arches where the vaults meet, which correspond with the arches on the vault back. Furthermore, the backs of the vaults are reinforced by diagonal ribs at the largest central bay, and by a double vault layer at the linking bays, which seem to be elongated over the basic vault structure.

The vault plan of the long chapel hall in Cheb (170S-11) is designed with the intersection of two transversal ovals with a smaller one. This type of vault is best seen in a contour plan; this clearly shows how it is related to the vault system examined in the last phase of the grant research (St. Josef's Church in Obořiště).

The authors (unlike in above methods) want to determine the actual state with the utmost accuracy. Taking this as a basis, they draw the necessary conclusions for the spatial concept of these late Baroque buildings. Considering the character of work, the stereopho-togrammetrical method was again used to survey the ceilings. The photography positions were always chosen to be on the floor; the photograph axes were directed vertically to the top. This requirement had to be kept with the utmost accuracy, so that the stereo pairs could be considered as a standard case of stercophotogrammetry. Thus, it is possible to use the analog plotting instrument of Technocart.

The universal metric camera of UMK 10/1318 (Carl Zeiss Jena) was used for taking photographs; a wide-angled objective enabled to choose the photography positions along the main axis of the nave; the whole ceiling from the main cornice to the top could be included in one series of pictures. In the Cheb church there were two stereo pairs. It was necessary to photograph the ceiling of the church in Nová Рака with three stereo pairs because of the main vault dimensions, and the camera was placed on the floor without a tripod.

775


Considering the needs of the model orientation in the plotting instrument as well as for checking, ground control points were always plotted. These were usually the break points of the main cornice.

The processing and photogrammetrical plotting was performed in a photogrammetry laboratory of the Department of Mapping and Cartography. The graphic system of KOKES was used for the calculation of the control point coordinates. The photogrammetrical plotting with the Technocart included two outputs: - a direct graphic output on a drawing board - the registration of the spatial [model] point coordinates on a registration device.

The second method enables us to transfer the set of model point coordinates to a computer using usual graphic systems. In our case, the set was transferred into the format of STX, which is used by the KOKES system. After transferring all model spaces into one coordinate system, the acquired set of points was also transferred into the digital terrain model of Atlas. Through this system we can illustrate the topographical area in the form of contour lines, as well as in the form of sections. It is possible to determine the density of sections, and in this way to present the shape of the topographical area in a three-dimensional space using parallel or square sections.

The photogrammetrical method proves to be an effective and available procedure for surveying the spatial shape of building parts of this type. The achievable accuracy of 0.02 m in determining the spatial position of a point is sufficient for the survey results to become a reliable basis for further special evaluation.

The further improvement of photogrammetric survey can be conducted in two ways. First, analytic photogrammetry methods can be used (there arc more possibilities in choosing different photography stations and photograph axis directions - the vcrticality of photograph axes is not necessary). Second, il is possible to use other, more precise graphic systems for the presentation of the topographical area shapes.

References: [1] NAŇKOVÁ, V.: Dějiny českého výtvarného umění Praha 19S9 [2] PAVLÍK, M. - ŠÍMA, J.: Příspěvek к otázce zaklenul! lodi kostela sv. Markéty v Praze

Umění XVII, 1969 [3] PAVLÍK, M.: Rozbor klenby lodi kostela sv. Markéty v Praze na základě fotogrammet

rického zaměření Sborník statí, FF Praha, Milénium břevnovského kláštera [4] PAVLÍK, M. - DVOŘÁČEK, P.: Analysis of Nave Vault in SUoseph's Church at

ObořišléCTU Seminar 94, part B, 221-222, CTU Praha 1994 [5] FOUS, P.: Fotogrammetrické zaměření klenby barokního kostela Diplmová práce ČVUT

FSv, Praha 1994

This research has been conducted at the Department of Theory & History of Architecture and the Department of Mapping & Cartography and has been supported by CTU grant No. 18Щ.

776


PRESERVATION AND NEW FUNCTIONAL USE

OF INDUSTRIAL HERITAGE

H. Zemánkova

TU Brno, Fac. of Architecture, Manuf. and Util. Construct. Inst. Porici 5, 6G2 83 Brno, Czech Republic

Key words: conversion, new functional use, industrial archeology, industrial heritage

Since the beginning of the last century, similarly as in a number of industrial towns abroad, also in our towns complex relations have developed between the housing areas and production units. This problem lias not been dealt with in this country until recently. A conception of territorial planning for new factories was not created and the significance of their further development was not recognized even in the post-war period. The factories destroyed by the war actions were reconstructed even if their existence was in gross contradiction to their position in the vicinity of town centres. These production units were utilized, sometimes without being substantially modernized until the nineties. In the western developed countries, on the other hand, the post-war rate of changes in town-planning was increased. The decline of the outdated factories from the era of industrialization, which had been the driving force and moving power of many towns and which, like in this country, were mainly situated in the vicinity of their centres (textile industry in the northern parts of France, ship-yards in Nantes, docks in London, ...) had devastated extensive areas. Incorrect applications of town-planning instruments brought about extensive demolitions. Old production units were pulled down to make room for more important functions on lands saturated by engineering networks increasing their prices in central town areas.

It was not until the seventies that the attitudes of town-planners but also of enlightened mayors and members of parliaments towards the industrial heritage — factories which had lost their functions — bagan to change. This new attitudes are connected with the criticism of big monofunctional sets both civil and productive and with difficulties in acquiring new lands by demolitions. However, the quality of the industrial architecture of the last two centuries worth preserving also plays an important role. The new approach is documented by towns such as Lille and Roubaix in France, which, by functional transformations of old textile factories, inject dynamics into their centres stabilizing jobs and population growth. The new approach can also be seen in other towns such as London, Milan Torino, Helsinki which initiated a revitalization of their centres starting from the existing buildings. Their new functional use is a conscious architectonic and town-planning creativity and it can be a better contribution to the town than their preservation as monuments.

The changes in the structure of society and economy in this country in the last five years have led to terminations of non-prosperous production units, which, even in our conditions, entails the existence of first freed production areas and factories (mining industry in the Ostrava region, sugar factories in South Moravia, textile factories in Brno). The persons deciding about ways of dealing with the industrial heritage, members of parliament or city councils, building authorities, owners are not yet prepared for subtle decisions on the preservation of these objects. They do not see their importance in the structure of settlement

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WORKSHOP 95 ARCHITECTURE, URBAN1SM к VISUAL ARTS

and their esthetic and economic values despite a number of inspiring examples abroad. Thus, provisional utilisations and demolitions of these objects still occur.

At the Faculty of Architecture, students majoring in Conversion work on a research project entitled Preservation and New Functional Use of Industrial Heritage. Since it can generally be said that as yet no systematic attempt has been made at solving the problem of documentation and evaluation of the industrial heritage, 1, as the leader of the student team, directed the work towards its mapping. In cooperation with experts from Brno Technical Museum and State Institute of Monuments in Ostrava they have suggested a unified form of documentation in the catalogue and a way of selecting representante of production activities and endangered objects. Surveys and gathering documentations of significant industrial objects and areas in Moravia, participation in creating their catalogue, suggestions for a revitalization to upgrade the heritage, the art of applying the methods of conversion, these are all parts of a process of preparing young experts for dealing with current problems in the area of conversions, which forms their positive attitude towards the industrial heritage. The catalogue also points out the history of value and architectonic quality and it should contribute to the decisions on the fate of buildings and areas.

The question of documentation and evaluation of the industrial heritage is closely connected to the methodology of its protection and renovation. In this way, the Technical University of Brno becomes an instrument and inspiration for the municipal authorities and other owners in decisions about deserted factories.

References: [1] ROBERT, P.: Reconversions, Adaptations, New Uses for Old Buildings Moniteur, Paris

1989 [2] GRENIER, L. - W1ESER, H.: Les Chateaux de I'lnduslrie Moniteur 1979 [3] HILL, В.: fronbridge Gorge Museum Trust 1990

This research has been conducted at the Department of Architecture of the Technical University of Brno as part of (he research project "Preservation and New Functional Use of Industrial Heritage and has been supported by TU grant No. F769S.

778


THE CONCEPTION OF TEACHING "THE STRATEGY FOR DEVELOPMENT

OF TOWNS AND REGIONS" Л. Mansfeldová

CTU, Fac. of Civil Eng., Dept. of Town & Regional Planning Thákiirova 7, 166 29 Praha 6

Key words:

The change in social and economic conditions which occurred in Czechoslovakia in November 1989 has, amongst other things, brought principal changes in the system of education: some existing programmes have been reconstructed and new ones have come into existence; the aim of this exercise was to prepare not only experts with a good professional education, but to prepare educated people in the wider sense of the word.

One of the branches which became the subject of extensive professional discussions, as early as 1990, was the planning and management of regional development with a view to educating university graduates in this field.

Mastering a complex, not only a technical way of solving the problems is of particular importance to those who deal with the creation of the environment through construction, who decide on the exploitation of non-renewable resources, like regions, who locate the results of their activities into the landscape or into the existing residences cultivating or devastating thus the environment.

In 1991 the Department of Town and Regional Planning was established at the Faculty of Civil Engineering in the Czech Technical University whose aim remains to prepare specialized experts with an interdisciplinary professional view on communal politics, regional development etc., who are also able to make qualified decisions, concerning regional development at the different levels of administration, beginning with the local councils.

Therefore such newly trained experts must be given — besides their technical knowledge — at least a rudimentary training in the human sciences (such as philosophy, politology, sociology), town planning and architecture and be generally informed about economic and legislative problems as far as construction, financing and administration of the designated region are concerned.

The concept behind the tuition (lessons, seminars, projects) and the subjects included in the module "TOWN and REGIONAL PLANNING", ofTered by this department, are based upon the idea of closely linking both science and research with tuition and with the practical application of knowledge in the given area, in order to give the students a sophisticated approach to design and an awareness of all the relevant factors.

The aim is also to provide the students with information in fields other than just technical fields and to show them how to apply their knowledge where it is relevant to real concrete problems in town and regions. Such fields include sociology, ecology, economics and law. The students should also be enabled to work independently and creatively as well as in teams, respecting each others individuality.

The instruction of the students includes also the management of construction practice, in accordance with the contemporary social demand: the graduate is supposed to excel

779


in his branch, but also in organisation and business. The overall aim is to assist in the formation of new type of training for the school's graduates, concerning the general level of their professional education.

The method of education: lectures concentrating the maximum amount of information in relation to the main principles and circumstances, in cooperation with experts as teachers of specialized branches in order supply the greatest possible actuality of information — for example, concerning legislative regulations.

Both the work done in seminars and the work for projects deal with problems in concrete situations. This work requires of the student proper presentation of the results, including "defence" of them in front of their colleagues.

This helps them to get to know each other and enables them to develop the art of "conducting a dialogue", of accepting criticism and of defending and asserting the results of their own work.

The first graduates in this branch will finish their studies in 1995. Having undergone the required period of practice they will be able to get their authorisation in the field of "urban engineering" within the Czech Chamber of Engineers.

This research has been conducted at the Department of Town and Regional Planning and has not been supported.

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WORKSHOP 95 ARCHITECTURE, UR13ANISM & VISUAL ARTS

VILLAGE RENEWAL: URBAN AND ARCHITECTURAL ASPECTS

M. Martinek, J . Kozel

TU, Fac. of Architecture, Country Architecture Institute Poříčí 5, 639 00 Brno

Key words: urbanism, architecture, village, renewal, landscape, rehabilitation, planning, rural, agricurtural, building, folk, house

In the project, a number of examples of studies and projects for the renewal and development of selected rural villages and the adjacent areas are presented. The principal changes of socio-political and socio-economic conditions in the Czech Republic require new approaches to adrcss the issues of rural areas.

Rural transition from a centrally-planned economy to a market economy is a complex long-term process for which technical briefs must be prepared.

The project has five sections which follow one another. Each section consists of a text and graphic annexes. The text contains a short description of knowledge acquired from investigations and analyses. It is followed by the description of Czech and foreign experiences with recommendations adapted to the conditions in the Czech Republic.

The first section which covers the history up to the present deals with the historic development of the territory and settlement in question, adrcsses the cultural heritage of urbanism and architecture in rural areas, gives examples of possible utilizations of listed buildings and groups of buildings in the course of landscape and rural-settlement rehabilitation, examples of possibilities of using traditional elements of folk architecture for village houses and village renewal.

The second section contains the starting points for the solution of the assigned task as relating to the humanities, trends of demographic, social and economic development, experiences and examples in renewal planning and village development in the Czech Republic and abroad, worldwide trends in this field, and identifies the basic philosophy of how to approach the solution of this task.

The village renewal, which forms the third section of the project, gives the characteristics of a rural settlement - village, its position and function within the pattern of settlement in the Czech Republic, the history and development of the rural settlement in selected regions and localities, the administrative arrangement of villages, the urban and architectural values of rural settlements, their analysis and land uses, with a proposal of principles of the urban and architectural order of rural settlements.

The fourth section, called Village House, deals with dwellings, agricultural, manufacturing and other village buildings in terms of their architecture, lay-out, structure and materials used for their construction.

In addition, it contains the analysis of the structural state of buildings and groups of buildings existing in the area of interest, assesses the usability of the existing building stock, identifies the most suitable materials and structures convenient for various rural regions and structures.

Requirements for community facilities, buildings for agricultural production and other buildings in a village have been analysed in terms of their size, operation, lay-out, material

781


and architecture. Part of this section is a number of examples illustrating the village houses and the lay-out of other farm buildings in villages.

The closing section sums up the individual proposals, ideas and recommendations, and identifies the possibility of using them in teaching programs at schools of architecture and civil engineering, in research, in the preparation of planning documents for the development of rural settlements and for landscape management. Giving a number of concrete exemplcs, it can also serve as an aid, instruction and advice to district authorities (their departments of regional development), central authorities and, most of all, mayors and local authorities in the process of decision-making.

The experiences obtained during work on this project suggest that factors which can positively affect the evolution of rural areas include, first of all, the following: - the attitude of society to rural areas, the awareness of its importance, function and the necessity of

, using it in a purposeful and sensitive manner, - the changes in the hierarchy of values of life within rural population, particularly the increasing awareness of good-quality environment, health, a healthydiet and housing in immediate contact with nature, - the rate of technical progress will encourage the interest in living in villages, especially through improving the access of smaller and remote rural settlements to information sources (telecommunications). Consequently, it appears plausible that up to 20 per cent of the economically active rural population will not have to commute to towns, but will work for their employers at home, - scientists dealing with rural issues forecast a great future for rural areas. These areas can provide society with a number of activities which will be very attractive and interesting for the urban population, both for the young and the old - bringing up children in a healthy environment and in contact with nature, affordable housing for low-income groups etc., - possibilities of leisure-time activities enabling active relaxation through growing fruits, vegetables and breeding small domestic animals and the like, - in a broader sense, the task of village renewal includes, among others, the removal of space-related acsthetical structural and environmental defect.'*, thus improving general living conditions and the environment of rural settlements.

References:

[1] KISTENMACHER, H. - SLEPIČKA, A. - MATOUŠEK, V.: Vergkich der Zen-tralortlichen Systéme BRD/ČSFR. Universitat Kaiscrslautcrn 1992.

[2] SLEPIČKA, A. - MATOUŠEK, V.: Sicdkngssiruklnrellc Enlwickhng der Raumpla-nung in der Tschechoslowakei. Bcitrage der ARL, Band 119, Hannover 198S.

[3] MATOUŠEK, V. et al.: Dosavadní vývoj a tendence rozvoje sídel и CSSR. VÚVA Brno 19S6.

[4] SLEPIČKA, A.: Přeměny venkova/venkov našeho věku. Nakladatelství Svoboda Praha 1989.

[5] DOMBHARDT, H. J. - JACOBY, C : Speziclle Metlwden der Regional und Landes-planung. Universitat Kaiserslautem 1991.

[6] KISTENMACHER, H. - KURSAWE, S.: Der Rcgionalc Grunzung ung seine Bedeutung fur den Frciraumschutz. Universitat Kaiserslautem 1992.

782

WORKSHOP 95 ARCHITECTURE, URBANISM St VISUAL ARTS

THE RELATION OF THE URBAN SPATIAL STRUCTURE

AND THE TRAFFIC NETWORK OF BIG CITIES

J. Gřegorčík, J. Pavlíček*, M. Konvička, G. Kopáčik, К. Pazourek*, D. Wendscheová

TU, Fac. of Architecture, Dcpt. of Urban Design Poříčí 5, 662 S3 Brno

*TU, Fac. of Civil Eng.„ Dcpt. of Road Veveří 95, 662 37 Brno

Key words: urban spatial structure, traffic network, big cities, urban environment, urban value of the teritory, environmental district, optimum arrangement of streets, harmony of the town and the traffic

The enormous increase of traffic in towns meant more mobility and higher intensity of residnetial distribution of work, at the same time however it also created a series of conflicting situations in people's every day life, it disturbed their living environment, it disturbed the towns as entities and their working ability.

The experience from the control of traffic and from planning the development of towns demonstrate that ensuring the harmony between the traffic and the town represents one of the most serious problems of contemporary communal policy. This problem involves two levels of treatment. On the social level it is a question the social, economic and cultural problems of the process of town planning, of the possibility to control this process and in this way also of its influencing the growth of towns. Further more it is a question of value orientation in the approach of society to economic development, to protection and creation of the living environment and to the development of traffic. On the level of control of the operation and developtment of the town it is then a question of selecting the optimum traffic system, of ensuring the safe traffic and of removing the negative influences of traffic on the urban environment. It is especially possible in case of ensuring the harmony between the town structure and the traffic network, between a good organization of the operational exploination and the preservation of an acceptable level of urban environment on the given territory.

We propose to consider the degree to which we can ensure the harmony between the town structure and the traffic network as a sort of "Urban Value of the Territory" which may be determined by means of the following criteria:

- functional use - traffic - spatial shaping (cultural values) - environment (hygiene, good humour and safety). The determination of the urban value of the territory will serve as objective starting

point for establishing the proposal of its restructuring, reconstruction or for a proposal to change its traffic organization. By means of a collection of pattern criteria it will be also

783


possible to evaluate the possible variants of a proposal of adaptations of the town structure by the method of multi-criteria evaluation.

The evaluation of the relation of the town structure and the traffic network of a town may be realized on three levels :

1st level — the city street as characterized by the arrangement of buildings, open spaces and communications and their use through residential activities and traffic. The evaluation is oriented to the bearing maximum capacity of the street profile for traffic. The evaluation may express the limitation or the possibilities of enlarging the functional use and of the traffic of the municipal (urban) street or also the need for its reconstruction.

2nd level — town planning structure as a typological section or urban territory characterized by the land coverage as used at its historic period and street network and their exploitation by residential activities and traffic. The evaluation is oriented to the bearing power of the town planning structure for traffic. The evaluation may determine the territory which from the point of view of functional facilities and traffic is self-contained. These territories are called the "environmental districts". They may become the basis for the design of a new town planning organization of the territory. On the perimetrc of these districts only there should be the municipal communications that ensure the traffic between city districts.

3rd level — the town as a rcsisdential entity as characterized by the system of development and open spaces, by location and allocation of residential functions and the systems of traffic with the main municipal communications. The evaluation is oriented to the maximum capacity of the town as a residential entity for its traffic. The evaluation may - on the basis of the analysis of urban structure and traffic network - determine the urban values of the whole territory of the town and may define a territory stabilized as to its environment. On the other territories and on the perimctrc of environmental entities it is then possible to define the traffic corridors that are the base for creating the system of the main city communications. The value of the town may also express the needs for its functional restructuring whose application is desirable for achieving a more rational residential distribution of work, limitation of mobility and in that way a higher effectiveness of traffic. The evaluation may also in case of the town express the needs for reconstruction of its urban structure. This is important where it is not possible to adapt the town to new needs just by means of organizational measures.

The research was oriented to the evaluation of the 1st and 2nd levels. For them the research proposed the system of evaluation, the typology of urban structure and traffic network. Further on were designed the principles for optimum arrangement of city streets and the principles for optimum arrangement of the town spatial structure.

The research also expressed the preconditions for the treatment in harmony of the town structure and the traffic networks on the level of th whole town. The solution of these problems was offered for the Research Program of th European Comrnision COST 616 and the project was accepted. In this way the continuity and of final elaboration and use of the whole collelction of problems will be ensured.

This research has been conducted at the Department of Urban Design, Faculty of Architecture and Department of Road of Civil Eng., TU Brno as pari of the resaerch project "The Relation of the Urban Spatial Structure and the Traffic Network of big Cities" and has been supported by TU grant No. E 13.

784


REGIONAL PLAN OF CONCEPTION OF INTEGRATION OF SOUTH

MORAVIAN AND LOWER AUSTRIAN BORDER REGIONS

M. Kyselka, J . Kratochvíl*

TU Brno , Fac. of Architecture, Porici 5, 662 83 Brno

*TU Brno, Fac. of Civil Eng., Veveri 95, 662 37 Brno

Key words: regional plan, integration of border regions, landscape

Summary of Studies completed by the Faculty of Architecture and the Faculty of Civil Engineering Technical University of Brno in Cooperation with TU Wien and UNI Kaiser-slautern under the Task E 5/991 of the Fund for Science and Culture Development TU in Brno.

The principal mission of this research work was to widen the knowledge in the area of regional planning and to study and compare the present European status of this discipline, especially in the German speaking countries. The research hase shown substantial differences not only between German, Swiss and Austrian methods, but also between the methodology of their own provinces or cantons. The study of regional plans of the joint border areas of Germany and France, especially that of PAMINA, which was developed at the Kaiserslautern Universit}' and covers the German area of Pfalz - Baden - Wuertenberg and the French area of the Northern Alsace, produced completely new facts. Finally, the very different regional planning methods of the centralized Czech and the decentralized Lower Austrian approach were thoroughly analyzed and applied to the plan of the joint Czech-Austrian border regions. All the findings, together with the critical comments were summarized and defended at the end of 1992. Their application continued until the completion of the task in 1994.

Education was the second objective of the research. Ideally, each university should model in their curriculums the conditions and situations which will occur in the next five, ten or twenty years to prepare today's students to deal with them, and to apply this knowledge wisely in the future. One of these situations is the gradual integration of European countries and their cooperation specifically in the planning of the border regions. Until recently, the Eastern Europe border regions were separated from the west by a sharp line or "iron curtain". This was the reason for providing research analysis and proposals for the border region between Břeclav - Znojmo and Retz - Schrattenberg by the senior students and professors of the Faculty of Architecture ant the Faculty of Civil Engineering of TU Brno and TU Wien and UNI Kaiserslautern. During the three joint seminars held in both countries, it was the work of students which brought dynamic, optimistic, but also realistic aspects into the border region: "AHA" (Autonomia, Hospia, Artia) and "JIZMONOWEI" (JlZni MOrava, Nieder Oestcrreich, WEInviertel).Without the thorough involvement of the students it would have been impossible to provide a detailed research and to propose 9 alternatives for the future development.

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WORKSHOP 95 ARCHITECTURE, URBANISM Sc VISUAL ARTS

The third aspect of the project, which evolved during the research was a political one. The creation of a new border with Slovakia and the need for a dialog with Austria were the main factors, why the scientific board of TU Brno decided to include the project in its programme and fund it. It was also accepted by the TU Wien and by the representatives of the Lower Austrian Regional Government. Towards the end of 1993 Dr. Erhard Busck, the Austrian vicechancellor and the Minister of Science and Research personally endorsed the programme. He provided the means for the travailing exhibition, which will in the years 1995-96 inform the citizens of both countries about the plans for the joint rural tourism, based on the existing cultural, natural and recreational wealth of the region while enjoying the local food and wine.

The fourth, totally unexpected contribution of the research was the discovery of the philosophy of the borders. Not only the political borders between the sovereign states, but also the borders between different life styles in general. Both during the investigations and input by schools and universities and also during the ongoing philosophical debates about the substance of our task it was found that the preferred category of separation was not a rigid line, but rather an area and space of transitional shape, characterized by continuous engagement and merger. These transitional borders can also be seen between the natural ecosystems, they support the political, cultural and economic prosperity of Swiss, and are reminiscence of the former Liechtenstein domain in the Moravian - Austrian region.

The research contributed to enrichment of the knowledge of participants in the field of both rational and emotional values.

References: [1] AKADEMIE FUER RAUMFORSCIWNG UND LANDESPLANUNG: Aspekte der

Raumenlwicklung und Raumlanung in der Tschcchoslowakei vnd in der Bundesrepublik Deulchland. Verlag der ALR, Hannover 1992.

[2] JANSEN, P. G. - RIETMANN, E.: Grcnzueberschreitendc Ziclc Jiter Wasserwitschaft, Natur und Ladschaft. Verlag des ILS, Dortmund 1989.

[3] OESTERREICHISCIIES RAUMORDNUNGS KONFERENZ: Offene Grenzcn - Neue Aufgabcn fuer die Regionalpolilik. Eigenvcrlag, VVicn 1991.

[4] KISTENMACHER, H.: Vergleich der Zentraloertlichen Systéme BRD - CFSR. Werk-stattbericht Nr.21, Kaiserslautern 1992.

[5] MICHNA, M. - a kol.: Návrh programu hospodářského a sociálního rozvoje okresu Břeclav. VÚROM, Brno 1992.

[6] GALVASOVÁ, I. - a kol.: Regionáhí aspekty rozvoje JM příhraničí ve vztahu к podmínkám rozvoje Brněnského regionu a Dolního Rakouska. VÚROM, Brno 1992.

This research has been conducted at the Faculty of Architecture and at the Faculty of Civil Engineering as part of the research project "Regional Plan of Conception of the Integration of South Moravian (the Czech Republic) and Lower Austrian (Austria) Border Regions" and has been supported by TU Brno grant No. E5/991.

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WORKSHOP % ЛНСШТИСТШШ, UHBANISM к VISUAL ARTS

PROJECT HANDICAP J. Siudlnr, J, Halabala, P, Hcr/nnova, P. Zalmanová

Faculty of Architecture VUT Brno, Dcpt, of Interior and Design Poříčí 5, 039 00 Hrno

Key words: architecture, handicap, architectural barriers, compensating aids, environment, school

Project HANDICAP is supposed to help on solving at least some problems in the field of total Integration of people who have problems with their environment with which they have to interact, The matter then is how to create an environment without barriers both psychological and particularly physical /not only the so-called architectural barriers/, In this field naturally belongs the whole system of the production of equipment, aids etc, including household goods compensating for the so-called handicap.

The programme of the research is altered by the state of the knowledge wc have of the given problems, In the present phase of the work wc try to prove the reality of the analytically evaluated experience and what wc know about the cability of society and of the individual to perceive and respond to this way of life imposed on him by circumstances, generally named "handicap",

One of the aims of our project is to find a way how to overcome barriers, architectural ones in particular, which make impossible or merely complicated life for the people who often get into complicated situations because for various reasons they are excluded from the dynamics of life. /We use the term HANDICAP as a general term - expressing the whole set of problems, for the definition of the term is very flexible./

The way wc chose for reaching our aims seems to be very unconventional, It is because wc built a real workplace where wc can almost immediately try out our ideas, suggestions, solutions etc, It involves particularly layouts, vertical and horizontal communication, corridors and lifts, compensating aids, furniture, design of household goods etc.

The school for PHY(Pliysically Hamlicapcd Youth) GEMINI at И Vaculíkova str. in Brno-Lcsna became our workplace. The method used in this institution is called "Reversed Integration". It is based on the idea derived from analytical research of the so-called integration applied not only in this country.

Information acquired from institutions of similar character in this country and abroad (Austria, Switzerland, England, France etc.) allowed us to define our problem. It means that the present state of readiness of both society and individuals to accept so-called handicapcd fellow-citizens into "their lifes" brings new almost stress situations which cannot be resolved. The integrations of handicapped children is still understood only formally. The problem is thus emphasized without in the suggesting any solution. The system of "Re-vcraed Integration" is based on the principal of gradual adaptation of handicapped people to their surroundings in a form which enables other people, relatively or temporally healthier, to enter their world and to perceive it as quite natural. That forms precious connections between two worlds existing separately before.

One part of project HANDICAP was to point out some other factors. Although they may seem unimportant, they can't be omitted as they influence the possible solution. Firstly it, is the attitude of society in their perception of these problems. Another important factor is the handicapped person's mental attitude.

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WORKSHOP 95 ARCHITECTURE, URBANISM fc VISUAL ARTS

Through evaluation of the results obtained during the work on the project we can explain more clearly the meaning of the word barrier and also humbleness. Thus we could try to influence the way people think.

Nowadays the project HANDICAP has gone beyond the original limits. Through the establishment of the school for PHY GEMINI has been living its own life.

Within the scope of the project HANDICAP several architectural designs of accessible objects, designs of household goods, furniture etc. /some of them were awarded prizes by Design Centrum CR/ were worked out as well as programmes of various public activities. We managed to establish contacts with similar workplaces here and abroad and last but not least we developed publishing activities, we work on TV films, radio programmes etc.

References: [1] BRZÁK, M. - NETSCHER, J.: Architektonické bariéry - jejich odstraňování. Praha

1989. [2] МАХА, M. - MIHULA, M. - SKOPEC, J. - ZAPLETALOVA, J.: Stavby bez bariér -

výstavba pro osoby se sníženou schopností pohybu. Praha 1992. [3] PÍSAŘÍK, J.: Handicap architektonické tvorby. Brno FA VUT, 1989. [4] STEINER, M. - A KOL: Přeprava osob se sníženou pohyblivostí. Zpráva к úkolu VÚD

1/82, Prah 1982. [5] Vyhláška S/v VTIR č.53/85 Sb. 0 obecných technických požadavcích užívání staveb

osobami s omezenou schopností pohybu. [6] Norm SN 521 500 mit Lcitfaden "BE1UNDERTEN GERECI1TES IUUEN". Schweiz-

erischer Invalidenverbend SIV, Olten, Schweiz 1989. [7] CODE OF PRACTISE FOR MEANS OF ESCAPE FOR DISABLED PEOPLE.

British Standarts Institute, BS 5588: Part 8, 1988. [8] STEMHORN, A.: Bauen fur Bchindcrte xtnd Belagte. Alexander Koch, Stuttgart,

1974. [9] RASCHKO, В. В.: Housing Interiors for the Disabled and Elderly. Van Nostrand

Reinhold Company Inc. New York, 1982.

This research has been supported by TU grant No. 991 E-6.

788

WORKSHOP 95 ARCHITECTURE, UllBANISM к VISUAL ARTS

INTENSIFICATION OF URBAN NETWORKS P. Srytr and coworkers

CTU, Fac. of Civil Eng., Dcpt. of Sanitary Engineering Thákurova 7, 1G6 29 Praha б

Key words: intensification, management, cfficicnty, reconstruction, urban networks

This is a brief overview of extensive research which was conducted in parts and was coordinated. The first step of the research was designing a set of bricks of a mobile duct (see Fig. 1).

P l g . 1

This solution was developed for the transformation period of urban networks and most emergency situations of urban networks.

789

WORKSHOP 95 ARCHITECTURE, UllDANISM fc VISUAL ARTS

In the second part of the rcsarcli the problems of intensification of water supply systems were solved using the Universal Block Duct (UBD). They were examined on different locality (parts of Ccskc Budějovice town) by using simulation methods (sec Fig, 2),

Fig.2

References: [1] SRYTR, P. - MACEK, L.: Contribution to the intensification of the operation of the

water supply system. Proč. Conf. STU, 1989, p. 71 - 81 [2] SRYTR, P. - and all: Intensification of the water supply system. CTU, Technical Paper,

Faculty of Civil Engineering, Prague, 1993, p. 61 - 71 [3] SRYTR, P. - REJTHAR, V. - SLADKOVSKÝ, J.: A Set of Briks of a Mobile Duct.

DW, Prague, 1994

This research has been conducted at the Department of Sanitary Engineering as part of the research project "Intensification of Urban Network" and lias been supported by TU grant No. 2070.

790

WORKSHOP % ARCHITECTURE, UHBANISM fc VISUAL ARTS

THE NEW USAGE OF MINING OBJECTS IN THE OSTRAVA-KARVINA

AGGLOMERATION

M. Matej

Institute of Monuments Heritage in Ostrava,, Korejská 12, Ostrava-Privoz, 702 00

Key words: mining objects, inhibition programme, Ostrava-Karvina agglomeration, new usage, old plants, rcstructuralization of industry, cultural industrial heritage, city-planning dominant, architectural composition, technological link-up, the totality of the surroundings, the authenticity of the surroundings

Within the framework of restructuring the industry, the coal mines of the Ostrava region have become a special problem. The existing conception of inhibition programmes which is unfortunately oriented at the demolitions of objects can be seen as desolate and it does not respect the character and potential of the particular objects and grounds.

Examples from abroad but especially practical experience from this country offer new functional usage of the particular objects and grounds directly. In the past, following coal mines found a new and successful usage:

a) The coal mine "Josef - in 1893 after stopping of its operation a reconstruction of the shaft building and engine room into flats was made.

b) The coal mines "Hugo" and "Elizabet" - represent a vast complex where the operation was stopped in the 50s of this century. The objects including pit buildings were used for storage purposes and supplementary production.

New usage of mining objects and grounds is possible in a wide range of activities from purely museum purposes to economic usage (production, storage) including the combination of these. The main part of the new usage cannot be seen - in spite of its unquestionable uniqueness - in exclusively converting them into museums (for example - the coal mine "Michal").

From the typological viewpoint mining grounds can be divided into the particular specific objects. From the point of view of the new functional usage we can roughly distinguish between the two following groups:

a) objects which are not functionally interchangeable (mining tower, equipped engine rooms etc.)

b) objects which are functionally interchangeable or which are not connected with the original mining operation (administration buildings, showers and toilets, workshops, storerooms etc.).

The most important criterion in evalutating the general industrial potential is its cultural value as it is analysed in the theory of industrial archeology. On the basis of experience in preserving industrial heritage in, for instance, England, Germany and France, and on a theoretical model presented at a Summer School of Industrial Archeology in Austria, it is possible to propose these principles of the industrial heritage preservation in the Ostrava -Karviná region:

791

WORKSHOP 95 ARCHITECTURE, URBAN1SM fc VISUAL ARTS

a) city-planning dominant - importance from the point of view of the picture of the town (mining tower, conical pit heaps - e.g. ".láma Hlubina", "Jáma Terezie").

b) overall architectural composition - respecting the principles of composition (e.g. "Jáma Alexandr" - the principle of honorary courtyard)

c) technological link-up - preserving the logical principles of operation, steam engine - boiler house and chimney (the heart of the plant), engine room and mining machines, mining tower and pit building

d) the totality and authenticity of the surroundings - preserving details, the original traces of operation etc.

e) preserving the essence and character of the particular objects - halls, views into an open roof truss, large-surface industrial windows, monitor tops etc.

According to the inventory that is still being taken at the moment, we may already form following general conclusions and summarise the preconditions for making new use of the buildings:

a) the objects of engine rooms, mechanical workshops are of free hall disposition, equipped with crane tracks and direct connection with railway and road network

b) production objects have the necessary background of administration buildings, changing rooms and showers and toilets.

c) what is also important is the background of the work force potential by means of the existing transport connection or the direct contact of workers colonies.

With regard to the restructuralization in progress wc recommend: a) to condition the approval of technical plans of liquidation by carrying out the docu

mentation of the building fund and by evaluating the industrial heritage. b) in case of cultural sights the means intended for the liquidation of objects should be

used for their reconstruction (see the Law No. 22/87 Dg.). c) in case of cultural sights to establish exceptions in fire, sanitary, electrotechnical and

other norms as a precondition for preserving the essence of industrial heritage during the new utilization of the objects (housing and public utilities), or possibly to standardize the European Community regulations in the Czech Republic so that foreign technical examples, which are at present obstructed by the existing system of norms and its reverse hierarchy of values, could be applied.

References: [1] ANTOŠOVA, D.: Památky výroby, védy a techniky. In: Industrials architcktura-

nevyuzitc dědictví. NTP Praha, 1990, sir. 25-30 [2] EBERT, W.: Landschaflspark Duisburg-Nord. Induslriegcscliichtler Fu"lirer. Edel-

Druck.Duisburg 1991 [3] EBERT, W.: Landschaftspnrk Duisburg-Nord. Bin Projekt im llahmen der Inlerna-

tionalen Bauausslellung Emscher Park. WAZ-DRUCK.DUISBURG 1992. [4] FRACNER, В.: Tri kroky к industrially architektuře. In: Industrialni architektura

nevyužité dědictví. NTP Praha, 1990, str. 18-24. [5] MENGE, M.: Industrialisierung durch die Landwirlschajt. In: Industricarchaolgische

Erkundungen. Berichte 13, Hildesheim 1983. [6] PAULINYI, A.: Industriearchdologie. Ncue Aspekte der Wirtschafts und Tech-

nikgeschichle. Dortmund 1975 [7] RAISTR1CK, A.: industrial Archaeology. Granada publishing 1979

792


EDUCATION OF PLANNING PROFESSIONALS K. Maier, K. VIcek, P . Rohon*,

J. Riha*, J. Štipek

CTU, Fac. of Architecture, Dcpt. of Urban Planning I Thákurova 7, 166 34 Praha 6

*CTU, Fac. of Civil Eng., Dept. of Irrigation & Drainage Thákurova 7, 166 29 Praha 6

Key words: education, planning, environment, geographic information systems (G1S)

The objective of the 1994 stage of the project was to establish and launch two new courses within the framework of the Spatial Planning Programme:

Housing and Housing Policy The issue of housing in the Czech Republic remains as one of the problems deeply rooted

in the previous central planning system. After dramatic social and political changes in the country, new housing construction dropped down to a fraction of previous, state-subsidized numbers. The poor maintenance of existing housing stock has not changed yet, due to regulated rents which cannot cover even the running costs. Municipalities became owners of most of the housing stock in systemic block of flats built in housing estates of the 1960s, 1970s and 1980s. They started the process of their privatization, with many risks not quite taken into consideration.

This situation makes the need of housing experts very urgent. Therefore, two tracks for education these experts were followed:

a) regular courses within the graduate curriculum of Architecture and Spatial Planning b) as a topic of the intensive retraining and refreshment course for practicizing planners,

professionals in self-governments of municipalities and local governments. Experts from Ministry of Economic Development, the Research Institute for Building

and Architecture, the Institute for Regional Planning (Tcrplan) and Faculty of Civil Engineering participated in developing the coursework, and also in lecturing. For the retraining courses, experts from Heriot-Watt University, Edinburgh were made available by the support of the British Council. In both tracks, students were asked to work on practical assignments to seek for a feasible solutions of the particular housing problems of the particular sites and communities.

Geographic Information Systems (GIS) This course was developed as a specialized training superstructure which followes the

existing compulsory training course of CAD provided by a general curriculum of the Faculty of Architecture. The objectives of the GIS training have been scaled in several steps:

1. an entry information on SW and HW equipment in the practice of urban planning, and on available types and resources of data

2. systems of storage and usage of the data 3. individual assignment: interactive systems 4. GIS - analytic and conceptual programs; contacts and colaboration with users of GIS

793


5. individual, independent assignment: GIS-bascd evaluation of territorial impact of investment.

The first step of the scale is a matter of instruction in the existing course Computers in Planning, this course being the precondition for the newly-established GIS course. In order to reach the higher steps, the team joined the cooperation with UNICOM and INTERGRAPH companies, with Faculty of Civil Engineering and the Research Institute for Building and Architecture.

The restrictions of the grant prevented the team from developing fully equipped working place with a full-grade GIS technology and, thus, reduced the original idea of the course.

With introducing the courses as described, the graduate curriculum of Planning within the Faculty of Architecture reached its complete scope. The next step is to evaluate the existing curricula and to find a proper mechanism of joined study among the involved higher education facilities.

References: [1] MAIER, K.: Planning and an Education in Planning in the Czech Republic Journal of

Planning Education and Research 13/1994:263-269, Association of Collegiate Schools of Planning, USA

[2] MAIER, K.: Vychová urbanistu - planovatelu na pražské Fakultě architektury (Education of Planners at the Faculty of Architecture, Prague) Uzemni plánováni a urbanismus 5/1994. Ministry of Economic Development, Prague

[3] ROHON, P.: Výuka problematiky životního prostředí (Education on Environment) Faculty of Civil Engineering, CTU Prague

[4] ILINCEVOVA, I.: GIS v uzemním plánováni (GIS in Planning) Research Institute for Building and Architecture, Prague 1994

This research has been conducted at the Department of Urban Planning as part of the research project Education of (spatial) planning professionals and has been supported by CTU grant No. 8ЦЗ.

794

Section 16

RELIABILITY

WORKSHOP 95 RELIABILITY

STATISTICAL APPROACH TO MODEL UNCERTAINTIES

M. Holický, M. Vorlíček

CTU, Klokner Institute, Dcpi. of Structural Reliability Solinova 7, 166 OS Praha 6

Key words: model function, uncertainty, random sample, coefficient, fractile, estimate

A calculation model based on a physical or empirical relation between relevant variables may be, in the simplest case, written [1] as

where Y denotes the model outcome, 7 the factor of model uncertainties, /() the model function and A' the basic variable. If the model function / ( ) is complete and exact, then the outcome Y can be predicted without error and the factor of model uncertainties 7 equals unity. In most cases, however, the model will be incomplete and inexact and the factor of model uncertainties 7 may be then treated as a random variable.

Consider a random sample of 11 measurements resulting in two sets of .т,- and т/; values. Corresponding values 7,- of 7 follow from equation (1) as

7. = V, I /(*.) (2) where the set of 7; values may be treated as a random sample taken from the popu

lation of the random variable 7. Its parameters may be estimated using known statistical techniques assuming a certain type of distribution. A general three parameter distribution appears to be a suficicntly general theoretical model.

Let 7 and s7 denote the sample mean and standard deviation of 7,. Then the p-fractile 7P may be estimated using the following general formula [2,3]

Ъ = 7 + hsi (3) where kp denotes the coefficient of the appropriate statistical method. This coefficient

is generally dependent on the probability p, on the sample size u, on the assumed coefficient ofskewness a, on the confidence level A and, in the case of the Bayesian approach, on other relevant information.

Besides traditional methods to determine the coefficient kp the so called prediction method, recommended in the International Standards ISO [1, 3], is also used. From this the coefficint kp can be calculated as

*, = tP yjl/n + 1 (4) where tp denotes the p-fractile of the generalized ^-distribution dependent on the as

sumed coefficient ofskewness a [2]. Note that this estimation method gives almost identical results to the traditional methods using the confidence level A = 0,75.

An estimate yp of the outcome variable Y recommended in [1] follows from equation (1) using the appropriate p-fractile xp of the basic variable A' and the estimate fp of 7

797


VP = Ъ /(•*>) (5) It should be noted, that the fractile estimate yr оГ the outcome variable Y given by

equation (5) represents only an approximate solution to the problem. A theoretically correct approach should consider the model function f(X, 7), where the parameter 7 represent the model uncertainty and can be treated as one of the basic random variables [I]. Another inaccuracy is due to negligence of the mutual dependence between the factor of model uncertainties 7 and basic variable A'.

As an example consider a simple relation between the concrete cube strength A' and the compressive strength Y [<1] supplemented by the factor of model uncertainty 7

V = 7(0,77-0,001A')A' (6) Consider a sample of 10 experimental measurements described by couples ж,-, i/;, i =

1,2,... 10. Using equation (6) the corresponding values 7,- and the sample mean and standard deviation 7 = 1,026, s*, = 0,052 were determined. Taking into account previous experience an approximate value of the coefficient of skcwncsso = 1 , 0 was assumed. In accordance with the traditional method for the confidence level A = 0,75 the coefficient kp = —1,68 [5] and equation (3) gives

7o,os = 1,026 - 1 , 6 8 0,052 =0,939 (7) For the prediction method it follows from the tables given in [2], that /0,os = —1,50

and using equations (3) and (4) 70,05 = 0,944; obviously the difference between this and the previous estimate 7o,o5 = 0,939 is negligible.

More extensive applications of the presented statistical approach [2] show the practical feasibility of the described operational technique for determination of the model uncertainties. Further research should be focused on more general model functions and mutual dependence of the basic variables and appropriate parameters of model uncertainties.

References: [1] ISO 2394: General Principles on Reliability for Structures. ISO/TC9S/SC2/WG1,

1994. [2] HOLICKÝ, M. - VORLÍCEK, M.: Theory of statistical estimation for parameters of

structural materials and components (in Czech). Report of KI CTU Prague, 1994. [3] ISO/CD 12491: Statistical Methods for Quality Control of Building Materials and Com

ponents. 1SO/TC9S/SC2/WG3, 1994.

[4] CSN 73 1205: Concrete Structures. Basis for design. (Czech Standard). ÚNM Prague, 1980.

[5] VORLÍCEK, M.: Tables of non-central values for lot/normal distribution (in Czech). Report of KI CTU Prague, 1994.

This research has been conducted at the Department of Structural Reliability of the Klokncr Institute, CTU Prague as part of the research projed "Stalialical Theory for Quality Control of Structural Materials and Components" and has been supported by the Fund for Development of Universities, grant No. 0003.

79S


PROBABILITY BASED ASSESSMENT OF SERVICE LIFE

M. Holický

CTU, Klokner Institute, Dept. of Structural Reliability Solinova 7, 166 OS Praha б

Key words: deterioration, reliability margin, damage level, probability, service life

Practical experience and theoretical investigations show [1] that the transition of deteriorating structures from a satisfactory to an unsatisfactory condition is gradual rather than abrupt. The damage level of these structures generally increases with increasing load ciTects including environmental impacts. This imprecision in definition of appropriate limit states may cause serious differences in the assessment of structural conditions. In a recent investigation of structural serviceability [2,3] the demand D(t) was considered as a classical random variable, while structural capacity C(t) was assumed to involve both randomness and fuzziness. In the following analysis of deteriorating structures previous concepts are generalized using the basic idea [4,5], that the damage level v{g{L)) £< 0,1 > is a function of the reliability margin g{t), defined as

g(l) = C(t)-D(t) (1)

The conceivable tri-linear form of the function v(g(l)) used in previous investigations [2,3] is considered here. If the reliability margin is less than a certain lower limit </i, then the damage level v(g(l)) = 1 and the structure is considered as fully failed. If this margin is greater than a certain upper limit дг, then the damage level v{g{l)) = 0 and the structure is considered as fully satisfactory without any damage. Within the transition region < д\,дг > the damage level u{g(t)) decreases with an increasing reliability margin g(l) and entirely vanishes for margins greater than gi.

Generally, if the membership function is a single-valued function, the reliability margin given the damage level v is obtained as g{l/u) = v~x({g{t)) and the corresponding probability of failure p/(t\i/) as the integral

Р/(<И=/ M«,0d« (2) J-OO

where <f>g(u,t) denotes the probability density function of the reliability margin g(t), и being a generic point of the reliability indicator. The total fuzzy probability of failure f(t) is then defined [2,3] as the integral of all failure probabilities p/(t\u) weighted by the damage level и taken over the entire range of и from 0 to 1:

*/(0 = ^ j f " p/(<l") <i" (3) where N is a normalizing factor reducing 7r/(i) to the conventional interval < 0,1 >.

The expected service life t, of a structure can be determined from equation (3) as the time, at which the fuzzy probability of failure TT/(ÍS) reaches a specified value яу,о, say 10~4. This decisive value should be specified by a detailed investigation of the possible

799


failure consctjiicnccs or by optimization analysis related to the fuzzy probabilistic concept; an appropriate objective function should be expressed in terms of the damage level // and the fuzzy probability of failure л-/. One optimization technique, based on the demand for minimum total cost С = Co + Kj(t) Cj, where C'0 denotes the initial cost, C/ the cost due to the full failure, recently applied to analyze structural serviceability [2], could be also used to investigate deteriorating structures. If an optimization technique cannot be used (due to the lack of input data), then the fuzzy probability of failure 7r/(/,) should be related to the probability accepted for ultimate or serviceability limit states for which values within the range from 10"' to 5 . 102 arc generally considered, assuming a design life of 50 years.

A recent analysis of various concrete structures [4,5] shows, that the resulting service life is strongly dependent on the assumed location of the transition region that needs to be related to the given deterioration mechanisms. Another critical point of the presented analysis is the choice of the relevant probability level required for compliance with performance requirements.

It appears, however, that the time dependent fuzzy probability of failure, which may be considered as a generalization of the traditionally defined probability of failure, can effectively be applied as a reliability measure of the deterioration in structures. The fuzzy probability of failure can be greater or less than the traditionally defined probability of failure depending on the specified membership function and on the position of the transition region, where a structure gradually loses its ability to comply with the imposed requirements; whenever specified requirements are significantly imprecise, the fuzziness of limit states should be always considered. The expected service life of concrete structures can be derived from the fuzzy probability of failure by specifying the appropriate membership function, its position and the desired probability level.

Further research into a probabilistic approach to the analysis of deteriorating structures should be primarily focusscd on the required level of failure probability and the theoretical models for the membership function, making allowance for the interaction of various deterioration mechanisms; relevant experimental data is urgently needed.

References: [1] SOMERVILLE, G.: Residual Service Life of Concrete Structures. In: IABSE Collo

quium on Remaining Structural Capacity, Copenhagen 19S3, pp. 29-36. [2] HOLICKÝ, M. - Óstlund, L.: Probabilistic Design. In: 1ABSE International Collo

quium on Structural Serviceability of Building, Goteborg 1993, pp. 91-98.

[3] HOLICKY, M.: Fuzzy Optimization of Structural Reliability. In: International Conference on Structural Reliability, ICOSSAR, Innsbruck 1993, pp. 1379-1382.

[4] HOLICKÝ, M. - HOLICKÁ, N. - KOLÍSKO, J.: Probabilily Based Assessment of Environmental Impacts. In: The Centenary Year Bridge Conference, Cardiff 1994, pp. 271-276.

[5] HOLICKY, M.: Uncertainties in Reliability of Deteriorating Structures. In: Australasian Structural Engineering Conference, Sydney 1994, pp. 1101-1106.

This research has been conducted at the Department of Structural Reliability, CTU Prague, as part of the research project "Environmental effects on the long time reliability of concrete structures" and has been supported by CTU grant No. 8219.

800


ADVANCED METHODS IN DRAFTING STRUCTURAL CODES

A. Florian

TU Brno, Faculty of Civil Engineering, Dcpt. of Structural Mechanics Veveří 95, 602 00 Brno

Key words: code drafting, reliability, safety, statistical analysis, Eurocodes, partial reliability coefficients, simulation techniques

Engineering reliability methods have been developed to assist in making design decisions in the presence of uncertainties of different kind. Evaluating the development of the reliability theory of civil engineering structures and the relating structural codes, the "limit-state method" (or the "partial reliability coefficient method") is utilized almost in all European countries, see e.g. the Czechoslovak structural codes (CSN Standards) or Eurocodes. The safety of structures is included in the structural codes by using partial reliability coefficients (PRCs). Generally, the PRCs should be calibrated to ensure that a prescribed level of reliability is achieved with the proposed code equation. Until now, the PRCs are not calibrated but are still based only on empirical knowledge and improvisation or on re-evaluation of existing structures.

In the project, the methodology of the possible application of modern simulation techniques for calibrating the PRCs to the desired reliability level measured by reliability index /9 is described. Here, we emphasize tiie possibility of simulation techniques to supplement or even replace the experimental research and thus to accelerate data collection needed for further evaluation of PRCs. It is also emphasized that different sources of uncertainties, e.g. inherent randomness in material properties, loading, geometry, etc., or imperfect modeling, or gross errors can be taken into account by using simulation techniques. The proposed calibration process has the following desirable features:

1. It is fully compatible with the theoretical and methodological background of the "partial reliability coefficient method" used for example in Eurocodes.

2. It is based on utilizing simulation techniques. 3. The format is quite general and thus it should be used for different types of PRCs

acting in the resistance or the loading side of the code equation. '1. The desired reliability level defined by the appropriate design (target) value of

reliability index is achieved with a relatively high accuracy. The proposed methodology is verified by an example. A large parametric study has

been performed in which the reliability of resistance of rectangular concrete cross-sections of different dimensions and with a different amount of reinforcement steel under pure bending is examined. The calculations arc performed for each possible combination of individual dimensions and the amount of steel by using (i) simulation technique taking into account the inherent randomness in different input variables, and by (ii) appropriate code equation with partial reliability coefficients set to their code values. The reliability index obtained from the individual calculations is compared with the desired design (target) value of reliability index taken from Eurocode 1. It is shown that the resistance of different cross-sections with different amount of steel has a different reliability level. The reliability index varies within interval 2.1 - 5.9 compared with the desired value 3.04. Thus, some cross-sections

801

WORKSHOP % RELIABILITY

designed by using code equation arc under-designed and others arc ovcr-dcsigncd as a result of non-existing calibration of PRCs in the code equation used.

It is suggested to utilize the proposed methodology to calibrate the resistance partial reliability coefficient. Performing the suggested methodology the values of calibrated coefficient will have to vary within interval 0.49 - 1.31 to achieve the reliability index as close as possible to the desired value of 3.04.

References: [1] DITLEVSEN, 0. : Fundamental Postulate in Structural Safety. J. of. Eng. Mech,, 4,

pp. 1096-Í102, 1983 [2] FLORIAN, A. - SCHMID, P.: Reliability Analysis of Reinforced Cross-Sections. Build

ing Res. J., 2, pp. 133-147, 1993 [3] FLORIAN, A.: PouSití pokročilých metod pro tvorbu nové generace norem pro

navrhováni konstrukcí. Research Rep., Faculty of Civil Eng., TU Brno, grant No. 30/93-D, 1993

[4] MAREK, P.: Blíží se kvalitativní změny norem pro posuzování spolehlivosti ocelových konstrukcí? Poz. stavby, 2, pp. 55-57, 198S

[5] ROSENBLUETH, E.: Towards Optimum Design Through Building Codes. J. of the Struct. Div., 3, pp. 591-607, 1976

[6] TICHÝ, M.: Pravděpodobnostní optimalizace dimenzování stavebních konstrukcí. Academia Praha, 1986

This research has been conducted at the Department of Structural Mechanics, Faculty of Civil Engineering, TU Brno as part of the research project "Advanced Methods in Drafting Structural Codes" and has been supported by TU grant No. 30/93-D

802


AMENDMENT OF THE ČSN 73 6209 LOADING TESTS OF BRIDGES

M. Studničková

CTU, Klokner Institute, Dept. of Engineering Mechanics Solinova 7, 16G OS Praha 6

Key words: bridge, testing, static and dynamic loading, footbridge, highway bridge, vibration, response

The first, issue of CSN 73 6209 - Loading Tests of Bridges appeared in 19CS. In the course of the existence of the standard the assessment of bridges as well as the technology of bridge construction have undergone such development as has changed entirely the purpose of loading tests. While previously the loading tests checked the static and the dynamic functions of the bridge and the quality of the work, at present the quality control is based on a much broader system of quality assurance.

Recently the loading tests of bridges are used, as a rule, to verify and specify in more accurate terms the analytical model and to ascertain the static and dynamic parameters of bridges erected by new technologies, from new materials, and of unusual structural systems.

The greatest problems in the application of the standard arose in the assessment of dynamic loading tests of prcstresscd concrete box girder highway bridges which often did not satisfy the criteria of the standard [2], although they were erected evidently in a proper way and in accordance with the design. The discrepancies between the provisions of the standard and the icsults of dynamic tests have made it necessary to check all available facts and information concerning the problem. Detailed investigations, the results of which are summed up in [l], have revealed that the procedure prescribed by the standard [2) is not correct and that the cvfduation of the test according to [2] may yield entirely misleading results,

A new proposal for the principal assessment criterion of the dynamic test is the comparison of its results with a dynamic analysis of the bridge structure elaborated with reference to the method of dynamic testing and dynamic loading used. In the first place comparisons between the computed values and the test results of the following quantities will be made:

a) natural frequencies, b) natural vibration modes, c) vibration damping, (I) amplitudes of forced vibrations in a sufficient number of selected points in the structure.

Because of the vibration problems caused by pedestrians in slender footbridges, a serviceability criterion has been introduced. If the lowest natural frequency of the footbridge vibration is in the vertical direction within the interval of l.C - 2.<1 Hz or less than 5 Hz, excessive vibrations of the footbridge arc produced by the pedestrians, as a rule. The amended standard introduces a serviceability criterion specified in the international standard ISO 10 137 which introduces the permissible level of vibration acceleration with reference to their effect on the human being.

803


As long as the measured peak values of vibration acceleration due to simulated footbridge traffic exceed the values given by the line in Fig. 1, the vibrations arc excessive and it is probable that the pedestrians will complain of excessive "liveliness" of the footbridge.

Й [ms-2] о

2 0.96 < | 0.60 P 0.50 < 0.38 ы у 0.24 о <

0.5 1.0 1.6 2.5 4.0 6.3 10 16 25 f[Hz]

Fig. 1: Proposed acceleration limits for walking vibrations

For the purpose of dynamic tests the pedestrian traffic on the footbridge is simulated in two ways:

1) Random passages of pedestrians along the footbridge at the level of the assumed traffic intensity (number of pedestrians per time unit).

2) Coordinated walk of two pedestrians in resonance with the lowest natural frequency in vertical bending fk=fo or in resonance with some higher natural frequency fk=fi or walking at a pace with a frequency of / i= / 0 / 2 or 2/a .

Amendment of the standard was brought about after the continuing disharmony between the results of dynamic loading tests and the dynamic coefficient specified by the loading standard. A new act on technical standards No. 142/1991 CoL has also entered into operation and the European standards (Eurocodes) are being introduced gradually into our standardization practice. It was necessary to harmonize all these regulations to ensure that they contain no mutually contradictory provisions. For instance, the European standard ENV-1991-3 does not introduce the dynamic coefficient for highway bridges; therefore, we cannot verify it by dynamic tests.

References:

[1] STUDNICKOVÁ, M.: Dynamic assessment of highway bridges according to Czechoslovak standards (in Czech), Inženýrské stavby, No. 10, 1992.

[2] CSN 73 6209 Loading tests of bridges (1979)+Amendment a-6/1990.

[3] ISO 10137 Serviceability of Buildings against Vibrations (1982).

This research has been conducted at the Department of Mechanics as part of the research project "Modelling of Structural Systems and Dynamics Loads" and has been supported by CTU grant No. 8Ц7.

/ / r —

/ /

804


RELIABILITY-BASED DESIGN OF COMPOSITES

A. Feraidon, J. Šejnoha

CTU, Fac. of Civil Eng., Dept. of Structural Mechanics Thákurova 7, 166 29 Praha 6

Key words: probability, fiber angle, volume content, stiffness, lamination parameters

The strength and stiffness of composite plates depend on the phase volume fractions, orientations of reinforcing bars, and stacking sequences. Many stiffness-based studies have been carried out jn order to obtain the optimum fiber angles for the maximum stiffness, the maximum buckling strength, and the fundamental frequency. Those studies assume deterministic conditions where the material parameters and applied loading have no random variations. However, the optimum fiber angles obtained under probabilistic conditions differ markedly from the deterministic solutions. The reliability-based design is a suitable combination of probability analysis and optimization method.

1. Probabilistic studies on the reliability of the strength of fibrous composites can be broadly classified into two major categories: 1) Theoretical analysis of the variation of strength using micromcchanical models [1], and 2) Reliability analysis of the strength of laminated composites using a macroscopic failure [2]. In both approaches, the corresponding limit state function is a function of n basic random variables affecting the failure and can be expressed as:

М(Х)=^.(А'„А'2,..,А'„) A; = l,2,...m, (1)

where M is the safety margin. The failure probability of a structure can be obtained using the joint probability density function as

Я / = / /х(Х)ЛХ, <l% = dX,dX2...dXn • (2) JD

where D is the failure domain satisfying M < 0. The integration of eq. (2) in a multi-dimensional space is difficult. Consequently,

a reliability analysis is carried out by means of methods using a statistical approach or methods using a nonstatistical approach. Simulation, involving sampling and estimation (e.g. the MC method, importance sampling, adaptive sampling etc.), is the most prevalent statistical approach. Iterative methods using the first and second order moments of the safety margin M and the reliability (safety) index 0 should be pointed out among numerous nonstatistical approaches.When the safety margin is nonlinear, the base random vector X is transformed into the independent standard normal vector U and the reliability index /3 = min(u*Tu*)1/'2 is obtained following Hasofer and Lind as the shortest distance between the point u* on the failure surface h[u) = M(\) = 0 and the origin in U space. Once the design point u* has been found, the failure probability can be estimated as Pj = ф(—/3) and the reliability function R = 1 — Pj = ф{0). 2. The in-plane and flextural stiffness of symmetric and orthotopic laminated composites become the functions of the lamination parameters V,*, V2*, И7,*, W%, where (see[3])

805


2 rh/2 2 rh/2

V,' = r / cos20dz, V? = г / . coa4We (3) 1 h Jo h Jo i arc the in-plane parameters, whilst VVj", 1V2" are the flcxural parameters, // being thickness cť a laminate and 0 - the fiber angle that varies along the thickness according to the stacking of a laminate. The lamination parameters arc suitable especially for the following stifiness-based design: ;

Optimize f{V{,Vhw'\*wi) subject to

P[</ , (A*,DV0>0]>P o , (4)

where A",D" arc the respective normalized in-plane and flcxural stiffnesses, P0 is the prescribed lower bound of probability.Thc objective function may be any function of the stacking sequence and volume fractions of a laminate.

As an illustrative example that can be solved analytically let us consider a one dimensional random base vector X = A'i(/(x, = 0.3,cr»,//ir, = 0.2) and a simple constraint fli(A'i) = 10 - e\ = K2 - a2(V,*, Ц", ВД, where a = (hA[)-\K = 5 * 10"3.The relation between the reliability function R = 1 - /'/ and the lamination parameters Vj", Ц" is depicted in Fig.l. The contour curves with a constant reliability level Я = const, specify the domains in which the points (Ц", Vj") satisfy the probability constraints formulated by (4)

Fig. 1: Reliability as a function of lamination parameters

References: [1] DVORAK, G. J. - SEJNOHA, M.: Initial failure maps for ceramic and melal matrix

composite laminates in : Europe-US Workshop on Fracture and Damage in Quasihritllc Structures, part nine Prague 1994, pp. 575-588.

[2] MIKI, M. - MUROTSU, Y. - TANAKA, T. - SHAO, S.: Reliability of Unidirectional Fibrous Composites . AIAA Journal , Vol. 28, No. 11, 1990, pp. 1980-1986.

[3] MIKI, M. - MUROTSU, Y. - MUROYAMA, N. - TANAKA, Т.: Application of Lamination Parameters to Reliability-Based Stiffness Design of Composites. AIAA .Journal, Vol. 31, No. 10 ,1993, pp. I93S-1945.

This research has been conducted at the Department of Structural Mechanics, Faculty of Civil Engineering as a part of the research project "Fuzzy-probabilistic concept of lime dependent structural reliability" and has been supported by GACll grant No. 103/9^/0131.

S06


THE EFFECTS OF PERFORATIONS IN CLAY UNITS ON

MASONRY STRENGTH D. Pume

CTU, Klokncr Institute, Dept. of Reliability Solinova 7, 166 OS Praha 6

Key words: masonry, clay masonry units, compressive strength, masonry bond

Masonry is a composite material made with masonry units and mortar joints, both vertical and horizontal. Crack development and consequently, the compressive resistance of masonry, depends on the coring pattern of the vertically perforated units. The planes of vertical cracks in the masonry wall are caused by the vertically perforated clay units parallel to the wall faces. Several theoretical solutions to the problem have been presented [I, 2].

Clay units and mortar in the bed joints of a masonry wall under compression arc horizontally extending, perpcndiculary to the wall's forces. The Poisson ratios for both materials arc different. If no bond existed between the contact plane units and the mortar, than the horizontal strain of the mortar would be greater than that of the units. However a bond docs exist. The horizontal strains of both materials arc identical. The masonry units are under vertical compression and in horizontal tension. The mortar joints arc under both vertical and horizontal compression.

The stress states relevant to the failure of masonry units under "compression - tension" are given by the failure curve Фи connecting the points Л and В (Fig. la). The point Л [cIU = 0, (Tyu = /uc] expresses the failure of the unit under uniaxial vertical compression, the point В [ffj.,, = Jut, avu = 0] corresponds to the uniaxial horizontal tensile failure of the unit. The curve Ф„ should be determined experimentally. The point С expresses the uniaxial compressive strength fmc of the mortar in the bed joint. The failure curve Ф т of the mortar under "compression - compression" is usually considered as linear. It is also determined by tests. The coordinates of the intersection point D [cxDi^yo] determine the stress state at which failure of the unit occurs.

The theoretical approach has been confirmed by the failure mode of the many small masonry walls that have been tested using the vertically perforated clay units [3].

If the horizontal tensile strength of the unit is decreased, mostly by extending the area of vertical cores (it occurs in praxis very frequently), the horizontal tensile strengths of the units decrease proportionally. Since the failure curves Ф„ and Ф,„, proposed by several authors, have been estimated on separate specimens (units, mortar prisms), not on masonry itself, it is necessary to support the theoretical solution by the experimental results. According to our analysis, the decrease of masonry compressive strength is proportionate to the decrease in the horizontal tensile strength of the units, but deviations of up to ±20% are to be expected.

Let us consider a masonry wall in a stretcher bond (ST) with vertically perforated clay units (Fig. lb). The effective area Aw,e/ of the unit is approx. equal to 0.5 - multiple of the total section area Aw. When the masonry wall is erected in the header bond (IID) with the same units, the effective area Av,ej is equal only to 0.37 - multiple of A\> (Fig. lc).

807


We introduce the ratios Kcp = (Ау,е/ xA\v)/(A\V,ej * Av) and h'/iofsr = ft,i,Hn/fut,ST, where ft,t,HD (ftit,sr) is the experimentally estimated compressive strength of the masonry in the header (stretcher) bond.

The experimentally estimated relationships Kcp — KIID/ST f°r masonry with clay units CDK 32 (321 x 235 x 148 mm), CDK 3613 (364 x 237 x 116 or 176 mm) and TYN 213 (2S5 x 189 X 213 mm) are shown in Fig. Id.

d)

1 HD

di--=-~ b'

1.0

0,9

ь08 1Л

J J 0.7 и ь V)

h * 0 . 6

I fM3 |oh b = 116mm I e h b = 176mm I

I /

M5<

I I /

i< /№

/ / /

oM3 JMI5

I M10

X / dM10

I I

AM9

I

/ / 0.5 I

CDK32| hh =116

\ i ' ICDK36B TYN

i _L i ihb ' " P 0.5 0.6 0.70,72 0.8 0,86 0,9

Kcp = ( A V , e f , A w ) / ( A 4 i f A v )

1,0

Fig. 1. The failure process of masonry a) failure lines Ф„ and Ф т , b) orientation of section W-W, c) orientation of section V-V, d) relationships Kcp - КЦО/ST

References: [1] PUME, D.: Effect of brick geometry on masonry strength, pp. 11-17. The International

Journal of Masonry Construction. 1980,1, [2] OHLER, A.: Zur Bcrechnring der Drtickfcsligkcil von Maucrwerk unter Berucksichti-

gung des mehrachsigen Spannungszustandcs in Stein mid Mortel. Bautcchnik 19SC/5, pp. 163-169.

[3] PUME, D.: Compressive strength of masonry made from Czech clay units produced between J 955 and 1992.Acta Polytcchnica,t994 [34j,3, pp. 19-36.

This research has been conducted al the Department of structural reliability of the Klokner Institute, CTU Prague as part of the research project "Statistical Theory for Quality Control of Structural Materials and Components" and has been supported by the Fund for Development of Universities, grant No. 0003.

808


ANALYSIS OF SEISMIC LOADING OF TANK T 1500 (NH3)

F. Čermák

CTU, Klokncr Institute, Dept. of Reliability Šolínova 7, 166 08 Praha 6

Key words: seismic loading, response of structures, finite element method

The basic principle of any seismic design is that the product should meet the owner's requirements, which may be reduced to just three criteria, i.e. - function, - cost, - reliability.

While the terms function and cost are simple in principle, reliability concerns various technical factors relating to serviceability and safety. The above three criteria are interrelated.

For analysis of two- or three-dimensional models of structures equivalent static forces, response spectra, model analysis, direct integrations and non-linear methods are used.

In this paper the dynamic analysis of tank T 1500 (NH3) under seismic loading is demonstrated. For analysis of a continuous elastic model the finite element method is used. The equivalent static forces are equivalent to seismic loading of steel structures and concrete pile foundation. In Fig. 1 the basic model and it's deformations are shown, in Fig. 2 there arc the deformations and the bending moment of pile. Figure 3 and 4 shows the mainstress of tank and cover.

Fig. 1: The model and its deformations Fig. 2: The deformations and model of pile

809


lZGLifctCt

Fig. 3: The main stress of tank NII3 Fig. 4: The main stress of cover

References:

[1] CERMAK, P.: Spolehlivost stavebních konstrukcí při seismickém zatížení KÚ CVUT, Praha 1989

[2] CERMAK, F.: Ecaluating the reliability of building structures with the seismic effects, Proceedings of Workshop II on Seismic Vulnerability and Risk Assessment Trieste 10-14 Dec. 1990, project SEISMED, UNDRO, Geneva 1991

[3] DOWRICK, D. J.: Earthquake Resistent Design, John Wiley and sons 1977 [4] POULAY, T. - BACHMAN, H. - MOSER, K.: Erbebenbemessung von Stahl-

betonkochbauten Birkhauser, Berlin 1990

This research has been conducted at the Department of Reliability of the Klokner Institute, CTU Prague as part of the research project "Statistical Theory for Quality Control of Structural Materials and Components'' and has been supported by the Fund for Development of Universities, grant No. 0003.

810


VERIFICATION OF BRIDGE RECONSTRUCTION

BY MEANS OF WIRE STRAIN GAUGES V. Hrdoušek, V. Kukaň, J. Záruba*

CTU, Рас. of Civil Eng., Dcpt. of Concrete Structures & Bridges Thákurova 7, 1G6 29 Praha б

*CTU, Klokner Institute, Dept. of Concrete & Masonry Structures Solinova 7, 166 08 Praha 6,

Key words: repair, strengthening, wire strain gauge,

In recent years several outstanding road bridges have been repaired and simultaneously strengthened to comply with the requirements of their managers. The requirements affected their higher loadability, because their original structures had been designed for live loads currently exceeded by standart traffic.

In most cases they are reinforced cocretc beam superstructures; their flange plate is strengthened by a concrete overlay. The longitudinal as well as transverse beams, possibly suspensions in case of archc bridges with suspended decks are reinforced with bars. For example with an IITP dia of 26 mm bars or external strands of the Lp 15,5 mm type.

The effectiveness of strengthening cannot be verified by a standard loading test in the course of which mostly only the deformations of decisive members are observed in the given moment. It is necessary to monitor the effect of strengthening at any time during traffic on the bridge deck without the necessity of another loading test; i.e. to these ensures of wether the assumptions of the strengthening design are being fulfilled on a long-term bases. This purpose should be achieved by means of a wire strain gauges previously developed in the Klokncr Institute of the Czech Technical University, an adequate mobile measuring apparatus.

The application of wire strain gauges on bridges in situ necessitates: - simple and reliable mechanical fastening; - sufficient accuracy and sensitivity. The sensitivity of 1 microstrain per 1 bit can be

attained without problems. It has been already proved by measurements that the wire strain gauges achieve a dispersal which equals 1/3 of the dispersal of equal measurements performed by resistance strain gauges. In the case of measurements on mechanically stable members we performed the measuring technique of prestrcssing the bars with an error less than 10 microstrains;

- resistance to side effects, such as temperature and moisture. Temperature differences between the structure and the wire may be prevented by edequate and efficient thermal insulation. Residual differences of the tcnnal expansivity between the steel of the measuring wire and the material of the measured structure are eliminated by a comparison with data of a compensation strain gauge. The elimination of thermal stresses due to an irregular warming of the structure must be Imsed on the theoretical model of the given structure; it is necessary to make a theoretical computation of these stresses and then confum the initial assumptions of the theoretical model by temperature measurements at selected points. Moisture does not distort the results because the wire strain gauge is a mechanical gauge

811

WORKSHOP 95 HHUAHIUTY

with data transmission in frequency form, The problem of volume changes of the measured structure with reference to moisture changes may be solved analogously with the solution of the temperature changes of the structure;

- reliability, which was verified on the Moravian Bridge in the town of Hradec Královo by the doubling of wire strain gauges and simultaneous measurements by means of resistance strain gauges. The mcastircnients concerned stress variations in the bars' strengthening cross beams during a static loading test, Long-term reliability results from the resistance of wire strain gauges against moisture lias been continuously proven by experience ammasscd in the course of experiments carried out in exacting conditions;

- durability of installed wire strain gaugcs.After their fastening to bais the strain gauges are provided with a protective coat preventing their mechanical damage (e.g, by plastering — see the Malsovice Bridge in Hradec Králové. The wire strain gauges do not require any other maintenance. The measuring system may be activated fit any time and itr. sensitivity constant remains preserved in its full extent, even if it, is necessary to rewire the cable connection;

- mobility, The funds of the grant were used for the manufacturing of a 1G channel apparatus for in situ measurements serving manual readings of mechanical stresses; the measured values are shown on a four digit display. The apparatus is ted from a built-in accumulator battery with the possibility of feeding and accumulator recharging from an external source.

References:

[1] HRDOUSEK, V. - BOHÁC, П.: Repair of the Concrete Bridge in Hradec Králové, pp. 382-386. Proceeding of the First Slovak Conference on Concrete Structures. Bratislava 1994

This research has been conducted at the Department of Concrete Structures and Bridges as part of the research project "Theoretical basis and checking methods of bridge reconstruction", and has been supported by the CTU grant No. 18150

812


SENSITIVITY AND PROBABILISTIC ANALYSES OF CHARLES BRIDGE

J . Žák, D. Novák*

TU Brno, Рас. of Civil Eng., Dept. of Concrete and Masonry Structures Údolní 53, 66237 Brno

*TU Brno, Fac. of Civil Eng., Dept. of Structural Mechanics Veveri 95, 66237 Brno

Key words: structural analysis, FEM models, ANSYS, temperature loads, statistical simulation, Latin Hypercube Sampling, sensitivity analysis, probability

The last reconstruction of the famous Charles bridge, the valuable historical monument of Prague, caused that the bridge changed its structural behaviour. The reinforced concrete slab without dilatation and anchors made the bridge too rigid. This resulted in excessive deflections and cracks.

The aim of the present study was to understand the structural behaviour of the bridge under temperature loads respecting the different materials and their interactions. Finite element package ANSYS was used for the temperature and structural analyses. Three different variants were prepared and analyzed corresponding to the slate of the bridge before the last reconstruction, the current state and the state after the proposed reconstruction. A statistical appioach was utilized to model material properties of the bridge that were considered as random variables. Their statistical characteristics were estimated and then used for statistical, sensitivity and probability analyses. The arch number IX. was selected for the analysis. Two cross-sections (on the top of the arch and the foot of the arch) were analyzed using 2D plane strain finite elements.

Three different load cases were considered in the analysis as a result of the study of meteorological data: 1/ warm top surface and the cold bottom surface, 2/ warm surface and the cold core, 3/ cold surface and the warm core. 2D temperature elements (PLANE55) were used to obtain the distribution of temperature field in the cross-section in the first step of the solution. The calculated temperatures were converted into initial strains and then transformed into an equivalent external load in the second step of the solution. The temperature elements were changed to the corresponding structural plane strain elements (PLANE42). The structural analysis was performed a hundred times for different realizations of input material properties within the framework of statistical simulation.

The bridge was built of sandstone, arenaceous marl, unknown materials and granite sett paving in sand. The current materials are sandstone, arenaceous marl, concrete slab anchored to the walls, keramzit concrete and granite sett paving in mortar. The proposed repair works comprise the removal of the concrete slab, dilatation gaps of keramzit concrete and granite sett paving in sand. Different materials were connected using special contact elements (C0NTAC12) which made possible to model friction, normal and tangential initial stiffness and possible gaps. The results of various tests and the study of theoretical values of material characteristics resulted in the estimation of their input values. Estimated ranges for the Young modulus and the coefficient of thermal expansion were the base for the estimation of statistical parameters of these random variables.

813


It was quite a difficult task to input correct coefficients of the thermal expansivity for the longitudinal direction and for the kcramzit with dilatation. Longitudinal strains arc zero for the plane strain analysis but the coefficient of the thermal expansion would produce unrealistic stresses in this direction. On the other hand zero value of the coefficient of thermal expansion would not be correct for this analysis. As a compromise the coefficient of thermal expansion for the longitudinal direction was estimated as 1/6 of the normal value, ft would also be difficult to model dilatations. We assumed that the strains perpendicular to the dilatations do not almost produce any stresses. So wc again assumed the value of the coefficient of the thermal expansion to be 1/6 of its normal value in this direction.

A powerful numerical simulation technique Latin Ifypercube Sampling in a combination of FEM package ANSYS with different realizations of input random variables were used a hundred times for each load case and each variant, together nine hundred single temperature/structural analyses. The aim was to obtain the scatter of stresses and deflections -to estimate their mean values and variances in selected nodes or elements and to use these results to evaluate the current state of the bridge and the proposed repair works.

As an additional result of simulation was obtained - a sensitivity analysis. This provided information about the importance of basic random variables. Dominating and non-dominating variables can be distinguished using sensitivity measures. Two different types of sensitivity were used: Sensitivity in the form of variation coefficients and nonparametric rank-order correlation coefficients. The probability that the structural response variable (stress or deflection) will be greater than the prescribed value was also calculated.

It should be noted that the present statistical simulation was based on the 2D model that cannot produce accurate comprehensive results for this type of structures. Significant differences were found comparing structural deterministic results on 2D and 3D models. 3D model should be used for more reliable results, but we realized that, bearing in mind contact elements, total number of elements and number of analyses, requirements on hardware and the time for the development of the model would exceed our facilities.

It was shown that more reliable results were obtained here by using the statistical approach rather than the classical deterministic analysis. These results might be beneficial for a better understanding of the structural behaviour and for the proposals of future reconstructions of Charles bridge.

References: [1] ANSYS: User's Manual, revision 5.0, Volumes I, II, III a IV, Swanson Analysis Sys

tems, Inc., Houston, 1994 [2] KRATOCHVÍLOVÁ, D.: Využití systému ANSYS pro analýzu vlivu teplotních změn

na konstrukci I\arlova mostu, diplomová práce, PAST VUT Brno, 1994 [3] NOVÁK, D. - TEPLÝ, B. - SHIP AISIII, N.: Sensitivity analysis of structures: A review

Proc. of 5th Int. Conf. on Civil Structural Engineering Computing CIVIL-COMP'93, pp. 201-207, Edinburgh, Scotland

This research has been conducted at the Department of Concrete and Masonry Structures as a part of the research project '"Sensitivity and Probabilistic Analysis of Charles Bridge" and lias been supported by Til Brno grant No. BlS/ůJ.

814


ASSESSMENT OF WALL PANEL BUILDINGS

F. Čermák, V. Moucha*, D. Pumě, S. Modrý, M. Eliášová, J. Chmel

CTU, Klokner Institute, Dcpt. of Reliability and Dcpt.of Concr. Technology Solinova 7, 1G6 08 Praha 6

*Moucha Consulting Office, Divadelní S2S 531 59 Pardubice

Key words: wall panel buildings, assessment

In 19S5, the majority of all new flats (75%) were constructed out of prefabricated concrete and designed as multistorey buildings by large state buildings firms.

Such prefabricated concrete buildings were designed as wall panel structures with load-bearing shear walls.

The designers and the contractors were forced by the state to improve the user's parameters of the buildings. Some good results have been achieved. Ridiculously, a decrease in self-weight was considered as an important achievement in these buildings.

Much less attention has been paid to the saving of energy in the detailing of the external walls (mantles) absemblcd from different wall panels. Unfortunately, the results of such irresponsibility, possibly the common approach in many parts of the world at that time, are appearing now in their full extent. Besides this, the durability period of some materials within the prefab mantles is expiring just at this present time.

In this research the building under consideration is a wall panel building with four floors above the groundlevel and with one floor in the basement. It was constructed between 19G2 and 196'1 as a typical KS HK 60 and 65, structure.

The external longitudinal walls were assembled from longitudinal parapet wall elements and rows of double-glazed windows.

The longitudinal parapet wall elements are reinforced along their four edges by 8 mm diameter bars and additionally by steel meshes 2.5/100 -2.5/100 close to the outer and inner surface. The "envelope" of the element is made from the reinforced concrete; inside, there are autoclaved aerated concrete masonry units.

In this particular case, the external surface of the parapet elements revealed many cracks.

That is the reason why these parapet elements were assessed very thoroughly in the laboratories of the Klokner institute.

The following data on the test specimens (londitudinal wall elements after having been transported from the building site to the laboratories) are given:

- overall dimensions, - dimensions of the grooves and recesses, - damage of the surface.

Load tests of parapet elements were also carried out. The elements were loaded gradually, without reloading.

A theoretical analysis was simultaneously carried out with the experimental load tests.

815


The influence of the environmental impact on the stale and possible deterioration of panels was also assessed.

This research has been conducted at h'lokner Institute as part of the research project "Assessment of Wall Panel Buildings" and has bees supportul by the Netherland Government Grant.

816

WORKSHOP % RELIABILITY

RESONANT PRESSURE SENSOR K. Draxler, F. Mazánek, J. Věříš

CTU, Fac. of Electrical Eng., Dept. of Measurements Technická 2, IGG 27 Praha C

Key words: pressure, sensor, measurement, resonance

General. The advantage of resonant pressure sensors is their high accuracy, negligible hysteresis and output signal suitable for direct processing in digital systems. Several designs of resonant pressure sensors arc described in [1-3].

In this article, the performance of the resonant pressure sensor developed by Mikrotechna Modřany s.r.o,, is discussed. The electronic circuity was designed and the performance measured by the Department of Measurement in the Faculty of Electrical Engineering, CTU.

Sensor and electronic circuity. The sensor is based on a vibrating thin-wall cylinder made from ferromagnetic material. The inner cavity of cylinder is exposed to measured pressure, while outside of the cylinder, a vacuum exist. The tensile stress in cylinder wall is a function of the loading pressure. Within the elastic limit, the cylinder resonant frequency, as it is a function of the tension, varies in relation to the pressure.

The cylinder is made to oscillate at its resonance point by employing two electromagnetic coils. A noise spike from wideband amplifier excites the first coil, and a magnetic field loads the cylinder impulsively, thereby inducing oscillation at the resonant frequency. The second coil senses the resulting motion, and produces a corresponding voltage. This, then, is amplified and fed back to the drive coil to sustain oscillation.

Performance. The characteristics of the sensor have been measured using a computer-controlled system (Fig. 1). Loading pressure is generated by pressure calibrators, the Druck DP1501 and DPI510. The sensor is placed inside the climatic chamber to determine a temperature coefficient. The temperature is derived by measuring voltage across a silicon diode.

The prototype sensor exhibited the characteristics shown in Fig. 2 and parameters listed in the following tabic.

Nominal pressure range: 0-600kPa (absolute pressure) Nominal frequency: 5500IIz (pressure=101kPa) Sensitivity: 3.2Hz/kPa Temperature coefficient: -l.SIlz/C Hysteresis: 60Pa

Through the use of computer linearization and temperature compensation, short-term accuracy better then lOOPa (0.017% FS) is achievable with this sensor.

817


CLIMATIC CHAMBER

THIN-HALL CYLINDER

-rw\ _£rvj f >

COMPUTER PC-AT

COUNTER _ RFT 62005 гЧ

AMPLIFIER

w Q T/U

TEMP-U0LTA6E TRANSDUCER

UOLTHETER HP 3110IA

PRESSURE CALIBRATOR DRUCK DPI501

DPI51О

HP-IB

Fig. 1: Performance measurement — schematic diagram FREQUENCY VS. PRESSURE

5400.00 -3

5200 00 i

5000.00 •

5300.00 •

5600.00

5W0.00

520000 :

5000.00 l i n n

temp=const

M I I I I 1 I I I I I I I I I I I I i I I I I I I I I 1 ' I I I I I 1 I I I I 1 I I I I I ' I I 1 I 0.00 £000 100 00 150.00 200 00 250.00 300.00 35000

pttPol

Fig. 2: Frequency vs. pressure plot

References:

[1] LANGDOM, R.: Resonant sensors — a review Journal of Physics and Electrotechnics: Scientific instruments, 18, 1985 p.103

[2] STEMME: Capacitively excited and detected resonant pressure sensor with temperature compensation Sensors and Actuators A: Physical v. 32, n. 1-3, 4/1992

[3] ĎAĎO, S.: Nekonvenční metody měření tlaku Sborník celostátní konference Měření tlaku 1992

This research has been conducted at the Department of Measurement as part of the research project and has not been supported.

818


C-V PROFILING ON HETEROJUNCTION SYSTEM

P . Sichrovský

CTU, Fac. of Electrical Eng., Dcpt. of Microelectronics Technická 2, 166 27 Praha 6

Key words: c-v profiling, hetcrojunction, quantum well

It is well known that C-V profiling through hclcrojunction (1IJ) or quantum well structure is a powerful and simple method of determining free-carrier distribution in a nonuniform semiconductor systems. In this paper several results of our measuring on n-N HJ system arc described. Wc have measured on GalnAs/ GalnAsP HJ by C-V profiling via the depletion method. Samples were grown by MBE on undoped N-type InP substrates and contain the stop GalnAsP layer and mainly HJ part including GalnAs quantum well (QW) and GalnAsP quantum barrier (QB). Widths of quantum wells, resp. barriers are less then 10 nm. At the top of the structure there is a measuring PN junction (PNJ) InP/GalnAsP. The distance between PNJ and HJ is approximately 90-100 nm. This is illustrated in Fig. 1.

1-2 /im(P)InP/Zn/

90 nm (N) GalnAsP /undoped/ : QW 5 nm Gain te + + QB 9 nm GalnAsP /undoped/

asi 100 nm GalnAsP (N) /undoped/

xO, 1 // m (max asi 0,2 fi m) InP IS/ (N)

subst. InP/S/(N)

Fig. 1: Cross section through the measured structure

The basis of free-carrier distribution determination is the measurement of C-V curves. In our case in order to obtain the capacitance data we have used a multi-frequency HP 4275A LCR analyser. All measurements were carried out at room temperature with constant frequency of 1 MHz and an applied voltage amplitude of 20 mV.

The above mentioned C-V profiling is a possible method of obtaining free-carrier distribution, in this case, where its apparent concentration is N,\pp(iv). The final equation, what we can get through general relationships, can be expressed as follows:

Г'л /ilV\~x

819


where

S (2)

and q is electron charge, 5 is the junction area, С is the capacitance, с is the material permitivity and V is the applied voltage. The apparent concentration of free-carrier distribution of HJ with QW and QB is shown in Fig. 2.

Fig. 2: Apparent concentration of HJ with QW and QB

The next important part concerning IIJ systems is the possibility of obtaining the magnitude of the built-in voltage Vrj. In this case we have to use the data from C-V curves again, and the magnitude of Vp can be obtained from the functioil 1/C2 vs. voltage, 1/C2 = / (V) , through the crossing point of the linear part of this curve with the voltage axis. If this part is not only linear, we can approximate it and get the Vp magnitude too.

References: [1] SUNDARAM, M. - GOSSARD, A. C: Capacitance-vollage profiling through graded

heterojunction: Theory and experiment.). Appl. Phys., 73(1), pp. 251-260, Jan. 1993. [2] FORREST, S. R. - SCHMIDT, P. H. - WILSON, R. B. - KAPLAN, M. L.: Measure

ment of the conduction band discontinuities of InGaAsP/JnP heterojunctions using capacitance-voltage analysis J. Vac. Sci. Technol., В 4(1), pp. 37-44, Jan/Feb 1986.

[3] KROEMER, H. - CHIEN, W.: On the theory of Debye averaging in the c-v profiling of semiconductors Solid-State Electronics, vol. 24, pp. 655-660, 1981.

This research has been conducted at the Department of Microelectronics as part of the research project "New organmetalic technology..." and has been supported by ASCR grant No. 1333069.

820


REINFORCED GRASS APPLICATION FOR EMERGENCY SPILLWAYS

L. Satrapa, V. Broza

CTU, Fac. of Civil Eng., Dept. of Hydrotcchnics Thákurova 7, 1G6 29 Praha G

Key words: dam safety, emergency spillway, reinforced grass, geotextile

Problem definition. The safety of a clam is greatly dependent on the appropriate design of an emergency spillway. Many dams (especially small dams and pond dikes) are not safe enough diie to the bad technical condition of the spillway, too small capacity of the emergency spillway, non existence of spillway etc.

Solution possibilities. The rehabilitation of an existing spillway or the construction of a new and suitable emergency spillway on an existing dam is always expensive and could be difficult from a technical and an environmental point of view. The advisable alternative to the technically difficult and expensive use of clasical technologies (concrete, stone) could be the application of reinforced grass. This technology is cheap, ecologically friendly and, if well designed, safe enough from the technical point of view.

Design criteria. A well designed and planted reinforced grass cover over an emergency spillway can withstand water flows with velocities up to 5m/s. Reinforced grass covers of emergency spillways are supposed to be applied mainly to small dams and pond dikes but the application for higher dams (15 m or more) is possible in some cases.

Application technology. The earth surface of the emergency spilway has to be smoothened and the stones and lumps of earth have to be removed. The surface is covered with a textile sandwich (grass seeds incorporated) or with durable textile or plastic netting (grass seeds spreaded manually). The revetment is joined to the subsoil with wooden pegs. The application of a thin earth layer (1-3 cm) on top of the textile sandwich or durable net is laborious but helps the grass plants to grow more successfully. The best season for the construction of the reinforced grass revetment is spring (March to May). In other seasons intensive irrigation for at least three weeks is necessary.

Operational experience. The reinforced grass cover was used for the construction of emergency spillways at two dry polders in Pelhřimov (South Bohemia). The first one was finished in May 1993, the second one in July 1993. The grass plants and the durable textile net created a very stiff and hard non erodable surface during its time of one year operation. No erosion processes are recognisable on the spillway surface. Some holes in the textile net are visible. It is necessary to continue observation of the named two emergency spillways to recognize the cause of these holes (bad grass maitenance, animals).

Conclusion. The application of reinforced grass could solve the problems with the safety of a large number of small dams in the Czech Republic. Other possibilities for reinforced grass application were found in the field of the construction of soil structures, nature protection, forest industry etc. Collaboration with other institutes has been started (Rudne doly Pribram, Silvaco Praha).

References: [1] Team: Design of Reinforced Ůrass Waterways CIRIA, Report 116, London, 1987

821


[2] VITEK, L. - HRABE, R: Grass for Water Structures Hydroprojekt Brno, 19S3 [3] BROZA, V. - SATRAPA, L.: New Trends in Dam Safety Evaluation New Requirements

for Structures and their Reliability, conference, Prag 1994 [4] SATRAPA, L.: Reinforced Grass Emergency Spillways for Small Dams Workshop 93 -

Environmental Engineering

7%is research has been conducted at the Department of Ilydrohchnology as part of the research project "Development and Application of Reinforced Grass for llydrotechnical Structures" and has been supported by CTU grant No.2062.

822

Section 17

PRODUCTION SYSTEMS

&

TECHNOLOGY

WORKSHOP 95 PRODUCTION SYSTEMS & TECHNOLOGY

MATHEMATICAL MODELLING OF THE INJECTION MECHANISMS OF THE DIE CASTING MACHINES

P. Vávra, P. Sýkora

CTU, Fac. of Mech. Eng., Dcpt. of Machines & Equipment for Eng. Prod. Horská 3, 12800 Praha 2

Key words: die casting machine, injection mechanism, method of characterisitics

During the development of the injection mechanism without multiplying gear in the company of "TOS Rakovnik" there was an idea to verify the properties of the original injection mechanisms of the old machines produced by "Original Polak" in the years 1930-1940. Because the main function of the injection mechanism is to transport molten metal quickly from the filling chamber to the die and to act by the high pressure during the solidifying, we studied how the pressure in the injection cylinder depends on various parameters.

Hydraulic circuit was solved by the method of characteristics with respect to the pipe length between the accumulator and the hydraulic motor. The simplified computing scheme you can see in the Fig. 1. It contains four types of nodes: accumulator, hydraulic motor, resistance and pipe.

r~\

L

Trhlib-L

+« * i

Trh2*h-1Q0D

L=»*át J , *

Fig. 1

The pressure pattern was observed in the injection cylinder from the time, when molten metal filled the die cavity and so the piston stopped. For example the pressures in the cylinder after the stopping of the piston are shown in the Fig. 2. We can see that there is a velocity limit, when the undesirable cavitation begins.

825

WORKSHOP 95 PRODUCTION SYSTEMS к TECHNOLOGY

Q.

a

0,3 m/s 0.6 m/s 0.9 m/s

.1.2 m/s

Fig. 2

In the Fig. 3 is shown the influence of the time, when the piston decelerates from the velocity v = 0.6 m/s to v = 0 m/s. You can well see that the pressure in the injection cylinder decreases very much in cca 50 ms. It is the time, when the molten metal solidifies.

s. a

40

35

30

25

20

15

10

5

0

• • •

s<^ r> ; • i t * ,

/ /

w ' /

и-

""^A-..

' Vs

\VM Л \ I*.

r ч^л

. . .

....

« / - ^ / / . -

. . / / . / . , • / • / •

/ / /

/ / / .'

/ • / • • •

1 I 0 ms — 17.5 mš"---

. . 15.0 ms 22.5 ms - -i |

"^V, I A\-i

\ \ \ \ •V • ч \ ч

4. ' . .„.

0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 t[s]

Fig. 3

The graphs show, why the quality of the castings made on the original Polak's die casting machines with the cold chamber (he patented them in 1927) varied. The graphs and the others results also evoke, how to design the hydraulic circuit of the injection mechanisms and give reasons for evolution of the injections mechan^ms in the last 50 years.

826


THE COMPUTER UTILIZATION IN DESIGN OF THE DIE CLOSING UNIT OF DIECASTING MACHINES

S. Maňas, M. Hladík, Т. Vampola*

CTU, Fac. of Mechanical Eng., Dept. of Machines & Equipment for Eng. Pr Horská 4, 128 00 Praha 2

*CTU, Fac. of Mechanical Eng., Dept. of Mechanics Karlovo nám. 13, 121 35 Praha 2

Key words: toggle locking die close mechanism, lie bar, tie bar nuts, machine closing cylinder, ejection cylinder, prototype drawings

The computers encroach on all fields of industry and by their increasing power and utility quality directly influence all branches of mechanical engineering. Computers utilization today is becoming an inevitable condition of further faster and more intensive development of a great number of professions. It is obvious that computers gradually come into one's own in diccasting as well.

The utilization of the computers in a design of diecasting machines (DM) and peripheries is only at the beginning, but it will find considerable expansion, because the shortening of preproduction phases is necessary in this field too. After the analysis of necessity of the users program for DM design the die closing unit and the calculations and design of the toggle locking die close mechanism in concrete were prioritized.

The optimizing program OPTIM was used for the design of the toggle locking mechanism. It allows to find mechanism components proportions in appropriate relations of the considered series of the DM (for the present for DM with locking force of 2500, 4000 and 6300 kN), Proportions gained in this manner were processed by the program MCADA, which allows to effect kinematic analysis of the whole mechanism including the ratio calculations. The ratio was for the concrete mechanism positions checked by graphic method based on principle of virtual output and compared with analytically deduced relations for the ratio. The analytical relations were gained by the method of virtual work. The deduced relations were processed by the program MATLAB and they served for the checking of the ratio and consequently to the retrieval of the toggle locking die close mechanism dimensions by program OPTIM.

The second direction, which was followed, was to maximally facilitate designer's work designing in the AutoCAD system and from this system to call the necessary computational routines. Furthermore it was necessary to ensure the cooperation with database, because the computational mode should allow not only to enter the new data in a process of the new DM size design, but to enter the parameters of the already existing mechanism (from the appropriate database) for possible further modification or computer checking as well.

The conception of the integrated environment for the design of closing unit considers four compute modules :

- program for calculation and design of the toggle locking die close mechanism - components of toggle locking mechanism (it is usčd for solving and consecutive drawing, all

827


parametrised values arc calculated and it is possible to calculate and draw the ratio characteristics)

- program for calculation and drawing of the tic bars and tic bar nuts of the DM (it is used for static calculation of a tensile stress, deformations and stiffness, for checking the dynamic load namely in the case of a tensile stress and in the case of a compound tensile stress with additional bend as well, and for consecutive drawing)

- program for calculation and design of the machine closing cylinder (it is used for the design °f the basic dimensions and for all necessary strength checks)

- program for calculation and design of the ejection cylinder (it is used for the design of the basic dimensions, for necessary checks and consecutive drawing of the prototype drawings).

The basic I/O data file, that is processed in a first module, is a file *.KLM . In the case this file does not exist, it is created at the first pass. The second program module furthermore uses a file *.MAP for drawing of the front nut, a file *.MAZ for drawing of the back nut and a file *.SLO for drawing of the tie bar. The third and fourth module use the files *.HXU and *.HXV. After the finishing the calculations it is allowed to print the protocols. '

The work with the first program module was divided into four phases: In the first phase there are performed needed calculations and it is possible to draw the

toggle locking mechanism (its important parts), that means the join link, short link and the long l'nk in the important mutual positions.

In the second phase there is allowed to add and draw further important link of the mechanism - crosshead. There are also drawn three important positions and it is proceeded to the examination of mutual positions of links, which is used for the creation of the working drawings.

In the third phase it is possible to draw a view of the closing unit from both sides of the unit including the stationary platen, moving platen, base, tie bars, tic bar nuts and the important cross-section.

In the fourth phase the already mentioned prototype drawings become the basis of working drawings of the following parts: short link, long link, join link, crosshead, big pin, small pin, small and long pin bush, tie bar and tie bar nuts. All these working drawings are made according to valid standards.

The calculating programs are processed in virtue of analysis of the experienced designers in the programming environment С using the shell Vitamin C. This shell allows easy creation and manipulation with the windows for enter data, text dumps, etc. The internal programming language of the AutoCAD the AutoLISP was used for the creation of the drawing documentation. The prototype drawings are drawn parametricaly using data gained from the calculations. The shell of the AutoCAD the Profi was used to the finishing of the working drawings.

Users' skills both of the basic method and principles of the toggle locking mechanism calculating and design and of using the AutoCAD system are supposed for the work and for using the mentioned program system.

This research has been conducted at the Department of Machines & Equipment for Engineering Production as part of the research project "Mechanisms of machines and attachments for automated diecasting centers" and has been supported by CTU grant No. 08 28175.

828


INCREASING OF FORMING MACHINE PRODUCTIVITY

B. Rudolf, V. Sefrna

CTU, Fac. of Mechanical Eng., Dept. of Machines & Equipment for Eng. Pr Horská 3, 12S 00 Praha2

Key words: productivity, forming machine, mechanization and automation

The share of forming machines in mechanical engineering is very significant. According to statistical data, approximately 35% of all parts used in mechanical engineering are produced by forming. It is the reason why increasing of forming machine productivity is so important.

If we are speaking about increasing of forming machine productivity it is necessary to mention what sort of forming we have in mind: technologies of cold forming and that of hot forming are two very different technologies with very different conditions.

Increasing of forming machine productivity thus depends on

- technology used at a forming machine, - type of forming machine, and - degree of mechanization and automation of a forming process.

If we think over a productivity in dependence on technology used in forming, we consider one working cycle and speak about a productivity withing this cycle. Such productivity depends

- in cold forming on working time and the area of a formed part, - in hot forming on working time and the volume of a formed part, - in shearing on working time and the circumference of a cut part.

For calculation of productivity during a long-term operation, the value of the productivity is given by a productivity within one working cycle, a time constant and a reliability factor.

Speaking about a productivity in dependence on the type of a forming machine, it is necessary first of all to divide forming machines into three basic types:

- forming machines controlled by stroke, - forming machines controlled by force, and - forming machines controlled by energy.

In forming machines controlled by stroke, a ram of the machine makes — through kinematics of the drive of a machine — a given stroke. The amount of force acting on the ram depends on the speed of a crankshaft. The value of the productivity will be different for a continuous operation and for an intermittent operation.

In forming machines controlled by force, the intensity of force acting on a ram does not depend on the position of a ram. Productivity is dependent on the time of subsequent strokes that can be utilized (in accordance with an odjustment of the total stroke, that consists of working stroke and a dead stroke) and on the speed of ram in the range of total stroke.

829


In forming machines controlled by energy, the productivity is dependent on the speed of subsequent strokes. We can divide these machines into two types: single acting machines and double acting machines. The speed of subsequent strokes of single acting machines depends on the height of a ram fall. The speed of subsequent strokes of double acting machines is possible to increase significantly using higher accelerating forces in reduced strokes.

Incroassing of a productivity with respect to the degree of mechanization and automation of a machine varies according to the type of a machine and is totally different using standard machines, single purpose machines, semi-automatic forming machines, automatic forming machines, or NC forming machines. The same difference is when means of mechanization and automation used in forming process are standard ones or dedicated ones. The measure of the degree of mechanization and automation is the proportion of the total working time without using such means to the total working time with these means.

Another important factor connected with mechanization and automation of machines is so called mobility of a workplace. It is given by the proportion of the batch volume to the sum of the batch volume and the total time for forming tool exchange, multiplied by the productivity. And the productivity is given, in general, by the proportion of the batch volume to the batch working time.

Finally, it is possible to state that increassing of forming machine productivity is dependent — like in all manufacturing machines — on shortening of waiting time. Such shortening is a goal for increassing of the degree of mechanization and automation of non-technological operations.

References: [1] RUDOLF, В.: Increasing of forming equipment productivity [2] SEFRNA, V.: Characteristic of rcability in proces of modeling alternative prod.syslems

This research has been conducted al the Department of Machines & Equipment for Eng. Prod, as part of the research project "increasing of forming equipment productivity" and has been supported by Czech Grant Agency.

830

WORKSHOP 95 PRODUCTION SYSTEMS fc TECHNOLOGY

OPTIMIZATION OF A CUTTING PATH

G. Dohnal

CTU, Fac. of Mechanical Eng., DcpL of Technical Mathematics Karlovo náin. 13, 121 35 Praha 2

Key words: optimization, cutting path, oriented graph

Introduction. Let us consider the following problem of optimalizalion of the path of cutting tool: The drawing is given in the form of plane (2D) graph, i.e. as the set of points (vertices) which are connected by strokes (lines, arcs or any other single smooth curves, which form a set of graph edges). Any edge of the graph corresponds to one cutting line in plane desk. We wish to minimize loss which follows from movings of cutting tool (without cutting). The cutting tool has to pass through every graph edge just once and the number and total length of movings have to be minimal. In the ideal case the cutting tool will pass through graph by one continuous stroke.

Formulation of the problem. Let, G be continuous and finite 2D graph without orientation

G = {XI,...,XN,SI,.--,SM},

with nodes A'i , . . . , А'дг and edges s t , • • •, «л/-The oriented graph G is called the orientation of graph G, if its nodes arc the same as

of G and its edges s i , . . . ,зд/ are oriented. The graph G is domain of the orientation G. Evidently, there exist 2Л/ different orientations of the graph G.

A subgraph К of graph G is called continuous (continuously oriental), if there exist two nodes Ks and Kg in К and at most one oriented path1, which starts in A's, connects all nodes of К and finishs in A'g.

We can show thai any orientation G can be decomposed into continuous subgraphs {/\'i,..., A'n}, such that (J"_, A',- = К and Л',- П Kj does not include any edge of G for all i J € { 1 , . . . , n], i ф j . The discontinuity of graph G is defined by the following formula

v{G) = mini<fc,(<j d(h'k, Ki)

where d(K,L) = m'm{d{I<s,Ls),d(Ks, LE),d(I<E, l->s),d(h'E, LE)} and d(l<s, Ls) denotes the Eukleidian distance of two nodes A's and Ls of graph G.

Hence, the optimalization problem can be formulated as follows: We have to find the orientation of G which has minimal discontinuity between all pos

sible orientations of G.

The solution of problem. The above problem can be solved by successive reductions of graph G. At first, we shall introduce the following operation: merging and contraction of graph nodes.

a) Merging. If there exists a node у of order 2, in graph G, with "neighbours" x and 2 (Fig. la), then we shall reduce G into G', in which the path x —> у ~> z will be replaced

'The patli is the connection in which every edge is included only once.

831


by path {.ту/} —• г and other nodes and edges will stay without changes (the node у is "merged" with node a: into new node ,TJ/, see Pig. lb).

i у г^». ^^{xy} г^~»

Fig. la Fig. 11,

b) Contraction. If there exists a cycle Xj —» . . . —• .r, of length j in G (Fig. 2a for j = 3), then we shall reduce G into G' so that the cycle x\ —» . . . —> Xj will be replaced by single node {,n . . . ,т,} (the cycle will be "contracted" into single node, sec Fig. 2b).

I | XI

Fig. 2a

Above mentioned reductions will perform in the following conditioned loop:

IF there ex i s t s a node of order 2 in graph G THEN do merging; REPEAT in reduced graph

IF a cycle of length i = 3 , 4 , . . . ex is t s THEN do contraction; IF a node of order 2 exis ts THEN do merging;

UNTIL the re ex is t s some cycle.

This algorithm stops when no cycle is in the resulting graph G'. If G is Eulerian, then G" will be reduced into only one node. In other cases, G' will contain the same number of two-node components as the number of members contained in the minimal decomposition ofG.

References: [1] SEDLÁČEK, J.: Kombinalo rics in theory and in practice (The intioduction in theory

of graphs) Nakladatelství ČSAV, Prahn 1964. [2] ORE, 0.: Graphs and their uses. Mir, Moskva 1965

832


SYSTEM FOR PRODUCTION OF GEOMETRICALLY COMPLICATED

SURFACES IN FLOW MACHINES

J. Rybin, J. Neústupa*, T. Curda

CTU, Рас. of Mechanical Eng., Dept. of Machines & Equipment for Eng. Pr Trojanova 13, 120 00 Praha 2

*CTU, Fac. of Mechanical Eng., Dept. of Technical Mathematics Karlovo nám.13, 128 00 Praha 2

Key words: CAD-СЛМ, production of radial turbocompressors, interpolation methods, post-processors

The problem was solved on several levels which arc connected one with another: - The continuation of the development of the system of programs which enables an

automatic production of an input compressor of an airplane engine on a milling cutter. We have created the mathematical model which describes the motion of the tool of the milling cutter around the profiles in the neighbourhood of a frontal edge in accordance with the requirements concerning a special geometrical form of the profile in this part. The model respects especially the radius of the frontal edge in its lower and upper part and it enables as smooth connection with the following part of the profile as it is needed. The mathematical model was projected into the program which was tested on particular examples. Designers of airplane engines define the form of compressor blades in such a way that their exact production would be theoretically possible by a tool of the zero thickness. This cannot be realized. This is why the production is never absolutely correct. Of course, there are also other reasons which have a technological background - for example, it is not possible to work up by the tool in a position where its velocity is equal to zero in the domain where it actively takes away a material. We have changed some parts of the mathematical model so that the in correctness of the production was minimized. The changes were al so involved to the system of programs.

- The programming of the CAM system for the working up of the compressor blades is realized on the computed in the environment of MS FORTRAN 5.1. This environment is optimal from the point of view of usage of algorithms and programs which were already finished, plenty of libraries and subprograms and good properties of the compiler in the field of scientific and technical computations. We have used some subroutines which we developed to similar purposes and which worked on other computers in the past. These subroutines were once more tested and we have involved them into quite a new architecture of the system which is much more flexible and satisfies new and extended requirements. Its idea is shown on the following scheme.

The complete system of programs is again tested at this time. We have created several programs with a graphiccal output which serve for the first control of correctness of the used mathematical model. Its algorithms arc controlled by means of the CAD system Personal Designer and the correct function of the post-processor part was tested by a direct syntax control on the milling cutter. One of the last steps which must be done before final tests simu laling conditions of a real manufacturing is the choice and verification of an appropriate

833


interpolation method which would be applicable in as wide class of alternative surfaces of blade pro files as possible.

CAM system ROTOR

Input files:

* .da l

*.tlb

' . rnch

User interface

Modul tor creating and editing input files

Geomelry of the part

Tools library

Machine definition

Modul of primary Interpol*', en

1,'Ш lit main n-ečíi

S«ccrsar/ rtirpc'avci

Modul of technol processor and postprocessor

Utilities and tools

NC program Check outputs

*.nc Output files . DNC

NC milling machine

- Due to the up to date developement in the field of CAD-CAM and actual possibilities of our department, we have started the cooperation which should lead to the implementation of the program ming system CIMATRON 90. We have created and verified in practice the postprocessor СШ720, version 1, for the continuous control in three axes in a cooperation with the firm GRALL. The post-processor satisfies the requirements of the system CNC836. The whole capability of the solution was verified and demonstiated in practice by the production of a part of a compressor blade with a complicated form - all by means the DNC-CNC communication on the working up center MCFH 40 from the production of ZPS. Para lelly we are continuing the developement of a full 5-axes version of the postprocessor so that it should be a sufficient tool for the describtion and practical realization of compressor surfaces which would be complementary to the surfaces of rotors.

- The inovation of CNC interpret aswell as DNC-CNC communication is done in accordance with the developement of realized program and technological solutions.

This research lias been conducted at the Department of Machines & Equipment for Eng. Production as pari of the research project "CAD-СЛМ system for production of geometric complicated surfaces of jet engines and turbines" and has been supported by CTU grant No. 8120.

834


RESEARCH ON NEW CUTTING FLUIDS

J . Mádl

CTU, Fac. of Mechanical Eng., Dcpt. of Machining & Process Planning Technická 4, 166 07 Praha 6

Key words: cutting fluid, machining, research, environment

World environmental aim is the replacement of traditional oil cutting fluids by new environmentally suitable ones.

The main task of the research is the project of new progressive experimental methods for higher quality of the cutting fluid research. The project is aimed at research of the new group of newly developed cutting fluids produced by TRIG A. This producer cooperates with CTU Prague on this project supported by Czech Republic Grant Agency.

In the past, the cooperation with the TRIG A producer led to the development of new environmentally harmless cutting fluids.

The research of the cutting fluid properties is rather complicated from the point of view of cutting process. A lot of various characteristics have to be followed. The focus of research arc cutting forces, cutting power, tool wear, built-up edge formation, characteristics of workpiecc surface (e.i. roughness, accuracy), material deformation during chip formation etc.

R > , •» (

T. «150 ,_

170

CM 00

Fig. 1: Tool (1-body, 2-clamp, 3-screw, 4-cutting tool)

Fig. 2: Cutting tool

835


One of the important characteristics of cutting fluids is the cutting time (or the mean value of feed) for the constant length of machining with constant feed force cutting. These characteristics are dependent on chip formation, friction between the cutting tool and work-piece, specific cutting force, built-up edge formation etc.

Practical application of machining with constant feed force in various technologies is not simple. Difficulties with this application in drilling are relatively easy to solve in comparsion with other technologies. But, to use the same twist drill geometry is difficult. Except for this fact, cutting speed, clearance and face angles change along the edge.

A new type of tool for drilling with constant feed force was therefore designed (Fig. 1 and Fig. 2). This type of cutting tool represents orthogonal cutting. Repeatability of the tool geometry is of high degree.

Cutting tests with this new tool and twist drill have made comparability of the results possible, when machining with various cutting fluids. However, the results for the new cutting tool are of higher quality. As an example, Fig. 3 gives the results of the experiment with new tool machining. Each measuring was repeated four times. Number of revolutions - 85 per minute.

This method of finding one of the characteristics of machining process when testing cutting fluid, represents one of the steps of the project.

cutting f luid

Fig. 3: Constant feed force test

References:

[1] MÁDL, J. - BLÁHA, K.: Research of New Progressive Experimental Methods for Newly Developed Environmental Cutting Fluids. Grant No. 101/94/1556 of Grant Agency of the Czech Republic. Praha 1994.

836

WORKSHOP 95 PRODUCTION SYSTEMS it TECHNOLOGY

APPLICATION OF PSD IN ROBOTICS

R. Malik, P . Gonda

TU, Fac. of Mechanical Eng., Dcpt. of Production Machines and Systems Technická 2, 616 69 Brno

Key words: PSD sensors, robot's assembling, distance measurement

PSD (Position Sensitive Detectors) are optoelectronic sensors that provide continuous position data of light spots travelling over their photosensitive surfaces. PSD is based on a semiconductor and its structure is similar to PIN photodiodes. PSD have many advantages such as the high position resolution, fast response speed and simple operating circuits. The big feature is that the position data are independent of the focus of the light spot on the detector. PSD are produced in various configurations as one-dimensional and two-dimensional detection types.

Principle: When a light spot falls on the PSD, an electric charge proportional to the light energy is generated at the incident position. This electric charge is driven through the resistive P- layer and collected by the electrodes. Since the resistivity of the P-layer is uniform, the photocurrent collected by an electrode is inversely proportional to the distance between the incident position and the electrode. It is possible to obtain the following formula for the photocurrents I\ and /2 collected by the electrodes: (/2 - Л)/(Л + /2) = x/L. See Fig. 1.

OUTPUT I I

1 incident OUTPUT 12

s • l ight *

rjb 1 Ушжштттмт/Шжжшж.

Ш?//////////////////^^^^^^

P-layer

I-layer

N-layer

Fig. 1: Principle of the PSD

Applications of the PSD: distance measurement; displacement and vibrations monitoring; optical position and angle sensing.

We would like to present our experiences in monitoring a distance deviation of the end effector of robot in robot assembling application. We have used both kinds of the PSD (ID and 2D). We have tested such parameters as the dependence between output voltage from the ID PSD and position of the spot, where the light falls on the surface of the ID PSD, see in Fig. 2. In accordance with measurement we tested a linear dependence of the output signal. We reached resolution 0.005 mm for distance measurement 12 mm (S 3932), with max. position detection error 0.05 mm and for S 3270 was resolution 0.015 mm for distance measurement 37 mm, with max. position error 0.15 mm.

837

WORKSHOP 95 PRODUCTION SYSTEMS Ss TECHNOLOGY

500

Fig. 2: The dependence output voltage/position of the ID PSD

2D PSD (S2044) was installed in robot's grippcr see Fig. 3. It was tested whether it is possible to use its output voltage (from two directions) to drive assembling task on robot APR 20. Robot's grippcr consists of two main parts, which are connected together by flexible membrane. PSD is placed in the first part of the grippcr, emitting diode (Ilamamatsu L1915) is located in the second one. The place, where the light falls on the PSD, depends on the degree of the membrane deformation. The deformation can be caused by interaction between a peg and a hole.

Fig. 3: APR 20's gripper

References:

[1] HAMAMATSU: One-Dimensional PSD S3979, S3931, S3932. Hamamatsu Photonics K.K., Solid State Division.

[2] HAMAMATSU: Urge-Ana PSD Series (long-Area ID PSD and 2D PSD). Hamamatsu Photonics K.K., Solid State Division.

The work described in litis paper lias been partially granted by the Technical University of Brno as a research project No.: D19/93-94 "Applied Sensors and Al Implementation".

838


ULTRASONIC SCANNING SYSTEM FOR MOBILE ROBOTS

V. Opluštil, D. Svačina

TU, Рас. of Mechanical Eng., Dept. of Production Machines and Systems Technická 2, 616 69 Brno

Key words: ultrasonic sensor, mobile robot, absolute localisation, object recognition

Sensory systems using ultrasonic wave propagation in the air have been used with variable success in robotics. Many of them have been applied as standard sensors for industrial automation and the other ones has been used for distance measurements using a timc-of-flight (TOP) method [1], [2]. Some hcivc reported considerable success when using these systems for localisation, mapping and navigation in autonomous locomotion robots and vehicles (ALR, ALV), while others have reported problems great enough to make them unusable [3]. Many such problems as a specular reflection, a multiple reflection and a poor lateral resolution have been known and they arc very widely reported in many publications. Some references arc oriented to constructing a local environmental map using of the fundamental observation made by Kite and Sicgcl in [4]. Some references are based on a multi-sensory system interpretation and for a known but changeable environment in order to navigate ALR and to detect and avoid unexpected objects. Some solutions are orientated to lacalisation of objects and recognition of its orientation in the environment [5]. We have practiced our ultrasonic scanning sensory system (USS) in a known real environment with defined orthogonal coordinates x,y (for range from 0.0 m to 5.0 m) with practical resolution of 1.0 cm, i.e. axis distance step. Our experimental equipment is described in Fig. 1. For scanning process and data acquisition we have used the angle resolution of 12 cleg. ,it is appropriate to use this method in real time for ALR application. For a maximum distance of measurement, approximately 500 cm (30 ms). and scanning rate of 360 deg. / 1 s, i.e. 30 samples per 360 deg. We have used a data acquisition board CC-ADC 2 of Czech production for IBM PC 3S6/40. A software tool is made in Turbo Pascal 7.0 language. We have controlled a motor of the USS by means of the D/A converter of CC-ADC 2 board. The detection of scanning angle is realized by an optoelectronic sensor.

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One of the important tasks is concerned with ALR navigation in a known environment including unknown and changeable objects. The solution is to equip ALR by the ability

839

WORKSHOP 96 PRODUCTION SYSTEMS fe TECHNOLOGY

to navigate around unexpected obstacles. Wc managed to develop the Mixed model which is based on knowledge of a geometrical map of known environment and stationary objects and some failures derived from the real characteristic of analyzed ultrasonic pulses (echoes) reflected from representative objects belonging to the known environment, i.c, the objects as walls, edges, corners and openings. We triod to associate these features and features coming from the simulation model which include parameters derived from the real characteristic of the ultrasonic transducer and the number of reflected pulses related to the reference points of the known environment. The sequence of these features is stored in t he computer memory as a geometrical model. The recognition of the reference point and paitial recognition of unknown objects and ЛЫ1 localisation are processed by software algorithm,

Wc performed analysis of known objects (corners, edges and walls) with lespect to the geometrical map of the known environment. We tried to determine the basic features of reflected ultrasonic pulses and their numbers for the defined position of the USS and the scanning angle. The analysis have been showed some results. The distances relating to the reflected pulses from the object arc invariant to the scanning angle of the USS in the range of angle of the ultrasonic emitting beam. Satisfactory results were obtained from walls, and comers but were not suitable, it seems, to solve analysis of openings and edges (convex corners) using our USS with the wide ultrasonic beam. The experimental results in the first step helped us to develop a simulation model. This model in the main assumes that the known environment consists of objects with specular reflected planes normal to the plane of ALR movement basis. Wc also assume a point approximation of emitting plane of ultrasonic transducer. This simulation model makes possible a prediction of reflected pulses and related distance measurement of object, This model covers multiple reflections and some features from the known real environment (reference points), The Mixed model enables absolute localization of ALR in the partially known environment and simultaneously localisation and determination of orientation of unknown objects.

References: [1] LINDSTEDT, G. - OLSSON, G.: Using Ultrasonics for Sensing in a Robotics Environ

ment. IEEE Proc, of the Int. Conference on Robotics and Automation, pp. 671-676, Atlanta, Georgia, US, 1993

[2] HANUS, J. - OPLUSTIL, V.: Multi-Sensor System of Intelligent Control for Flexible Industrial Robots. Proc. of the 2nd Int. Conference on Automation, Robotics and Computer Vision, Vol. 2, pp. IA-4.6.1 - 1A-4.G.5, Singapore, 1992

[3] JARVIS, R, A.: Sensors, Distance Measurement. Dorf, R.C. and Nof, S.Y,lnt. Encyk-lopedia of Rotics, John Wiley and Sons, pp. 1493 - 1505, 1988

[4] KUC, R. - SIEGEL, M. W.: Physicallg Based Simulation Model for Acoustic Sensor Robot Navigation. IEEE Trans. Pattern Analysis and Machine Intelligence, Vol. 9, No. 6, pp. 766 - 778, 19S7

[5] OPLUSTIL, V. - SVAČINA, I).: Ultrasonic Scanning Sensory System and Its Application in a Partially Known Environment. Proc. of the Int. Conference on European Robotics and Intelligent Systems, Vol. 3, pp. 1761 - 1770, Malaga, Spain, 1994

77n« research has been conducted at the Department of Production Machines and Systems, as part of the research project "Applied Sensorics and AI Implementation" and has been supported by TU grant No. D19/93-9/,.

840


TESTING THE QUALITY A. Fiala, L. Hobst, etc.

HTU, Brno Technical University, Institute of Quality Kounicova 67a, 602 00 Brno

Key words: quality, certification, accreditation

International norm ISO 8402 defines quality as a total complex of properties and characters of a product or service which gives it ability to satisfy prescribed or expected needs. Today's customer has various demands but he always requires the purchased product to be demonstrably first-class. The evidence of the quality of the particular product can be presented in the form of the reports on the results or the evidence is obtained from the customer who used the product. However, the evidence refers to the past event — a considerable disadvantage — if the customer finds that he lias bought a faulty pro duct. Therefore, lately the attention is transferred to the warranties of the quality — the customer is interested in the certificate which evokes the confidence that the product will not be faulty in the long-lasting future. Such warranties for "the future quality" can be based not on the results of the control but only on the working system of quality on a supplier's part.

The system of quality which is supposed to be the source of the warranties must be credible. The credibility of the quality system consists in the fact that it is formed according to the generally adopted principles and presented and sufficiently clearly. The contemporary standard for quality systems are international norms ISO 9000. To strengthen the effect of the clear pre sentation, the system of certifications which supposes the involvement of the third independent and impartial side that checks and verifies the fulfilment of criteria valid for quality systems was created. The certification bodies similarly as the testing laboratories which arc to supply the credible reports on the parametres of the chosen product samples must be accredited with their activity. The trend of increasing demandsfor quality warranties causes the rise of accreditation and certification systems which use harmonized norms and which arc connected with equally recognized criteria.

It is the existence of independent organizations and the sufficient number of appropriately qualified and morally-freely disposed engineers which is necessary for succesfull working of accreditation and certification systems. This fact opens a large field of activities for universities. Universities are from the view-point of accreditation criteria independent institutions and they manage experts of various professions. University laboratories can work as testing or calibration laboratories. Universities can educate graduates for the application in the quality system — as managers, auditors and testing technicians. The project of Brno Technical University "Testing the Quality of Materials and Designs in Target Entering into the National System of Quality Proving in All Forms of the Participation" was based on this idea. For this solution, workplaces of three faculties — Civil, Electrical and Mechanical Engineering — associated. The results of the project solution can be divided into three groups according to their application possibilities:

• to achieve the state of competence for the accreditation in chosen laboratories;

• to create and verify the programme of graduate education for positions in quality systems of firms and also in the authorities of the accreditation system;

841

WORKSHOP 95 PRODUCTION SYSTEMS it TECHNOLOGY

• to harmonize activities of individual faculties so that all elements (people, workplaces) could present themselvesas the subjects of Brno Technical University.

In the period of the project solution the conditions for the accreditation of testing or calibration laboratories according to EN 45001 were gradually created in three workplaces at the Faculty of Civil Engineering and in two workplaces at the Faculty of Mechanical Engineering. They are the testing room at the Faculty of Civil Engineering, the Institut of Building Materials and Testing Methods and the Radiation Dcfectoscopy Centre at the Faculty of Civil Engineering, the laboratory of defectoscopy in the Institut of Material Engineering and the Centre of Calibration Service at the Department of Quality Management at the Faculty of Mechanical Engineering. The accreditation by the Czech Institute for Accreditation has not been clone yet because contemporary accreditation charges highly exceed the possibilities of university workplaces. The importance of the task to educate the whole population to the quality in our country has not been appreciated yet, which reflected among others in the fact that Grant Agency of the Czech Republic nor the Progress Fund of the Universities did not show more interest in proposals which were presented by the members of research team either individually or collectively. The grant from these funds could provide some means for finishing the accreditation, another activity could derive from the profits of provided services. All the laboratories mentioned above have a good reputation in professional public, which is from the viewpoint of application a sufficient condition for complying with the necessary condition of the accreditation according to EN 45001.

In the field of graduate education valuable experience was obtained, which enabled to lay out the study programme for specialization "Quality control" in the fourth and fifth years of engineer studies. The basis of the study programme are system engineering, applied statistics, economic disciplines, management, law, psychology, sociology and ecology. The response from the workplaces where the graduates are employed is positive. The qualification of the graduates is with the demands for quality managers which were formulated by the European Organization for Quality. The good orientation in "non-technical" disciplines guarantees the graduates the rapid adaptation in privatized firms. Unfortunately, here the contempt of the environs is also negatively shown, which is caused by insufficient knowledge of importance of quality in the world where the strong function is presented by the market mechanism.

To strengthen the effect of the achieved results, the members of the research teams established the association called: "The Institute of Quality, Brno Technical University". The aim of the association is to establish the common base for external and internal activities supporting quality systems under the name of Brno Technical University. This step was also positive because a distinct signal was send to the public that the university is able to help the firms in introducing quality systems effectively and competently and also that the university is involved in the problems of quality worthy of establishing "The Institute of Quality".

This research has been conducted at "Institute of Quality of Brno Technical University" as part of the research project "Testing the Quality of Materials and Designs in Target Entering into the National Systejn of Quality Proving in All Forms of the Participation" and has been supported by BTU grant No.D/2.

842


ELABORATION OF METHOD FOR EVALUATION

OF SHEET-METAL FORMABILITY R. Cada, S. Rusz

VSB - TU Ostrava, Fac. of Mechanical Engineering, Department of Mechanical Technology třída 17. listopadu, 708 33 Ostrava- Porubá

Key words: formability, sheet-metal, anisotropy, deep drawing, stamping, limit deformation, steel strip, mechanical properties, exponent of deformation hardening

The paper concerns evaluation of formability of steel strips, which are used in Autopal Nový Jičín, Ltd. for production of oval paraboloid headlamp reflectors.

In this enterprise the practice has shown, that the quality of intricate deep stampings considerably depends on the properties of steel strips, which they are produced from. In Autopal Nový .Jičín, Ltd. the strips of steel 11 305.21, which are produced in joint-stock company VSŽ Košice, arc currently used for deep drawing of intricate stampings. With respect to changeable properties of separate deliveries of this steel strips, which disgracely influence on the production of stampings, in the enterprise has been decided to test the suitability of foreign steel strip St 4 (especially deep-drawing grade by DIN 1G24) for deep drawing of intricate stampings.

The steel strip St 4 with dimensions 0,80 x 250 mm in common with the certificate about accomplished tests by DIN 50 049 has been dclivericd to Autopal Nový Jičín, Ltd. by the firm С D. Walzholz (Germany).

With respect to the fact, that the deliveried certificate has not contained the directional and medium values of mechanical properties, coefficients of area and normal anisotropy of mechanical properties of sheet metal, the directional and medium values of exponent of deformation hardening of sheet metal not even deepening by Erichscn, it has not been possible to classify more exactly the deliveried steel strip St 4 according to formability not even to compare it with the currently used steel strip 11 305.21.

Since the price of the steel strip St 4 from the firm C. D. Walzholz more than twice exceeds the price of the steel strip 11 305.21 from the joint-stock company VSŽ Košice, the detailed evaluation of their properties and reciprocal comparison of formability of the steel strips mentioned above has been accomplished by the author on Department of Mechanical Technology, Faculty of Mechanical Engineering, University of Mining and Metallurgy in Ostrava on application of Autopal Nový Jičín, Ltd. The aim of this evaluation has been in getting of foundations for decision, which properties of sheet metal have the principal influence upon the success of deep drawing and from which steel strip it will be better to produce the oval paraboloid headlamp reflectors in Autopal Nový Jičín, Ltd. in the next period.

DIN and CSN suppose, that the worst mechanical properties from standpoint of formability exist at sheet-metal in direction of 90° compared with the direction of rolling. However this supposition does not consent to verified directional course of mechanical properties in plane of sheet-metal as at steel strip St 4, as at steel 11 305.21. According to the demands of appertaining standards on mechanical properties it is not possible to judge the sheet-metal

843


formability right, which can make problems at deep drawing of stampings in practice. From the facts mentioned above follows, that at high-class sorts of deep-drawing sheet-metal it is necessary to evaluate also the directional values of mechanical properties.

It is not possible to judge right the suitability of sheet-metal for deep drawing only according to mechanical properties, determined by tensile tests, but first of all according to medium value of exponent of deformation hardening and medium value of coefficient of normal anisotropy of sheet-metal mechanical properties. Decisive values of these coefficients for sorting of sheets according to their formabilily has not been determined in standards yet.

At tested steel strip St 4 the lower value of medium exponent of deformation hardening has been found out (nm = 0,158) than it is current at steel strip 11 305.21 (n„, = 0,185). This reality is caused by great content of impurity elements at steel strip St 4 and fineness of ferrite grain (G = 10,5). According to lower nm value at steel strip St 4 the speed of deformation hardening at drawing is lower, the transposition of plastic deformations from places with great initial stress (biaxial tension zone) to places with lower initial stress is slow and that is why less uniform situation of deformations on stamping arises. So at drawing from steel strip St 4 there is greater danger of arising of secondary waviness or integrity failure than at drawing from steel 11 305.21.

References: [1] DAVIES, G. J. - BURKE, M. A. - OZTURK, Т.: The Processing of Sheet for Optimal

Formability. Sheet Metal Industries, GO, 1983, č. 6. [2] POLLÁK, L.: Anizotropi a a hlbokoťažnosť ocefových plechov. Bratislava, Alfa 1978. [3] AVERKIJEV, A. J.: Metody ocenki štampujemosti listovogo metalla. Moskva, Maši-

nostrojenije 1985. [4] CADA, R.: Příspěvek k řešeni lisovatelnosli výtažků nepravidelných tvarů z tenkých

plechů. (Kandidátská disertace). Ostrava, VSB 19S9. [5] CADA, R.: Rozbor napjatosti a deformací při postupovém tažení oválných paraboloid-

nich zrcadel 5620.74 P™ světlomety automobilů VAZ 2105. (Technická zpráva). Ostrava, VSB 1990.

This research has been conducted at the Department of Mechanical Technology, Faculty of Mechanical Engineering, VŠB - TU Ostrava as a part of the research project "Elaboration of method for evaluation of sheet-metal formability and its experimental verification on deep stampings with the use of method of deformation networks", which has been applied for a grant at Grant Agency of the Czech Republic (registration number 101/95/1174)-

844


EXAMINATION OF DIFFERENT MATERIALS PROPERTIES

IN METAL FORMING L. Janíček, L. Kolařík, R. Hudec*, J. Petruška**

TU, Fac. of Mechanical Eng,, 1MT, Dept. of Metal Forming Brno

*TU, Fac. of Mechanical Eng., Inst, of Material Engineering Brno

**TU, Fac. of Mechanical Eng., Inst, of Mechanic Brno

Key words: formability, forming, failure limit diagrams, tests, FEM simulation, metal flow

This research work contains : a) determination of the formability of cold forming cilin-drical specimens with notches, b) determination of the stress-strain characterization in sheet steel forming, and c) numerical simulation of metal flow during compression and tensile tests.

ad a) Three types of Cr-Ni steels 17 255(A), 17 246(B) and 17 248(C) were used for determination of the failure limits for specimens geometries, frictions condition between specimens and dies and geometry of notches on the specimens, The specimens had an initial height-diameter ratio between 1.2 and 1.7 (d=const.). The friction conditions used were smooth platens and groowed platens.Three types of the failure limit diagrams (FLD) were determined from data of compression tests for specimens with axial v-shaped notches with different depths. The notches were used as surface defects model. Between each step the test specimens were unloaded and the surfaces were examined to detect superficial cracks. Equatorial surface strains were measured until crack initiation in axial (Z) and circumferential (O) directions. Figures 1 and 2 show FLD for A-steel based on the local circumferential strain (LCS) and the global circumferential strain (GCS), respectively. It can be said that the FLD based on the GCS in Fig.l ought to be the most interesting diagram from technological point of view. It illustrates the ductility limit of specimens with common defects such as the notches are. The global failure limit for notched specimens is thus the criterion of the notch sensitivity. If, on the other hand, we want to understand material behaviour up to the failure limit we should study the diagram based on local strains. This diagram illustrates the state of strain experienced by the material element which fractures prefarably (Fig.2). The FLD for all tested steels illustrate different formability of tested steels objectively. The linear relations between LCS and GCS are independent of specimen geometry and friction conditions. The slope of these lines can be used as the criterion for the strain concentration at the certain type of the notch. The values of the strain concentration coefficients are described in Fig.3. The extrapolation exponential function was fitted to the experimental strain paths for all types tested steels. The extrapolated strain paths can be used to calculate the state of stress at the equatorial surface of the specimens and at the notch.

ad b) The aim of this part is to judge the possibility of numer, simulation when analyzing the experiments in the range of large plastic deformation, including the influence of friction in compression test. In the first stage, simulations of tensile and compression tests

845


for different materials were realized using the FEM system ANSYS. The initial information here was thc flow stress curve, and the correlation of simulated curves F - 1, resp. F - h with an experiment was judged, together with correlation of simulated global geometrical characteristics of specimen like contraction, resp. bulging. Measuring of hardnesses in the plane of axially cutted compression test specimen enabled to judge thc correlation of local plastic strain distribution with the computational results (sec Fig.4). As a whole, the results can be declared as satisfactory, approving the possibility of using thc computer modelling as an auxil'ary simulating tool even in thc area of large plastic deformation.

ad c)Thc part of paper presents selected results of investigation of stress-strain curves obtained by the tensile test of the low carbon sheet steels 11 301.21, 11 305.21 and austenitic stainless steel 17 246.1 with different plate thicknesses (0.5 - 1.5 mm). Thc stress-strain curves obtained by measuring are approximated by various functions. There are many approaches towards mathematical definitions of the stress-strain curves of metal materials. We have compared correlation coefficients made by the application of mathematical models given by Hollomon, Ludwik, Voce and Swift. Though thc Hollomon equation is preferred for its simplicity and it has been often used, the best correlation (k = 0.999) between measurement of stress-strain curves and Swift equation was observed. At the same time the influence of thickness on the coefficients of area and normal anisotropy of mechanical properties of low carbon sheet steels has been investigated. In the next year we will arrange a comparison of anisotropy values achieved by tension tests with evaluating of anisotropy by ftTG difi'actometry methods.

This research hus been conducted at the Department of Metal Forming as part of thc research project "Observation of the Material Properties after Plastic Deformation" and has been supported by TU grant No. D 86-93.

846

Section 18

NUCLEAR

ENGINEERING

WORKSHOP 95 NUCLEAR ENGINEERING

ACCELERATOR DRIVEN REACTORS J. Zeman, K. Tuček

ČTU, Fac. of Nucl. Sci. & Phys. Eng., Dept. of Nuclear Reactors V Holešovičkách 2, 180 00 Praha 8

Key words: accelerator driven reactors, waste management, spallation, subcritical reactor, accelerator breeder

The idea of using accelerator in nuclear devices came into existence at the end of 1940's. At that time the idea of elcctronuclear production of fission material by the application of linear accelerator was developed in the Lawrence Laboratory in Livermore within the framework of the secret project MTA (Material testing accelerator). This project was stopped at the beginning of 1950's after discovering rcch uranium ore in the west of the USA [1].

Recently this idea has come back again. Experts of the Los Alamos National Laboratory (LANL) and the scientific team headed by Carlo Rubbia in CERN are working in this field. Apart from releasing nuclear energy this device is also suitable for disposing of nuclear waste.

As there exists no satisfactory solution to thes problem in our Republic and thes way of radioactive waste disposal seems convenient both energeticaly and economicaly, the in-portance of thes project is increasing in some institutions (e.g. ÚJV Rež, FÚ AV CR, SKODA-Jadcrné strojírenství Plzeň and FJFI CVUT). The report [2] was written at the Departement of Physics and some AV CR laboratories, the conclusions of which were read at the symposium "Accelerator driven reactors and nuclear waste management" in Liblice.

Attention to the problem was also paid at the Departement of Nuclear Reactors. Within the framework of resource study [3] the possibility of application of accelerator driven reactor to nuclear waste disposal was studied.

Within the framework of [2] and [3] the working principle and device function are described. Fission of heavy nuclei is the main reaction leading to the release of energy in the same way as in nuclear power plants. This is not ongy caused by the neutrons from the fission, but also by the neutrons produced by spallation reaction,when very energetic protons from efficient accelerator hit the target system. The whole system is subcritical and the energy is realesed only when the accelerator is running. It is clear that only a part of energy which is obtained (as many as 25 %) is necessary to power the accelerator, and the rest of the energy can be supplied to the electrical network.

As primary fuel we can use thorium 232 which is changed by the neutron capture to fission material uranium 233, and which multiplies the number of neutrons originated by the spalation reaction in the target. Use og thorium as fuel would be advantageous also for its much higher world reserves in comparisonw with uranium ore (CERN). Spent fuel containing highly radioactive actinides can be used as primary fuel. These actinides produce additional neutrons under high neutron (luxes. In this accelerator driven nuclear reactor highly radioactive actinides and fission products contained in spent fuel could be transmutated to stable nuclei or nuclei acceptably short life-time (LANL).

The common feature of this way of exploiting nuclear energy is its high technological complexity. Only after gaining experiency with the first devices of this kind generating real energy, it will be possible to check out their cost effectiveness. A high technical complication is a common feature of these ways for using nuclear energy. Their economical advantageous

849


we will be able to test after obtaining of expirience with the first devices of this type produced really energy.

References:

[1] HERMANSKÝ, В.: Podkritické množivé systémy s protonovým urychlovačem pp.71. Jaderná energie, č.2, 1989

[2] JECH, C. - NIEDERLE, J. - POSPÍŠIL, S.: Nové možnosti získáváni jaderné energie a likvidace jaderného odpadu s využitím urychlovačů Symposium "Accelerator driven reactors and nuclear waste management", Liblice, 27.-29. června 1994

[3] TUČEK, K.: Likvidace ra-odpadů transmutací radionuklidů s použitím urychlovačů částic rešeršní práce, KJR FJFI ČVUT Praha, srpen 1994

[4] Proceedings of the International Conference on Reactor Physics and Reactor Computations Tel-Aviv, January 23-26, 1994

This research has been conducted at the Department of Nuclear Reactors

850


MODULAR SYSTEM OF EDUCATIONAL COMPUTER PROGRAMS

"ENERGY SOURCES OF THE EARTH" B. Heřmanský

CTU, Fac. of Nucl. Sci. & Phys. Eng., Dept. of Nuclear Reactors V Holcšovičkách 2, 180 00 Praha 8

Key words: educational computer programs, energy from fossil fuels, renewable energy sources, nuclear energy

In Workshop 93 we presented our first educational program GOLEM designed for the study of nuclear reactor dynamics. This program was based on the simulation of transient processes in pressurized water reactors and has been successfully used for many years in specialized education but only for small number of undergraduate students.

Since good educational computer programs based on interactive approaches are expensive, it sccnis reasonable to concentrate our efforts in computer aided education especially to the programs, which are simple enough to be used for the wide range of students. In the frame of this concept a cooperation with the private software company SIMOPT was established. SIMOPT was founded in 1991 by a group of young enthusiastic engineers with the aim of producing educational programs. Thanks to the financial support of the CEZ, a.s. (Czech energy supplier company), Asca Brown Boveri and Comenius it was possible to start work on new computational programs devoted to energy problems.

At present the following three modules are either distributed or close to completion:

• ATOM 2.1- Nuclear energy • ENERGY FROM FOSSIL FUELS • RENEWABLE ENERGY SOURCES

ATOM 2.1 is the second improved version. The first version was distributed from January 1993 and today about 900 copies have been installed. The experiences from pedagogical use of this module were carefully evaluated and adopted to the new version. To run ATOM 2.1 a minimal configuration PC 286 is necessary. New modules, which arc now close to completion, arc based on the same approach.

The pedagogical exploitation of the educational programs 'Energy Sources of the Earth' can be divided into the following three points:

1. To give the undergraduate students of Technical Universities basic ideas about energy sources, which should be developed in our country.

2. To improve the knowledge of grammar school students (and also teachers) in this field, and awake student's interest to continue the study at Technical University.

3. To help all interested citizens to formulate their private "Energy politic" (opinion) which could help them to choose the best local energy problem solution (probably through some kind of Information Center in the neighborhood of power stations).

851


НПЫ 1НГ fUJCI F W rrWFFI ГЧ.ЙНТ WORKS

circuit II Staan aeneratar

Fig. 1: ATOM 2.1 Menu of vocabulary modes

At present we have good experiences with pedagogical exploitation of the first version of ATOM and limited experiences with the new version. Since the operation of the program is very simple, the program can be run on any current PC computers (starting PC 286) and the price of installation is only 150 Kč (new version), students can use it very easily. For some of them this is their first practical experience with computers.

We have also limited experiences with the second program "Energy from fossil fuels". This program will be probably ready for distribution probably during this year, but we arc trying to test some part of the module in education now (namely in the subject "Introduction to Engineering"). Here we appreciate the value of information about new technologies based on gas-steam cycles, cogeneration of the heat and electricity and "clean coal technologies". Since there is a lack of Czech technical literature which can be used for education of this modern approach to the energy problem solution, suitable educational programs seem to be a good source of information.

After finishing first three modules it can be said that the group of the authors is now well prepared to create the next computational program devoted to "Environmental impact of energy sources". We hope to gather the necessary financial support from different sources which could enable us to adopt a multi-media approach.

852


SOFTWARE RELIABILITY ASPECTS IN DIGITAL CONTROL SYSTEMS

OF NUCLEAR REACTORS K. Matějka, M. Kropík, T. Sejba

CTU, Fac. of Nticl. Sci. Sz Phys. Eng., Dept. of Nuclear Reactors V Holcšovičkách 2, ISO 00 Praha 8

Key words: software reliability, software life cycle, software design, coding, documentation, testing, verification and validation, configuration management, fault tree analysis, failure modes effects, critical analysis

Control systems in the nuclear branch are becoming software intensive. These control systems are safety critical.

The reliability of such systems depends on the reliability of the technical equipment (hardware) and on the software. The nature of the hardware and the software reliability aspects is different. Hardware can fail due to physical stress, time, environmental factors,, etc. Software fails by human design error during development and maintenance of the software. The demands and recommendations for safety critical software in nuclear reactor control systems are given by several international standards, e.g., IECSSO, IEEE P-7-4.3.2. Unfortunately, these standards are unfortunately very general to be a practical guide for developing safety critical software, but some interesting ideas and concepts could be found there.

At first, we shall concentrate on the software life cycle. The software life cycle begins with the requirements for developing the software, which for the nuclear control systems are deduced from the system safety requirements. According to the authors experience, it is one of the most difficult tasks to set correct, complete, traceable and unambiguous requirements. The next step is the design of the software, followed by the coding. Then the software development process continues by testing on the unit, subprogram and program level. Then the software is integrated with the target hardware. The last phase of the software life cycle is the maintenance during operation of the software.

There are some generally accepted practices how to develop more reliable software:

• structured design and coding — to achieve modularity, testability and maintainability, develop units of code that perform exactly one function, maximize local and minimize global variables, develop modules that have related inputs, related outputs, exactly one exit and no high number of branches in logic; fault tolerance, redundancy and diversity, choice of appropriate high level programming language;

• software documentation — the name of the module, location of the module in the software hierarchy, relationships to other modules, history of the module, called by and called to, describing the function of the module in the pseudocode or the Program Descriptive Language, global variables referenced, logic flow diagram, processing performed, used language, compilator and operating system, consistent naming conventions for variables, function names, constants etc.;

853


• software testing — structured, algorithm, logical, functional and performance testing, 'white' box and 'black1 box testing, choice of testing input data, random testing, integration IIVV/SW testing, fault-tree analysis, failure modes effects and critical analysis, proper documentation of the testing process;

t verification and validation (V&V) — show that the target system performs its intended tasks correctly, VfcV should he made in every step of (he software life cycle, independent V&V, documentation of V&V;

• configuration management — documents the method to be used for identifying software product items, controlling and implementing changes;

The common problem when using the computer-based nuclear control system is to quantify the software reliability. The authors know some models for estimating software reliability based on experience by testing and correcting software errors [3] or by an approach similar to statistical physics (<lj. The first methods are usable only in the later stage of the software life cycle, the second method needs many empirical parnmcters, the values of which are very hard (practically impossible) to find. Today there is not a generally accepted approach lo quantify the software reliability yet.

The iibove methods for developing more reliable software are used by the Department of Nuclear Reactors of the FNSPE for developing safety-related software for the up-dated control system of the training nuclear reactor VR-1 SPARROW.

References: [1] Software for Computers in the Safety Systems of Nuclear Power Station I EC 880, Gen

eve, 1986 [2] Standard Criteria for Digital Computers in Safety Systems of Nuclear Power Generating

Stations IEEE P-7-4.3.2., 1094 [3] MATĚJKA, К. - KROPÍK, M. - SEJ BA, Т.: Safety guide SONS, Quality Ensuring of

Software for Control Systems of Nuclear Power Stations Prague 1991 [4] NEUFELDER, A. M: Ensuring Software Reliability Marcel Dckker, Inc., New York,

1993 [5] FERDINAND, A. E.: Systems, Software and Quality Engineering Van Nostrand Rcin-

hold, New York, 1993

This research has been conducted at the Department of Nuclear rectors as part of the research project "Digital Control of Nuclear Research reactors" and has vol been supported by any CTU grunt.

854

C2-35Q50-/Í5 WORKSHOP 95 NUCLEAR ENGINEERING

INCREAS IN THE MAXIMUM POWER OF THE REACTOR VR-1 VRABEC

К. Matějka, A. Kolros, S. Kropš, ti. Sklenka, T, Šejba

CTU, Fac. of Nucl. Sci. & Phys. Eng., Dept. of Nuclear Reactors V llolcšovičkách 2, 180 00 Praha S

Key words: research and training reactors, reactor VR-1, control system, dosimetry, reactor power

The training reactor VR-1 Vrabec became for the first time critical in December 1990. In the first year of operation (1991) main parameters, quality and reliability of different devices were tested.

The reactor VII-1 is an experimental reactor which is characterized by relatively low maximum thermal power. It is practically impossible to measure the amount of heat released in the core by the fission reaction, there arc no measurable temperature changes of the moderator and the fuel. The method for the measurement of thermal power of this reactor should be developed. On the basis of measurement of the neutron flux density in the core and near the core it was found that the maximum thermal power of the reactor varies from 500 W to 700 W. This value depends on the core configuration and the measuring channel detectors positions.

A lot of experiments were developed in the first four years of operation. At present the reactor power docs not permit to conduct any interesting experiments as for example neutron activation analysis of environmental samples. Some other experiments as neutron gas temperature measurement or demonstration of Ccrcnkov irradiation are possible to realize only at the maximum power and not with fully satisfactory results. Therefore the possibility to increase reactor power are being explored. It is obvious that the present high nuclear safety standards will be maintcned at higher power level too.

There are two main problems concerning the reactor VR-l power increase:

• the technical one - performing of necessary changes of the control system and of the core configuration,

• the legislative one - declaration of the required safety level and getting the licence of the State Office for Nuclear Safety

Technically there are two possibilities how to increase the reactor power. The first one is to change the limit values in the control computer program, the second one is to change position of the measuring channel detectors on longer distance from the icactor core. Both options have advantage and disadvantage.A suitable combination of both of them will be probably used.

Many parameters will be also influenced by the reactor power increase. Therefore a spatial experimental program was developed and performed to test all necessary parameters:

• linearity of the RJ 1300 detectors signal • function of independent power protection system • dosimetric situation at different places in the reactor hall, etc.

855


It is proposed that no forced coolant circulation will be necessary, and the reactor is cooled only by natural circulation. The higher power will be still small from the point of view of heat exchange and dissipation.

The safety analysis of maximum project accident was also performed. It was found that the increase of the fission product concentration resulting from the power increase is negligible. The largest amount of fission products, which can be released only in very hypothetical accident case with core melting, is born in the time of accident.

On the basis of experimental results and performed analysis it was concluded that under some restrictions the increase of the reactor VR-1 power is acceptable. The restrictions where precisely formulated and an application was submitted to the State Office for Nuclear Safety.

The latest information about results of licencing will be presented on the workshop presentation.


856

С 235^7/0, WORKSHOP 95 NUCLEAR ENGINEERING

BOILING SIMULATION BY PRESSURE AIR BUBBLES IN THE CORE

OF TRAINING REACTOR VR-1 S. Kropš, Ё. Sklenka

CTU, Fac. of Nucl. Sci. к Phys. Eng., Dcpt. of Nuclear Reactors V Holešovičkách 2, ISO 00 Praha S

Key words: reactor VR-1, training reactor, reactor experiment, boiling simulation, reactivity coefficient, void coefficient

The reactor VR-1 VRABEC is the training nuclear reactor in the FNSPE CTU. It is used for the training of the students and therefore many demonstration experiments were developed and are done by students as a part of laboratory work or as a part of training courses. Most of the experiments are measurements of the basic physical parameters of the reactor core or of fuel used (decay constant of delayed neutron precursors, different methods of reactivity measurement, control rod calibration, basic critical experiment etc.).

One of the important parameters of the core are the reactivity coefficients (reactivity temperature coefficients, reactivity power coefficient, reactivity void coefficient etc.). Good knowledge of these coefficients is necessary for determination of the reactor dynamic stability.

Thermal power of the reactor VR-1 is very low (up to 1 kW). Therefore there are no measurable temperature changes under normal operation, and experimental determination of reactivity coefficients is difficult.

In order to measure the reactivity void coefficient air bubbles instead of steam bubbles were used to simulate boiling.

Some problems had to be solved to obtain correct results:

• homogeneity of the bubble stream • small diameter of the bubbles • determination of the void fraction

An experimental setup was developed to produce bubble stream in the fuel element and in the dummy. In this setup the porous stones (commonly used in aquaristics) are used to make air bubbles.

The determination of the void fraction inside the core is very complicated. Therefore several methods were used to determine the void fraction outside the reactor. The best results were obtained by the measurement of absorption of gamma rays in the mixture of air bubbles and water.

The first time the experiment was concductcd with the dummy in the core position E5. The comparison of the calculation and the experiment results for this case is depicted on Fig. 1. In some range of the void fraction the reactivity void coefficient is positive. It is in agreement with the hypothesis, because the core is locally overmoderated in the dummy. The result of the measurement of the reactivity void coefficient in the four tube fuel element is depicted on Fig. 2. In accordance with the theory the reactivity void coefficient is strongly negative in this case.

857

WORKSHOP 95 NUCLEAR ENGINEERING 0.25 a

0.20

Ž0.15Í

• calculation > measurement

' 5 ?0.10:

0.05-

0.00 - r r 11 M i 11 11 M i M 111 11 ; 11 11 i n I i i 11 ' ' i i i 11 i 0 10 20 30 40

Air fraction («) ^ 0

Fig. 1: The dependence of the reactivity on void fraction in the dummy

- - I I I U I 0.1 0.2 0 3

Flow (l/s)

Fig. 2: The dependence of the reactivity on the void fraction in the fuel clement

The obtained data were used to verify computer codes used for core calculations. It was found that the calculations are in good agreement with the experimental data.

This experiment became a part of a standard experiment set which is offered for the cores for the laboratory exercises.

The experiment is a nice demonstration of one of the most important phenomena which occurs in the reactor core and which has a strong influence on the dynamic behaviour of the nuclear reactor.

References: [1] BURKET, D.: Dutinový koeficient reaktivity Diplomová práce, CVUT-FJFI, 1994 [2] MATĚJKA, K. et al.: školní reaktor VR-1 VRABEC Popis zařízení a první část ex

perimentálních úloh skripta, СVUT-FJFI, 1993 [3] KROPS, S. - SKLENKA, L\: Experiment "Bublinky", metodický návod к provedení

experimentu KJR, listopad 1994

This research has been conducted at the Department of Nuclear Reactors.

858


DETERMINATION OF THE EFFECTIVE NEUTRON TEMPERATURE

IN THE CORE OF THE TRAINING REACTOR VR-1 VRABEC

V. Babulska, A. Kolros, K. Matějka

CTU, Fac. of Nucl. Sci. к Phys, Eng., Dcpt. of Nuclear Reactors V Holcšovičkách 2, ISO 00 Praha 8

Key words: reactor VR-1, training reactor, reactor experiment, neutron temperature, neutron spectrum, lutetium, activation analysis

One of the methods for determining the influence of absorption on the neutron spectrum is to measure the temperature of the neutron gas. At this temperature the Maxwell-Boltzman distribution coresponds better to the deformed neutron distribution under the influence of absorption.

At our workplace, we applycd to work out a method for determining the temperature of the neutron gas in the core of the training reaktor, using integral measurements with the help of lutetium foils. The method is based on the activation measurement with the help of two isotopes of lutetium, the effective cross-section of which has a particular characteristic dependence on the energy (mLu has strong resonance at energy ET = 0.142eV).

Lu as an element is a very suitable material for activation detectors for the following reason: after irradiation of one of the foils and separate evaluation of the indicated 176mLu and ,77Lu activities, as well as the irradiation of the foils in a Cadmium cover we obtained information about the spectral index. Using this arrangment, we can determine the neutron temperature in accordance with Wcstcot's theory:

С =Кд(Тп) + гв(Тп) ш

where: - С/С" is the measured ratio of the activity of 177/,« to that of I76mLi£ - g(Tn) is a function of the neutron's temperature which gives the measure of deviation

of the eiTective cross-section from the l/v law in the thermal region of the neutron spectrum. It is equivalent to the activity of actived 177Lu

- ?• is the spectral index. It expresses the intensity of the intermedial neutrons. For a pure Maxwell spectrum, r — 0.

- s(Tn),s« (T„) arc functions expressing the deviation of the effective cross-section from the l/v law in the intermediate part of the spectrum, for 177Лк and 176mLu respectively

- К is a constant, dependent on the density of the neutrons, on the absolute value of the activation cross-section and the foil thickness. This constant can be eliminated by additional measurement in the previously-known neutron spectrum.

In order to determine the ;• quantity, it is nesessary to measure the cadmium ratio RCD "1/u" detector:

n - 1 + "*(Г„) , . Нс°-л^ыШ ()

859


where ECD is the limited energy of the cadmium and к is the Boltzman constant. The integral measurement were carried out by comparison of the saturated activites

of the ll~' Lu and the U6mLu. The constant /\ was determined by using the graph ratio of the activity of U7Lu to that of 176mLu as a function of the temperature of the thermal column. This graph was measured at the Haiiford laboratories, wliere the calli brat ion of lutetium for measurements of effective neutron temperature was carried out [I]. The values of the function g(Tn) for l7SLu were taken from the VVcstcot tables [2], and the values of the function s(Tn) and sv(Tn) were read from the graph [3]. The determination of г with the help cadmium ratio of ,7sLu cannot be carried out with sulfficicnt precisoin, so it is recommended that ^Cu or 55Л/п used. This was also confirmed by the experiment carried out, in which the 1/u Си detector (purity 99.998%) was additionally irradiated.

In order to calculate the temperature of the neutron gas and the spectral index, a computer code TEPNEU was prepared, which enabled the calculation of the above parameters. The program used the iteration method.

The experimental results of the data yielded cadmium ratios for Lu in the cell J34 (reflector) 2.19 ± 0.01 and 1.20 ± 0.06 in the cell /S3 (core). The cadmium ratio of a thin "1/u" detector ih the same position was 31 ± 1 and 9 ± 2, respectively. The effective neutron temperature in JS3 (measured in the centre of the core along its height) was 452 ± 20 К and in the reflector (cell B4) it was 413 ± 20 K.

As expected, and in accordance with the measurements, the thermal spectrum in the school reactor is brittle and the energy of the neutrons is high.

Applying this method of measurement with the help of lutctium foils in the reactor VR-1 VRABEC, information was obtained concerning the nature of the: neutron spectrum in the reactor core A3.G and its environment.

References: [1] SCHMID, L. С - STINSON, VV. P.: Calibration of Lutelium for Measurements of

Effective Neutron Temperatures Nucl.Sci.Eng. 7.477 (1960) [2] VVESTCOTT, С. Н. - ROY, D. A.: Effective Cross-Section Values for Moderated Ther

mal Reactor Spectra CRRP-S62,1964 [3] BECKURTS, K. J. - VVIRTZ, K.: Neutron Physics Springer-Verlag,1964


860


TREATMENT OF SPENT COMPOSITE ION-EXCHANGERS

FOR FINAL DISPOSAL F. Sebesta, J. John, A. Motl, J. Steinerová

CTU, Fac. of Nucl. Sci. & Phys. Eng., Dcpt. of Nuclear Chemistry Břehová 7, 115 19 Praha 1 - Stare Město

Key words: composite ion-exchangers, final disposal, cementation, vitrification

Characteristics of composite absorbers composed of powdered inorganic ion-exchangers (active component) and binding polymer (polyacrylonitrilc - PAN) have been given earlier [1,2]. Reviews of possible applications of these composite absorbers for treatment of liquid radioactive waste indicate their prosperousness for development of new advanced technologies [3,4]. Their more rapid application on a broader scale was limited by lack of information on possibilities of treatment (solidification) of spent absorbers for final disposal in nuclear waste repositories.

The aim of this study was to verify the possibility of cementation and/or vitrification of selected spent composite absorbers for their final disposal. The experiments performed were directed towards determination of the most important parameters of the resulting solidified materials - optimum filling of composite absorbers, mechanical stability and leachability.

The primary process that has been considered for treatment of composite absorbers for their final disposal is immobilization in cement. TiO-PAN, Ba(Ca)SO.(-PAN, KNiFC-PAN and NiFC-PAN absorbers were selected for testing. In the tests performed properties of cement samples loaded with increasing amounts of composite absorbers, and water resistance after soaking for 1 week, were studied by measuring their compressive strength. In. addition the influence of clinoptilolite admixtures to cement mix and freeze/thaw or soak/dry cycling to the quality of cement samples was studied.

From the results of tests performed it can be concluded that loading of cement mix with dry composite absorber up to 5 - 9 % (w/w) is acceptable [5]. Maximum loading depends on the type of composite absorber and its grain size. Admixtures of clinoptilolite improve the compressive strength of the resulting cement samples. Compressive strength of the resulting cemented samples ranged from 10 to 34 MPa. No significant deterioration of the quality of composite absorber - cement product with admixtures of clinoptilolite was observed after repeated freeze/thaw or soak/dry cycles.

Leachability of 137Cs has been followed in long-term tests of samples of cemented NiFC-PAN absorber, because this absorber is most prospective for full-scale application. Leachability of 137Cs is followed from samples of spent absorber solidified in pure cement and/or cement with admixtures of clinoptilolite. These long-term tests have not yet been finished.

Because of the high efficiency and selectivity of composite absorbers, the volume of treated waste can reach up to 104 to 10s times the bed volume of the absorber (concentration factor 104 - 105). In such applications, namely when treating higher level waste, spent composite absorbers represent high level waste. Immobilization of such materials in cement may not be acceptable and/or safe enough.

861


The possibility of vitrifying NiFC-PAN absorber was tested in trial experiments [5]. Dried NiFC-PAN absorber was mixed with low-melting glass frit in different, ratios and melted in porcelain crucibles. Viscosity, visual quality and liydrolytic resistance of samples were examined. Melts produced from mixtures containing 10 % (w/w) of absorber were highly viscous, it was hardly possible to pour them from the crucible. When only 5 % (w/w) of dried absorber was added to the mixture, the melt could be easily poured from the crucible and the melt was transparent and homogeneous.

Hydrolytic resistance of the product was tested by leaching 1 g of crushed glass specimen (0.3 - 0.5 mm, 5 % of dried absorber) in 50 ml of distilled water for 24 hours. Electrical conductivity of the leach ranged from 6 to S /(S.cm-1. Following the criteria for fast preliminary evaluation it is assumed that vitrified materials which yield hydrolytic resistance lower than 20 /iS.cm~l in such tests are suitable for long term storage as high level waste.

From the results achieved so far it can be concluded that both cementation and vitrification may be used for the final treatment of spent, composite absorbers for their disposal in radioactive waste repositories [3,5]. The compressive strength of cemented samples is several times higher than the acceptance limit (5 MPa) of the radioactive waste repository at Dukovany. If the leaching tests will yield satisfactory results, cementation may be applied for low to medium activity spent composite absorbers. For high activity spent composite absorbers the experiments performed with NiFC-PAN absorber proved that the presence of PAN binding polymer does not disqualify composite absorbers from final treatment by vitrification. In all cases when the active component (inorganic ion-exchanger) is vitrificable, the corresponding PAN-bascd composite absorber may also be solidified by vitrification.

References:

[1] SEBESTA, F. - MOTL, A. - JOHN,.).: Composite Ion-Exchangers, their Development and Use Workshop '92, Part. 13, Sect. 1, pp. 25 - 26, CTU Prague, 1992

[2] SEBESTA, F. - MOTL, A. - JOHN, J. ct al.: Composite Ion-Exchangers and their Possible Use in Treatment of Low/Intermediate Level Liquid Radioactive Wastes In: Proc. 1993 Int. Conf. Nucl, Wastes Management and Environmental Remediation, Prague, September 5 -11 , 1993; Vol. 3, pp. 871 - S7S, ASME, New York, 1993

[3] ŠEBESTA, F. - JOHN, J. - MOTL, A.: Inorganic-Organic Composite Absorbers with Polyacnjlonitrile Binding Matrix - Possible Applications In: Proc. SPECTRUM '94 Nuclear and Hazardous Waste Management International Topical Meeting, Atlanta, GA, August 14 - 18, 1994; Vol. 2, ANS, La Grange Park, Illinois 1994, pp. S5G - 8C1

[4] SEBESTA, F. - JOHN, J. - MOTL, A.: Separation and Concentration of Contaminants Using Inorganic-Organic Composite Absorbers In: Proc. BUDAPEST'94 Second International Symposium and Exhibition on Environmental Contamination in Central and Eastern Europe, Budapest, September 20 - 2 3 , 1994, in press

[5] SEBESTA, F.-JOHN, J.: Development and Testing of Composite Absorbers. Research Report for Los Alamos National Laboratory, Faculty of Nuclear Sciences and Physical Engineering, CTU Prague, April 1994, 17 pp.

TVu's research has been conducted at the Department of Nuclear Chemistry as part of the research project "Treatment of Spent Composite I on-Exchangers for Final Disposal" and has been supported by CTU grant No. 482U,.

S62

Section 19

TRANSPORT

ENGINEERING

WORKSHOP 95 TRANSPORT ENGINEERING

METHODOLOGY AND DESIGN OF HIGH RELIABLE

TRANSPORTATION SYSTEMS P. Moos, J. Vlček

CTU, Fac. of Transportation Sci., Dept. of Automation and Transportation Control Konviktská 20, 110 00 Praha l

Key words: transportation network, structural sensitivity, ultrastability

The main research aim in the field of ultrareliability is extremal stability of parameters in the transportation and telecommunication network. The transportation activities arc then considered as processes carried by a transportation system through the technical infrastructure of a network. The stability of the processes is strongly determined by the stability of quality parameters of the given path. Our research has been focused on the analysis of structural sensitivity definition and its evaluation which provides the information about the influence of structural and morphological properties of networks in a transportation process.

Introduction. Our definition of structural sensitivity arises from the graph description where the graph transfer function T(p„ *,) which belongs to the graph structure should be evaluated. The evaluation is performed in the time instant Í,-, if we consider an element of a network with all the components pj of the set {;?} tied in the stable stage but one component />,-, i ф j is varying. Our contribution to this topic arises in devising a so called mutual sensitivities where the coupling among parameters and the changes of one particular element produce the change of parameters of another element. The optimal system design is consequently based on the mutual tolerances compensation in characteristics of the resulting system.

Structural sensitivity and transient table. The concept of structural sensitivity and mutual sensitivities is applied in the case of the analysis of a heterogenous system. It starts from the formulation of absolute stability of the class of the systems in a given state variable space then it formulates the class of the ultraslable process of one system. The next part of our concept is given by the theory of transient functions. The final set of possible stages of the elements {/>} of a network forms the fundamental basis of the ultrastability of an arbitrary heterogenous network. The stages are described by the symbols a, b,c,d,... Then the events causing the transients in the network are described by the transient table — see Table 1.

Concluding postulates. We define the ultrastablc heterogenous network by two postulates. The first and stronger postulate requires the finite, conservative heterogenous state space of identified symbols. The second, and rather weaker postulate is a statement about the evolution of {q}, i.e. the evolution in the quality of events initiated by the transients in the state space.

865

WORKSHOP 95 TRANSPORT ENGINEERS

Tab. 1: Transient table

events I

symbols

'« Hn) «Ы e{pi) d(Pi)

с(л.) c{pi) c(Pi) c(pi)

e(;>.) d(pi) Hpi) «(/'.)

It consequently means that:

• if q has the value in the finite set a network is moving through the finite set of qualities of events and the stronger postulate is satisfied,

• if the set of qualities of events is an open and unlimited one, then it represents the changes which decrease the stability of a heterogenous network.

This approach to the ullraslabilily of the heterogenous network enables us to express the behaviour of the transportation or telecommunication network. It includes the concept of a deterministic chaos in possible transients and it provides an access to the recognition of a possible bifurcation in the process.

References: [1] VLCEK, J.: Inženýrská informatika, Vydavatelství ČVUT , Praha 1993. [2] MOOS, P.: Informační technologie, Vydavatelství ČVUT, Praha 1993. [3] MOOS, P.: Vybrané metody modelování jako součást informačních technologií pro

charakterizaci slauxl a procesů v systémech, Habilitační práce, ČVUT, Praha 199<1.

This research has been conducted at the Department of Automation and Transportation Control as part of the research project "Theory and Design of High Reliable Systems" which is supported by grant No. 101/93/0430 of GACR.

866


SUPPORT OF TRANSPORTATION MANAGEMENT

BY INFORMATION SYSTEMS

P. Moos

CTU, Fac. of Transportation Sci., Dept. of Automation and Transportation Control Konviklská 20, 110 UO Praha 1

Key words: information management, transportation technology, information, knowledge

Modern managers in transportation should understand how to use new tools at their disposal, and, in particular, the tools for handling information - the most fundamental of all basic resources. Thus, the issues are much more complex than simply consideration of cost reduction through automation. It is not simply about replacing human effort by machines, nor only about handling very high-value complex transactions, not about storing large volumes of data, although all these functions will take place within an information network. It is not only about automating project of business processes, but it is about communicating, that is, transferring information between people and between project and business processes. On these attributes of informatics is based the efFectivncs of new integrated transportation technologies.

Information management, using information technology as the tool, is all about the efficient running of the projects and, in its final form, in business. Today, this means that all forms of electronic, optical or optoelectronic storage, retrieval, processing, transmission and presentation of information should be used in a cost-effective way to support project design and business needs in the transformation process within a transportation policy.

All organisations are information systems. Information is the primary resource available to man. It is that resource from which, ultimately, all others flow. Even the supply of food, man's most important physical resource, depends on the accumulation of data.

These data are then ordered into patterns of linked and correlated facts that are termed informations — see Fig. 1 where the information chain is shown.

There are no doubts that the contemporary technical infrastructure of information systems plays a grate role in the relations among entities in the complex ecosystem. This infrastructure has now a new quality for its globalisation through developed communication possibilities and computer networks, which are interconnected through out all the world. The communication means, computers, local and large public networks, distributed and centralized databases create an information environment, which demands a similar responsible approach to its quality, as the physical environment. In that sense the studies of information ecology are very necessary.

867


DATA

Data 1 Data 2

Data n

Fig. h Data —• Information

—• INFORMATION

Knowledge

—» KNOWLEDGE

Derived data

past

Rides

present future

time

References: [1] MOOS, P.: The role of information science in sustainable growth, The International

Seminar on Technology Assessment and Sustainable Growth, Wiena 1993. [2] MOOS, P.: Informační technologie, Vydavatelství ČVUT, Praha 1993 [3] MOOS, P.: Computer Technology - Environmental and Social Impacts, (Invited paper)

Postgraduate Seminar, University of Valencia, Spain 1994.

This research has been conducted at the Department of Automation and Transportation Control as part of the research project "Science, Technology and Society" and has been supported by TEMPUS JEP grant No. 2040-93/3.

868


DISTRIBUTED MONITORING AND ROAD TRAFFIC CONTROL

P. Moos, L. Lhotská*, M. Vlček

CTU, Fac. of Transportation Sci., Dcpt. of Automation and Transportation Control Konviktská 20, 100 00 Praha l

*CTU, Fac. of Electrical Eng., Dcpt. of Control Engineering Technická 2, 166 27 Praha 6

Key words: traffic flow simulation, micromodelling, traffic macromodel

The main aim of the research is to find the way how to optimize the processes representing the traffic flow in the heavy loaded areas in regions of the Czech Republic. The traffic flow simulation component grew out of the macroparticle simulation model MPSM [1] , originally developed for a simulation of single highway commuter traffic. This model simulated traffic on a discrete set of segments in a one-pass manner, moving vehicles from each segment to its downstream segments. The approach has been extended to simulate a highway network with intersections which requires the modelling of capacity-constrained vehicle location into each segment from segments incident on its upstream node. It is possible to simulate eacli physical link in the network using muiltiple segments to capture traffic flow dynamics more accurately.

The approach to the micromodelling. By micromodel we will call the model which reflects only a limited part of the road network described by the equation of continuity

dq(x,t) dp(a;l) -чг+-цг=дЫ]' (1)

where q(x, i) is the flow [vehicles/hour], p(.v, t) is density [vehicles/km] and g(x,t) is the net loading factor. In conventional models they are usually coupled with a speed-density relationship. Following equation holds

(j{x,t) = vp(x,t), (2)

where v is the average speed [km/hour].

Advanced Information Processing (AIP) and macromodelling. As it was verified by practice it is quite difficult to reach a solution through the mathematical algorithms only. The difficulty arises in anticipating any possible network traffic anomaly in the size of the macromodel. The AIP techniques seem to be well fitted for methodology implementation. Heuristic rules are needed to complete the knowledge and the sensitivity models of the network graphs are to be developed. The structural sensitivity concept has been derived during the first year of our research activity in this field. This new sensitivity concept provides the possibility to evaluate different variation of path if the load is varying in time.

869


Fig. 1: О represents a terminal node, I I represents a transit node.

In the road network it is possible to distinguish 3 types of the connections - branches

• connection between the terminal node and transit node • connection between any two transit nodes • direct connection between the terminal nodes

If the transit nodes are identified with the border crossings the abovementioned simulation can help to find the optimal choice of the transit point and corresponding time of the transit.

References:

[1] CHANG, G. - MAHMASSANI, II. S. - HERMAN, It.: /1 Alacropartide Traffic Simulation Model to Investigate Peak-Period Commuter Dccission Dynamics, Transportation Reascarch Record, No. 1005, TRR - 19S5, pp. 107-120.

[2] MAÍIÍK, V. - ŠTĚPÁNKOVÁ, O. - TRAPPL, R. - (cds.): Advanced Topics in Artificial Intelligence, LNAI No. 017, Springer Vcrlag, Berlin-Heidelberg, 1992.

This research has been conducted at the Department of Automation and Transportation Control as part of the research project "Distributed Monitoring and Traffic Control in Czech Republic" and has been supported by CTU grant No. 37-01-9.

870


TRANSPORT MODEL OF OVERSEAS COAL

B. Duchoií, M. Hobza

CTU, Fac. of Transportation Sci., Dept. of Transport Economics and Management Konviktská 20, НО 00 Praha l

Key words: emission, EU Directive, energy and transport technologies, overseas coal, transport model

Current Situation. Most European countries, including the Czech Republic, arc under pressure of environmental factors concerning of the combustion process. For many years the attention has been focused on the acid rain issue (SOi and N\Oy emissions). Now, a more serious problem must be taken into consideration: the CO2 emission as a important factor causing the greenhouse effect.

The European Union introduced a Directive (19S4) supplemented by other Acts (19S8) to reduce SO2 and NxOy as a main emissions from the industrial and energy plants.

The limitation forces new technical solutions like Flue Gas Desulphurisation and Selective Catalitic Reduction, Integrated Gasification Combined Cycle System and other cleaner combustion of coal. But it is worth noting that the cleaner technologies are very expensive.

A more serious situation is connected with COi emission . The problem is in fact that coal with a low or zero sulphur content produces CO2 emissions and for CO-z limitation it would be necessary to use some of the coal gasification technologies (better rate // : C) but with a high capital cost.

EU Solution. The above mentioned problems could influence the coal market and transport cost. Coal has been the most important energy factor in Europe. As time passed by the production cost of European producers was increasing due to acid rain and the greenhouse effect, labour demand, depletion of coal deposits and safety standards.

At the same time the low sulphur content coal was discovered as a new energy resource so that the seaborn coal trade increased and its price became more competitive. Due to the European production the price has been decreasing steadily and coal from overseas countries covers the energy requirements.

The Goals of Future Research Work.

1. The Czech Republic has experienced the similar problems as the Western Countries. For the next decision process would be very interesting to prove the same way: the import of overseas coal because of a very low sulphure content, low production cost and suitable transport cost to the European ports. Such an approach should be introduced at the model solution.

2. We may consider the following ports which appear as a suitable inputs into the Czech Republic : Hamburg, Rostock, Štětin, Rotterdam. The transport from these points will be provided by railway and river traffic as two possible technology alternatives.

3. The coal transport can be provided through the set of traffic ways. The optimal traffic connection will be chosen under condition the total least cost of transport.

871


4. For the choice of the suitable alternatives of the simulation model will be created so that it would be possible to change the technical, chemical, mining, traffic and economic conditions and through these changes to model various variants of solution.

This research is conducted at the Department of Transport Economics and Management and has not been supported by any grant.

872


THEORETICAL MODEL FOR TRAFFIC VOLUME

M. Hála, P. Karličky*

CTU, Fac. of Civil Eng., Dcpt. of Mathematics Thákurova 7, 166 29 Praha 6

*CTU, Рас. of Civil Eng., Dcpt. of Highway Engineering Thákurova 7, 166 29 Praha 6

Key words: traffic volume, statistical model, polynomial regression

Searching for the theoretical distibution of the traffic volume was one partial problem met in the scientific research conducted at the Dcpt. of Highway Engineering. The examined data consisted of 49 samples of hourly traffic intenzitics measured during one day. The days and localities of measurements were different (Fridays and weekends were excluded, 34 samples were taken on highways and the rest on other communications). Moreover, each sample included, apart from the total intcnzitics, the intenzities of passenger vehicles, lorries or busses and long vehicles. For the details sec [1].

The problem was to estimate the theoretical distribution of the traffic intenzity, i.e. to estimate the probability density function of the random viiriable denoting the moment of the entrance of the vehicle.

The relative frequencies for each sample and for each kind of vehicle were computed and compared. Some empirical conclusions were drawn:

• The course of the relative frequencies for various kinds of vehicles is different (in the case of passenger vehicles we got two peaks, in other cases one peak).

• The difference between highways and other communications doesn't seem to be of great importance.

• Because of the dominating character of the passenger vehicles the total frequencies have a similar course as the passenger ones.

We have concentrated on the passenger vehicles on highways. The average relative frequencies were computed and a fitting curve was searched using polynomial regression. Only the polynomial of the 9-th degree fitted the average frequencies with sufficient quality— the coefficient of determination was nearly 98.9%. After dividing this polynomial by its integral (so as to get the probability density function) we got the function:

f(t) = 4.3925E-101° - 5.547E-9 tB + 2.9649E-6i7 - 8.728E-5 Í6 + 1.5425E-3 <5 --0.01G74 /'' + 0.1096113 - 0.4096312 + 0.790931 - 0.60287.

The plot of the average relative frequencies together with the fitting density is shown in Figure 1. Note that for better quality of fitting we assumed the time passing from 2 a.m. till 2 a.m. because the traffic volume reached its minimum between 2 and 3 a.m.

873

WORKSHOP 95 TRANSPORT ENGIN'EERING

average relative frequency estirnated density

1* 15 28

time (hours)

25 зе

Fig. 1: Plot of average relative frequencies and the estimated density

The derived model was tested back on all 34 highway samples with satisfactory results. Chi-square tests for distribution fitting were used.

Let us finally notice that searching for the density as a combination of two normal distributions is also possible. In this case (which seems to be more natural from the probabilistic point of view) we could get a function depending on fewer parameters. The method of finding it and testing should be the object of further research so as to promote the extension of the research to other kinds of vehicles and communications.

References: [1] DLOUHÁ, E. - HÁLA, M. - KARLIČKY, P.

ničního provozu a další: Analýza variací intenzit sil-

This research has been conducted at the Department of Highway Engineering as part of the research project "The possibility for more precise computations of one day's traffic volume from short-term measurements" and has been supported by CTU grant No. 2052.

874


IMPROVEMENT OF RELIABILITY AND SECURITY OF ROADS

F. Lehovec, P. Karličky, J. Volf, F. Luxemburk, P. Jirava, L. Vébr, P. Slabý, M. Feitl

CTU, Fac. of Civil Eng., Dept. of Highway Engineering Thákurova 7, 166 29 Praha 6

Key words: pavement design, edge ciTcct modelling, traffic calming

Our research is divided into a three parts : pavement design, edge effect modelling and traffic calming.

The main problem with pavement design lies in the differences between the theoretical suppositions and the real conditions. This especially coi.ccrns the behaviour of materials, traffic loading, the variability of the climatic conditions and the water regime under under the ground.

It is very difficult or even impossible to simplify properly all the effects which have an influence on the design of a flexible pavement. This is manifested in some applications of the present design method. If an integrated section of a construction is treated, some illogical solutions appear. One of the reasons for it is that the material characteristics used for the design are not real ones. They differ due to various causes. We are unable to establish some design parameters cither in the laboratory or on site. That is why we recommend simplifying theoretical solutions and minimising the number of material parameters entering the computation.

One possibility for simplification in the design of pavements is to check it for one temperature regime only (for example for medium yearly temperature). This would reduce the number of parameters for mathematical solution from 15 to 5. If we consider that any of these characteristics are established in a inaccurate way, the proposed reduction will decrease the risk of error. This reasoning led us to modify the computation method in cooperation with B. Novotný from the Klokncr Institute of CTU. The pavement is checked only for one average yearly design period.

Verification of this mathematical model was carried out on a complete group of pavement structures, which were divided into 6 classes according to the traffic load. We considered an imperfect interaction at the point of contact between different layers especially between the cemented and the non-cemented ones.

The second subject of our research was evaluation of the edge effect of the flexible pavement, since most of the damage frequently occurs on the outward edge of the traffic lane. Considering that normal multilayer computing models cannot simulate discontinuities in layers, the finite element method was used.

Results have shown that the edge effect appears even after only in 600 mm from the edge of pavement. The highest effect occurs when the edges of the traffic load area and of the pavement are in the same location. The increase in the deflection of the slab edge varies between 140 and 200%. The increase in the stress varies between 30 and 90%.

With respect to load repetition and fatigue, the edge effect can have quite a considerable influence on pavement design. The edge effect shows itself much more if the axle load is higher, if the к value under the pavement boundary is lower or if there is some unevenness

875


in the pavement edge and a dynamic effect occurs. Even though the traffic docs not load on the edge very often, it results in the a big decrease in the bearing capacity with the emergence of damage at the boundary and its later propagation. The edge effect explains existing damaged pavement edges.

The third part of our research concerned traffic calming, The need for traffic calming is related to the increase in the number of the vehicles and protection of the environment. There are some zones for cyclists or pedestrians in our towns. However in some European countries local area traffic calming is used.

Traffic calming represents a new global approach to the problem. This means a combination of traffic management and regulation, traffic signs and one-way roads with some physical components such as speed humps, shifting of passage from side to side (chicane) and change of the pavement surface etc. Traffic calming helps to organise the distribution of traffic in the road network and reduces the use of roads where heavy traffic is undesirable. This creates better conditions for the safe circulation of pedestrians, handicapped persons, cyclists and a better environment for all inhabitants.

Our research focused on the following themes:

• definition of the term "local area traffic calming", evaluation of its contribution, • legal conditions for its verification and broader application, • project studies of local area calming (in the area of Letná and in the part of Karlín), • analyse of volumes and velocities in the area of Letná.

The laboratory part of our research concerned the testing of a large number of rheolog-ical properties (modulus of rigidity, dynamic modulus, creep, fatigue) of asphalt mixes used for construction and reparation of the road network.

This research has been conducted at the Department of Highway Engineering as part of the research project "Improvement of Reliability and Security of Roads" and has been supported by CTU grant No. 181 52.

876


THE POSSIBILITY FOR MORE PRECISE COMPUTATIONS

OF ONE DAY TRAFFIC VOLUME FROM SHORT-TERM MEASUREMENTS

P. Karličky, Т. Vacek, M. Hála

CTU, Fac. of Civil Eng., Dept. of Highway Engineering Thákurova 7, 166 29 Praha 6

Key words: highway engineering, traffic hourly variation, traffic modelling

Knowledge of the volume of traffic in a road network has a basic importance for highway engineering. There is a large variation in the volume of vehicles through time due to life's rhythm and to the territorial non-uniformity of work and recreation activities during the day, week and year. This variation has a more or less periodical character. Thus knowledge of the rules goverping the distribution of traffic variation is a prerequisite for making a reliable description of the present state and for describing future developments in traffic volume. Since long-term observation is difficult to assure (due to the high cost and because reliable results are obtained only with perfect electronic equipment), it is carried out only at a limited number of observation points and with various levels of precision. Thus for the main part of the road network it is necessary to base computations on short-term measurements which are transformed into daily volumes on the basis of knowledge about the corresponding traffic variation type.

Results from the first year of research will be described. These include the method of analysis and the main conclusions. The basis for the analysis:

Some basic data íegarding the hour volume of traffic were obtained by the Road Fund Administration using a Golden River Marksman Classifier at 8 points equipped by two induction loops installed on the pavement. This equipment evaluates vehicle type automatically according to its length and stores the data in a memory.

To make use of this data for our problem it was classified according to data from a large scale surveys of vehicle kinds into three basic types

0-500 cm passenger cars 500-1200 cm trucks and buses 1200-2200 cm trucks with trailers

The first task was to create a data file for analysis, which was composed of the data obtained over 24 hours of the 49 working days (Monday-Thursday) on 8 roads within the 1st category (1/3, 1/5, 1/8, 1/10, 1/38) and 2nd category (11/101, 11/102, 11/333) in the period of measurements from July 1989 to October 1991.

Range of volume: 1 900-11 300 veh/24 hours Range of composition: 10-29% trucks Range of composition: 1-22% trucks with trailers

877


The results show that there is a relatively large spectrum in the traffic volume and in its composition which corresponds approximately to a value a little higher than the average traffic load of those road categories on working days at present.

Findings from the analysis of traffic hourly variation: A. Multiple regression analysis showed an important correlation between the night

traffic volume (from 21.00 p.m. to 5.00 a.m.) of different vehicle types and the total daily traffic volume as well as the percentage of trucks and trailers.

B. No important differences appeared in the distribution of the relative frequencies of daily traffic volumes among different observing points and measurements, if the type of vehicles is also considered , even though the measurements are not regularly distributed throughout the whole year and even though there were important changes in road transport during observation period (19S9-1991).

C. The data file of daily traffic volumes of is relatively uniform for each day of the week from Monday to Thursday. No important differences between those days has been found.

D. The distribution of traffic variations for each type of vehicle is different. This concerns especially the two-peaks in the distribution of the relative frequency of passenger cars. A model for this distribution (theoretical density of probabilit}' was obtained considering a polynomial of the 9th degree) is presented in a separate article in the section of mathematics by Hála.

E. There are large differences in the traffic volumes if the data is divided into road categories, but the relative frequencies vary only slightly. Some minor differences for the class "trucks with trailers" are further analysed.

At present we are analysing the use of a method with a moving average at the level of variously formulated short-term samples. The possibility of a comparison between the analysed data file with the data from measurements made in 1994 is considered. Some of the data provided by Kozák from the Czech Ecological Institute (grant Ministry of Environment GA/320S/93) in exchange for results demonstrating the dominant position of the relative distribution of traffic variation for 24 hours classified according to their type.

References: [1] KARLIČKY, P.: Report about State of the AH in Average Hourly Variation Research

for Highway Fund Administration, J99J

This research has been conducted at the Department of Highway Engineering as part of the research project "The possibility for more precise computations of one day traffic volume from short-term measurements" and has been supported by (he Faculty of Civil Engineering CTU grant No. 2052.

878


FATIGUE STRENGTH MODELLING AND ITS CONSEQUENCES FOR PAVEMENT DESIGN

J. Volf

CTU, Fac. of Civil Eng., Dcpt. of Highway Engineering Thákurova 7, 166 29 Prahu 6

Key words: pavement design, pavement modelling, fatigue strength model

The current algorithm for the Czech design method of assessment of the fatigue strength of asphalt pavements is at variance with its very character. The consequence of this system error is the fact that we arc "cheating" the asphalt pavement already during the design phase. Some endeavours at refining the model of fatigue strength exploitation have only further influenced an increase in this paradox.

In this paper we attempt to devise a procedure for eliminating this internal discrepancy within the design system. The procedure presented proves that the pavements designed so far have been "undersized", at least from a theoretical point of view. The same situation takes place during the design of multiphase asphalt pavements. However in this particular case, the mentioned paradox acquires unpardonable dimensions. The presented paper firstly acquaints the reader with the mentioned approaches, then explains the substance of its internal discrepancy and then compares individual designs using examples.

The designs described further differ diametrically in the approach to the fundamental problem, the means of when and how to formulate the consequences of the fact that the pavement is loaded in three different temperature regimes producing different responses in the road structure.

The existing design method supposes that the fatigue strength of the material in the critical layer is controlled by the well known relation through a not very comprehensible quantity, through the coefficient of utilization. The different cfTects of fatigue in the different temperature regimes is expressed by means of a homogenization of the variable fatigue process. In this way we actually prescribe how the material should behave, although its fatigue resistance is explicitly determined by the magnitude of its fatigue coefficients and strength.

In the main equation this fact is however successfully ignored. Thus we admit that in the critical summer period a considerably higher number than the designed number of axle repetitions may be effected: more than the material is capable of sustaining, to say nothing of the fact that at certain parts, the fatigue strength must be unconditionally reserved for the remaining two temperature periods. The performance of a pavement is the number of axle load repetitions per unit magnitude of the coefficient of utilization.

The characteristic feature of the new approach lies in the endeavour to characterize in a model the gradual change of the climatic design conditions and load in the cycle of years. The coefficient of utilization is obtained by the summation of these increments for every temperature period of an individual year and it must not exceed the value of the design period in years. The performance is represented by the successive sum of these elements at

879


the moment when the coefficient of utilization attains the value of the design period. The computation is laborious.

This concept of design represents a combination of the static find the dynamic solutions regarding the changing conditions and to the response of the structure in the framework of the design period. The effect of fatigue is summated or varies in the course of the design period. The break-up of the design period into shorter sections, if we tolerate these hybrid assumptions, is debatable, to say the least. The results obtained by this procedure "economize" on material consumption, and this means that the authors and advocates of this design method consider our existing pavements "oversized".

If the fatigue resistance of the material is predetermined by means of its design characteristics, it is the very magnitude of the stress that is decisive for the maximum permissible number of repetive loadings in the climatic conditions. This equation follows out of the condition of the failure of the material in one period, when the fatigue strength drops to the radial stress level.

The proposed relation must hold to ensure that the material is not damaged in the individual climatic conditions. That means the actual number of load repetition cannot attain its maximum for each period. It is possible to use the principle of linear superposition of relative deteriorations to ensure the necessary portion of fatigue strength for all periods.

Л comparison of asphalt pavement performances according to these three methods reveals the big differences. The undcrsizing of the pavement caused by the summer paradox considered using the number of load repetitions varies between 60% to 1000% and more. The undersizing expressed in the thickness represents a difference of between 15 to 70 mm of top layer.

The presented results show that the paradoxes burdening the Czech design method for asphalt pavements and its modification for the multiphase design can be eliminated by application of the linear superposition principle of relative deterioration during the procedure exploiting fatigue strength. These expressions arc characterized by their methodological purity and fidelity to all assumptions on which our design method is based.

This 7-esearch has been conducted at the Department of Highway Engineering as pari of the research project "Alternative Deterioration Models of Road Structures" and hat, been supported by the Faculty of Civil Engineering of CTU grant /Yo. 2051,.

880


NEW POSSIBILITIES FOR MODIFICATION OF ASPHALT

BINDERS AND MIXES F. Luxemburk, B. Klobouček

CTU, Fac. of Civil Eng., Dcpt. of Highway Engineering Thákurova 7, 166 29 Praha 6

Key words: modified asphalt, thermoplastic rubber SBS

The need for an increase in the pavement life-time for extremely loaded flexible pavement constructions is closely linked to interest in possibilities for modification of asphalt binders and mixes. The Department of Road Structures has been at work on this problem for many years with some successes. The results of such studies have been published starting at least from 195S. Asphalt modification have been fully applied in many cases with construction practice.

In the light of previous knowledge and due to the recent developments in both our country and abroad, we have concentrated this part of the research on the method of modification using

• thermoplastic rubber SBS (styrene-butadieue-styrene) and • a concentrate of reclaimed rubber MODAS PD 2.

Both the structural and chemical action of the modified composition of asphalt and the bond of the asphalt with the modifying additives are well understood. An appropriate method of fabrication has to be chosen according to the specific use of the modified binder and to the conditions of the application. In addition both the influence of temperature and the time of homogeiiisation during fabrication is not negligible.

The modification of asphalt composition by using thermoplastic rubber has a couple of indisputable advantages. However it docs not permit the long term action of a temperature higher than 180°C since continuous degradation of the additives takes place. Thus the temperature of 1S0°C is judged as the upper limit for the admissible temperature of homogenisation.

We focused on the problem of whether this limitation is to be strictly respected or if it is possible to use a shorter time action of a higher temperature for reasonable disturbance of the elastomer structure. This would facilitate its bonding with the asphalt components and produce an improvement in the rhcological properties of the binder as well as a substantial reduction of fabrication time and a decrease in production costs. The verification of this new method modification has been carried out using a common mix of asphalt AP 80 and thermoplastic rubber SBS of the Cariflex type TR 1101 M of Shell which has well-known properties. We used 5, 7, 10, 12 and 14 % of SBS. The influence of the temperature and time of homogenisation for modified asphalt with 12 % of TR 1101 M is apparent from these results.

' An increase of the temperature within certain time limit has a favourable influence on the homogenisation and reduces the fabrication cost. The starting fabrication temperature

881

WORKSHOP % THANříPORT UNCI IN KICKING

can bo higher and can vary between I80-210"C, If the temperature is higher tlum 2!J0"O some continuous degradation of TR HOI M appears, However this degradation is not instantaneous but only after some time (in our rase it was after 0-6-1.0 hour), There is a very important degradation if the temperature roaches 250"C.

The proposed modification of the MnknlUiti mmh only « continuous survey of the temperature of honiogcnisation, it» duration and л check of the degree of modification using я mícroHcopc This checking method is fast, unpretentious and sufficient ly reliable.

The results of this research work were verified in practice through fabrication of the modified asphalt for insulation purposes, Asphalt ЛР 80 and TR 1101 M in granulated form were used for the fabrication. Л short-term increase in the temperature of lioiiiogeiiisation led to a substantial reduction in thcliomogenisation time and loan improvement in the basic properties of the final product. The following properties were obtained during validation testing.

• Softening point ring-ball is 113°C • Penetration at 25"C in centimeters is U0.4 • Ductility at 25"C in centimeters is 31 • Breaking point is ЗГС • Flexion around former is less than -20"C

The practical verification confirmed that it was possible to decrease the time needed for optimal modification by thermoplastic rubber Til 1101 and increase its efficiency.

The possibility of modifying road binders by adding MODAS (produced from wasted rubber) was investigated in a similar manner. It lias been demonstrated that, also in this case, a suitable optimisation of the modification leads to an improvement in the properties of the modified binder.

Following the proposals of the CTU grant for "Improvement of the Reliability and Security of Roads" we focused on the observation of the rhcological properties of modified asphalt mixes. Recent experience has show that the standard testing methods are not able to judge the quality of modified mixes, Tims new testing methods have been established since last year — examining the modulus of rigidity, both the dynamic and static creep and fatigue properties.

The first measurement of modified mixes have been carried out this year and the results have been compared with results from abroad. It has been shown that our mixes have properties in both the low and high temperature ranges which are fully comparable with foreign mixes. Nottingham Asphalt Tester, obtained within tiie framework of the Tempus programme was used for the measurements.

This research has been conducted at the Department of Highway Engineering as part of the research project "New Possibilities for Modification of Asphalt Binders and Mixes" and has been supported by the Faculty of Civil Engineering CTU grant No. 2053.

882

WORKSHOP flfi TRANSPORT ENGINEERING

PHOTOGRAMMETRIC SURVEYING OF CONSTRUCTION OBJECTS'

DEFORMATIONS P. Dvořáček

OTU, Fac. of Civil Eng., Dcpt. of Mapping & Cartography Tlwkurova 7, 1G6 29 Praha С

Key words: photogranimclry, deformation

In technical practice, we often face a requirement to specify the spacial position of points of a deformed constructional or machinery object. Various geodetic and engineering measuring methods arc used. Under difficult circumstances, utilization of photogrammetric methods may he sometimes more suitable, i.e. the methods of non-contact measurement of the imago coordinates on measuring images. These methods enable one to eliminate some unfavourable circumstances which influence utilization of geodetic or engineering methods. In addition to this, photogrammetry provides the possibility of documentation of the object's current status on measuring images, the measuring on preserved images; may be repeated or completed at any time.

For specification of deformation movements, so called method of time basis is often used. The points subject to deformation changes arc photographed in certain time periods. The accuracy of the movement specification is in this case influenced oidy by the scale of images (which depends particularly on the distance of the photo station from the monitored points) and on the accuracy of the image coordinates specification. The disadvantage of this way, however, is the possibility of specifying the movements only in the plane parallel with the plane of the measuring image.

The spacial position of a point can be photogrammetricly specified only through the measuring of the image coordinates on the images taken at various stations. Simultaneously, eacli specified point must be reflected at least on two images. In practices so far, the stcrophotogramnictric method has been applied most often (the stereo pair has the parallel axes of scene). For more accurate work, this way is quite insufficient since the basis ratio (the ratio between the distance to the photostation and the distance between individual photostalions) is unfavourable. Much better results derive from analytic methods of photogrammetry where for specification of spacial position of points, images are taken with mutually convergent axes of scene. The basis ratio then ranges up to a value of about 1, the angle of the reflection rays' intersection is then much more advantageous.

The possibilities of convergent images have been so far limited with unaccesable or poor provision of computation technology and software provision. The Department of Mapping and Cartography has succeeded to gain, within the project performed under the patronage of the Central European Inicative (CEU), the program system ORIENT. This system comes from the Institute of Photogrammetry and Remote Sensing TU Wieti. This is an universal program system namely intended to do rigorous adjustments in the field of photogrammetric point determination. It enables one to process simultaneously many measurements and parameters.

883


The following can be measured: image points, model points, polar points (direction, zenith angle, distances), fictcous observations (under the condition that the points are on a curve or plane mathematically determined).

Parameters are components of image orientation in the space, and additional parameters which specify the geometric deformation of the image or describe the shape of the object in ficteous measuring.

ORIENT is suitable for various applications of analytic photogrammetry starting with close range photogrammetry through analytical acrotriangulation. It enables one to process images taken with non-metric cameras, the result may be also the calibration of such a camera.

The system installed on a PC is tested and ready for utilization in the area close-range photogrammetry. The system's functionality testing is done on a test object (the training centre FCE in Srbsko near Beroun).

The object was photographed with a universal metric camera UMK 10/1318 (Zeiss Jena), and with a non-metric camera (Kiev). On the object, 30 control points were measured at the first stage, then control points for verification of the measuring accuracy.

For the measuring of image coordinates, an accurate stereocomparator STECOMETER was used. The measuring was monocular, the accuracy of image coordinates specification has a range of about 0.005 mm. After preparation of input values, which must be given proper care and relative time, the procedure continues with the calculation with adjustment. After adjustment, the analysis of errors can be done. In the mentioned case, adjustment was performed several times, always with different numbers and different configurations of the control points. A satisfactory solution depends, in addition to proper specification of image coordinates, particularly on the suitable location of control points and the suitable direction of individual images. The residts of spacial position of points specification met our expectations. Although the points were not signalized, and their identification in the image was not ideal, the accuracy of point position could be determined with the variance of 0.01m.

On the basis of the successful system functionality testing, the processing of tasks is being prepared in the area of spacial movement of points monitoring. These arc particularly measurements of deformation changes in the tunnel under Letná in Prague. This is a suitable area for photogrammetry application, due to the limited and short-term possible access to the object (traffic totally stops only when the walls are being cleaned). A testing measurement has been performed with a metric camera, and a suitable method of a minimum number of control points specification is being prepared.

References:

[1] WALDHAEUSL, P. - KAGER, H.: ORIENT - a universal photogmmmetric adjustment system. Product Information. Institute of Photogrammetry and Remote Sensing, TU Vienna 1990.

[2] Proceedings. ORIENT Seminar. Institute for Photogrammetry and Remote Sensing TU Vienna & Dpt. of Surveying FCE STU Bratislava, 1994

This research has been conducted at the Department of Mapping & Cartography and has been supported by CTU grant No. 2088.

884


MEASUREMENTS OF THE STRUCTURES OF THE CARRIAGEWAY

J . Sýkora

CTU, Fac. of Civil Eng., Central Laboratories Thákurova 7, 166 29 Praha 6

Key words: pressure boxes, strain gauges, embankment, bitumen, natural ground, loading vehicle, tension

This article deals with the preparation of transducers for measuring in the embankment and the construction of the carriageway during static and live load by vehicles. It describes the way of taking measurements and evaluating the results of the measured values gained on the carriageway at test track of the Skoda Volkswagen Group motor works in Úhelnice near Mladá Boleslav. The place for the measuring of the response was chose where the body of the embankment is 2,85 m high, on its formation level of frost blanket course is 20 cm, two more layers arc of rolled concrete (15+10cm) and the carriageway is closed by multilayer bituminous surface. To state the tension in the natural ground, in the embankment and in the frost blanket course the so called pressure boxes were used. These boxes removing the possible vaulting effect in the environment in which they have been embedded, have been developed by the author. The stiffness of the boxes is a little lower than that of the enviromnent.That doesn't cause any difficulty in regard to their construction.

Commercial strain gauges DA 3 of the firm Hottinger Baldwin Mcsstechnik were embedded in the rolled concrete and the last bituminous layer. It was also necessary to build in these transducers when the construction was already under way, which was difficult to organize. Since the last bituminous layer was of very poor quality, it had to be milled off together with the strain gauges and new ones had to be embedded in the new layer.

In picture 1, is shown the cross-section of the construction of the carriageway and the embankment together with the embedded built-in transducers.

T 239.94

' j — Uk 3 bitumen Zz DA 3 concrete

^ 2Э7.09

20 —

21 —

13

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2 6 — 3 0 •» , 4 «

9 —

9 —

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• * •

• * •

•*•

• * •

• * •

• * •

239.79 239.39

239.73 embankment

239.16

237.99

239.91

i L U U p r e . e u r e " ^ ^ • I r . l n y . u g .

Fig. 1: Cross-section of the construction Fig. 2: The response of a moving vehicle

885

WORKSHOP OS TRANSPORT ENGINEERING

The loading vehicle was a fully loaded thrce-axlc Tatra 815. The place where the transducers had been put was loaded directly by the left wheels of the axles. During the static loading the response to three positions of each wheel wns recorded. Values at various speeds from 5 km/h to 90 km/li were recorded during drives.

В ПГ 24 W

"4. pressure ^ ^ » " y V вивЫ umuQc

32o

Fig. 3: The response of a braking vehicle Fig. <1: The response of a moving vehicle

As proved in the graphs (Fig. I and 3), the strain gauges in the bituminous layer show a sudden change of polarity at the moment when the wheel moves over the transducers, At the time of this measuring 10.00 to 14.00 hours the sun was shining, the temperature reached 25°C and the temperature of the bitumen layer must have been much higher.

Similar measurements were taken later and the courses of the strain gauges are completely different as seen in Fig. 4. The change in polarity is missing, That may have boon caused by the weather: the day was cloudy, with temperature not over 20°C.

Since the measured value of tension in the embankment is very low it is clear that the quality of the surface of the carriageway undoubtedly depends on the construction of individual layers. Cracks in rolled concrete (as well as functional unsupported joints in carriageway with concrete pavement) affects greatly the growth of tension in the underlying layers. This results in further destruction of carriageway or at least its evenness deteriorates. The measuring also proves that smooth driving loads the carriageway less than hard braking and stopping or a static load. From the point view of loading by traffic it isn't necessary to take so much care over the construction of the ground and the embankment of the carriageway. I think that the relatively expensive construction of experimental sections would have a multiple and longtcrm financial effect. The consumption of material for the construction could be cut down and the durability of the carriageway would be prolonged.

References: [1] SÝKORA, ,1.: The Response of the Construction of the Carriageway, p. 137-142,

Vol. I., 3rd Int. Conf. Traffic Effects on Structures and Environment — TESE 94, The High Tatras, Slovakia 1994

[2] SÝKORA, .1.: Vyhodnocení měření napěli it živičných vrbinách a zeminách. (Evaluation of stress measuring in the bituminous layers and in soil.) p. 345-349, 27. konference EAN, CSVTS Nitra 1989

This research lias been conducted at the Central Laboratories as part of the research project "Zdokonalování metod měření a vyhodnocování na stavebních konstrukcích" and has been supported by CTU Vac. fo Civil Eng. grant No. I7/,II.

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Section 20

DEVELOPMENT

OF STUDY

WORKSHOP 95 DEVELOPMENT OF STUDY

ECOTECHNOLOGY — A NEW STUDY BRANCH AT THE FACULTY OF

MECHANICAL ENGINEERING, CTU

F. Drkal

CTU, Fac. of Mechanical Eng., Dept. of Environmental Engineering Technická 4, 166 ОТ Praha 6

Key words: ccotcchnology, environmental protection, education, mechanical engineering

The machinery used in production, chemical and power industries, agriculture and technical services is one of the main sources of environmental pollution. The steps taken towards improving the status quo are focused on changes in technology and design in order to reduce the production of polluting substances and waste energy.

Besides, there is a growing need for design of specific equipment intended for separation, cleaning, recycling, recuperation, absorption and reduction of mass and energy waste. This includes machinery for air and water protection, solid waste treatment, noise and vibration control, air conditioning. Different kinds of such equipment are all based on common principles; mostly on momentum, heat and mass transfer applications, thermal and hydraulic processes.

The solution of machinery design and production technologies from the view-point of their impact on the environment has been already an integral part of study courses at mechanical engineering faculties. However, the problem of specific equipment reducing the production of polluting substances and waste energy has not been considered within the current curricula.

The decision made during our work on the development project was to arrange a separate interdisciplinary study course which is named "Ecotechnology". The syllabus for the fourth and fifth years of study was included in the curricula of the Faculty of Mechanical Engineering, CTU in Prague [1] and is a part of the report [2]. The main collaborators on the Faculty project are: Dept. of Environmental Engineering, Dept. of Chemical and Food Process Equipment Design, and Dept. of Thermal and Nuclear Power Plants. There are other departments taking part in the project: Dept. of Compressors, Refrigeration and Hydraulic Machines and Dept. of Transport, Construction and Agricultural Machinery.

A part of the project was to introduce the building energy computer modelling and simulation in the curricula of the Dept. of Environmental Engineering. The Faculty of Mechanical Engineering obtained the ESP-r software for the research and teaching purpose on the basis of licence agreement with the University of Glasgow, Dept. of Mechanical Engineering.

From the necessity to protect and conserve our environment arises the need to reduce our society's impact on the nature, to conserve the limited stocks of fossil fuels and/or to make the use of more efficient renewable energy sources. Since buildings arc one of the major consumers of energy and also have considerable overall impact, the built environment is one of the most important target areas for addressing the ahove issues.

One of the most promising ways to achieve protection and conservation of the environment, is by ensuring - through education and training - that (future) engineers working in

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related fields will have the knowledge and the skills to use the state-of-the-art technology and to bring it into practice.

In the collaboration between the Dcpt. of Environmental Engineering and the Energy Systems Division, University of Strathclyde, the ESP-r (Environmental System Performance) software has been installed recently by Dr. Henscn on UNIX workstation in the Information Technology Centre at the Faculty of Mechanical Engineering. The computer simulation using ESP-r gives us the answer to the following fundamental problems:

What and when are the peak building loads and what are the rank-ordered casual energy flows?

What are the effects of some design changes? What is the optimum plant starting time or the most effective algorithm for weather

anticipation? What are the energy consequences of non-compliance with prescriptive energy regula

tions, or conversely, how should a design be modified to come within some deemed-to-satisfy performance target?

What heat recovery system performs best under a range of typical operating conditions? Two one-week workshops for departmental stafT and postgraduate students of Environ

mental Engineering took place in Prague under the supervision of Dr. Flensen. Within the student scientific competition the study [3] by T. Dunovska got the first prize.

The collaboration between the two institutions initiated a proposal for the TEMPUS project named "Introduction Building Energy Modelling and Simulation into Higher Education of Environmental Engineering Using Information Technology". The project assumes these partners: Slovak Technical University in Bratislava, Technical University of Budapest, Technical University in Sofia, Technical University of Wroclaw, Eindhoven University of Technology, University of Strathclyde in Glasgow (co-ordinator), Faculty of Mechanical Engineering CTU in Prague (contractor).

The main objective of the project is curriculum development and overhaul or modernisation in the priority areas. Although the project will be carried out at leading Universities, a mechanism will be incorporated to ensure that deliverable materials will be "automatically" dispersed to other universities within and outside the countries involved as well as to practitioners in the industry. Within the proposed project the target courses will be in the final-year and at the postgraduate level. Each participating country will have its own industrial partner involved in developing the courseware and - in later stage - in transfer to the industry.

References: [1] Curriculum 1994/1995 (in Czech). Faculty of Mechanical Engineering CTU in Prague. [2] DRKAL, F.: Ecotechnology - a New Study Branch at the Faculty of Mechanical Engi

neering CTU in Prague (in Czech). Faculty of Mech. Eng. CTU in Prague. 1994. [3] DUNOVSKA, Т.: Industrial Hall Energy Balance Analysis for Summer Period via

Computer Simulation (in Czech). Faculty of Mech. Eng. CTU in Prague. 1994.

This research has been conducted at the Department of Environmental Engineering as a part of the research project "Ecotechnology - a New Study Branch at Faculty of Mech. Eng. CTU in Prague" and has been supported by CTU grant No. 1121005.

890


DEVELOPMENT PROJECTS IN COMPUTER SUPPORTED EDUCATION

OF PHYSICAL ENGINEERING L. Drška, R. Liška, M. Šiňor, J. Vondrášek

CTU, Fac. of Nucl. Sci. & Phys. Eng., Dept. of Physical Electronics V Holešovičkách 2, 180 00 Praha S

Key words: computer aided instruction, introductory physics courses, computational physics, computer algebra, integrated computing systems

This contribution describes some developments and results related to the systematic use of computers in the education process at the Faculty of Nuclear Sciences and Physical Engineering of the Czech Technical University in Prague.

Typical software tools under DOS operating system which have been used in the work described in this paper include authoring system GENIE, hypermedial system ENCYCLOPEDIA, simulation and visualization program FAMULUS etc. For the work clone under UNIX the development package delivered by SGI for the IRIX system and many other programs have been available.

To prepare conditions for systematic application of computer algebra (CA) and integrated computing systems (ICS) in high-tech research and education a dedicated R&D facility (ICSF) has been established. It includes two low-end workstations SGI Indy R4000 SO and two personal computers S04S6 with the possibility to also use the vector minisupercom-puter CRAY Y-MP EL (Institute of Physics, Academy of Sciences) and the multiprocessor SGI POWERChallcnge system (CASP). The ICS available at this facility are listed in Tab. 1 ($ = planned future extensions).

Tab. 1: Integrated Personal computer

Derive Maple

Mathematica Reduce

computing systems used / to be used in ICSF Workstation

Maple Mathematica

Reduce MuPad

Axiom $

Supercomputer

Maple Mathematica $

Two courses for introductory physics based on the complex application of computer technology with stressed role of the programs Famulus and Derive have been proposed.

The first course "Introductory Physics Using the Computer" is considered as a supplementary course to the standard lectures in elementary physics. The course, delivered in the second semester, has an unconventional structure, as shown in Tab. 2.

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Tab. 2: Introductory physics using the computer Computer-based approach to physics A bit of numerics for pedestrians Classical physics milestones Traditional and new topics in physics

Mechanics and thermodynamics Electrodynamics and light Nonlinear physics

Student's miniproject

Applied every-day physics

The second course "Concepts of Modern Physics Via Computer", scheduled for the fourth semester, includes mainly topics from elementary quantum mechanics and physical kinetics, some applications of the modern physics are also presented.

As a response to the new developments in the field of computer technology a revised version of the course "Methods of Computational Physics" has been developed. The course, taught in the eighth semester, consists of the following: Computers in physics. Small computer technology. Traditional computational physics. Integrated computing systems. Technology of intensive computing. Prospects of information physics. Students' projects.

To support a progressive approach to the mastering and potent use of CA/ICS [1] a hy-permedial presentation/educational program "Computer Algebra and Integrated Computing Systems" has been developed. The software lias been realized in the system ENCYCLOPEDIA in Czech and English variations. It is targeted for personal computers and workstations. The contents of the package is listed in Tab. 3 ($ = planned future extensions).

Tab. 3: Hypermedial course on integrated computing systems Introduction Algorithms for algebraic computations Computer visualization fundamentals $ Survey of integrated computing systems Basic capabilities of 1CS Applications of ICS in science and engineering ICS in university education $ Case studies of ICS applications Study sources for ICS Commercial informations about ICS Conclusion

References:

[1] DRSKA, L. - LISKA, R. - SINOR, M. - VONDRASEK, J.: Integrated Computing Systems in Physics Education. Presented at the 1994 European Mathematica Conference for Advanced Users, Oxford, September 18 - 20, 1994 (hypermedia document).

This research has been conducted at the Department of Physical Electronics as part of the research project "Facility for the Application of Integrated Computing Systems" and has been partially supported by grant No. V307 of the Czech Ministry of Education.

892


FIRST COURSE ON TRUSTED TELEINFORMATIC SYSTEMS

AT FEE CTU IN PRAGUE J. Přibyl

CTU, Fac. of Electrical Eng., Dept. of Telecommunications Technická 2, 166 27 Praha 6

Key words: trusted teleinformatic systems

In this contribution a course description of the designing of trusted teleinformatic systems at the Faculty of Electrical Engineering - Czech Technical University in Prague is described. Not only abstracts of lectures but also the examples of individual students' projects and research activity at the Telecommunication Department on privacy, security and accuracy are presented.

Since the "Velvet Revolution" in 1989 the telcinformatic systems in the Czech Republic have been emerging at a furious rate. Unfortunately, this process has been accompanied by criminal activities, malicious damages, invasion of privacy, and other security exposures. Because of the growing criminal activities and other negative factors, top management of my faculty accepted my recommendation to organize a course on designing trusted teleinformatic systems. This course was included in the structure of the new education program of our faculty in 1993 and realized for the first time in the spring of 1994. The lectures were divided into four sections according to the four layers of security, privacy and accuracy controls used in trusted systems. The effectiveness of these lectures was enhanced by individual students' projects, the themes of which were oriented towards the designing of different types of cryptographic systems for use on microcomputers. In June, I proposed to the Ministry of Education, Youth and Sports a project to be funded by a research grant for the 1995 year of developing a modified public key cryptographic system which could be applicable in computer networks of the Ministry and of Universities of our republic. The proposal is now being studied.

The lectures are divided into fourteen blocks, each with following structure:

1. Layers of protection. Security exposure. Possible errors in teleinformatics system. Commercial secrets and individual privacy.

2. Design procedure of the trusted teleinformatic system. Accuracy controls on batch processing and on real-time systems.

3. Accuracy controls in teleprocessing. Criteria for choice of code. Error-correcting codes. M-out-of N codes. Polynomial codes. Error-detection probabilities. Error sequences, measurement and efficient storage.

4. Devising the steps for overbridging the situations, when failures occur. Programmed locks. Alarms. Identifying the terminal users, computers and data terminal equipment.

5. Authorization schemes, tables and their use. Alarms and surveillance procedures. Security levels and access categories.

893


6. Cryptography. Valuation of secrecy systems. Fundamentals of the theory of secrecy systems. Basic examples of secrecy systems. Programs for enciphering data. Stcganog-raphy.

7. Recovery techniques. Journaling and file balancing. 8. Locks, vaults, and protected areas. Electronic security devices and systems. Fire

-detection and control. 9. Protection against sabotage, communication-line wiretapping and electromagnetic ra

diation and system eavesdropping. 10. Responsibility for security. Classification of data. Vital-records program and system

recovery. Controls of the programmers. Psychology of potential system breakers and psychological security. Auditing.

11. Legal and societal controls. 12. Trusted computer system evaluation criteria from Orange Book point of view. 13. Information processing standards in Western Europe. 14. Case studies.

During the first spring course on trusted teleinformatics systems demo computer programs specified by the following list were realized:

1. Simple Substitution Cipher 2. Transposition with Fixed Period 3. Vigenere Cipher with its Variations 4. N-gram substitution Cipher 5. Matrix System Cipher 6. Playfair Cipher 7. Autokey Cipher 8. Fractional Cipher 9. Multiple Mixed Alphabet Substitution

At this time my students are solving several diploma projects with the following titles:

1. Public key cryptographic system for use on microcomputers 2. Trap-door one way functions in application for public key cryptography 3. Algorithms for finding large pritnenumbcrs 4. Is the RSA system unbreakable?

The results will be implemented in a modified public key cryptosystem for use in computer networks of our universities.

Other related activities are:

1. Cooperation with the AFOI - Association of Firms for Information Protection 2. Cooperation with the Computer Department of the Institute of Criminology 3. Preparation of the 4th International Conference DROMS'96 - Design, Realization, Op

eration, Management and Strategy of Trusted Distributed Data Processing.

This research has been conducted at the Department of Telecommunications as part of the research project "Modified Public Key Cryptographic System" and it will be supported by CTU grant next year.

894

WORKSHOP !),rj DEVELOPMENT OF STUDY

COURSE OF NOISE CONTROL

R. Novy

OTU, Fac. of Mechanical Eng., Dept. of Environmental Engineering Technická •!, 1GG 07 Praha G

Key words; education, acoustics, noise

Within the last few years, concern about the protection of the environment has grown rapidly as it has become generally recognised that the steady rise in pollution of all kinds cannot be allowed to continue indefinitely. The acoustic environment lias likewise sneered from the increase in use and power of machines in the workplace, increasing road traffic, large aircraft, etc. To combat this, many countries and communities have recently introduced legislation making it a legal requirement to measure community noise level, to reduce noise from vehicles at source and to maintain acceptable noise levels in factories lo prevent hearing loss. This activity has led to greater appreciation of the benefits of a quiet environment and a preference for quieter domestic products, if these are available. The quieter item therefore often has a sales advantage over its more noisy competitor which may be reflected in the command of a higher price. Economic advantages are also apparent in property values which are lower in noisy areas than in quiet areas.

These problems must be worked out in a few steps. One of them is the necessity to train many specialists ii) acoustics branches, mainly in noise control. The following recommended course was compiled to provide large information about the physical foundations of technical acoustics, acoustic measurements of noise, measurements of vibration, psychological acoustics and psyrhoacotistics criteria, and mainly the methods of leducing noise.

The course is proposed on the basis of experiences with two coin ses on the same topic, which were organised at the Faculty of Mechanical Engineering during the 70ics. The course consists of subjects of following contents:

1. ACOUSTIC WAVE PROPAGATION IN EXTENDED FLUID MEDIA WITH NEGLIGIBLE DISSIPATION - wave motion in fluid media - characteristic wave equations -acoustic potential and general wave equations - analysis of time change and space distribution - energy of the acoustic wave - gravity waves - numerical determination of the characteristic quantities of the field - sound spectra - sound waves incident on a flat surface of discontinuity - ray theory - propagation of sound in real medium - temperature gradients, humidity and precipitation, the effects of wind, absorption by natural features - diffraction.

2. PSYCIIOACOUSTICS AND NOISE CRITERIA - the hearing mechanism - masking and the critical bands - loudness and its determination - loudness of short duration sounds - steady noise - impulsive noise - noisiness, subjective rating - overall sound pressure level -community noise annoyance, criteria and rating procedures.

3. SOUND PROPAGATION IN CHAMBERS - three-dimensional sound equation -sound fields in small regularly shaped enclosures - resonance frequency - sound fields in large irregularly shaped enclosures - energy density - sound absorption coefficients - air and boundary absorption - determining of the sound pressure level in large irregular room -reverberation time - sound fields in rooms - sound absorbers - room faults - examples of room acoustics calculations.

S95

WORKSHOP »3 DEVELOPMENT OF STUDY

•1. ACOUSTIC WAVE PROPAGATION IN LOSSLESS SOLIDS - strains of the medium and the strain tensor - stresses in the medium and I lie stress tensor • general stress-strain relations - equations of motion in solids - energy of acoustic waves - Rayloigh waves.

5. SURFACE SOURCES OF ACOUSTIC WAVES - general method of determining the source radiation - simplified general formulas for the source radiation - the field characteristic of the source - characteristic of the source as a vibrating system - radiation of spherical sources -the field characteristic of a circular membrane - the radiation of other types of piston membranes - the radiation of a group of sources - the source perturbation in a solid medium - radiation transients of sources.

6. SOUND GENERATION BY FLOW - p^dietion of flow generated noi.se - LigUbill's acoustic analogy - noise of jet - aerodynamic sources in practise - fan noise - flow generated duct borne noise.

7. SOUND TRANSMISSION TROUGH WALLS - transmission loss - reduction оГ airborne sound - sound reduction index - sound insulation of a single leaf partition - sound insulation of double leaf partitions- sound transmission through non-homogeneous partitions - sound insulation requirements - noise break-in through building facades - covering of machines,

8. VIBRATION ISOLATION - fundamental theory - damping - viscous damping -friction damping - mounting arrangements - modes - motion - vibration isolators- selection - weight distribution - towards the final selection - inertia bases - Hanking - structure and ground borne vibrations - floating floors.

9. ACOUSTIC NOISE MEASUREMENTS - general considerations - basic measuring system - portable measuring instruments - laboratory measurement and analysis system -measurements procedures - noise control in workshops - noise analysis.

The course is planned for approximately 'lh applicantse, who are expected to pay a school fee of 15 000 KR, which is calculated for two terms.

References: [1] NOVY, R.: Noise Reduction. CTU, Prague 1<JSG. [2] DEDOUCH, K. - NOVY, R. - RANSDORF, .J.: Noise and Vibration of Machines.

CTU, Prague 1990. [3] BERANEK, L. L.: Acoustics. American Institute of Physics, Cambgidge 19S6.

This research has been conducted at the Department of Environmental Engineering as part of the research project "Noise Control'' and has been supported by EliVS grant No. 112Í 008.

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http://noi.se

WOHKSIIOP 05 DEVELOPMENT OF STUDY

PROJECT OF A CONTINUING EDUCATION COURSE ON

"AIR POLLUTION CONTROL"

J. Hemerkn

CTU, Fac. of Mecbanical ling., Dopt. of Environmental engineering Technická 4, 166 07 Praha 6

Key words: continuing education, environment, air pollution control

The last course of the Continuing Education Course on "Air Pollution Control", organized by the Department of Environmental Engineering of the Faculty of Mechanical Engineering CTU, took place in 1980. Many changes have occurcd in this field since then. The most important changes are in legislation - new Clean Air Act and subsequent acts that establish obligatory emission limits for individual sources of emissions, international Convention on bong-distant Transfer of Pollutants and several Protocols to this Convention bring international engagements in reduction of most important pollutants. For the reduction of gaseous emissions new separation techniques have been developed, new tendencies have appeared in the particle separation by means of industrial filters, electrostatic precipitators, wet separators combined with collecting gaseous emissions and so on. An important progress has been made in measuring techniques of both gaseous and particle emissions. All these facts support a social demand for reestablishing the course for continuing education of specialists in the field of air pollution control.

As the result of consultations with experts — external lecturers — a new curriculum of the course and syllabuses of individual subjects have been prepared.

List of individual subjects, lecturers and extent of subjects in

1. 2,

3.

'1. 5. 6. 7.

S.

9. 10.

Legislation in Air Pollution Control Sources of Solid Emissions

Sources of Gaseous Emissions

Transfer of Pollutants in Atmosphere Separation of Solid Emissions Separation of Gaseous Emissions Measuring of Solid Emissions Laboratory Measurement Measuring of Gaseous Emissions Automatic Analyzers Manual Methods Effects of Pollutants Measuring of Imissions Total

Ing. Kuzel 15 Ing. Hcjma 5 Ing. Kurfurst 5 Ing. Brclschneider 10 Doc. Holoubek 5 Dr. Bubnik 10 Doc. Hemcrka 15 Ing. Petioky 15 Ing. Burcs С

'1

Doc. Bartovsky 10 Dr. Bubnik 5 Prof Havránek 10 Ing. Santroch 10

125

Lectures will be organized in four week courses, each consisting of 30-35 hours.

897

WORKSHOP 95 DEVELOPMENT 01" STUDY

Total costs were calculated for a group of 15 participants and consist of organization costs, lease of lecture room, preparation of teaching texts, payments of lecturers, travelling expenses of lecturers, costs for exams, diploma works and their defence, Total costs are estimated at about 250 000 CKR and an enrolment fee for I participant would be about 16 700 CKIl.

Short syllabuses of individual subjects

1. Legislation in Air Pollution Control Principles and interpretation of acts in air pollution control; register of sources of emis

sions; international convention on long-distant transfer of pollutants and conventions on sulphur dioxide, nitrogen oxides and volatile organic compounds.

2. Sources of Solid Emissions Heat production and power plants; production and processing of building materials and

other mineral products; production and processing of metal materials; waste processing. 3. Sources of Gaseous Emissions Sources of emissions of sulphur dioxide, nitrogen oxides, carbon oxides, hydrogen sul

phide and carbon disulphide, chlorine and chlorine compounds, fluorine and fluorine compounds; production of main acids; sources of hydrocarbon and other volatile organic compounds; sources of persistent organic pollutants.

4. Transfer of Pollutants in Atmosphere Thermodynamics and aerodynamics of atmosphere; wind and temperature structure;

diffusion of pollutants in the atmosphere; influence of topography; principles of dispersion studies.

5. Separation of Solid Emissions Physical and transfer properties of solid particles; principles of .separation; general

properties of separators; dry and wet mechanical separators; industrial niters; electrostatic separators.

6. Separation of Gaseous Emissions Physical and chemical properties of matter; principles of separation of mixtures into

fractions; principles of sorption processes, chemisorption, condensation methods, biofiltcrs, catalytic oxidation and catalytic reduction.

7. Measuring of Solid Emissions Classification of measuring methods; basic terms and definitions; gravimetric method;

photometric method and instruments; radiometric method and instruments; taking of samples.

S. Measuring of Gaseous Emissions Classification of measuring methods; general properties of analyzers; basic principles

used in automatic analyzers; data processing; manual measuring methods. 9. Effects of Pollutants Influence of pollutants on people, utility animals, vegetation, forestry, corrosion of

materials, buildings. 10. Measuring of Imission Manual methods used for most important pollutants; basic principles used in automatic

analyzers; automatic imission monitoring; smog warn and regulation system. This research has been conducted at the Department of Environmental Engineering as

part of the, research project "Project of a Continuing Education Course on Air Pollution Control" and has been supported by FRVS grant No. 11 21006.

89S


PRACTICAL FORMS OF EMC EDUCATION

J. Svačina, J. Soldáti*

TU Brno, Рсчс. of Electr. Eng. and Сотр. Science. Dept. of Radioclcctronics Antonínská 1, (i(i2 0!) Urno

^Military Technical Institute of Ground Forces 010, (582 03 Vyškov

Key words: EMC education, EMC testing, EMC laboratory experiments

This project is continuation to the 1993 educational research project entitled "Grad-ualc and Posl-Gvadnnlc Education in EMC" in which the educational problems set were examined at the Department of Radioelectronics TU Brno, financial assistance being given by the Ministry of Education in Prague [1]. The aim set for 1994 was the development and realisation of the graduate curriculum in EMC for electronic engineering specialisation of the study mainly in its practical forms. The curriculum was taken as part of the existing programme in the specialisation "Electronics and Communication" at the Faculty by including the property EMC topics in suitable "standard" courses. In this specialisation many courses are able to incorporate the EMC topics in their programmes [2].

All lectures these courses arc accompanied by property laboratory experiments and/or computer simulations which can be made easily more oriented to the EMC concepts. A review of the EMC oriented experiments and simulations is given in [Ij and [3]. Some of these are combinations of lab/demonstrations, i.e. the teaching assistant demonstrates the concept in the laboratory and the students then do some "hands-on" work.

In addition, a dedicated EMC course entitled "Electromagnetic Compatibility" will be introduced at the Department of Radioelectronics during the 1995 summer term. The course will be given for students in the last year of their graduate study and it is intended to be a broad and comprehensive review of the main technical aspects of EMC. The list of main topics in the course is following:

1. Introduction to EMC (history, basic concepts and problems, examples) 2. EMI signal sources (natural and wan-made EM environment, disturbing signals) 3. Coupling mechanisms of EMI signals (arls of couplings, radiated emission) 4. Filtering, isolation and sttpprcsion 5. Grounding and shielding (shielding effectiveness, effect о J apertures) 6. EMC measurements and instrumentation (EMI and EMS measurements) 1. EMC standards and regulations (international, national and military standards) 8. Selected EMC practical problems (EDS, protected military systems, data protection)

The lecture courses arc complemented by a scries of three laboratory and computer experiments each taking one day to be complete. These experiments have the form of practical industrial training which will be held in the EMC test laboratories of the Military Technical

899


Institute of Ground Forces 010 in Vyškov near Brno. In this Institute the EMC measurements are routinely performed with the help of professional EMC measuring systems. The student's experiments are planned to be following:

a) EMI measurements (measurements in a screening room): - Measurement of conducted emissions:

- The line impedance stabilization network (LISN) - The voltage and current probes - Measurement witli the absorbing clamp

- Measurement of radiated emissions: - Electric field measurement - Magnetic field measurement - Electromagnetic field measurement with various types of antennas

b) EMS measurements; - Generation of electromagnetic fields for EMC testing, testing cells and rooms - Susceptibility to harmonic fields and signals - Susceptibility to electrostatic discharge (EDS) - Susceptibility to lightning - simulation - Susceptibility to electromagnetic pulse (EMP) - Measurement of shielding effectiveness of various screened enclosures

c) Computer modelling and simulation in EMC: - Modelling the shielding and tabsorbing effect of materials - Modelling the parasitic coupling, transmission and crosstalk - Computer programs for EMC simulations and verifications of their results

AH these experiments and simulations will be realized on typical technical products, such as electrical home-equipments, personal computers, cars etc. The experiments and tests comply with the proper EMC requirements and regulations.

References: [1] SVAČINA, J.: Graduate and Post-Graduale Education in EMC (in Czech). Research

report of Grant project No. 1201, TU Brno, 1993 [2] Electronics and Communication (in Czech). Study programme at the Faculty of El.

Engineering and Сотр. Science, TU Brno, 199-1 [3] SVAClNA,J.: Education in EMC at Technical University Brno. In: Proceedings of the

International Wroclaw Symposium and Exhibition on Electromagnetic Compatibility EMC-94. Wroclaw 1994, pp.I10-112

This research project has been conducted at the Department of Radio electronics TU Brno and has been supported by TU grant No. С 21/94-

900


NEW MULTIMEDIA WORKPLACES J. Svoboda, В. Šimák, T. Zeman,

М. Vondrák, Р. Hypš, M. Hrad

CTU, Fac. of Electrical Eng., Dept. of Tclccommtinications Technická 2, 16G 27 Praha G

Key words: multimedia, electromagnetic compatibility (EMC), education

Telecommunications is a very important branch for industry as well as for public purposes. The education of Telecommunication engineers has recently developed along two lines — namely contributing to fundamental engineering technology and a multidisciplinary approach.

The Department of Telecommunication Engineering, Faculty of Electrical Engineering of Czech Technical University (CTU) in Prague has recently introduced a new programme structure that reflects various aspects of our changing world. We want to develop a comprehensive system of education using computers, signal processors, audio and video inputs/outputs and other available devices.

Our team is working not only on the development of new subjects but also on proposals about the teaching structure for a wide range of problem-solving. The working group at the Department of Telecommunications at CTU in Prague operates in the areas of data interfaces, simulations of videotex services, basic courses of packet communication, data circuit termination, document facsimile telegraphy services.

The progress of the electrotechnics and informatics requires the following of the principles of the Electromagnetic Compatibility. Electrical and electronic devices are said to be electromagnetically compatible when the electrical noise generated by each of them does not interfere with the normal performance of the others.

Our activities concerning EMC are concentrated into collecting study materials, the creation of new curricula, the preparation of the EMC technical handbooks, the construction of the EMC laboratory for teaching measuring and testing technology, consultations, publications, conferences. Mainly, wc have focused on software support for EMC education, and the construction and expansion of hardware and software for multimedia-based working places.

For the development of teleinformatics and EMC multimedia-based learning programs, we have created a multimedia workplace. This involves the establishment of a complex system with a powerful computer, audio and video convcrtors, CD-ROM unit, tape recorder, computer controlled video recorder, viewframc with a good and reliable overhead projector and good color TV network. We have gathered special multimedia components:

A) devices for the creation and preparation of applications B) devices for the presentation of multimedia educational programmes C) mobile devices (with lower quality performance)

Owing to limited funding, it is not possible to use all these facilities simultaneously, and some components are available in very limited quantities. This workplace with the aforementioned equipment allows us to create educational programmes of good, technically processed quality and in harmony with the latest trends.

901


In 1990, our working group was involved in ТЕМ PUS with a programme entitled "Computer Aided Learning and Simulation Technologies", hand in hand with the Hamburg Education Partnership. This cooperation opened new chances for our future relations. We have started to use the software product "Authorwaic Professional for Windows" which allows us to utilize the basic multimedia tools.

In recent years, for example, the following educational programmes were created:

A) Data Interface (19S9) - problems of interfaces 11 and 12. B) Videotex (1990) - simulation of Videotex Interactive Service. C) Facsimile Devices (1993) D) Principles of modern PABX (1993) E) Principles of Videotex (1993) - basic principles and main parametres of Czech Videotex

system. F) Date Modems (1993) G) Networks Architecture OSI (199-1) II) PAD - Packet Assembling and Disassembling (1994) I) Measuring of EMI (1994) J) Electromagnetic Susceptibility Testing (1994) K) Electrostatic Discharge (1994)

Our aim is to create applications stored on CD ROM discs. The programmes designed by the students and by the members of our group, will be used for teaching, and they will be at the disposal not only of students but also of other people who are interested in similar problems.

References: [1] SVOBODA, .1. - SIMÁK, В. - ZEMAN, Т. - VONDRÁK, M.: Expiricnce will, Com

puter Aided Education Programs Production in the Field of Tckinjormatics and EMC. Multimedia and Computer Tools: Fourth Annual Conference. CTU Prague, 8-10 September 1993

И SVOBODA, J. - SIMAK', B. - VONDRÁK, M. - ZEMAN, Т.: Education of EMC Experts. Proceedings of Workshop EMC 93. CTU Prague 1993.

[3] SVOBODA, J. - SIMÁK, B. - VONDRÁK, M. - ZEMAN, Т.: New Educational Ways for Engineers of Telecommunication. EAEEEIE Annual Conference Reims-France, June 1994

This research has been conducted at the Department of Telecommunications as part of the research project "Education of EMC Experts'' and has been supported lit/ Ministry of Education grant No. V 20/,.

902


A COMPLEX DIDACTIC SUPPORT OF GIS EDUCATION

AT THE CTU PRAGUE

M. Huml

CTU, Fac. of Civil Eng., Dcpt. of Mapping Sc Cnitography Thákurova 7, 166 29 Praha 6

Key words: education, geographic information system, computer network

Within the first working stage the main effort was focussed on the search for basic problem topics involved in education concerning geographic information systems (GIS) and land information systems (LIS).

In conformity with a quickly increasing interest to obtain up-to-date information about activity in territories and analytical-synthetical assesment, it is necessary to create well-educated professionals equipped with a corresponding theoretical background.

Л good understanding of the gcoinformntic principles, relations within GIS, and relations to other scientific disciplines has become a primary point of view in drawing up the basic tasks.

Using the up-to-date information sources (domestic and foreign) such as proceedings, books, articles, reports etc.is part of a normal working style.

The most recent knowledge emphasizes more and more the advantages of applying multimedia approach, using hypertexts and, in the case of data structure modelling, using an object orientation.

Л summmary of the basic thematic scopes and their contents is as follows: 1) DATA THEORY: feature, property, entity, attributes, domain, occurence, object,

spatial properties, data organization, data quality, metainformalion, classification. 2) GEOMETRY FOR SPATIAL DATA: different geometries, positioning of objects,

global reference systems, coordinates and splines, fractals. 3) TOPOLOGY: networks and graphs, graphs and areas, error identification, polygons

and areas, data for spatial relationships, considerations. 4) TESSELATION: mosaics, tesselation, lattices, geometry of regular tesselation, fixed

spatial resolution, regular cell grids, quadtrees, hierarchical lessclation, irregular tesselation. 5)MANIPULATI0NS: interpolation and extrapolation, basic operations on lines and

points, operations for polygons, spatial data transformation, transformation between regular cells and entities, access to spatial data, forms of spatial address.

6) SPATIAL ANALYSIS: integrating, operations for planar network entities, grid-cell based map overlay modelling, operations for quadtree tesselation, integration and multiple representation.

7) CONCEPTUAL MODELLING FOR SPATIAL DATA: methodologies, DBMS, enti-tyrelationships approach, relational database, transforming into relational models, CODA-SYL databases, table organization, information system design.

8) MODELLING OF LINE-ORIENTED OBJECTS, AREAS AND VOLUMES: seg-ments, polylines and mixtilincs, one-dimensional representation of polygons and areas, modelling for graphs and terrains, vector oriented geomatic models, spaghetti models, pizza models, octrees, pyramid models.

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WORKSHOP 95 DEVELOPMENT OP STUDY

9) SPATIAL DATA RETRIEVAL AND REASONING: algebras, spatial queries, access and quality, spatial indexing, topology.

10) HYPERMEDIA: multimedia spatial data, image data, organization of maps and images collection, hypcrmaps.

11) INTELLIGENT SPATIAL INFORMATION SYSTEMS: record-oriented database, towards to object orientation, classes, instances, inheritance, encapsulation, artiflicial intelligence and expert systems, spatial knowledge representation.

Thematic scopes will be divided into two educational terms and it is asMiined it will be a creation of didactical tests practised on a local computer network for the branch of geodesy and cartography at the Technical University in Prague. The question of how to spread education on GIS/LIS for the other branches is closely related to the quality of the computer network within the Technical University as a whole.

References: [1] AALDERS, II. .J.: Data Theory study materials, TU Delft, 1993. [2] ARONOFF, J.: Geographical Information Systems: A Management Perspective, WDL

Publications, Ottawa, 1989, ISDN 0-921S04-00-S. [3] ASPROTII, V.: 7Venrfe in GIS Research Areas, Proceedings EGIS'93, Genoa, 1993,

pp.17-25, ISBN 90-7341-1-11-3. [4] HARES, J. S. - SMART, J. D.: Object Orinlalion .John Wiley/Sons, Chichester, 1994,

ISBN 0-471-94124-7. [5] MOSS, P.: Informační technologie Vydavatelství ČVUT, Praha, 1993, ISBN 80-01-

O1048-1. [G] MCEWEN, L. J. - GREEN, D. R.: Undergraduate GIS: Quality Education and Training

with Limited Resources Proceedings EGIS'93, Genoa, 1993, pp.904-912. [7] LAURINI, R. - THOPSON, I).: Fundamentals of Spatial Imformalion Systems

Academia Press, Jovanovich Publishers, London, 1992, ISBN 0-12-43S380-7.

This research has been conducted at the Department of Mapping and Cartography as part of the research project "EDUCATION IN GEO IN FOR MATIC SYSTEMS AT THE CTU PRAGUE - A Complex didactic Support" and has been supported by CTU (TU) grant No. IS 160.

904

Section 21

ECONOMICS

&

BUSINESS ACTIVITIES

WORKSHOP Об ECONOMICS & BUSINESS ACTIVITIES

DEVELOPMENT OF CITIES AND REGIONS

V. Bcrnn

CTU, Рас. of Civil ling,, Dept, of Constr, Management fo economics Tlmkurova 7, 1GG 29 Praha G

Key words: transformations of cities, new technology, simulation, competitive strategy, fitncioual strategy

New angles of analysis arc required for transformations o[ cities and urban societies in Hast P/.irope. The question of development has changed. There are new priorities economic and social questions, East European cities concentrate on economic and social problems, but they are also sources of innovation and invention, The city is able to create the conditions for an effective economic environment and manipulate the financial potential of inhabitants and and people migrating to the city, There must be interaction between various levels of government and non-goverinneiital institutions or factors. The role of researchers like economists, urbanists, technicians, planifiers, sociologists working on urban issues is an important one, The main role is to help decision-makers choose their ways and means of actions, The now and global outlook on new urban chances and challenges is an important means to methodically support this struggle.

The reasoning of this process and rationalization of it must be supported by new technology, new ideas on how to create new values. The only productive, but not only suitable one is to manage transformation of new technology into production and services. That is an urgent need.

Contemporary design process puts forward in an ever increasing extent the problems of differentiation of "economic" and "uneconomic" features of the individual designs. It is coming to light in an ever increasing extent that in complex situations the classical economic instruments afford us less and less factual support for the selection of optimum design, and that the concept of "economy" must be understood in a complex and integral manner. Estimated costs, economic returns of investments the share of foreign financial funds, the share of deficient investment resources are all becoming more and more only a supporting criteria (or limits and constraints) in the assessment of the individual design variants rather than decisive factors enabling an explicit statement of what is and what is not a suitable solution.

This presented paper does not aspire to answering a theoretical question. However, it can draw the readers' attention to the fact from the practical point of view - aiming at the realisation of the design and clash with numerous working groups only indirectly connected with the design. In the case of designs of vast investment projects or structures intended for application on mass-scale construction, it is possible to overlook the fact that the work, when completed, will serve more favourably to some groups paiticipating in the creation of the national income, and less favourably to other groups, and that for some branches of the national economy this will even result in a worsening of the conditions creating the common values. Therefore, the responsibility of the designer and the contractor for the quality of the solution must be considered as the focal point of the problem. How to ensure adequate means for design assessment which will guarantee proportionate benefits and elimination of

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negative ofTccts of the design? The nietliods assessing the functional relations of the solution and permitting analyses of the causes of the "bottlenecks" in the design seem adequate for this purpose.

Every design passes through several phases of development, The phase of .generation of alternative solutions in the stage of investment intention or preparatory documentation may change the whole conceptual direction (scenario) of the possible solution of the problem at hand. From the phase of technical design, on the other hand, we expect the functionally correct selection characterized by the required overall permanent social effect over a long period of time.

The current phase of the technico-economic development is characterized through

a) the means of development of technical or economic projects based on an increase of material inputs, labour requirements, workability or machinery time requirements per unit production can be almost explicitly considered as exhausted,

b) the means of development based on the substitution of material resources through energy resources can be considered inaccessible in the future with great probability, The current state of the conditions for the implementation of tcclinico-economic projects is characterised by a change of qualitative criteria.

It's necessary to develop corporate strategy for tasks that cannot be delegated to lower levels in design and management, The rational strategic approach may be viewed from several points: i

• competitive strategy (strategy of business unit level), • functional strategy (finances, human resources, technology development, procurement,

manufacturing, marketing.

The main goal is to carry out comparative research on policies implemented by cities, on the innovative solutions proposed by them and on their foreseen and unforeseen effects. Public budgets are too limited to meet all the demands of urban populations, implementing such innovative policies. One of the comprehensible techniques is dynamic prognoses by means of simulation. The developed technique in the COST programm grant makes it possible to use this sophisticated technique to rather small computer equipment PC 386 or 486/ with 40 or more MHz.

References: [1] BERAN, V. - POLJAK, S. - KOLLERTOVÁ, J.: Computerized Management Systems.

ČVUT, Praha 1985.

This research has been conducted at the Department of Economics and Management in Construction Industry as part of the research project "COST" and has been supported by CTU grant No. 12655.

908

WORKSHOP ДЯ ECONOMICS fc BUSINESS ACTIVITIES

SOME CONSEQUENCES OF PRESENT HOUSING POLICY

IN THE CZECH REPUBLIC M. Plachký

CTU, Vac. of Civil Eng.. Dcpt. of Coustr. Managements Economics Thákurova 7, 166 29 Praha 6

Key words: housing, housing policy, rent, binding costs, housing costs

Housing belongs to one of the most complex phenomenons of social life. We can distinguish at least three different groups of standpoints from which it is possible to analyse this phenomenon. The analysis can be done - from an object related view; this is the area of design, construction, architecture, urban planning etc. An important role is played by quantity and quality charakteristice of the housing stock; - from a social point of view; this includes for instance the human rights altitude (everyone should have a decent home...), the relation of social status to housing, the social consequnccs of homclessncss etc. - from an economic point of view; this means for instance analysis of market relations in housing, alocation of factors, the influence on investment, on the construction industry, on economic growth, on employment etc. All these points also play an important role in the formulation and choise of housing policy. Every point has to be taken into account in an appropriate manner to avoid errors and biases. But it is an extraordinarily difficult task to achieve it. And this is also the reason, why there is such a variety of opinions concerning housing p olicy in general and concerning what the necessary steps to take in the near future arc, in particulare. For the most pait,thc different suggestions are based on contradictions between tiic social and economic evaluations. For the social attitude the main point is social justice, a term quite unclear with only a tentative meaning. For economists the central goal is to strive for efficiency. There are many questions, which arc not solved yet, for instance what is the efFcct of social justice on performance and efficiency, especially in the dynamic sense, and how does economic efficiency act om social justice. Those who stress the social standpoint often ignore economic consequences. On the other hand, there is also the danger of stressing economic efficiency thereby underestimating social factors. This contribution caanot deal with the whole range of probléme s involved; it only concentrates on some economic issues. We must bear in mind that economic factors alone cannot explain the whole problem, they can only present a partial basis for making decisions concerning housing policy. Nevertheless, every step and every decision which ignores economic consequences causes losses, of which we have to be aware, because they involve a lower level of output for the economy and also a lower level of consumption for the society as a whole. This can raise substantial problems in a society, which sufTers from the unsatisfied basic requirements. There is a good reason to think, that one of the main problems which the Czech economy will have to face will be a shortage of housing stock, expecially in some ccters. Demand exceeds supply. Waiting lists are the consequence. Despite of this, a fall in housing construction takes place. This is particular evident, if one considers the decline in housing starts. The decline is so sharp, that the result will only be a deterioration in the average housing conditions of the population in our country measured by such indicators as the number of dwellings per 1000 inhabitants. The number of housing starts is tsv.v so low, that the starts cannot compensate

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WORKSHOP Я5 ECONOMICS к BUSINESS ACTIVITIES

the dwellings which drop-out, from habitation, taking place every year. The main reason for the decline is our government's housing policy.Two years ago, the government declared, that the effort would be made to apply market conditions to housing and to bring rents and prices of dwellings and houses close to a market determined level.Hut according to declaration No 17G/93 by the Ministry of Finance of the Czech republic rents for council and private dwellings (with some insignificant exceptions) are strictly regulated. The yearly amount of rent for 1 in2 of useful floor is limited to 72 Kč. With regard to payment for equipment the average rent for 1 m2 amounts to about 80-90 Kč. On the other hand, average building cost for 1 m2 of useful floor nowadays comes close up to 10 thousands Kč. This means, that the average rent for one year equals less than 1% of the building costs. As some results of research work have showed, the full real costs of using a dwelling for one year are at least 2,7% of the building costs (1% for amortization during a lifespan of 100 years, which is twice the lifespan for buildings according to our tax laws, about 1,5% for maintenace and repair and at least 0,2% for administration costs). This relation holds for the actual price level, not for historical prices, which are inappropriate for such a calculation. For repair and rebuilding landlords have to pay present costs, not historical. So i( makes no sense to calculate relations from historical prices, as our Ministry of Finance does. On this point economic calculations differ substantially from accounting and taxation orders. With regard to the fact, that according to declaration No <I5/6<I tenants have to bear some maintenance and repair costs, the real average cost for the landlord of using a dwelling for one year amounts to about 2,'l% - 2,5% of the actual building costs. This means that tenants bear only a fraction of real costs of the housing. The rest must be settled by the landlord from his own funds. Every year he suffers an inevitable loss, the amount of which is proportional to the size of his housing property. It is no surprise therefore, that not only is there little incentive for building rental dwellings (rents for dwellings built without the support of public funds and authorized after june 1993 are not limited by declaration 76/93), but that there is an opposing incentiv to transform rented dwellings into rooms for business purposes. New houses are built mainly for owner occupation (one and two family houses, residential buildings for housing associations). If local authorities build new dwellings, they must be willing to cover the loss from housing property by other rcccips. There are some fixed ideas, that this ptoblein can be solved by organizing some special form of saving, by mortgage loans or by cxhortaions to local authorities to do more for social housing. But these can only be supplementary means. A thorough analysis leads to the conclusion, that there arc only two possibilities. One is a full liberalization of rents, the other is the extensive support for housing construction from public funds, especially from the government budget. It is impossible to limit rents to an extraordinary low level and hope housing conditions will improve without massive government subsidies. The best way, perhaps, is to liberalize rents, to help households willing to care for their housing and to take measures to provide housing for sick and disabled persons. Rent control not only causes inefficiency, but it even does not act in favour of the poor, especially in the long run. An economy is an intricate system and often taking a measuse which seems to support the desired result acts in the opposite direction.

This research has been conducted at the Department of Construction Management & Economics us pari of the research project "Housing policy, slarlints and consequences" and has been supported by CTU grant No. 2098.

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WORKSHOP 05 ECONOMICS fc IIUSINKSS ACTIVITIES

RECOVERING FINANCING IN CZECH REPUBLIC

F. Fi-eibp g

CTU. Fac. of Mechanical Eng.. Dcpt. of Machinery Enterprise Management Horská Л, 120 00 Praha 2

Key words: firm crisis, recovery analysis, decision process

The Czech firms have not been developed in a market environment. They have been without signals and standards which would have forced them to adapt and to consolidate their economic and financial position. It is therefore necessary to look for and to support ways that could lead to the financial and economic recovering of the firms.

Solving the firms crises, their recovery, seems to be therefore a vital question not only for owners but also for all participants in the firms activities, not lo mention creditors, owners, management and government.

Czech firms need unconditional recovery. They need capital investments and cnterpre-neour concepts including systems of management and control.

Primary implementation of voucher privatisation in our economy however, could not engender these effects. New owners [investment funds] cannot substitute real owners both in providing capital and controlling firms business plans.

Recovery presents a very broad and complex decision process which can be divided into three steps. Introductory step of the decision process concerning recovery must be the analysis of the causes of the financial crises.

The second stage is the verification of suitability for recovery. Ways arc chosen that enable the removal of defects and bringing back profitability and financial equilibrium. The subject of the analysis arc all factors determining performance and efficiency of the firm: competition ability, appeal of the market, capacity exploitation, cash-flow, profitability, management of the firm, assets and capital structure. If the firm is suitable for recovery then an arrangement for restructuring the firms activities and for the corresponding financial solving must be generated. The result is a concept determining the objectives and goals of recovery, the terms and material parameters of the particular arrangements, the effects of these arrangements and the need for capital and the means of covering it.

The last step of the recovery decision process is acceptance analysis. Acceptance of the final concept is subject to many variables such the likelihood of successful completion, the disposability of good recovery management and the disposability of Financial resources, willingness to provide these resources, flexibility of organisation structure, and the time horizon of gaining profitability and financial equilibrium. The whole recovering cycle depicts the next chart:

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WORKSHOP 95 HCONOMICS к. HUS1NRSS ACTIVITIES

A n a l y s i s of the causes of r e cove ry

L i q u i d a t i o n

Ana ly s i s of p o s s i b l e ways of recovery

Concept of r ecovery

A n a l y s i s o: r e c o v e r y a c c e p t a n c e

.-.=cover/ -H olar .

Recovery decision in the Czech economy will be primary affected by the magnitude of the recovering needs, the lack of financial resources, the low quality of recovery management and the fixed firms organisational structure and the motivations and attitudes of the main participants - bank creditors, government, owners.

The question of financial recovery of firms is in the Czech economy very real. The primer reason is huge financial crises in plenty of the small and large firms. Some these firms arc without perspectives and must be liquidated, however the most that they can reach by means of the appropriate recovering policy up to the competitive ability.

912

WOH KS ПОР 95 ECONOMICS fc BUSINESS ACTIVITIES

INTERACTIVE SIMULATION MODELS AS A TECHNIQUE

FOR RISK CALCULATION V. Beran

CTU, Fac. of Civil Eng., Dept. of Constr. Management & Economics Tliákurova 7, 166 29 Praha 6

Key words: simulation, risk, construction management, duration

Engineering projects occasionally fail to perform their intended functions including rare instances of collapse or only poor functioning of project structures or project economic results. In this light, risk is generally implicit in all engineering projects. Most planning and design of engineering projects is accomplished without the benefit of complete information. Under such conditions it is not technically or economically feasible to assure an absolute "safety" of engineering projects. The planning and development of a major project are a complex exercise in the management of risk.

Managers and decisions-makers solve problems on the basis of information that is often insufficient, inaccurate or unsuitable.

In other words, risk management concerns ascertaining that the minimum (worst) supplies condition will remain adequate (by negotiated margins) under a maximum demand requirement that constitutes minimum supply and maximum demand conditions. A subjective traditional approach to the minimum and maximum of supply and demand is difficult to quantify because the level of risk cannot be assessed with "hard and fast lines".

The spectrum and diversity of possible applications are very high. Risk Management of the time and costs scheduling remains probably one of the most useful areas of commercial engagement. The analysis of risk, sensitivity, uncertainty of variants comparison is going to be the main topic at the advanced stage of management projects. Most of the problems could be solved by means of simulations. However, the traditional deterministic formulas for calculation of a construction manufacturing look sophisticated and mathematically advanced, this kind of calculation cannot create significant signals for management about a risk situation. This experience brings even simple simulations to the foreground. Under the combination of uncertain influences and their differences, positive and negative deviations are springing up. Risky contracting and economical failure are the consequence. This information gap appears even with expensive computer software packages for time and cost scheduling.

The example in time and cost management might be a good illustration of one influencing factor - risk in the speed of construction changes the stability of contracted duration. The technological cause in this example is only one source that creates risky duration. The question is sensitive of possible additional directions that may lead to (new) risks. If there exists another additional risk, there will be a recalculation (new simulation of duration) necessary. Risk creating events can operate in some simulation steps compensatory, but in some simulation steps they can operate even contradictory. The result is an excessively risky sequence of duration. In our example, and unstable volume of construction work is (given through costs) could be used as a materialized illustration for such situations. The

913

WORKSHOP 95 ECONOMICS & BUSINESS ACTIVITIES

example of simulation of time and cost simulation lias been calculated and sonic results will be presented. The start and end of the construction job has been characterized by oscillation.

References: [1] BERAN, V.: Elektronické zpracování dynamických harmonogramů. Praha, 1994.

This research /ins been conducted at the Department of Econimics and Management in Construction Industry and has been supported by CTU grant No. 12650.

Propočet rizik zahájeni a ukončeni práci subdodavatele

Rizika včasného /ahá|ení а ukončeni

prací

Smluvních 1000 pracovních dnů

914

WORKSHOP 95 ECONOMICS к BUSINESS ACTIVITIES

ABSORPTION OR VARIABLE COSTING METHODS?

K. Mac ík

CTU, Fac. of Mechanical Eng., Dcpt. of Machinery Enterprise Management Horská 3, 120 00 Praha 2

Key words: price, profit, returns, costs, absorption costing, variable costing, direct costs, fixed costs, variable costs, transformation matrics, overhead charge, contribution margin

The beginning of this paper shows the connection between the price and costs of goods in a market economy. The emphasis is on the condition that the price of a product is created on the market by interactions between buyers (consumers) and sellers (producers). The behaviour of consumers and producers is characterised from the mathematical point of view by the demand function and supply function. The interaction might lead to a market equilibrium situation, when the demand and supply after certain steps meet. In entrepreneurial practice ii is necessary to abandon the idea of determining prices with respect to the achieved costs of products manufactured by a firm, on condition it is not a monopoly producer. But even against this monopolist endeavour there exist antitrust acts and antitrust policy regulated by the state. Generally it is important to proceed from the assumption that the price of a special product is for a producer a given value and he must try to influence by his costs (he best achieved profit.

At present we can often see that the enterprise management is only unsatisfactorily or not at all informed about the manufacturing costs of a single product. This tendency is more obvious in those firms implementing a heterogeneous production programme. It cannot be generally stated that the producer docs not pay any attention to the determination of unit costs, that means to the costing problem. The procedures of fixing these costs were very often rather formal, without any relation to actual costs reported in the accounting system. Neglecting of this can be explained by the prevailing att i tude very often present in conceptual considerations, namely that a firm is more interested in final outcome than in profitability of single products.

In the Czech entrepreneurial costing practice the full cost system (absorption costing) prevails. The accounting system is working with cost types, the cost accounting system needs for costing procedures a transformed costs structure called calculation costs. This costs structure is presented by direct costs and indirect costs (overhead costs). These overhead costs must be allocated to all types of manufactured products. The greater the variety of produced goods the greater the problems with the allocation of indirect cost, which arc common to some or all types of products, and to every single type of product unit. It means a tendency of absorbing all the costs, whether they are caused by the given products or not, to each type of product. Thcrcfoic this procedure is called absorption costing.

In the paper, transformation of cost types (costs of inputs) into calculation costs is introduced by a transformation matrix, that formulates a theoretical requirement of an ideal result of the applied costing procedure. In practise, we arc mostly far behind this ideal outcome, but it is possible to get closer to it; what depends on the complexity and heterogeneity of the production programme. A criticism of one of the most frequently used costing procedures by overhead charges in Czech firms is presented. This criticism is

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WORKSHOP 95 ECONOMICS fc BUSINESS ACTIVITIES

completed by recommendations how to improve and give more precision to the overhead charge method within its limits of utilization.

In case of homogeneous productions programmes, it is possible to implement for determining of costs per unit a '"dynamized" costing procedure which takes into account the fluctuation of production capacity (employment level). With increasing production capacity, utilization of the fixed costs per unit decrease. This can be solved eithc. by differentiation of overhead charges for each capacity utilization level, or by cost analysis working with cost functions.

All the above mentioned procedures, that means overhead charging and dynamic costing arc working with full costs. Besides this approach in the field of costing method there exists some methods using only a part of the costs. This approach requires, as well as the dynamic costing approach, the differentiation of costs from the standpoint of their relationship to product and time. This concerns the fixed a variable costs. Variable costs depend directly on the size on manufactured goods, because they arc caused by them, while fixed costs arc a function of time. The present problems are effected just by recognizing this two groups of costs, because this is the precondition of utilising costing methods of incomplete costs called shortly "variable costing technique" or "direct costing method".

The variable costing method is very suitable for decision making on the production programme, its structure and analysing profitability of each kind of product. This procedure is closely connected whit the contribution margin covering the total fixed costs and earning profit. The contribution margin per unit determines the volume of products a company must manufacture to achieve a desired profit. An example demonstrates mistakes that may be caused by wrong decisions omitting products from the production programme since they bring a loss though they still contribute to covering a part of fixed costs.

At the end it is stated that from the standpoint of Czech companies who have to choose between absorption or variable costing processes, both of the approaches arc useful, each of them for different purposes The absorption costing approach is preferred mainly for valuation of inventories of finished goods and goods in process, the variable costing approach prevails in decisions that must be made about the manufacturing programme, especially that of the structure of produced goods and their sizes.

References:

[1] MACÍK, K.: Jak kalkuloval podnikové náklady, Montanex, Ostrava 1994.

[2] MACÍK, K.: Moderní kalkulace nákladů, Vydavatelství ČVUT, Praha 1994.

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WORKSHOP 95 ECONOMICS k BUSINESS ACTIVITIES

COST-VOLUME-PROFIT ANALYSIS (BREAK-EVEN ANALYSIS)

UNDER RISK

M. Písek

CTU, Fac. of Mechanical Eng., Dept. of Machinery Enterprise Management Horská 3, 120 00 Praha 2

Key words: profit, break-even-point, random variable, risk

Cosl-volume-profit (C-V-P) analysis (sometimes called break-even analysis) is used in many companies to determine what effects any changes in the compamy's selling prices, costs, and/or volume on income will have in the short run.

Early models developed to assist management in understanding the relation of costs to volume and profit (C-V-P) of existing operations or to provide projections of profitability for a new product (single product C-V-P analysis) took the form of a deterministic relationship. In the linear case (linear C-V-P analysis) some limiting assumptions are made:

1. Unit selling price, unit variable cost and fixed costs per period remain constant. 2. The number of units produced equals the number of units sold so that costs arising

from unrealized supply - liquidation or removal of surplus inventory - are neglected.

Under these assumptions it is quite easy to find - mathematically solving a linear equation or graphically drawing a break-even chart - the break-even point as that level of operations at which a company realizes no net income or loss.

Employing the basic (linear) C-V-P model in business decision making focuses attention on the future which naturally embraces uncertainty of the variables in the model. In the simplest case, only the selling price per unit is regarded as a random variable with a certain probability distribution. Then also the break-even point and the corresponding profit become random variables. The relations between these random variables define - in terms of probability theory - the transformations of the original random variable - selling price -into two new random variables - break-even point and profit - with their new probability distributions.

The basic problem lies in the subjective construction of the probability distribution of the selling price. It seemis reasonable to assume that the selling price takes on values in a finite interval. Then various probability densities (uniform, triangular, beta) can be used for modelling the selling price probability distribution.

The probability distribution of the profit enables us to find two important measures of risk: the probability of not attaining the goal value of profit and the dispersion of profit. They both play an important role in decision situations when management - in addition to maximizing profit - seeks to avoid excessive risk.

917


Further, management may ha%'c different risk attitudes (risk-averse, risk-neutral and risk-seeking). In such a case, a utility function reflecting management's attitude toward risk might be used instead of a profit function.

Finally, the analytic approach to C-V-P analysis must be replaced by Monte Carlo simulation requiring computer assistance in more complicated decision situations, when, for example:

• more variables in the C-V-P model arc random variables,

• their probability distributions arc more complicated,

• the cost function is no more linear, but progressively or degrcssivcly increasing, • not the single product, but the multiproduct C-V-P analysis is needed.

t

91S


APPLICATIONS FEATURES OF THE HOUR OVERHEAD

TARIFFS METHOD

M. Zralý

CTU, Fac. of Mechanical Eng., Dcpt. of Machinery Enterprise Management Horská 3, 120 00 Praha 2

Key words: Cost accounting methods, overhead costs

The companies of the manufacturing industries in the Czech Republic usually produce a great variety of goods or final products composed of a great number of parts.

In that case the absorption costing dominates. The variable costing procedures may play only a complementary role.

Most companies tend to transform cost accounting methods and techniques from these, based on the set of overhead cost drivers mostly used direct labour as the cost driver to another ones. However, which one of cost accounting method should be chosen? There is a very limited number of methods and techniques to be taken in account that really tends to improve the cost accounting process. According to research work /LI / , Hour Overhead Tarifis (HOT) Method there seems to be only one efficient solution in the area of pre-production and production stages. Now, we have been working on HOT Method applications in some Czech manufacturing companies /L2/, to confirm the theoretical expectations in practise.

The basic assumption behiirl the Hour Overhead Tariffs Method is that a portion of the overhead costs does not change essentially:

• with changes in the structure of usually produced products,

• until the production capacity of the centre is not overstepped.

It is based on the recognition, that the decisive part of overhead costs is basically (entirely or practically) fixed in the one year period, which is meaningful in this context. The examples of the first group of costs can be depreciation, heating, lighting, leasing, assurance. The examples of the others are overhead wages (it include mostly all wages and salaries at present), other energy consumption, costs of repairs, costs of training, communication costs.

The fundamental consideration is based on the fact that the existence of a particular part of a company, for example a centre, is connected with particular overhead costs. Most of these company's parts (centres) are directly linked to product planning, to product design, to preparation of technical or sales documentation of the product, to product manufacturing or to the other activities, which are needed directly to the product. In all these centres the HOT Method can be effectively used. The costs of these centres should be divided among the products, which go through these centres, according to the time spent in the centre. The budgeted as well as real cost values of these centres are normally known.

Then the primary problem, that has to be solved, is how to determine the capacity of the centre to which the overhead costs should be related. The capacity is normally expressed in the hours of work, which the centre offers to producing goods or services. Dividing the

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sum of the overhead costs through the hour's capacity of the centre, the required hour overhead tariff is obtained.

The capacity utilization in relation to the MOT value in moie levels, e.g. for 70consid-ercd useful.

Note: The capacity may be expressed in man hours or in machine hours, according to which the capacity of the centre is limited.

The grace of this concept is in the simplicity of the concept, in the simplicity of implementation and in the perfection of its economic influence.

To determine the planned HOT, you really need to use only the budgeted overhead costs of the centre, which are normally available. To confront it to the real values, you can use thc accounting figures. You may take the budgeted or recorded costs as one number which means the sum of overhead costs of the centre and to divide it by the number of working (man or machine) hours, that arc expected to be worked out during the period, you have in mind. Note: Usually one year's period is taken in account.

To follow the development of the HOT of a single centre, it gives more managerial information of the cost development in the centre. It can also concluded in decision to close the centre in such a case that the price of purchased goods is lower than the costs of services or products, which are produced in that particular centre. It offers a very efficient way of motivation of the head and employees of the centre.

Summary: The HOT Method: 1. Is closely integrated to the organizational structure. The centre structure is a basis for which HOT Method is fitting. 2. Is tightly integrated to budgeting and accounting. It utilizes the figures provided with these information circles. 3. Is tightly connected to the capacity planning and capacity utilization. It offers also to he prepared to more levels of expectation of capacity utilization, -t. Requires only very few additional data to he prepared in comparison to what is regularly done in a company. That means it chiefly utilizes prepared and collected data from the other information circles (budgeting, accounting, capacity planning) to its information purposes. 5. May be used in pre-manufacturing as well as manufacturing processes. 6. Links product costing firmly to the centre costing in both the ex ante and the ex post view. The final conclusions of the consequences of the HOT Method application could be done after next two or three years. This time we observe as the minimal time period, which is necessary, any of the concluding evaluation of application results which could be done with respect to the essential effects and potential troubles which application causes. However, we expect positive estimations.

References:

[1] VYSUŠIL, J.: Střediskové hospodářství (Profit Centre Economics), Praha 1992. [2] MACÍK, К. - FREIBERG, F. - ZRALÝ, M.: Koncepce kalkulace pro ZPS Zlín (Concept

of Cost Accounting in ZPS Zlín), 1993. [3] BROMWICH, M.: Readings on Management Accounting, London School of Economics,

dpt. Accounting and Finance, 19915.

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WORKSHOP 1)5 ECONOMICS As BUSINESS ACTIVITIES

MODELS AND SOFTWARE FOR MANAGEMENT OF PRODUCTION

IN THE CONSTRUCTION INDUSTRY J. Klvni'm, Л. Junek, A. Knčnbn, J. Kučerová, D t Vytlačil, M, Sum

CTU, Рас. of Civil Eng., Dcpt, of Engineering Informatics Thákurova 7, 1GG 29 Praha G

Key words: multi-level management, system of models, software for management, multi-criterial decision making

The situation in the field of software and models suitable for management of construction cnterprices is rather complicated and not satisfactory. There exist some isolated and common known models used by most construction enterpriccs like personal agenda, budget preparation, inventory models, preparation of construction process or network models (CPiYl, РЕНТ), but the models are not interconnected and do not reflect the specific phenomena of the building industry and construction entcrprices. To the specific phenomena belong:

1) Existence of multilevel, hierarchical management. 2) Existence of different optimisation criteria. 3) Localisation of building production on a large territorium. Big construction enterprices have 3-4 levels of management. The top level management

has its own tasks that are more long-term and strategic ones. Most criteria are formulated as maximization (e.g. of profit, capital etc.). The top management formulates its problems expressed mostly in monetary units.

The lowest level management is that of managing construction process in site. We are again meeting multicriterial decision making, but in this case a short-term one. Most criteria are in this case formulated as minimization (e.g. of costs). The lowest level management formulates its problems expressed frequently in physical units (m3,1, etc.). The middle-level management (1-2 levels) has its goals and 'asks not clearly specified. Different enterpriccs solve the problems of midle-levcl management by different ways.

The suitable models and software arc beeing developed. They reflect the existence of multicriterial strategic and short-term decision making and control with respect to problems of middle-level management. The models arc intcrconectcd in order to create a model svstcm (system of models).

The localisation of building production on large territorium needs software with utilization and interconnection of LAN and WAN.

The information technologies grow and evolve very quickly and bring new solutions in information support of managing firms. In addition construction firms in the Czech Republic seek improvement of their information systems. In contrast to Western countries, where rules of market are stable, emphasis in Czech firms is on changes in bookkeeping and new relations among subjects of the market. Therefoie in addition to establishing computer systems as an office tool, bookkeeping and financial sj items have been made a priority.

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WORKSHOP OS KCONOM1CS fa MUSINFSS ACTIVITIES

Systems for creating offers, budgets and calculation costs are also in great demand because national products abide by Czech laws, habits and terminology, they are prefered to foreign products, Although some foreign programs (cg. Q-BIDS, Q-AVA) have tools for linking with predecessors in meaning creation and developing projects (CAD systems), Czech programs (Callida, Porings, Kanasta, Akalk, К ros and others) have a strong backround in supporting databases, which include items of building works, materials, workers, machines etc, The problem, which these products shall override, is in incompatibility methodology of budget creation and I he form of sorting building production with FJJ countries where wc want to belong.

The next group represents programs for lime planning, cost management, resource levelling and control, risk analysis. These products are called "Project Manager" (Open Plan, Primavera, Artemis, Super Project, Time Line, Microsoft Project, А ВТ Project Workbench, Tcxim Project, Power Project) and we can expect their rise on the Czech software market with the rising competitive environment. They arc useful not in construction industry but also in all kinds of planning and managing. Formerly, there were some bigger systems under the supervision of COCOM, because these product could be used in the army. In the West countries they arc very popular and contemporaneous. They are so friendly and have such strong tools that there is no comparison with the Czech one. It can be used at all levels in managing firms. It can help in financial planning, allocation and levelling resources, control production etc. A disadvantage could be their high price. Czech programs have the advantage of easily linking to some Czech products from previous groups. As with the calculation programs, tlicr have been some Czech programs with such a base net and typical graphics technology process in construction (Poring, Contcc and others).

Construction firms would not have problems with the decision of which product is best for them, but could have an integration of these programs with the one for managing a firm. The compatibility depends not only on the ability to import/export data among programs but also on the difference in philosophical principles on which they are based. Therefore some Czech systems (Porings) have ambitions, by the modular way, to solve all works in construction firms including bookkeeping, managing stores and personal systems.

One part our work is devoted to the investigation of effectiveness of the investments from the point of view of investors - feasibility study of project as well as construction company -investments to technology, equipment. Feasibility study is a tool for evaluation of projects, which includes location and site selection, production and supply programme, technology, equipment, civil engineering, manpower requirements, implementation scheduling, financial analysis. It is an important stage of decision making in the project selection process.

The COM FAR is a computer program for financial evaluation of projects based on Manual for the Preparation of Industrial Feasibility Studies (UNIDO publication). This Program allows us to do detail financial analysis and is used in some banks in Czech Republic. Disadvantage of this program is its high price and cumbersome changes in input values.

This research has been conducted at the Department of Engineering informatics as part of the research project "Models and Software for Management of Production in the Construction Industry" and has been supported by Fac. of Civil Eng. grant No. 2047.

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WORKSHOP 05 ECONOMICS к BUSINESS ACTIVITIES

CHANGES IN THE VOLUME AND STRUCTURE OF INCOMES UNDER

ECONOMIC TRANSFORMATION IN THE CZECH REPUBLIC

H. Pačesová

CTlř, Fac of Mechanical Rug., Pept. of Machinery Enterprise Management Horská 3, 120 00 Praha 2

Key words: personal income, tax reform, inflation, households

The first four years of economic transformation have brought significant changes in the amount and structure of incomes, expenditures ans savings of the population. The most iiifliiencong factor of these changes has been then process as a consequence of price liberalization and tax reform. Inflation influenced the incomes substanially during the year 1991, the first year of liberalization. Incomes declined significantly in real terms owing to this factor, but within a very short period this decline stopped. Since 1992 the income per person has begun to grow in real terms and by the end of 1993 it had nearly reached the initial 19S9 level. The tendency towards lower fluctuations and more fluent development in the last two years has hinted the possibility that the initial level of income in real terms will soon be attained.

The real value of expenditures is lower than that of incomes, due to prudent savings inclinatoins of Czech people. The savings rate grew in both the Czech crowns and foreign currency deposits. The macrocconomic results of development in this field arc positive.

Consumer prices had already started grow in the second half of 1990, due to the removal of the negative turnover tax. This was a very important step towards normal price relationship and to the subsequent introduction of a Value Added Tax. The most dramatic impact on consumer prices was a sequence of price liberalization steps. In this case the prices of food went up almost from the first day. The prices of non-food goods grew gradually along with renewed demand. The population was acquainted with liberalization measures in advanced and expected the price increases. It caused cumulation of goods in the households. The third set of remarkable price increase took place after the introduction of new tax system. Growth was higher than the preliminary calculations had shown - partially due to ignorance, partially due to speculations. But it is specific for the situation in the Czech economy tha prices stabilized very soon after the measures were implemented, usually within a month. In general, the main transformation measures in the Czech economy affecting price level were realized, and there are some presumptions that future development in this field will be more smooth (similarly to the situation in 1992).

In individual households, the process of differentiation has taken place. Incomes and expenditures in families with children and pensioners' households dropped more than in the other families. This process is observed in some households of employees, farmers and pensioners. On the other hand, some groups of households grew rich. The missing data about rich households of entrepreneurs and managers does not allow us to fully examine the process of differentiation in personal income and expenditures. The lower growth of

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these indicators in all types of examined households in comparison with the grows of total incomes and expenditures shows that there is a group with higher incomes, not included in family accounts. The same is confirmed by the rapid increase in high deposits at Czech Savings Banks over the rate of low deposits. Therefore we have more information about growing poverty on the one hand than about the growing wealth on the other. New sources of data for these purposes should be looked for in order to avoid a one-sided analysis of the development in the household sector.

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WORKSHOP 95 MATHEMATICS

NUMERICAL SIMULATION OF PULSATILE FLOW

BY THE SECOND ORDER SCHEME P. Burda, J . Kořenář*

CTU, Fac. of Mechanical Eng., Dcpt. of Mathematics Karlovo nám. 13, 121 35 Praha 2

*Acad. Sci. Czech Rep., Inst, of Hydrodynamics, Dcp. of Biomechanics Podbabská 13, 166 12, Praha 6

Key words: Navier-Stokes equations, pulsatile flow, Crank-Nicolson scheme

In the papers [1-3] we reported on the numerical solution of pulsatile flow in blood vessels corresponding to the values of the Reynolds number up to Re = 600. For the time discretization we used quite effectively the semiimplicit scheme. In 1994 we have simulated the flow in the aorta where the Reynolds number is considerably higher (Re и 2000). Also the boundary conditions in the inlet and outlet are more complicated. To get reasonable numerical solution we use methods with better stability properties.

We consider the problem governed by the Navier-Stokes equation

^ + (V • V)V = - ig rad p + vAV . at p (1)

For the time discretization we use a modification of the Crank-Nicolson scheme (more details can be found e.g. in [4])

V" _ vn + 1^уЯ+1 . v ) v / n + i + (Kn , y ) V n + l v / )П | = 1„{ду»+« + Д1/»}, (2)

д pn+i _ ± VV", (3)

yn+\ = у" - r -grad ; , " + 1 (4) 1p

In each time step the system of equations (3), (4), (5) is solved iteratively.

ftxial Uelocity Profiles PERI0D:13, PHňSE:Z32* t= 14.562 Is] SCALE .05 x

Fig. 1: Velocity profiles at 232° (i = 14.56sec.)

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WORKSHOP 95 MATHEMATICS

The results relevant to this approach have been published in ['1-6], and reported on the conferences (7-10]. One of the results is shown on the Figure 1.

As concerns numerical solution of the flow in artificial vascular grafts results can be seen in [11, 12]. The results of experimental measiiremcns have been published in [13].

References: [I] BURDA, P. - KORENÁR, .1.: Numerical solution of Navicr-Stokcs equations for con

stricted pulsations, Conf. GAMM '93, Dresden, ZAMM 74, No. G, 1994. [2] BURDA, P. - KORENÁR, J.: Numerical simulation of pulsatile flow in the aorta under

symmetric obstacle (Czech), Proč. Sem. "OAPMT", Inst, Therm. - Prague, 1994, 9-10.

[3] BURDA, P. - KORENÁR, J.: Numerical simulation of pulsatile flow in the aorta, Proc. Workshop 94, Prague, 1994, 21-22.

[4] BURDA, P. - KORENÁR, J.: Numerical simulation of constricted Jlo w in the aorta, Proc. of 5-th Internát. Conf. Biomechanics of Man 194, Benešov, 1994, 9-12.

[5] BURDA, P. - KORENÁR, J.: MAC scheme in the numerical solution of pulsatile flow (in Czech), Proc. Colloquium "Dynamika tekutin", Prague 1994, 9-10.

[G] BURDA, P. - KORENÁR, J.: Second order discretization of pulsatile flow in a constricted lube, to appear in Proc. Conf. Num. Modelling in Cont. Mcch. - Prague, 1994.

[7] BURDA, P. - KORENÁR, J.: Numerical simulation of constricted pulsatile floru in the axially symmetric model of the aorta, GAMM 94 Conference, Braunschweig, April 1994.

[8] BURDA, P. - KORENÁR, J.: Splitting technique in the numerical solution of pulsatile flow, Book of abstracts of the Intern. Symp. Modelling 94, Prague, Aug. 29 - Sept. 2, 1994.

[9] BURDA, P. - KORENÁR, J.: Numerical simulation of Navier-Slokes equations for pulsatile flow in constricted blood vessels, Seminar IMAMM 94, Rybník, July 1994.

[10] BURDA, P. - KORENÁR, J.: Solution of the Navicr-Stokcs equation by the second order implicit scheme with splitting (in Czech), Seminar "PAANM", Bratnkov, June 1994.

[II] SKALÁK, Z.: Numerical analysis of the flow through corrugated channels, Proc. of 5-th Internát. Conf. Biomechanics of Man '94, Benešov, 1994, 132-135.

[12] SKALÁK, Z. - KUČERA, P.: Numerical analysis of the flow of newtonian fluids in rigid corrugated lubes, GAMM 94 Conference, Braunschweig, April 1994.

[13] KONFRST, J.: LDA measurements of pulsatile flow in a model of vascular graft, Proc. of 5-th Internát. Conf. Biomechanics of Man '94, Benešov, 1994, 72-75.

This research has been done at the Dep. of Mathematics of the Faculty of Mcch. Eng. of CTU Prague, partly under the project "Numerical simulation of pulsatile flow in artificial vascular grafts with singularities", which has been supported by the CTU grant No. IJ28167 and partly under the project "Simulation of pulsatile flow in artificial vascular grafts", supported by the grant No. 1121002 (Fund for Development of Universities).

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CZECH TECHNICAL UNIVERSITY IN PRAGUE TECHNICAL UNIVERSITY ...

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