Godina (Volume) 14 Broj (Number) 4, Oktobar-...

http://www.mf.unze.ba/Masinstvo

Godina (Volume) 14 Broj (Number) 4, Oktobar- Decembar (October- December) 2017.

173

ISSN 1512-5173 http://www.mf.unze.ba/masinstvo

MAŠINSTVO ČASOPIS ZA MAŠINSKO INŽENJERSTVO

JOURNAL OF MECHANICAL ENGINEERING Godina (Volume) 14, Broj (Number) 4, Zenica, Oktobar – Decembar (October – December) 2017.

Uredništvo (Editorial): Fakultetska 1, 72000 Zenica Bosnia and Herzegovina Tel: +387 32 449 143; 449 145 Fax: +387 32 246 612 e-mail: [email protected] [email protected] [email protected]

Osnivač i izvršni izdavač (Founders and Executive Publisher): University of Zenica Faculty of Mechanical Engineering Fakultetska 1, 72000 Zenica Bosnia and Herzegovina Recenzioni odbor (Review committe): Dr. Jusuf Duraković, Dr. Mirsada Oruč, Dr. Sabahudin Jašarević, Dr. Zlatan Talić,

Glavni i odgovorni urednik (Editor and Chief): Prof. Dr. Sc. Safet Brdarević

Časopis izlazi tromjesečno (The journal is published quarterly)

Urednički odbor (Editorial Board): Dr. Safet Brdarević (B&H), Dr. Jože Duhovnik (Slovenia), Dr. Vidosav Majstorović (Serbia), Dr. Milan Jurković (Croatia), Dr. Sabahudin Ekinović (B&H), Dr. Gheorge I. Gheorge (Romania), Dr. Alojz Ivanković (Ireland), Dr. Joan Vivancos (Spain), Dr. Ivo Čala (Croatia), Dr. Slavko Arsovski (Serbia), Dr. Albert Weckenman (Germany), Dr. Ibrahim Pašić (France), Dr. Zdravko Krivokapić (Montenegro), Dr. Rainer Lotzien (Germany)

Tehnički urednik (Technical Editor): Prof. Dr. Sabahudin Jašarević Štampa (Print): Štamparija Fojnica d.o.o., Fojnica Uređenje zaključeno (Preparation ended): 31.12.2017.

Časopis je evidentiran u evidenciji javnih glasila pri Ministarstvu nauke, obrazovanja, kulture i sport Federacije Bosne i Hercegovine pod brojem 651. Časopis u pretežnom iznosu finansira osnivač i izdavač. Časopis MAŠINSTVO u pravilu izlazi u četiri broja godišnje. Rukopisi se ne vraćaju

The Journal is listed under No 651 in the list of public journals in the Ministry of science, education, culture and sport of the Federation of Bosnia and Herzegovina. The Journals is mostly financed by founder and publisher. Frequency of Journal MAŠINSTVO is 4 issues a year. Manuscripts are not returned

Časopis objavljuje naučne i stručne radove i informacije od interesa za stručnu i privrednu javnost iz oblasti mašinstva i srodnih grana vezanih za područje primjene i izučavanja mašinstva. Posebno se obrađuju slijedeće tematike: - tehnologija prerade metala, plastike i gume, - projektovanje i konstruisanje mašina i postrojenja, - projektovanje proizvodnih sistema, - energija, - održavanje sredstava za rad, - kvalitet, efikasnost sistema i upravljanje proizvodnim i poslovnim sistemima, - informacije o novim knjigama, - informacije o naučnim skupovima - informacije sa Univerziteta,

The journal publishes scientific and professional papers and information of interest to professional and economic releases in mechanical engineering and related fields. In particular, the following topics are treated: - Technology for processing metal, plastic and rubber, - Design and construction of machines and plants, - The design of production systems, - Energy, - Maintenance funds for the work, - Quality and efficiency of the system and the management of production and business systems, - Information about new books, - Information about scientific meetings - Information from the University,

174

RIJEČ UREDNIKA Poštovane kolegice i kolege U četvrtom broju Časopisa u četrnaestoj godini izlaženja (ukupno 56. broj od početka izlaženje) predstavljamo Vam 5 radova raznovrsne tematike. Prvi od njih je „Značaj ispitivanja žilavosti i zamora kod aluminijskih 6xxx legura“ i ukazuje na značaj eksploatacione karakteristike aluminijskih legura koje su sve više u upotrebi. Drugi i treći rad se odnose na komunalne sisteme grijanja gradova koji uslovima štednje energije i smanjenja zagađenja postaju sve aktuelniji čak i u zemljama tranzicije. Treći rad je prenešen sa Naučno-stručnog skupa „Festival kvaliteta“ održanog na Jahorini oktobra 2017. Četvrti rad predstavlja prikaz primjene čelične armature u rješenju jednog problema građevinarstva (Analiza rješenja kosine usjeka primjenom metode armiranog tla, čavljanja i izrade potpornog zida). Peti rad predstavlja pokušaj da se uđe u prostor utvrđivanja motiva kandidata za upis na tehničke studije. U zemljama u tranziciji evidentan je pad interesa kandidata za upis na ove studije, u odnosu na društvene i humanističke. U bloku informacija predstavljeni su pozivi za održavanje četiri naučno-stručna skupa u Bosni i Hercegovini. U naporu da se predstave BiH istraživački kapaciteti na prvoj strani korica predstavljena je jedna laboratorija Mašinskog fakulteta Univerziteta „Džemal Bijedić“ iz Mostara. Na zadnjoj strani korica predstavljena je jedna uspješna firma (skoro svu proizvodnju izvozi) iz drvoprerade. Pozivamo Vas da date svoj doprinos Časopisu Mašinstvo, na Vašu korist, korist struke i nauke.

Vaš glavni i odgovorni urednikProf. emeritus dr. Safet Brdarević

EDITORIAL Dear Colleagues In the fourth issue of Journal in the fourteenth year of publication (total number 56 from the beginning of the exhibition) we present you 5 works of various themes. The first of them is "The Significance of Hardness and Fatigue Testing in Aluminum 6xxx Alloys" and points to the importance of the exploitation characteristics of aluminum alloys that are increasingly in use. The second and third work is related to communal heating systems of cities that are becoming more and more active even in transition countries, with energy saving and pollution reduction. The third paper was transmitted from the Scientific-Professional "Quality Festival" held in Jahorina on October 2017. The fourth paper presents the application of steel reinforcement in solving a problem of civil engineering (Analysis Solution Of Cut Using Methods Of Reinforced Wall, Soil Nailing And Making Retaining Wall). The fifth paper is an attempt to enter the space for determining the motivation of candidates for enrollment in technical studies. In transition countries there is a marked decline in the interest of candidates for enrollment in these studies, compared to social and humanistic. In the block of information, calls were made to hold four scientific and expert meetings in Bosnia and Herzegovina. In an effort to present the BiH research capacities on the first page of the Journal, a laboratory of the Faculty of Mechanical Engineering of the University "Džemal Bijedić" from Mostar was presented. On the back of the Journal, one successful company (almost all production exports) from woodcutting was presented. We invite you to give your contribution to the Journal Machine for your benefit, the benefit of the profession and the science.

Your editor in chiefProf. emeritus dr. Safet Brdarević

SADRŽAJ

1. Značaj ispitivanja žilavosti i zamora kod aluminijskih 6xxx legura Gačo Dž., Hrnjica B., Bajramović E. 175

2. Sistem daljinskog grijanja u Kaknju Kahriman A., Hodžić N,. Ekinović E. 183

3. Komparacija sistema daljinskog grijanja gradova zemalja u tranziciji Mrkić Bosančić M., Gvero P., Ibrulj J., Husika A., Vasković S. 193

4. Analiza rješenja kosine usjeka primjenom metoda armiranog tla, čavlanja i izrade potpornog zida Turčinović N. 203

5. Analiza atraktivnosti studija nauke i tehnologije Brdarević S., Arnaut D. 213

Informacije 227

Uputstvo za autore 232

CONTENTS

1. Toughness and Fatigue Analysis of Al 6xxx Alloys

Gačo Dž., Hrnjica B., Bajramović E. 175

2. The District Heating System in the City of Kakanj Kahriman A., Hodžić N,. Ekinović E. 183

3. Comparative of the district heating system of countries in transition Mrkić Bosančić M., Gvero P., Ibrulj J., Husika A., Vasković S. 193

4. Analysis Solution of Cut Using Methods of Reinforced Wall, Soil Nailing and Making Retaining Wall Turčinović N. 203

5. Analysis Of The Attractiveness Of Science And Technology Studies Brdarević S., Arnaut D. 213

Information 227

Instruction for authors 232

Mašinstvo 4(14), 175-182, (2017) Dž. Gačo, et al.: TOUGHNESS AND FATIGUE ….

175

ZNAČAJ ISPITIVANJA ŽILAVOSTI I ZAMORA KOD ALUMINIJSKI 6xxx LEGURA

TOUGHNESS AND FATIGUE ANALYSIS OF AL 6xxx ALLOYS

Dženana Gačo Bahrudin Hrnjica Esad Bajramović University of Bihać, Faculty of Technical Engineering Ključne riječi: aluminijske legure, žilavost, zamor, rast zamorne prsline Keywords: Aluminium Alloys, Fatigue, Toughness, Crack tip, Crack propagation Paper received: 11.09.2017. Paper accepted: 20.12.2017.

Pregledni rad REZIME Mehaničke osobine svakog materijala igraju veliku ulogu u toku izbora vrste materijala za bilo koji mehanički sistem. Jedna od osnovnih mehanička karakteristika koja je krucijalna za izbor materijala je žilavost. Rad prikazuje neke aspekte problema vezano za žilavost i zamor aluminijskih legura. U radu su također opisane standardne procedure prema ASTM i britanskom standardu prema kojima se opisuju procedure kod analize i određivanja osobina žilavosti i zamora materijala za ove vrste legura.

Paper rewiev

SUMMARY Mechanical properties of every material play important role during material selection for any mechanic system. The main mechanics property which is crucial for material selection is Toughness. The paper present some of the aspects in problems of the toughness and fatigue for Aluminum Alloys. The paper also presents the set of the ASTM anf British Standards which describe procedure in analysing and determining toughness and fatige properties for this kind of the alloys.

1. UVOD Mehaničke osobine predstavljaju osnovni kriterij za odabir nekog materijala u mašinskom sistemu. Pri odabiru jedna od osnovnih mehaničkih osobina prema kojoj se definišu grupe materijala koje ulaze u sastav mehaničkog sistema predstavlja zamor materijala. Zamor predstavlja takvu pojavu u materijalu da nakon određenog broja cikličnih opterećenja material slabi i postaje lomljiv, pri vrijednostima opterećenja koja su ispod dozvoljenih statičkim proračuna [1]. Zamor materijala se manifestira kroz stvaranje inicijalnih prslina, a zatim njihovim postepenim širenjem. Ove prsline se šire postepeno, a nakon izvjesnog vremena postaju osnovni uzrok pucanja i loma struture. Također, u vrijeme konstrukcije mehaničkog sistema od krucijalne je važnosti i spoznaja kritičnih parametara mehanike loma da bi sistema radio bezbjedno. Legure aluminija u upotrebi su zadnjih 100 godina, a posebno u avionskoj industriji od 30-godina prošlog vijeka.

1. INTRODUCTION The mechanical properties of the material are the basic criteria for selection of material in the mechanical system. When choosing a material, the basic mechanical characteristic by which to define the group of materials that constitute the mechanical system, is material fatigue. Fatigue is such a phenomenon in the material that after a certain number of cyclic loadings, material becomes weak and brittle in load values that are below the allowable static calculations [1]. Material fatigue manifests itself by creating cracks, and their gradual expansion. These cracks are spreading in a certain proportion, eventually becoming a major cause of cracking and fracture of the structure. Therefore, at the time of construction of the mechanical system, the knowledge of fracture mechanics parameters is crucial, in order for the system to work safely. Aluminum alloys have been in use for the last 100 years, and especially since the 1930s in the aviation industry.


176

Avio industrija u širokoj upotrebi koristi aluminijske legure 2xxx1 i 7xxx. Ostale aluminijske legure također su zatupljene u širokoj upotrebi, ne samo u avionskoj nego i u ostalim industrijskim granama. U autoindustriji sve veći je interes za korištenje legura aluminija (Al) 6xxx, koje predstavljaju legure aliminija sa silicijem i magnezijem. Ove legure u širokoj su upotrebi za izradu karoserije i branika na automobilima. Razlog ovog predstavljaju skoro idealne mehaničke osobine ove grupe legura. 6xxx grupa Al legura u upotrebi je zbog njihovih mehaničkih osobina: lahkoće, dobre žilavosti, oblikovanja, zavarljivosti, otpornosti na koroziju, i niske cijene koštanja. Ispitivanje AL legura na žilavost široko je prisutno, te se nastoji koristiti gdje god to uvjeti dozvoljavaju. Pored osnovnog metala legure, ispitivanje žilavosti zastupljeno je i kod zavarenog spoja, pri čemu je sama tehnologija ispitivanja složenija. Korištenje složenijih ispitivanja nužno je uključiti jer zavareni spoj, zbog svoje heterogenosti, zahtjeva posebna ispitivanja osnovnog metala (OM), zone uticaja toplote, (ZUT) te metala šava (MŠ) [2]. Ispitivanje žilavosti i zamora materijala temelji se na procedurama koje su definisane standardima prvenstveno American Society for Testing and Materials (ASTM) i British Standards Institution (BSI) koji u potpunosti definišu sve procedure ispitivanja kako osnovnog materijala tako i zavarenih spojeva [3]. Modul elastičnosti , napon tečenja , zatezna čvrstoća te ukupno izduženje, za leguru 6061-T61 dati su u tabeli 1 [4].

Aluminum alloys 2xxx1 and 7xxx are widely used in the aviation industry. Other aluminum alloys are also represented in wide use, not only in aviation but also in other industries. The automotive industry is showing a growing interest in the use of aluminum alloy 6xxx, which is representing aluminum alloys with Silicon and Magnesium. This alloy is widely used for the bodywork and bumpers of cars. The reason for this is almost ideal mechanical properties of this group of alloys. 6xxx group of Al alloys is widely used because of its mechanical properties: lightness, good toughness, design, weldability, corrosion resistance, and low cost. Testing of Al alloy toughness is widely present, with the tendency of being used wherever conditions allow. In addition to the base metal alloy, toughness testing is also present in the welded joint, where the testing technology is more complex. Use of complex testing must be enabled as welded joint, because of its heterogeneity, requires special testing of base metal (BM), heat affected zone (HAZ) and weld metal (WM) [2]. Testing of toughness and fatigue is based on the procedures defined by the standards, primarily American Society for Testing and Materials (ASTM) and British Standards Institution (BSI) which fully define all testing procedures of the base material and welded joints [3]. Modulus of elasticity , yield strength , tensile strength and total elongation for aluminum alloy 6061-T61 are given in Table 1 [4].

Tabela 1. Mehaničke osobine za leguru 6061-T61[18] Table 1 Mechanical properties for alloy 6061- T61[18] 2. STANDARDI ZA ANALIZU I ISPITIVANJE ZAMORA I ŽILAVOSTI AL LEGURA Sva ispitivanja kako Al legura tako i drugih metala definisana su nacionalnim standardima.

1 Oznake xxx Al legure predstavljaju prostor za unos osnovni konstutivnih elemenata legure. Npr. 6xxx predstavlja leguru aluminija čiji su osnovni konstituenti Magnezij i Silicij.

2. STANDARDS FOR THE ANALYSIS AND TESTING OF FATIGUE AND TOUGHNESS OF AL ALLOYS The testing of Al alloys and other metals is defined by national standards.

1The xxx Al alloy mark is the space for entering the constituent elements of the alloy. Eg. 6xxx represents aluminum alloy whose basic constituents are Magnesium and Silicon.


177

Prve prijedloge standarda za određivanje, pored ostalog, žilavosti loma objavili su Američko društvo za ispitivanje i materijale (American Society for Testing and Materials – ASTM) – ASTM E399-70T, i Britanska institucija za standarde (British Standard Institution – BSI). Standardi su objavljeni po naslovom "Standardni postupak ispitivanja žilavosti loma pri ravnoj deformaciji metalnih materijala" [5], odnosno BS 5447 [6]. Nešto kasnije je BSI objavio prijedlog standarda za određivanje otvaranja prsline DD 19 (Standard Test Method for Crack Opening Displacement), usvojen kao BS 5762 [7]. Poslije usvajanja ovih standarda, predložen je veliki broj standarda za ispitivanje epruveta sa prslinama. Među njima su najviše korišteni: • ASTM E 813 – 89: (Standardni postupak

ispitivanja JIc)[8]. • ASTM E 1152 – 87: (Standardni postupak

ispitivanja za određivanje J-R krive)[9]. • ASTM E 1737 – 96: (Standardni postupak

ispitivanja za određivanje žilavosti loma pomoću J integrala). Ovaj standard je objedinio dva standarda (E 813 i E 1152), koji su u najvećem dijelu podudarni, a na osnovu iskustva iz njihove primjene u prošireno područje primjene J integrala u karakterizaciji materijala [10].

• ASTM E 1820 – 99a: (Standardni postupak ispitivanja za mjerenje žilavosti loma). Ovaj standard je objedinio standarde E 399, E 1290 i E 1737 [11].

Sličan pristup je usvojen i u Britanskim standardima, pa je u BS 7448 "Fracture mechanics toughness tests" [12] definisano ispitivanje žilavosti loma, odnosno u njegovom prvom dijelu "Methods for determination of KIc, critical CTOD and critical J values of metallic materials" objedinjeni su postupci za određivanje KIc, kritičnog CTOD i kritične J vrijed-nosti metalnih materijala. U drugom dijelu BS 7448 "Methods for determination of KIc, critical CTOD and critical J values of welds in metallic materials" [13], koji je objavljen 1997. godine, propisuje se postupak ispitivanja pomoću parametara mehanike loma, zavarenih spojeva. U razradi su treći dio za određivanje dinamičke žilavosti loma i četvrti dio za određivanje krivih otpornosti.

The first proposals of standards for determining fracture toughness were published by the American Society for Testing and Materials (ASTM) – ASTM E399-70T, and the British Standards Institution (BSI). The given proposals were accepted under the title ‘’Standard Test Method for Plane-Strain Fracture Toughness of Metallic Materials as ASTM E 399-86 [5], or BS 5447 [6]. Somewhat later, the BSI published a draft standard for determining crack opening DD 19 (Standard Test Method for Crack Opening Displacement), adopted as BS 5762 [7]. After the adoption of these standards, a number of standards were proposed for testing specimens with cracks. Among them, the most common are: • ASTM E 813 – 89: Standard Test Method

for JIc, a Measure of Fracture Toughness[8]. • ASTM E 1152 – 87: Standard Test Method

for Determining J-R Curve [9]. • ASTM E 1737 – 96: Standard Test Method

for J Integral Characterization of Fracture Toughness. This standard has integrated two standards (E 813 and E 1152), which are matching for the most part, based on the experience of their application in the extended application area of J integral in the characterization of materials [10]

• ASTM E 1820 – 99a: Standard Test Method for Measurement of Fracture Toughness. This standard integrated standards E 399, E 1290 and E 1737 [11].

Similar approach was adopted in the British standards, so BS 7448 ‘’Fracture mechanics toughness tests’’ [12] defines testing of fracture toughness. Its first part ‘’Methods for determination of KIc, critical CTOD and critical J values of metallic materials’’ integrates procedures for the determination of KIc, the critical CTOD and critical J-value of metallic materials. The second part of BS 7448 ‘’Methods for determination of KIc, critical CTOD and critical J values of welds in metallic materials’’ [13], published in 1997, determines the procedure for testing the fracture mechanics of welded joints. The third part for the determination of dynamic fracture toughness and the fourth part for the determination of resistance curves are being developed.


178

3. ISPITIVANJA ALUMINIJSKIH 6XXX LEGURA Često je u primjeni legiranje osnovnog materijala da bi se dobile one mehaničke osobine koje su potebne da se poveća napon tečenja materijala, žilavost materijala, električne i toplotne osobine, povećana otpornost od korozije i dr. Legiranje materijala, s druge strane, zahtjeva posebna ispitivanja dinamičkih osobina poput razvoja prsline i određivanja dinamičke čvrstoće materijala. Santana i dr. ispitivali su dinamičku otpornost na lom aluminijskih legura 6061-T6 sa prslinama i AlSi 4140T čeličnih epruveta pod visoko frekventnim i nisko frekventnim zamorimim opterećenjima. U radu su pokazali da se plastičnost aluminijske legure povećava kada se povećava nivo zamornog oštećenja [14]. Ding i drugi ispitivali zamorno ponašanje legure AA6061 kao kompozitnog materijala [15]. 4. DINAMIČKA ČVRSTOĆA ALUMINIJSKIH LEGURA Zamorna prslina i lom način su definisanja zamora metala. Kako se u ovom slučaju radi o legurama aluminija, vrlo je važno da se ista analizira na ispitivanja visokocikličnog zamora. Dinamička čvrstoća legure pri promjenjivom opterećenju igra značajnu ulogu u ocjeni stabilnosti konstrukcije. Iskustva su pokazala da se prsline i oštećenja javljaju pri velikom broju promjena opterećenja, dok su naponska opterećenja niža od napona tečenja. Od posebne važnosti za svaku konstrukciju jeste da se materijal prethodno podvrgne ispitivanjima na visokociklični zamor. Za opterećenja niža od napona tečenja, koji je karakteristika za visokociklični zamor, najčešće se ispitivanje izvodi u krutom režimu, pri zadanoj amplitudi opterećenja MPa . Prakticira se, da ciklus opterećenja simulira uvjete rada konstrukcije sa uproštenim oblicima ciklusa opterećenja. Ciklični zamor predstavlja se u formi krive σ −N, pri čemu σ predstavlja naprezanje a N broj ciklusa. Kriva − prikazuje rezultate ispitivanja pri čemu se na testnoj mašini na ordinati nanosio normalni sinusoidalni napon, dok se na apcisi nanosio odgovarajući broj ciklusa. Dijagram pokazuje da u koliko se materijal optereti naponom ispod graničnog napona, za odgovarajući broj ciklusa, neće doći do oštećenja, bez obzira koliko puta on bio podrvgnut ovom opterećenju.

3. PRECEDING TESTING OF ALUMINUM 6XXX ALLOYS Alloying of the base material is frequently applied in order to obtain those mechanical properties which are required for the increased yield strength of materials, toughness, electrical and thermal properties, increased corrosion resistance, etc. On the other hand, material alloying require special testing of dynamic properties such as crack growth and dynamic toughness. Santana et al examined the dynamic resistance of aluminum alloy 6061-T6 with cracks and AlSi 4140T steel tubes under high frequency and low frequency fatigue loads. Analysis showed that the plasticity of aluminum alloy is increased when increasing the damage level [14]. Ding et al examined the fatigue behavior of alloy AA6061 as a composite material[15]. 4. FATIGUE STRENGTH OF ALUMINUM ALLOYS Fatigue crack and fracture are the ways of defining the metal fatigue. As, in this case, it is an aluminum alloy, it is very important for it to be analyzed at high cyclic fatigue tests. Fatigue strength of the alloy at variable load represents an important role in assessing the stability of the structure. Experience has shown that the cracks and defects occur in a large number of load changes, whereas the tensile stress is lower than the yield stress. Of particular importance for each structure is that materials undergo primary testing on the high-cycle fatigue. For loads lower than the yield stress, which is characteristic for high-cyclic fatigue, the most common test is performed in rigid mode, at a given stress amplitudeσa [MPa]. It is common that load cycle simulates the working conditions of construction with simplified forms of load cycles. Cyclic fatigue is represented asσ – Ncurve, wherein σ represents stress and N number of cycles. Curve σ – N shows the results of testing in which the normal sinusoidal load was applied on the testing machine where an appropriate number of cycles was applied on the x-axis. The diagram shows that, if the material is loaded below the limit for the appropriate number of cycles, there will be no defect, regardless of how many times it was submitted to this load.


179

Vijek zamora predstavlja broj naponskih ciklusa određenog oblika, koje epuveta može prihvati, a da ne dođe do loma, odnosno broj ciklusa opterećenja koje material može da izdrži, a da ne dođe do njegovog loma. Dinamička čvrstoća sa brojem ciklusa za aluminijske legure 6xxx prikazana je na slici 1. Sa slike se može uočiti da na smanjenje dinamičke čvrstoće uzrokuje povećanje broja ciklusa [1]. Na slici se također može uočiti da uspoređivanje dinamičke čvrstoće aluminijske legure sa različitima brojem ciklusa sa ili bez toplotne obrade. Toplotna obrada urađena je na temparaturama 420, 460, 500 oC i držanje na tim temperaturama 1 sat. Može se uočiti da se broj ciklusa povećava za legure koje su termički obrađene i to za 44%, 55% i 64% u odnosu na neobrađenu leguru respektivno[16].

Fatigue life represents the number of load cycles of a certain shape that tube can accept without cracking, or the number of cycles that the material can accept to avoid its fracture. Fatigue strength with the number of cycles for aluminum alloy is shown in Figure 1. The Figure 1 indicates that the reduction in fatigue strength causes an increase in the number of cycles [1]. Figure 1 also depicts the comparison of fatigue strength of aluminum alloy with a different number of cycles with and without heat treatment. Heat treatment was conducted at temperatures of 420, 460, and 500 �C for 1 hour of toughening. We can see that the number of cycles increase for the alloys that were heat treated to 44%, 55% and 64% compared to non-treated alloys, respectively [16].

Slika 1. Zamorna čvrstoća sa brojem cikličnih opterećenja za grupu termički obrađenih aluminijskih 6xxx legura [16] Figure 1. Fatigue strength with number of cyclic loads for the group of thermally treated Aluminum 6xxx alloys [16]

5. RAST ZAMORNE PRSLINE KOD ALUMINIJSKIH LEGURA Teorijskim analizama nije moguće u potpunosti objasniti fenomen ponašanja materijala kod promjenjivog opterećenja, pa se kombinacijom eksperimentalnog i teorijskog pristupa o ovom fenomenu mogu izvući određeni zaključci i dobiti kvalitetni rezultati [17]. Pogodnom analizom i ispitivanjem moguće je jasno odrediti prelaznu fazu zamorne prsline, u kojoj ona nastaje, i u kojoj zamorna prslina raste do kritične veličine, odnosno do loma materijala.

5. FATIGUE CRACK GROWTH IN ALUMINUM ALLOYS Theoretical analysis cannot fully explain the phenomenon of behavior of materials with variable loads, whereas the combination of experimental and theoretical approach of this phenomenon can help make some conclusions and obtain quality results [17]. Suitable analysis and testing can clearly define transitional phase of fatigue crack, in which it occurs, and the second phase in which the crack grows to a critical size, or to material fracture.


180

Pri svakom lomu nedvosmisleno se može izračunati broj ciklusa potrebnih da zamorna prslina nastane i broj u kojima se ona razvija do kritične veličine . Shodno tome, ukupan broj ciklusa može se predstaviti sljedećim izrazom:

= + . (1) Parisova jednačina u stanju je da odredi razliku između nastajanja i rasta zamorne prsline što je od velikog značaja. Standard ASTM E647 [18] definiše na koji način se može izmjeriti rast zamorne prsline, koja je prije toga prošla fazu nastajanja. Važna činjenica se ovdje može primijetiti, a to je da bez obzira što je u konstrukciji nastala faza stvaranja prsline, konstrukcija se još uvijek može eksploatirati sve dok veličina prsline ne pređe kritičnu veličinu. Ukoliko se poznaje brzina rasta zamorne prsline, konstrukciju je moguće eksploatirati potpuno bezbjedno sve do perioda u kojem se očekuje da veličina zamorne prsline prelazi kritičnu vrijednost. Otpornost materijala i stabilnost rasta prsline pri cikličkom opterećenju općenito je data kroz krive − , odnosno − , pri čemu – predstavlja ciklično nprezanje, - broj ciklusa, dužina prsline. Pored ovih dijagrama vrlo važan dijagram predstavlja i brzina rasta zamorne prsline / u odnosu na veličinu otvaranja prsline CTOD, KIc koeficijent intenziteta napona. Općeniti dijagram između rasta zamorne prsline i Δ za većinu aluminijskih legura 6xxx prikazuje slika 2. Na slici 2 su prikazani dijagrami za aluminijsku leguru 6061-T61 za različite vrste procesa obrade i zamorne prsline. Na slici 2 brzina rasta zamorne prsline računata je uz prisustvo niske vrijednosti zaostalih naprezanja R=0.1. 6. ZAKLJUČAK U rada su prikazani neki od osnovnih značajki aluminijskih legura oznake 6xxx, koje široku upotrebu imaju u auto industriji. U radu su prezentiranih i osnovni standardi za ispitivanje parametara mehanike loma, dinamičke čvrstoće i drugim važnih osobina legura. Poseban aspekt stavljen je na britanske i američke standarde ispitivanja koji su se prvi pojavili i definisali ovu problematiku.

During each fracture, the number of cycles required for fatigue crack to occur Ni and number in which it develops to a critical size Np can clearly be calculated. Consequently, the total number of cycles can be represented by the following equation.

= + . (1) Paris equation is able to determine the difference between initiation and crack growth rate which is of great importance. Standard ASTM E647 [18] defines how one can measure the fatigue crack growth, which has previously passed the initiation phase. An important fact to be noted here is that regardless of the fact that crack initiation phase has occurred in the construction, the construction can still be exploited until the crack size does not exceed the critical size. If the fatigue crack growth is known, the construction can be exploited completely safe until the period in which it is expected that the size of the fatigue crack will exceed the critical value. Strength of material and stability of crack growth under cyclic loading is generally given through the curve σ – N or a – N, where σ – represents a cyclic load, N – number of cycles, a – crack length. In addition to these diagrams, one very important diagram presents the fatigue crack growth rate da/dN in relation to the size of the crack opening displacement CTOD, KIc stress intensity factor. The general diagram of fatigue crack growth and ΔK for most aluminum alloys 6xxx is shown in Figure 2. Figure 2 shows diagrams of aluminum alloy 6061-T61 for different machining process and values of the initial fatigue crack. In Figure 2, fatigue crack growth rate is calculated with the presence of low levels of residual stresses R = 0.1. 6. CONCLUSION The paper presents some of the basic properties of aluminium 6xxx alloys, which are widely used in the automotive industry. The basic standards for testing the parameters of fracture mechanics, dynamic strength and other important properties of alloys are presented in this paper. A special aspect was put on the British and US standards of testing which are first appeared and defined this area.


181

Slika 2. Rast zamorne prsline za AL6061-T61 pri različitim procesima obrade uz zaostalo naprezanje[17] Figure 2. Fatigue crack growth for alloy AL6061-T61 for various machining process [17]

Za aluminijsku leguru 6061 prikazane su osnovne mehaničke osobine koje predstavljaju ulazne parametre za ispitivanje dinamičke čvrstoće, vijeka trajanja legure u odnosu na dinamička ciklična naprezanja, te rast zamore prisilne. Ispitivanja aluminijskih legura pokazuju da se plastičnost povećava sa povećanjem veličine zamornog oštećenja.

For aluminium alloy 6061 basic mechanical properties are presented. Those values were input parameters for testing the dynamic strength, the life of the alloy in relation to dynamic cyclic stresses, and the fatigue crack growth. Aluminium alloy tests show that plasticity increases with increasing damage level.

7. LITERATURA - REFERENCES [1] Imam M.F.I.A; Rahman, M. S.; KHAN

M.Z.H.; Influence of Heat Treatment on Fatigue and Fracture Behavior of Aluminium Alloy, Journal of Engineering Science and Technology Vol. 10, No. 6 (2015) 730 – 742

[2] Wang, C.; and Chang, Y. (1996). Effect of post-weld treatment on the fatigue crack growth rate of electron beam-welded AISI 4130 steel. Metallurgical and Material Transactions, 27(10), 3162-3169.

[3] Khan, S.; Wilde, F.; Beckmann, F.; and Mosler, J. (2012). Low cycle fatigue damage mechanism of the lightweight alloy

Al2024. International Journal of Fatigue, 38, 92-99.

[4] ASTM E8 / E8M-08, Standard Test Methods for Tension Testing of Metallic Materials, ASTM International, West Conshohocken,PA,2008, www.astm.org

[5] ASTM E399-87, Standard Test Methodfor Plane-Strain Fracture Toughness of-Metallic Materials, Annual Book of ASTM Standards, Vol. 04.0 1. p. 522. 1986.

[6] BS 5447:1977, Method of Test of Plain Strain Fracture Toughness KIc of metallic materials, BSI, 1972.

[7] BS 5762, Method for determination of critical CTOD values of metallic materials, BSI, 1991.


182

[8] ASTM E813-89, Standard Test Method for JIc, A Measure of Fracture Toughness, Annual Book of ASTM Standards 1986, Vol. 04.01. p. 651.

[9] ASTM E 1152-91, Standard Test Method for Deterrmining J-R Curve, Annual Book of ASTM Standards 1986, Vol. 04.01. p. 724.

[10] ASTM E 1737-96, Standard Test Method for J Integral Characterization of Fracture Toughness, Annual Book of ASTM Standards 1996, Vol. 04.01.

[11] ASTM E 1820-99a, Standard Test Method for Measurement of Fracture Toughness, Annual Book of ASTM Standards 1999, Vol. 04.01.

[12] BS 7448., Fracture mechanics toughness tests. Part 1. Method for determination of KIc critical CTOD and critical J values of metallic materials, BSI, 1991.

[13] BS 7448, Fracture mechanics toughness tests. Part 2. Method for determination of KIc, critical CTOD and critical J values of welds in metallic materials, BSI, 1997.

[14] Snchez-Santana, U.; Rubio-Gonzlez, C.; Mesmacque, G.; and Amrouche, A. (2009). Effect of fatigue damage on the dynamic tensile behavior of 6061-T6 aluminum alloy

and AISI 4140T steel, International Journal of Fatigue, 31(11-12), 1928-1937.

[15] Ding, H.Z.; Biermann, H.; and Hartmann, O. (2002). A low cycle fatigue model of a short-fibre reinforced 6061 aluminum alloy metal matrix composite, Composites Science and Technology, 62(16), 2189-2199.

[16] Anastasios G. G.; Brendan F. C.; Diana A. L.; Effects of microstructure on the fatigue crack growth behavior of light metals and design considerations, Revista Matéria, v. 15, n. 2, pp. 319-329, 2010.

[17] Paris P. C., and Erdogan F., A Critical Analysis of Crack Propagation Laws, Trans. ASME, Journal Basic Eng., Vol. 85, No. 4, p. 528.

[18] ASTM E647-13a, Standard Test Method for Measurement of Fatigue Crack Growth Rates, ASTM International, West Conshohocken, PA, 2013, www.astm.org

Coresponding author: Bahrudin Hrnjica University of Bihac, Faculty of Technical Engineering Email: [email protected] Phone: +387 37 226 273

Mašinstvo 4(14), 183 – 192, (2017) A. Kahriman, et all: THE DISCRICT HEATING SYSTEM…

183

SISTEM DALJINSKOG GRIJANJA U KAKNJU

THE DISTRICT HEATING SYSTEM IN THE CITY OF KAKANJ

Almir Kahriman1, Nedim Hodžić2, Elma Ekinović2 1JP ,,Grijanje” d.o.o. Kakanj, Kakanj 2University of Zenica, Faculty of Mechanical Engineering, Zenica Ključne riječi: sistem, daljinsko grijanje, Kakanj, toplotne podstanice, izmjenjivači toplote Keywords: system, district heating, Kakanj, heat substations, heat exchangers Paper received: 04.10.2017. Paper accepted: 26.12.2017.

Stručni rad REZIME Zagrijavanje stambenih i poslovnih prostora u urbanim područjima tokom zime najčešće se ostvaruje korištenjem toplotne energije koja se distribuira putem centralnog ili gradskog grijanja. Kao osnovni radni medij za generisanje toplotne energije najviše se koriste voda, para i plin. Za zagrijavanje grada Kaknja i njegovih okolnih naselja, toplotna energija se proizvodi u Termoelektrani „Kakanj“i dalje distribuira do krajnjih potrošača koji su na relativno velikim udaljenostima od izvora toplotne energije. U ovom radu opisan je sistem daljinskog grijanja u gradu Kaknju i proces distribucije toplotne energije koju vrši JP „Grijanje“ d.o.o. Kakanj.

Professional paper

SUMMARY The heating of residential and commercial premises in urban areas during winter periods is mostly performed by use of the heat energy which is distributed through central or city heating systems. Water, steam and gas are used as the basic working media in these heating systems. The thermal energy that is used in the city of Kakanj and its surrounding settlements is produced in the Thermal Power Plant Kakanj and then delivered to the final consumers, which are usually located at relatively large distances from the heat source. This paper describes the district heating system in Kakanj and the process of heat energy distribution carried out by JP „Grijanje“ d.o.o. Kakanj.

1. UVOD Sistem zagrijavanja grada Kaknja je „zatvoreni“ sistem u kojem stalno cirkuliše voda zahvaljujući pumpnom postrojenju. Općenito, voda se najčešće koristi kao radni medij u sistemima daljinskog grijanja, jer je jedan od najboljih nosilaca toplote. Sistem daljinskog grijanja (SDG) je pušten u pogon 1986. godine i njegova izgradnja je izvršena u nekoliko faza, a to su [1]:

1. INTRODUCTION The heating system in the city of Kakanj is a "closed" system in which water constantly circulates thanks to the pumping plant. Generally, water is primarily used as a working medium in district heating systems, because it is one of the best heat carriers. The district heating system (DHS) was put into operation in 1986 and its construction was carried out in several stages, which are [1]:

Slika 1. JP „Grijanje“ d.o.o. Kakanj

Figure 1. JP „Grijanje“ d.o.o. Kakanj


184

Faza I (1985., 1986., 1987.) – izgradnja magistralnog vrelovoda do grada Kaknja; Faza II (1986., 1987., 1988.) – izgradnja toplotnih podstanica i toplovodne mreže na nivou grada Kaknja; Faza III (2008.) – izgradnja toplovodne mreže u prigradskom naselju Doboj; Faza IV (2015.) – izgradnja toplovodne mreže u MZ Kakanj II; Faza V – rekonstrukcija toplifikacionog sistema po potrebi i dalje širenje mreže. Sistem daljinskog grijanja (SDG) sastoji se od: - toplotne stanice (TS) smještene u

Termoelektrani „Kakanj“, a koja služi za pripremu vrele vode (25bar, 150°C);

- vrelovoda koji je prvenstveno namijenjen za transport vrele vode;

- toplotnih podstanica (TP) koje služe za dobijanje tople vode (10bar, 65°C) i

- toplovoda za transport tople vode od toplotnih podstanica do krajnjih potrošača.

Opisani sistem grijanja karakteriše velika udaljenost (dostiže i do 10 kilometara) od izvora toplotne energije (TS) do krajnjih potrošača, a isto tako i velike toplotne podstanice (TP) zbog potrebnog velikog kapaciteta toplotne energije (48 MW). Za sistem daljinskog grijanja (SDG) u Kaknju može se sa sigurnošću tvrditi da je trenutni odnos utrošene električne energije prema proizvodnji toplotne energije 1:4, respektivno. Obračun usluga zagrijavanja stambenih i poslovnih prostora vrši se na osnovu fiksnog dijela koji zavisi od površine zagrijavanog prostora u m2 i varijabilnog dijela koji zavisi od vrijednosti očitane potrošnje toplotne energije na mjerilu (kalorimetru) u MWh. 2. OSNOVNE KARAKTERISTIKE SDG U KAKNJU Način distribucije toplotne energije pomoću sistema daljinskog grijanja (SDG) je prikazan na slici 2. Osnovni elementi takvog sistema zagrijavanja su: toplotna stanica (TS), vrelovod, toplotne podstanice (TP), toplovod i krajnji korisnici. 2.1. Toplotna stanica (TS) Toplotna stanica (TS) smještena u Termoelektrani „Kakanj“ između blokova 4 i 5 na koti od 390 metara nadmorske visine.

Phase I (1985, 1986, 1987) - construction of the main hot water supply pipeline to Kakanj; Phase II (1986, 1987, 1988) - construction of thermal substations and heating network at the level of the city Kakanj; Phase III (2008) - construction of warm water supply network in the suburb Doboj; Phase IV (2015) - construction of the heating network in MZ Kakanj II; Phase V - reconstruction of the heating system by need and further network expansion. The district heating system (DHS) consists of: - heat station (HS) located in Thermal Power Plant Kakanj, that is used for preparation of hot water (25bar, 150°C); - hot water supply pipeline, which is primarily intended for hot water transport; - heat substations (HSS) that serve to generating warm water (10bar, 65°C) and - pipeline for warm water transporting from heat substations to final consumers. The described heating system is characterized by a large distance (it reaches up to 10 kilometers) from the heat source (HS) to the end consumers, as well as large heat substations (HSS) due to high heat capacity requirements (48 MW). For the district heating system (DHS) it can be pointed out that the present ratio of the consumed electricity to the heat production is 1: 4, respectively. The calculation of heating costs for residental and office spaces is based on the fixed part which depends on the heated area in m2 and variable part which depends on the apparent consumption of heat energy on a scale (calorimeter) in MWh. 2. BASIC CHARACTERISTICS OF DHS IN KAKANJ The heat distribution by district heating system (DHS) in Kakanj is graphicallly presented in Figure 2 . The major components of a district heating system are: heat station (HS), hot water supply pipe, heat substations (HSS), warm water supply pipe and final users. 2.1. Heat station (HS) The heat station (HS) located at the Thermal Power Plant „Kakanj“ between blocks 4 and 5 at 390 meters above sea level.


185

Ona predstavlja postrojenje koje služi za pripremu vrele vode (25bar, 150°C) korištenjem zagrijane pare koja se uzima sa niskotlačnih i srednjetlačnih dijelova turbine. Da bi se postigli neophodni parametri vrele vode, koriste se specijalni izmjenjivači toplote niskog i visokog pritiska. Za zagrijavanje grada Kaknja koristi se snaga od otprilike 48 MW koja se uzima sa turbinskih postrojenja blokova 5, 6 i 7, [2]. Prije punjenja sistema daljinskog grijanja, voda se mora prvo hemijski pripremiti, odnosno pretvoriti u demineralizovanu (tzv. „demi“) vodu.

The heat station is used for preparation of hot water (25bar, 150°C) using the steam that is taken from the low pressure and medium pressure parts of the turbine. In order to achieve the necessary parameters of hot water, special heat exchangers of low and high pressure are used. The total power of approximately 48 MW from turbine units of blocks 5, 6 and 7 is used for heating of Kakanj, [2]. Before filling the district heating system the water must be chemically prepared, i.e. be converted to the demineralized (so-called „demi“) water.

Slika 2. Šematski prikaz sistema daljinskog grijanja (SDG)

Figure 2. The district heating system (DHS) scheme Na slici 3. je prikazan T-s dijagram proizvodnje pare pomoću koje se u toplotnoj stanici pomoću izmjenjivača toplote dobija vrela voda. Na dijagramu su prikazani sljedeći procesi: 1-2 izentropski proces povećanja pritiska vode; 2-3 izobarni proces pregrijavanja pare; 3-4 izentropski proces ekspanzije pare i, 4-1 izobarni proces kondenzacije pare. Ukoliko ovakvo postrojenje poslije kotla ne sadrži izmjenjivač toplote onda se tačke 3 i 4 poistovjetuju na T-s dijagramu sa tačkama 3`i 4`. 2.2. Vrelovod Distribucija vrele vode vrši se preko vrelovodne mreže koja se sastoji od cjevovoda koji je djelimično izgrađen nadzemno (5,7 km), a djelimično podzemno (6,2 km) u armirano-betonskom kanalu. Vrelovod se sastoji od potisnog i povratnog voda temperaturnih parametara u iznosu 150/75°C. Zbog dotrajalosti cjevovoda, navedene vrijednosti temperature se ne mogu se postići, tako da maksimalna temperatura na potisnom dijelu vrelovoda iznosi oko 120°C. Također, vrelovod sadrži U-kompenzatore koji se postavljaju na određenom, proračunom dobijenom, razmaku i omogućavaju termičko istezanje cjevovoda u dozvoljenim granicama [3].

Figure 3. shows the T-s vapor production diagram by which hot water is obtained in the heat station by means of a heat exchanger. The diagram shows the following processes: 1-2 isentropic process of increasing pressure water; 2-3 isobaric process of overheating steam; 3-4 isentropic steam expansion process and, 4-1 isobaric steam condensation process. If the that plant does not contain a heat exchanger after the boiler then points 3 and 4 are identified on the T-diagram with points 3` and 4`. 2.2. Hot water supply pipeline The distribution of hot water is carried out through the hot water network, which consists of a pipeline that is partly installed over ground (5.7 km) and partly underground (6.2 km) in RC (reinforced-concrete) channels. The hot water network consists of feed and return lines with 150/75°C temperature parameters. Due to pipeline deterioration, these values of temperatures can not be achieved, so the maximum temperature in the hot water feed pressure line is approx. 120 °C. The hot water pipeline contains also U-compensators that are set at a calculated distance and allow for thermal expansion of the pipeline within the permissible limits [3].


186

Slika 3. T-s dijagram za paru

Figure 3. T-s diagram for the steam U zadnje vrijeme, vrelovodna mreža se najčešće izgrađuje od predizoliranih cijevi koje se postavljaju u kanale sa sekcionim ventilima koji omogućavaju lako pražnjenje sistema u najnižim tačkama po pojedinačnim dionicama sistema. Odzračivanje sistema se vrši pomoću odzračnih ventila smještenih u najvišoj tački sistema. PEHD-obložena cijev, slika 4, i cijev za radni medij međusobno su čvrsto povezane putem PUR-tvrde pjene, te čine kompaktan sistem. Time se predizolovana cijev kao i tehnika polaganja znatno razlikuju od konvencionalnih postupaka [3].

Recently, the hot water network is most often constructed from pre-insulated pipes that are placed in the channels with sectional valves that allow easy emptying of the system at the lowest points per individual system parts. Ventilation of the system is carried out by means of vent valves located at the highest point of the system. The PEHD-coated tube, Fig. 4, and the working fluid tube are interconnected with each other by PUR-hard foam and form a compact system. Thus, the pre-insulated tube as well as the laying technique differs significantly from conventional methods, [3].

Slika 4. Poprečni presjek PEHD obložene cijevi Figure 4. Section view of PEHD coated tube

2.3. Toplotne podstanice (TP) Toplotne podstanice predstavljaju postrojenja u kojima se pomoću izmjenjivača toplote vrši dobijanje tople vode (10 bar, 65°C). Pored navedenih izmjenjivača toplote, toplotne podstanice sadrže i manometar i termometar na potisnoj i povratnoj strani, ekspanzione posude, sigurnosne ventile, cirkulacione i diktir-pumpe, mjerila toplotne energije (kalorimetra) i druge dijelove koji su neophodni.

2.3. Heat substations (HSS) Heat substations are plants where hot water (10bar, 65°C) is generated by use of the heat exchangers. Except the heat exchangers, there are manometer and thermometer on the pressure and return side inside the heat substation, expansion vessels, safety valves, circulation and dictating pumps, heat energy meters (calorimeters) and other necessary parts.


187

Toplotne podstanice se analogno mogu posmatrati kao transformatori, jer se sastoje od primarne strane (vrelovodne mreže) i sekundarne strane (toplovodne mreže). S obzirom na izvedbu izmjenjivača toplote, razlikuju se: - kompaktne toplotne podstanice sa

pločastim izmjenjivačima toplote, slika 5, i - toplotne podstanice sa cijevnim izmjenjiva-

čima toplote, slika 6. Osnovna razlika između navedenih podstanica jeste u tome što kompaktne toplotne podstanice zauzimaju manji prostor i mogu se lakše automatski nadzirati. Međutim, kompaktne toplotne podstanice se ne mogu nikako redovno čistiti i održavati, izuzev ako se ne radi o rastavljivim pločastim izmjenjivačima toplote. Ako se neka od cijevi začepi ili ošteti kod cijevnih izmjenjivača, potrebno je samo blindirati začepljenu ili oštećenu cijev. Na taj način, cijevni izmjenjivač toplote nije potrebno mijenjati u potpunosti.

Heat substations are analogue to transformers, because they consist of a primary side (hot water network) and a secondary side (warm water network). With regard to the heat exchanger's performance, there are:

- compact heat substations with plate heat exchangers, figure 5, and

- heat substations with tubular heat exchangers, figure 6.

The basic difference between the mentioned substations is that compact heat substations occupy smaller space and are easier to be controlled automatically. However, compact heat substations can not be cleaned and maintained regularly, except in cases with removable plate heat exchangers. If one of the tubes is clogged or damaged on the pipe exchanger, it is necessary to only wrap the jammed or damaged pipe. In this way, the replacement of a complete heat exchanger is avoided.

Slika 5. Pločasti izmjenjivač toplote Slika 6. Cijevni izmjenjivač toplote Figure 5. The plate heat exchanger Figure 6. The tubular heat exchanger

2.4. Toplovod Toplovodna mreža kao i vrelovodna, sastoji se od podzemnih predizoliranih cijevi koje služe za distribuciju tople vode od toplotnih podstanica do krajnjih korisnika sistema daljinskog grijanja. Temperaturni režim na potisnoj i povratnoj strani toplovoda iznosi oko 65/55°C, respektivno. Za razliku od vrelovoda u kojem se koristi mnogo veći promjer cijevi zbog lakšeg savladavanja otpora pri transportu vrele vode, kod toplovoda se koriste manji promjeri cijevi zbog boljeg zadržavanja toplote unutar cijevi.

2.4. Pipeline of warm water Warm water network as well as hot water network, consists of underground pre-insulated pipes that serve to distribute warm water from heat substations to the end users of district heating system. The temperature regime on the pressure and return side of the heating line is approx. 65/55°C, respectively. Unlike the hot water network that uses pipes with relativelly large diameters to decrease the resistance of hot water transportation, pipes with smaller diameters are used for warm water network to ensure better heat retention inside the pipe.


188

Zbog velikog broja korisnika sistema daljinskog grijanja i stalnog širenja toplovodne mreže, može se reći da je toplovodna mreža mnogo veća od vrelovodne mreže. Važno je istaći da se pražnjenje i odzračivanje toplovoda vrši na isti način kao i kod vrelovoda, tj. pomoću sekcionih, odnosno odzračnih ventila. Za lakše otkrivanje kvarova na sistemu, tj. za detekciju puknuća na vrelovodnoj i toplovodnoj mreži, koriste se dvije žice, bakarna i kalajna, slika 3. One se postavljaju na pojedinim mjestima unutar izolacije, kako bi se omogućila provjera fizičke ispravnosti cjevovoda. Detekcija puknuća se vrši na osnovu promjene otpora u žicama kada dođu u dodir sa vodom. Tada specijalni uređaj za detekciju, spojen sa navedenim žicama, registrira signal koji ukazuje na to da je došlo do puknuća na cjevovodu.

Due to the large number of users of the district heating system and constant spread of the hot water network, it can be said that the warm water network is much larger than the hot water network. It is important to note that the discharge and venting of warm water network is done in the same way as for hot water network, i.e. using sectional or venting valves. For easier detection of failures of system, i.e. for breakage detection on the hot and warm water network, two wires of copper and tin are used, Figure 3. They are placed in individual locations within the insulation to allow the physical check of the pipeline. Rupture detection is based on the resistance change when the wires come into contact with water. Then a special detection device connected to these wires registers a signal indicating that there has been a rupture in the pipeline.

2.5. Tehnika polaganja cjevovoda vrelovodne/toplovodne mreže Polaganje cijevi se vrši polaganjem u hladnom stanju ili polaganjem u toplom stanju. Za ova dva osnovna načina polaganja koristi se pet različitih tehnika. Izbor tehnike polaganja cjevovoda u hladnom ili toplom stanju vrši se u skladu sa lokalnim karakteristikama, odnosno ograničenjima. a) Polaganje cjevovoda u hladnom stanju Polaganje cjevovoda u hladnom stanju realizira se na tri načina: - polaganje cjevovoda u hladnom stanju bez

ograničenja dozvoljene dužine polaganja, ali sa ograničenjem temperature na najviše 85°C,

- konvencionalno polaganje cjevovoda sa ograničenjem dozvoljene dužine polaganja i maksimalnom temperaturom od 155°C,

- polaganje cjevovoda sa pogonskim samo-prednaprezanjem bez ograničenja dužine polaganja, ali sa ograničenjem temperature na najviše 130°C.

b) Polaganje cjevovoda u toplom stanju Polaganje cjevovoda u toplom stanju najčešće se realizira na dva načina: - polaganje cjevovoda sa termičkim

prednaprezanjem bez ograničenja dozvoljene dužine polaganja, ali sa prednaprezanjem u nezagrnutom rovu i sa ograničenjem temperature na najviše 155°C (temperatura predzagrijavanja = srednja temperatura);

2.5. Technique for laying the hot/warm water network Pipeline installation is done by laying in a cold state or laying in a warm state. Five different techniques are used for these two basic ways of pipeline installation. The choice of pipe laying in cold or warm conditions is done in accordance with local characteristics or limitations. a) Installation in a cold state Pipe laying in cold state is realized by one of the following three techniques: - pipe laying in cold condition without

limitation of the allowed laying length, but with a temperature limit up to 85°C,

- conventional laying with limitation of the allowed laying length and limited maximum temperature of 155°C,

- pipe laying with self pre-stressing without laying length limitation and with temperature limited up to 130°C.

b) Installation in a warm state Pipe laying in warm state is usually realized in two ways: - pipe laying with thermal pre-stressing with

no limitation to the allowed length of laying, but with pre-stressing in the open trench and with a temperature limit up to 155°C (preheating temperature = medium temperature);


189

- polaganje cjevovoda sa jednokratnim kompen-zatorom (EKO-sistem) bez ogranienja dozvoljene dužine polaganja, ali sa prednapre-zanjem u zagrnutom rovu i sa ogra-ničenjem temperature na najviše 140°C (temperatura predzagrijavanja barem 80°C), [3].

- pipe laying with onetime compensator (EKO-system) without limitation to the permissible length of laying, but with pre-stressing in the closed trench and with a temperature limit to a maximum of 140°C (preheating temperature at least 80°C), [3].

3. MJERENJE POTROŠNJE TOPLOTNE

ENERGIJE Za mjerenje potrošnje toplotne energije i ispravno fakturisanje računa krajnjim korisnicima sistema daljinskog grijanja koriste se mjerila toplotne energije koja se nazivaju kalorimetrima, slika 6. Mjerila se postavljaju na povratnom vodu toplovodne mreže krajnjih potrošača. Do sada je ugrađeno otprilike oko 250 kalorimetara za ukupno 3300 korisnika sistema daljinskog grijanja. Također, da bi se odredili gubici toplotne energije u sistemu, mjerila se ugrađuju i na povratnim vodovima poslije toplotne stanice u termoelektrani i poslije toplotnih podstanica. 3.1. Mjerilo toplotne energije (kalorimetar) Za mjerenje potrošnje toplotne energije u sistemu grijanja Kaknja koristi se uređaj (kalorimetar) Sonometer™ 1100. Sonometer™1100 je kompaktno, fiksno, ultrazvučno mjerilo energije, specijalno dizajnirano za primjene u aplikacijama grijanja, hlađenja ili kombiniranim grijanje-hlađenje aplikacijama u lokalnim i daljinskim energetskim sistemima [4].

3. THE MEASUREMENT OF HEAT ENERGY CONSUMPTION In order to measure the heat energy consumption and calculate the costs for the final users of the district heating system, heat meters, called calorimeters, are used. The calorimeters are installed on the return line of the warm water network of the final user. Approximately 250 calorimeters are installed for 3300 users of the district heating system till now. Also, to define the losses of heat energy in the system, calorimeters are installed on the return lines behind the heat station in the power plant and behind the thermal substations. 3.1. Heat energy meter (calorimeter) The measurement of heat energy consumption in the central heating system in Kakanj, the calorimeter Sonometer ™ 1100 is used. Sonometer ™ 1100 is a compact, fixed, ultrasonic energy meter, specially designed for applications in heating, cooling or combined heating-cooling applications in local and district power systems [4].

Slika 6. Ultrazvučno mjerilo toplotne energije (kalorimetar) marke Danfoss Figure 6. Ultrasonic heat energy meter (calorimeter) of brand Danfoss

Osnovne komponente ovog mjerila su: - ultrazvučno mjerilo protoka, - računsku jedinicu sa integrisanim hardverom

i softverom za mjerenje protoka, temperature i potrošnje energije,

- temperaturni senzor.

The basic components of this calorimeter are: - ultrasonic flow meter; - computer unit with integrated hardware and software for measurement of flow, temperature and energy consumption; - temperature sensor.


190

3.2. Ugradnja mjerila toplotne energije Zavisno od dizajna, mjerilo toplotne energije se ugrađuje u okviru hladne ili tople linije. Način ugradnje je definiran u uputstvu o upotrebi. Mjerilo toplotne energije se ugrađuje tako da smjer protoka odgovara smjeru koji pokazuje strelica na mjerilu protoka. Treba osigurati da mjerilo protoka uvijek bude napunjeno tekućinom po završetku ugradnje. Sekcije za umirenje protoka na ulazno-izlaznim cijevima nisu potrebne za mjerilo protoka. Mjerilo toplotne energije može biti ugrađeno u horizontalnom ili vertikalnom položaju, ali uvijek tako da se ne stvaraju mjehurići vazduha u mjerilu protoka. Za slabije protoke preporučuje se ugradnja pod nagibom od 90° u odnosu na cijev [5]. Sve navedeno prikazano je na slici 8.

3.2. Installation of calorimeters Depending on the design, the calorimeter is installed either on a cold or warm pipeline. The recommended way of installation is given in theinstruction on use. The heat meter is installed so that the flow direction corresponds to the direction indicated by the arrow on the flow meter. It should be ensured that the flow meter is always filled with liquid at the end of the installation. Sequential flow compartments for inlet-outlet pipes are not required for the flow meter. The calorimeter can be installed in a horizontal or vertical position but taking care that air bubbles are not being created in the flow meter. For lower flow rates, it is recommended to install the instrument under a 90° inclination to the pipe [5]. All this is shown in Figure 8.

Slika 8. Dozvoljeni načini i pogrešan način ugradnje mjerila

Figure 8. Allowed and incorrect ways of installation of the measuring instrument Također, treba osigurati da je mjerilo toplotne energije ugrađeno na dovoljnoj udaljenosti od mogućih izvora elektromagnetne interferencije (prekidači, elektromotori, fluorescentne lampe itd.). Preporučuje se ugradnja zapornih ventila prije i poslije mjerila toplotne energije, kako bi se kasnije olakšala demontaža mjerila. Mjerilo toplotne energije bi trebalo biti ugrađeno na pristupačnom mjestu radi lakšeg servisiranja i održavanja.

Also, it should be ensured that the heat meter is installed at a sufficient distance from possible sources of electromagnetic interference (switches, electric motors, fluorescent lamps, etc.). It is recommended that the shut-off valves be installed before and after the heat meter, in order to ease the calorimeter disassembly. The heat meter should be installed in an accessible place for easier servicing and maintenance.


191

4. MOGUĆNOSTI SMANJENJA POTROŠNJE TOPLOTNE ENERGIJE NA SISTEMU DALJINSKOG GRIJANJA

Većina korisnika SDG grada Kaknja nastoji optimirati potrošnju toplotne energije, uglavnom zbog finansijskih razloga. Ušteda toplotne energije i troškova može se postići ukoliko se vodi računa o toplotnoj izolaciji objekta i regulaciji potrošnje. Objekti koji ne posjeduju adekvatnu i odgovarajuću izolaciju i stolariju, odnosno koji ne spadaju u kategoriju energetsko-efikasnih (EE) objekata, zahtijevaju veću količinu toplotne energije za zagrijavanje, ali oni i dalje ne mogu da zadrže optimalnu temperaturu u unutrašnjosti objekta (20 ± 1°C). S druge strane, objekti kod kojih je urađena toplotna izolacija po odgovarajućem standardu mogu da uštede i do 40% toplotne energije. Također, toplotna energija se može uštedjeti zamjenom ručnih ventila specijalnim termostatskim ventilima koji se ugrađuju na ogrijevna tijela, odnosno na radijatore, slika 8. Omogućujući kvalitetnu regulaciju temeperature u unutrašnjosti objekta, ovi ventili mogu uštedjeti čak i do 10% toplotne energije. Stepen otvorenosti, odnosno zatvorenosti termostatskog ventila omogućava regulaciju temperature u prostoru koji se zagrijava prema podacima u Tabeli 1.

4. POSSIBILITIES OF REDUCTION OF HEAT ENERGY CONSUMPTION ON THE DISTRICT HEATING SYSTEM Most users of the DHS in Kakanj are trying to optimize the consumption of heat energy, mainly for financial reasons. The reduction of heat consumption and cost savings can be achieved by taking care of thermal insulation and consumption regulation. Buildings with inadequate insulation and carpentry, that is which do not belong to the category of energy-efficient (EE) facilities, require a higher amount of heat for heating, but they still can not maintain the optimal temperature inside the building (20 ± 1 °C). On the other side, the buildings with thermal insulation in accordance with the proposed standard can save the heat energy up to 40%. Also, the heat energy can be saved if manual valves are replaced by special thermostatic valves, which are installed on heating bodies, i.e. radiators, Figure 9. Their high-quality control of the interior temperature enables the heat energy saving up to 10%. The degree of openness or closure of the thermostatic valve enables the regulation of the temperature in the heated space according to the data in Table 1.

Slika 9. Termostatski ventil

Figure 9. Thermostatic valve Tabela 1. Regulacija temperature u zavisnosti od položaja termostatskog ventila Table 1. Temperature control depending on the position of the thermostatic valve

U najnovije vrijeme, za uštedu toplotne energije koriste se također i tzv. “balans” ventili koji omogućavaju ravnomjernu raspodjelu protoka tople vode.

In the recent times, for heat energy saving, the so-called "balance" valves that enable even distribution of the flow of warm water are also used.


192

Oni se postavljaju ispred ulaza u objekat i omogućuju regulaciju protoka koji je trenutno neophodan za zagrijavanje objekta. Na osnovu dugogodišnjih iskustava i prakse zaposlenih inženjera u ovoj firmi, dokazano je da se za povećanje temperature u unutrašnjosti objekta za 1°C mora angažovati otprilike 6% toplotne energije, odnosno potrebno je povećati protok tople vode. Pored toga, vanjska temperatura vazduha se također mora uzeti u obzir pri proračunu.

They are placed in front of the entrance to the building and allow flow control which is currently necessary for heating the facility. Based on many years of experience and practice of employees employed in this company, it has been proven that about 6% of the heat energy must be invested in the interior of the buildings by 1 ° C, i.e. it is necessary to increase the flow of warm water. In addition, the outside air temperature must also be taken into account when calculating the budget.

5. ZAKLJUČAK Zahvaljujući preventivnom održavanju i rekonstrukcijama magistralnog vrelovoda u Kaknju, koje se vrše svake godine po određenim dionicama, obezbjeđuje se dugotrajniji i sigurniji rad mreže toplifi-kacionog sistema. Na taj način omogućava se širenje mreže, a samim time i povećanje broja korisnika sistema daljinskog grijanja (SDG). U skladu s tim, planirana je izgradnja magistralnog vrelovoda od Termoelektrane „Kakanj“ u pravcu Sarajeva dužine od 37,9 km, na osnovu koga bi se mogli zagrijavati gradovi poput Visokog, Breze, Ilijaša i Sarajeva. Za taj projekat se predviđa toplotna stanica snage 300MW. Međutim, za postizanje tolike snage, neophodna je izgradnja bloka 8 na Termoelektrani „Kakanj“, jer postojeći blokovi 5, 6 i 7 ne mogu da proizvedu zahtijevanu snagu toplotne stanice. Isto tako, planira se proširenje gradske mreže kako bi se povećala energetska efikasnost, a samim time i smanjenje negativnog uticaja mini-kotlovnica na kvalitet zraka. Da bi se toplotna energija na racionalan način iskoristila, a isto tako i da bi se smanjila potrošnja toplotne energije, potrebno je koristiti prethodno navedene načine smanjenja potrošnje toplotne energije (adekvatna toplotna izolacija, ugradnja termostatskih i balans ventila), koji dovode do značajne uštede.

5. CONCLUSION Thanks to the preventive maintenance and reconstructions of the main hot water line in Kakanj, which are carried out every year on certain sections, the longer-lasting and safer operation of the heating system network is ensured. In this way, it is possible to expand the network, and thus increase the number of users of the district heating system (DHS). Accordingly, the construction of a main hot water pipeline from the Thermal Power Plant Kakanj towards Sarajevo is planned to be 37.9 km long, whereby cities like Visoko, Breza, Ilijaš and Sarajevo could be heated. For this project, a 300MW heat station is foreseen. However, to achieve so much power, it is necessary to build block 8 in the Thermal Power Plant Kakanj, as the existing blocks 5, 6 and 7 can not produce the required power. Also, the expansion of the city network is planned to increase energy efficiency and thus reduce the negative impact of mini-boilers on air quality. In order to use heat energy in a rational way, and also to reduce the consumption of heat energy, it is necessary to use the previously mentioned ways of reducing heat energy consumption (adequate heat insulation, thermostatic and balancing valves installation), which result in significant savings.

6. LITERATURA - REFERENCES [1] http://www.grijanje.co.ba// [2] Smanjenje specifične potrošnje primarne

energije povećanjem kogeneracije TE „Kakanj“, Idejni projekat, IPSA Institut, Sarajevo, decembar 2012.

[3] http://www.isoplus.de// [4] SONOMETER TM 1100, Tehnički list,

Danfoss, Danska, oktobar 2010.

[5] Ultrazvučno mjerilo toplinske energije, Instalacijski vodič, Danfoss, Hrvatska, juni 2010.

Coresponding author: Nedim Hodžić, Full professor University of Zenica, Faculty of Mechanical Engineering e-mail: [email protected] tel.: +387 32 449146

Mašinstvo 4(14), 193 – 202, (2017) M. Mrkić Bosančić et all: COMPARATION OF THE…

193

KOMPARACIJA SISTEMA DALJINSKOG GRIJANJA GRADOVA ZEMALJA U TRANZICIJI

COMPARATIVE OF THE DISTRICT HEATING SYSTEM OF

COUNTRIES IN TRANSITION

Maja Mrkić Bosančić1, Petar Gvero2, Jusuf Ibrulj3, AzrudinHusika4, Srđan Vasković5, 1Ministry of Industry, Energy and Mining of Republic of Srpska 2Faculty of Mechanical Engeneering,University of BanjaLuka 3Vatroteh inžinjering doo, Sarajevo 4Faculty of Mechanical Engeneering University of Sarajevo 5Faculty of Mechanical Engeneering, University of East Sarajevo Ključne riječi: Sistemi daljinskog grijanja, upoređivanje, zemlje u tranziciji Keywords: District heating systems, Comparation, Countries in transition Paper received: Paper accepted:

Rad objavljen na konferenciji REZIME Tokom druge polovine prošlog vijeka u Evropi su intenzivno građeni sistemi daljinskog grijanja (SDG) za snabdijevanje gradova i naselja toplotnom energijom. Uzmajući uobzir da su cijene energije u to vrijeme bile niske postojalo je ekonomsko opravdanje za izgradnju skupih infrastrukturnih distributivnih sistema. Posle prvog naftnog šoka sedamdesetih godina prošlog vijeka, došlo je do preispitivanja u potrošnji naftnih derivata (uglavnom mazuta) kao goriva u toplotnim izvorima SDG. Evropska unija ali i BiH u sektoru toplotne energije ima dugoročne ciljeve koji su usmjereni prema povećanju SDG na 30% do 2030., odnosno 50% do 2050 godine u onosu na sadašnji udio SDG od 12%. U radu se prezentuje dostupno (trenutno) stanje sistema daljinskog grijanja u BiH (Republici Srpskoj i FBiH). Rad obuhvata tehničko-tehnološke, snabdjevačke, distributivne, ekološke, ekonomske i tržišne parametre SDG gradova u BiH. Institucionalni i zakonodavni okvir prezentovan je u prethodnom radu. Komparacija parametara izvršena je u odnosu na gradove drugih zemalјa u tranziciji. Glavni zaključci su da je u gradovima BiH (i u RS i u FBiH) mala iskorišćenost sistema daljinskog grijanja, u upotrebi su zastarjele tehnologije a ulaganja u nove traže značajna investiciona sredstva, postoje mali pomaci u primjeni i uvođenju obnovljivih izvora energije poput biomase, te s tim u vezi je i mali uticaj na smanjenja emisija CO2, identifikovani su veliki gubici pri distribuciji toplotne energije, te tržišna situaciju koja s odlikuje još uvijek visokim cijenama energenata i potrošnja toplotne energije koja se još uvijek mjeri po površini prostora.

Conference paper

SUMMARY During the second half of the last century in Europe, district heating systems (DHS) have been built intensively to supply cities and settlements with heat energy. Taking into account that energy prices at that time were low, there was an economic justification for the construction of expensive infrastructural distribution systems. After the first oil shock of the seventies of the last century, there was a review of the consumption of petroleum products (mainly oil) as fuel in the heat sources of the DHS. The European Union, as well as Bosnia and Herzegovina, in the heat energy sector has long-term goals that are aimed at increasing the DHS to 30% by 2030, or 50% by 2050, in that of the current DHS of 12%. The present (current) state of the district heating system in Bosnia and Herzegovina (Republic of Srpska and Federation BiH) is presented. The paper covers the technical, technological, supply, distribution, environmental, economic and market parameters of DHS in BiH. The institutional and legislative framework is presented in the previous paper, the comparison of parameters was made in relation to the cities of other countries in transition. The main conclusions are that in the cities of BiH (in the RS and FBiH) the small utilization of the district heating system is outdated, Investing in new ones requires significant investment funds, there are small movements in the application and introduction of renewable energy sources such as biomass, and in this connection, there is a small impact on CO2


194

emission reductions, large losses in heat distribution have been identified, and a market situation that is distinguished still high energy prices and pricing of heat service dominantlly is based on the surface of the space.

1. UVOD Nakon promjene političkog i privrednog sistema 1989./90. tranzicione države srednje i Istočne Europe usmjerile su se prema ulasku u Evropsku Uniju što je između ostalog podrazumijevalo i tranziciju energetskog sektora. Te zemlje su ČeškaRepublika, Estonija, Mađarska, Poljska, Slovenija, Bugarska, Letonija, Litva, Rumunija, Slovačka i Albanija. Zemlje koje su nastale raspadom bivše SFRJ, takođe pripadaju ovoj grupi, ali su u tranziciju ušle kasnije, zbog ratnih dešavanja.Tranzicija energetskog sektora je složen proces koji zahtijeva solidnu pripremu koja obuhvata: analizu postojećeg stanjaovog sektora (teI sektoratoplifikacije koji obuhvataju I sisteme daljinskog grejanja), donošenje relevantne zakonske regulative, restrukturisanje, liberalizaciju tržišta, privatizaciju, strani kapital. U poslednjih desetak godina dvadesetog vijeka u većini tranzicionih zemalja [1] došlo je do urušavanja SDG u većini gradova, a uzroci za tu situaciju su skoro identični. Neki od njih su: postrojenja koja se na kraju svog radnog vijeka, zastarela tehnologija, neefikasna proizvodnja toplotne energije, visoka cijena energenata koji se koriste i problemi pri njigovom obezbjeđenju, energetski privredni subjekti opterećeni velikim brojem zaposlenih, neizolovane, stare, energetski neefikasne zgrade, troškovi koji premašuju prihode, značajno su utjecali na povećanje cijene grijanja, a posljedično i na smanjenje potrošnje. Kupovna moć kupaca je oslabila, što je daljinsko grijanje učinilo vrlo osjetljivim na sociološka i politička pitanja. Određen broj energetskih privrednih subjekata prestao je s pružanjem usluga isporuke toplotne energije djelomično ili potpuno. 2. MOTIVACIJA I CILJ RADA Glavna motivacija za nastanak ovog rada nalazi se u pitanju: Kakvo je stanje sistema daljinskog grijanja u gradovima BiH (FBIH i RS), i gdje se oni nalazeu odnosu da SDG gradova u drugim zemljama u tranziciji. Cilj rada je doći do kvalitativnih podataka i odnosa između navedenih parametara uzimajući u obzir da se ovakve komparacije uglavnom daju na nivou država.

1. INTRODUCTION After changing the political and economic system 1989/90 the transition countries of central and Eastern Europe focused on joining the European Union, which among other things also meant the transition of the energy sector. These countries are the Czech Republic, Estonia, Hungary, Poland, Slovenia, Bulgaria, Latvia, Lithuania, Romania, Slovakia and Albania. The countries that emerged from the disintegration of the former SFRJ also belong to this group, but went into transition after the war. The energy sector transition is a complex process that requires solid preparation that includes: adoption of relevant legislation, restructuring, market liberalization, privatization, foreign capital. In the last decade of the twentieth century in most transition countries [1], DHS have collapsed in most cities, and the causes for this situation are almost identical. Some of them are: plants that are at the end of their working lives, obsolete technology, inefficient production of heat, high cost of energy used and problems with their security, energy business entities burdened with a large number of employees, uninsulated, old, energy-inefficient buildings, costs that exceed revenues have significantly influenced the increase in the cost of heating and, consequently, the reduction in consumption The purchasing power of the buyers has weakened, making district heating very sensitive to sociological and political issues. Certain number of energy companies has ceased to provide partial or complete delivery of heat supply services. 2. MOTIVATION AND OBJECTIVE OF WORK The main motivation for the emergence of this work is: What is the state of the DHS in the cities of BiH (FBiH and RS), and where they are in relation to cities DHS in other countries in transition. The aim of the paper is to obtain qualitative data and relations between the mentioned parameters, taking into account that such comparisons are mostly given at the level of the state.


195

3. STANJE SISTEMA DALJINSKOG GRIJANJA U GRADOVIMA BiH

U Republici Srpskoj (RS) toplotna energija se najvećim dijelom proizvodi u toplanama, oko 94%, a ostatak u Termoelektrani Ugljevik [2].Primarni energenti koji se koriste u ovom sektoru su lož ulje i ugalj. Lož ulje je najzastupljenije, s udjelom u proizvodnji toplotne energije od 42%, ali se njegova potrošnja, od 2011. do 2015. godine smanjivala prosječnom godišnjom stopom od -10,4%. Ugalj sa udjelom od 31% je drugi energent po zastupljenosti u sektoru toplifikacije, te se u periodu od 2011. do 2015. godine zadržao istinivo proizvodnje toplotne energije iz tog energenta. Veliko povećanje proizvodnje toplotne energije iz biomase zabilježeno je u istom periodu, kao posljedica puštanja u rad nove toplane u Prijedoru, i to s prosječnom godišnjom stopom rasta od 31,2%. Prirodni gas je malo zastupljen, s udjelom od 4%, te se koristi samo u Zvorniku, a u narednom periodu iu Bijeljini [2]. Za razliku od Republike Srpske u Federaciji Bosne i Hercegovine (FBiH) se snabdijevanje toplotnom energijom vrši iz obližnjih termoelektrana, energana ili industrijskih kapaciteta. Primarni energenti u FBiH su prirodni gas (53,5%), ugalј (31,5%) i lož ulјe (10,8%) [3]. Bio masa je zastupljena, s 4,2% [3]. Toplotna energija u Republici Srpskoj se uglavnom koristi u domaćinstvima, koja sačinjavaju oko 76% finalne potrošnje toplotne energije, dok je taj iznos u FBiH oko 78%. Toplotna energija u oba entiteta se isključivo isporučuje za grijanje prostora i nema snabdijevanja potrošnom toplom vodom. U RS trenutno postoji 11 privredih društava koja se bave proizvodnjom, distribucijom i snabdijevanjem kupaca toplotnom energijom. Svi su u javnom vlasništvu i nalaze se u: Banja Luci, Doboju, Prijedoru, Gradiškoj, Palama, Istočnom Sarajevu,Brodu, Sokocu, Čelincu, Bijeljini i Zvorniku. U FBiH privredna društva koja distribuiraju toplotnu energiju nisu njeni proizvođači a i vlasništvo je drugačije. U tabeli 1. su prikazana privredna društva koja se bave proizvodnjom, distribucijom i snabdijevanjem krajnjih kupaca toplotnom energijom.

3.1. Tehničko-tehnološki parametri

U Dodatku A, Tabela 1. prikazuje tehničko-tehnološke parametre [4,5,6].

3. THE STATE OF CITY DHS IN BOSNIA AND HERCEGOVINA In Republica of Srpska (RS), thermal energy is mostly produced in heating plants, around 94%, and the rest in Ugljevik Thermal Power Plant. [2] Primary energy sources used in this sector are fuel oil and coal. Fuel oil is the most represented, with a 42% share in heat production, but its consumption declined from 2011 to 2015 by an average annual rate of -10.4%. Coal, with a share of 31%, is the second energy source in terms of its share in the sector, and in the period from 2011 to 2015, the true production of thermal energy from that energy source was maintained. A large increase in the production of thermal energy from biomass was recorded in the same period, as a consequence of the commissioning of a new heating plant in Prijedor, with an average annual growth rate of 31.2%. Natural gas is slightly represented, with a share of 4%, and is used only in Zvornik, and in the following period in Bijeljina [2]. Unlike the Republic of Srpska, the Federation of Bosnia and Herzegovina (FBiH) supplies heat from the nearby thermal power plants, energy or industrial capacities. Primary energy in the FBiH is natural gas (53.5%), coal (31.5%) and fuel oil (10.8%). [3]. Biomass is inactive, with 4.2% [3]. Thermal energy in the Republic of Srpska is mainly used in households, accounting for around 76% of the final consumption of heat, while this amount in FBiH is 78%. Thermal energy in both entities is exclusively supplied for space heating and there is no supply of hot water. In the Republic of Srpska, there are currently 11 companies that are engaged in theproduction, distribution and supply of heat energy customers. They are all publicly owned and are located in: Banja Luka, Doboj, Prijedor, Gradiška, Pale, Istočno Sarajevo, Brod, Sokolac, Čelinac, Bijeljina and Zvornik. In FBiH, companies that distribute heat energy are not its producers and ownership is different. In the continuation of the work, technical, technological, supply, distribution, ecological, economic and market parameters of some of them are given. 3.1. Technical-technological parameters In Appendix А, Table 1. shows technical-technological parameters [4,5,6].


196

Četiri generacije distribucije toplote su definisane u radu. [7]. Sa svakom novom generacijom sistema daljinskog grijanja temperatura ogrevnog medija je padala: za prvu generaciju je karakteristično da je medij bio para temperature 300ºC, u drugoj generaciji vrela voda temperature 130ºC, u trećoj generaciji topla voda temperature 80ºC, a u zadnjoj četvrtoj generaciji medij je nisko-temperaturna voda temperature 50ºC. Promatrajući stranu proizvodnje, u prvoj generaciji kao energent koristilo se lož ulje, koje se u drugoj generaciji proširilo na gas, i kogeneracijska postrojenja na gas i ugalj, a u trećoj generaciji upotrebljavana je biomasa, industrijski viškovi i spaljivanje otpada. U četvrtoj generaciji daljinskog grijanja više se ne koriste kogeneracijska postrojenja ili samostalna postrojenja na gas i ugalj, već se za proizvodnju toplotne energije koriste kogeneracijska postrojenja za spaljivanje otpada, industrijski viškovi, kogeneracije na biomasu i biogas, viškovi električne energije iz vjetra, geotermalna i solarna postrojenja. Glavna karakteristika četvrte generacije je da će se toplota distribuira s nižim temperaturama nego što se primjenjuje u trećoj generaciji. Distributivna mreža može distribuirati toplotu proizvedenu iz različitih energetskih izvora, od kojih se u posljednje vrijeme sve više koriste industrijski viškovi, toplota iz kogeneracija na biogoriva, geotermalna energija, solarna energija,te i viškovi električne energije (posebno OIE kao što su vjetroelektrane, koje svoju energiju odlažu skladištenjem toplotne energije kako u dnevnim tako i u sezonskim skladištima). Za postizanje razmatranih ciljeva izazov će biti uravnotežiti ponudu i potražnju za energijom, za što su vrlo pogodna skladišta toplotne energije. 3.2. Snabdijevački parametri U dodatku A, Tabela 1. prikazani su snabdjevački parametri [3,4]. 3.3. Proizvodni i distributivni parametri U dodatku A, Tabela 1. prikazani su proizvodni I distributivni parametri [4,5,6], a dio koji se odnosi na rekonstrukciju se može naći [6]. 3.4. Ekološki parametri U skladu sa zakonodavstvom u oblasti zaštite vazduha, 2016. godine, BiH je nastavila da prati emisije zagađujućih materija u vazduhu iz termoelektrana - sumpor dioksid (SO2), azotni oksidi (NOx), čvrste čestice i ugljen-dioksid (CO2).

The four generations of heat distribution are defined in the paper [7]. With each new generation of the DHS, the temperature of the heating medium fell: for the first generation it is characteristic that the medium was a temperature of 300 ° C, in the second generation a hot water temperature of 130 ° C, in the third generation of hot water temperatures of 80 ° C, and in the last fourth generation the medium is low temperature water temperature 50ºC. Observing the production side, in the first generation as a fuel, fuel oil, which in the second generation expanded to natural gas, and cogeneration plants on gas and coal, was used in the third generation, biomass, industrial surpluses and waste incineration. In the fourth generation of district heating, cogeneration plants or independent gas and coal plants are no longer used, but cogeneration plants for waste incineration, industrial surpluses, biomass and biogas cogenerations, wind surpluses from wind, geothermal and solar The main characteristic of the fourth generation is that heat will be distributed at lower temperatures than in the third generation. The distribution network can distribute heat produced from various energy sources, of which industrial surpluses, heat from cogeneration to biofuels, geothermal energy, solar energy, and electricity surpluses (especially RES such as wind power plants, which are energy is deposited by storing heat energy in both daily and seasonal warehouses). In order to achieve these objectives, the challenge will be to balance supply and demand for energy, for which they are very suitable heat storage facilities. 3.2. Supply parameters In Appendix А, Tabela 1.shows supply parameters [3,4]. 3.3. Production and distribution parameters In Appendix А,Table 1.shows production and distribution parameters [4,5,6], and part related to reconstruction can be found on [6]. 3.4. Environmental parameters In accordance with the legislation in the field of air protection, in 2016, BiH continued to monitor emissions of pollutants in the air from thermal power plants - sulfurdioxide (SO2), nitrogen oxides (NOx), solid particles, and carbon dioxide (CO2).


197

Emisije zagađujućih materija u vazduh i emisije CO2 iz TE Tuzla i TE Kakanj [6,9] za 2016. su date u [6]. U Dodatku A, u Tabeli 1. prikazane su emisije CO2 u zgradarstvu u BiH [9] . 3.5. Ekonomski parametri U finansiranju sektora daljinskog grijanja RS i FBiH mogu se koristiti tri osnovna modela: - Javno finansiranje, privatno finansiranje i

mešano finansiranje (partnerstvo između javnog i privatnog sektora).

U modelu javne finansije dominantna je uloga javnog sektora (centralne vlade, lokalne i regionalne samouprave, javnih preduzeća, fondova i agencija). Privatno finansiranje je rasprostranjeno zbog nejednakosti između rastućih energetskih potreba i troškova izgradnje energetske infrastrukture s jedne strane i ograničenih finansijskih mogućnosti javnog sektora i javnog sektora. Partnerstvo u javnom i privatnom sektoru kao model mešovitog finansiranja za razvoj energetskog sektora sprovodi se u okviru različitih struktura vlasništva i upravljanja. Deljenje rizika, partnerstvo pruža niz pogodnosti za privatni i javni sektor. 3.6. Tržišni parametri U Prilogu A Tabela 1., prikazuje prosječnu ciјenu grijanja za domaćinstva u BiH i period u kojem se usluga plaća [6]. 4. STANJE SDG U GRADOVUIMA

ZEMALJA U TRANZICIJI Ispod su navedeni parametri nekoliko gradova u Estoniji (Tallin, Haapsalu, Jõgeva, Keila, Kärdla, Rapla i Valga) i Letonija (Riga). 4.1. Estonia U Estoniji ima 226 lokalnih jedinica, od kojih 151 koristi DHS. Godišnja potrošnja toplotne energije u Estoniji iznosi oko 4,6 TWh [7]. U Dodatku A, Tabela 1. pokazuje tehničko-tehnološke parametre, proizvodnju i distribuciju, parametre snabdevanja, emisiju CO2 u zgradarstvu i tržišne parametre [8,9,10, 12,13]. Većina postrojenja u Estoniji funkcioniše u režimu kogeneracije. Voda proizvedena u postrojenju se prodaje mrežama daljinskog grejanja ili industrijskim potrošačima koji se nalaze blizu postrojenja. Ova tabela sadrži listu radnih postrojenja za proizvodnju kogeneracije sa sopstvenim toplotnim (MWt) i električnim kapacitetom (MWe). 60% domaćinstava koristi SDG.

Emissions of polluting substances into air and CO2 emissions from TPP Tuzla and TPP Kakanj [6,9], for 2016 are given in [6] In Appendix А, Table 1. shows the CO2 emissions in the building sector in BiH city [9]. 3.5. Economic parameters In the financing of the district heating sector of the RS and the FBiH, three basic models can be used: - Public funding, Private financing and Mixed

financing (partnership between the public and private sectors) In the public financing model, the public sector (central government, local and regional self-government, public companies, funds and agencies) has a dominant role.

Private funding is widespread due to the disparity between rising energy needs and the costs of building energy infrastructure on the one hand and limited financial opportunities public sector and public sector. The public and private sector partnership as a model of mixed financing for the development of the energy sector is being implemented within the various ownership and management structures. By sharing risk, the partnership provides a range of benefits to both the private and the public sector. 3.6. Market parameters In Appendix A Table 1. shows average heating price for households in BiH and the period in which the service is paid [6] 4 THE SITUATION OF DHS IN THE CITY OF COUNTRIES IN TRANSITION Below are some parameters of several cities in Estonia (Tallin, Haapsalu, Jõgeva, Keila, Kärdla, Rapla, and Valga) and Latvia (Riga). 4.1. Estonia In Estonia there are 226 local units, of which 151 are using DHS. The annual consumption of heat energy in Estonia is about 4.6 TWh [7]. In Appendix A,Table A. shows shows technical-technological parameters, production and distribution, supply parameters, emission of CO2 in building sector and market parameters [8,9,10, 12,13]. Most of the plants in Estonia operate in the cogeneration regime. The heat produced in the plant is sold to district heating networks or to industrial consumers located near the plant. The following table contains a list of operational plants for the production of cogeneration with its own thermal (MWt) and electrical capacity (MWe). 60% of households use DHS.


198

Postrojenje za spaljivanje otpada - elektrana Iru, od 2013. godine, moderna i efikasna jedinica za spaljivanje otpada koja proizvodi toplotu i električnu energiju iz mješovitog komunalnog otpada. Karakteristike postrojenja: Količina otpadnog otpada je 120 000 - 220 000 tona godišnje, nominalna snaga 10-18 MW, kapacitet toplote od 25-50 MWt, izlazna snaga električne energije godišnje 70-140 Gwhe, izlaz toplote 200-310 GWht godišnje. Izgradnja fabrike koštala je 1-1,5 milijardi krona. 4.2. Letonia Letonija (Letonija) je jedan od lidera u EU za višespratne stambene zgrade koje koriste SDG. Kao rezultat, SDG je važan segment Latvijske ekonomije, sa ukupno 74 sistema daljinskog grejanja. Glavno tržište daljinskog grijanja nalazi se u devet najvećih gradova, koji pokrivajući 75% ukupnog tržišta. Letonijska prestonica Riga, sa populacijom od oko 700.000 stanovnika, čini oko pola tržišnog udjela na daljinskom grijanju. Toplotna energije proizvedena u 663 kotlovnicama i 1,32 kogeneracijska postrojenja ostvarila je 7.46 TWh. Tokom poslednje decenije, daljinsko grejanje u Letoniji je doživjelo neprekidan pomak ka obnovljivoj energiji, a dominacija prirodnog gasa smanjena upotrebom drvnog čipsa i drugih obnovljivih izvora energije (OIE). U 2015. godini udio potrošnje prirodnog gasa, naftnih derivata i uglja u kotlovima za centralno grijanje (isključujući CHP) u odnosu na 2008. je smanjen za 26,5%, 2,6% i 0,28% respektivno. U međuvremenu, udio je povećan za 28,9% [11]. U Dodatku A, u Tabeli 1. prikazani su tehničko-tehnološki parametri, proizvodni i distributivni parametri, parametri snabdevanja, emisija CO2 u zgaradstvu i tržišni parametri [11,12]. U cilju poboljšanja energetske efikasnosti, JSC "Rīgas siltums" je primijenio niz mjera od kojih su dva od velikog značaja i kao primjeri dobre prakse preporučeni su za prenos u druge sisteme za snabdevanje toplotom i sažeti u prijedlogu "Oporavak toplote iz dimnih gasova i tokovi hlađenja u postrojenjima za proizvodnju energije", a koji su uključeni u katalog "Najbolje prakse za pametan grad" koke je pripremila opštinska agencija REA 2013. godine. Primeri dobre prakse su dati u [9].

Waste incineration plants-Iru Power Plant, since 2013, a modern and efficient waste incineration unit that produces heat and electricity from mixed municipal waste. Characteristics of the plant: The amount of waste burned is 120 000 - 220 000 tons per year,• nominal electric power 10-18 MW, Heat capacity 25-50 MWt, Output power of electricity per year 70-140 Gwhe, heat output 200-310 GWht per year. The construction of the factory cost 1-1.5 billion krona. 4.2. Letonia Latvia (Letonia) is one of the leaders in the EU for multi-story residential buildings served by district heating. As a result, district heating is an important segment of the Latvian economy, with a total of 74 district heating systems. The main district heating market is within the nine largest cities, covering 75% of the total market. The Latvian capital Riga, with a population of nearly 700,000, accounts for approximately half of the district heating market share.The heat energy for sale produced in 663 boiler houses and132 cogeneration plants having generated 7.46 TWh. The graph below demonstrates that 30% of the residential heat demand in 2015 was supplied through district heating. During the last decade, district heating in Latvia experienced continuous shift towards renewable energy and the domination of natural gas has been diminished by wood chips and other renewable energy products. In 2015, the share of natural gas, oil products and coal consumption in the district heating boilers (excluding CHP) compared to 2008 has decreased by 26.5%, 2.6% and 0.28% respectively. In the meantime, the share of RES has increased by 28.9% [11]. In Appendix A, Table 1. shows technical-technological parameters, production and distribution, supply parameters, emission of CO2 in building sector and market parameters [11,12]. With a view to improving energy efficiency, JSC “Rīgas siltums” has implemented a number of measures in the heat sources two of which are of major importance and as best practice examples have been recommended for transfer to other heat supply systems and summarized in the proposal “Recover of heat from flue gas and cooling flows in energy production plants” included in the ecatalogue “Best practice projects for a smart city” prepared by the municipal agency REA in 2013 The examples of good practice are given in [9].


199

5. REZULTATI KOMPARACIJE SDG PARAMETARA

Prema Lukoseviciusu [1] u zemljama u tranziciji, naročito u onima u hladnoj klimi, velika je upotreba daljinskog grijanja i korištenja velikih kogeneracionih postrojenja. Ovo se znatno promenilo krajem dvadesetog vijeka kada je došlo do značajnog pada broja potrošača. Stare fabrike, visoke cijene energije, korisnici energije opterećeni velikim brojem zaposlenih, neizolovanih i starih zgrada, značajno su uticali na povećanje cijena grijanja i, uzročno, na smanjenje potrošnje. Stanje SDG u BiH na osnovu poređenja parametara SDG u gradovima Estonije i Letonije može se opisati na sljedeći način: Starost i niska efikasnost proizvodnih kapaciteta, Zastarela tehnologija, Starost i veliki gubici tople vode u mreži, Teškoće u mjerenju, računanju i prikupljanju isporučene toplotne energije za pojedinačne subjekte, Visoke cijene goriva (uglja, nafte i prirodnog gasa), Korišćeni energetski proizvodi uglavnom su od uvoza, Neadekvatno naplata usluga vodi do direktnog neadekvatnog ulaganje u sektor. Dodatni problem takvih sistema je da se fokus stavlja na proizvodni i tehnički rad, a ne na potrebe potrošača [13]. Tehnička i ekonomska situacija preduzeća za proizvodnju i distribuciju toplote je teška zbog nemogućnosti “pokrivanja” troškova poslovanja, zbog primjene cijena, tj. tarifa koje ne pokrivaju sve troškove. Takvo stanje ne dozvoljava modernizaciju postojećih sistema, nedostataju podsticaji, snažan jer politički uticaj, nepredvidivi su propisi, loša ekonomska održivost i niska konkurentnost odbija privatne investitore da ulažu u sektor daljinskog grijanja, visoka potrošnja energije u zgradama sa slabom izolacijom, bez mogućnost regulisanja potrošnje toplote i niska kupovna moć većine krajnjih kupaca, što je učinilo da je daljinsko grijanje jedva dostupno, sistematično planiranje razvoja i izgradnje lokalne energetske infrastrukture je još uvijek retko, renoviranje zgrada (toplotna izolacija radi uštede energije ) vrši se veoma sporo, visoki su troškovi održavanja za veće postrojenja sa malom raspodjelom količine energije u velikom mrežnom sistemu i većim gubicima u procentima u odnosu na veću količinu potencijalno isporučene energije, što dovodi do akumulacije gubitaka, male diverzifikacije izvora energije u proizvodnim pogonima, naročito mali udeo OIE,

5. RESULTS OF COMPARATION OF THE DHS PARAMETERS According to Lukosevicius [1] in transition countries, especially in those in the cold climate, district heating and the use of large cogeneration plants are of great use. This changed significantly at the end of the twentieth century when there was a significant drop in the number of consumers. Old plants, high energy prices, energy users burdened with a large number of employees, uninsulated and old buildings, significantly influenced the increase in heating prices and, consequently, the reduction in consumption. The state of the district heating system in BiH based on the comparison of DHS parameters in the cities of Estonia and Latvia can be described as follows: Age and low efficiency of production capacities, Outdated technology, Age and large losses in hot water and heat networks, Difficulties in measuring, calculating and collecting the delivered heat energy for individual entities, High prices of fuels (coal, oil and natural gas), The energy products used are mainly from imports,• Inadequate collection of services leads to a direct incentive to invest in the sector. An additional problem of such systems is that the focus is placed on production and technical work, not on the needs of consumers [13]. The technical and economic situation of the companies for the production and distribution of heat is difficult due to the work "below the cost of coverage", due to the application of prices, i.e. Tariffs that do not cover all costs. Such a state does not allow the modernization of existing systems, lack of incentives, strong political influence, unpredictable regulations, poor economic viability and low competitiveness refuse private investors from investing in the district heating sector, high energy consumption in buildings with poor insulation, without the ability to regulate heat consumption and low purchasing power of most end customers, which made district heating barely accessible, systematic planning for the development and construction of local energy infrastructure is still rare, the renovation of buildings (thermal insulation for the purpose of energy savings) is carried out very slowly, high maintenance costs for larger plants with a small distributed amount of energy in a large network system and greater losses in percentage over a larger amount of potentially delivered energy, leading to accumulation of losses, small diversification of energy sources in production plants, especially small share of RES,


200

nedostatak kogeneracije na biogas, geotermalne i solarne energija, neiskorišćena upotreba preostale toplote otpadnih voda, toplota sagorevanja otpada i političkih odluka ili nove obaveze za sektor daljinskog grejanja često nisu praćene neophodnim finansijskim sredstvima.ž 6. ZAKLJUČAK U BiH,sistemi dalјinskih grijanja su pozicionirani u većim gradovima. SDG u BiH su jako različiti uzimajući u obzir različite aspekte. S aspekta vrste energenta koji se koristi, Sarajevo i Zvornik koriste prirodni gas. Razlog tome je lociranost ovih gradova uz mrežu prirodnog gasa. Banja Luka i Brod koriste mazut, koji je mnogo godina unazad bio najskuplji izvor energije za grijanje. Zatim, veliki broj sistema daljinskih grijanja koristi ugalj kao glavni energent (Doboj, Tešanj, itd.). U posljednje vrijeme izvršena je obnova postojećih sistema na biomasu (Sokolac i Pale), te prelazak nekih sistema (djelimično ili potpuno) sa mazuta na biomasu (Prijedor i Banja Luka). Posebnu grupu čine sistemi daljinskog grijanja koji koriste toplotu iz energetskih i industrijskih postrojenja (Zenica, Kakanj, Tuzla i Lukavac). Ovi sistemi daljinskog grijanja su održivi uglavnom zbog niskih cijena toplote koju primaju iz kogeneracijskih postrojenja. Najveći dio privrednih društava iz sektora daljinskog grijanja su javna preduzeća koja finansiraju lokalne zajednice u kojima se nalazi sistem daljinskog grijanja. To znači da su ova preduzeća odgovorna opštinskim i gradskim skupštinama.Problem svih SDG je predimen-zionisanost (postrojenja su dimenzionisana za mnogo veći broj korisnika nego što se sada snabdijeva). Pored toga, metoda proračuna toplotnih potreba u ovim sistemima je bila bazirana na tome da sistem može adekvatno grijati objekte i pri ekstremno niskim temperaturama. Uzimajući u obzir da većina SDG uglavnom isporučuje toplotu samo za potrebe grijanja, postrojenja rade punim kapacitetom svega 20 % na nivou godine. Dodatni problem je i niska energijska efikasnost objekata. Imajući u vidu tarifni sistem (u većini sistema daljinskog grijanja plaćanje se vrši po m2 grijanog prostora), niska energetska efikasnost objekata ima jako negativan uticaj na održivost sistema daljinskih grijanja.Mreža daljinskog grijanja kod većine sistema u BiH je u lošem stanju. Pored visokih gubitaka toplote, problem predstavljaju i gubici vrele vode zbog curenja.

lack of cogeneration on biogas, geothermal and solar energy, unused use of residual heat of waste water, heat of combustion of waste and political decisions or new obligations for the district heating sector are often not accompanied by the necessary financial. 6. CONCLUSION In BiH, district heating systems are positioned in larger cities. DHS in BiH city are very different considering different aspects. From the aspect of the energy source used, Sarajevo and Zvornik use natural gas. The reason for this is the location of these cities along the natural gas network. Banja Luka and Brod are using oil fuel, which for many years was the most expensive source of energy for heating. Then, a large number of district heating systems use coal as the main energy source (Doboj, Tesanj, etc.). Renewal of existing biomass systems (Sokolac and Pale) has recently been carried out, as well as the transition of some systems (partly or completely) to biomass (Prijedor and Banja Luka). The special group consists of district heating systems that use heat from the power and industrial plants (Zenica, Kakanj, Tuzla and Lukavac). These district heating systems are viable mainly due to the low heat prices they receive from the cogeneration plants. The largest parts of the district heating companies are public companies that finance local communities in which there is a district heating system. This means that these companies are responsible for municipal and city assemblies. The problem of all DHS is predisposition (the facilities are dimensioned for a much larger number of users than they are now supplying). In addition, the method of calculating heat needs in these systems was based on the fact the system can adequately heat objects at extremely low temperatures. Taking into account that most DHS mainly deliver heat only for heating purposes, the plants work full capacity by only 20% at year level. An additional problem is the low energy efficiency of objects. Taking into account the tariff system (in most of the district heating systems the payment is done per m2 of heated space), the low energy efficiency of the facilities has a very negative impact on the sustainability of the district heating system. District heating in most BiH systems is in poor condition. In addition to high heat losses, the problem is water leakage losses due to leakage.


201

Skoro svi sistemi daljinskog grijanja s ciljem povećanja korištenja raspoloživih kapaciteta vrše širenje mreže daljinskog grijanja. Aktuelan je i trend prelaska sa uglja na biomasu i to zbog trenda porasta cijena uglja za daljinska grijanja, a s druge strane dolazi i do postepenog razvoja tržišta biomase, čiji su troškovi niži od uglja. Osnovna barijera za razvoj projekata daljinskog grijanja je stara infrastruktura ili potpuno odsustvo infrastrukture i prestanak rada postrojenja (fabrika) koje su isporučivale toplotu, a koje su bile uglavnom iz drvnoprerađivačkog sektora (kao na primjer u Milićima, Vlasenici, Olovu, Kladnju itd.). Zbog svega navedenog proizilazi potreba investiranja u sisteme daljinskog grijanja kroz ulaganje u rekonstrukciju, revitalizaciju i modernizaciju postojećih sistema daljinskog grijanja i uspostavljanje novih održivih sistema daljinskog grijanja, ali opštine nemaju mogućnost finansiranja ovakvih projekata zbog nedovoljnih i nerazvijenih kapaciteta za pripremu i implementaciju takvih projekata kao i zbog nemogućnosti zaduženja zaduženja s obzirom na postojeća zaduženja. Preko 80% stambenog fonda koji se toplotnom energijom snabdjeva iz sistema daljinskog grijanja, troškove za energiju plaća paušalno, odnosno po m2 grijane površine. Privredna društva za isporuku toplotne energije, djeluju po principu proizvodnje i isporuke energije (MWh), te „tarifnog sistema“ naplate KM/m2. Oko 20 % površine stambenog sektora u BiH na daljinskom grijanju, energiju plaća po utrošku gdje pojedine toplane imaju svoje tarifne stavove. Preduslov za motivisanje krajnjih korisnika za uštedu toplotne energije jeste omogućavanje plaćanja po utrošku, što je jasno i definisanom EU direktivama. Plaćanje preuzete energije po utrošku ne znači da će se plaćati manje, nego da će se plaćati preuzeta/potrošena količina energija.

Almost all district heating systems with the aim of increasing the use of available capacities make the expansion of the district heating network. There is also a trend of transition from coal to biomass due to the trend of coal prices for district heating, and on the other hand, there is a gradual development of the biomass market, whose costs are lower than coal. The basic barrier for the development of district heating projects is the old infrastructure or the complete absence of infrastructure and the cessation of the heat supply plants that were mainly from the wood processing industry (such as in Milić, Vlasenica, Olovo, Kladanj, etc.).The demand for heat energy in some transition countries has started to grow again. Due to all of this, there is a need to invest in district heating systems by investing in the reconstruction, revitalization and modernization of existing district heating systems and the establishment of new sustainable district heating systems, using local energy sources and increasing RES but cities do not have the possibility to finance such projects due to insufficient and underdeveloped capacities for the preparation and implementation of such projects as well as due to the impossibility of debiting with regard to existing operational debts. Over 80% of the housing stock that is supplied with heat from the district heating system, the energy costs pay flat, or per m2 of heated space. Businesses for the supply of heat energy operate according to the principle of production and supply of energy (MWh), and the tariff system of KM/m2 collection. Approximately 20% of the residential sector in BiH on district heating, energy is paid on the expense where individual heaters have their own tariff attitudes. The precondition for motivating end-users to save energy is to enable payment by payment, which is clearly defined in EU directives. Paying the downloaded energy per expense does not mean that it will be paid less, than the downloaded/consumed amount of energy will be paid.

6. LITERATURA - REFERENCES [1] Lukosevicius, V., Werring, L. (2011):

Regulatory Implications of District Heating, Budimpešta: ERRA.

[2] Ministarstvo industrije energetike I rudarstva Republike Srpske, Vlada Republike Srpske (2016) Energetski bilans Republike Srpske plan za 2016.

[3] Federalni zavod za statistiku (2016) StatističkilјetopisFBiH 2016.

[4] Ministarstvo industrije energetike I rudarstva RepublikeSrpske, Narodna Skupština Republike Srpske (2012). Strategija razvoja energetike Republike Srpske do 2030 god.

[5] Federalno Ministarstvo energije rudarstva i industrije, Vlada Federacije Bosne i


202

Hercegovine (2009) Strateški plan i program razvoja energetskog sektora Federacije BiH.

[6] WEB strane privrednih društava:http://www.bltoplana.com/, https://toplanadoboj.ba/, http://www.toplanapd.com/, http://www.ieegroup.net/projekti.html, http://www.jpradlukavac.ba/, http://www.grijanjetuzla.ba/, http://www.grijanje.co.ba/, http://grijanjezenica.ba/,http://toplane-sa.co.ba/, http://toplana-tesanj.com/bs/ http://www.elektroprivreda.ba/stranica/te-tuzla, pristupljeno u periodu 01.09.-15.09.2017.godine.

[7] www.taastuvenergeetika.ee, pristupljeno 15.09.2017.godine.

[8] https://www.utilitas.ee/en/news/a-record-number-of-new-consumers-subscribed-to-district-heating-in-2016/

[9] SEAP Akcioni plan energetski održivog razvoja opština koje su obuhvaćene analizom (Banja Luka, Prijedor, Zvornik, Tuzla, Zenica, Kakanj, Tallin, Riga).http://www.covenantofmayors.eu/actions/sustainable-energy-action-plans_en.html, pristupljeno u periodu 01.09.-15.09.2017.godine.

[10] Ministry of Economic Affairs and Communications Estonia, (2016), Possibilities of efficiency in heating and cooling in Estonia.

[11] https://www.euroheat.org/knowledge-centre/district-energy-latvia/, pristupljeno 20.09.2017.godine.

[12] www.rea.riga.lv, pristupljeno 25.09.2017. godine.

[13] Lončar, D., Riđan, I. (2012): Medium term development prospects of cogeneration district heating systems in transition country – Croatian case, Energy, Vol. 48, Issue 1, pages 32-39.

[14] Connoly, D., Lund, H., Mathiesen, B., Werner, S., Möller, B., Persson, U., Boermans, T., Trier, D., Østergaard, P., Nielsen, S. (2014): Heat Roadmap Europe: Combining district heating with heat savings to decarbonise the EU energy system, Energy Policy, Vol. 65, pages 475-489.

[15] Golušin, M., Munitlak Ivanović, O. (2011): Kyoto protocol implementation in Serbia as precognition of sustainable energetic and economic development, Energy Policy, Vol 39, Issue 5, pages 2800-2807.

Coresponding author: Azrudin Husika, Full professor University of Sarajevo, Faculty of Mechanical Engineering Sarajevo e-mail: [email protected] tel.: +387 33 729800

Mašinstvo 4(14), 203 – 212, (2017) N. Turčinović: ANALYSIS SOLUTION OF CUT USING…

203

ANALIZA RJEŠENJA KOSINE USJEKA PRIMJENOM METODA ARMIRANOG TLA, ČAVLANJA I IZRADE POTPORNOG ZIDA

ANALYSIS SOLUTION OF CUT USING METHODS OF REINFORCED

WALL, SOIL NAILING AND MAKING RETAINING WALL

Turčinović Nejra University of Zenica, Polytechnic faculty Ključne riječi: analiza, armirano tlo, najpovoljnije rješenje Keywords: analysis, best solution, reinforced wall Paper received: 13.09.2017. Paper accepted: 05.12.2017.

Stručni rad REZIME U radu su opisane analize rješenja kosine usjekna na autocesti. Primijenjene su tri metode izrade potporne konstrukcije, a to su armirano tlo HDPE geomrežama, čavlanje i potporni zid u dužini 20 m. Visina konstrukcije iznosi 10 m. Pri proračunu za izradu armiranog tla I čavlanja primijenjeni su AASHTO standardi, a potporni zid je proračunat u skladu sa EN 1997-I normama. Sve metode su implementirane u software-ski paket Plaxis koji je korišten za istraživanje. Na osnovu provedenih analiza izvršen je izbor rješenja kao najpovoljnijeg.

Professional paper

SUMMARY The paper describes analyses solution of cut in the highway. There have been used three methods of making construction: reinforced wall with HDPE geogrids, soil nailing and retaining wall 20 meters long. AASHTO standards have been used for checking stability of reinforced wall and soil nailing, while retaining wall is based on EN 1997-I standards. All of these methods are implemented in software package Plaxis which is used for exploration. The best solution is chosen by these analyses.

1. UVOD Analizom je potrebno utvrditi rješenje za dati problem. Kosina usjeka na autocesti je heterogeno tlo koje se sastoji od 3 sloja, a geotehničke sredine imaju sljedeće karakteristike:

1. INTRODUCTION This analysis has to give a solution for a slope insurance. A slope cut, which is on highway, is a heterogeneous soil and it is made of three layers, so in geotechnical way they have these characteristics:

Tabela 1. Karakteristike geotehničkih sredina Table 1. Characteristics of geotechnical parts

Parametar - Parameter Pokrivač Blanket

Raslabljen substrat Strengthened

substrate

Substrat lapor Substrate

lactose visina - height [m] 3,0 4,5 3,65 specifična zapreminska težina [kN/m3] specific volume weight [kN/m3] 18,0 19,0 21,0

kohezija - cohesion [kPa] 10,0 17,0 60,0 ugao unutrašnjeg trenja [o] angle of inner friction 23 26 30

Referentni Young-ov modul [kPa] Reference Young's Module [kPa] 12 000 25 000 80 000

Poisson-ov koeficijent [-] Poisson coefficient [-] 0,3 0,3 0,3


204

Rješenje je moguće izvesti u tri slučaja, kao potporna konstrukcija od armiranog tla, čavlanjem ili izradom jednostavnog potpornog zida. 2. PRORAČUN POTPORNE

KONSTRUKCIJE 2.1. Proračun potpornih konstrukcija od

armiranog tla Kod zidova armiranog tla potrebno je provjeriti vanjsku i unutrašnju stabilnost. Vanjska stabilnost uključuje dokaze otpornosti na: a) prevrtanje, b) klizanje, c) slom temeljnog tla, d) globalnu stabilnost, koja armiranu zonu zida tretira kao kvazi-homogeni kruti blok.

Solution is possible to make in three ways: with methods of reinforced wall, soil nailing or by making a simple retaining wall. 2. CALCULATION OF SUPPORT

CONSTRUCTION 2.1. Calculation of support constructions with

reinforced wall Reinforced walls have to satisfy analyses of internal and external stability. External stability includes proves capacity of: a) overturning (eccentricity) b) sliding c) bearing capacity d) deep seated stability (rotatonial; global stability), which reinforced zone of walls threates as quasi – homogenous stiff block

a) b) c) d) Slika 1. Principi gubitka stabilnosti zida uslijed gubitka nosivosti na: a) prevrtanje, b) klizanje, c)

slom temeljnog tla, d) globalni slom [4] Figure 1. Principles of wall failure due to loss capacity of: a) overtuning, b) sliding, c)bearing

capacity, d) global stability [4]

Svi proračuni trebaju zadovoljiti minimalne faktore sigurnosti koji su predstavljeni u Tabeli 2:

All of the calculations need to satisfy minimal factors of stability for external stability that are presented in Table 2:

Tabela 2. Zahtjevi minimalnih faktora sigurnosti vanjske stabilnosti potporne konstrukcije od armiranog tla [4] Table 2. Required minimum factors of safety for external stability of reinforced wall [4]

Vanjska stabilnost - External Stability Klizanje - Sliding F.S. ≥ 1.5 (MSEW); 1.3 (RSS) Ekscentričnost u bazi - Eccentricity e, at Base ≤ L/6 in soil L/4 in rock Kapacitet ležaja - Bearing Capacity F.S. ≥ 2.5 Globalna stabilnost - Deep Seated Stability F.S. ≥ 1.3 Stabilnost spoja - Compound Stability F.S. ≥ 1.3 Seizmička stabilnost - Seismic Stability F.S. ≥ 75% of static F.S. (All failure modes)

Unutrašnja stabilnost podrazumijeva provjeru napona u zatežućim elementima, tj. mogućnost čupanja ili prekida zatežućih elemenata. “Unutarnja stabilnost “aktivne” zone zida koja je od “pasivne” zone razgraničena linijom koja povezuje lokacije maksimalnih vlačnih sila u svakoj razini armature.

Internal stability includes checking stresses in tensiled elements that means pullout resistance of tensiled elements. “Internal stability of “active” zone of wall that is divided from passive through line that connects locations of maximum values of tensile strength on every level of reinforcement.


205

Položaj maksimalne vlačne sile uzduž armature utvrđen je eksperimentalnim istraživanjem velikog broja zidova stvarne veličine i razlikuje se za različite krutosti armature (Elias i dr., 1997).” [7] Kao geosintetičko ojačanje pri proračunu i analizi izabrana je, kao najčešće korištena, HDPE mreža maksimalne nosivosti 250 kN/m’ i ukupne dužine 6,5m. Izabrana mreža ispunjava sve zahtjeve nosivosti i kao takva predstavlja idealan izbor za ojačanje konstrukcije. 2.2. Proračun potporne konstrukcije

čavlanjem Prilikom proračuna zidova ojačanih čavlima potrebno je ispitati vanjsku I unutrašnju stabilnost te stabilnost podloge (primarna I sekundarna obloga). Potrebne analize za dokaz nosivosti provedene su u ovoj analizi pri izradi rješenja zaštite kosine čavlanjem tla te su zadovoljeni minimalni uslovi faktora sigurnosti (Tabela 3).

The position of maximum value of tensile strength in reinforcement is set by many experimental exploring many real sized walls and it is different for every type rigidity of reinforcements (Elias and others, 1997).” [7] In calculations and analysis, as a geosynthetic reinforcement it has been chosen, as mostly used, HDPE geogrid with maximum strength of 250 kN/m’ and in total length of 6,5 m. This chosen grid satisfies every requests of capacity and so it presents ideal choice for reinforced construction. 2.2. Calculation support construction of soil

nail walls By calculation of soil nail walls there is some stabilitiy that need to be checked and it includes external and internal stability so as the stability of support (permanent and temporaty facing). All of these analyses has been checked in this paper and all of the minimum factors of safety are achieved (Table 3).

Tabela 3. Minimalni preporučeni faktori sigurnosti za dimenzioniranje čavlanog tla [5] Table 3. Minimum recommended factors of safety for soil nail walls

Failure mode Resisting component Symbol

Minimum Recommended Factors of Safety Static Loads Seismic Loads

(Temporaty and Permanent

Structures)

Temporary Structure

Permanent Structure

External Stability

Global Stability (long term) FSG 1,35 1,5 1,1

Global Stability (excavation) FSG 1,2 - 1,3 NA

Sliding FSSL 1,3 1,5 1,1 Bearing Capacity FSH 2,5 3,0 2,3

Internal Stability

Pullout Resistance FSP 2,0 1,5 Nail Bar Tensile

Strength FST 1,8 1,35

Facing Strength

Facing Flexure FSFF 1,35 1,5 1,1 Facing Punching

Shear FSFP 1,35 1,5 1,1

H.-Stud Tensile (A307 Bolt) FSHT 1,8 2,0 1,5

H.-Stud Tensile (A325 Bolt) FSHT 1,5 1,7 1,3

2.3. Proračun potpornih zidova Dokaz stabilnosti potpornih zidova se odnosi na statički proračun kojima dokazujemo da su naponi u karakterističnim presjecima na tlo ispod temelja u dopuštenim granicama, te da je zid stabilan na klizanje I prevrtanje.

2.3. Callculation of retaining wall A proof of stability for retaining walls is based on static calculation what serves for proving that the stresses in characteristic sections on soil under base are in allowed limits and that a wall has capacity on sliding and overtuning.


206

Proračun se vodi iterativno. Prvo se pretpostave dimenzije, provjere naponi I nakon toga se izvrši potrebna korekcija dužina. Sve analize za dokaz sigurnosti potpornih zidova provedene su u ovom radu te su ispunjeni minimalni zahtjevi faktora sigurnosti. 3. REZULTATI I ANALIZA Primjenom software-a Plaxis 8.6 provedeni su proračuni rješenja zaštite kosine zasjeka: armirano tlo, čavlanje i potporni zid. Dobijene su različite vrijednosti vertikalnih, horizontalnih pomijeranja, efektivnih napona i sl. pa je izabrano najpovoljnije odnosno najsigurnije rješenje. 3.1. Globalna sigurnost Globalna stabilnost kao jedan od osnovnih uslova nije zadovoljen kod proračuna čavlanog tla. Armirano tlo i betonski potporni zid ispunili su uslov globalne stabilnosti gdje je faktor stabilnosti FS≥1,3. 3.2. Pomijeranja Slika 2. prikazuje totalna pomijeranja proračunatih rješenja zaštite kosine. Na Slici 2.a su totalna pomijeranja tla iza lica zida armiranog tla (38,86*10-3 m), na Slici 2.b totalna pomijeranja tla iza obloge čavlanog tla (248,78*10-3 m) a Slika 2.c prikazuje totalna pomijeranja tla iz betonskog potpornog zida (75,78*10-3 m). Na Slici 3. su predstavljena horizontalna pomijeranja tla sa maksimalnim vrijednostima na vrhu: Slika 3.a - armirano tlo (23,34*10-3 m), Slika 3.b - čavlano tlo (222,54*10-3 m) i Slika 3.c - betonski potporni zid (21,71*10-3 m). Vertikalna pomijeranja tla su prikazana na Slici 4: Slika 4.a – armirano tlo (33,71x10-3 m), Slika 4.b – čavlano tlo (161,67x10-3 m) i Slika 4.c – betonski potporni zid (75,78x10-3 m).

The process of calculation is iterative. First of all dimensions are assumed, the stresses are checked and after that the correction of dimensions are implemented. All of the analyses for proof of safety for retaining wall have been done and the requirements of minimum factor of safety are satisfied. 3. RESULTS AND ANALYSIS For the calculations of slope insurance, which includes: reinforced wall, soil nailing and retaining wall, there has been used a software called Plaxis 8.6. There are different results and values for vertical, horizontal displacements, effective stresses and based on that the safest solution is chosen. 3.1. Global safety As the one of the main requirement, the global stability is not reached for soil nail wall. Reinforced wall and concrete retatining wall have reached the requirement of global stability where FS ≥ 1,3. 3.2. Displacements In Figure 2. are shown total displacements for all solutions. Figure 2.a shows total displacements of soil behind the face of reinforced wall (38,86*10-3 m), Figure 2.b shows total displacements of soil behind facing of soil nail wall (248,78*10-3 m) and Figure 2.c shows total displacements of soil behind concrete retaining wall (75,78*10-3 m). In Figure 3. are shown horizontal displacements of soil with maximal values on the top. Figure 3.a – reinforced wall (23,34x10-3 m), Figure 3.b – soil nail wall (222,54x10-3 m) i Figure 3.c – concrete retaining wall (21,71x10-3 m). Vertical displacements of soil are shown in Figure 4: Figure 4.a – reinforced wall (33,71x10-3 m), Figure 4.b – soil nail wall (161,67x10-3 m) i Figure 4.c – concrete retaining wall (75,78x10-3 m).

a)


207

Slika 2. Totalna pomijeranja tla iza lica zida

Figure 2. Total displacements of soil behind the wall face

b)

c)

a)

b)


208

Slika 3. Horizontalna pomijeranja tla iza lica zida Figure 3. Horizontal displacements of soil behind the wall face

Slika 4. Vertikalna pomijeranja tla iza lica zida

Figure 4. Vertical displacements of soil behind the wall face

c)

a)

b)

c)


209

3.3. Efektivni naponi Maksimalne vrijednosti efektivnih napona tla locirane na dnu (temeljnoj stopi) zida prikazane su na Slici 5: Slika 5.a – armirano tlo (466,09 kN/m2), Slika 5.b – čavlano tlo (220,19 kN/m2) i Slika 5.c - betonski potporni zid (237,64 kN/m2).

3.3. Effective stresses Maximal values of effective stresses in soil located on the bottom (base foot) of wall as shown in Figure 5: Figure 5.a – reinforced wall (466,09 kN/m2), Figure 5.b – soil nail wall (220,19 kN/m2) i Figure 5.c – concrete retaining wall (237,64 kN/m2).

Slika 5. Efektivni naponi

Figure 5. Effective stresses 3.4. Horizontalna pomijeranja lica zida Horizontalna pomijeranja lica zida prikazana su na Slici 6.: Slika 6.a – armirano tlo (-23,34x10-3 m), Slika 6.b - čavlano tlo (-217,14x10-3 m) i Slika 6.c – betonski potporni zid (-12,15x10-3 m).

3.4. Horizontal displacements of wall face Horizontal displacements of wall face are shown in Figure 6.: Figure 6.a – reinforced wall (-23,34x10-3 m), Figure 6.b – soil nail wall (-217,14x10-3 m) i Figure 6.c – concrete retaining wall (-12,15x10-3 m).

a)

b)

c)


210

a) b) c)

Slika 6. Horizontalna pomijeranja lica zida Figure 6. Horizontal displacements of wall face

3.5. Vertikalna pomijeranja stope (armirano tlo i čavlanje) Kao maksimalna vertikalna pomijeranja stope potpornog zida od armiranog tla i betonskog potpornog zida očitane su vrijednosti i prikazane na Slici 7.: Slika 7.a – armirano tlo (-6,87*10-3 m) i Slika 7.b – betonski potporni zid (-37,24*10-3 m).

3.5. Vertical displacements of foot (reinforced and soil nail wall) As maximal vertical displacements on foot of support construction with reinforced and concrete retaining wall there are values presented in Figure 7.: Figure 7.a – reinforced wall (-6,87*10-3 m) i Figure 7.b – concrete retaining wall (-37,24*10-3 m).

a) b)

Slika 7. Vertikalna pomijeranja stope Figure 7. Vertical displacements of foot

4. ZAKLJUČAK Na osnovu odrađenih proračuna i analize globalne sigurnosti, za rješenje zaštite ove kosine izabrana je metoda armiranog tla. Metoda čavlanja tla u programu Plaxis nije zadovoljila faktor sigurnosti FS≥1,3 te je zbog toga kao potencijalno rješenje odbacujemo.

4. CONCLUSION Based on calculated results and analasys of global stability, as a best solution for a slope insurance a method of reinforced wall is chosen. A method of soil nailing has not satisfied factors of safety in software Plaxis (FS≥1,3), and for that it is rejected as a potential solution, ž


211

Potporni zid je zadovoljio faktor globalne sigurnosti međutim pokazuje velika totalna i vertikalna pomijeranja tla iza lica zida kao i vertikalna pomijeranja stope. Prednosti armiranog tla u odnosu na betonski potporni zid je prvenstveno veći faktor sigurnosti. Potporna konstrukcija je visne 10 m za koju se uglavnom ne izvode betonski potporni zidovi koji su masivni. Izrada potporne konstrukcije od armiranog tla predstavlja bržu i jeftiniju varijantu koja je pri tome tehnički izvodiva i za visine veće od 25 m, stoga je u ovom slučaju biramo kao rješenje problema.

Retaining wall has satisfied a minimum factor of global safety, but it has great total and vertical displacements of soil behind the wall face so as vertical displacements of foot base. The adventages of reinforced wall in regards to concrete retaining wall are firstly of all the greater factor of safety. A support construction is 10 m height and for these constructions concrete retaining walls are not used as a massive ones. Support construction with reinforced wall presents faster and cheaper method which is technically used for heights and above 25 m, so in this case it is chosen as a solution of a problem.

5. REFERENCES – LITERATURA [1] Brooks H., Nielsen J.P., Basic of Retaining

Wall Design 10th Edition, A Design Guide for Earth Retaining Structures, HBA PUBLICATIONS

[2] Ćorić S., dipl.građ.inž. (2008), Geostatički proračuni (Treće izdanje), Univerzitet u Beogradu – Rudarsko – geološki fakultet, Časopis „Izgradnja“, Saveza građevinskih inženjera i tehničara Srbije i Saveza arhitekata Srbije, Beograd

[3] Dean M. White, P.E. (2010), Engineering Design Manual for Stoneterra Wall System 1st Edition

[4] Elias V., P.E; Christopher B. R., Ph.D., P.E. and Berg R. R., P.E. (2001), Mechanically Stabilized Earth Walls and Reinforced Soil Slopes Design and Construction Guidelines, National Highway Institute, Federal Highway Administration, U.S. Department of Transportation, Washington, D.C.

[5] Lazarte C. A., Ph.D., P.E., Elias V., P.E., Espinoza R. D., Ph.D., P.E., Sabatini P. J., Ph.D., P.E. (2003), Geotechnical Engineering Circular No. 7 Soil Nail Walls, Office of Technology Application, Office of Engineering/Bridge Division, Federal Highway Administration, U.S. Department of Transportation, 400 Seventh Street, S.W., Washington, D.C. 20590

[6] Prof.dr. Mustafa Selimović, dipl.ing.građ. (2000), Mehanika tla i temeljenje, Dio I Mehanika tla, Univerzitet „Džemal Bijedić“ Mostar, Građevinski fakultet, Mostar

[7] Skejić Adis (2017), Numeričko modeliranje utjecaja interakcije armature I nekoherentnog zasipa u proračunu

stabilnosti zidova od armiranog tla, Doktorski rad, Sveučilište u Zagrebu, Građevinski fakultet, Zagreb

[8] Smjernice za projektovanje, građenje, održavanje i nadzor na putevima; Knjiga I: Projektovanje, Dio 3: Projektovanje konstrukcija na putevima; Projektantska smjernica (PS 1.3.3); Poglavlje 3: Gravitacioni potporni zidovi; RS – FBIH&H/3CS – DDC 433/94

[9] Suljić N., dipl.ing.građ. (2005), Savremeni materijali za izvođenje potpornih konstrukcija, Izdavačko – grafička kuća Planjax, Bobare 22 – Tešanj

[10] Suljić N., dipl.ing.građ. (2010), Potporne konstrukcije, Rudarsko – geološko – građevinski fakultet Univerziteta u Tuzli, Tuzla

[11] Sun C., Ph.D., P.E. and Graves C., Ph.D., P.E., P.G. (2013), Mechanically Stabilized Earth (MSE) Walls Design Guidance, University of Kentucky Transportation Center

[12] Szavits – Nossan A. & Ivšić T., 2006, Novi Eurokod 7: geotehničko pojektiranje, Građevinski fakultet Sveučilišta u Zagrebu, Kačićeva 26, 10000 Zagreb

[13] Talić Z. (2014), Odabrana poglavlja mehanike tla, Politehnički fakultet Univerziteta u Zenici, Fakultetska br. 1, Zenica

Coresponding author: Nejra Turčinović University of Zenica, Polytechnic Faculty Fakultetska 1 72000 Zenica e-mail: [email protected] tel.: +387 62 152849


212

Mašinstvo 4(14), 213 – 226, (2017) S. Brdarević et all: ANALYSIS OF THE ATTRACTIVENESS…

213

ANALIZA ATRAKTIVNOSTI STUDIJA NAUKE I TEHNOLOGIJE

ANALYSIS OF THE ATTRACTIVENESS OF SCIENCE AND TECHNOLOGY STUDIES

Brdarević Safet1 Arnaut Dino2 1University of Zenica, Faculty for Mechanical Engineering 2University of Zenica, Faculty of Economics Ključne riječi: obrazovanje, nauka i tehnologija, opadanje interesa, Bosna i Hercegovina Keywords: education, science and technology, declining interest, Bosnia and Herzegovina. Paper received: 22.08.2017. Paper accepted: 16.11.2017.

Originalan naučni rad REZIME U mnogim zemljama postoji zabrinutost da upis u tehničke i naučne profesije opada i da je potrebno više studenata usmjeriti i zainteresirati za karijeru u nauci i tehnologiji. Uzrok za studente da ne biraju studije u nauci i tehnologiji obično se ne tiču sposobnosti samih studenata, već su više vezane za studentsku percepciju i stav o atraktivnosti predmeta vezanih za nauku i tehnologiju. Interes za studije nauke i tehnologije postaje važno pitanje s obzirom da sve više radnih mjesta u oblasti nauke i tehnologije ostaje neupražnjeno, a i tehnološki trendovi stvaraju iz godine u godinu potrebu za novim kadrovima iz naučno-tehnoloških disciplina. Brojne studije pokazuju da interesovanje za nauku i tehnologiju opada s školskim godinama. Stoga, podizanje pozitivnih stavova, motivacije i interesa za naučne i tehnološke predmete postaje ključno pitanje. Ovaj rad analizira broj upisanih studenata u Federaciji Bosne i Hercegovine za period od 2009. do 2017. godine. Iz analize zaključujemo da su među najpopularnijim studijima studiji društvenih i humanističkih nauka sa jakim porastom popularnosti zdravstvenih studija, dok studiji vezani za prirodne nauke i tehnologiju još nisu stekli željenu popularnost. Svrha ovog istraživanja je podizanje svijesti o zanemarivanju podsticanja studija iz oblasti tehničkih nauka. Stoga, ovo istraživanje predstavlja uvod za buduća istraživanja o atraktivnosti studija tehničkih nauka.

Original scientific paper

SUMMARY In many countries, there is concern that enrolment in science and technology professions is decreasing and that more students need to be directed and interested in a career in science and technology. The reason why students do not choose science and technology studies is usually not about their abilities, but it is more related to student perceptions and attitudes about the attractiveness of subjects related to science and technology. Interest in science and technology studies is becoming an important issue given that more and more jobs in the field of science and technology remain empty, and technological trends create the need for new staff from science and technology disciplines every year. Numerous studies have shown that interest in science and technology has been declining with school years. Therefore, raising positive attitudes, motivation and interest in scientific and technological subjects becomes a key problem. This paper analyses the number of enrolled students in the Federation of Bosnia and Herzegovina for the period from 2009 to 2017. From the analysis, we conclude that among the most popular studies are the those of social and humanistic sciences with a strong increase in the popularity of health studies, while studies related to natural sciences and technology have not yet gained the desired popularity. The aim of this research is to raise awareness of the neglect of encouraging studies in the field of technical sciences. Therefore, this research represents an introduction for future research on the attractiveness of technical studies.


214

1. UVOD Od djetinjstva do adolescencije oni sa višim stepenom akademske motivacije su ujedno i više kompetentni u školi, dokazujući znatno veće akademsko postignuće, pozitivnije percepcije njihove akademske kompetencije, kao i niže akademske anksioznosti i manje ekstrinzične motivacije (Gottfried et al., 2009:729). Istraživanje ukupnih efekata pokazalo je važne uticaje akademskog vremena, stava i motivacije na postignuće. Od primarnog značaja je dokaz snažnih efekata motivacije, pozitivnog odnosa i angažovanja u akademskom radu za uspeh u matematici i nauci (Singh et al., 2002:330). Prema Panu, dobro je utvrđeno i utemeljeno da je motivacija ključna za predviđanje akademskog postignuća studenta, te je istraživanje pokazalo da u poređenju sa sposobnošću (npr. ACT/SAT rezultati i IQ), akademska motivacija je bolji prediktor uspjeha učenja studenata (Pan i Gauvain 2012:92). Drugi autori su pokazali da je motivacija ključna za postizanje i samoostvarivanje (Cavas, 2011:31). Također, došlo je do shvatanja da stav igra važnu ulogu u namjeri da se nastave studije u domenu prirodnih nauka. U istraživanima provedenim u SADu i Australiji, pokazano je da su stavovi prema naučnim časovima najbolji prediktori namjera učenika da se upišu studije nauke (Reid i Skryabina 2002:69). Stoga i smatramo da bi evolucija individualnih interesa, stavova i motivacija trebala biti dodatno ispitana, jer ukazuje na povezanost istih sa odabirom studije budućih studenata. Barmby i saradnici (2008.) su ustanovili u svom istraživanju o padu stavova, koje je obuhvatilo publikacije od 1975. do 2006. godine, pronašli petnaest studija koje su zabilježile pad na sekundarnom a samo jednu koja nije zabilježila nikakva vid promjene, kao i četiri studije koje su ustanovile pad na osnovnom nivou obrazovanja u odnosu na četiri koje nisu ustanovila nikakve promjene. Gottfried i saradnici (2009) su analizirajući sedam novijih studija ustanovili da su matematika i nauka posebno zabrinjavajući. Pad značajnih konstrukata interesa, kao što su motivacija i stav, sa godinama često je razmatran i obrađen u literaturi o edukaciji o nauci. Osborne i saradnici (2003) su iznijeli je vrlo interesantnu sintezu u kojoj su identifikovali devet značajnih studija objavljenih između 1976.

1. INTRODUCTION From childhood to adolescence, those with a higher degree of academic motivation are also more competent at school, proving significantly higher academic achievement, more positive perceptions of their academic competence, and lower academic anxiety and less extrinsic motivation (Gottfried et al., 2009: 729). The study of overall effects has shown the important impacts of academic time, attitude and motivation on achievement. Of primary importance is the evidence of the powerful effects of motivation, positive attitudes and engagement in academic work for success in mathematics and science (Singh et al., 2002: 330). According to the Pan, it is well established that the motivation is the key to predicting the academic achievement of the student, and the research showed that compared to the ability (e.g. ACT/SAT results and IQ) academic motivation is a better predictor of student learning success (Pan and Gauvain 2012: 92). Other authors have shown that motivation is crucial for achievement and self-development (Cavas, 2011: 31). It came to the understanding that attitude plays an important role in the intent to continue studies in the field of natural sciences. In research conducted in the United States and Australia, it has been shown that attitudes toward scientific lessons are the best predictors of students' intentions to enrol in science studies (Reid and Skryabina 2002: 69). Therefore, we believe that the evolution of individual interests, attitudes and motivations should be further tested as it points to the connection between them with the choice of a study of future students. Barmby et al. (2008) found in their research on the decline in attitudes, which included publications from 1975 to 2006, fifteen studies that recorded a decline on the secondary one and only one that did not record any kind of change, as well as four studies that have found a drop in the basic level of education compared to four who have not found any changes. Gottfried et al (2009) analysing seven new studies found that mathematics and science are particularly troubling. The decline in significant constructs of interest, such as motivation and attitude, with years is often considered and addressed in the science education literature. Osborne et al. (2003) presented a very interesting synthesis identifying nine significant studies published between 1976


215

i 2001. godine, koje su ukazivale na smanjenje stavova studenata od 11 godina i više. Svih devet studija pokazuju kako se interesovanje djece i stav prema nauci opadaju prelaskom u srednju školu. Također, Venturini (2004) je u svojoj mreži istraživanja došao do istog zaključka, navodeći i analizirajući zasebnih sedam studija.

and 2001, which indicated a decline in students' attitudes of eleven years old or more. All nine studies show that the interest of children and attitudes toward science is decreasing by moving to secondary school. Also, Venturini (2004) came to the same conclusion in his research network, citing and analysing separate seven studies.

Tabela 1. Istraživački članci koji su zabilježili pad interesovanja, motivacije, stavova ili entuzijazma za nauku i tehnologiju1 Table 1. Research articles that recorded a decline in interest, motivation, attitudes or enthusiasm for science and technology2

Novije istraživanje i pregled literature i studija vezanih za zainteresiranost ka studijama prirodnih nauka i tehnologije dato je od strane Potvina i Hasnija (2014) koji su analizirali literaturu od 2000. godine pa nadalje.

1 Izvor: Adaptirano prema istraživanju Potvina i Hasnija (2014) 2 Source: Adapted from Potvin and Hasni (2014)

Recent research and review of literature and studies related to the interest in science and technology studies was given by Potvin and Hasni (2014) who analysed literature from year 2000 onwards.

4 5 6 7 8 9 10 11 12 13 14 15 16 +

O 1 2 3 4 5 6 7 8 9 10 11 +

Referenca Zemlja Varijable Uzorak (N) Protokl

Turner i Ireson (2014)

UKStav i

entuzijazam15 Longitudinalni S ↘ ↕

Alexander et al. (2012)

SAD Interes 192 Longitudinalni S ↘ ↘ ↘

Cavas (2011) Turska Motivacija 376 Transverzalni S ↘ ↘Hong i Lin(2011)

Tajvan Interes i stav 2876 Transverzalni S ↘ ↕

Kirikkaya (2011) Turska Entuzijazam 540 Transverzalni S ↘ ↕ ↘ ↘Vedder-Weiss iFortus (2011)

Izrael Stav 1181 Transverzalni S ↘ ↘ ↕Guvercin et al.(2010)

Turska Motivacija 2231 Transverzalni S ↘Francis i Greer(2001)

UK Stav 1534 Transverzalni S ↘ ↘Bennett i Hogarth (2009)

UK Stav 280 Transverzalni S ↘ ↕

Cheung (2007) Hong Kong Stav 954 Transverzalni S ↘ ↘Devetak et al.(2009)

Slovenija Motivacija 191 Transverzalni S ↘Gottfried et al.(2009)

SAD Motivacija 130 Longitudinalni S ↘ ↘ ↘ ↘Barmby et al.(2008)

UK Stav 932 Transverzalni S ↘ ↘

Hassan (2008) AustralijaStav i

motivacija1745 Transverzalni S ↗ ↕

Logan i Skamp(2008)

Australija Stav i interes 20 Longitudinalni S ↕Owen et al.(2008)

UK Stav i interes 1288 Transverzalni S ↘ ↘ ↘ ↘

Sorge (2007) SAD Stav 1008 Transverzalni S ↘ ↘ ↘ ↕ ↘Murphy et al.(2006)

UK i Oman Stav 1923 Transverzalni S ↘George (2000; 2006)

SAD Stav 444 Longitudinalni S ↘ ↘ ↕ ↘Reid i Skryabina (2002)

Škotska Stav 850 Transverzalni S S ↘ ↕ ↗ ↘

Pell i Jarvis (2001) UKStav i

entuzijazam800 Transverzalni S ↘ ↘ ↘ ↘ ↘

Godine

Školska godina


216

Analizirana literatura obuhvata 21 ERIC-indeksiran3 članak na temu pada zainteresiranosti za studije prirodnih nauka i tehnologija. U tabeli 1. prikazan je pregled navedenih članak prema godinama njihove publikacije. Tabela sadrži podatke o autorima, mjestu porijekla podataka, proučavanim i korištenim varijablama, ukupnom broju uzorka, kao i o vrsti korištenog protokola. Transverzalni protokol promatra različite učenike iz različitih školskih godina, dok longitudinalni promatra iste učenike koji su praćeni tokom dužeg vremenskog perioda (Potvin i Hasnij, 2014). Slovo S označava najnižu školsku godinu kada je ispitivanje započelo, crvena strelica ka dolje označava značajan pad u odnosu na prethodni zabilježeni nivo, dok zelena strelica ka gore označava porast. Siva strelica okrenuta ka gore i dolje pokazuje da nisu zabilježene veće ili značajnije varijacija. Iz tabele se jasno vidi da postoji konstanta tendencija pada interesovanja, motivacije, stavova i entuzijazma za nauku i tehnologiju. Tragično, čini se da škola nije učinila ništa za svoje učenike u smislu podsticanja njihovog interesovanja za nauku. Zapravo, navedeni podaci nam ne pokazuju poboljšanje stava prema nauci kod učenika od 9 godina pa više što dovodi do spekulacija da upravo školsko educiranje učenika o nauci čini više štete nego dobra (Osborne et al., 2003). Objašnjenje navedene situacije nastoje objasniti mnogi istraživači. Barmbi (2008) tvrdi da se nauka koja se proučava u školi ne percipira kao praktična iako je dobro objašnjena ili relevantna. Krapp (2011:35) objašnjava navedeni pad pretpostavkom da razvoj naučnog interesa prvenstveno zavisi od kvaliteta i vrste instrukcija. 2. NAKLONOST PREMA NAUCI I

TEHNOLOGIJI Studenti uglavnom ne vole da studiraju prirodne nauke i tehnologiju. Različita istraživanje stavova studenata prema nauci i tehnologiji potvrđuju ovakav negativan stav prema nauci. Takav vid negativnosti naročito dolazi do izražaja kod starijih studenata, tj. odbojnost ka nauci i tehnologiji raste sa starenjem studenata. 3 ERIC (Educational Resources Information Center) je najčešće korišten indeks vezan za literaturu o obrazovanju (https://eric.ed.gov/).

The analysed literature includes 21 ERIC-indexed4 articles on the topic of falling interest in natural science and technology studies. Table 1 shows the review of the articles listed by the years of their publication. The table contains information about authors, place of origin of the data, studied and used variables, the total number of samples, and the type of protocol used. The transversal protocol examines different students from different school years, while longitudinal observes the same students who have been followed for a long period of time (Potvin and Hasni, 2014). The letter S indicates the lowest school year when the test started, the red arrow down indicates a significant drop in relation to the previous recorded level, while the green arrow up indicates an increase. The grey arrow facing up and down shows that no significant variations have been recorded. The table clearly shows that there is a constant tendency of falling interest, motivation, attitudes and enthusiasm for science and technology. Tragically, it seems that the school did not do anything for its students in terms of encouraging their interest in science. In fact, the given data does not show us the improvement of the attitude towards science in the students of 9 years old and up, which leads to speculation that school education of students about science is more damaging than good (Osborne et al., 2003). Many researchers are trying to explain the situation. Barmbi (2008) argues that science studied at school is not perceived as practical, although it is well explained or relevant. Krapp (2011:35) explains the above with assumption that the development of a scientific interest primarily depends on the quality and type of instructions. 2. AFFECTION FOR SCIENCE AND

TECHNOLOGY Students generally do not like to study natural sciences and technology. Different researches of student attitudes towards science and technology confirmed this negative attitude towards science. This type of negativity is especially evident in older students, i.e. aversion towards science and technology is growing with the aging of students.

4 ERIC (Educational Resources Information Centre) is the most widely used index on education literature (https://eric.ed.gov/).


217

Stoga, većina istraživača i predlaže da se pozitivan stav i interes ka nauci i tehnologiji krene da razvija već kod učenika u ranom dobu. Istraživanje od strane Osborna i saradnika (2009) pokazuje da su stavovi studenata prema nauci i tehnologiji formirani u dobu između 10. i 14. godine, te ukazuju na to da u 14. godini su stvoreni oformljeni stavovi učenika, što u velikoj mjeri utječe na njihov budući izbor karijere. Također, žene nisu dovoljno zastupljene u profesijama nauke i tehnologije (Osborne et al., 2003 i Hill et al., 2010), ali ova nejednakost nije izazvana nemogućnošću savladavanja ovih profesija od strane djevojčica, ali jest rezultat izbora djevojčica tokom njihove školske karijere (Hill et al., 2010). Stepen postignuća djevojčica je sličnom nivou postignuća dječaka (OECD, 2006 i Elwood i Comber, 1996), ali, za razliku od dječaka, djevojčice imaju veću zastupljenost negativnih stavova prema nauci i tehnologiji (Kind et al., 2007 i Osborne et al., 2003). Problem stvaranja pozitivnog stava ka nauci nalazimo i iz istraživanja koje dokazuje da nastavnici osnovnih škola ocjenjuju nauku među najgorim i najmanje zanimljivim predmetom za podučavanje (Wilkins, 2010). Stoga, nije ni čudna činjenica da se nastavnici razlikuju u stepenu pokazivanja entuzijazma dok predaju predmete vezane za nauku i tehnologiju (Trumper, 1998 i Palmer, 2004). Nastavnici su ti koji mogu utjecati na iskustva učenika kroz svoje sposobnosti da sasvim slučajno ili pak namjerno ugrade vrijednosti i uvjerenja u svoje učenje, da bi učenici mogli prihvatiti te vrijednosti i vjerovanja kao svoje stavove (Frenzel et al., 2009). Takvi stavovi prema nastavi nauke i tehnologije su najčešće povezani sa relativno niskim osjećanjima kompetentnosti kao i niskim nivoima samo-efikasnosti nastavnika u nastavi nauke i tehnologije (Beilock et al., 2010). To predstavlja problem, s obzirom da upravo škole igraju glavnu ulogu u razvoju pozitivnih stavova učenika ka određenim predmetima i profesijama (Davis, 2003). Teorije društvenog kognitivnog učenja nam dokazuju da djeca uče promatrajući ponašanja svojih nastavnika, te na taj način oblikuju svoje stavove prema predmetu slušajući komentare nastavnika i promatrajući uživanje svojih učitelja dok predaju određenu temu (Frenzel et al., 2009). Pored toga, nastavnici koji nemaju sposobnosti, entuzijazam i samopouzdanje imaju visok stepen vjerovatnosti da njihovi učenici budu učenici sa lošim stavovima (Osborne i Simon, 1996).

Therefore, most researchers suggest that positive attitude towards science and technology needs to develop already at students early age. The research by Osborne et al. (2009) shows that students' attitudes toward science and technology have been formed between the ages of 10 and 14, indicating that at the age of 14, student attitudes were created, which greatly affected their future career choice. Also, women are not sufficiently represented in the professions of science and technology (Osborne et al., 2003 and Hill et al., 2010), but this inequality is not caused by the inability to overcome these professions by girls, but is the result of the selection of girls during their school career (Hill et al., 2010). The level of achievement of girls is similar to the level of achievement of boys (OECD, 2006 and Elwood and Comber, 1996), but, unlike boys, girls have a higher proportion of negative attitudes toward science and technology (Kind et al., 2007 and Osborne et al., 2007) 2003). The problem of creating a positive attitude towards science is also found in research that proves that teachers of elementary school’s rate science among the worst and least interesting subject of instruction (Wilkins, 2010). Therefore, it's no wonder that teachers differ in the degree of enthusiasm while teaching subjects related to science and technology (Trumper, 1998 and Palmer, 2004). Teachers are those who can influence students' experiences through their ability to accidentally or intentionally integrate values and beliefs into their own teaching so students can accept these values and beliefs as their attitudes (Frenzel et al., 2009). Such attitudes towards teaching science and technology are most often associated with relatively low feelings of competence as well as low levels of self-efficacy of teachers in teaching science and technology (Beilock et al., 2010). This is a problem, since schools play a major role in the development of students' positive attitudes towards certain subjects and professions (Davis, 2003). Theories of social cognitive learning show that children learn by observing the behaviour of their teachers, thus forming their attitudes toward the subject by listening to teachers' comments and observing the enjoyment of their teachers while teaching a subject (Frenzel et al., 2009). In addition, teachers who lack capabilities, enthusiasm, and self-confidence have a high degree of probability that their students become students with poor attitudes (Osborne and Simon, 1996).


218

Stoga je ključno da imamo pozitivan stav učitelja, nastavnika i profesora prema nauci i tehnologiji da bi omogućili razvoj pozitivnih stavova učenika i studenata. Analizom broja upisanih studenata u Federaciji Bosne i Hercegovine (tabela 2) za period od 2009. do 2017. godine, isključujući upis 2015. godine zbog nedostupnosti adekvatnih podataka, vidimo da je ukupni broj studenata koji su se upisali opada od 2013. godine. U kumulativnom poređenju upisanih u navedenom periodu uočavamo da su među najpopularnijim studijima studiji društvenih i humanističkih nauka sa jakim porastom popularnosti zdravstvenih studija (slika 1).

Therefore, it is crucial that we have a positive attitude of teachers and professors to science and technology in order to enable the development of positive attitudes of students. By analysing the number of enrolled students in the Federation of Bosnia and Herzegovina (table 2) for the period from 2009 to 2017, excluding the enrolment in 2015 due to the inaccessibility of adequate data, we can see that the total number of students enrolled has decreased since 2013. In the cumulative comparison of enrolled students in the mentioned period, we notice that among the most popular studies are studies of social and humanistic sciences with a strong increase in the popularity of health studies (figure 1).

Tabela 2. Upisani studenti prema polju obrazovanja u FBiH Table 2. Students enrolled according to the field of education in FB&H

Polje obrazovanja Field of Education

Akademska godina Academic year

2009/10 2010/11 2011/12 2012/13 2013/14 2014/15 2016/17 Obraz. učit.. i nauk. o obr. Teach. educ. and sci. educ. 8474 8880 9094 8576 8132 7328 6321

Umjetnost - Arts 711 888 959 834 920 1394 1114 Humanističke nauke Humanistic sciences 5729 5651 5252 5114 5354 5177 4910

Društvene nauke Social sciences 7501 8477 7969 7964 7989 7331 6037

Novinarstvo i informacije Journalism and information 1852 1825 1832 1745 1240 1160 909

Poslovanje i administr. Business and administration 8024 7530 7464 6483 6229 6310 6499

Pravo - Law 9482 9343 8526 8258 7406 7059 6061 Biološke nauke

Biological sciences 642 765 868 996 1113 1221 1090

Fizikalne nauke Physical sciences 1583 1710 1763 1738 1674 1717 1579

Matematika i statistika Mathematics and statistics 490 527 590 609 706 748 769

Računarstvo- Computing 2111 2517 2484 2243 2415 2787 3654 Inženjerstvo- Engineering 4853 5097 5376 5490 5851 6205 6654 Prerađ. industr. i obrada

Manufactur. and processing 283 357 411 428 406 388 359

Arhitekt. i građevinarstvo Architect. and civil engineer. 2481 2542 2927 3124 3436 3091 3476

Poljopriv., šumar. i ribar. Agric., foresty and fishing 2501 2828 2912 2840 2893 2848 2661

Veterina- Veterinary 512 494 537 493 474 449 449 Zdravstvo- Health 8642 8692 8523 8315 8535 9544 10987

Usluge socijalne zaštite Services of social welfare 2157 2133 2275 2040 2005 1646 1364

Osobne usluge 512 553 525 470 469 379 154


219

Other services Usluge prijevoza

Transport services 995 1184 1440 1698 1739 1555 1712

Zaštita okoline Environmental protection 448 612 752 865 969 867 537

Usluge zaštite Security services 1598 1574 1625 1644 1987 2068 2217

Evropske studija European Studies 59 30 30 29 40 31

Upravljanje državom i nevl. o. Management of the State and

NGOs 17 6 17 15

Rodne studija- Gender studies 18 8 Specijalne namjene- Special

purpose 88 89 88 64

Upravlj. održivim razvoj. Managing Sust. Development 12 22 19

Stručni studij Professional Studies 344 374 369 524 450 342

UKUPNO- TOTAL 71581 74594 74565 72460 72601 71873 69969

Slika 1. Kumulativni prikaz upisanih studenata po poljima obrazovanja u FBiH

0 10000 20000 30000 40000 50000 60000 70000

Obraz. učit.. i nauk. o obr.Umjetnost

Humanističke naukeDruštvene nauke

Novinarstvo i informacijePoslovanje i administr.

PravoBiološke naukeFizikalne nauke

Matematika i statistikaRačunarstvoInženjerstvo

Prerađ. industr. i obradaArhitekt. i građevinarstvoPoljopriv., šumar. i ribar.

VeterinaZdravstvo

Usluge socijalne zaštiteOsobne usluge

Usluge prijevozaZaštita okolineUsluge zaštite

Evropske studijeUpravljanje državom i nevl. o.

Rodne studijeSpecijalne namjene

Upravlj. održivim razvoj.Stručni studij

2009/10 2010/11 2011/12 2012/13 2013/14 2014/15 2016/17


220

Figure 1. Cumulative presentation of enrolled students by fields of education in FB&H

Nažalost studiji prirodnih nauka i tehnologije nisu među najpopularnijim, što nije ni čudno, s obzirom da i literatura naglašava konstantan problem smanjenosti interesovanja za studije iz oblasti prirodnih nauka i tehnologije. Analiza trendova popularnosti upisa po poljima studija pokazuje najveći porast zainteresiranosti za studije iz oblasti zdravstva u zadnje tri godine (slika 2). Ovaj podatak je u skladu sa porastom potražnje kadra iz oblasti zdravstvene njege u zemljama EU. Interesantna i značajna činjenica je da studij inženjerstva je u konstantnom porastu u analiziranom periodu sa stabilnim trendom rasta, dok su studiji iz društvenih i humanističkih nauka u padu u protekle tri godine (slika 3). Nažalost, ostali studiji vezani za prirodne nauke i tehnologiju još nisu stekli željenu popularnost. Studiji iz oblasti informacionih tehnologija je u protekloj godini zabilježio značajniji rast, ali njegov nivo popularnosti nije ni blizu očekivanog s obzirom na značajan porast novonastalih poslova iz oblasti informacionih tehnologija.

Unfortunately, the studies of natural sciences and technology are not among the most popular, which is not surprising, since literature also emphasizes the constant problem of reduced interest in natural science and technology studies. An analysis of trends in enrolment by field of education shows the highest increase in interest in health studies in the last three years (figure 2). This data is in line with the increase in the demand for healthcare personnel in EU countries. An interesting and significant fact is that the study of engineering has been steadily increasing in the analysed period with a stable growth trend, while studies in social and humanistic sciences have been declining over the past three years (figure 3). Unfortunately, other studies related to natural science and technology have not yet gained the desired popularity. Information technology studies have recorded significant growth in the past year, but its level of popularity is not nearly as expected, given the significant increase in newly emerging IT jobs and positions.

0 10000 20000 30000 40000 50000 60000 70000

Teach. educ. and sci. educ.Arts

Humanistic sciencesSocial sciences

Journalism and informationBusiness and administration

LawBiological sciences

Physical sciencesMathematics and statistics

ComputingEngineering

Manufactur. and processingArchitect. and civil engineer.

Agric., foresty and fishingVeterinary

HealthServices of social welfare

Other servicesTransport services

Environmental protectionSecurity services

European StudiesManagement of the State and NGOs

Gender studiesSpecial purpose

Managing Sust. DevelopmentProfessional Studies

2009/10 2010/11 2011/12 2012/13 2013/14 2014/15 2016/17


221

Slika 2. Prikaz trenda upisa studenata po poljima obrazovanja u FBiH

0

2000

4000

6000

8000

10000

12000

2009/10 2010/11 2011/12 2012/13 2013/14 2014/15 2016/17

Obraz. učit.. i nauk. o obr. Umjetnost Humanističke nauke

Društvene nauke Novinarstvo i informacije Poslovanje i administr.

Pravo Biološke nauke Fizikalne nauke

Matematika i statistika Računarstvo Inženjerstvo

Prerađ. industr. i obrada Arhitekt. i građevinarstvo Poljopriv., šumar. i ribar.

Veterina Zdravstvo Usluge socijalne zaštite

Osobne usluge Usluge prijevoza Zaštita okoline

Usluge zaštite Evropske studije Upravljanje državom i nevl. o.

Rodne studije Specijalne namjene Upravlj. održivim razvoj.

Stručni studij


222

Figure 2. Presentation of students’ enrolment trends by fields of education in FB&H

0

2000

4000

6000

8000

10000

12000

2009/10 2010/11 2011/12 2012/13 2013/14 2014/15 2016/17

Teach. educ. and sci. educ. Arts

Humanistic sciences Social sciences

Journalism and information Business and administration

Law Biological sciences

Physical sciences Mathematics and statistics

Computing Engineering

Manufactur. and processing Architect. and civil engineer.

Agric., foresty and fishing Veterinary

Health Services of social welfare

Other services Transport services

Environmental protection Security services

European Studies Management of the State and NGOs

Gender studies Special purpose

Managing Sust. Development Professional Studies


223

Slika 3. Poređenje trenda upisa studenata po analiziranim poljima obrazovanja u FBiH

Obraz. učit.. i nauk. o obr.

Humanističke nauke

Društvene nauke

Poslovanje i administr.

Pravo

Biološke nauke

Matematika i statistika

Računarstvo

Inženjerstvo

Zdravstvo

0

2000

4000

6000

8000

10000

12000

2009/10 2010/11 2011/12 2012/13 2013/14 2014/15 2016/17

Axis

Title


224

Figure 3. Comparison of student enrolment trends in analysed fields of education in FB&H 3. ZAKLJUČNA RAZMATRANJA Pored investiranja u atraktivnost studija nauke i tehnologije, obrazovne institucije mogu odlučiti da angažuju predmetne specijaliste za predavanje predmete vezanih za nauku i tehnologiju s obzirom da entuzijazam nastavnika i profesora igra važnu ulogu u formiranju pozitivnih stavova studenata. Na taj način učenici i studenti mogu imati koristi od predavača ispunjenog entuzijazmom i koji se osjeća samouvjereno i kompetentno u predmetima koje predaje. U ovom radu pokušali smo da analiziramo problematiku koja se tiče opadanja interesa za nauku i tehnologiju u obrazovnim institucijama.

3. CONCLUDING REMARKS In addition to investing in the attractiveness of science and technology studies, educational institutions can decide to hire subject specialists to teach science and technology subjects as the enthusiasm of teachers and professors plays an important role in shaping students' positive attitudes. In this way, students can benefit from an enthusiastic lecturer who feels confident and competent in the subjects he teaches. In this paper, we have tried to analyse the problem of declining interest in science and technology in educational institutions.

Teach. educ. and sci. educ.

Humanistic sciences

Social sciences

Business and administration

Law

Biological sciences

Mathematics and statistics

Computing

Engineering

Health

0

2000

4000

6000

8000

10000

12000

2009/10 2010/11 2011/12 2012/13 2013/14 2014/15 2016/17

Axis

Title


225

Ustanovili smo da je navedeni pad interesovanja rasprostranjen čak i u Bosni i Hercegovini. To nije ni čudno, s obzirom da u poređenju sa drugim akademskim predmetima, predmeti nauke i tehnologije se smatraju sve težim i važnijim. Interesantno je i saznanje da je studij inženjerstva u konstantnom porastu sa stabilnim trendom rasta u Federaciji Bosne i Hercegovine, dok su studiji iz društvenih i humanističkih nauka u padu u proteklim godinama. Poražavajuća je činjenica da ostali studiji vezani za prirodne nauke i tehnologiju još uvijek nisu stekli željeni nivo popularnosti, te je stoga i nivo interesovanja za iste nedovoljno stimuliran. Najveći porast zainteresiranosti nalazimo u studijima vezanim za oblast za zdravstva. Ovaj porast nije iznenađujući, nego je u čak i logičan, s obzirom na veliki porast potražnje kadra iz oblasti zdravstvene njege u zemljama EU. Studiji iz oblasti informacionih tehnologija je u protekloj godini zabilježio značajniji rast, ali njegov nivo popularnosti nije ni blizu očekivanog s obzirom na značajan porast novonastalih poslova iz oblasti informacionih tehnologija. Navedena saznanja daju nam uvid u popularnost različitih studija u FBiH. Vlada zajedno sa akademskom zajednicom bi trebala da se ozbiljnije pozabavi navedenim problemom i da uđe u savremene trendove i tokove kroz stimulaciju studija sa većim prosperitetom zapošljavanja te da na taj način reducira stepen nezaposlenosti kao i stepen hiperprodukcije kadrova. Cilj ovog istraživanja je podizanje svijesti o zanemarivanju podsticanja studija iz oblasti tehničkih nauka kao i stimulaciji mladih da upišu studije tehničke struke. Stoga, ovo istraživanje predstavlja uvod za buduća istraživanja o atraktivnosti studija tehničkih nauka, kao i osnov za rješavanje problema nedovoljnog interesovanja za tehničke predmete i oblasti.

We found that this decline in interest is widespread even in Bosnia and Herzegovina. This not even strange considering that, compared to other academic subjects, subjects of science and technology are considered increasingly difficult and more important. It is also interesting that the study of engineering is constantly increasing with a stable growth trend in the Federation of Bosnia and Herzegovina, while studies in social and humanistic sciences have been declining in recent years. It is a devastating fact that other natural science and technology studies have not yet reached the desired level of popularity, and therefore the level of interest in them is not sufficiently stimulated. The greatest increase in interest is found in health-related studies. This increase is not surprising, but it is even logical, given the high demand for health care personnel in EU countries. Information technology studies have recorded significant growth in the past year, but its level of popularity is not nearly as expected, given the significant increase in newly emerging IT positions and jobs. These findings give us an insight into the popularity of various studies in the FB&H. The government together with the academic community should seriously address this problem and enter contemporary trends through the stimulation of studies with greater prosperity of employment, thus reducing the level of unemployment as well as the level of personnel hyperproduction. The aim of this research is to raise awareness of the neglect of encouraging studies in the field of technical sciences as well as stimulating young people to enrol in technical studies. Therefore, this research represents an introduction for future research on the attractiveness of technical science studies, as well as the basis for solving the problem of insufficient interest in technical subjects and areas.

4. LITERATURA-REFERENCES [1] Barmby P, Kind PM, Jones K (2008):

Examining changing Attitudes in secondary school science, International Journal of Science Education. 30(8) pp. 1075–1093.

[2] Beilock SL, Gunderson EA, Ramirez G, Levine SC (2010): Female teachers’ math anxiety affects girls’ math achievement, Proceedings of the National Academy of

Sciences of the United States of America, vol. 107, no. 5, pp. 1860–1863.

[3] Cavas P (2011): Factors affecting the motivation of Turkish primary students for science learning, Science Education International 22(1), pp. 31–42.

[4] Davis HA (2003): Conceptualizing the role and influence of student-teacher relationships on children’s social and


226

cognitive development, Educational Psychologist, vol. 38, no. 4, pp. 207–234.

[5] Elwood J, Comber C (1996): Gender differences in A level examinations: new complexities or old stereotypes? The British Journal of Curriculum and Assessment, vol. 6, no. 2, pp. 24–29.

[6] Frenzel AC, Goetz T, Ludtke O, Pekrun R, Sutton RE (2009): Emotional transmission in the classroom: exploring the relationship between teacher and student enjoyment, Journal of Educational Psychology, vol. 101, no. 3, pp. 705–716.

[7] Gottfried AE, Marcoulides GA, Gottfried AW, Oliver PH (2009): A latent curve model of parental motivational practices and developmental decline in math and science academic intrinsic motivation, Journal of Education Psychology 101(3):729–739.

[8] Hill C, Corbett C, St. Rose A (2010): Why So Few? Women in Science, Technology, Engineering and Mathematics, AAUW, Washington, DC, USA.

[9] Kind P, Jones K, Barmby P (2007): Developing attitudes towards science measures, International Journal of Science Education, vol. 29, no. 7, pp. 871–893.

[10] Krapp A, Prenzel M (2011): Research on interest in science: theories, methods, and findings. International Journal of Science Education 33(1):27–50.

[11] OECD, PISA (2006): Science Competencies for Tomorrows World, OECD Programme for International Student Assessment.

[12] Osborne J, Simon S (1996): Primary science: past and future directions, Studies in Science Education, vol. 27, pp. 99–147.

[13] Osborne J, Simon S, Collins S (2003): Attitudes towards science: a review of the literature and its implications, International Journal of Science Education, vol. 25, no. 9, pp. 1049–1079.

[14] Osborne J, Simon S, Tytler R (2009): Attitudes towards science: an update, Proceedings of the Annual Meeting of the American Educational Research Association, San Diego, Calif, USA, April.

[15] Palmer D (2004): Situational interest and the attitudes towards science of primary teacher education students, International Journal of Science Education, vol. 26, no. 7, pp. 895–908.

[16] Pan Y, Gauvain M (2012): The continuity of college students’ autonomous learning motivation and its predictors: a three-year longitudinal study. Learning and Individual Differences 22(1):92–99.

[17] Potvin, P., Hasni, A. (2014): Analysis of the decline in interest towards school science and technology from grades 5 through 11, Journal of Science Education and Technology, 23(6), 784-802.

[18] Reid N, Skryabina EA (2002): Attitudes towards physics. Research in Science and Technology Education 20(1), pp. 67–81.

[19] Singh K, Granville M, Dika S (2002): Mathematics and science achievement: effects of motivation, interest, and academic engagement, The Journal of Educational Research 95(6):323–332.

[20] Statistički bilteni, Federalni zavod za statistiku Bosne i Hercegovine, 2009-2017. godina, http://fzs.ba/

[21] Trumper R (1998): The need for change in elementary-school teacher training: the force concept as an example, Asia-Pacific Journal of Teacher Education, vol. 26, no. 1, pp. 7–25.

[22] Venturini P (2004): Note de synthèse - Attitudes des élèves envers les sciences: le point des recherches. Revue francaise de pe´dagogie 149, pp. 97–121.

[23] Wilkins JLM (2010): Elementary school teachers’ attitudes toward different subjects, The Teacher Educator, vol. 45, no. 1, pp. 23– 36.

Coresponding author: Arnaut Dino University of Zenica, Faculty of Economics Fakultetska 3 72000 Zenica e-mail: [email protected] tel.: +387 61 422246

MAIN TOPICS 1. MANUFACTURING TECHNOLO-

GIES AND MATERIALS Assembly and Disassembly; Machining, Nonconventional Machining, Tools, High Speed Machining; Dry Cutting, MQL Ma-chining, High Performance Machining, Rapid Prototyping, Micromachining, Manu-facturing Processes, Welding Processes; Plastic Forming Processes; Materials; Engineering of Polymers; Powder Metallur-gy; Measuring; Thin & Thick Coatings; Surface Engineering; Molding Processes; CAM technologies; ...other subtopics 2. INDUSTRIAL ENGINEERING Diagnostic; Expert Systems; Autonomous Systems; Environmental Design; Reengi-neering; Knowledge Based Systems; Robot Applications; Mobile Robots; Optimi-zations, Reliability, Safety, Production Systems, Agile Manufacturing, Concurrent Manufacturing; Control, Flexible Manufac-turing Systems; Hybrid Manufacturing Systems; CAP technologies; CIM technol-ogies; Knowledge Management, Project Management, Production Management Systems, Quality Management, TQM, Maintenance, Nondestructive Testing, Operational Research Applications in Production, Scheduling, Supply Chain Management, Logistics, Electrical Engi-neering, Power Systems, Energetic; Ecolo-gy, Environmental Engineering ...other subtopics 3. APPLIED TECHNOLOGIES AND SOFTWARE ENGINEERING Software Engineering Applications, Sen-sors; Industrial Robots; Microrobotics; Programming; Simulations, Virtual Manu-facturing; Industrial Automation; Hardware & Software; Signal Processing, Network-ing; Neural Network; Artificial Intelligence, Engineering Education Systems ...other subtopics 4. MECHANICAL CONSTRUCTIONS & DESIGN Design and Construction; Design Automa-tion; Robots- Kinematics, Dynamics; Mechanism; Numerical Methods; Optimal Design, Tolerance Analysis; CAD technol-ogies; Environmental Design, Fluid Me-chanics, Mechatronics ...other subtopics

The Organizing Committee invites authors and participants to submit paper title and abstract (max. 20 typewritten lines, in English language), not later than March 15th 2018, addressed to the organizer. Please, identify the topic area in which your article should be included. The official language of the Conference is English. The papers accepted by reviewers will be printed in the Conference Proceed-ings only if registration fee is paid before June 15th 2018. Presentation of the paper can be either on poster or orally. All papers, including posters, will be includ-ed in Proceedings of the Conference. ONLY ORALLY PRESENTED PAPERS will be included in Journal of Trends in the Development of Machinery and Associated Technology. The Journal is availa-ble online - ISSN 2303-4009 (online). Each author can have maximally 3 papers published in the pro-ceedings.

21th International Research/Expert Conference ”Trends in the Development of Machinery and Associated Technology”

TMT 2018, Karlovy Vary, Czech Republic 17th - 23th September, 2018

CONFERENCE FEE:

250,00 EUR + 25,00 EUR (for poster presentation)

THE POSTERS WILL BE PREPARED BY ORGANIZER! The conference fee includes a copy of Conference Proceedings and accompanying materials, admis-sion to all sessions and presentations.

University of Zenica Faculty of Mechanical Engineering Bosnia and Herzegovina

Universitat Politècnica de Catalunya ETSEIB-DEM Barcelona, Spain

Bahçeşehir Üniversitesi Istanbul, Turkey

PLACE of EVENTS - KARLOVY VARY, CZECH REPUBLIC

SEND YOUR ABSTRACTS TO:

E-mail: [email protected] [email protected]

MORE INFORMATION AVAILABLE ON: Web: http://www.tmt.unze.ba

IMPORTANT DATES

Submission of abstracts...................... March 15th 2018 Submission of the full paper ................. May 15th 2018 Registration fee payment ...................... June 15th 2018 Final Programme ................................... July 15th 2018 TMT 2018 ....................... September 17th to 23th 2018

For additional information on booking please, contact Travel agency:

http://www.centrotours.ba

Assoc. Prof. Dr. Jesus-Andres Alvarez (Spain) Prof.Dr. Radovan Antonic (Croatia)

Prof.Dr. Ivan Anzel (Slovenia) Prof.Dr. Lutfi Arda (Turkey)

Prof.Dr. Drazen Bajic (Croatia) Prof.Dr. Senad Balic (B&H) Prof.Dr. Hazim Basic (B&H)

Assoc.Prof.Dr. Ahmet Beskese (Turkey) Prof.Dr. Izet Bijelonja (B&H)

Assoc.Prof.Dr. Farzet Bikic (B&H) Prof.Dr. Safet Brdarevic (B&H)

Assoc.Prof.Dr. Irene Buj (Spain) Assoc.Prof.Dr. Dzevad Burgic (B&H)

Prof.Dr. Ilhan Busatlic (B&H) Assoc.Prof.Dr. F. Tunc Bozbura (Turkey)

Prof.Dr. Gabriel Bugeda (Spain) Prof.Dr. Shaban Buza (Kosovo)

Prof.Dr. Miodrag Bulatovic (Montenegro) Assoc.Prof.Dr. Malik Cabaravdic (B&H)

Prof.Dr. Salvador Cardona (Spain) Prof.Dr. Alicia Casals (Spain)

Asst.Prof.Dr. Yalcin Cekic (Turkey) Assoc. Prof. Dr. Lluis Solano (Spain)

Prof.Dr. Ilija Cosic (Serbia) Prof.Dr. Dragan Cvetkovic (Serbia)

Prof.Dr. Laszek A. Dobrzanski (Poland) Prof.Dr. Vlatko Dolecek (B&H)

Prof.Dr. Slavko Dolinsek (Slovenia) Prof.Dr. Joze Duhovnik (Slovenia)

Prof.Dr. Himzo Dukic (B&H) Prof.Dr. Ejub Dzaferovic (B&H)

Prof.Dr. Sabahudin Ekinovic (B&H) Prof.Dr. Elma Ekinovic (B&H)

Assoc.Prof.Dr. Levent Eren (Turkey) Prof.Dr. David de la Fuente (Spain)

Assoc. Prof. Dr. Manel Mateo (Spain) Prof.Dr. Hirpa L. Gelgele (Norway)

Prof.Dr. Zvonimir Guzovic (Croatia) Asst.Prof.Dr. Orhan Gokcol (Turkey)

Prof.Dr. Sefket Goletic (B&H) Assoc.Prof.Dr. Hernan A. Gonzalez (Spain)

Prof.Dr. Roberto Grino (Spain) Asst.Prof.Dr. Berke Gur (Turkey)

Prof.Dr. Csaba Gyenge (Romania) Asst.Prof.Dr. Fuad Hadzikadunic (B&H)

Prof.Dr. Nađija Haracic (B&H) Prof.Dr. Nedim Hodzic (B&H)

Prof.Dr. Safet Isic (B&H) Assoc.Prof.Dr. Sabahudin Jasarevic (B&H)

Prof.Dr. Milan Jurkovic (Croatia) Prof.Dr. Bilgin Kaftanoglu (Turkey)

Prof.Dr. Isak Karabegovic (B&H)

ORGANIZING COMMITTEE Prof.Dr. Sabahudin Ekinovic, President Prof.Dr. Senay Yalcin, Co-president Assoc.Prof.Dr. Irene Buj Corral, Co-President Asst.Prof.Dr. Edin Begovic, Secretary Prof.Dr. Francesc Roure Fernandez Prof.Dr. Joan Vivancos-Calvet Prof.Dr. Darko Petkovic Assoc.Prof.Dr. Elma Ekinovic Asst.Prof.Dr. Sabahudin Jasarevic Asst.Prof.Dr. Ibrahim Plancic Prof.Dr. Lutfi Arda Assoc.Prof.Dr. Hernan A. Gonzalez Rojas Assoc.Prof.Dr. Carles Riba Romeva Assoc.Prof.Dr. F. Tunc Bozbura Assoc.Prof.Dr. Ahmet Beskese Assoc.Prof.Dr. Jose A.T. Rodriguez Kemal Arifovic, IT support

Prof.Dr. Sabahudin Ekinovic, President (B&H) Prof.Dr. Ali Gungor, Co-President (Turkey)

Assoc.Prof.Dr. Neus Consul-Porras , Co-President (Spain)

21th International Research/Expert Conference ”Trends in the Development of Machinery and Associated Technology”

TMT 2018, Karlovy Vary, Czech Republic 17th - 23th September, 2018

Prof.Dr. Darko Knezevic (B&H) Prof.Dr. Adem Karahoca (Turkey) Prof.Dr. Munir Khamashta (Spain) Prof.Dr. Janez Kopac (Slovenia) Prof.Dr. Ramon Lopez (Spain) Prof.Dr. Carmelo J. Luis (Spain) Prof.Dr. Antoni Martinez (Spain) Assoc.Prof.Dr. Jordi Martinez (Spain) Prof.Dr. Muhamed Mehmedovic (B&H) Prof.Dr. Sulejman Muhamedagic (B&H) Prof.Dr. Rajfa Musemic (B&H) Prof.Dr. Nagib Neimarlija (B&H) Prof.Dr. Branko Novakovic (Croatia) Prof.Dr. Eugenio Onate (Spain) Prof.Dr. Mirsada Oruc (B&H) Prof.Dr. Baris Ozerdem (Turkey) Prof.Dr. Mugdim Pasic (B&H) Prof.Dr. Sead Pasic (B&H) Prof.Dr. Darko Petkovic (B&H) Asst.Prof.Dr. Ibrahim Plancic (B&H) Prof.Dr. Viera Poppeova (Slovakia) Prof.Dr. J. Manuel Prado (Spain) Assoc.Prof.Dr. Carles Riba (Spain) Dr. Milenko Rimac (B&H) Assoc.Prof.Dr. Jose A. T. Rodriguez (Spain) Assoc. Prof. Dr. Jordi Romeu (Spain) Prof.Dr. Francesc Roure (Spain) Assoc.Prof.Dr. Maria-Antonia de los Santos (Spain) Prof.Dr. Mirko Sokovic (Slovenia) Assoc.Prof.Dr. Alkan Soysal (Turkey) Prof.Dr. Jovan Sredojevic (B&H) Prof.Dr. Antun Stoic (Croatia) Prof.Dr. Zeljko Stojkic (B&H) Prof.Dr. Suada Sulejmanovic (B&H) Assoc.Prof.Dr. Amra Talic-Cikmis (B&H) Prof.Dr. Nadezda Talijan (Serbia) Prof.Dr. Stefano Tornincasa (Italy) Prof.Dr. Xavier Tort-Martorell (Spain) Prof.Dr. Dzemo Tufekcic (B&H) Assoc.Prof.Dr. Alper Tunga (Turkey) Asst. Prof. Dr. Gorkem Uctug (Turkey) Prof.Dr. Kanji Ueda (Japan) Asst.Prof.Dr. Demet Ozgur Unluakin (Turkey) Prof.Dr. Gyula Varga (Hungary) Prof.Dr. Joan Vivancos (Spain) Assoc.Prof.Dr. Nedeljko Vukojevic (B&H) Prof.Dr. W. Wisutmethangoon (Thailand) Prof.Dr. Senay Yalcin (Turkey) Prof.Dr. Dzevad Zecic (B&H) Prof.Dr. Dragana Zivkovic (Serbia) Prof.Dr. Miodrag Zlokolica (Serbia)

CORRESPONDENCE Prof.Dr. Sabahudin Ekinovic Asst.Prof.Dr. Edin Begovic University of Zenica Faculty of Mechanical Engineering Fakultetska 1, 72000 Zenica Bosnia and Herzegovina Phone: + 387 32 449 135 Fax: + 387 32 246 612 E-mail: [email protected] [email protected] Web: http://www.tmt.unze.ba

POZIV AUTORIMA I UČESNICIMA

Organizacioni odbor poziva sve zainteresovane autore i učesnike da naslov rada i abstrakt

(do 100 kucanih riječi) pošalju na adresu organizatora [[email protected]] ili

[[email protected]] (sa naznakom oblasti na koju se rad odnosi).

Službeni jezici Simpozija su: engleski i BHS jezici. Abstrakti i kompletni radovi se

dostavljaju prema uputstvu na engleskom jeziku.

TEMATIKA SIMPOZIJA

Naučno/stručni simpozij će raditi na slijedeći način: plenarna sjednica (uvodni i pozivni

radovi za globalne teme), simpozij (usmena i poster prezentacija radova po temama skupa), i

po potrebi radni sastanci. Obavještavaju se svi potencijalni autori da mogu pripremiti radove

iz slijedećih oblasti:

Metalni materijali Nemetalni materijali (anorganski, organski i građevinski materijali)

Zaštita radne i životne sredine i održivi razvoj

ZNAČAJNI DATUMI

Prijava abstrakta radova U toku Obavijest o prihvatanju abstrakta i dostava uputstava za pisanje radova U toku Prijava kompletnih radova 01.03.2018 Obavijest o prihvatanju radova 31.03.2018 Plaćanje kotizacije 10.04.2018 Finalni program 15.04.2018

Održavanje Simpozija MNM2018 19.-20.04.2018

Mjesto održavanja VLAŠIĆ

KOTIZACIJA

Kotizacija za autore i učesnike Simpozija je 100,00 € neto (~ 200,00 KM), uključujući i članove Naučnog odbora i predsjedavajuće Sekcija. Kotizacija obuhvata Zbornik radova sa Simpozija sapratećim materijalima, piće dobrodošlice i svečanu večeru prvog dana održavanja

CONFERENCE DATE AND VENUEThe conference will be held from to 20 in10 12 May 8 Hotelth th 1Zenica, osnia and erzegovina.Zenica, B HZenica is a town in the Zenica-Doboj Canton, in the central part ofBosnia and Herzegovina. Area of the city is 500 km ², population isabout 130 thousand. Economic center of the geographic region ofcentral Bosnia and near Travnik and Jajce, the most important cityin that part of the state.

INVITATION TO THE AUTHORS ANDPARTICIPANTS

Organizing Committee would like to invite all potential authorsand participants to submmit abstracts (up to 100 words), not laterthan 20 The official Conference languages areFebruary 15 18st

English, Bosnian, Serbian and Croatian.On line registration on www. .unze.baodrzavanje

CONFERENCE OBJECTIVES

Conference objectives are:- Gathering of people engaged in maintenance funds for theoperation of various aspects and their structural organization,- Communication of the results of research in the field ofmaintenance, as theoretical and practical,- Exchange of experiences from practical maintenanceactivities,- Transfer of knowledge in the field of maintenance.

CONFERENCE TOPICSThe will be performed as follows: plenary sessionConference(Ke papers concerned global topics), symposium (papersyaccording to the conference topics) and workshops, whenneeded. We would like to inform all the potential authors toprepare papers in the following topics:1. Technology maintenance2 Reliability and maintenance.3 Logistics in the maintenance.4 Quality and maintenance.5 Monitoring and Diagnostics.6 M and maintenance. anagement7 Information systems maintenance.8 New technologies in the maintenance.9 Education Maintenance.10. Human resources in maintaining1 Asset management1.1 acility Management2. F1 utsourcing3. O1 isk Management4. R1 Ecology and aintenance5. M1 nventory Management6. I1 Cost of maintenance7.18. Safety at work19. Performance indicators of maintenance20. Trends in Maintenance

CONFERENCE FEEThe conference fee for authors and participants is 1 0,00 EUR5(including members of the Scientific Committee, and sessionchairmen). The conference fee include: conference proceedings andaccompanying materials, admission to all sessions and presentations,refreshments, and welcome drink.

ACCOMPANYING EVENTSWe hereby inform interested companies and manufacturers ofequipment and devices for maintenance to be able to rent exhibitspace or to make a presentation of the company or equipment withinthe planned sessions.

IMPORTANT DATES

� Submission of abstracts . ............... .. .... 20 .. ...... .. .... . February 15 18th

· Notification of acceptance of theabstracts and instructions forpreparing the papers . ...................... . .. ... 20 ... . . .. February 20 18...... .. th

� Submission of the full paper ............... ... .......... 20 .......... . April 01 18st

� Registration fee payment........... .... ... .. ..... 20 ....... . . ...... .... May. 01 18st

� Final Programme ............................. .......... .. 20 .... ... . 01 18. . .. .... May st

� ........ ........ .... to 20 .MAINTENANCE 2018 .. May 10 12 18..... ... ..... ... th th

WELCOME

TO

ZENICA

Sve informacije u vezi Skupa možete dobiti na:You can get all the information regarding the Conference at:

telefone : +387 32 449-143, 449-145,/phonefax:+387 32 246-612

E-mail: [email protected];s jasar @abahudin evic yahoo.com

[email protected]

Osobe za kontakt :- You can also contact:- Sabahudin Jašarević -presidentDr.

Dr. Safet Brdarević,- - secretarEmir Đulić y

- 201 , Zenica,10 12 May 8Bosnia and Herzegovina

ODR 2ŽAVANJE 018MAINTENANCE 2018

CONFERENCE5th

UN

I

VE

RS I T Y O F

ZE

N

IC

A

UN

IV

ER

SIT

AS

STUDIO RUMZ

E

NIC

AE

NS

IS

UN

IV

ER

SIT

AS

S T U D I O R U MZ

E

NIC

AE

NS

IS

UN

I

VE

R Z I T E T UZ

EN

IC

I

UDRUŽENJEDRUŠTVO ODRŽAVALACAU BOSNI I HERCEGOVINI

UNIVERSITY OF ZENICA(Bosnia and Herzegovina)

FACULTY OF MECHANICALENGINEERING

DRUŠTVO ODRŽAVALACAU BOSNI I HERCEGOVINIA „SSSOCIATION OCIETYOF AINTAINERS INMB H “OSNIA AND ERZEGOVINA

CALL FOR PARTICIPATION AND FIRST ANNOUNCEMENT:

4thInternational"New Technologies NT

4thInternational Conference"New Technologies NT

Dear Colleagues, It is my pleasure to invite you to attend Technologies NT-2018".The Conference hosts areBosnia and Herzegovina, Society for RobotiMostar, University of Tuzla, University of Zenica, University of Sarajevoof Science and Technology, International University of Sarajevo, Society for Advanced Technology and Technology park INTERA. from 14th to 16th June 2018. The cexchange knowledge and to implement new technologies in practice. All information about the conference, including topics, deadconference webpage: www.icnt.robotika.baSubmitted paper should be written in four to eight (4 For further questions you may contact us by [email protected]. Sincerely ! Contact person:Isak Karabegović[email protected] We kindly request that you forward this announcement to other colleagues who might be interested.

www.icnt.robotika.ba

Sarajevo, 14ACADEMY OF SCIENCES AND ARTS

OF BOSNIA AND HERZEGOVINA

PUBLISHER

http://www.springer.com/series/15


International Conference "New Technologies NT-2018"

SPONSOR

International Conference "New Technologies NT-2018"

It is my pleasure to invite you to attend the 4th International Conference "New Conference hosts are: Academy of Sciences and Arts of

Herzegovina, Society for Robotics of Bosnia and Herzegovina, University of ty of Tuzla, University of Zenica, University of Sarajevo, Sarajevo School

, International University of Sarajevo, Society for Advanced Technology park INTERA. The conference will be held in Sarajevo

conference will gather scientists and entrepreneurs to exchange knowledge and to implement new technologies in practice. All information about

including topics, deadlines, manuscript templates, etc.are available at the www.icnt.robotika.ba

Submitted paper should be written in four to eight (4 - 8) pages. contact us by e-mail:

Isak Karabegović, University of Bihać, BA

you forward this announcement to other colleagues who

www.icnt.robotika.ba

Sarajevo, 14th-16th, June 2018 EMY OF SCIENCES AND ARTS

OF BOSNIA AND HERZEGOVINA

SOCIETY FOR ROBOTICS

ORGANIZER

●

CO

●SARAJEVO SCHOOLOF SCIENCE AND

●

●

BURCH UNIVERSITY

/15179


2018"

SOCIETY FOR ROBOTICS OF BOSNIA

AND HERZEGOVINA

ORGANIZER

●TECHNOLOGY PARK INTERA OF MOSTAR

CO-ORGANIZERS

●UNIVERSITY “DŽEMAL BIJEDIĆ”

OF MOSTAR

●UNIVERSITY OF

TUZLA

●UNIVERSITY OF ZENICA

●UNIVERSITY OF SARAJEVO

●SARAJEVO SCHOOL OF SCIENCE AND

TECHNOLOGY

●INTERNATIONAL UNIVERSITY OF

SARAJEVO

●SOCIETY FOR ADVANCED

TECHNOLOGY

●FOREIGN TRADE CHAMBER OF BOSNIA AND

HERZEGOVINA

●INTERNATIONAL BURCH UNIVERSITY

OF SARAJEVO

Mašinstvo 4(14), 232 – 236 (2017) N. Surname 1 et al.: TITLE OF PAPER….

232

INSTRUKCIJE ZA AUTORE (Style: Times New Roman, 14pt, Bold)

INSTRUCTIONS FOR AUTHORS (Style: Times New Roman, 14pt, Bold)

Name Surname 1, Name Surname 2, Name Surname X (Author's name, Co-author's name - Style: Times New Roman, 11pt, Bold) Authors’Institution (Style: Times New Roman, 11pt) Ključne riječi: abecedni popis ključnih riječi na bosanskom, hrvatskom ili srpskom jeziku (Style: Times New Roman, 10pt) Keywords: Alphabetic list of keywords in English (Style: Times New Roman, 10pt) Paper received: xx.xx.xxxx. Paper accepted: xx.xx.xxxx.

Kategorizacija članka (Style: Times New Roman, 10pt, Bold, Italic) REZIME (Style: Times New Roman, 10pt, Bold) Naslov rada (do 15 riječi). Puna imena i prezimena autora (bez navođenja zvanja i akademskih titula). Rezime rada (do 150 riječi). Rezime treba što vjernije odražavati sadržaj rada. U njemu se navode upotrebljene metode i ističu ostvareni rezultati kao i doprinos rada. Naslov, rezime rada i ključne riječi autori sa ex-YU prostora pišu i na bosanskom, hrvatskom ili sprskom jeziku. Ključne riječi u pravilu su iz naslova rada, a samo eventualno iz sažetka rada. Ovaj dio rada se ne lektoriše i autori su odgovorni za njegovu jezičnu i gramatičku ispravnost. Nakon završetka recenzentskog postupka autori mogu biti zamoljeni da naprave određene popravke ili dopune svoj rad. (Style: Times New Roman, 10pt, Italic)

Categorization of paper (Style: Times New Roman, 10pt, Bold, Italic)

SUMMARY (Style: Times New Roman, 10pt, Bold) Title of the paper (up to 15 words). The full list of authors (without specifying grades and ranks). Summary (up to 150 words). Summary should be as faithfully reflect the content of the paper. It outlines the methods used and highlight the results achieved as well as the contribution of the paper. Title, summary of paper and keywords, authors from ex-Yugoslavia area, write to the Bosnian, Croatian or Serbian languages. Keywords are generally from the title of paper, and just possibly from the summary. This part of the paper is not proofread and authors are responsible for the linguistic and grammatical correctness. After completion of the review process, authors may be asked to make certain repairs or additions to their paper. (Style: Times New Roman, 10pt, Italic)

1. INTRODUCTION (Style: Times New Roman, 11pt, Bold)

Upon its acceptance the article is categorized as follows: original scientific paper, preliminary notes, subject review, professional paper and conference paper. Original scientific papers should report original theoretical or practical research results. The given data must be sufficient in order to enable the experiment to be repeated with all effects described by the author, measurement results or theoretical calculations. Preliminary notes present one or more new scientific results but without details that allow the reported data to be checked. The papers of this category inform about experimental research, small research projects or progress reports that are of interest.

Subject reviews cover the state of art and tendencies in the development of the specific theory, technology and application with given remarks by the author. Such a paper ends with a list of reference literature with all the necessary items in the related field. Professional papers report on the original design of an instrument, device or equipment not necessarily resulting from the original research. The paper contributes to the application of well-known scientific results and to their adaptation for practical use. Papers presented at scientific conferences can also be published in the journal upon the agreement of the conference organizer and the author. (Style: Times New Roman, 11pt, Normal) Papers to be published in the journal Tehnički vjesnik/Technical Gazette, should be written in


233

English. The metrology and terminology used in the paper have to meet legal regulations, standards and International System of Units (SI) 1.1. Subtitle 1 (Writing Instructions)

(Style: Times New Roman, 11pt, Bold) The text of the paper is arranged in sections and when necessary into subsections. Sections are marked with one Arabic numeral and subsections with two Arabic numerals, e.g. 1.1., 1.2., 1.3., ... When a subsection is arranged in smaller parts, each of them is marked with three Arabic numerals, e.g. 1.1.1., 1.1.2., ... Further divisions are not allowed. The text has to be organized in the following order: Title of the paper (up to 15 words). Papers should be headed by a concise but informative title that clearly reflects the subject of the paper. Authors' full names (without grades and ranks). Summary-Abstract (up to 150 words) should present a brief and factual account of content and conclusions of the paper, and an indication of the relevance of the new material presented. Title and abstract in Bosnian/Croatian/Serbian (BCS). Only for authors from ex-Yugoslavian area. Alphabetic list of keywords in English and in (BCS). Keywords normally originate from the title and from the abstract. Introduction should state the reason for the work, with brief reference to previous work on the subject. It informs about the applied method and its advantages. Central part of the paper may be arranged in sections. Complete mathematical procedures for formula derivations should be avoided. The necessary mathematical descriptions may be given in an appendix. Authors are advised to use examples to illustrate the experimental procedure, applications or algorithms. In general all the theoretical statements have to be experimentally verified. In Conclusions all the results are stated, and all the advantages of the used method are pointed out. The limitations of the method should be clearly described as well as the application areas. List of references should be brought together at the end of the article and numbered in square brackets in order of their appearance in the text followed by other literature. Coressponding authors' full names followed by the name and address of the institution in which the work was carried on. A List of used symbols and theirs SI units is optional after list of references.

1.1.1. Subtitle 2 (Preparation of Manuscript) (Style: Times New Roman, 11pt, Bold)

The paper should be written using Latin characters. Greek letters may be used for symbols. The volume of the article is limited to 10 pages (A4 format). That includes blanks and equivalent number of characters covered by figures and tables. Number of pages must be even. The text should be sent to the Editorial Board using e-mail. For the text preparing may be used only MS Word for Windows respectively *.doc, *.docx (Word Document) or *.rtf (Rich Text Format) format of records. The text has to be prepared in accordance with this template. The Editorial Board may exceptionally request the CD-ROM with recorded articles and figures and tables. In that case the figures (drawings, diagrams and photographs) should be submitted stored on the CD-ROM in JPG/JPEG, PNG, TIF (TIFF Bitmap) or BMP (Windows Bitmap) format, min. resolution of 300 dpi. Each figure is labelled the same as it is in the paper and recorded format (e.g. fig-1.JPG). If figures inserted into text they must be also with min. resolution of 300 dpi. Latin or Greek characters in italics are used for physical symbols and normal characters for measuring units and numerical values. Text in figures is also written with normal letters. Character size is to be chosen on the basis of the following criteria: after expected figure size reduction a capital Latin character should be about 2 mm high (no less than 6pt). All figures in the Journal will be printed in black and white technique. Coloured figures will be seen only in the PDF format on the Web address http://www.mf.unze.ba/index.php?option=com_content&view=article&id=118&Itemid=107 Tables are created with the word processing program. Each table is positioned in the desired place in the text. In the case of decimal numbers use comas (e.g. 0,253); use a small gap separating the thousands (e.g. 25.000, but not in the case of 1500). The texts under figures and table titles are in English language and in BCS for authors from ex-YU area. Section titles and titles of subsections are typed in small letters only in English language. Equations are numbered with Arabic numerals in parenthesis at the right margin of the text. In the text an equation is referenced by its number in parenthesis like "... from Eq. (3) follows ...".


234

Create equations with MS Word Equation Editor (some examples are given below).

)( 214

iiiiiii rxqxpwfwO ++== (1)

2)( 2ii

iyoE −

= (2)

( )22

2

2 nn

n

sssG

ωζωω

++= (3)

(Notice: If you convert and save your document as a MS Word 2010 file and then add equations to it, you will not be able to use previous versions of MS Word to change any of the new equations.). Figures and tables are numbered with Arabic numerals (1 ÷ n). In the text in figure or table is referenced by its number (e.g. in Fig. 1, in Tab. 1, etc.).

Slika 1. Tekst unutar formula (samo za autore sa ex-YU prostora)

Figure 1 The texts under figures (Style: Times New Roman, 11pt, Italic)

Figure 2. Simplified musculoskeletal model of an arm

(Style: Times New Roman, 11pt, Italic)

When reference to literature is made the publication number from the list of references in square brackets is used like "... in [7] the authors showed ...". In the list of references literature is cited in accordance with examples in Section. 2 COPYRIGHT TRANSFER AGREEMENT Copyright assignment. The author hereby assigns to the journal "Mašinstvo" the copyright in the above article (for U. S. government employees: to the extent transferable), throughout the world, in any form,

in any language, for the full term of copyright, effective upon acceptance for publication. Author's warranties. The author warrants that the article is original, written by stated author/s, has not been published before and it will not be submitted anywhere else for publication prior to acceptance/rejection by "Mašinstvo", contains no unlawful statements, does not infringe the rights of others, and that any necessary written permissions to quote from other sources have been obtained by the author/s. Rights of authors. Authors retain the following rights: - all proprietary rights relating to the article,

other than copyright, such as patent rights, - the right to use the substance of the article in

future own works, including lectures and books,

- the right to reproduce this article for own purposes, provided the copies are not offered for sale.

Co-authorship. If the article was prepared jointly with other authors, the signatory of this form warrants that he/she has been authorized by all co-authors to sign this agreement on their behalf, and agrees to inform his/her co-authors of the terms of this agreement.


235

Figure 3. Page setup (Style: Times New Roman, 11pt, Italic)

Figure X. Photography resolution of 300 dpi (min) (Style: Times New Roman, 11pt, Italic) 3. PUBLICATION ETHICS AND PUBLICATION MALPRACTICE STATEMENT The publication of an article in a peer reviewed journal is an essential model for our journal "Mašinstvo". It is necessary to agree upon standards of expected ethical behaviour for all parties involved in the act of publishing: the author, the journal editor, the peer reviewer and the publisher. Publication decisions. The editor of the "Mašinstvo" is responsible for deciding which of the articles submitted to the Journal should be published. The editor may be guided by the policies of the Journal's editorial board and constrained by such legal requirements as shall then be in force

regarding libel, copyright infringement and plagiarism. The editor may confer with other editors or reviewers in making this decision. Fair play. An editor at any time evaluate manuscripts for their intellectual content without regard to race, gender, sexual orientation, religious belief, ethnic origin, citizenship, or political philosophy of the authors. Confidentiality. The editor and any editorial staff must not disclose any information about a submitted manuscript to anyone other than the corresponding author, reviewers, potential reviewers, other editorial advisers, and the publisher, as appropriate. Disclosure and conflicts of interest. Unpublished materials disclosed in a submitted manuscript must not be used in an editor's own research without the express written consent of the author. Contribution to editorial decisions. Peer review assists the editor in making editorial decisions and through the editorial communications with the author may also assist the author in improving the paper. Acknowledgement of sources. Reviewers should identify relevant published work that has not been cited by the authors. Any statement that an observation, derivation, or argument had been previously reported should be accompanied by the relevant citation. A reviewer should also call to the editor's attention any substantial similarity or overlap between the manuscript under consideration and any other published paper of which they have personal knowledge.


236

Table 1. Table titles (Style: Times New Roman, 11pt, Normal)

Engineering stress σe / MPa

Engineeringplastic strain εe,pl / %

True stress σt / MPa

True plastic strain εt,pl / %

250,0 0,00 250,8 0,00 250,0 0,21 250,8 0,21 285,7 1,35 290,0 1,34 322,7 2,13 330,1 2,10 358,4 3,06 370,0 3,00 393,1 4,35 411,0 4,24 423,6 6,05 450,1 5,85 449,7 8,76 490,1 8,36 457,0 15,79 530,1 14,59 467,9 21,58 570,0 19,45 475,0 29,77 617,5 25,94

(Style in table: Times New Roman, 11pt, Normal) X. CONCLUSION Paper manuscripts, prepared in accordance with these Instructions for Authors, are to be submitted to the Editorial Board of the "Mašinstvo" journal. Manuscripts and the CD-ROM are not returned to authors. When being prepared for printing the text may undergo small alternations by the Editorial Board. Papers not prepared in accordance with these Instructions shall be returned to the first author. When there are several authors the first author is to be contacted. The Editorial Board shall accept the statements made by the first author. The author warrants that the article is original, written by stated author/s, has not been published before and it will not be submitted anywhere else for publication prior to acceptance/rejection by "Mašinstvo", contains no unlawful statements, does not infringe the rights of others, and that any necessary written permissions to quote from other sources have been obtained by the author/s.

XX. REFERENCES (Style: Times New Roman, 11pt, Normal) [1] P.E. Nikravesh, Computer-Aided Analysis

of Mechanical Systems, Prantice Hall Inc.,Englewood Cliff,NJ,1988.

[2] Gordon Robertson, Graham Caldwell, Joseph Hamill, Gary Kamen, Saunders Whittlesey: Research Methods in Biomechanics, Human Kinetics; 2nd edition, 2014.

[3] Imai, M.: KAIZEN: the key to Japan’s competitive success, Editorial CECSA, Mexico. In Spanish, 1996.

[4] Nemoto, M.: Total quality control for management. Strategies and techniques from Toyota and Toyoda Gosei, Prentice-Hall, Englewood Cliffs, NJ, 1987.

[5] Cheser, R.: The effect of Japanese KAIZEN on employee motivation in US manufacturing, Int J Org Anal 6(3):197–217, 1998.

[6] Aoki, K.: Transferring Japanese KAIZEN activities to overseas plants in China, Int J Oper Prod Manag 28(6):518–539, 2008.

[7] Tanner, C.; Roncarti, J.: KAIZEN leads to breakthroughs in responsiveness and the Shingo prize at Critikon, Natl Prod Rev 13(4):517–531, 1994.

[8] Rink, J.: Lean can save American manufacturing. Reliable plant. http://www.reliableplant.com/Read/330/lean-manufacturing-save. Accessed at 14 April 2014.

[9] SolidWorks, http://www.solidworks.com (12.5.2015)

Coresponding author: Name and surname Institution Email: [email protected] Phone: +xxx xx xxxxxx (Style: Times New Roman, 11pt, Bold)

� ��

ISSN 1512 - 5173

Godina (Volume) 14 Broj (Number) 4, Oktobar-...

Documents

Transcript of Godina (Volume) 14 Broj (Number) 4, Oktobar-...