ContentsReport for the Period 2000 to 2001 ............................................... 13

Introduction ............................................................................... 13International Contacts ............................................................... 19Research in Computer Science ................................................. 24Research in Human-Computer Interaction ............................... 27Research in Media Technology and Graphic Arts .................... 29Research in Numerical Analysis ............................................... 30Undergraduate Education.......................................................... 33Awards, Prizes and SpecialContributions Towards the Society ........................................... 37

Economy ........................................................................................ 39

History of Nada ............................................................................. 41

Ongoing Research in Computer Science ....................................... 47Computational Vision andActive Perception Laboratory, CVAP ............................................ 49

Seeing systems .......................................................................... 50Scale-space theory with applications ........................................ 52Geometric and statistical computing......................................... 54

Studies of Artificial Neural Systems, SANS ................................. 63Perception and Memory ............................................................ 65Motor Control and Behavior Selection ..................................... 67

Theoretical Computer Science, TCS ............................................. 79Approximation Algorithms ....................................................... 79Complexity and Cryptography.................................................. 81Computational Biology ............................................................. 83

Ongoing Research in Human-Computer Interaction ..................... 97Interaction and Presentation Laboratory, IPLAB .......................... 99

Computer-Supported Cooperative Work ................................ 100Collaborative Writing and Document Design ......................... 100Writing and Language Technology ......................................... 106Language Tools for Writers .................................................... 107Human-Robot Interaction ....................................................... 112Human-Robot Dialogue .......................................................... 112

Ongoing Research inMedia Technology and Graphic Arts, MEDIA ............................ 121

Media Technology and Graphic Arts ...................................... 123Graphic Arts Production ......................................................... 123Production Management In Commercial Printing .................. 123Development of Newspaper Distribution ............................... 124Learning and Interactive Media .............................................. 129Interactive Learning Environments ........................................ 129E-Commerce ........................................................................... 134

Ongoing Research in Numerical Analysis, NA ........................... 145Non-Linear PDE and Adaptive Methods ................................ 150Adaptive Numerics for Stochastic Differential Equations...... 155Computational Electromagnetics ............................................ 157GEMS ..................................................................................... 158Multi-Phase Flows .................................................................. 164Separated and Dispersed Flows .............................................. 164Computational Harmonic Analysis ......................................... 168Computational Physics ........................................................... 170Fast and Stable Algorithms for Fracture Mechanics ............... 173Large-Scale Computational Aerodynamics ............................ 177

Centres at NADA ........................................................................ 181Centre for Autonomous Systems, CAS ....................................... 183Centre for user oriented IT Design, CID ..................................... 191Parallel and Scientific Computing Institute, PSCI ...................... 199Center for Parallel Computers, PDC ........................................... 203KTH Network Operation Center, KTHNOC ............................... 205

Computing Facilities ................................................................... 207

Positions and approximate US equivalentsforskarassistent assistant professordocent associate professorlektor associate professorbitr. professor professorprofessor full professor

The cover picture: Photograph of the NADA building, taken byRickard Buch.

Photographers:Nada; page; 4, 34Clas-Göran Flinck; page; 31

Editors: Rickard Buch, Ingrid Melinder, and Caroline NordquistTypesetting and layout: Rickard BuchProof-reading: Faith ShortPrinted by: Ekblads, Västervik, May, 2002.Produced on: Apple Macintosh using Adobe® PageMaker®

AMS The Swedish Labour Market BoardAMT Advanced Media Technology LabBFR Swedish Council for Building ResearchBITS Swedish Agency for International Technical and Economical Co-operationC2M2 Center for Computational Mathematics and MechanicsCAS Centre for Autonomous SystemsCGI Centre for GeoinformaticsCID Centre for User oriented IT DesignCOMSOL Computer SolutionsCVAP Computational Vision and Active Perception LaboratoryDEC Digital EquipmentECVNet European network of excellence in computer visionESB Ericsson Saab AvionicsESTEC European Space Research and Technology CentreEURON European Robotics Research NetworkFOI The Swedish Defence Research AgencyFRN The Swedish Council for Planning and Coordination of ResearchGI Graphics InstituteHMI Human-Machine InteractionHPDR Swedish Council for high Performance ComputingHSFR Swedish Council for Research in the Humanities and Social SciencesIETF Internet Engineering Task ForceIPLAB Interaction and Presentation LaboratoryISO International Organization for StandardizationKFB Swedish Transport and Communications Research BoardKI Karolinska InstitutetKTH Royal Institute of TechnologyKTHNOC KTH Network Operations CenterKVA Swedish Academy of ScienceMEDIA Media Technology and Graphic ArtsMFR Swedish Medical Research CouncilNA Numerical AnalysisNADA Department of Numerical Analysis and Computer ScienceNFFP National Program for Aeronautics ResearchNFR Swedish Natural Science Research CouncilNGSSC National Graduate School in Scientific ComputingNORDUnet Nordic University NetworkNTM National Network in Applied MathematicsNUTEK Swedish Business Development AgencyPDC Center for Parallel ComputersPSCI Parallel and Scientific Computing Institute

RALF Swedish Council for Work Life ResearchSAGA Scientific Computation and Algebraic AbstractionsSANS Studies of Artificial Neural SystemsSBC Stockholm Bioinformatics CenterSICS Swedish Institute of Computer ScienceSIS-ITS Swedish standardization body in the IT areaSP Swedish National Testing and Research InstituteSSF Foundation for Strategic ResearchSTFI Swedish Pulp and Paper Research InstituteSTINT Swedish Foundation for International Cooperation in Research and Higher EducationSU Stockholm UniversitySUNET Swedish University NetworkTCS Theoretical Computer ScienceTDB Department of Scientific Computing, Uppsala UniversityTFR Swedish Research Council for Engineering SciencesUCLA University of California at Los AngelesUTRC United Technologies Research CenterUU Uppsala UniversityVINNOVA Swedish Agency for Innovation SystemsVISIT Visual Information TechnologyVR The Swedish Research CouncilWHO World Health Organization

Report for the period2000 to 2001

13

Ingrid Melinder

IntroductionThe department of numerical analysis and computer science, NADA,is responsible for research and education at the Royal Institute ofTechnology, KTH, and Stockholm University, SU, in the fouracademic areas of computer science, human-computer interaction,numerical analysis, and lately in media technology and graphic arts.Numerical analysis grew from applied mathematics in 1963, computerscience from information processing in 1980, and human-computerinteraction from computer science in 1998. Since July 2000, NADAhas hosted the research group in media technology and graphic arts.This publication is mainly a report for the period from 2000 to 2001.It is focused on current research, but the first chapter gives a shortoverview of the department’s total activity. We will also stress theimportance of a good computer environment in the chapter “ComputerFacilities”.

Many of NADA’s activities involve cooperation with bothacademia and industry in Sweden and many other countries, primarilyin Europe and the United States. There has been a great deal of mediaattention to the research and other activities, which culminated on 5October 2000, when five students “cracked the cipher code”, thecompetition of Cipher Challenge from The Code Book by SimonSingh. Three students won the 2001 Southwestern European Regio-nal Contest of the ACM International Collegiate Programming Con-test. Their success won the team an entry to the ACM ProgrammingContest World Finals in Honolulu, Hawaii, in March of 2002.

High-school students are the next generation university students,and it is important to stimulate their interest in science and enginee-ring. NADA contributes to this goal by giving mini-courses forteachers and students with special themes. In 2000 and 2001, NADAorganized “Sonja-Kovalevskydagarna,” where 200 mathematicallyinclined students from Sweden attended seminars for two days. Thespeakers included famous international mathematicians like JohnConway, Björn Engquist, Katheryn Hess and Benoit Mandelbrot. Oneof the interactive high points was an on-line problem-solvingcompetition between teams at schools in Göteborg, Linköping, and

NADA Report, 2000 - 2001

www.nada.kth.se

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Stockholm, and Uppsala. The Eye2Eye video technique developedby the AMT and CID laboratories within NADA enables all teams tosee and interact with all other teams. The winning team in 2000 wasFyrisskolan in Uppsala and in 2001 was Berzeliusskolan in Linkö-ping.

Graduate students bring immense value to NADA’s researchactivities; both their number and their productivity have grown con-siderably. Ten years ago we had around 50 graduate students, with 5Ph.D. and 3 Licentiate exams yearly. Now we have 100 graduatestudents; and in 2001, there were 17 presentations of doctoral thesesand 11 licentiate theses.

The establishment of the Foundation for Strategic Research,SSF, and the Swedish membership in the European Union 1995 hassignificantly changed the Swedish research funding system for sci-ence and engineering and has had a great influence on the depart-ment. Most national funding agencies, including NUTEK (now VIN-NOVA), TFR, and SSF, seem to prioritize longer-term projects withinlarger, established groups over smaller and shorter-term projects. In2001 the national funding agencies were totally reorganized. Theeffects on the research at the department are still somewhat unclear,but it is quite clear that we have to step up our efforts in attractingfunding for the further development of research themes and activitiesof research groups initiated in the favorable funding climate of thelate nineties.

PDCThe Center for Parallel Computers operates leading-edge, high-performance computers as easily accessible national resourcesprimarily for Swedish academic research and education. PDC hasserved Swedish universities since 1990 and is now a general centerfor high performance computing closely collaborating with PSCI andthe two high performance computing centres at Linköping and Umeå.The Swedish Council for Planning and Coordination of Research,FRN, renamed in 2001 the Swedish Research Council, VR, togetherwith KTH are the major sponsors. PDC has also been the Swedishand Norwegian node in a special EU Program with aim to strengthenthe small and medium sized industry in high performance computing.The program spawned many new projects and PDC parties a partnerin four other EU programs.

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In February 2001 the KTH Linux Laboratory sponsored by IBM wasopened to give users the opportunity to develop projects with opensource software. A variety of applications have been initiated, forexample in network administration, internet technology, scientificcomputing, and visualization. In the near future we expect to offer abroader set of courses initiated by KTHNOC and PDC.

PDC has invited high-school and middle-school students to learnabout high-performance computing. The staff members introducedthe students to the basic concepts of high-performance computingand also gave tours of PDC’s equipment. Ninth-Grader's Week washeld for three days in October 2000 and 2001.

TFR Basic Research ProgramsThe three basic research programs supported by TFR have contin-ued until 2001. In the new organization of the national fundingagencies we don’t know how this form of Basic Research Programswill be supported. The titles of the programs were: algorithms andcomplexity at TCS, computational vision and active perception atCVAP, and mathematical and numerical study of continuum mechanicsat NA.

The report “Computer science in Sweden: An internationalevaluation of the research supported by TFR, December 1999”discusses the three research groups at NADA.

CVAP: “This group is one of the top 5 in Europe in computervision... It has the vision of the field, it has the ideal combinationbetween theoretical and experimental work, and it is truly in a leadingposition to chart the waters of research in Computer Vision area. Thegroup is well plugged in with European and world groups in thisarea.”

SANS: “The group clearly knows what they are doing... Thegroup seemingly has the largest neural simulator in the world, with50,000 neurons, and 4.5 million synapses. This is very impressive.”

TCS: “This group is justifiably proud of its international repu-tation, due in large measure to the awards and famous results ofProfesspr Håstad... a well-integrated, and intellectually powerfulactivity. Especially important, the committee believes, is the outreacheffort that the group has made in areas such as bioinformatics, datamining, and text-processing ... the pattern of organization is close towhat we would see as an ideal model for a basic research-orientedgroup...”

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Vinnova Competence CentresVINNOVA, formerly NUTEK, supports around 30 competence cen-ters at Swedish universities. Their mission is to be focal points for anumber of key research areas, increase the contact between universityand industry, and produce more industry-compatible researchers. Thetwo centers hosted by NADA are Center for User oriented IT Design,CID, and the Parallel and Scientific Computing Institute, PSCI. InMarch 2000 the Nutek report from second, Mid-Term InternationalEvaluation become official and the funding was prolonged for an-other tree years. We quote some General Conclusions from the expertsbelow.

The focus of the research at CID is on design and study of new,usable, and aesthetically pleasing interactive IT applications forcommunication and cooperation, at work, and in daily life. There are19 partners from Swedish companies, governmental agencies, unionorganizations, and there are about 15 Ph.D. Students. The expertswrote: “CID has established an exciting research programme in UserOriented HCI-Design. It is well recognized as a resource in this areaby Swedish industry. Its research is also internationally recognizedas in evi-dent by publications and demonstrations in leadingconferences. This needs to be augmented by developing better waysto communicate the conclusions and messages of the Center´s re-search to the general user and technical communities outside itsdomain of expertise.”

The aim for PSCI is to be the glue between Swedish industryand academia, represented by NADA at KTH and TDB at UppsalaUniversity. PSCI is a neutral place for 18 industrial partners to meetand discuss problems in scientific and high-performance computingand there are currently around 15 Ph.D. Students.

The experts wrote: “PSCI is nicely maturing into an excellentCompetence Centre, in an area that is of critical significance to severalsectors of Swedish industry. The collaboration with industry in re-search and education is impressive, The basic research conducted isfirst class, with element of uniquely innovative and promising ideas.

The creation of the new international MSc program in scientificcomputing and of new examinations in this area in the KTH excellentand commendable educational activity. PSCI is clearly an asset forSweden and among the very best such Centers in the world.”

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SSF CentresThe Foundation for Strategic Research, SSF supports research cen-ters in areas of strategic importance for Sweden. The focus is on long-term knowledge build-up and basic research, with the object to fore-see and activate important research areas to create innovative industrialproducts for the future.

The Centre for Autonomous System, CAS is hosted at NADAwith participation from four KTH groups, namely Computational Vi-sion and Active Perception; Machine Elements - Mechatronics andMachine Design; Signals, Sensors and Systems for Control; andOptimization and Systems Theory. The research deals withautonomous robot systems and the aim is to build intelligent servicerobot systems. Specifically, systems for cleaning, basic transportationin manufacturing environments and/or surveillance in an indoor set-ting are studied and prototyped. As a result of the collaboration withElectrolux, the researchers at CAS have taken out a patent in relationto the navigation system now used in the world’s first automaticvacuum cleaner named Trilobite.

The center has been evaluated several times in connection toapplication to the EU union and the Swedish Strategic Foundation,SSF. We quote the review committee from the evaluators’ report onthe proposals for swedish strategic foundation’s neuroscience-computer science robotics research center (NCRC) initiative: “Therobotics group at KTH and their Centre for Autonomous Systems(CAS) is an excellent resource for verifying neuro-computationalmodels and for building robots that utilize and interact with biologicalsystems. In addition the robotics group is a point of contact withindustrial activity in service robotics, prostheses, micro/nano robotsfor medical applications. There is an expectation of various spin-offtechnologies from the center being commercialized.” We also quotethe report concerning the SANS group: “The goals here are to developmathematical modeling and simulation tools from the individual ionchannel and intracellular biochemical network to distributed networks.The goal is to determine robust fault tolerant architectures based onstochastic, low precision computing mechanisms. The idea of usinglow precision stochastic computing mechanisms is instantiated in anumber of ’test bed’ applications: multi-functional mobile robots, the’living factory’, and a network management system application. Thisis a very interesting and innovative new direction of investigation.”

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A graduate school has been set up in association with the center. Morethan 20 Ph.D. students have been enrolled and around 10 MSc studentsannually complete their diploma theses at CAS. Five Ph.D. and oneLicentiate degree within the graduate school have been examinedduring 2000 to 2001.

Late 1999 the Stockholm Bioinformatics Center, SBC, was esta-blished for a period of at least five years. It is hosted at the depart-ment of Biochemistry at Stockholm University. One of the initiatorsis docent Jens Lagergren at NADA, who also is one of the associateprofessors at the center. In July 2001 Jesper Tegnér was appointedForskarassistent at SBC, which also employs researchers from Karo-linska Institutet, KI. The aim of SBC is to provide a critical mass ofexpertise in bioinformatics and computer science for high-level re-search, methods development, and ad-vanced postgraduate training.

KTHNOC and AMTIn 1998 the KTH Network Operating Centre, KTHNOC, was esta-blished as a national resource center with a responsibility to run cen-tral nodes including the Swedish University Network, SUNET, andNordic Academic Networks, NORDUNET. The KTHNOC service isdesignated to network service providers, not for end users. We havejust started to build up academic activities and plan to collaboratewith the departments at KTH, IT University and Blekinge Institute ofTechnology.

NADA has also hosted a local advanced media technologylaboratory, KTH AMT, in close connection to the research groupsMEDIA and CID. Here our aim is to educate and support both studentsand teachers.

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International ContactsThe research groups have been very successful in organizing andcollaborate with researchers from other countries within projectssponsored by the European Community. In the period covered in thisreport we have been coordinator in 7 and participated in 24 otherEuropean cooperative programs. The programs are listed below.

CAS is the coordinator of• COGVIS: Cognitive Vision Systems; EU (Information Technology

– IST)• EURON: European Robotics Research Network, Future and

Emerging Technologies Program under DG–INFSOC;EU (Information Technology – IST)

and takes part in• CAMERA: CAD Modeling of Environments from Range Data

Analysis; EU (Training and Mobility Research Program – TMR)

CID is the coordinator of• eRENA: electronic arenas for culture, performance, art and

entertainment (Information technologies – ESPRIT Long-TermResearch Project)

• interLiving: designing interactive, intergenerational interfacesfor living together; EU (Information Technology – IST)

• SHAPE: Situating Hybrid Assemblies in Public Environments; EUInformation Technology – IST)

and takes part in• KidStory: developing collaborative storytelling environments for

children, with children; ESPRIT

CVAP is the coordinator of• VIBES: Video Browsing Exploration and Structuring; EU

(Information Technology – IST)

We have participated in 31European cooperative pro-grams and been coordinatorin 7 of them.

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and takes part in• Figure-Ground Segmentation from Multiple Cue in Active

Vision Systems; EU (Marie Curie Research Training and MobilityResearch Program – TMR)

• IMPROOFS: Image Processing Operations for Forensic Support;EU (Information technologies – ESPRIT)

• INSIGHT2+; EU (Information Technology – IST)• VIRGO: Vision-based Robot Navigation Research Network; EU

(Training and Mobility Research Program – TMR)

MEDIA takes part in• ADEPT: Advertising in electronic publishing; Leonardo da Vinci

project• ADIS: Integration of Adults with Disabilities into the Labour

Market through Open and Distance Learning; EU Socrates/Minervaproject

• RESCUE: The Re-Naissance Economy: Strategies andCoordination for Europe; EU (Information Technology – IST)

The NA group takes part in• Hyperbolic Systems of Conservation Laws; EU (Training and Mobil-ity Research Program – TMR)

PDCJanuary 1997 to April 2000, the Swedish HPCN Technology Trans-fer Node, PDCTTN, participated in the European HPCN TechnologyTransfer Node Network (High-Performance Computing andNetworking – ESPRIT) and coordinated six TTN projects withindustry.• SIMMILL: Simulation in pulp mills• IDASTAR: IDA – a distributed simulation tool for the building

industry• OPTIBLADE: fan blade shape optimization by parametric CFD• OPTIMOM: high-performance computing in plastic industry for

optimization of Injection• 3DEMO: 3D-photo modeling including 3-D animations with parallel

computing for architects and the buildingindustry

• VIDEOGRAPH: parallelization of video graphic effects

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PDC also takes part in• ENScube: European Numerical Simulation Services for SMEs

Feasibility/Validation Project• Neurogenerator: database generator for the neuroimaging

community• SEP-Tools: interoperable suite of European HPCN tools; EU

(the ESPRIT EP project)• VIRTUALFIRES: Virtual Real Time Fire Simulator; EU

(Information Technology – IST)

PSCI takes part in three ESPRIT RTD programs• EMCP2: Electro-Magnetic Compatibility Using Parallel

Parametrization, (Information Technologies)• MPACT: Inverse Methods for wave Propagation AppliCations in

Time domains, (High-Performance Computing and Networking)• JACO3: JAva- and COrba-based COllaborative environment for

COupled simulations (Information Technologies)

and in• Viscosity Solutions and Their Applications; EU

(Training and Mobility Research Program – TMR)

SANS takes part in• Microcircuits: Cortical, Cerebellar, and Spinal Neural Networks –

Towards an Interface of Computational and Experimental analysis;EU (Life program – Biotechnology)

Conferences, Workshops, and Exhibitions• PLEXUS, exhibition at the Museum of Science and Technology in

Stockholm, 9 March 2000, CID participated with “Urmänniskanmöter Superman,” “Kidstory,” and “Mirror to the next millenium.”

• CyberMath is presented in SIGGRAPH 2000, New Orleans,23-28 July 2000, CID

• NGSSC Summer School: Introduction to High PerformanceComputing at PDC, 21/8-1/9 2000, PDC

• Desert Rain, exhibition, 11-12/ September 2001, CID incollaboration with the performance group Blast Theory, Universityof Nottingham; and Center for Art and Media Technology, Karls-ruhe

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• Brainstorming on Intelligent Environments and Robotics,18-19 September 2000, CAS

• NordiCHI 2000, the first Nordic conference on human-computerinteraction, 23-25 October 2000, IPLAB and CID

• NWChem/ECCE Workshop, 19-20 October 2000, PDC• Niornas vecka (Ninth-Graders’ Week): the basics of

high-performance computing at PDC, 18-20 October2000, PDC• Simulation and Visualization in the Life Sciences: PDC Annual

Conference 2000,14-15 December 2000, PDC• Workshop in computational electromagnetics, 4-5 December 2000,

PSCI• Expedition Rymden, exhibition in the Swedish Museum of

Natural History, 4 January 2001, CID• Temadag, Lärmiljöer och tillgänglighet , 17 January 2001, CID• Linux Lab Inauguration, 13 February 2001, PDC• Smarta tjejer: smarta grejer in the Museum of Science and

Technology in Stockholm, 10 March 2001, CID participate• Workshop on multiple view geometry, 22 March 2001, CVAP• Workshop on Human interaction with mobile robots: an

interdisciplinary research challenge, 30 March 2001, CAS andIPLAB

• Connect 2001, IT exhibition, Stockholmsmässan 23-25 April 2001,CID participate with two the two expeditions Rymden (Space) andGestbaserad interaktion (Gesture Based Interaction).

• Stockholm Workshop on Computational Neuroscience, 1-3 June2001, SANS together with KI

• STAR TAP Annual Meeting at INET, 5 June 2001, PDC• HMI Summer School; The Disappearing Computer, 13-19 June 2001,

CID• EU Disappearing Computer Conference, 20-21 June 2001, CID• The 9th Stockholm Workshop on Computer Vision, Rosenön,

30 July-2 August 2001, CVAP• NGSSC Summer School; Introduction to High Performance

Computing at PDC, 22-31 August 2001, PDC• PSCI annual meeting, 13-14 September 2001, PSCI• CAVE Programming Workshop, 1-4 October 2001, PDC• Niornas vecka (Ninth-Graders’ Week): The Basics of

High-Performance Computing at PDC, 23-25 October 2001, PDC

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• 10th ABC meeting in computational biology and chemistry,13 December 2001, PDC

• Urmänniskan möter Superman, seminar and exhibition,14 December 2001, CID

Visitors and Other Scientific ExchangeProfessor Björn Engquist works part-time at NADA, KTH; UCLA,California; and Princeton University, New Jersey. In October 2000Lennart Johnsson was appointed professor in Applied NumericalAnalysis at KTH. He is also a part-time professor at the University ofHouston.

Olof Runborg held a post-doctoral position at Princeton Uni-versity, US, from October 1999 to September 2001, and Anna-KarinTornberg has had a post-doctoral position at Courant Institute in NewYork since September 2001. They have both been appointed “Fors-karassistent” at NADA since autumn 2001.

Professor Jesper Oppelstrup has a sabbatical year, September2001 to July 2002, at the United Technologies Research Center, UTRC,Hartford Connecticut.

These arrangements give faculty members and Ph.D. studentsin numerical analysis the opportunity to work at research groups inthe United States for periods of several months.

John Bowers, University of Manchester,has been a part-timeguest professor at IPLAB since 1996. He supervises several Ph.D.students and was deeply involved in the summer school “TheDisappearing Computer” within the HMI Program.

Danny Roobaert, Katholieke Universiteit Leuven, Belgium, wasa Marie Curie research fellow at CVAP from 1997 to 2001. Hepresented his Ph.D. thesis on 31 May 2001.

Georgious Zouraris, University of Crete, held a post-doctoralposition at the NA group from 1997 to 2001 sponsored by EU – TMRproject “Hyperbolic systems of conservation laws.”

Allison Druin, Assistant Professor at the University of Mary-land, has worked within the KidStory project at CID for 2.5 months ayear since 1998.

Alexander Kozlov, University of Nizhny Novgorod, Russia, hasheld a post-doctoral position at SANS since October 1998, sponsoredby the Russian Ministry of High Education.

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Kestutis Andrasiunas, Professor at Vilnius Academy of Art, was aguest professor at MEDIA research group in 2000.

Eric Hayman started January 2001 as a Marie Curie ResearchFellow with CVAP. Previously he was at the Active Vision Laboratoryin the Robotics Research Group at the University of Oxford.

Örjan Ekeberg is on sabbatical as an invited research Fellow2001/2002 at the Institute for Advanced Study in Berlin, Germanyfrom September 2001 to July 2002.

Dr Shumin Zhai, research scientist at the IBM Almaden Re-search Center in San Jose, California, spent his sabbatical semesteras a visiting professor at IPLAB from September to December 2001.

Shorter visits take place all the time. These are summarized inthe tables at the end of this section.

Research in Computer ScienceThe research in computer science is performed within three large andindependent research groups related to algorithms and complexity,computer vision and robotics, and artificial neural systems. A moredetailed information can be found in separate chapters in this report.

Viggo Kann and Tony Lindeberg were promoted to Professorin 2000.

Professor Johan Håstad was elected a member of KungligaVetenskapsakademin, KVA, (Swedish Academy of Science) in 2001,and Tony Lindeberg was appointed a KVA Research Fellow.

Hercules Dalianis, Henrik Eriksson and Mikael Goldmann wereappointed Docent in 2001.

Olle Bälter was appointed Lektor in 2000 while Lars Eng-ebretsen and Jesper Tegnér were appointed Forskarassistenter in 2001.Lars Engebretsen also was awarded the Werthén prize to be able tocontinue his research as a post-doctoral fellow 2000-2001 at MIT, inBoston.

Ph.D. and Licentiate Theses are listed within the relevant re-search group.

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CVAP: Computational Visionand Active Perception LaboratoryThe CVAP group, started in 1982, performs research in computervision and robotics, as well as on related problems in geometricmodeling and computations. The scientific leaders are professors Hen-rik I. Christensen, Jan-Olof Eklundh, Tony Lindeberg and docent Ste-fan Carlsson.

Different areas of study are:• Seeing systems e.g., computational vision in the embodiment of

seeing robots and in conjunction with behaviors of mobility andmanipulation.

• Scale-space theory with applications: for example, fingerprintanalysis, steel quality inspection, and tracing and recognizing handgestures.

• Geometric and statistical computing where the central problem isthe establishment of correspondence between images from diffe-rent viewpoints.

This research deals with autonomous robot systems within CAS incollaboration with three other departments at KTH. The aim is tobuild intelligent service robot systems. Specifically, systems forcleaning, basic transportation in manufacturing environments, and/or sur-veillance in an indoor setting are studied and prototyped. As aresult of the collaboration with Electrolux, the researchers at CAShave taken out a patent in relation to the navigation system of thevacuum cleaner. This system is now used in the world’s first automaticvacuum cleaner, named Trilobite.

Ph.D. Theses:• Kristian T. Simsarian, 30 March 2000, Toward Human-Robot

Collaboration• David Nistér, 23 March 2001, Automatic Dense Reconstruction

fromUncalibrated Video Sequences• Danny Roobaert, 31 May 2001, Pedagogical Support Vector

Learning:a Pure Learning Approach to Object Recognition• Danica Kragic, 14 June 2001, Visual Servoing for Manipulation:

Robustness and Integration Issues• Hedvig Sidenbladh, 2 November 2001, Probabilistic Tracking and

Recognition of 3D Human Motion in Monocular Video Sequences

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SANS: Studies in Artificial Neural SystemsThe SANS group, headed by professor Anders Lansner, was formedin 1987 with research activities spanning from artificial neural networkand neuro-computing to biological modeling of neural systems in closecollaboration with scientists at KI’s department of neuroscience, andwith research groups at SICS.

The research focuses on theoretical and computational neuro-science, i. e., mathematical modeling and computer simulation ofbiological nervous systems, the brain in particular. The primary aimis to improve the understanding of the principles underlying theirinformation processing capabilities. The models extend from thoseincorporating biological details of cellular processes, neurons, andneural networks to abstract connectionist type models, and artificialneural networks and systems. The SANS group also emphasizes theengineering and applications aspects of understanding biological in-formation processing to import the knowledge in the design ofadvanced technical systems.

TCS: Theory in Computer ScienceThe theory group now headed by professors Stefan Arnborg, JohanHåstad, and Viggo Kann started in 1982 exploring topics originatingin applications-oriented work. The objective of the research is toinvestigate methods of efficient computation in mathematically precisesense, and to find lower bounds on the computational resourcesrequired for a computation.

The types of computations studied are either chosen for theirtractability or for their importance in practical applications. Someareas of study are approximation algorithms, complexity andcryptography, decomposability, formal methods, computationalbiology, algorithms in language engineering, design and architectureof brain image database managers, inference from data, and decisionsupport.

TCS also hosts some projects carried out under the auspices ofCGI, the Centre for Geoinformatics. These deal with intelligent dataanalysis and visualization, and database languages for spatial analy-sis. CGI, which is a cross-disciplinary competence center, involvingseveral departments from KTH, SU and FOI, will be reorganizedduring the academic year 2001/2002.

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Ph.D. Theses• Lars Arvestad, 27 January 2000, Algorithms for Biological Sequence

Alignment• Lars Engebretsen, 25 April 2000, Approximate Constraint

Satisfaction• Gunnar Andersson, 26 May 2000, Some New Randomized

Approximation Algorithms• Lars Ivansson, 17 November 2000, Computational Aspects of

Radiation Hybrid Mapping• Öjvind Johansson, 29 September 2001, Graph Decomposition Using

Node Labels

Lic Thesis• Karim Oukbir, 11 June 2001, Database Query Language for

Uncertain Spatial Data

Research in Human-Computer InteractionThe research in Human-Computer Interaction, HCI, has been perfor-med within the computer science area until 1998, when HCI was esta-blished as a new academic discipline at KTH.

In 2000 Per-Anders Forstorp was appointed Lektor in Comm-unication; in 2001 Henrik Artman and Ann Lantz were appointedLektor while Tessy Cerratto was appointed Forskarassistent in Hu-man-Computer Interaction, and Ann Lantz was appointed Docent.

IPLAB: Interaction and Presentation LaboratoryIPLAB was established in 1985 as an interdisciplinary group withresearchers from computer science, linguistics, psychology, sociology,and design with professors Kerstin Severinson-Eklundh and YngveSundblad as research leaders. The group focuses on human-computerinteraction aspects of design and development projects.

Central themes for the research are computer-supported co-operative work, computer-supported writing and language technology,user-centered system development, and human-robot interaction.

Since 1997, IPLAB has been engaged in the build-up of thegraduate school in HMI, funded by SSF in collaboration with theUniversity of Linköping.

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IPLAB is closely related to the Centre for User Oriented IT Design,CID, and also collaborates with the Centre for Autonomous Systems,CAS. You will find information on these centers in a separate chapter.

The first Nordic conference on human-computer interaction,NordiCHI 2000, was hosted by IPLAB and CID and took place inOctober 2000.

The NADA research team with Hercules Dalianis, Johan Carl-berger, Martin Hassel, and Ola Knutsson has developed SweSum,Automatic text summarization of Swedish, English, Spanish, French,and German. It was nominated for the prize “Guldmusen” 2001. Theprize was founded in 1996 to award Swedish research projects withinInformation Technology. Euroling AB is a spin-off company fromNADA started by the team to exploit their theoretical developments.The aim is to develop human language technology and in November15 Euroling AB was nominated Spin-off Company of the Year 2001by the Swedish Academy of Engineering Science and CONNECTSweden.

Ph.D. Theses• Björn Eiderbäck, 23 January 2001, Object-Oriented Frameworks

with Design Patterns for Building Distributed Information Sharing• Konrad Tollmar, 12 October 2001, Towards CSCW Design in the

Scandinavian Tradition• Hee Cheol (Ezra) Kim, 2 November 2001, Computer Support for

Collaborative Reviewing of Documents

Lic Theses• Ann Fatton, 5 October 2000, Design and Evaluation of a Page-Based

Writing Environment• Anders Hedman, 21 February 2001, Visitor Orientation: Human-

Computer Interaction in Digital Places• Ola Knutsson, 8 March 2001, Automatisk språkgranskning av svensk

text• Henrry Rodriguez, 7/6 2001, Using the WWW as Infrastructure for

Collaborative Production of Documents• Fredrik Winberg, 12/12 2001, Auditory Direct Manipulation for Blind

Computer Users

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Research in Media Technology and Graphic ArtsThe research group for Media Technology and Graphics Arts is headedby professors Nils Enlund and Roger Wallis. The group moved fromthe department of Manufacturing Systems to NADA during areorganization at KTH in July 2000. The group collaborates closelywith industry and is concerned with research in technology andmethods that support human communication over distance in timeand space. The focus is within three areas.• Business development in the media industry, i.e., the influence of

new technology on media business and industry developments.• Digital Media, i.e., the technology and methods supporting printed

communication.• Graphic arts production, i.e., the design and use of new digital

communication media.

Professor Nils Enlund was elected a member of the Swedish Aca-demy of Verbovisual Information in 2001.

A multidisciplinary research seminar course, “Media World2020,” has been arranged during the academic years 1999-2000, 2000-2001, and 2001-2002. This is a cooperation between the departmentof Journalism, Media, and Communication at Stockholm University,the department of Information Science at Uppsala University, the de-partment of Information technology and Media at Mid-Sweden Uni-versity, and the NADA Media Technology and Graphic Art ResearchGroup.

A multidisciplinary research seminar course, “Art and NewMedia,” has been initiated in 2001, with support from the ScienceFoundation, as a joint project between the Royal College of Fine Art,KI, Södertörn University College, and NADA.

Ph.D. Theses• Panagiota Koulouvari, 23 March 2001, Organizational Learning in

Dynamic Environments - Case Studies from the Media Industry• Alex Jonsson, 30 March 2001, Enhancing Workflows in On-Line

Information Sharing Systems• Kristina Sabelström Möller, 4 May 2001, Information Categories

and Editorial Processes in Multiple Channel Publishing• Christian Persson, 14 December 2001, Strategies for enhancing

consumer interaction in electronic retailing

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Lic Theses• Jonas Rehn, 7 December 2001, Information Flow and Physical

Distribution• Anastasios E. Politis, 13 December 2001, Human Resource

Management Strategies within the Graphic Arts and Media Sector• Maria Enroth, 13 December 2001, Tools for Eco-Efficiency in the

Printing Industry

Research in Numerical AnalysisThe research in Numerical Analysis is closely integrated with theParallel and Scientific Computing Institute, PSCI, and with the Cen-ter for Parallel Computers, PDC. Professors Björn Engquist, AndersSzepessy, and Jesper Oppelstrup head the research. Focus is on diffe-rential equations, and the activities cover the spectrum from analysisand theory of mathematical models via development of algorithms toimplementation on computers, especially within fluid mechanics,electromagnetic wave propagation, and materials science. Thetheoretical emphasis is on analysis and numerical approximation ofnon-linear conservation laws, wave propagation models, and problemswith several scales. Professors Lennart Johnsson and Axel Ruhe havebeen appointed to the department recently, and we expect that theresearch focus will broaden in the near future.

The applications are pursued in cooperation with researchersfrom other disciplines, from academia, and from industry. Compu-tational fluid dynamics is a mature interdisciplinary application, andcollaboration with the departments of Aeronautics and Mechanicsstrengthens our efforts in this area. The most prominent current non-aerodynamic applications are electromagnetic and elastic wavepropagation, in non-Newtonian flow, and chemical processes such ascombustion. In cooperation with industry, a major software systemfor computational electromagnetics is under development with newhybrid algorithms for both time and frequency domains

The numerical algorithms devised for the various classes ofproblems must be adapted to high-performance parallel computers.The PDE problems are now commonly parallelized – both for work-station clusters and dedicated parallel computers – by spatial domaincomposition and standard message-passing libraries.

We have strong contacts with the Department of Mathematicsat KTH, and professors Jan-Olof Strömberg and Anders Szepessy are

31

sharing their time between the departments. Especially within PSCI,we work very closely with the research group in scientific computing,TDB, at Uppsala University.

Introduction to High-Performance Computing was a course thatran from August 21 to September 1 2000 with 73 participants, andfrom August 20 to 31 2001 with 39 participants from most universitiesin Sweden. The course is within the National Graduate School inScientific Computing, NGSSC, funded by SSF.

The KTH International Master’s Program Scientific Computing,hosted by the department since fall 1998 creates lively interactionwith the research groups. The students carry out examination projects,and the researchers are strongly involved in curriculum developmentand teaching.

Lennart Johnsson was appointed professor in applied NumericalAnalysis in October 2000. Axel Ruhe was appointed guest professorin Numerical Analysis in November 2001. He was appointed full pro-fessor in January 2002. Until recently he was a professor at ChalmersUniversity in Göteborg, Sweden.

Anna-Karin Tornberg was awarded the Werthén-prize 2001 tobe able to continue her research as post-doctoral fellow at CourantInstitute, New York. Anna-Karin also was awarded the First LeslieFox Prize in Numerical Analysis in a prize ceremony on June 222001 at Oxford University Computing Laboratory.

In 2001 Olof Runborg and Anna-Karin Tornberg were appointedForskarassistent.

Awardwinner of the Werthén prize 2001 Anna-Karin Tornberg

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Ph.D. Theses• Anna-Karin Tornberg, 5 December 2000, Interface Tracing Methods

with Application to Multiphase Flows• Ulf Andersson, 9 March 2001, Time-Domain Methods for the

Maxwell Equations• Gunnar Ledfelt, 30 March 2001, Hybrid Time-Domain Methods

and Wire Models for Computational Electromagnetics• Sergei Simdyankin, 11/6 2001, Computer Simulation of

Condensed Phases with Icosahedral Local Order• Patrik Skogquist, 5 October 2001, High-Order Adaptive Difference

Methods for Combustible Flows• Mattias Liefvendahl, 2 November 2001, Stability Results for Viscous

Shock Waves and Plane Couette Flow

Lic Theses• Christian Wauquiez, 15 February 2000, Shape Optimization of Low-

Speed Airfoils Using MATLAB and Automatic Differentiation• Petter Kolm, 6 April 2000, Quadruple and Octuple Layer Potentials

in Two Dimensions• Christer Andersson,16 June 2000, Numerical Simulation of Dendritic

Solidification Using a Phase Field Model• Duccio Fanelli, 16 October 2000, On the Dynamics of

Self-Gravitating Systems and a New Interpretation of the ResonanceTheory for Betatron Motion

• Raul Tempone, 12 December 2000, Weak Approximation of ItoStochastic Differential Equations and Related Adaptive Algorithms

• Joakim Möller, 6 June 2001, Studies of Recursive Projection Methodsfor Convergence Acceleration of Steady-State Calculations

• Kyoung-Sook Moon, 7 December 2001, Convergence Rates ofAdaptive Algorithms for Deterministic and Stochastic DifferentialEquations

• Malin Siklosi, 18 December 2001, Two Aspects of Viscous Shocks:Existence of a Solution and Numerical Errors

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Undergraduate EducationThe department is responsible for the undergraduate training inComputer Science, Human-Computer Interaction, Media Technologyand Graphic Arts, and in Numerical Analysis in Stockholm; the de-partment offers around 100 different courses for more than 7 000participants. NADA gives numerous courses for 13 of the 14 schoolsin Master of Science in Engineering at KTH, and also provides cour-ses for continuing education. The most advanced courses typicallyattract students from the programs in computer science, engineeringphysics and media technology. The university courses are given inthe programs in computer science, mathematics, and physics, and asa number of special courses.

The National Agency for Higher Education has evaluated theeducation in computer science at 12 departments in Swedish uni-versities. NADA was ranked one of the top three, and the commentswere very positive about both the undergraduate and graduateeducation. The committee recommended the department to improveand give a more precise formulation of the vision and the goals; topay more attention to introducing the first year students with theirvery different knowledge in mathematics.

There has been a similar evaluation in mathematics with 22departments, including NADA, within the area of numerical analy-sis. The report will be released in March 2002.

1988/89 1992/93 1996/97 1998 2000 2001

TRITA-NA-research reports 20 63 49 54 37 67

Master thesis 30 39 57 63 84 118

Publications 35 131 – 108 126 120

Seminars 75 74 120 114 103 115

Lectures abroad 35 86 – 86

Graduate courses 10 10 10 13 13 43

Research students 35 58 69 76 79 101

Doctoral degrees 2 9 8 3 6 17

Licentiate degrees 2 3 5 7 6 11

Foreign guests 30 32 46 69 39 51

Foreign guest months 30 74 100 65 48 51

Months visiting abroad 25 69 80 23* 58 69

*1998 we only counted visits one month or longer

Some figures about research at Nada.

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Curricula, courses, and programs for teaching, learning, and exami-nation are continually reviewed and developed. A tutorial system forthe School of Computer Science is under discussion, and the pro-blem-based learning system for the School of Surveying is now alsopracticed for other courses.

The undergraduate course “Robotics and Autonomous Systems”taught by Ph.D. student Mattias Bratt is concluded by a table hockeycompetition between the LEGO robots constructed by the courseparticipants. This form of examination is quite entertaining and prizedby both the creative designers and the visitors. The winning team2000 was Andreas Berndt, Johnny Bigert, and Marcus Marcussonwith their robot “Hink” (Swedish for “bucket”) and the 2001 winningteam was Karl Danielsson, Gunnar Elvers, and Björn Jacobsson withtheir robot “Kakmonstret” ( Swedish for The Cookiemonster).

The aim of the undergraduate course “User-Centered Program De-velopment” taught by Docent Ann Lantz is to give students theknowledge to design and implement a project idea in cooperationwith users and designers with other competencies. The projects havea theme, and in 2001 it was “physical activities for good and for fun.”One team is usually a collaboration of six students from differentschools. One of the winning projects was “JoyStep”. Here four plateswere placed on the floor in front of a screen and the children coulduse them as a joystick for television. All projects are demonstratedfor an audience of almost a hundred from both academia andcompanies.

The aim of the undergraduate course “Program DevelopmentProject” for the students in Computer Science and in EngineeringPhysics taught by Lektor Lars Kjelldahl, is to give students the ex-perience of designing and implementing a large computer applicationin cooperation with 5 other students and with users. This course willprepare the students for similar tasks in their future professional lifvesand the projects are presented to an audience of avout 100 people

The awardwinning robot:The Cookiemonster

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with demonstrations of the prototypes. The most prominent projectsin 2001 were “Network-based strategy game for research proposal,Gecco” in collaboration with NADA; “Digital broadcasting appli-cation” in collaboration with the national television network SVT;and “Interfaces and services for embedded screens in homes, homesolutions” in collaboration with the Swedish Institute of ComputerScience, SICS. Among the year 2000 entries, special mention goes to“Milochronos, a computer program which gives an individual toolsto schedule, plan, and remind” in collaboration with Hjälpinstitutet;and “FairWay, Navigation system for visitors at exhibitions” in collab-oration with AMT/KTH.

During the years 2000 and 2001 some special installations thatwere based in performance research have been arranged as studentprojects in Media Technology produced by Lektor Leif Handberg withart and technical support by Claus Knudsen, Mats Erixon, and AMT.• “From atoms to bits”: student project presentation in May 2000

about pioneer spirit and early nuclear research. Modern mediatechnology presented in an old research environment – the originalroom for R1, the first nuclear reactor in Sweden, now becoming theKTH Experimental Performance Space.

• “Communicative spaces”: Stockholm Academic Forum and KTHin October 2000. This was a public field study with a continuousvideo loop between two locations in Stockholm. Here people in twogeographical places could interact in a common virtual room, and asmall universe opened when the video loop was broken.

• “A wireless night”, Stockholm City Hall in March 2001. A publicfield study was performed as a part of a European Union meetingdinner party. The communicative spaces were used to add extra valueto the entertainment.

• Introduction to a seminar with Polar Music Price winner RobertMoog in May 2001. The reactor room was used for a zoom-outfrom Mr. Moog and his instrument, symbolizing technology’s rolein developing new kinds of music and spreading it throughout theworld.• WGLN Workshop on Performance, June 2001. Performance-basedlecture in the reactor room with the mathematician Ambjörn Naeveusing large projections on the walls.

More documentation about these installations can be found atthe site of R1:< www.r1.kth.se>

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We have recently started a fruitful collaboration between the under-graduate education and the department of Mechanics. The first twocourses are planned and given in the academic year 2001-2002 byprofessor Dan Henningson (department of Mechanics) and Ph.D. stu-dent Katarina Gustavsson (NADA). It is a comprehensive two-partcourse on theory and practice of computational fluid dynamics, CFD,where students with different background are accommodated by dif-ferent sets of introductory lectures. The enrollment has grown steadily,and the collaboration will be continued. Other application areas, forexample in physics and chemistry, will be investigated with an eyetoward developing joint courses with similar formats. Since thebeginning of the 1980s, we have collaborated with the Department ofMathematics and have given courses in mathematical modeling andapplications.

In 1997 we started an international Master’s program inscientific computing. The number of annually enrolled students witha B.Sc. degree in mathematics has grown from 10 to 20. The programhas been very successful and attracts many applicants annually fromall over the world. In 2001, 22 students were chosen from 117applicants; and since the program started, the students have comefrom 18 countries, mostly from Europe and Asia.

PDC arranges and teaches the annual Summer School"Introduction to High-Performance Computing" which is now also acourse in the National Graduate School in Scientific Computing.

The comprehensive programs are rounded off by a master the-sis requiring about one semester of work. The number of completedtheses presented at NADA has grown rapidly in the last years; 118were presented in 2001. Most projects are carried out in industry, afew at the department or abroad, and every student’s main supervisoris a teacher at NADA.

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Awards, Prizes, and SpecialContributions Towards the SocietyA NADA/KTH-supported team made up of students Fredrik Niemelä(School of Computer Science), David Rydh (School of EngineeringPhysics), and Mattias de Zalenski (University of Cambridge, Eng-land) was the winning team in the 2001 Southwestern European Re-gional Contest. They solved one more problem than the teams ofEcole_Polytechnique, France; and Roma Sapienza1, Italy. In March2002, the winners will go to The 26th Annual ACM InternationalCollegiate Programming Contest World Finals in Honolulu, Hawaii.

In honor of Gerd Eriksson on her 60th birthday, the Gerd Eriks-son prize was founded in September 2001 by the department torecognize a young teaching assistant at NADA. Gerd is a seniorlecturer at NADA and has been awarded many prizes at KTH for herprominent contributions to undergraduate education. The first reci-pient of the Gerd Eriksson prize of 2001 was Vahid Mosavat.

Students in different schools at KTH have selected theircandidates for the best teacher of the year. Three lecturers at NADAwere honored: Gerd Eriksson, 2000, by the School of Computer Sci-ence and Engineering, Ninni Carlsund, 2000 and Henrik Eriksson,2001, by the School of Engineering and Business Management. Hen-rik was also awarded the prize of Ångpanneföreningen for being thebest distributor of technique knowledge in 2001.

Olof Lindholm was awarded the 2000 FRAMFAB (formerGuide) prize, given to students at the School of Computer Science atKTH, for his master thesis “Gene Structure Rearrangement Scena-rios: A Heuristic Approach”. It was carried out at NADA and super-vised by associate professor Jens Lagergren.

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39

EconomyTina Billing Ericson

NADA receives its basic financial support from KTH and StockholmUniversity (SU). These funds are used for undergraduate and graduateeducation, and for research. A number of external agencies, notablythe Swedish Agency for Innovation Systems (VINNOVA), the Swe-dish Research Council (VR), European Union (EU), and the Strate-gic Research Foundation (SSF), support various research projects.

All grants up to 96/97 refer to fiscal years starting July 1st.From 1998 the fiscal year starts January 1st. Starting January 97,KTH grants increased by 16.7% to cover office rent. From January1999 the same grants increased by an additional 16% to coveruniversity overhead costs. The economic growth is evident in thefinancial situation illustrated below.

0 20 40 60 80 100 120 140 160 180 200

82/83

84/85

86/87

88/89

90/91

92/93

94/95

96/97

1999

2001

MSEK

Year

Undergraduate Education

Research & Graduate Education

External Funds

Total financing of NADA 1982/83 to 2001.The total turnover of fiscal year 2001 was 202.4 MSEK. The activitiesfinanced externally were as follows

Computer ScienceComputational Vision and Active Perception Laboratory (CVAP) 13.2Interaction and Presentation Laboratory (IPLab) 4.2Centre for user-oriented IT Design (CID) 14.7Studies of Artificial Neural Systems (SANS) 1.5Theoretical Computer Science (TCS) 5.4

Numerical AnalysisNumerical Analysis (NA) 14.2

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Media Technology and Graphic Arts (MEDIA) 4.5

OthersKTH Network Operation Centre (KTHNOC) 11.7Center for Parallel Computers (PDC) 28.6Other Services 3.9

TCS 5.4CVAP 13.2

IPLAB 4.2

CID 14.7

SANS 1.5

NA 14.2

MEDIA 4.5

KTHNOC 11.7

PDC 28.6

Undergraduate Education 61.7

Research and Graduate Education 38.8

Other Services 3.9

Total turnover by activity 2001 in MSEK.

NADA hosts three research centres: CAS, CID, and PSCI. Some ofthe research at these centres is carried out at other departments atKTH, and at other universities. The research at NADA financed bythese centres is included in the turnover above under the activitiesCVAP, CID, and NA. For 2001 the total turnover in MSEK wasCAS (Centre for Autonomous Systems) 11.2CID (Centre for User Orientated IT Design) 14.7PSCI (Parallel and Scientific Computing Institute) 14.9

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History of NADA

42

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History of NADAIngrid Melinder

1962 Department of Numerical Analysis, offshoot of AppliedMathematics.

1963 Sweden’s first professorship in Numerical Analysis:Germund Dahlquist. Personnel: 6 staff members.

1964 Calculator-room with 15 electric desk calculators: FACITCA13.

1965 We merge with Administrative Data Processing and formthe Department of Information Processing.

1967 Temporary computer in the building: CDC3200.1968 Centralization to regional IBM-system. Computer Centre

QZ established.1970 Minicomputer HP2000 with 8 Teletype terminals.1972 Administrative Data Processing moves to Frescati.1974 Mainframe dialogue computer, DEC-10, stationed at QZ.1977 University reform, links with Administrative Data

Processing are dissolved.Two terminal halls with30 terminals in total.

1979 Change of name: Numerical Analysis and Computing Sci-ence, NADA. Nadja: DEC2020 computer for ourcourses.

1980 An electronic terminal exchange is installed.1981 New terminal halls containing 41 terminals.1982 Professor in Computer Science: Stefan Arnborg.

Vera: DEC2060 computer for our research andpostgraduate courses. Four-year Computer Science optionwithin School of Mathematics at Stockholm University.Personnel: around 40 permanent staff members.

1983 School of Computer Science and Engineering (D) at KTH.Terminal halls enlarged to contain 76 terminals.

1984 Advanced graphic workstations: XEROX 1108.First laser printer: Canon LBP-10.Duvan: VAX 11/750 computer for courses within school D.Successive extension of Ethernet computer network at KTH.

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1985 Two workstation labs for D-students, containing in total24 Apple Macintosh personal computers, 2 laser printersand 4 graphic workstations.Computer Vision and Graphics Laboratory established withequipment for research on image analysis and graphics, e.g.Bogart: VAX 11/750 computer.Venus: DEC2020 computer for our basic courses.

1986 Professor in Computer Vision: Jan-Olof Eklundh.Workstations for Smalltalk: Tectronix 4405 and 4406.Large dedicated Unix computer for education at D: Draken(Pyramid 9820).

1987 Personnel: around 75 permanent staff members.Adjoint professor of Information Psychology: HansMarmolin.

1988 Center for Computational Mathematics and Mechanics,C2M2, started inside Nada. Professor Heinz-Otto Kreiss isthe scientific leader.

1990 SUN-servers 4/490 installed, replacing and enhancing DEC2020/2060 and Pyramid computers.

1991 Professor Germund Dahlquist retired. New professor atNada: Björn Engquist.Personnel: around 90 permanent staff members.All text terminals exchanged to XWindow-terminals (92 forstudents).

1992 Professor in Theoretical Computer Science: Johan Håstad.Reorganization at KTH; KTH Network Operation Centre(KTHNOC) transferred to Nada. Laboratory with 8 NeXTcomputers.

1993 Center for Parallel Computers (PDC) associated with Nada.Silicon Graphics Workstations (Onyx and Indigos).

1996 Centre for Autonomous Systems (CAS) hosted by Nada.Adjoint professor in Scientific and Statistic DatabaseTreatment: Per Svensson.PDC computers: Cray J932 and Fujitsu VX and a VirtualReality lab with an ImmersaDesk was opened.

1997 Professor in Human Computer Interaction: KerstinSeverinson-Eklundh.Personnel: around 160 permanent staff members.

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1998 Professor in Computer Science, Autonomous systems:Henrik Christensen.Human-computer interaction become a separate academicdiscipline.PDC six-surface VR-CUBE system (SGI Onyx2 andInfiniteReality graphics pipes).

1999 PDC computer: IBM SP-2 upgraded to 170 separateprocessor nodes.Donation by Sun Microsystems AB: 20 Sun Ultra10 workstations.

The name of the department is changed to Numerical Analysis and Computer Science.

2000 Stockholm Bioinformatics Center, SBC hosted by the department of Bio Chemistry, SU. NADA is one partner.

2000 The research group Media Technology and Graphic Arts moves to NADA. Chair Professor: Nils Enlund.

2001 Chair Professor in Applied Numerical Analysis: Lennart Johnsson. Donation by IBM: A cluster of one Master and 15 IBM Netfinity 4500R Computers to build a Linux lab.

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Ongoing Research inComputer Science

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Jan-Olof Eklundh, Stefan Carlsson, Tony Lindeberg, HenrikChristensen

CVAP performs research in computer vision and robotics. The groupwas formed in 1982 and has today about 30 researchers and researchstudents.

The computer vision research is currently mainly funded throughtwo Swedish sources, TFR, the Swedish Research Council for Engi-neering Science, and SSF, the Swedish Foundation for Strategic Re-search, and through grants from the European Union. CVAP has since1993 a so called frame grant from TFR and is a partner in two consor-tia sponsored by SSF: CAS, The Center for Autonomous Systems,and VISIT, Visual Information Technology. CAS is hosted by NADAand an overall description of the center can be found in this volume.VISIT is a national research program hosted by Uppsala University,and involves groups from seven Swedish universities. CVAP togetherwith Karolinska Institutet participates in the project BINS, Brain ImageNeuroinformatics Systems, supported by SSF, and has a TFR projecton the analysis of functional brain images. Jointly with CID, CVAPhas had a project supported by NUTEK on computer vision for hu-man-computer interaction. The group has during the period of thisreport participated in the EU LTR project IMPROOFS and the EUTMR networks VIRGO and CAMERA, all of which are now fin-ished. In 2000 and 2001 CVAP has become a partner of several newEU-projects. The group coordinates the two projects CogVis, on sys-tems for cognitive vision, and VIBES, on computer vision for brows-ing, indexing and visualization. It is furthermore a partner in Insight2+,in which groups in biological and machine vision study perception ofmaterials and shape, and particpates in the project Neurogenerator ondeveloping a database system for functional mapping of the humanbrain. Finally, CVAP has one Research Fellow supported by the RoyalSwedish Academy of Sciences and one postdoctoral fellow in theMarie Curie program. The robotics research in the group is integratedwithin CAS and described under that heading.

Computational Vision andActive Perception Laboratory, CVAP

CVAP performs research incomputer vision and robot-ics.

www.bion.kth.se

50

We will in the next few sections give an overview of the main topicsof the on-going research at CVAP, in particular reporting the resultsfrom 2000-2001. More references to our work can be found in the listof publications on CVAP's homepage. <www.bion.kth.se>

Seeing systemsLiving creatures use their senses to guide their actions and also, con-versely, act to capture sensory information. This tight connection be-tween perception and action has formed a basis for a large part of theresearch at CVAP for the past ten years. In fact, since the start of theCenter for Autonomous Systems in 1996 the research has been evenmore focused on studying computational vision in the embodimentof seeing robots and in conjunction with behaviors of mobility andmanipulation.

In a general sense our long term research deals with the princi-ples of a seeing agent. One assumption in this work has been that theagent is capable of binocular fixation of moving objects in a dynamicfashion, i.e. when both the objects and the observer are moving. Suchcapabilities were demonstrated already by [Pahlavan et al., 1996],but computational limitations then restricted the use of them in higherlevel visual tasks. Therefore, we have continued this work to showthat disparities, depth, and ego-motion can be computed in real-timeat fixation. A key point here is that estimation of the epipolar geom-etry is simple in such a case (two free parameters). An importantconsequence of this approach is thatit allows segmentation of threedimensional objects from their background for subsequent process-ing, and e.g. computation of layered representation of the scene. Sincethree-dimensional cues indeed indicate physically distinct chunks ofthe scene this provides potential clues for attention and recognition,see [Maki et al., 2000].

The integration of multiple cues is an important feature of thedescribed approaches and a central theme of our efforts in general. In[Kragic and Christensen, 2000a, b, c,][ Christensen and Eklundh,2000][Kragic and Christensen, 2001] and [Kragic, 2001], such inte-gration is performed for visual tracking and servoing using votingmethods. These methods are shown to give robustness even when theindividual cues are highly uncertain, provided that enough cues areavailable, in the experiments 3-5. Ongoing work aims at furtheranalyzing these findings on statistical grounds. In addition, the meth-

<www.bion.kth.se>

In a general sense our longterm research deals with theprinciples of a seeing agent.

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ods are applied for vision based manipulation of objects using bothstatic and mobile manipulators, see the section on CAS.

The described work provides a basis for our longterm researchon the design and development of vision systems for seeing agents.These systems should have cognitive abilities, i.e. be able to know,understand, and learn things. In the recently started EU-project CogViswe are therefore addressing problems on recognition and categoriza-tion of objects, events, and activities, and how such abilities can beused by a mobile observer performing tasks such as navigation, fetch-and carry, and manipulation. Important issues concern how task in-formation and context can be used to limit the computational com-plexity and to obtain robust performance. Representational issues andlearning are of course also central. Here, we have up to now studiedview based approaches to object recognition, in particular using Sup-port Vector Machine learning, see [Roobaert, 2000][Roobaert et al.,2001]and [Roobaert, 2001]. One contribution introduces a simpli-fied, approximate SVM technique, that gives faster learning than theoriginal method, with small errors on the classification. Another con-tribution is a study of how objects can be recognized against varyingbackgrounds by well-chosen examples during learning, a techniquecalled pedagogical learning.

An assumption underlying our research on categorization andrecognition of everyday objects is that these processes should be con-sidered relative to the tasks of the seeing system and be based on thecontext in which it finds itself. The internal representations obtainedby SVM and other pattern recognition methods are not suitable forexplicit and predicitive use of context and knowledge. Therefore,current work focuses on the use of multiple representations as well asmultiple cues for recognition and categorization. Also in this casevoting methods and probabilistic techniques form central themes. Theclose interplay between figure-ground segmentation, attention, andrecognition as another important aspect studied. So far we have mainlyconsidered bottom-up attention, but top-down influences will soonbe studied as well. A particular problem then concerns the conflictingrequirements of these two. Preliminary work on how that can be han-dled is going on.

A particular problem in scene interpretation is the analysis andunderstanding of human motion and activity. We are in collaborationwith M. Black, Brown University, studying this problem, with an

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emphasis on three-dimensional models and using probabilistic tech-niques, see [Sidenbladh et al, 2000][Ormoneit et al., 2000][Sidenbladh and Black, 2001] and [Sidenbladh, 2001]. In other workwe address similar problems in a multisensor framework for robotapplications, [Lindström & Eklundh, 2001]. More specifically,“where”, the location of the target is then derived from sensors giv-ing range, while “what”, the identity or activitity of the target is com-puted using vision. The particular application studied is the analysisand classification of human activity. More general problems on struc-ture from motion and the reconstruction of three dimensional sceneshave also been considered, see [Nister, 2001][Zuccchelli andChristensen, 2001][Zuccchelli and Kosecka, 2001] and [Zuccchelliand Cervone, 2001].

Robust vision systems functioning in real-world situations canonly be realized if photometric and illumination effects are taken intoaccount. This is the topic of the new EU-project Insight2+, in whichthe role of material properties and illumination in shape understand-ing and object recognition in man and machine are investigated.[Nillius and Eklundh, 2001] present a method for estimating the pro-jected direction to the light source from a single image. Current workapplies statistical methods and learning to the estimation of materialproperties from images of surfaces.

Scale-space theory with applicationsThe algorithmic design of a computer vision system depends on whatkind of system we are aiming at. If the aim is to solve only a specificmachine vision problem, we could in principle use any set of algo-rithms that performs the given task. If we on the other hand are inter-ested in constructing flexible vision systems with the ability to solvea large number of visual tasks, then it is natural to aim at a certaingenerality in design, such that processing modules can be shared be-tween several algorithms or processes for solving different visual tasks.If such modules are to be constructed without built-in limitations thatwould restrict their applicability, then a natural requirement is thatthe first stages of processing should be as generic and uncommittedas possible [Lindeberg, 1994]. This problem can be given a rathergeneral formulation concerning the image operations at the lowestprocessing levels, and has led to the development of scale-space theory.The CVAP group has both contributed to the foundations of scale-

The particular applicationstudied is the analysis andclassification of human activ-ity.

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space theory and applied it to different computer vision problems.Scale-space theory, as proposed by Iijima, Witkin, and

Koenderink, states that any given image should be represented atmultiple scales by smoothing it by convolution with Gaussian ker-nels of increasing width. A main motivation for this operation is tomake the multi-scale nature of data more explicit by gradually sup-pressing fine-scale information. Specifically, the output from suchfilters can be used as a basis for expressing large classes of visualoperations, including feature detection, shape description, stereomatching, motion estimation, tracking and recognition. In a scale-space representation by itself, however, there is no explicit informa-tion about what scales are appropriate for describing a given data set.To address this issue, we have in earlier work developed a generalframework for automatic scale selection by local maximization ofnormalized differential invariants over scales [Lindeberg, 1998a, b]or by local minimization of error measures over scales [Lindeberg,1998c]. Examples of recent works where these general scale selec-tion principles have then been applied include fingerprint analysis[Almansa and Lindeberg, 2000] and steel quality inspection [Wiltschiet al., 2000].

Another area where the scale selection approach has been ex-tensively applied is with regard to the problem of tracking and recog-nizing hand gestures based on local multi-scale image features[Bretzner and Lindeberg, 2000][ Laptev and Lindeberg, 2001a]. Basedon a scale invariant similarity measure for image features in combi-nation with complementary colour cues, we have developed an ap-proach for evaluating the likelihood of hierarchical parameterizedmodels in such a way that simultaneous model selection and param-eter estimation can be performed at multiple scales. Then, by integra-tion with the notion of particle filtering a feature-based method forsimultaneous tracking and recognition of hand models has been pre-sented. These algorithms have been integrated into a real-time sys-tem for hand gesture analysis, and have been evaluated with regardto the problem controlling computerized equipment using hand ges-tures [Bretzner et al., 2001]; an area that is studied in collaborationwith the Cid Centre for User Oriented IT Design at KTH. With re-gard to the topic of simultaneous tracking and recognition, we havealso investigated a complementary approach of evaluating objecthypotheses in particle filtering schemes directly from local filter out-

...the problem of tracking andrecognizing hand gestures...

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puts, based on the notion of filter likelihood maps [Laptev andLindeberg, 2001b]. An important component to obtain real-time per-formance of the automatic scale selection step in this context is toperform the implementation in terms of a pyramid representation,referred to as hybrid multi-scale representation [Lindeberg andNiemenmaa, 2001]. On-going work aims at exploring spatio-tempo-ral scale-space involving velocity adaptation [Lindeberg, 2001] andrecognition of space-time events [Laptev and Lindeberg, 2001c].

In collaboration with the Division of Human Brain Research atthe Karolinska Institute, we are working on several topics in medicalimage analysis. Within the BINS and NeuroGenerator projects, weare developing fully automated processing chains for analysing func-tional PET and fMRI brain activation experiments, and contribute tothe design of integrated database environment for analysing large setsof functional brain experiments [Roland et al., 2001]. Examples ofimage processing algorithms developed under this collaboration in-clude multi-scale detection of regions of functional activation[Rosbacke et al., 2001][Zagal et al., 2000] and fully automatic brainsegmentation algorithms based on probabilistic diffusion in combi-nation with prior information in terms of a pre-segmented brain atlas[Undeman and Lindeberg, 2001],

Geometric and statistical computingThe image projected from a 3D scene will vary with the viewpoint ofthe observer. This variation is a source of information for severalapplications of computer vision such as visual servoing for robotics,recognition of 3D objects and 3D reconstruction from multiple views.A central problem for all of these applications is the establishment ofcorrespondence between images from different viewpoints. If theviewpoints are far apart as many interesting applications require, thecorrespondence problem is hard due to the difficulty of computinginvariants to be used for the establishment of correspondence. Forpiecewise planar or nearly planar surfaces we have exploited the factthat points in different views are in projective or affine correspond-ence depending on the camera model. This means that any points ona line connecting two points are also in correspondence. Intensityprofiles along these lines are therefore ideal matching features andcan be used to establish corespondence of the end points [Tell andCarlsson, 2000]. This algorithm has been implemented in a camera-

...we are working on severaltopics in medical imageanalysis.

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robot arm visual servoing system and shown to work reliably for prac-tical grasping problems [Tell, 2001].

A major goal for any 3D object recognition system is toachieveviewpoint invariance or at least robustness towards variationof viewpoints. For general point sets in 3D it can be shown that it isnot possible to compute any viewpoint invariants from a single im-age. Given two views of pointsets in 3D however, it is possible todecide whether they are projected from the same 3D set. This can bedone by evaluating a view-consistency polynomial in the projectedimage coordinates. This provides us with a tool for matching viewsof point sets in order to decide if they have the same 3D structure.These view consistency polynomials have been derived for the caseof scaled orthographic cameras and the matching procedure has beenapplied to the problem of recognizing walking people using interac-tively extracted image points of specific body locations [Carlsson,2000]. By using stored sequences of 8 walking people acquired froma specific viewpoint, identification of a certain person from a sequencetaken from a different viewpoint is around 95 % with a few percentpossibility of false positives.

The multiple images obtained by varying the viewpoint of acamera are a source of information about the 3D scene or object be-ing imaged. If the images are acquired from known camera positions,the 3D reconstruction problem becomes fairly straightforward oncecorresponding points in multiple views have been found. The moregeneral situation where the camera positions are not known a priori isfar more complex however. In this case the camera positions andorientations have to be computed from the projected image data alone.If the metric structure of the 3D scene is known, this is a standardcalibration problem. Even if only qualitative information about the3D scene is known, calibration and thereby complete metric 3D re-construction can be computed. This is the case of two cameras view-ing a person over extended time. The fact that the length of bodyparts such as upper arms e.g remains constant over time can be usedas a calibration constraint. This has been exploited in [Liebowitz andCarlsson, 2001] in order to compute 3D animation of sports eventsfrom cameras with completely unknown parameters which implies avery effective extension of the technique of motion capture to in-clude un calibrated camera systems.

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Given multiple views of a scene the general problem of simultaneouscalibration and reconstruction is bilinear. For parallel projection cam-eras there is an efficient factorization algorithm for this problem givenimages of sets of points in 3D. This algorithm assumes that all pointsare visible in all views which is a drawback. For perspective projec-tion cameras, no such simple factorization is in general possible.However, by assuming that a planar surface or just four coplanar pointsare visible in all views, there is a direct single step linear algorithmfor simultaneous camera calibration and reconstruction based on find-ing the null-space of a matrix constructed from image coordinates ofpoints in multiple views [Rother and Carlsson, 2001a]. This algo-rithm does not require all points to be visible in all views, just thecoplanar reference points. This makes it a very interesting practicalalternative to existing algorithms for multiple view calibration andreconstruction that cannot handle all views in a single step. This al-gorithm is being extended to handle the general case with no coplanarreference points available [Rother and Carlsson, 2001b]. There is aninteresting special case of this algorithm where the reference pointsare choosen at the plane at infinity, visible in the image through thevanishing points that can be computed in typical architectural scenes.[Rother, 2000].

The problem of recognizing general categories of objects is oftena problem of general shape recognition. The algorithm for generalshape matching based on topological type equivalence that was pre-sented in [Carlsson, 1999] has been extended and improved from acomputational point of view. The purpose is to be able to recognizeobject categories in real images with background and occlusion[Thuresson and Carlsson, 2001] [Thuresson and Carlsson, 2001]. Thealgorithm has also been applied to the problem of recognizing humanaction from specific poses. As an example, in a 30 sec sequence oftennis containing 12 forehand shots we are able to find all specificframes depicting the initiation of the forehand shot with no false posi-tives. [Carlsson and Sullivan, 2001]. This work will be extended torecognition based on multiple frames for characterizing an action.The recognition of specific frames in an action sequence is also beingused to track specific body locations in order to automate 3D recon-struction of human motion based on the ideas described previouslySullivan et al., 2001].

The problem of recognizinggeneral categories of objectsis often a problem of generalshape recognition

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[Carlsson, 1999] Carlsson, S., Order Structure, Correspondence andShape Based categories International Workshop on Shape, Con-tour and Grouping, Springer Lecture Notes in Computer Science1681, 1999.

[Carlsson, 2000] Carlsson, S., Recognizing Walking People, Proc 6:th ECCV, Dublin, Ireland, Springer LNCS 1842-1843 june 2000

[Carlsson and Sullivan, 2001] Carlsson, S. and Sullivan, J. ActionRecognition by Shape Matching to Key Frames Workshop onModel versus Exemplars in Computer Vision, Kauai, Hawaii, USADecember 14th, 2001

[Christensen and Eklundh, 2000] Christensen, H. I., and Eklundh,J.-O., Active vision from multiple cues, in Biologically MotivatedComputer Vision (S.-W. Lee, H. Bulthoff, and T. Poggio, eds.),(Seoul, Korea), pp. 209-216, Springer Verlag, May 2000. LNCS-1811.

[Kragic and Christensen, 2000a] Kragic, D., and Christensen, H. I,.A framework for visual servoing tasks, in Proc. Intelligent Au-tonomous Systems 6, IAS-6 (E. Pagello et al., ed.), (Venice, Italy),pp. 835-842, July 2000.

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[Kragic and Christensen, 2000b] Kragic, D., and Christensen, H.I.,Tracking techniques for visual servoing tasks, in Proc. IEEE In-ternational Conference on Robotics and Automation, vol. 2, (SanFrancisco, CA, USA), pp. 1663-1669, May 2000.

[Kragic and Christensen, 2000c] Kragic, D., and Christensen, H. I.,Cue integration for manipulation, in Robust vision for vision-basedcontrol of motion (M. Vincze and G.D. Hager, eds.), pp. 1-16,IEEE Press ISBN 0780353781, 2000.

[Kragic, 2001] Kragic, D., Visual Servoing for Manipulation: Ro-bustness and Integration Issues, Doctoral Dissertation, ISRN KTH/NA/P-01/16-SE, June 2001.

[Kragic and Christensen, 2001] Kragic, D., and Christensen, H. I.,Cue integration for visual servoing, IEEE Transactions on Robot-ics and Automation, vol. 17, no. 1, pp. 18-27, 2001.

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[Laptev and Lindeberg, 2001b] Laptev, I., and Lindeberg, T., A multi-scale feature likelihood map for direct evaluation of object hypoth-eses, in Proc. Scale-Space'01, (Vancouver, Canada), SpringerVerlag Lecture Notes in Computer Science, vol 2106, pp 98-110,July 2001.

[Laptev and Lindeberg, 2001c] Laptev, I., and Lindeberg, T., in preparation.

[Liebowitz and Carlsson, 2001] Liebowitz, D., and Carlsson, S.,Un-calibrated Motion Capture Exploiting Articulated StructureConstraints, Proc 8:th ICCV, Vancouver, Canada, July 2001.

[Lindeberg, 1994] Lindeberg, T. Scale-Space Theory in Computer Vision, Kluwer 1994.

[Lindeberg, 1998a] Lindeberg, T., Feature detection with automatic scale selection, International Journal of Computer Vision, vol.30, no. 2, pp. 77-116, 1998.

[Lindeberg, 1998b] Lindeberg, T., Edge detection and ridge detec-tion with automatic scale selection, International Journal of Com-puter Vision, vol. 30, no. 2, pp. 117-154, 1998

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[Lindeberg, 1998c] Lindeberg, T., A scale selection principle forestimating image deformations, Image and Vision Computing,vol.16, no. 14, pp. 961-977, 1998.

[Lindeberg, 2001] Lindeberg, T., Linear spatio-temporal scale-space, in preparation.

[Lindeberg and Niemenmaa, 2001] Lindeberg, T., and Niemenmaa,J., in preparation.

[Lindstrom and Eklundh, 2001] Lindström, M., and Eklundh, J.-O.,Detecting and tracking moving objects from a mobile platformusing a laser range scanner, in Proc. IEEE International Confer-ence on Intelligent Robots and Systems IROS'2001, (Maui, Ha-waii), October 2001. (in press).

[Maki et al., 2000] Maki, A., Nordlund, P., and Eklundh, J.-O.,Attentional scene segmentation integrating depth and motion, Com-puter Vision and Image Understanding, vol. 78, pp. 351-373, June2000.

[Nillius and Eklundh, 2001] Nillius, P., and Eklundh, J.-O., Auto-matic estimation of the projected light source direction, in Proc.IEEE Computer Vision and Pattern Recognition, CVPR'01, (Kauai,Hawaii), December 2001. (in press).

[Nister, 2001] D. Nistér, Automatic dense reconstruction from uncalibrated video sequences, Doctoral Dissertation, ISRN KTH/NA/P-01/02-SE, 2001.

[Ormoneit et al., 2000] Ormoneit, D., Sidenbladh, H., Black, M. J.,and Hastie, T., Learning and tracking cyclic human motion, inEEE Workshop on Human Modeling, Analysis and Synthesis,(Hilton Head SC USA), June 2000.

[Pahlavan et al., 1996] Pahlavan, K., Uhlin, T., and Eklundh, J.-O., Dynamic fixation and active perception, International Journal ofComputer Vision, vol. 17, pp. 113-135, 1996.

[Roland et al., 2001] Roland, P., Svensson, G., L indeberg, T., Risch,T., Baumann, P., Dehmel, A., Fredriksson, J., Halldorsson, H.,Forsberg, L., Young, J., and Zilles, K., A database generator forhuman brain imaging, Trends in Neuroscience, vol. 24, pp. 562-564, October 2001.

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[Roobaert, 2001] Roobaert, D., Pedagogical Support Vector Learn-ing: A Pure Learning Approach to Object Recognition, DoctoralDissertation, ISRN KTH/NA/P-01/15-SE, May 2001.

[Roobaert et al., 2001] Roobaert, D., Zillich, M., and Eklundh,J.-O., A pure learning approach to background-invariant object recogni-tion using pedagocical support vector learning, in Proc. IEEE Com-puter Vision and Pattern Recognition, CVPR'01, (Kauai, Hawaii),December 2001. (in press).

[Rosbacke et al., 2001] Rosbacke, M., Roland, P. E., and Lindeberg,T., Evaluation of using absolute vs. relative base level when ana-lyzing brain activation images using the scale-space primal sketch,Journal of Medical Image Analysis, vol. 5, Issue 2, pp. 89-110,2001.

[Rother, 2000] Rother, C., A New Approach for Vanishing Point De-tection in Architectural Environments, BMVC 2000, Bristol, GB,11- 14 september, 2000.

[Rother and Carlsson, 2001a] Rother, C., and Carlsson, S., Linear Multi View Reconstruction and Camera Recovery, Proc 8:th ICCV,Vancouver, Canada, July 2001.

[Rother and Carlsson, 2001b] Rother, C., and Carlsson, S., inpreparation.

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[Tell and Carlsson, 2001] Tell, D., and Carlsson, S., Wide Baseline Point Matching Using Affine Invariants Computed from IntensityProfiles Proc 6:th ECCV , Dublin, Ireland, Springer LNCS pp.1842-1843 june 2000.

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Anders Lansner

The SANS research group was formed in 1987. At the end of 2001 itconsisted of four lecturers, three research assistants, and eight PhDstudents. Our research focuses on theoretical and computational neuro-science, that is, mathematical modeling and computer simulation ofbiological nervous systems, the brain in particular. Our primary aimis to improve our understanding of the principles underlying theirinformation processing capabilities. Our models extend from thoseincorporating biological details of cellular processes, neurons, andneuronal networks to abstract connectionist type models and artificialneural networks and systems.

Being a computer science group, SANS also emphasizes theengineering and applications aspects of understanding biological in-formation processing, namely the use of this knowledge in the designof advanced technical systems. The human brain still outperformstoday’s supercomputers by several orders of magnitude in terms ofprocessing and memory capacity as well as in compactness,robustness, and low power dissipation. No technical design comesanywhere close to its performance in tasks like vision, speech andlanguage understanding, or motor control. We regard it as our majorresearch challenge to find out how such performance is possible, tocontribute in uncovering the underlying information-processingprinciples, and to investigate how the knowledge gained can be utilizedin the design of future man-made autonomous learning systems.

It is quite likely that progress along these lines will be rapid inthe next couple of decades. Increasingly advanced experimentaltechniques together with mathematical modeling and computer si-mulation are enabling methodologies for achieving this. Furthermore,provided that the historical trends in hardware development continue,man-made computing technology will approach the estimated capa-city of the human brain within the next few decades. If so, the technicalpotential of brain-like computing will begin to materialize in the firstdecades of the third millennium.

The SANS group benefits from a long-standing and closecollaboration with neurophysiologists at the Department of Neuro-science, Karolinska Institutet (Professor Grillner and co-workers). In

Studies of Artificial Neural Systems, SANS

www.nada.kth.se/sans

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recent years, collaboration has been further extended to other experi-mental groups in neuroscience, neuropsychology, and molecular medi-cine. SANS is also engaged in technical applications of artificiallearning systems in collaboration with SICS (the ARC group, G. Sjö-din). The main sources of external funding are presently VR, EC, andVinnova.

SANS Research ThemesThe major components of the brain are the sensory-perceptual-memorysystems, the behavioral-motor systems, and the sub-cortical moti-vational and emotional systems. Throughout, plasticity, self-organization, and learning are fundamental properties. Over the years,the SANS group has investigated several of these fundamentalcomponents and their functions, including associative memory, ge-neration and control of locomotion, behavior selection, andreinforcement learning.

In our study of adaptivity and plasticity, we focus on biologicallyplausible forms like self-organization of structure and unsupervisedand trial-and-error kinds of learning. Further, when investigating braininformation processing we emphasize the network level of informa-tion processing rather than sub-cellular level computation.Nevertheless, for a more detailed understanding of many biologicalprocesses and systems this level is crucial. Here, models are able tobuild on new developments in molecular biology and are likely toform an important integrative/synthetic role in future biomedicine,drug design, etc. We have therefore recently expanded our modelingactivities in this direction. Below follow descriptions of the differentprojects conducted over the last two years.

Perception and MemoryPerception and memory processes are closely intertwined in theparallel and distributed processing networks of the brain. For a longtime, our research in this direction has focused on attractor networkmodels. As with motor systems modeling, we have found it highlyuseful to investigate the same or similar systems using a spectrum ofmodels from biophysically detailed ones to reduced and abstractmodels.

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Dynamics of Learning and Recall in Attractor Neural NetworksAnders Lansner, Anders Sandberg, Christopher Johansson

The goal of this project is to link abstract attractor neural networkmodels to psychological and neural data. It takes a systems perspectiveon memory, studying what features and building blocks are needed toproduce autonomous adaptive functions. So far the main results havebeen in the form of minimal models able to reproduce memory effectssuch as the Sternberg working memory reaction time task, the vonRestorff effect in list learning, and spontaneous reinstatement of lear-ned activity patterns.

The main work has been done using extended versions of theBayesian confidence propagation neural network (BCPNN)[Sandberget al., 2000], which now includes Hebbian-Bayesian learning and aphenomenological model of synaptic depression and neural adapta-tion. [Sandberg and Lansner][Wahlgren and Lansner, 2001].

By modulating the learning rate, in analogy with current theories ofneuromodulator effects on synaptic plasticity, the network exhibitsrecall enhancement and inhibition effects similar to the von Restorffeffect in list learning. In order to develop a suitable building blockfor a memory reinstatement model, synaptic depression and neural

Figure 1:Learning and recallof memories in a workingmemory network model.Four memories (activitybumps) are stored. Encodingtakes place in the first 1.5seconds where after thenetwork performs free recall.

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adaptation was added. This enables a meta-stable dynamics wherethe network remains for some 200-300 ms in one attractor state beforeit jumps to the next. Currently work is under way on multi-networkinteractions and models of age-dependent memory decline.

Single neural networks have been studied extensively and theycan be used to solve application problems [Orre et al., 2000]. Recently,systems of several BCPNN were studied in the context of interplayof short- and long-term memory [Johansson, 2001][Johansson et al.,2001].

The last couple of years have seen the development of a BCPNNwith hypercolumns. A simulator of the most recent version of theBCPNN has now been developed. It has populations and projectionsas the basic building blocks and provides an easy way to constructcomplex multi-network architectures. The simulator is developed inC, and it is accompanied by a Java interface.

The hypercolumn structured BCPNN is further well suited forparallel implementation, and it has been implemented with two parallelAPI:s (MPI, OpenMP) and on a number of different computer systems− 100 processors on an IBM SP2, a 12-processor SGI Onyx 2, and aLAN of 10 SunBlade 100 workstations. The parallel implementationof the BCPNN has allowed capacity studies of large-scale networks[Johansson and Lansner 2001].

Working Memory in the Entorhinal CortexErik Fransén

In this project biophysical modeling of nerve cells is done to studythe function of a brain region named entorhinal cortex (EC). At pre-sent the project studies the working memory function of the EC bylooking both at nerve cell properties and at how the cells operatewhen they are connected to each other in a network [Hasselmo et al.,2000][Fransén et al., 2001a].

Cells are described by their electrical properties as well as someof the biochemical processes involving calcium. Mathematical formu-las describing this flow of ions in and out of the cell are solvednumerically using a special-purpose simulator for nerve cells. Due tothe relatively detailed modeling of the cells, experimental data is easilyincluded. The evaluation of the model, by comparing generated resultsto experimental data, is likewise efficient and instructive.

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The EC is very interesting as it is positioned as a gateway betweenthe neocortex, which is the region of the brain responsible for highercognitive functions; and the hippocampal system, which is one of thekey components of the brain's memory system. The EC is alsoimportant from a clinical perspective. One of the major forms ofepilepsy involves the EC. Further, in Alzheimer's disease, the firstregion to show signs of change is the EC.

stim A

stim B

pyrA

stel

pyrAB

intpost cell

pre cell

high I(NCM) current

low I(NCM) current

no I(NCM) current

stimulation

I(NCM) saturation

inhibitory feedback500 ms

100

mV

A

B

C

D

E

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Figure 2: A network modelwith cells and their synapticconnections. Triangles rep-resent pyramidal cells, thesquare a stellate cell and thecircle an inhibitory interneu-ron.

Figure 3: Results from simu-lations of a single pyramidalcell with external input (sti-mulation). The differenttraces show the effect of theion current I

NCM for various

cases.

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The results so far include simulations of working memory functionin a so-called delay match-to-sample experiment [Fransén et al.,2001a]. This was achieved by first constructing models of stellate,pyramidal, and inhibitory cells. For the stellate cell an ion-channel,named the H-channel, has been studied thoroughly [Dickson et al.,2000]. For the pyramidal cell the properties of a cationic channelnamed NCM have been studied [Fransén et al., 2000][Fransén et al.,2001c]. This channel is activated by the neuromodulator acetylcholine,a substance that has been shown to be of great importance for workingmemory function in this region of the brain.

Visualization of Neural Network Activity and LearningAlex Kozlov, Marcus Weiland, Anders Sandberg

The behavior of neural networks is highly dynamic and complex,often involving a large number of state variables and interconnections.Hence tools for visualizing neural network information are needed.Some preliminary work on visualization of neural network activityand learning dynamics has been done.

Marcus Weiland developed oglFromFile, an application in-tended as a link to neural network simulations to create animations orinteractive graphics. This was subsequently ported by Anders Sand-berg to the KTH VR-Cube. Applications include visualization of theweight dynamics of attractor neural networks using graph layoutalgorithms, and display of large-scale simulations of the lamprey spi-nal network.

Motor Control and Behavior SelectionWe have been successfully developing models of vertebrate loco-motion for a long time. This work is still highly active and has entereda new and productive phase with an even more close interaction withexperimentalists. A highly important issue in motor control is howthe basic motor programs are combined into more complex behaviorsand how these are selected given a certain situation and goal. Morerecently we have initiated studies of these integrative functions aswell. The analogy between algorithms and theories of reinforcementlearning on one hand, and animal learning dynamics and cellularlearning processes observed in the basal ganglia on the other, servesas important sources of inspiration in this research.

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Neuro-Dynamics of the Central PatternGenerator for Swimming in LampreyAlex Kozlov, Jeanette Hellgren Kotaleski, Anders Lansner

The central pattern generator (CPG) responsible for the swimmingrhythm generation in lamprey is studied. It comprises a large numberof neurons distributed along the spinal cord of the animal. Theswimming pattern it generates is a wave of intermittent left-right ex-citation running along the spinal cord from head to tail causing themuscles to contract and thus push the body through the water. Thedynamics of this CPG is studied through modeling based onneurophysiological experimental data. Models of different levels ofabstraction are used − from relatively simple chains of nonlinearoscillators to biophysically detailed large-scale neural networks.Modeling allows us to study integral network effects of physiologicalphenomena observed on cellular and sub-cellular levels.

In a recent study, synaptic plasticity in the lamprey spinal CPG inducedby two different substances (5-HT and substance P) was shown toaffect the dynamic burst frequency range of the swimming rhythmgenerator [Kozlov et al., 2001a].

Figure 4: A frame from amovie sequence visualizingthe activity in a full-scalemodel of the spinal swimm-ing rhythm generating cir-cuitry of the lamprey. Thereare ten thousand neuronsshown as spheres withactivity colour coded (blue =low, red = high).

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Another study has shown that postural correction commands fromreticulospinal centers provide information sufficient to stabilize bodyorientation in the roll plane in the lamprey [Kozlov et al., 2001b].Modeling of turn responses to noxious skin stimuli during fictivelocomotion revealed the importance of slow dynamics of intracellularcalcium for shaping realistic patterns of neural activity [Kozlov etal., 2001c][Kozlov et al., 2001d].

The simulation software used was optimized for simulation oflarge networks [Hammarlund and Ekeberg, 1998] and allows bothsegmental and parallel computing. Simulation of space-distributedsystems with complex dynamics requires adequate three-dimensionalpresentation of the data. Special graphics software, OpenGL and POV-Ray, is used for displaying data on conventional monitors and in theVR-Cube.

Modeling Development andLearning of the Human Precision GripAnders Fagergren, Örjan Ekeberg

Current technology in upper limb prostheses is much the same as tenyears ago. This is primarily due to the limited financial resources fordevelopment in the area, since the commercial market for suchproducts is small.

The aim of this research project is to build a mathematical si-mulation model of the human precision grip as a step towards futureprostheses, which communicate directly with the central nervous sys-tem. In the precision grip a small object is grasped between the tipsof the thumb and the index finger. It is a sophisticated function inprimates and humans, used for manipulating small objects. In hum-ans, the precision grip is not fully developed until 8-9 years of age.This project spans over mainly three different research fields, namely(1) prosthetics, (2) the neurobiology of the human grip function, and(3) artificial neural networks. The reason to model any biologicalphenomenon is to increase the knowledge about the biological sys-tem. Furthermore, a powerful feature of a simulation model is thepossibility of making tests, which can be difficult or impossible toperform in reality, for example, destructive tests. Hence, we cansimulate CNS pathology such as CP.

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The model in this research project will include learning as well ascontrol of the precision grip. In order to make as comprehensive amodel as possible, knowledge is needed not only from biology andneuroscience but also from other research fields. To implementlearning in the mathematical simulation model developed in this re-search project we plan to use ANN:s (artificial neural networks).

The first part of the project is now completed and resulted in animplementation of a neuro-biomechanical model equipped with asimple control system required for the precision grip [Fagergren etal., 2000][Fagergren et al., 2001b]. The second part, which most likelywill be the biggest part, will involve the learning and adaptation ofthe precision grip. This will be integrated into the control system.The last part of the project will be to map the model onto the humanneural anatomy. Here, of course, knowledge of the functional structureof CNS will be of greatest interest.

Dynamic Modularization of Neural NetworksPeter Raicevic, Örjan Ekeberg

The brain has a modular structure on many levels, from hemispheresand areas down to the level of minicolumns. When building artificialneural networks (ANN) this feature is often left out, or is designed bythe programmer. This research focuses on finding methods forautomatic modularization of networks during learning.

Figure 5: A frame from amovie sequence of a neuro-mechanical simulation modelof a stick insect. The walkingactivity is driven and con-trolled by a simulated neuro-nal network

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The research is conducted with a feed-forward network on areinforcement problem. An agent moving around, always in the sameenvironment but in different contexts, needs to learn a specific valuefunction for the environment depending on the context. In most placesof the environment the value functions are the same and the represen-tation should be generalized over contexts. In other places where thevalue functions are different the representation should be split. Weare developing an algorithm that starts with a common representa-tion for all contexts and during learning accumulates error in valueprediction and through this decides when to split a representation.This can lead to faster learning and smaller networks and also givesthe networks an ability to adjust to changing environments.

Modeling Learning in the Basal GangliaMikael Djurfeldt, Örjan Ekeberg

During recent years, it has become apparent that the basal ganglia ofthe brain contains key elements of a learning system capable of ma-king decisions about which actions to take based on receivedreinforcement.

In this project, our goal is to study the mechanisms of motorand behavioral learning and decision making in the basal ganglia.The project is a collaboration with professor Ann Graybiel at the Dept.of Brain and Cognitive Sciences, MIT, Cambridge, U.S.A.

In the brain, the dopamine signal from the SNpc (substantianigra pars compacta) has a behavior, which is remarkably similar tothe temporal difference signal in one class of reinforcement learningagents [Schultz et al., 1997]. Because of this, and because ofarchitectural similarities, it has been proposed [Houk et al., 1995]that the components of the basal ganglia can be identified with thecomponents of the actor-critic version of a reinforcement learningagent. This architecture consists of one network computing the valueof actions and one network computing which actions to select in acertain context. The value network has been proposed to involve limbiccortex and the striosomes of the striatum, while the action networkhas been identified with the matrix compartment of the striatum.

We propose that the action network mentioned in the previoussection consists of cortico – basal ganglia – thalamic loops, and thatthe function of the output components of the basal ganglia is to

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modulate attractor states in cortico – thalamic networks [Djurfeldt etal., 2000]. Automated motor and cognitive “programs” can berepresented in the cortico-striatal projection as sets of associationsfrom cortical states to selected attractors.

We have developed a systems-level model with abstract unitswhere the main state variable represents firing rate. The model includesa representation of the projection neurons of the striatum, of the cortico– striatal synapse, of the value network and the attractor states of thecortico – thalamic network. In this type of model we can make aqualitative comparison between predicted and actual changes in firingrate of units during the course of learning. We study the requirementsof the learning rule, identify system components, and get a generalgrasp of what phenomena to expect in each part of the circuit. Weexpect that feedback from experiments will support or falsify ourassumptions, and will give new clues about what to introduce in thenext cycle of model development. New analysis of data acquired withtetrodes in Dr. Graybiel's laboratory gives important clues for howthis learning rule may interact with the architecture of the cortico –basal ganglia network in order to achieve learning of a new habitualbehavior.

A BCPNN-Based Architecture for Reinforcement LearningChristopher Johansson, Anders Lansner

Reinforcement Learning (RL) is a general, simple, and biologicallyplausible scheme for learning. Animals and humans gain newbehavioral programs every day through reinforcement learning.Reinforcement learning is used frequently in computer science invarious ways, but it has not been implemented in a system exclusivelybuilt of neurons. Our aim here has been to investigate whether or notthe basic components of BCPNN are sufficient to implement theappropriate RL functionality.

A system based on BCPNN that implements reinforcementlearning is being developed. Early on it was clear that it was indeedpossible to build an all-neural RL multi-network architecture in thisway. So far, the system has been evaluated in grid-worlds andbenchmarked against common RL algorithms. Preliminary resultsdemonstrate a performance on par with other RL algorithms andfurther investigations are under way.

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Models of Intracellular Processesand Biochemical NetworksThe techniques for modeling intracellular processes are often quitethe same as those used in, for example, compartmental modeling ofneurons. Moreover, there exist important classes of excitable cells(other than neurons), such as pancreatic beta-cells, where thebiochemical and excitable membrane processes are tightly interacting.Additionally, in such tissue, cellular interactions via gap junctionsmay be important determinants of systems dynamic (insulin releasein pancreas). In 1999 a literature survey of cellular level models wasmade [Hellgren Kotaleski and Lansner, 1999]. This study, togetherwith an experimental data analysis collaboration [Björklund et al.,2000], was the starting point for our expanding activities in this field.

The Rhythms of Pancreatic Beta-CellsPål Westermark, Anders Lansner

The physiological function of the pancreatic beta-cells is to secreteinsulin into the blood circulation in response to raised levels of bloodglucose. A better theoretical understanding of this control system isdesirable, since it could spur the discovery of novel therapies againstmetabolic diseases like diabetes and obesity. The intricate complexityof the stimulus-secretion coupling control system in the beta-cells,and the resulting insufficiency of a traditional qualitative biologicaldescription, are the primary motivation for this SANS/PSCIbiocomputing project on pancreatic beta cells.

There is an increasing awareness of the fact that many physio-logical processes are rhythmic. One example is the insulin secretion,which occurs in a pulsatile fashion with a frequency of about 0.2-0.5/min. Also the cellular calcium levels (which are linked to secretion)have been found to oscillate in two distinctly different frequencyranges of about 0.3/min and 5/min respectively. Impairment or lossof especially the slower oscillatory mode has been linked todevelopment of diabetes. There exists models explaining the fasteroscillations, but the mechanism behind the slower ones remainsuncertain.

Calcium levels are linked to ATP levels, which are directlycoupled to the glucose level by the glycolytic pathway, an ancientbiochemical chain reaction present in almost all living organisms in

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which glucose is degraded and part of its energy is harvested in theform of ATP. Our hypothesis is that the glycolysis itself is oscillatoryin certain parameter ranges, and is responsible for the slow oscillations.This conjecture stems from the experimentally verified presence ofthe muscle isoform of the enzyme phosphofructokinase (PFK), whichis activated by its product. Auto-catalytic reactions are known toexhibit oscillatory behavior.

We have constructed a model of the pancreatic glycolysis[Westermark and Lansner, 2001]. At the foundation of this model lieequations describing the fluxes over the different reactions of thepathway. Special care has been taken in formulating these equationsin order for their parameters to be operationally well defined andeasily inferred from experimental data. Rather than optimizing theparameters to fixed values, we identify their physiologically plausibleranges, due to the experimental inaccuracies and natural biologicalvariability. The ranges are obtained from extensive literature studies.We then scan our constrained parameter space and observe thebehavior of our model. Our results explain how the experimentallyobserved ranges of glucose levels that induce oscillations occur, andmap out the most important factors which influence these ranges. Wealso propose a hypothesis on a biochemical mechanism, which canstabilize the frequency of the oscillations.

Modeling of Biochemical Mechanisms Underlying LearningJeanette Hellgren Kotaleski

Classical conditioning of the eye-blink response, a model system forlearning in the cerebellum, requires a specific temporal intervalbetween conditioned stimulus (CS) and unconditioned stimulus (US).Cellular correlates of classical conditioning include activation of Pro-tein Kinase C (PKC) in Purkinje cells in the cerebellum, which receiveinformation about the CS and US via parallel fibers (PFs) and climbingfibers (CFs), respectively. To evaluate to what extent biochemicalinteractions within the Purkinje cell may explain the temporal sensitiv-ity, a model of the synergistic activation of PKC by Ca, diacylglycerol(DAG) and arachidonic acid (AA) was developed [Yang et al., 2000][Yang et al., 2001]. Ca elevation is due to CF activation and IP3-induced Ca release (IICR). DAG and IP3 production results from PFactivation, while AA results from Ca-dependent phospholipase A2activation.

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A significant increase in PKC activation is found when PF inputprecedes CF input by 0.1 to 3 s. Simulations show that this temporalsensitivity of PKC is due to the requirement for overlapping AA, DAG,and Ca signals. The sensitivity of IICR to the temporal relation betweenPF-induced IP3 elevation and CF-induced Ca elevation, together withthe unique buffering system of Purkinje cells significantly contributeto amplifying the Ca signal. The model's behavior is of potentialrelevance in explaining associative learning, where animal behaviordepends on temporal relationships between stimuli.

Modeling and UnderstandingRobustness of Genomic Control SystemsErik Aurell

This project concerns modeling and understanding the robustness ofgenomic control systems. The stability of the lysogenic state in phagelambda, a paradigmatic model of a bistable genetic switch, has beenrelated to a first exit problem in a non-potential drift field with noise[Aurell and Sneppen, 2002]. The standard biochemical model of theswitch has been shown not to be robust against small parameterchanges, although exhibiting high stability at some set of reasonableparameter values.

References[Aurell and Sneppen, 2002] Aurell, E. and Sneppen, K., (2002).

Epigenetics as a First Exit Problem. Phys. Rev. Lett. 88: 048101[Björklund et al., 2000] Björklund, A., Lansner, A., and Grill, W. E.,

(2000). Glucose-induced Ca2+i abnormalities in human pancreatic islets: important role of over-stimulation. Diabetes 49(11):1840-1848.

[Dickson et al., 2000] Dickson, C. T., Magistretti, J., Shalinsky,M. H., Fransén, E., Hasselmo, M. E., and Alonso, A. A., (2000).Properties and Role of Ih in the Pacing of Subthreshold Oscillationsin Entorhinal Cortex Layer II Neurons. J. Neurophysiol. 83:2562-2579.

[Djurfeldt et al., 2000] Djurfeldt, M., Ekeberg, Ö., and Graybiel,A. M., (2000). Cortex-Basal Ganglia interaction and attractorstates. Neurocomputing 38-40: 573-579.

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[Fagergren et al., 2000] Fagergren, A., Ekeberg, Ö., and Forssberg,H., (2000). Precision Grip Force Dynamics: a System Identification Approach. IEEE Transactions on Biomedical Engineering 47(10):1366-1375.

[Fagergren et al., 2001a] Fagergren, A., Ekeberg, Ö., and Forssberg,H., (2001). Supraspinal Motor Control Signals Calculated fromHuman Precision Grip Behavior. 31st Annual Meeting, Societyfor Neuroscience. 300.8. Abstract.

[Fagergren et al., 2001b] Fagergren, A., Ekeberg, Ö., and Forssberg,H., (2001). Motor control strategies for correcting an inaccurately programmed movement: model predictions derived from human behavior. Manuscript.

[Fransén et al., 2000] Fransén, E., Alonso, A. A., and Hasselmo,M. E., (2000). Cellular and Synaptic Mechanisms of MatchEnhancment and Supression in DMS Working Memory TasksInvolving Entorhinal Cortex. Soc. Neurosci. Abstr. 596.6.

[Fransén et al., 2001b] Fransén, E., Alonso, A. A., and Hasselmo,M.E., (2001). Network mechanisms of non-match enhancement,suppression and repetition in delayed matching tasks involvingentorhinal cortex working memory function. Soc. Neurosci. Abstr.852.10.

[Fransén et al., 2001c] Fransén, E., Alonso, A. A., andHasselmo, M. E., (2001). Entorhinal Neuronal Activity DuringDelayed Matching Tasks May Depend Upon Muscarinic InducedNon-specific Cation Current ICANM. Neurocomputing 38-40: 601-606.

[Fransén et al., 2001a] Fransén, E., Alonso, A. A., and Hasselmo,M. E., (2001). Simulations of the role of the muscarinic-activatedcalcium-sensitive non-specific cation current INCM in entorhinalneuronal activity during delayed matching tasks. J. Neurosci. Inpress.

[Hammarlund and Ekeberg, 1998] Hammarlund, P., and Ekeberg, Ö., (1998). Large Neural Network Simulations on Multiple Hardware Platforms. J. Comp. Neurosci. 5: 443-459.

[Hasselmo et al., 2000] Hasselmo, M. E., Fransén, E., Dickson,C. T., and Alonso, A. A., (2000). Computational Modeling ofEntorhinal Cortex. Annals NY Acad. Sci. 911: 418-446.

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[Hellgren Kotaleski and Lansner, 1999] Hellgren Kotaleski, J. andLansner, A. (1999). Modeling Cellular Processes – Bioinformaticsbeyond Sequences. TRITA-NA-P9906, Stockholm, PSCI atNADA, KTH.

[Hellgren Kotaleski et al., 2001] Hellgren Kotaleski, J., Lester, D.,and Blackwell, K. T., (2001). Subcellular interactions betweenparallel fibre and climbing fibre signals in Purkinje cells predictsensitivity of classical conditioning to interstimulus interval. Sub-mitted.

[Hellgren Kotaleski and Blackwell, 2001] Kotaleski, J. H., andBlackwell, K. T., (2001). Sensitivity to interstimulus interval dueto calcium interactions in the Purkinje cell spines. Neuro-computing. In press.

[Houk et al., 1995] Houk, J. C., Adams, J. L., and Barto, A. G., Modelsof Information Processing in the Basal Ganglia, chapter A modelof how the basal ganglia generate and use neural signals that predictreinforcement, pages 249-270, M.I.T. Press, Cambridge, U.S.A.,1995.

[Johansson, 2001] Johansson, C., (2001). A Study of InteractingBayesian Recurrent Neural Networks with Incremental Learning.TRITA-NA-E0110, Dept. Numerical Analysis and ComputerScience, KTH.

[Johansson et al., 2001] Johansson, C., Sandberg, A., and Lansner,A., (2001). A Capacity Study of a Bayesian Neural Network with Hypercolumns. TRITA-NA-P0120, Dept. Numerical Analysis and Computer Science, KTH.

[Johansson and Lansner 2001] Johansson, C., and Lansner, A., (2001). A Parallel Implementation of a Bayesian Neural Network with Hypercolumns. TRITA-NA-P0121, Dept. Numerical Analysis and Computer Science, KTH.

[Kozlov et al., 2001a] Kozlov, A., Hellgren Kotaleski, J., Grillner,S., and Lansner, A., (2001). Modeling of substance P and 5-HTinduced synaptic plasticity in the lamprey spinal CPG - conse-quences for network pattern generation. J. Comput. Neurosci. 11:183-200.

[Kozlov et al., 2001b] Kozlov, A., Aurell, E., Orlovsky, G. N.,Deliagina, T. G., Zelenin, P. V. Hellgren-Kotaleski, J. andGrillner, S. (2001). Modeling postural control in lamprey. BiolCybernetics 84(5): 323-330.

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[Kozlov et al., 2001c] Kozlov, A., Fagerstedt, K. P., Ullén, F., andAurell, E., (2001). Turning behavior in lamprey in response todescending unilateral commands: Experiments and modeling.Neurocomputing 38-40: 1373-1378.

[Kozlov et al., 2001d] Kozlov, A., Ullén, K. F., Fagerstedt, P.,Aurell, E., Lansner, A., and Grillner, S., (2001). Turning behaviorin lamprey in response to descending unilateral commands. Biol.Cybernetics 86: 1-14.

[Lansner et al., 2000] Lansner, A., Sandberg, A., and Petersson,K. M., (2000). On Forgetful Attractor Memories. ANNIMAB-1,Gothenburg, Sweden. Invited.

[Lansner and Sandberg, 2001] Lansner, A., and Sandberg, A., (2001).Functionality and Performance of Brain-Inspired Neural Networks.NOLTA 2001, Zao, Sendai, Japan. 501-504.

[Orre et al., 2000] Orre, R. Lansner, A., Bate, A., and Lindquist, M.,(2000). Bayesian neural networks with confidence estimations applied to data mining. Computational Statistics and DataAnalysis 34: 473-493.

[Sandberg et al., 1999] Sandberg, A., Lansner, A., Peterson, K. M.,and Ekeberg, Ö., (1999). A Palimpsest Memory based on anIncremental Bayesian Learning Rule. Neurocomputing 32-33: 987-994.

[Sandberg et al., 2001a] Sandberg, A., Lansner, A., Petersson, K.-M.,and Ekeberg, Ö., (2001). Bayesian attractor networks with incremental learning. Network: Computation in neural systems, 13, 179-194.

[Sandberg and Lansner] Sandberg, A., and Lansner, A., SynapticDepression as an Intrinsic Driver of Reinstatement Dynamics inan Attractor Network. Neurocomputing. To appear.

[Sandberg et al., 2001b] Sandberg, A., Petersson, K. M., andLansner, A., (2001). Selective Enhancement of Recall throughPlasticity Modulation in an Autoassociative Memory.Neurocomputing 38-40: 867-873.

[Schultz et al., 1997] Schultz, W., Dayan, P. and Montague, P.R., Aneural substrate of prediction and reward, 1997, Science,275:1593-1599.

[Wahlgren and Lansner, 2001] Wahlgren, N., and Lansner, A., (2001). Biological evaluation of a Hebbian-Bayesian learning rule. Neurocomputing 38-40: 433-438.

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[Westermark and Lansner, 2001] Westermark, P., and Lansner, A.,(2001). A Model of Phosphofructokinase and Glycolytic Oscill-ations in the Pancreatic b-cell. Submitted.

[Yang et al., 2000] Yang, K.-H., Hellgren Kotaleski, J., andBlackwell, K. T., (2000). The role of protein kinase C in the tem-poral specificity of Purkinje cells. Annual Meeting of the Societyfor Neuroscience. 718.

[Yang et al., 2001] Yang, K.-H., Hellgren Kotaleski, J., andBlackwell, K. T., (2001). The role of protein kinase C in thebiochemical pathway of classical conditioning. Neurocomputing38-40: 79-85.

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Stefan Arnborg, Johan Håstad, Viggo Kann

The objective of the research in Theoretical Computer Science is toinvestigate methods of efficient computation in a mathematicallyprecise sense, and to find lower bounds on the computational resourcesrequired for a computation. The types of computations studied areeither chosen for their tractability or for their importance in practicalapplications. We have also recently started activities in applicationsand foundations of uncertainty management and intelligent data analy-sis. The different areas of study are described below.

During the period 1993-2001 the group has been supported byNUTEK, BFR, TFR, NFR, SSF, HSFR, VR, GG, VINNOVA, SAAB,VOLVO, and FOI.

More information about the research group and our researchareas can be found on the web at <www.nada.kth.se/theory>.

Approximation AlgorithmsJohan Håstad, Viggo Kann, Jonas Holmerin, Gunnar Andersson, LarsEngebretsen

A large number of the known NP-complete problems are in factoptimization problems, and for some of these optimization problemsthere are fast approximation algorithms, that is, algorithms guaran-teed to find close-to-optimal solutions. For instance, the travelingsalesman problem in the plane is NP-complete, but in polynomialtime it can be solved approximately within every constant; for anyε >0 one can find a trip of length at most 1+ε times the shortest trippossible. On the other hand, some NP-complete problems are ex-tremely hard to approximate. For instance, unless all problems in NPcan be solved in probabilistic polynomial time, the maximum inde-pendent set problem cannot, in polynomial time, be approximatedwithin n1-ε for any ε>0, where n is the number of vertices in the inputgraph.

The main topic of this project is to investigate to what extentthe optimum value of important NP-complete problems can beapproximated efficiently. This naturally involves two types ofactivities, namely to prove positive and negative approximation results.

www.nada.kth.se/theory

Theoretical Computer Science, TCS

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To get a positive result − an upper bound of the approximability −one constructs an algorithm, proves that it is efficient, and approx-imates the problem within a certain accuracy. To get a negative result− a lower bound − one usually proves that approximating a givenproblem remains NP-hard.

Andersson and Engebretsen have completed their Ph.D. theseswithin this area [Andersson, 2000] and [Engebretsen, 2000]. A numberof papers should also be mentioned.

One of the major open problems is to show that it is NP-hard tocolor a three-colorable graph with any constant number of colors.This remains open, but the analogous statement for hypergraphs withedge size 4 is true [Guruswami et al., 2001].

Based on slightly stronger but universally accepted assumptions,the above result on an independent set can be improved; ε can be ofthe form O((log log n)-1/2)[Engebretsen and Holmerin, 2000].

The traveling salesman problem, also mentioned above, hasmany interesting special cases, and one is given by problems wherethe distance of any two points is bounded from above. Improved lowerbounds for this problem have been proved [Engebretsen and Karpinski,2001].

On the positive side, some approximability results have beenestablished. The first deals with constraint satisfaction problems whereeach variable appears a bounded number of times, and the latter dealswith over-determined systems of linear equations where each equationonly contains two variables [Håstad, 2000][Andersson et al., 2001].

The underlying technique for most of the moderninapproximability results is the concept of probabilistically checkableproofs. The most novel such proof within the last couple of years wasproposed in 2000 by Samorodnitsky and Trevisan.We haveparticipated in several simplifications and extensions of this result.Håstad and Wigderson gave a simpler proof, Håstad and Khot madesure that the verifier always accepts a correct proof, and Engebretsenextended the results to non-Boolean domains [Håstad and Wigderson,2001][Håstad and Khot, 2001][Engebretsen, 2001].

Kann and Crescenzi have compiled a list of the best lower andupper bounds known for more than two hundred well-studied NP-complete optimization problems. We try to collect all new results inthe wide area of approximation in order to keep the problem listupdated. The list is included in a new textbook on approximation

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(Ausiello, Crescenzi, Gambosi, Kann, Marchetti Spaccamela, andProtasi), and is also available on the Web at www.nada.kth.se/~viggo/problemlist.

Complexity and CryptographyJohan Håstad, Mikael Goldmann, Mårten Trolin, Gustav Hast, AnnaRedz, Rafael Pass

Computational complexity involves studying the amount ofcomputational resources required to solve certain types of problems.Resources typically considered are the time (number of steps) of analgorithm, or the size and depth of Boolean circuits.

Some of our recent work has been along very classical lines.Investigations in approximability of optimization problems has shownthe central importance of optimally solving (over-determined) systemsof linear equations in Abelian groups. With this problem now quitewell understood, the non-Abelian case turns out to be interesting;Goldmann and Russell have proved the basic decision problem to beNP-complete [Goldmann and Russell, 2001].

On a classical problem in the comparison model Dor, Håstad,Ulfberg and Zwick have improved the lower bound for finding themedian for a natural class of algorithms [Dor, Håstad, Ulfberg andZwick, 2001].

Cryptography occupies a central position, and in this area andthe group has worked on foundational questions as well as moreapplied questions in this area. We have established that functions thatcan be used as generic hard-core predicates cannot have Fouriertransforms supported mostly on small sets. This implies, in particular,that such a function cannot be computed by very simple models ofcomputation such as small-depth circuits [Goldmann, Näslund andRussel, 2001].

Taking theoretical work to more practical use, Håstad and Näs-lund have constructed pseudo-random generators whose propertiesare based on explicit assumptions about standard symmetric blockencryption schemes, such as the newly established AdvancedEncryption Standard (AES). Unless this cryptosystem has veryundesirable properties, the output from the generator cannot besignificantly distinguished from true random numbers. A precise and

Computational complexityinvolves studying the amountof computational resourcesrequired to solve certaintypes of problems.

Cryptography occupies acentral position,...

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quantitative version of this statement is proved [Håstad and Näslund,2000, 2001].

Finally on the more applied side, Trolin (unpublished) hasproposed and analyzed a new scheme for digital money and Håstadet al. have developed a protocol for “funkspiel,” a way to covertlyalert a network that one of its components has been penetrated [Håstadet al., 2000].

DecomposabilityStefan Arnborg, Öjvind Johansson

The theory of tree-decomposable graphs became a foundation. BDDtechnology and Baysian networks, two areas with numerous appli-cations. Studies of dense decomposable graph families have beenmade, like graphs of bounded clique-width and NLC-width [Johans-son, 2001]. The first progress since 1985 in the open problem ofcomplexity of decomposition of dense decomposable families, exceptco-graphs, was obtained by Johansson in 2000, with a polynomialtime algorithm for NLC2-decomposition. An approximation algorithmfor NLC-decomposition with general k was also obtained [Johans-son, 2001a].

Formal MethodsKarl Meinke

Software testing can be seen as complementary to formal programverification, it is oriented towards locating and identifying errors, rat-her than establishing that code is error free. Surprisingly, since mostsoftware does indeed contain bugs, very few scientific results havebeen produced in this area. Our recent research has included a semanticmodel of the industry standard testing language TTCN3 based ontimed automata. We are currently pursuing research into the centralissue of test coverage, based on ideas from stochastic process theory,as well as constraint-solving algorithms for test-case generation.[Johansson and Meinke, 2001].

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Computational BiologyJens Lagergren, Lars Arvestad, Lars Ivansson

The number of organisms with a known genome is steadily increasing.Computational biology and bioinformatics is moving towards post-genomic issues, that is, the goal is shifting from finding genes tofinding the function of genes.

Recent advances in molecular biology have led to a variety ofbiologically motivated algorithmic problems. The disclosure of thegenome of an organism is facilitated by assembling maximum- length,directly readable stretches of DNA. This assembly is one example ofa biologically motivated algorithmic problem. Other advancesfacilitate simultaneous measurements of the activity, in terms ofmRNA levels, of thousands of genes. Together these advances havegiven and will give rise to an enormous amount of data, for which theanalyses constitute algorithmic problems. Many of the most interes-ting problems are NP-complete, and can thus be expected to be difficultto solve, but sometimes there are ways around this dilemma. Weconsider, for example, biologically meaningful, fixed-parametervariations.

One approach to revealing the function of genes is to correlatephenotype evolution with genome evolution. Genome evolution alsoprovides an opportunity to establish the correspondence between ge-nes in different genomes (orthology analysis), which can be used totranslate knowledge of gene function in a model organism to thecorresponding knowledge for humans.

In the genome, the genes evolve through nucleotide substi-tutions. The evolution of the genome is also shaped by a multitude ofother evolutionary events acting at different organizational levels.Larger genome segments are affected by processes such as duplication,lateral transfer (where a segment of an organism's genome is transferedto the genome of another organism), inversion, transposition, deletion,and insertion. Being able to identify genes that have been lateralytransfered and count the number of lateral transfer events is crucialfor the resolution of the existance of a tree of life. Finally, the wholegenome is influenced by speciation and hybridization of organismlineages (where a new species is created by the fusion of two organismsgenomes). The complexity of genome evolution poses a serious chal-lenge in developing mathematical models and algorithms.

Recent advances in mole-cular biology have led to avariety of biologically moti-vated algorithmic problems.

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A classical problem in computational biology is that of inferring theevolutionary history of a set of species. The evolutionary history isrepresented by a phylogenetic tree. Due to duplications and lateraltransfers, gene trees (i.e., evolutionary trees for gene families) andthe corresponding species trees may often disagree. We have studiedthe algorithmic problem: for a given a set of disagreeing gene trees,find the species tree that explains the disagrement using a minmumnumber of duplications [Hallet and Lagergren, 2000]. We have alsogiven a mathematically rigid and biologically sound model for late-ral transfers and a fixed parameter algorithm for the problem: given agene tree and a species tree, find the minimum number of lateraltransfers that explains the difference between the given trees [Halletand Lagergren, 2001].

Algorithms in Language EngineeringViggo Kann, Johnny Bigert, Johan Carlberger, Jonas Sjöbergh

Our goal in this project is to combine algorithms that have a solidmathematical foundation with linguistic knowledge in order toconstruct tools for Swedish text processing; tools that are both accurateand capable of handling large amounts of data without speeddegradation. We have earlier successfully constructed efficient toolsfor Swedish hyphenation, Swedish spelling error detection andcorrection, Swedish word inflection, and Swedish part-of-speechtagging.

Currently we are focusing on Swedish grammar checking andproof reading in cooperation with the natural language processinggroup at IPLAB. We have constructed Granska, which is a surfacesyntactic hybrid system using both statistical and linguistical methodsfor checking and correcting Swedish text [Carlberger et al., 2000].

A vital part of Granska is our new object-oriented rule languagefor describing grammatical errors using rules consisting of regularexpressions, words, part-of-speech tags, help rules, and recursive rules.We have put much effort into optimizing the tagging and rule matchingusing good algorithms and data structures. The rule set is precompiledinto a form that makes the rule matching very fast.

We have constructed and evaluated rules for all error types hand-led by other grammar checkers for Swedish and also for the verycommon Swedish error type split compounds, which is an intrinsically

...to construct tools for Swe-dish text processing...

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hard error to find by computers. Although this was not an originalobjective of the rule language, it turned out to be very useful indetecting phrases such as NP and PP with good precision. ThereforeGranska become not just a grammar checking system, but a generalhigh level text processing platform for Swedish [Knutsson et al., 2001].

Intelligent Data Analysis and VisualizationStefan Arnborg, Johannes Keukelaar

In a project within the Centre for Geoinformatics, Johannes Keukelaardevelops methods for rough set classification using a visual language.This technique is useful, for instance, when a number of qualitativelydifferent classifications of geographical areas are merged, [Keukelaaret al., 2000][Ahlqvist et al., 2000]. A system for discovery ofgoverning equations for time series data using genetic programmingwas developed [Whigham and Keukelaar 2001].

Design and Architecture ofBrain Image Database ManagersPer Svensson, Jesper Fredriksson

This Ph.D. research project combines research objectives from twosubject areas.

• The project currently contributes to the Neuroinformatics andBINS analysis center projects and has previously contributed tothe now-completed ECHBD Image Database project.• In the field of Scientific Database Management, the projectinvestigates and improves current methodology in the areas ofinteractivity, functionality, and network access of large-scale imagedatabases.

There is no mature methodology for management and analysis oflarge 3D spatial and spatiotemporal image databases. Therefore, oneobjective of the project is to evaluate and refine this kind of emergingmethodology. We investigate the use of mediator technology (theAMOS II system), in combination with specialized image databasetechnology (RasDaMan) and standard off-the-shelf relational databasetechnology (IBM DB2) in a large and complex scientific databaseenvironment.

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The Neurogenerator project is supported by an EC Quality of Lifegrant, and the Brain Image Neuroinformatics System (BINS) by aSwedish Strategic Research Foundation (SSF) grant. The EuropeanComputerized Human Brain Database (ECHBD) project wassupported by an EC Biotech grant. All three projects were initiatedand are led by Professor Per Roland at the Human Brain ResearchDivision of Karolinska Institutet (KI) in Stockholm. Partners in thecurrent projects include the KI Human Brain research division, theNADA, CVAP, and TCS groups at KTH, the KTH PDC super-computing center, the Uppsala University Database Laboratory(UDBL), the Forwiss research group at the Technical University inMunich, and the software company Active Knowledge, also in Mun-ich.

The project's main objectives are:• to perform research on architecture, design, and usage qualityaspects of brain image databases and related data analysismanagement systems, and• to analyze and develop new methodology to improvemanagement and scientific use of large neuroinformatics imagedatabases.

The project has a neuroinformatics usage perspective, which involves:• management of very large, inhomogeneous data collections where3D raw PET and fMRI brain images are primary data objects;• generation under close user control of homogeneous databasesof preprocessed, "statistical" images;• logical and statistical queries on sets of such images, producingpedigrees of secondary image data;• storage and access performance requirements arising fromproduction, analysis, and interactive display of 2D and 3D images;and• Web distribution and access of images.

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From this usage perspective, the project investigates:• multidatabase, mediated architecture and data modeling issues,• concepts, and options;• data-mining methods for functional PET and MRI brain imagery;• use of a supercomputing center as a backend storage andcomputing resource; and• performance issues in storage, access, query, and display of brainimagery.

During 1998 and 1999, a brain image database system, based on theRasDaMan raster database manager and the O2 object-orienteddatabase management system, was developed for the ECHBD project.The first working version of the system was made available to theECHBD project partners in September 1999.

Our next task was to design the overall architecture of the BINSraw image database system. About a year later, the Neurogeneratorproject started, whose aim is to create a common database environmentfor distribution to several brain database research centers. In thisproject, we have been responsible for the overall system architectureand the design of the workflow management subsystem. We are nowabout halfway through the latter project, where a powerful brain imageanalysis center is taking shape.

The AMORose ProjectPer Svensson, Karim Oukbir

The AMORose project has three main goals:

1. To construct a prototype Geographical Information System (GIS)based on extensible object-relational database technology. The de-sign is based on Active Mediator Object System (AMOS II), desig-ned and built by Tore Risch and his group. The data model and querylanguage of AMOS II is suitable for extension with spatial abstractdata types.

2. To base the design on a robust implementation of spatial operators.GISs include sets of geometric operations that are used to performanalyses and other computations on geographical databases. In currentGIS products, these operations are not implemented in a robust man-

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ner and may produce inconsistent results. AMORose uses the robustabstract spatial data type implementation that is provided by the Roselibrary [Güting and Schneeider, 1995].

3. To permit representation and processing of the uncertainty inhe-rent in spatial data. To be able to state the amount of uncertainty inthe result of an analysis, one needs to collect, properly represent, andcorrectly propagate information about the uncertainty in both spatiallocation and attribute values. In the current version of AMORose,both kinds of uncertainty are represented as rough sets.

The project combines state-of-the-art type-extensible object-orienteddatabase technology developed in the AMOS research program [Fahland Risch, 1998] with robust plane geometric computational algebradeveloped in the ROSE program [Güting and Schneeider, 1995].

Using this experimental GIS platform, investigations of spatialobject representation and spatial analysis operations are carried out.Parts of the technology have been used in an investigation of roughset classification [Ahlqvist et al., 2000].

The Rose library has been further developed. In 1998, a simplefirst version of AMORose was developed by Xiaolin Qin (a guestresearcher at NADA). This implementation was based on the AMOSmain-memory object database handler [Fahl and Risch, 1998].

A second version of AMORose using AMOS II, a moreadvanced version of AMOS, was implemented in 2000. Initialfunctionality demonstrations have been made with this version. Itincludes transparent dynamic memory management of spatial objectsand is the first version with a capacity to store large spatial datasets,although it does not yet contain query optimization or spatial indexing.

Collaboration between Ola Ahlqvist (Department of PhysicalGeography, Stockholm University), Johannes Keukelaar and KarimOukbir (Department of Numerical Analysis and Computer Science,Royal Institute of Technology, Stockholm) has led to publications inthis area [Ahlqvist et al., 2000][Keukelaar et al., 2000]. A paper,intended for journal publication, is being written on the combineduse of fuzzy and rough set theory as a way to represent spatialuncertainty.

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Inference from DataStefan Arnborg

Under this heading, we study fundamental and applied inferenceproblems. The fundamental studies are related to ongoing discussionsabout the role and possible adaptation of Bayesianism to applicationsin semi-intelligent computer systems [Arnborg and Sjödin 2000,2001]. The applied studies concern the possibilities for advanced data-mining techniques to help investigating major medical puzzles, likeexplanation and treatment of schizophrenia [Arnborg et al., 2000].

Information is also available on the Web at <www.ki.se/cns/hubin>.

Decision SupportStefan Arnborg, Joel Brynielsson, Klas Wallenius

There are large uncertainties regarding the kind of tasks that militaryforces will encounter in the future. The emphasis will be on threatsthat include terrorism and disasters, rather than on the large invasionthat was previously considered the main issue. Flexibility is thekeyword in dealing with situations that might be classified as betweenwar and peace. The commanders must be able to combine and useavailable armed units, as well as other resources, to achieve the goalsof a given task. To solve tasks not known in advance, one ought tolook for ways of planning and executing operations that do not dependon the actual kind of resources that will be used. The science of Com-mand and Control, C2, shows promising possibilities to achieve suchflexible and general methods. Further motivations for general C2methods suitable for different situations include reduced costs fortechnical development and training, as well as faster and betterdecision-making.

The research activities within the area of Decision Support aimto provide tools for C2 based on Bayesian approaches to decisiontheory and knowledge representation. These tools include supportfor situation awareness, information quality, and decision analysis[Arnborg et al., 2000], [Wallenius, 2000][Wallenius, 2000a][Bergmanand Wallenius, 2001] [Brynielsson and Granlund, 2001]. One specific

www.nada.kth.se/theory/projects/decision _support.html.

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contribution is the Game Environment for Command and ControlOperations, GECCO, which is a generic platform for gaming. GECCOis provided to the research community as open source [Brynielssonand Wallenius, 2001], see also <www.nada.kth.se/theory/gecco>

ReferencesTheses[Andersson, 2000] Andersson, G., (2000), Some New Randomized

Approximation Algorithms, PhD thesis.[Engebretsen, 2000] Engebretsen, L., (2000), Approximate Constraint

Satisfaction, PhD thesis.[Ivansson, 2000] Ivansson, L., (2000), Computational Aspects of

Radiation Hybrid Mapping, PhD thesis.[Johansson, 2001] Johansson, Ö., (2001), Graph Decomposition Using

Node Labels, PhD thesis.[Oukbir, 2001] Oukbir, K., (2001), A Database Query Language for

Uncertain Spatial Data, Licentiate thesis, TRITA-NA-0121, Dept. of Numerical Analysis and Computer Science, Royal Institute ofTechnology, Stockholm.

Journal publications[Ahlqvist et al., 2000] Ahlqvist, O., Keukelaar, J. H. D., and Oukbir,

K. (2000), Rough classification and accuracy assessment, Inter-nat. J. Geographical Information Science, 14:5, 475-496.

[Alimonti. and Kann, 2000] Alimonti, P. and Kann, V. (2000), Hardness of approximating problems on cubic graphs, Theoretical Computer Science, 237, 123-134.

[Andersson et al., 2001] Andersson, G., Engebretsen, L., and Håstad, J. (2001), A new way of using semidefinite programming with applications to linear equations mod p, J. Algorithms 39:2,162-204.

[Aumann et al., 2001] Y. Aumann, J., Håstad, M., Rabin, and M., Su-dan (2001),Linear consistency testing, Journal of Computer andSystem Sciences, 62, 589-607.

[Arnborg et al., 2000] Arnborg, S., Agartz, I., Nordström, M., Hall,H., and Sedvall, G., (2000), Human Brain Informatics - Under-standing Causes of Mental Illness, ERCIM News No.43, October2000.

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[Dor et al., 2001] D. Dor, J. Håstad, S., Ulfberg, and U., Zwick (2001),On lower bounds for selecting the median, SIAM Journal onDiscrete Mathematics, 14, 299-311.

[Eriksson et al., 2001] Eriksson, H., Eriksson, K., Karlander, J., Svens-son, L., and Wästlund, J. (2001), Sorting a bridge hand, DiscreteMathematics, in print.

[Eriksen et al., 2000] Eriksen, N., Eriksson, H., and Eriksson, K.(2000), Diagonal checker-jumping and Eulerian numbers for color-signed permutations, Electr. J. Combinatorics.

[Eriksson and Löfdahl, 2001] Eriksson, H., and Löfdahl, M., (2001), An algorithm for resolving 2π ambiguities in interferometricmeasurements by use of multiple wavelengths, Optical Enginee-ring, in print.

[Eriksson et al., 2001b] Eriksson, H., Eriksson, K., and Sjöstrand, J.(2001), A note on the lamps problem, Advances of Mathematics,in print.

[Fredriksson et al., 2001] Fredriksson, J., Svensson, P., and Risch, T.(2001), Mediator-based evolutionary design and development ofimage meta-analysis environments, Int. J. Intelli-gent InformationSystems, 17, 301-322.

[Goldmann et al., 2001] Goldmann, M., Näslund, M., and Russell, A. (2001), Complexity bounds on general hard-core predicates, J. Cryptology, 14, 177-195.

[Håstad, 2000] Håstad (2000), J., On bounded occurrence constraint satisfaction, Infor mation Processing Letters, 74:1,1-6.

[Håstad et al., 2001] Håstad, J., Ivansson, L., and Lagergren, J., (2001),Fitting points on the real line and its application to RH mapping,J. Algorithms, to appear.

[Håstad et al., 2001b] Håstad, J., Linusson, S., and Wästlund, J.,(2001), A smaller sleeping bag for a baby snake, Discrete andComputational Geometry, 26, 173-181.

[Johansson, 2000] Johansson, Ö., (2000), NLC2-decomposition in

polynomial time, Internat. J. Foundations of Computer Science,11:3, 373-395.

[Kann et al., 2001] Kann, V., Domeij, R., Hollman, J., Tillenius, M., Uhlirova, L., Wimmer, G., Altmann, G., and Koehler, R., (2001), Implementation aspects and applications of a spelling correction algorithm, Quantitative Linguistics, 60.

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[Roland et al., 2001] Roland, P., Svensson G., Lindeberg, T., Risch,T., Baumann, P., Dehmel, A., Fredriksson, J., Halldorsson, H., Forsberg, L., Young, Y., Zilles, K. (2001), A database generator forhuman brain imaging, Trends in Neurosciences 24:10, 562-564.

Conference publications[Arnborg et al., 2000] Arnborg, S., Artman, H., Brynielsson, J., and

Wallenius, K. (2000), Information awareness in command andcontrol: Precision, quality, utility, 3rd Int. Conference on Infor-mation Fusion, Paris, France, ThB 1, 25-32.

[Arnborg and Sjödin, 2000] Arnborg, S., and Sjödin, G., (2000), Bayes Rules in Finite Models, Proc.\ European Conference on Artificial Intelligence, Berlin, 571-575.

[Arnborg and Sjödin, 2000b] Arnborg, S., and Sjödin, G., (2000), Onthe foundations of Bayesianism, 20th Int. Workshop on BayesianInference and Maximum Entropy Methods in Science and Enginee-ring, Gif-sur-Yvette, 61-71.

[Bergman and Wallenius, 2001] Bergman, N., and Wallenius, K.,(2001), Providing the common view of the situation - the WASPapproach, Information Management Challenges in AchievingCoalition Interoperability, Quebec City, Canada.

[Brynielsson and Wallenius, 2001] Brynielsson, J., and Wallenius,K., (2001), Game environment for command and control opera-tions (GECCO), Cognitive Research with Microworlds, Granada,Spain.

[Brynielsson and Granlund, 2001] Brynielsson, J., and Granlund, R.,(2001), Assistance in decision making: Decision help and decisionanalysis, 6th Int. Command and Contro Research and TechnologySymposium, U.S. Naval Academy, Annapolis, Maryland, USA.

[Carlberger and Kann, 2000] Carlberger, J., and Kann, V., (2000),Some applications of a statistical tagger for Swedish, 4thConference of the International Quantitative Linguistics Associa-tion (Qualico 2000), 51-52.

[Engebretsen, 2001] Engebretsen, L., (2001), The non-approximabilityof non-Boolean predicates, RANDOM 2001, LNCS 2129,241-248.

[Engebretsen and Holmerin, 2000] Engebretsen, L., and HolmerinJ., (2000), Clique is hard to approximate within n1-o(1), ICALP 2000,LNCS 1853, 2-12.

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[Engebretsen and Karpinski, 2001], Engebretsen, L., and Karpinski,M., (2001), Approximation hardness of TSP with bounded metrics,ICALP 2001, LNCS 2076, 201-212.

[Eriksson et al., 2000] Eriksson, H., Eriksson, K., and Sjöstrand, J.(2000), Expected number of inversions after a sequence of random adjacent transpositions, 12th Conference on Formal Power Series and Algebraic Combinatorics, 677-685.

[Fredriksson and Svensson, 2001] Fredriksson, J., and Svensson, P.,(2001), Evolutionary design and development of image meta-analysis environments based on object-relational database mediatortechnology, Scientific and Statistical Database ManagementSystems 2001, Proceedings IEEE Comp. Soc., 190-199.

[Goldmann and Russell, 2000] Goldmann, M., and Russell, A., (2000),Spectral bounds on general hard-core predicates, STACS 2000,LNCS1770, 614-625.

[Guruswami et al., 2000] Guruswami, V., Håstad, J., and Sudan, M.,(2000), Hardness of approximate hypergraph coloring, 41st AnnualIEEE Symposium on Foundations of Computer Science, 149-158.

[Guruswami et al., 2000b] Guruswami, V., Håstad, J., Sudan , M.,and Zuckerman, D., (2000), Combinatorial bounds for list deco-ding, invited paper at 38th Annual Allerton Conference ofCommunication,Control and Computing, October 2000.

[Hallett and Lagergren, 2001] Hallett, M.T., and Lagergren, J., (2001),Efficient algorithms for lateral gene transfer problems,RECOMB´01, 149-156.

[Hallett and Lagergren, 2000] Hallett, M.T., and Lagergren, J., (2000),Hunting for functionally analogous genes, FSTTCS´00, 465 - 476.

[Hallett and Lagergren, 2000b] Hallett, M.T. and Lagergren, J (2000),New algorithms for the duplication- loss model, RECOMB´00,138-146.

[Håstad, 2000] Håstad, J., (2000), Which NP-hard optimizationproblems admit non-trivial efficient approximation algorithms,ICALP 2000 (invited presentation), Lecture Notes in ComputerScience, 1Theoretical Computer Science.

[Håstad et al., 2000] Håstad, J., Jonsson, J., Juels, A., and Yung, M.,(2000), Funkspiel schemes: An alternative to conventionaltamper resistance, 7th ACM Conference on Computer Comm-unications Security, 125-133.

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[Håstad and Khoy, 2001] Håstad, J., and Khot, D., (2001),Query efficient PCPs with perfect completeness, accepted for pre-sentation at 42nd Annual IEEE Symposium on Foundations ofComputer Science.

[Håstad and Näslund, 2000] Håstad, J., and Näslund, M., (2000), BMGL: Synchronous key-stream generator with provable security,1st Open NESSIE Workshop.

[Håstad and Näslund, 2001] Håstad, J., and Näslund, M., (2001),Practical construction and analysis of pseudo-randomness primi-tives, accepted for presentation at ASIA-crypt 2001.

[Håstad and Wigderson, 2001] Håstad, J., and Wigderson, A., (2001),Simple analysis of graph tests for linearity and PCP, ComputationalComplexity 2001.

[Johansson, 2001] Johansson, Ö., (2001), n-Approximative NLCk-

decomposition in O(n2k+1) time, WG 2001.[Keukelaar et al., 2000] Keukelaar, J. H. D., Ahlqvist, O.,

and Oukbir, K., (2000), Representing uncertainty in geographicaldata,SIRC 2000, Dunedin, New Zealand.

[Knutsson et al., 2001] Knutsson, O., Carlberger, and J., Kann, V.,(2001), An object-oriented rule language for high level text proces-sing, Nordiska datorlingvistikdagarna, NoDaLiDa’01, Uppsala,May 2001.

[Trolin, 2001] Trolin, M., (2001), The shortest vector problem in lattices with many cycles, Cryptography and Lattices Conference(CaLC) 2001, LNCS 2146, 194-205.

[Wallenius, 2000] Wallenius, K., (2000), A network centric info-structure for the Swedish armed forces, Milinf 2000, Enköping,Sweden.

[Wallenius, 2000a] Wallenius, K., (2000a), Use of modern informa-tion technology: WASP – a common view of the situation, TechnetEurope, 21st AFCEA Europe Symposium and Exposition, Prague,Czech Republic.

[Whigham and Keukelaar, 2001] Whigham, P. A., and Keukelaar, J. H. D., (2001), Evolving structure – optimising content, CEC 2001.

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Miscellaneous[Carlberger et al., 2000] Carlberger, J., Domeij, R., Kann, V., and

Knutsson, O., (2000), A Swedish grammar checker, submitted.[Engebretsen and Holmerin, 2001]Engebretsen, L., and Holmerin, J.,

(2001), Towards optimal lower bounds for Clique and ChromaticNumber, Technical report TR01-003, ECCC.

[Goldmann and Russell, 2001] Goldmann, M., and Russell, A., (2001),The Complexity of Solving Equations over Finite Groups, sub-mitted.

[Johansson and Meinke, 2001] Johansson, H., and Meinke, K., (2001),An operational semantics for TTCN3, manuscript.

Background[Güting and Schneider, 1995] Güting R. H., Schneider M. (1995),

Realm-Based Spatial Data Types: The ROSE Algebra, The VLDBJournal, 4, 243-286.

[Fahl and Risch, 1998] Fahl., Risch T., (1998), AMOS II: Introduction,EDSLAB, Department of Computer Science Linköping Univer-sity.

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Ongoing Research inHuman-computer

Interaction

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Kerstin Severinson Eklundh

Introduction to IPLAB’s Research AreasIPLAB (The Interaction and Presentation Laboratory) has beenengaged in interdisciplinary research in human-computer interactionsince 1985. The group currently consists of about 30 people, including20 graduate students. IPLAB is responsible for NADA’s education inhuman-computer interaction at both undergraduate and graduatelevels.

IPLAB collaborates closely with CID (The Centre for User-Oriented System Design), an industrial competence center hosted byNADA, involving interdisciplinary design and development projects.About five of IPLAB’s graduate students are engaged in CID’s re-search.

IPLAB’s research falls mainly into the areas of computer-supported cooperative work, computer-supported writing andlanguage technology, user-centered system development, and human-robot interaction. The first three areas were established during the1980’s, whereas the last one was initiated as late as in 1997, as a partof IPLAB’s engagement in the HMI Graduate School.

The funding for IPLAB’s research during 2000-2001 has comefrom SSF (The Foundation for Strategic Research), KFB (The Swe-dish Transport and Communications Research Board), AMS (TheSwedish Labour Market Board), RALF, NUTEK and recently VIN-NOVA. Industrial partners are engaged mainly through theirinvolvement in the CID center.

Since 1997, IPLAB has been one of the partner institutions ofthe Graduate School for Human-Machine Interaction, a collaborationbetween KTH and the University of Linköping. IPLAB’s involvementin the HMI program has led to the recruitment of several graduatestudents as well as the development of a number of new graduatecourses in human-computer interaction at NADA. Summer schoolswithin HMI were held by NADA in both 1999 and 2001.

The first Nordic conference on human-computer interaction,NordiCHI’2000, was hosted by IPLAB and CID and took place atKTH in October 2000.

Interaction andPresentation Laboratory, IPLAB

IPLAB is responsible forNADA’s education in human-computer interaction

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Computer-Supported Cooperative WorkFrom 1997 through 2001, a major part of IPLAB’s research in CSCWhas been performed within the group “KnowHow,” funded by KFBand HMI. It includes several separate projects with a common focuson network-based collaboration in knowledge-intensive professions.A synthesis of perspectives and studies related to these projects isgiven in [Severinson Eklundh et al., 2001b].

Collaborative Writing and Document DesignCollaborative writing is a central research topic within CSCW, and italso continues the traditions of research on computer-supported writingat IPLAB. The work includes both empirical studies and design ofWeb-based collaboration tools for the purpose of reviewing docu-ments.

An interview study has been conducted with the purpose toreveal collaborative writing practices, focusing on reviewing phasesin writing [Kim and Severinson Eklundh, 2001]. An interesting fin-ding was that some writers had begun to use tools for representingchanges in text, or change representation tools, while the issue ofusage of these tools had so far largely been neglected by researchers.Against this background, two experimental studies were carried outto investigate how people understand and use change representationtools in the context of collaboration between a writer and a reviewer[Kim and Severinson Eklundh, 2002] [Kim, 2000]. The studiescompared two ways of representing changes, indication and display,and two ways of collaborating, writer- and reviewer-initiativecollaborations. The benefits and limitations of use of these tools werealso discussed.

A second important finding from the interview study was that anetwork environment is an important factor for successful coll-aboration. We have explored the potential of the World Wide Web assuch an environment for collaborative writing. As a continuation ofwork previously performed in collaboration with CID (the DomainHelp project), an environment has been designed that allows users toshare documents and to carry on an asynchronous dialogue ofcomments during the reviewing process [Rodriguez, 2001]. Thisgeneric tool has been further developed into a prototype for coll-aborative writing, Collaboracio. In this environment, writers can share,comment on, and modify a set of HTML documents, constituting a

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joint writing task. The set of comments evolve into a dialogue, visiblein its entirety to the user. The participants’ awareness of each others’activities and the current state of the document is supported throughe-mail messages. Both tools have been evaluated in a series of casestudies [Rodriguez, 2001]. An in-depth study has also been made of asmall group of writers who reviewed their documents together usingCollaboracio [Kim, 2002]. By using an analytic frameworkspecifically designed for the discourse of reviewing, the evolvingdialogue of comments was described in relation to the writing task.The study has also revealed the trade-offs of dialogues versus anno-tation in the design and usage of commenting functions.

Managing the Information Flowin Computer-Mediated CommunicationElectronic mail (e-mail) is one of the most widespread computerapplications today. The use of e-mail within workplaces may involvevarious problems: an increasing amount of messages that overwhelmsusers, systems that are too complex for naive users and at the sametime do not support the needs of experienced users. These problemswere treated in a Ph.D. thesis by Olle Bälter (1998). This work hasconsiderable public interest, as shown by numerous presentations inpapers, magazines, and on the radio.

Recently, Bälter’s mathematical model estimating the time usedfor moving messages to folders and retrieving them again has beenrefined [Bälter, 2000a]. The model indicates that usage of more than30 mail folders is questionable from a time efficiency perspective formany users. Hands-on advice on how to replace an old e-mail systemwith a new one, a common situation for many companies andorganizations, was presented in [Bälter, 2000b]. The paper is basedon a study of a technical company that replaced two mainframe e-mail systems with Lotus Notes. Among the observed problems arethe difficulties with transferring old stored messages and their infor-mation structure to the new system.

Managers often have special problems with e-mail [Bälter,2000c]. On one hand, e-mail is an efficient tool to handle much oftheir communication; on the other hand, managers can drown inmessages. Managers use email to handle the increase in comm-unication that follows a promotion. Despite e-mail’s asynchronousnature, half of the e-mail users in the study, including managers,

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allowed incoming e-mail messages to interrupt other tasks. Conside-ring the time required for context switches, this can be a serious wasteof time.

The collaboration with Lotus Development in Cambridge, MA,USA, has resulted in a report on Bifrost, a categorization system forincoming messages [Bälter, 2001a]. Bifrost gives users support tofocus on the important messages first. It is based on experiences ofusers that receive more e-mail messages than they can handle.

A four-year longitudinal study of e-mail usage among non-technical users in a medical service organization was concluded inthe beginning of 2001 [Bälter 2001b]. E-mail had a positive influenceon the organization and reduced computer anxiety dramatically.However, mass mailings from within the organization were a causeof annoyance for individual users, and were also a negative economicalfactor for the organization.

Knowledge Sharing within OrganizationsAn area of growing concern is how technology can support knowledgedevelopment within organizations. As an alternative to solutions whereattempts are made to store knowledge in an organizational memory,it is of interest to explore support for people to reach others whopossess relevant knowledge. An ethnographic field study at a Swe-dish consultancy firm brought out this alternative [Groth, 2000] [Grothand Bowers, 2001]. One major finding from this study is that suppor-ting people in finding information is a situated matter depending onwho is available at the moment. This finding has changed our focusfrom knowledge systems supporting people in others’ skills andexperiences to awareness systems supporting people in finding outabout others’ availability and activities. Well-structured informationabout what project people work on, etc. is still important for knowingabout others’ skills, but knowing about others’ availability andactivities is even more important in order to facilitate social contactbetween people when finding information.

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Coordination and Technology in Newsroom WorkA new project funded by RALF/VINNOVA investigates the role oftechnology for decision processes and coordination in newsroomwork. Preliminary observations from the central office of a dailynewspaper show that several different forms of communication areused to coordinate the editorial work (formal meetings, spontaneousmeetings in the office areas, telephone calls, e-mail, faxes, and writtensummaries. Different media are used for different purposes, and theyare chosen with respect to constraints derived from technology andvarious possibilities for immediate feedback in direct communication.Faxes are used for sending papers along with short comments in themargins. E-mail is used for longer messages, assignments, and simplediscussions. More sensitive issues, negative criticism, and longerdiscussions are handled by telephone and direct communicationbetween the parties involved. The results of the investigation thusshow that different forms of coordination interact with each other ina complex way.

Using Technology for Coordination of Work in Control RoomsFollowing our workplace studies of coordination and technology inair traffic control [Normark, 2000] [Berntsson and Normark, 2000],we became involved in a field study at SOS Alarm, the company thatreceives all calls made to the emergency phone number 112 [Helge-son et al, 2000]. SOS Alarm is responsible for dispatch and monitoringof ambulances, and redirecting emergency calls (e.g., to the police).Our studies focus on the use of artifacts and technology in coordinatingwork in the emergency dispatch center. The air traffic control studygave examples of the “traditional” way of working in control rooms− using paper flight strips, radar, and a vast range of sources − towardswhich the controllers orient themselves. The SOS study is an exampleof a more computerized setting, where most artifacts are combinedinto one system and one screen, providing a central focus of attention.

Research has shown that coordinated work usually depends onthe visibility of the work of others. In control rooms, there is anextensive need for updates, but there is also a need to reduce infor-mation to a basic level. Analysis of the sense-making exchangebetween caller and operator demonstrates that the verbal, non-computerized, communication is still very much needed. Knowingthe area so that the right information can be entered into the system is

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important as well as understanding what kind of information thedispatcher will need in order to make a dispatch.

The Use of Synchronous Text-BasedEnvironments for Teacher Professional DevelopmentA study has been made of the use of a synchronous text-basedcommunication environment (a so-called “Moo”) by teachersattending a real professional training session [Cerratto, 2001a,b][Waern and Cerratto, 2001]. The focus is on teachers’ activity andprimarily on the appropriation process of the communication artifact.In the course studied, professional teachers who are interested inlearning about the integration of technology in the classroom aresupposed to reach insights and understanding about their off-lineteaching experiences. There are some prerequisites for communicationto serve this purpose. First, the participants have to share and maintaina focus in their dialogue. Secondly, they have to be able to establishmutual understanding with respect to possible solutions and co-constructing agreed solutions.

The question addressed here is how synchronous text-basedenvironments may fulfill these requirements. The results from bothquantitative and qualitative analyses indicate that teachers mainlyappropriate the synchronous text-based communication artifact formaintaining relationships − a task that was not a primary goal of thecourse. However, they did not use the artifact for argumentation orany deeper negotiation of meaning [Cerratto, 2001]. Suggestions aregiven for the design of an artifact for collaborative learning purposesand for the re-design of the educational activity.

Virtual Environments for CollaborationComputer environments are increasingly based on the use of multiplemodalities, such as sound, pictures, video, and even haptic feedbackthat supports the sense of touch. This has actualized issues about therole of various modalities in collaborative tasks.

In an experiment, the effect of haptic force feedback onperformance in a collaborative virtual environment was tested [Sallnäset al., 2000][Sallnäs, 2000]. In addition, effects on the subjective per-ception of being virtually present at a distant location and beingsocially present with a collaborator at that place were investigated.The haptic force feedback device, PHANToM, was used to convey to

...effects on the subjectiveperception of being virtuallypresent at a distant location...

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the user a sense of touch and feel of virtual objects regarding form,weight friction, and collision forces. An interface was developed thatenabled participants to feel and manipulate virtual objects together ina collaborative virtual environment. Results showed that haptic forcefeedback significantly improved task performance and perceived taskperformance. Furthermore, haptic force feedback enhanced the senseof virtual presence in the environment (“being there”) while therewere no significant effects on social presence (“being together”).

Different communication media were investigated in anotherstudy. The aim was to investigate to what extent collaboration in three-dimensional desktop environments is affected by an audio comm-unication channel or video connection in comparison to text chat.Besides the aim of investigating the effect of the communicationmedium, the effect of three dimensions was also investigated. Somesubjects collaborated in a Web environment instead of a three-dimensional desktop environment. Dependent variables in the expe-riment were perceived task performance, perceived virtual presence,and perceived social presence. These were measured by question-naires. Furthermore, dependent variables measured objectively, weretime to perform task, frequency of words, and words used per second.Subjects collaborated in pairs and performed a decision-making tasktogether. Results show that communicating by text-chat is significantlycruder in both a three-dimensional desktop environment and in a Webenvironment in comparison to an audio or video communicationchannel. Using text-chat also results in people feeling significantlyless virtually and socially present in comparison to an audio or videocommunication channel. There was a significant difference regardingwords used per second between video, audio, and text-chat. Onaverage, people used the most words and spent more time in the vi-deo condition than in the audio condition, which might suggest thataudio is the most efficient medium whereas video is the most enjoyablemedium. Text-chat proved to be both slow and taciturn.

Figure 1. One subject’sperspective on the informa-tion in the CVE in ActiveWorlds showing the othersubject,posters and links toQuickTime movie clips withaudio.

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A Master’s project is under way that investigates hand-over situationsin a three-dimensional desktop virtual environment with haptic forcefeedback. Two different collaborative environments are beingdeveloped and tested; one is designed to be more controlled, so thatusers feel more certain that the hand-over is successful, whereas thesecond is less controlled. A question that is interesting to investigateis how the feeling of trust is affected by the differences in functionalityin the two environments. The aim is also to investigate if there arequantitative differences in actual performance in the two environments.

As collaborative virtual environments have become more com-mon, usability issues in their design have emerged. One of these issuesis whether all participants in a shared virtual environment need to seeexactly the same objects, represented in the same way. Manyapplications apparently will benefit from loosening the consistencyof presentation. A particular line of work is concerned with allowingdifferent participants to view different more-or-less overlappingsubsets of a common universe of data, and let each participant tailorthe local view, while still allowing some degree of shared understan-ding of what user is viewing what data. [Jää-Aro and Snowdon, 2001].

Other Topics in CSCWIPLAB’s early research in computer-supported cooperative work inthe 1990s focused on the design of groupware tools. Some of theideas behind this work have been further developed by CID research-ers. The concept of a collaborative desktop developed in this periodhas recently been a topic in Konrad Tollmar’s dissertation [Tollmar,2001]. An important issue throughout this work has been how to sup-port group awareness of others’ activities in computer-mediatedcollaborative work. As a follow-up on previous work on Web-basedawareness systems [Tollmar et al., 1996], a simple vision-based sys-tem has recently been designed and evaluated. This system transformsa physical sign-in board into a Web page that is easily accessiblethroughout the IPLAB environment [Garcia, 2001][De Frutos, 2001].

Writing and Language TechnologyComputer-supported writing has been a research topic at IPLAB sincethe 1980’s. A significant part of the work has focused on writers’

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problems in composing and reviewing long texts on computer screens.More recently, a major part of the research has concerned computer-supported collaborative writing, and language tools for writers.

Overview and the Paper ModelA special interest has been devoted to writers’ need for a globalperspective of a lengthy text. The paper model of computer-basedwriting has been developed previously at IPLAB as an alternative tothe usual scroll-window text presentation. The text is presented onseparate pages, which can be directly manipulated by the writer in away similar to paper sheets. This model is designed to provide anoverview as well as to support the writer’s spatial memory of thetext. In her licentiate thesis, Ann Fatton [Fatton, 2000] explored thepotential of the paper model in two longitudinal case studies. Thestudy gave interesting input into the design of a writing system basedon the model. The results also led to the conclusion that the need fora global perspective is an integrated part of writing processes, situatedin the moment-to-moment text creation and reviewing contexts, andthis cannot be confined to a special stage or an isolated function of awriting tool.

Revision trackingAs a part of the research on writing, IPLAB has been engaged in thedesign of computer tools for the observation and analysis of writingprocesses. This has resulted in the development of keystroke-registration tools, and in an editor-independent notation for revisionsperformed during a writing session (S-notation; Kollberg, 1998). Therevision tracking tool Trace-it, which is based on S-notation, hasattracted international interest and has been used by several research-ers outside KTH [Kollberg and Severinson Eklundh, 2001]. Recentlythe tool has been applied to the identification of revision episodes,for the purpose of studying discourse-level revision strategies.

Language Tools for WritersThe design and use of language tools for writers has been a focus ofstudy for IPLAB since about 1992. The grammar-checking tool “Gran-ska” developed within the group was originally designed within aNUTEK project. Since 1998 this work has been performed togetherwith the TCS group at NADA. The project has also included

...collaborative writing, andlanguage tools for writers.

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collaboration with the Swedish Language Council and the Depart-ment of Linguistics at Göteborg University. A new project is currentlybeing started with support from VINNOVA, focusing on the use ofgrammar checking for users with Swedish as a second language.

Refinement of Grammar-checking RulesThe grammar-checking rules in Granska have recently been refined,trained, and evaluated. This work was done to complement the studiesin Ola Knutsson’s licentiate thesis [Knutsson 2001a]. The error typesthat Granska tries to recognize differ a lot both in occurrences and inthe depth of language analysis required to detect them. Many errorswithin the verb chain can be recognized with limited syntacticknowledge, but disagreement errors in predicative sets the limits forsyntactic analysis (Knutsson 2001c). The latter error type needs somekind of semantic analysis, and in the future Granska must deal withsemantic interpretation of words to some extent.

EvaluationGranska was evaluated on five text genres comprising about 200 000words [Knutsson 2001a] [Knutsson 2001c]. The detections and dia-gnoses from Granska on these texts were manually examined. Theresult indicates differences of the outcome of the grammar checkingbetween text genres. In the evaluation on texts from popular science,nine of ten errors were found, and five of ten error reports were correct.In student texts, the results were almost the opposite; four of ten errorswere found, and seven of ten error reports were correct. Oneexplanation of the results is that it is difficult to detect errors in acontext that also contains errors, which is the case with student texts.

User StudyFor the data and measurements in the textual evaluation to have anyvalidity, they must be complemented with user studies. Therefore asmall user study with Granska and a commercial grammar checkerwas conducted [Knutsson, 2001a]. Some users in the study seem toonly need the detection from a grammar checker, and they can makethe correction in the text by themselves. False alarms from theprograms seem to be of variable difficulty for the users. If the alarmconcerns easily judged errors, such as spelling errors, users usually

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do not change the text. However, if more complicated error types areinvolved, users might follow the advice from a grammar checker evenif it is wrong.

Granska Language EngineGranska has evolved to a general language engine for analysis ofauthentic texts. Rules for general text processing have been developed,and the rule language in Granska has also been extended for thesepurposes [Knutsson et al., 2001]. With these extensions, Granska canwork as a shallow syntactic parser in any language technologyapplication. The Granska language engine is in the process of beingintegrated in a text-summarization tool developed at IPLAB[Dalianis, 2000].

Automatic Text Summarization andOther Information- Retrieval TechniquesIPLAB’s research in language technology has recently been extendedto problems in text summarization and extraction, with a wide rangeof applications within information retrieval and Web-oriented tools.The SeaSum project is an effort to build the first automatic textsummarizer for Swedish (SweSum).

Automatic text summarization is the technique wherein acomputer summarizes a text. A text is entered into the computer anda summarized text is returned, which is a non-redundant extract fromthe original text. Automatic text summarization is based on statistic,linguistic, and heuristic methods [Dalianis, 2000]. SweSum uses aSwedish keyword lexicon containing 700 000 possible entries pointingat 40 000 base keywords [Carlberger and Kann, 1999]. The keywordsbelong to the so-called open class words (nouns, adjectives, adverbs).The summarization system calculates the frequency of the keywordsin the text, which sentences they are present in, and where thesesentences are in the text. It considers if the text is tagged with a boldtext tag, a first paragraph tag, or numerical values. All this informa-tion is compiled and used to summarize the original text.

SweSum is a state-of-the-art summarizer that has 84 percentaccuracy at 40 percent summarization level [Dalianis and Hassel,2001]. SweSum is now also available for English, Spanish, Frenchand German.

...an effort to build the firstautomatic text summarizerfor Swedish

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We are currently working on pronoun resolution to make thesummarized text more coherent. Incoherencies occur specifically whenthe summaries are below 30% of the original texts and when a prono-minal reference “hangs freely” with no reference in the text. Pronounresolution will resolve the pronouns in the text and replace them withthe original noun when necessary.

Within the SeaSum project (which is sponsored by NUTEK)we have also used human language technology techniques, such asstemming and index-based spelling support applied on search enginesto increase the relevance of the found documents [Carlberger et al.,2001].

A very important part of research with human languagetechnology is to have a corpus for testing and evaluation. Thereforewe have built a tool, the NewsAgent, that automatically downloadsSwedish news text from the Internet to build such a corpus [Hassel,2001]. The NewsAgent also has a user interface, the NewsGuide,which is a testbed for various tools, such as automatic textsummarization, stemming techniques, and named entity recognition[Dalianis and Åström, 2001].

Within the SeaSum project we have disseminated all the abovetechniques to the industry and society with the aim of obtaining moreinterest and support to the research area. A spin-off company EurolingAB has also been founded to commercialize the techniques.

User-Centered System DevelopmentIPLAB has a strong background in the area of user-centered systemdesign since the early 1980s, when the group was formed. Later, thistradition was manifested in the establishment of CID, the Centre forUser Oriented IT Design, where user orientation of developmentprojects is one of several major research areas in collaboration withindustry.

Procurement CompetenceProcurement competence is one of the latest projects at IPLAB. Rat-her than focusing on the actual interaction between user and computeror methods to involve users in the design processes during systemdevelopment, the project focuses on how the procurer defines andlays ground for usability issues during system development. Theproject is funded by VINNOVA.

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Organizational goals and usability are assumed, but seldom explicitlystated, when procuring computer systems. Procurement competenceexplores the procurement process from usability and organizationalstandpoints in order to develop understanding and models for goodprocurement practices. Apart from running over time as well as bud-get, it is common knowledge that large amounts of unplanneddevelopment activities are consequences of neglected usability issuesearly in projects. Developing procurement competence must deal withthose issues. One main issue is to find the connection between themanagement view on usability and how the users should be involved.So far research has focused on different forms of user involvementand usability assessments, all from the producer’s perspective.Procurement competence is devoted to exploring the powers of user-centeredness and usability from the inception of system developmentprojects. The goal is to produce a practical and theoretically groundedprocurement model, which takes the procurer’s perspective and isbased on the users’ needs and actual system use. Procurementcompetence expects to contribute with knowledge and experiencefrom case studies and field experimentation, which will help procurersdemand and formulate user-centred processes.

So far the project has studied one system development fromthe perspective of communication between the procurer and theproducer [Borgström et al., 2001]. The project has also arranged aworkshop on procurement for people from industry as well as a semi-nar for VINNOVA, where different actors within human-computerinteraction discussed and reflected upon the issues mentioned here.

IT-use and Accessibility forCommunication in Distributed GroupsThe aim with this pre-study is to understand the synchronous meetingsituation for small groups of knowledge workers (managers, teachers,librarians, researchers) performing real tasks in real settings. Theanalysis will include activities to be performed in a context includingdifferent tools supporting the activity. Results from the initial analy-sis will influence the development of the technology and will point atexisting problems and demands from its users.

Our approach performing field studies is cooperative design.This means that we collaborate with small groups in natural settings.The focus of study is synchronous and formal meetings in smallgroups.

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Results suggest that the audio medium is very important, and someof the problems encountered could be minimized or solved bytechnical improvements, such as avoiding echo effects. If the audioand video lag can be made smaller, the mediated communication canbe much improved. From the studies, we also found that the spatialrelationships among participants in face-to-face meetings are not atall applied in DVC [Lantz, 2001a]. In studies of mediated meetingsin collaborative virtual environments, it has been shown that the spa-tial relations can be a support for things like turn-taking [Lantz, 2001b].

Human-Robot InteractionIPLAB’s research about human-robot interaction is carried out as partof the HMI Graduate School, and in collaboration with CAS. Themain research issue is how to design user interaction with intelligentservice robots which are moving around in people’s everyday environ-ment. This includes several different problems, such as analyzingusers’ activities, finding appropriate interaction models, dialogue de-sign, and usability criteria for service robots.

Design of a Fetch-and-Carry Robot for Motion-Impaired UsersRecently, the work performed has been related to the design andevaluation of a fetch-and-carry robot for motion-impaired people inan office environment [Severinson Eklundh et al., 2001]. This projectis funded by the Swedish Labor Market Board (AMS). A user-cente-red approach has been followed, including task analysis and severaliterations of prototyping and user testing [Green et al., 2000]. Theproject has resulted in a working robot prototype, designed to enablethe transportation of light objects. For user interaction with the robot,a graphical interface and a speech interface have been designed. Tosupport interaction when the user is mobile, a simplified graphicalinterface on a small portable device has also been constructed[Hüttenrauch and Norman, 2001]. In a current longitudinal field studyat IPLAB, the robot’s design is being evaluated in a natural officesetting.

Human-Robot DialogueThe design and development of spoken dialogue is an important fieldof investigation in human-robot interaction. We are currently designingspoken dialogues for commanding office robots. The work departs

...how to design userinteraction with intelligentservice robots,...

Figure 2: The robot platformis a Nomadic Super Scout II,extended with a specially de-signed top including atransportation compartment.

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from different scenarios and possible dialogues derived from thephysical and spatial requirements on the user’s task. When analyzingthe data from users’ interaction with the prototype system, an importantresult is that relevant feedback is crucial for enabling a successfuldialogue with a robot [Green and Severinson Eklundh, 2001]. It seemsespecially important to enable low-level visual feedback on the robot’sstate, for example, by the use of life-like characters or visual displays.In our current robot prototype, ala life-like character (Cero) is placedon the robot’s front. It can give dialogue feedback through simplegestures, and it also gives the user a sense of direction. In future work,we will also investigate what other types of interface modalities couldadd in terms of providing feedback and making the behavior of therobot more transparent to the user.

Physical Life-Like CharactersIn a future scenario when more and more electronic equipment offersvoice-control as an option, ease of use will be crucial for avoidingcognitive overload. This can be achieved by using models for spokendialogue based on human behavior and intuition. We have beeninvestigating a model for interaction with spoken language interfacesthat supports heterogeneous tasks. This model is based on the idea ofusing a “family” of life-like characters [Green, 2001]. The propertiesof these characters are based on psychological and linguistic princip-les of human natural language interaction. The general idea is thathuman-like characters signal human natural language behavior, suchas the ability of understanding and producing speech. By using certainvisual cues, familiar to everyone, we can display important featuresof the speech interface to the users.

Figure 3: CERO, the Co-operative Embodied RobotOperator has four servos thatare controlled using a micro-processor. The design with-out eyes reflects the fact thatthe robot has no vision capa-bilities. Placed upon the ro-bot platform, the body andthe face give the user a senseof direction.

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Other Research Areas

Object-Oriented Programming and DesignThere is a long tradition at IPLAB of interest in object-orientedprogramming and design. Recently this work has been focused ondesign patterns, involving development and description of program-ming tools for distributed interactive applications for cooperativework. In his thesis, Björn Eiderbäck defines a framework of high-level mechanisms for the interactive distribution and sharing of in-formation, founded on the object-oriented paradigm [Eiderbäck,2001]. The mechanisms are extensions of the existing class library ofa Smalltalk environment. The resulting system allows rapiddevelopment and easy experimentation with many interactivetechniques.

Perceptual Features for Computer Graphics and VisualizationThis project aims at investigating the importance of perception forcomputer graphics and visualization and is performed by Lars Kjell-dahl in cooperation with Bo Schenkman from ACREO.

The quality of algorithms and presentations on a screen doesnot only depend on time and memory efficiency. What is actuallyperceived by the observer is also crucial. In the last few years, per-ception has become an important field for graphics and visualizationresearch; although in practice it always has influenced these areas.The use of color has been investigated in three studies on color per-ception. In the first study on color temperature [Schenkman and Kjell-dahl, 1999] the interaction between colors on a computer screen wasstudied and the importance of the surroundings, for example, the screencovering, was revealed. The preferred color temperature of the pictureson the screen differed when the screen was illuminated with differentillumination color temperatures. A second study investigated the dif-ferent effects of interaction between different colour hues. A thirdstudy has been conducted to examine the dependence of geometricdistance between the colored areas [Kjelldahl and Schenkman, 2001].

Apart from the theoretical understanding of color perception,the practical aim is to contribute to the knowledge on how to choosecolors in pictures on a screen for different applications.

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[Schenkman and Kjelldahl, 1999]Schenkman, B., & Kjelldahl, L.,(1999) Preferred colour temperature on a colour screen, Displays20 (1999), pp 73-81.

[Severinson Eklundh et al., 2001a] Severinson Eklundh, K., Espmark,E., Green, A., Hüttenrauch, H., Norman, M., & Oestreicher, L.,(2001a) Användaranpassad utformning av en “fetch-and-carry”-robot för funktionshindrade i arbetslivet. Technical Report TRITA-NA-P0110, NADA, KTH.

[Severinson Eklundh et al., 2001b] Severinson Eklundh, K., Groth, K., Hedman, A., Lantz, A., Rodriguez, H., & Sallnäs, E-L., (2001b)The World Wide Web as a social infrastructure for knowledge-oriented work. In H. van Oostendorp (ed.), Cognition in a digitalworld. Law rence Erlbaum Associates, to appear.

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[Tollmar, 2001] Tollmar, K., (2001) Towards CSCW design in theScandinavian tradition. Doctoral dissertation, TRITA-NA-0131,NADA, KTH.

[Waern and Cerratto, 2000] Waern, Y., & Cerratto, T., (2000). Problems in Orchestrating MOO Activity. In: Proceedings of the Digital Documents Track, Digital Education and Culture, Thirty-Fourth Hawaii International Conference on System Sciences (HICSS-34). IEEE, January 3-6, 2001, Maui, Hawaii.

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Ongoing Research inMedia Technology

and Graphic Arts

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Nils Enlund, Roger Wallis

The research group for Media Technology and Graphic Arts isconcerned with research in technology and methods that support hu-man communication over distances in time and space.

Within this large and eclectic multidisciplinary field, we havechosen to focus on three research areas and, especially, on theirintersections.• Graphic arts production – the technology and methods supporting

printed communication• Digital media – the design and use of new, digital communication

media. As a recent special application area, the use of interactivemedia in learning processes has been addressed

• Business development in the media industry – the influence of newtechnology on media business and industry developments

Research is carried out in a large number of related, limited projectswith various funding sources. Because much of the research is carriedout in intersecting fields, it is often difficult to designate a specificarea to a research project. In the following, the main research projectsof the research group during 2000 and 2001 have been groupedaccording to their strongest mutual relationships.

Graphic Arts Production

Production Management In Commercial PrintingThis is one in a series of projects concerning production and processmanagement in media production, which has been one of the mainstrengths of our research group since 1993.

Through close cooperation between industry and academic re-search, the project attempts to improve process controllability andcompetitiveness in the commercial printing and publishing industry.The project analyzes production processes and workflows in selectedcompanies; develops tools and methods for process analysis andbenchmarking; designs general models and methods for integrated,

Media Technologyand Graphic Arts, MEDIA

www.gt.kth.se

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global production management; and evaluates protocols used incomputer-based systems for active production tracking, dynamicresource allocation, and real-time production management. It will alsodevelop a general requirements checklist for management informa-tion systems in the printing industry and evaluate an implementationof such a system.

The project will also increase technical and scientific knowledgeand skills within the printing and publishing industry, directly withinthe participating companies and indirectly through the increased know-how of the research group, dissipated through courses given at KTH.The project started in the fall of 1996 and will be concluded in early2002. The project has had the financial support of a group of Swedishprinting companies and industry organizations.

Relationships between Product Structureand Productivity in Printing and MailroomEarlier research indicates a clear relationship between productstructure and productivity in newspaper production. The design ofthe product, number of pages, sections, and inserts, as well as the useof color on the pages, will affect productivity. This research projectwill categorize and analyze the causes of production stoppages inpress and mailroom. Further mailroom studies will be carried outbecause the available statistics concerning this are incomplete. Thestudies are carried out at two newspaper printing plants. The Swedishnational print research program T2F finances the project.

Development of Newspaper DistributionThis project about the future development of newspaper distributionstarted in March 1999 and finished at the end of 2001. The mainfocus of this project has been to find ways of improving the physicaldistribution of morning newspapers in metropolitan areas. Manyproblems related to the Scandinavian method of early morning homedelivery have been addressed: flexible and rapid updating of carrierinformation, improvement of bundling principles, carrier securityimprovements, delivery route optimisation, and the use of mobiledevices in delivery tracking and management.

As a result of the project, four scientific papers have beenwritten, three papers have been presented at conferences, and onepaper has been published in a journal. A licentiate thesis has also

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been presented [Rehn, 2001]. The project was financed by a consor-tium of newspaper delivery companies and industry organizations.Workflow Auditing in Media Production and DistributionWorkflow auditing in the newspaper industry has been an area ofresearch for many years, and it has proven to be a useful tool forimproving the quality of the production process. This project furtherdevelops this work by delving deeper into this area and also byexamining whether the same principles can be applied to other areasof media production. Subprojects involve analyzing TV newscastproduction, Web-based media, push service, and XML-basedtechnologies. The distribution process now also has new possibilitiesof workflow auditing because of the rapid development of positioningsystems and mobile communication, so this area will also be exami-ned.

Productivity and Quality in Digital Image ProcessingThe goal of the project is to improve productivity and quality in theprepress functions of these companies. Together with 11 participa-ting companies we have tested our hypothesis and implemented it invarious areas of their research. Improvements have been implementedin various areas of their operations, using different solutions. In thetransition from analogue to digital workflows, the demands on skills,organization, and network with suppliers and customers havedramatically increased. As graphic arts production tools are becomingcommodities, other players in the value system have attainedknowledge of processes that were previously reserved for graphicarts industry companies. The productivity and customer valuemeasurements have been used in business process redesign of existingworkflows. New technologies have mainly been implemented in thematerial processes. Production management systems in prepressproduction could tie all processes together and increase the possibilitiesof control while providing feedback of higher accuracy and frequency.The project is financed by the Swedish national print research pro-gram T2F.

Substrate Printability in Flexographic PrintingThe objective of this ongoing research project is to find uniform waysof measuring the printed quality in flexography and, in a second step,to be able to predict the print quality before the actual printing. This

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quantification must take into consideration the interaction betweenthe substrate characteristics and the printing parameters. Therefore,it is preferable to speak of a measurement of "printability." The methodmust be objective by eliminating human judgement and environmentalfactors, which currently often lead to interpretation and not to scientificmeasurement. To achieve these requirements of simplicity andobjectivity we need the help of a “key number”: In the investigationswe will study the credibility of such a “printability coefficient.” Theprintability coefficient is the final number resulting from the input ofmeasured quality quantifications like density, mottling, edgesharpness, cleanliness of solid area, dot gain, and deformation. Thegain of the equation will result from different steps in the project.These steps, as well as intermediate goals, can be seen: modeling ofthe print, modeling of the unprinted paper with regard to printability,and the development of a tool for the acquisition of quality inputparameters. The project is financed by the Swedish national print re-search program T2F.

Interactive Media and Multiple Channel Publishing

TAPP −−−−− Technology and Workflow in Premedia ProductionThe venturing into electronic news publishing channels in additionto the printed newspaper during recent years has lead to morecomplicated flows of information and materials. When electroniceditions were introduced as a part of newspaper publishing, they werelargely seen as technological experiments. The number of users waslimited and very little content was created solely for the new editions.This made the need for integrated and well-organized editorial andadvertising units within the newspaper company limited. The morewell-established the electronic editions have become – in particularthe Web edition – the more have the editorial and economic demandshave increased. In order to meet these demands, more people thatproduce content for the new editions are required. This, in turn, leadsto an increasing need for organizing the different desks within theeditorial unit in new ways, in order to utilize the knowledge and theskill of the personnel as optimally as possible for all editions. Innewspaper organizations with separate editorial units, the flow of in-

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formation and matter becomes complicated. Because some of theeditorial content creation work is performed in parallel, much research,creative work, and layout work is duplicated or triplicated.

In order to promote the synergy effects in newspaper production, theskills of the staff and the production tools have to be optimized. Thenew production flows that result from new editions and publishingchannels demand new organizational solutions. They might also dem-and new skills and a new kind of professional within the editorial andadvertising units. TAPP is a project that aims, with a starting-point inearlier research findings, to put together a useful model for organi-zation and technology within editorial multichannel publishing.

Questions related to the project are:• Databases for publishing in parallel media• Database-based information handling and publishing• News production in digital editorial environments• Optimizing the news process in production in parallel channels• Process and object models for news production for TV and daily

newspapers• Design of premedia systems

The project, financed by IFRA Nordic, started in 2001 and will beconcluded in early 2002. The project also cooperates with theNewsplex project at University of South Carolina.

Synergy in Multiple-Channel PublishingThis now-completed project concerns information-handling, organi-zation and technology development in companies that publish con-tent in multiple (often parallel) publishing channels. The project wasinitiated in 1997 and resulted in a licentiate thesis in 1999 [Sabel-ström, 1999] and a doctoral thesis in 2001 [Sabelström Möller, 2001].

The project was carried out as studies of a number of Swedish,European, and US newspapers and media companies, through fieldresearch and interviews with staff involved in multiple-channelpublishing.

Telepresence ProductionPresence is defined as the subjective experience of being in one placeor environment, even when one is physically situated in another.

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Sensory environment, individual preconditions, and content characte-ristics are important factors in producing a sense of presence adnreality. This project explores the methods and possibilities of producinga sense of presence and reality using primarily low-cost technology.Experiments are carried out using different types of person-to-personcommunication mediated by distance technologies. Telepresenceproduction may sometimes be an alternative to physical presence indifferent learning modes and digital networking production systems.Telepresence production research is closely related to the studies oflearning environments carried out by the research group.

The studies of presence production are also related to expression,narration, and design in the performing arts. In connection with theresearch, several installations and performances with artistic elementshave been staged, produced, and studied. A research cooperation hasbeen established with the Stockholm University College of Fine Arts.

Interactive Media in Complex Sales ProcessesThis research project concerns the use of interactive media to supportand develop complex industrial sales processes “b2b.” Is it possibleto substitute the human sales representative with a web application?Of course not – unless you restrict the meaning of “complex industrialsales processes “ considerably. There is a limit, and the aim is to findits whereabouts – and also to stretch it out by using a combination ofinteractive multimedia, human-computer interaction, interactive de-sign, dramaturgy, marketing communications, knowledge technology,and knowledge theory.

At present, the project centers on a case study of complex salesprocesses in practice at ITT Flygt, an international engineering com-pany based in Sweden. A series of interviews with sales representativesfrom different companies and different industries has also been carriedout. The intention is to explore the subject of personal selling as apractice – that is, from an epistemological point of view.

Choice of Media from Consumers’ and Producers’ PerspectiveThe project aims to explain why media consumers and producers(media companies) prefer one information carrier to another. Whatfactors – psychological, social, and communicative – determine thechoice of printed newspapers or electronical ones?

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The research consists of two main parts: media producers’ choice ofpublishing channel, and media consumers’ choice of media.The research into why media producers give priority to some of thecommunication channels includes an investigation of the following:• Media producers’ personal and organizational motives for choosing

media• Subjective judgements of organizational culture• Expectations about the media development• Attitudes to and knowledge about different kinds of media• Attribution effects on media choice• Knowledge about consumer needs and the media world of the future.

The examination of media choice from a consumer perspectiveincludes the following aspects:• Media habits and usage preferences• Significance of the individual’s age, stage of life, and lifestyle to

the choice of media• Connection between perceptual expectations and media preferences• Interpersonal communication influence on choice of the media• Saturation effects and innovation of the consumers.

The results of the study of consumers’ and producers’ choice of me-dia will later be compared to each other and to the results from theearlier study in the project News 2020, where the reasons for choosingthe information channel by managers of media organizations havebeen investigated.

The project started in January of 2001. It is supported by theSwedish national print research program T2F.

Learning and Interactive Media

Interactive Learning EnvironmentsThe project investigates the effects of technology-enhanced learningenvironments, real and virtual, on the learning process. We approachlearning as a total experience where the learning environment − thelearning space − contributes significantly to the learning process. Theenvironmental contribution can be supportive, neutral, or detrimental.In longitudinal studies, the effects of spatial factors − both in physicaland virtual space − on the learning process are invest-igated through

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a series of experiments and evaluations where students and teachersparticipate as both study objects and experimenters. The project issupported by the Wallenberg Global Learning Network (WGLN)through the KTH Learning Lab and is carried out in cooperation withStanford University.

The underlying hypothesis of the work is the view that learningtakes place in a variety of modes, each with its own requirements onspace and environment, and that the learning process can be supportedby environmental factors in physical and virtual space. In a universitysetting, we may identify the following:• performance spaces for lectures and presentations,• group spaces for project work and structured interaction,• social spaces for spontaneous interaction, and• reflective spaces for individual study and contemplation.

The research questions to be addressed in these projects are concernedboth with pedagogy and learning space design. These are some of theproblems in the realm of engineering, technology and design:• How can physical learning space be organized and designed to

allow for and sup-port a multitude of simultaneous learning modesas well as the rapid and flexible transformation of space betweendifferent modes?

• How can such a physical learning space be extended into virtualspace to allow for both synchronous and asynchronous participationat a distance?

• What technical support is necessary?

The primary pedagogical questions to be studied in relation to thedesign solutions follow:• Can learning processes and learning outcome be improved through

space design and ICT support?• Can team building and collaborative learning be reinforced through

flexible physi-cal and virtual space design and a mix of modes inlocal and distributed work?

• Is student motivation, engagement and satisfaction promoted byflexible space design with support for different learning modes?

• Can flexible communicative spaces support improved educationalquality at a lower or equal total cost?

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Folio ThinkingThis project is supported by the Wallenberg Global Learning Network(WGLN) through the KTH Learning Lab. In an effort to improve thequality of a university education, it aims to create a set of tools andmethods that will help students track and reflect upon their formaland informal learning experiences.

The project is based on the following problems:• Fragmentation of students’ learning careers at the university.• Low degree of reflection about the learning process and the social

context of education due to a vanishing learning history on the partof the student.

• Decreasing student motivation.• Lack of efficiency in how students handle information due to bad

or absent metadata systems.• Low level of student reuse of information and knowledge.

We intend to solve this problem by creating a partnership of threeuniversities (KTH, Uppsala University, Stanford University) to de-sign and build a next generation learning portfolio, along with anappropriate curriculum of practice, designed to serve core andextended students. This learning tool and the accompanying practiceswill instill the notion of “folio thinking” within five testbeds in Swedenand the United States (at KTH at the Media Technology Program).Operationally speaking, “folio thinking” is a set of behaviors and amindset that lead to four outcomes:• Improved student problem finding and solving.• Meta-discursive analysis (students conceptualizing their own

learning).• Increase in student self awareness.• Increased awareness of others’ ways of thinking.

ADIS – Integration of Adults with Disabilities intothe Labor Market through Open and Distance LearningThe EU financed project aims at developing network-based educationthat will support the learning of computer skills among adults withdisabilities.

CustomDPThe project aims to meet the growing need for up-to-date trainingmaterial for digital printing by building a system that supports thecreation, management, updating, and use of different types of trainingmaterials; and also by creating a digital printing training package thatexploits this system.

The pivotal idea in the CustomDP system is that content can becreated in relatively small units that can then be combined into largeraggregations according to the needs of a particular course or learner.The content is described by metadata, and the most suitable contentcan be found by searching the metadata database. Existing publicinitiatives and specifications are being used in system development.The project is financed by the European Commission.

Media Business and Industry Development

Media World 2020Media World 2020 is a multidisciplinary research network and thinktank focusing on new developments in media, media production, andmedia consumption. The MW2020 steering group consists ofprofessors Börje Alström, media and communication science, Mid-Sweden University; Nils Enlund, media technology, KTH; Lowe Hed-man, media and communication science, Uppsala University; andHåkan Hvitfelt, journalism, Stockholm University. The network arr-anges research seminars and has published two books. In current re-search projects, it investigates the news production strategies of me-dia companies (News 2020) and the impact of new technology onjournalistic work and journalism.

Relationships between Tangibleand Intangible Products and ServicesAn assumption common to all has been that products, services, andexperiences which can be digitized will move from physical to virtualforms, and that the shift will be linear (possibly exponential) andirreversible. It is likely that the prominence enjoyed by these mythshas masked the development of new products and services, as well asactual changes of human behaviour associated with them. In e-commerce, for example, there is already evidence of the development

of new types of personalized services, based on physical, humaninvolvement (“e-service”).

This project poses a number of questions:• Can a shift from tangible to intangible lead to a backlash, resulting

in new, often unexpected combinations of products/services andbehavioural patterns?

• Will such a shift serve to enforce or create new demands for physicalelements and physical presence?

• To what extent will interaction between users and technologicalsolutions produce new hybrid forms of the tangible/intangible?

The empirical focus is on four activity segments: the music industry,publishing (print industry), financial services, and education.

The project’s theoretical contribution will be to appraisecritically the proposition of a linear shift, through studies of alternativepatterns of change. The project thereby seeks to provide a basis foran improved understanding of how the implementation of digitaltechnology can better satisfy the needs and demands of society. Itwill also provide useful data for individuals and organizations involvedin production processes and product development in industriesexperiencing a shift from the tangible to the intangible.

RESCUE −−−−− the Renaissance Economy Strategies and Coordination for EuropeResearch in recent years has explored the “new economy,” particularlyin the USA and Europe. Applied studies have evolved to developresponses to the opportunities and threats posed by the new economy.This focuses specifically on the cluster of issues concerned with theintangible economy. It is an accompanying measure that builds onthe previous body of research and applied studies, seeking to improvesignificantly the understanding of decision-makers across Europerelating to the aspects of the intangible economy. It will also developfurther the diverse “communities of interest” in Europe relating tothe intangible economy. These communities have parallel andpotentially overlapping concerns, but their interests have not yet beenable to intermix.

This EU-funded project is concerned with the collaborativedevelopment of innovative training and development materials toaccelerate the take-up of methods and practices that will accelerate

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the implementation of the intangible economy in Europe. The growingimportance of the intangible economy can be demonstrated clearly,but it has barely begun to excite or stimulate business andgovernmental decision-makers. Decision-makers must become muchmore sensitized to the shift from tangible to intangible goods andcompetencies. The project aims to create a computer-based and aphysical network of experts, to catalyze disparate areas of businessexpertise in the intangible economy, to link the academic and busi-ness centers of expertise, and to accelerate the sharing of informationabout both good practice and the latest leading-edge practices.

E-CommerceDuring recent years, the potential for electronic commerce via theInternet has been intensively discussed. A strong vision of e-commerceas a business with great potential has been established. In themeantime, various signs of problems with e-commerce have beenobserved. The comprehensive empirical material concerningconsumers’ impressions and experiences of e-commerce indicates thatimportant qualities in the business are missing.

This project examines the potential for e-commerce, by identi-fying and analysing factors that are important for the consumers inmaking use of the new medium. Based on the results obtained, newsystems and strategies that could facilitate the interaction between e-trading companies and consumers are being studied [Persson, 2001].

Management and Organization in Media FirmsIn a series of studies, we have investigated aspects of managementand organization in media firms. Among the focus areas have beenorganizational knowledge creation, strategic management tools,product development processes, and organizational development.The project is now completed.

Tools for Eco-Efficiency in the Printing IndustryThe main objective of this study has been to develop and test workprocedures and applied tools for environmental work in the graphicarts industry, which could lead to more eco-efficient and sustainableproduction.

The following areas have been included in the research:• Evaluation of environmental management systems in order to de-

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velop future environmental work• Development of industry specific environmental indicators for the

printing industry aiming at an improved and more efficient follow-up, management, and communication of the environmental work

• Development of industry specific work procedure and tools fordesign for environment (DFE) in order to promote a focus on theproducts and their functionality in future environmental work withinthe product chain of the graphic arts industry

The industry-specific work procedures and tools that have beendeveloped are designed to help companies in the graphic artsproduction chain to quantify and assess environmental impact fromtheir activities and printed products. By using the work proceduresand tools that are industry specific and also tailored to small- andmedium-sized enterprises (SMEs), it should be possible to improvethe efficiency of environmental efforts within media companies[Enroth, 2001].

Human Resources Management and WorkingEnvironment within the Future Graphic arts and Media SectorThis project discusses the working environment and the developmentof human capital in the future graphic arts and media sector. Themain research objective is to identify the competence requirementsand characteristics for existing and potential employees in the graphicarts and media sector and, in particular, within the cross-mediapublishing and production environment of print and electronic me-dia. This goal will be implemented by taking into consideration theimplications to the sector by the application of new technologies andthe development of new electronic media. A secondary researchobjective is to study whether existing human resource managementconcepts can be efficient for the entire spectrum of organizations andenterprises of a certain industry sector as well as individuals withsome relationship to this sector. Also investigated will be whether thesector’s specific characteristics affect the application of a humanresources management strategy. Finally, research will be focused ondefinition of the characteristics of a model for human capitaldevelopment in relationship with an industry sector. The graphic artsand media sector will be used as a pilot for the model development.

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[Lindgren, 2000a] Lindgren, M., The effects of preflighting toolson the prepress process, in Bristow, J.A.: Advances in PrintingScience and Technology, Vol. 26, Leather-head, 2000, pp. 321-336.

[Lindgren, 2000b] Lindgren, M., Quality in a digital prepressworkflow, thesis for the degree of Doctor of Technology, KTH,Stockholm, 2000, p. 202.

[Lundhgren, 2000] Lundhgren, J., Bildskärm och papper sominformationsbärare – tekniska egenskaper (Screen and paper asinformation carriers – technical characteristics, in Swedish), T2FReport f-1, Tryckteknisk Forskning, Stockholm, 2000, p. 43.

[Persson, 2000a] Persson, C., Individuellt bemötande på persona-liserad webbplats (“Individual service on a personalized web site”,in Swedish), IMT Bulletinen, March 2000, p. 6.

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[Persson, 2000b] Persson, C., Wikström, S., Critical factors fore-business retailing, in Stanford-Smith, B., Kidd, P.: E-businesskey issues, applications and technologies, IOS Press, 2000, pp.824-830.

[Persson, 2001] Persson, C., Strategies for enhancing consumerinteraction in electronic retailing, thesis for the degree of Doctorof Technology, KTH, Stockholm, 2001, p.170.

[Politis, 2000a] Politis, A., Digital printing: finishing technologiesmaking digitally printed documents professional, XML Europe2000 Proceedings, Paris, 2000, pp. 977-991.

[Politis, 2000b] Politis, A., Human resources management for SMEsand independent workers within the graphic arts and media sector,MIWS Proceedings, Athens, 2000.

[Politis, 2000c] Politis, A., Graphic arts production oriented network in Greece, MIWS Proceedings, Athens, 2000.

[Politis, 2001a] Politis A. Formation of the new publishingenvironment under the aspect of common techniques for print andelectronic media processing (in Greek), To Kerdos, May 2001, pp48-49.

[Politis, 2001b] Politis A., The importance of packaging design forGreek agricultural products, Agrobusiness, Nr. 33. January 2001.12 p.

[Politis, 2001c] Politis, A., Human capital competence for digital printing, Proceedings of the DPP 2001 international conference, Antwerp, May 2001.

[Politis, 2001d] Politis, A., Exploring human capital competence within the complex cross-media publishing environment, XML Europe 2001 Proceedings, Berlin, 2001.

[Politis, 2000e] Politis, A., Human resource management strategies within the graphic arts and media sector, thesis for the degree of Licentiate of Technology, KTH, Stockholm, 2001.

[Rehn et al., 2000] Rehn, J., Stenberg, J., Hedin, B., Fällström, F.,Improving metropolitan newspaper home distribution, TAGA 2000Proceedings, Rochester, 2000, pp. 349-364.

[Rehn and Rosenqvist, 2001] Rehn, J., Rosenqvist, C., A new conceptfor managing and distributing real time content in newspaperproducts, TAGA 2001 Proceedings, Rochester, 2001, pp. 591-599.

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[Rehn and Stenberg, 2001] Rehn, J., Stenberg, J., Dynamicpreloading of newspaper bundles, TAGA 2001 Proceedings, Roch-ester, 2001, pp. 636-648.

[Rehn, 2001] Rehn, J., Information flow and physical distributionplanning in newspaper delivery, thesis for the degree of Licentiateof Technology, KTH, Stockholm, 2001, p.108.

[Rosenqvist et al., 2000] Rosenqvist, C., Turpeinen, M., Saari, T.,Development of online services under time critical conditions,TAGA 2000 Proceedings, Rochester, 2000, pp. 30-52.

[Rosenqvist, 2000] Rosenqvist, C.: Development of new mediaproducts: case studies on web, newspapers and magazines, thesisfor the degree of Doctor of Technology, KTH, Stockholm, 2000,p.120.

[Sabelström, 2000] Sabelström, K., The multimedia news reporter: technology and work processes, TAGA 2000 Proceedings, Rochester, 2000, pp. 53-66.

[Sabelström Möller and Nordqvist, 2001] Sabelström Möller, K., Nordqvist, S., Optimisation of the news process in different pub-lishing channels – a case study at Göteborgs-Posten, TAGA 2001 Proceedings, Rochester, 2001, pp. 617-635.

[Sabelström Möller, 2001a] Sabelström Möller, K., Informations-kategorier och redaktionella processer för flerkanals-publicering”(“Information categories and editorial processes in multiple channelpublishing”, in Swedish), IFRA Nordic Bulletin, June 2001, pp.1-2.

[Sabelström Möller, 2001b] Sabelström-Möller K., How to succeedwith your multiple channel publishing – content-handling,organisation and technology development in editorial departmentsfor multiple channel publishing, (in Swedish), TU-rapport, TheSwedish Newspaper Publishers Association, 2001.

[Sabelström Möller, 2001c] Sabelström Möller, K., Information categories and editorial processes in multiple channel publishing, thesis for the degree of Doctor of Technology, KTH, Stockholm, 2001, 180 p.

[Sabelström Möller, 2001d] Sabelström Möller, K., En formel förframtidens medieprodukter? (“A formula for the media productsof the future?”, in Swedish), Aktuell Grafisk Information, Nr. 338,November 2001, pp. 18-21.

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[Slimani and Gorska, 2000] Slimani, D., Gorska, E., The workingenvironment as an integrated and vital element of the organi-zational development strategy in the graphic arts industry inBristow, J.A.: Advances in Printing Science and Technology, Vol.26, Leather-head, 2000, pp. 357-373.

[Slimani, 2000a] Slimani, D., Analyses of dynamic tools forincreasing productivity, quality and customer satisfaction in sixgraphic arts and media companies, TAGA 2000 Proceedings,Rochester, 2000, pp. 365-383.

[Slimani, 2000b] Slimani, D.: Strategic management tools for graphicarts companies, thesis for the degree of Doctor of Technology,KTH, Stockholm, 2000, p.158.

[Wallin et al., 2000] Wallin, E., Lennstrand, B., Persson, C., Webmetrics – design specifications of a web-based system forpersonalization with bifurcation, TAGA 2000 Proceedings,Rochester, 2000, pp. 67-87.

[Wallis et al., 2000] Wallis, R., Klimis, G.M., Kretschmer, M.:Globalisation, Technology and the Music Ind-ustry, City Univer-sity Business School, London, 2000.

Wallis, 2000] Wallis, R., The bumpy road through the bits andbytes – the music industry and the digital environment seen throughthe eyes of a smaller collecting/protection society, in Turton, J.,Lauvaux, E. (eds.): Legal and commercial effects of digitisationon the music industry, Maklu Publishers, Apeldoorn, 2000, pp.221-231.

[Wallis and Holtham, 2000] Wallis, R., Holtham, C., From thephysical to the virtual – and back again: relationships betweentangible and intangible products, services and experiences andtheir relevance in the digital environment, Proceedings of the ThirdInternational Conference on Telecommunications and ElectronicCommerce, Dallas, 2000, pp. 147-159.

[Wallis, 2001a]Wallis, R., Global cultural industries – Trade, monopolies, cultural diversity and copyright, in Østergaard, M.(ed.): Images of the world – Globalisation and cultural divers-ity,DCCD, Copenhagen, 2001, pp. 91-97.

[Wallis, 2001b] Wallis, R., Creativity, diversity and communication.Threats and opportunities in todays global music industry, 3rdUnited Nations Conference on the Least Developed Nations,Brussels, 2001.

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[Widing, 2000] Widing, A., Låg resursförbrukning och effektivtmiljöarbete (“Low resource use and effi-cient environmentalwork”, in Swedish), IMT Bulletinen, March 2000, pp. 1-2.

Public installationsHandberg, L., et al, From atoms to bits, in R1, KTH experimental

performance space, at TIME, Stockholm, May 2000. Theinstallation was a result of projects made by students at the MediaTechnology Programme.

Handberg, L., et al, Communicative spaces, Stockholm CultureCenter – KTH, in conjunction with “The Aha Days” organized bythe Knowledge Foundation, Stockholm, October 2000.

Handberg, L., et al, ePresence, Stockholm City Hall – KTH, in conjunction with the Euro-pean Union Meeting, March 2001.

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Ongoing Research inNumerical Analysis

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Björn Engquist, Jesper Oppelstrup

The last two years have been a period of consolidation and fruitionfor the traditional research areas in fluid mechanics and wavepropagation. In an exciting development, they are now complementedby Multi-Physics and Stochastic Differential Equations withapplications to porous media flows and financial mathematics. TheNA group works with very close ties to PDC; TDB (ScientificComputing, Uppsala University); and a number of applicationoriented departments at KTH, notably Aeronautics and Mechanics,and Mathematics. External funding is supplied by VINNOVA(formerly NUTEK), TFR, SSF, NFR, and the EU.

The Parallel and Scientific Computing Institute, PSCI, a natio-nal Vinnova center of excellence, is a significant catalyst for theamalgamation and profiling of research areas. Its phase III, whichstarted July 2000, operates in the same format as previous phases,after which we expect to develop new directions for collaborativeapplied research. The PSCI projects are all carried out in collaborationwith industry, and they focus on present applications with short- tomedium-time duration. This makes it instrumental to have continuedsupport to the NA group for more basic research with long-term goals,now provided by the TFR Basic Program grant on Numerical andMathematical Study of Continuum Mechanics. The SSF supportcomes through a program on Multi-Phase Flows, the National Networkin Applied Mathematics, and the National Graduate School inScientific Computing.

The EU projects cover non-linear conservation laws andapplications of high-performance computing and visualization.

Parallelization techniques for field problems are currentlyconverging to spatial domain composition and standard message pas-sing libraries. Software for parallel architectures has become animportant theme that is developed in most projects, such ascomputational fluid dynamics and electromagnetics.

The KTH International Master’s Program in ScientificComputing hosted by the department since fall 1998 has a livelyinteraction with the research groups. The students carry out examina-

Numerical Analysis andApplications of Differential Equations, NA

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tion projects, and the researchers are heavily involved in curriculumdevelopment and teaching.

The research will be presented in the following paragraphs.The PSCI projects are described in more detail in PSCI ProgressReports 1997–1999 and 2000–2001.

• Applications to combustion, phase change problems, and semi-conductor devices are all modeled by strongly non-linear partialdifferential equations. The computational tools for these modelsinvolve grid construction, adaptation heuristics and algorithms,theoretical solution estimates, and solutions of large systems ofalgebraic equations, which are all the subject of Non-Linear PDEsand Adaptive Methods.

• As for reliable measurements, a computation needs an estimateof its accuracy to be useful. In adaptive approximation of differen-tial equations, the number of degrees of freedom is minimized, tooptimize the computational work, for a given error tolerance.Competitive computer programs for approximation of ordinarydifferential equations have had such adaptive time-step controlfor a number of years. Our goal in Adaptive Numerics for StochasticDifferential Equations is to develop reliable and efficient adaptivemethods, with mathematical foundation, for problems includingstochastic features in material science, the geosciences, andmathematical finance.

• Computational Electromagnetics is a major effort with a cleargoal to produce algorithms and software for the next generation ofindustrially applicable program packages for simulation ofelectromagnetic wave propagation. The research is now focusingon further development of the time-domain models with fast inte-gral equation methods, and ray and diffraction techniques forextending the high-frequency limit of the frequency domain modelsby hybridization.

• Multi-Phase Flows are studied in an applied PSCI project aswell as basic theoretical issues and numerical methods for movingboundary problems. The SSF project investigates the propertiesof the commonly used models that allow useful simulations,although the standard solution estimates demonstrate perturbationsthat can grow catastrophically. A new promising Level Set methodfor separated flows has reduced mass conservation errors usually

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associated with interface tracking schemes. The model forflocculated suspensions is being refined to reproduce known keyproperties of shear flows.

• In Computational Harmonic Analysis, wavelet bases are usedfor aggregating the influence of small scales on the large scales inan adaptive spatial resolution setting. The rapidly rising interestfor applications, primarily in signal processing and image treatment,both in industry and academia, is reflected in the increasing numberof collaborative projects undertaken by the wavelet group.

• Our work in Computational Physics is inspired by applicationsin materials science, and might fit equally well under the headingof “Computational Materials Science.” From simulations ofassemblies of particles – atoms in lattices, and molecules in liquids– we try to deduce macroscopically observable properties of phasechange, crystal formation, and processes such as diffusion. A fewresults from the study of Global Optimisation and the EnergyLandscapes of Dzugutov Clusters are given below. Compositematerials and porous media are often treated by ad hoc averaging.New algorithms are emerging that allow treating detailed,microscopic models with thousands of cracks, inclusions, or pores,effectively by-passing the averaging. The techniques are nowapplied to elastostatics, electrostatics, and creeping flow. We givesome spectacular examples achieved by Fast and Stable Algorithmsfor Fracture Mechanics.

• Large-Scale Computational Aerodynamics is pursued in collabo-ration with the department of Aeronautics and Mechanics. Manyflows, such as jets, phenomena relating to air intake dynamics,and high-angle of attack flows around wings, are unsteady andrequire orders of magnitude larger computing resources than dosteady flows. Parallel computing is an enabling technology formoving forward in this field, and efforts are directed to algorithmicdevelopment for industrial strength flow simulation codes, forsteady and unsteady flows, both Reynolds averaged and “largeeddy” simulations.

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Non-Linear PDE and Adaptive MethodsMichael Hanke, Gunilla Kreiss, Mattias Liefvendahl, Malin Siklosi,Björn Sjögreen, Patrik Skogqvist

The research within this subject is concentrated around three majortopics: (1) the mathematical analysis of phenomena in fluid dynamicsand the development of efficient numerical methods for their solu-tion, (2) the development of robust and reliable numerical algorithmsfor multiphysics models, and (3) the development and justification ofadaptive methods for ordinary, stochastic, and partial differentialequations.

Viscous Shock WavesKnowledge of properties of viscous shocks is important for developingaccurate numerical methods for shock problems. All shock- capturingschemes for hyperbolic conservation laws are based on artificialviscosity, and properties of the numerical methods can be derivedfrom the corresponding differential equations.

The stability of viscous shocks is a key property. Our earliertheory is expanded to problems with non-symmetric viscosity matrices[Liefvendahl and Kreiss 2001a]. The conditions for stability havebeen numerically investigated in specific cases,[Kreiss and Liefvendal,2001; Kupianen and Kreiss, 2001]. We are currently considering howto use the stability results to prove existence of shock wave solutions.A first result has been presented [Kreiss and Siklósi, 2001].

Another important aspect is the convergence rate of numericalmethods in the presence of artificial viscosity. We show that in gene-ral the order of accuracy drops in the domain downstream of a shock[Kreiss et al., 2001; Efraimsson et al, 2001]. We also demonstratethat the artificial viscosity can be designed to avoid the error increase.The analysis is based on asymptotic expansions. We are currentlyextending the results to more general problems.

Stability of Steady Incompressible FlowHow and when steady laminar flows break down and become unsteadywith subsequent possible transition to turbulence is a subject of greatimportance in applications. In physical and numerical experimentswith plane Couette flow, it has been found that there is a thresholdamplitude below which all disturbances decay. The threshold decrea-

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ses with increasing Reynolds number. A lower bound on the thresholdamplitude, including its Reynolds number dependence, was foundfrom an estimate of the resolvent [Kreiss et al.,1994]. Recently wehave have been able to sharpen the bound [Liefvendahl and Kreiss,2001b; Liefvendahl and Kreiss 2001c]. The resolvent estimate wascomputed with a spectral method based on Chebyshev polynomials[Liefvendahl, 2001].

High-Order Difference Methods for Complex FlowsWe are developing new and more accurate numerical methods forcompress-ible flows with complex structures. A typical example isshock-turbulence interaction and the deflagration to detonationtransition in combustion of gases.

When there are fine scales present in the problem, the ap-proximation should be made of high-order accuracy. On the otherhand, when shocks are present, a highly dissipative method is neededto handle discontinuities. Our approach is based on a sixth-orderaccurate finite difference scheme. The boundaries, usually problematicfor high-order methods, are handled by operators with the summa-tion by parts property, the discrete counterpart of the integration byparts property. With these types of difference operators, it is possibleto prove discrete L2 estimates for the discrete solutions.

The non-dissipativity of the base scheme leads to two problems.First, the approximation is non-linearly unstable, and second,oscillations develop around the shocks. To overcome the first pro-blem, we precondition the equation by so called entropy splitting,and add a small high order artificial dissipation operator. Entropysplitting splits certain derivatives of non-linear functions into aconservative and a non-conservative part. This difference methodallows discrete L2 type estimates also for non-linear problems.Nevertheless the solution sometimes blows up (in a point) and artificialdissipation is required. The scheme becomes more stable, but it is notas accurate for long-time integrations. We are currently investigatinghow to adapt the entropy splitting together with artificial dissipation.The second difficulty with high-order methods, the oscillations aro-und discontinuities, is overcome by applying a dissipative filter ope-rator after each time step with a switch, which turns on only neardiscontinuities. We are currently studying new switches derived fromwavelet analysis of the flow field.

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In flame fronts and detonation waves, the combustion phenomenaare concentrated in a small part of the computational domain. Wetherefore use adaptive mesh refinement for such problems. Therefinements are made in rectangular patches with data interpolated tothe boundaries of the fine grid from the coarse grid. For higher-orderdifference approximation, high order interpolation formulas have tobe used. Analysis of the stability of such interpolation methodsproduced stable, interpolation formulas.

Fig.1 displays density contours of a viscous Riemann problemin a box. Initially the gas has two states at rest, separated by a wall atx=0.5. When the wall is removed, a shock wave moves right. Aboundary layer is developed at the lower wall, behind the shock wave.The reflected shock travels to the left and interacts with the boundarylayer, creating the complicated structure seen in Fig.1. A gridconverged solution was obtained with the new high order method.With standard TVD techniques, grid convergence was not possiblefor the resolutions allowed by our computing resources.

Fig. 2 shows simulation of a burning gas with one chemicalreaction. The gas is ignited with low energy so the flame speed isinitially low. Over time, a pressure wave builds up ahead of the flame,which compresses the gas and eventually ignites a detonation. Fig. 2shows density contours just before the detonation starts. Fig. 3 showsthe maximum pressure in the flow as function of time. Pressures upto 1000 times the initial pressure can develop through the transitionprocess. This problem is very stiff, and a real challenge for numericalmethods.

0.4 0.5 0.6 0.7 0.8 0.9 10

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Figure 2: Density andmass fraction contoursbefore DDT.

Figure 3: Pressure historyand shock-flame distance ofDDT.

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Algorithms for Multiphysics ModelsEver more complex mathematical models for scientific and technicalphenomena are created by refining existing ones and by couplingmodels for very different interacting physical phenomena. The notionof multiphysics was coined for the latter type of model. Themathematical description is a mixture of ordinary and partial diffe-rential equations, and algebraic equations: a system of partial diffe-rential-algebraic equations. The method of lines is an established ap-proach for handling the spatial variation. The model is discretized inspace first, leading to a large differential-algebraic equation system.For a number of standard models, it is well-known how to solve theresulting system efficiently. In case of partial differential-algebraicequations, new and unexpected numerical phenomena occur. Newtheoretical, algorithmic, and implementational developments areneeded.

Our goals are to find characterizations of general classes ofmultiphysics models, which can be successfully treated by the methodof lines, and to provide reliable and efficient numerical methods fortheir solution. The first steps have been taken in close cooperationwith groups at the Humboldt University of Berlin and the Universityof Lund and in collaboration with COMSOL AB Stockholm. Newefficient and robust codes for solving differential-algebraic equationsup to index 2 have been developed. [Hanke, 2001; Hanke and Lamour,2001]. They have been used in the PSCI project on porous mediaflow with surface reactions and will be included in future versions ofthe FEMLAB software product.

References[Efraimsson et al., 2001] Efraimsson, G., Nordström, J., and Kreiss,

G., Artificial Dissipation and Accuracy Downstream of SlightlyViscous Shocks, AIAA 2001-2608, (2001)

[Hanke, 2000] Hanke, M., Towards a new implementation of anonlinear solver for FEMLAB. Report TRITA-NA-0011, (2000)

[Hanke, 2001] Hanke, M., A new implementation of a BDF methodwithin the method of lines. Submitted. (2001)

[Hanke and Lamour, 2001] Hanke, M., and Lamour, R., Consistentinitialization for nonlinear index-2 differential-algebraicequations: Large sparse systems in Matlab. Submitted.(2001)

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[Kreiss et al., 1994] Kreiss, G., Lundbladh, A., and Henningson, D.,Bounds for threshold amplitudes in sub critical shear flows, J FluidMech, vol 270, (1994)

[Kreiss et al., 2001] Kreiss, G., Efraimsson, G., and Nordström, J.,Elimination of first order errors in shock calculations, SIAM JNum Anal, 38, no 6, (2001)

[Kreiss and Liefvendahl, 2001] Kreiss, G., and Liefvendahl, M.,Numerical investigation of examples of unstable viscous shockwaves, in Proceedings of HYP2000 in Magdeburg, accepted. (2001)

[Kreiss and Siklosi, 2001] Kreiss, G. and Siklosi, M., Provingexistence of nonlinear differential equations using numericalapproximations, Proceedings of HYP2000 in Magdeburg,accepted.(2001)

[Kupianen and Kreiss, 2001] Kupianen, M., and Kreiss, G., Stabilityinvestigation of a shock wave solution of the Euler equations,TRITA-NA-0124, (2001)

[Liefvendahl and Kreiss, 2001a] Liefvendahl, M., and Kreiss, G.,Stability of viscous shock waves for problems with non-symmetricviscosity matrices, SIAM J Math Anal, accepted. (2001a)

[Liefvendahl and Kreiss, 2001b] Liefvendahl, M., and Kreiss, G.,Analytical and numerical investigation of the resolvent for planeCouette flow, SIAM J Appl Math, submitted.(2001)

[Liefvendahl and Kreiss, 2001c] Liefvendahl, M., and Kreiss, G.,Bounds for the threshold amplitude for plane Couette flow, J Non-linear Math Phys, Submitted. (2001)

[Liefvendahl, 2001] Liefvendahl, M., A Chebyshev tau spectralmethod for the calculation of eigenvalues and pseudospectra,TRITA-NA-0125 (2001)

[Sjögreen and Yee, 2000] Sjögreen, B., and Yee, H. C., Wavelet BasedAdaptive Numerical Dissipation Control for Shock-TurbulenceComputation, RIACS Report, NASA Ames research center (2000).(to appear in J. Comput. Phys.)

[Sjögreen and Yee, 2001] Sjögreen, B., and Yee, H. C., GridConvergence of High Order Methods for Multiscal Complex Un-steady Viscous Compressible Flows, AIAA 2001-2599, Proceedingsof the 15th AIAA CFD Conference, June 11-14, 2001, Anaheim,CA. (to appear in J. Comput. Phys.)

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[Skogqvist, 2001] Skogqvist, P., High Order Adaptive DifferenceMethods for Combustible Flows, PhD Thesis, Stockholm Univer-sity, 2001.

[Skogqvist] Skogqvist, P., Stabiliby of High Order Mesh RefinementMethods (to appear in Math.Comp. )

[Yee and Sjögreen, 2001] Yee, H. C., and Sjögreen, B., DesigningAdaptive Low Dissipative High Order Schemes for Long-TimeIntegrations in “Turbulent Flow Computation”, D.Drikakis andB.Geurts (eds.) October 2001.

[Yee and Sjögreen, 2001] Yee, H. C., and Sjögreen, B., AdaptiveNumerical Dissipation/Filter Controls for High Order NumericalMethods in DNS/LES Progress and Challenges

Liu, Sakell, and Beutner (eds.), Greyden Press October 2001.

Adaptive Numerics forStochastic Differential EquationsAnders Szepessy, Kyoung-Sook Moon, Raul Tempone, GeorgiosZouraris

To provide useful and reliable measurements, a computation needsan estimate of its accuracy. The main question in numerical approxi-mation of differential equations is how the accuracy depends on thecomputational work. Higher accuracy needs more work. In adaptiveapproximation of differential equations, the number of degrees offreedom is minimized, to optimize the computational work, for a gi-ven error tolerance. Competitive computer programs for approxima-tion of ordinary differential equations have had adaptive time-stepcontrol for a number of years. Adaptive mesh control in commercialprograms for partial differential equations is becoming more com-mon. Our goal in this project is to develop reliable and efficientadaptive methods, with mathematical foundation, for problemsincluding stochastic features in material science, the geosciences, andmathematical finance.

Both the theoretical and the practical use of numerical methodsfor dynamic systems in combination with stochastic processes areless developed than numerical methods for deterministic problems.For example, one of our results seems to be the first on adaptive ap-proximation of expected values of solutions to stochastic differentialequations [Szepessy et al., 2001].

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Our most recent interest is to construct adaptive algorithms for whichwe can prove optimal convergence rates. We have such results forordinary and stochastic differential equations [Moon et al., 2001b;Moon et al., 2001a], which seem possible to generalize to partial dif-ferential equations. The analysis is based on a variational principleto derive error representations of the global error as a weighted sumof local errors. In the case of ordinary differential equations, we showthat this error representation is, in a sense, the only useful globalerror indicator for adaptive mesh refinements. The corresponding errorrepresentations for stochastic problems are richer, including optimaldeterministic and optimal stochastic refinements.

Figure 1. Trajectories and probability density function for the Euro-pean put-option example.

The figure illustrates an application: European put-option prices,which are determined by the price of the underlying stock. The pricedevelopment is modeled by the solution X(t) of an Ito stochastic dif-ferential equation, and the price is then g(X(T)). The adaptive algorithmshould compute the expected value of g(X(T)) accurately with mini-mal work. The x-t plane shows trajectories X(t) starting at (X

0,0) and

ending in (X(T),T). The function p(x) is the probability density functionof the random variable X(T).

p(x)g(x)

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References[Szepessy et al., 2001] Szepessy, A. Tempone, R. and Zouraris, G.,

Adaptive weak approximation of stochastic differential equations,Comm. Pure Appl. Math., 54, 1169-1214, 2001.

[Szepessy, 2000] Szepessy, A. High frequency asymptotics for 2Dviscous shocks, Indiana Univ. Math. J., vol. 49 (2000), no. 4., 1623-1673.

[Moon et al., 2001a] Moon, K.-S. Szepessy, A., Tempone, R. and Zouraris,G.E. Hyperbolic differential equations and adaptive numerics, Theory and numerics of differential equations, Eds. J.F. Blowey, J.P. Coleman and A.W. Craig Springer Verlag, New York, 2001.

[Moon et al., 2001b] Moon, K.-S. Szepessy, A. Tempone, R. andZouraris, G.E., Convergence rates for adaptive approximation ofdifferential equations based on global and local errors, preprint,2001.

[Björk et al., 2000] Björk, T. Szepessy, A. Tempone, R. Zouraris,G.E. Monte Carlo Euler approximation of HJM term structurefinancial models, preprint, 2000.

Computational ElectromagneticsBjörn Engquist, Bo Strand, Erik Abenius, Ulf Andersson, GunnarLedfelt, Lars Eriksson, Åke Rydell, Fredrik Bergholm, Stefan Hag-dahl, Anders Nilsson, Anders Ålund, Andreas Atle, Christer Johans-son, Lennart Hellström, Sandy Sefi, Jesper Oppelstrup, Aurora Lei,Lars Lovius, Per Öster

Electronic systems are increasing rapidly in number and complexityand they perform more and more safety critical functions in forexample aircraft and cars. Their sensitivity to electromagneticdisturbances also increases. Systems that rely on electromagnetic ra-diation for communication and detection also follow this trend. Timelydevelop-ment of new such products with assured quality requires goodelectromagnetic development tools. New simulation tools are neededfor fast and cost-efficient development of prototypes with the rightquality from the start, for trouble shooting, for verification, fordevelopment of test methods, and for research. The simulation

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environment must support a hybrid approach where different methods,as well as results from measurements, form building blocks that caneasily be combined differently for different applications and problems.

The Parallel and Scientific Computing Institute (PSCI) at KTHand Uppsala University has run the national project GeneralElectromagnetic Solvers (GEMS), and the research activities at theNA-group are closely coordinated with this industrial project. GEMSis a collaboration between PSCI, the Swedish Defense Establishment(FOI), Ericsson Microwave Systems, Saab Ericsson Space, and SaabAvionics. The project’s main objective is to develop a state-of-the-artgeneral electromagnetic software suite that meets present and futuredemands from Swedish industry in an international perspective. Theproject was funded by the National Program for Aeronautics Research(NFFP), NUTEK, and KTH over the period 1998-2000 with a smal-ler effort planned for 2000-2003.

GEMSThe two GEMS software packages are in turn hybrids of several codesand are based on methods at the research frontier. One code is basedon time-domain methods and the other on frequency-domain methods.For excitation of waveguides, a modal decomposition solver has beendeveloped. The codes are as general as possible and will allow simu-lation of complex systems for a wide frequency range. Among theapplications are antenna- and wave-guide analysis, studies in Electro-magnetic Compatibility (EMC), and scattering problems. The codedevelopment is supported by a research program, where new algo-rithms and potentially interesting fields are investigated.

The time-domain (TD) code is based on the classical Yee FDTDfinite difference method on a Cartesian staggered grid hybridized witha finite element method (FEM) and a finite volume (FV) method onunstructured grids. Figure 1 illustrates how the structured andunstructured grid types are fit together to combine the compu-tationalefficiency of Cartesian grids with an unstructured grid adapted to thecurved surfaces.

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Figure 1. A hybrid grid for the nose of the SAAB 2000 aircraft withan unstructured region embedded in a Cartesian grid.

The parallel and out-of-core FDTD code uses leap-frog time integra-tion, plane wave and wave-guide excitation, and Berenger's PML andUPML absorbing boundary conditions. The complexity of materialmodels ranges from perfect electric conductors to frequency-dispersivematerials. Sub-cell models for fine-scale objects such as thin wiresand thin sheets are included as well as near-to-far-zone transformationsfor calculation of radar cross sections. Multi-block decompositionand the use of fast disk storage allow large problems to run out-of-core with acceptable speed penalty. For multi-processor parallelism,the blocks are distributed among the parallel processors. Boundarydata are interchanged by message-passing libraries such as MPI. Astatic load balancing algorithm distributes the workload evenly amongthe processors. The unstructured solvers are integrated in the FDTD-code by a general mechanism for data exchange between the structuredand unstructured regions. Results from FDTD-FEM hybridcalculations are shown in Figure 2.

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Figure 2. An electromagnetic pulse illuminates an aircraft head onwith horizontal polarization. Surface currents calculated by theFDTD-FEM hybrid solver are shown when the main pulse reachesthe tail of the aircraft.

Frequency-domain methods are preferable in many situations.Boundary element methods, often referred to as the Method ofMoments (MoM), are usually chosen when

(i) the volume enclosing the problem is large, (ii) the area of the scattering objects is small,(iii) only one or a few frequencies are required.

The computational complexity of classical MoM is proportional tothe sixth power of the frequency. This severely limits the size ofproblems, and several methods of circumventing this limitation havebeen assessed in the CEM program. Efficient (Nedelec) boundaryelements are used together with parallel direct and iterative solvers.Because surfaces of very large structures tend to have large radii ofcurvature, the method of Physical Optics (PO) has been tested. Ray-based methods, in particular the Uniform Theory of Diffraction (UTD),were shown to exhibit good performance for even larger problems.Figure 3 illustrates how direct and reflected rays are traced. Dramatic

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improvements in performance have been demonstrated by employingthe so-called Fast Multilevel Multipole Method. Finally, hybridizationbetween MoM, PO, and UTD has been studied to facilitate the analy-sis of large, aggregated objects with various scale-lengths. Iterativemethods are used to couple between these methods.

Figure 3. A point source is situated above a generic satellite. The raytracer finds the shortest direct and reflected paths between the sourceand the observer points underneath the satellite. The direct andreflected fields computed by UTD are summed up at the observerpoints.

New ProjectsThe supporting research program mainly focuses on long-term topicsaimed at increasing the accuracy, performance, and functionality ofthe methods in the future. For the TD method, accuracy and stabilityfor the hybridization, sub-cell models, and parallelization techniquesare studied. Iterative methods for MoM – including Fast MultilevelMultipole Methods, fast ray tracing in UTD, and studies of differenthybridization techniques between MoM, PO and UTD – are activeresearch areas for the FD methods.

With the GEMS project completed in early 2001, the CEM re-search is re-focused in new and follow-up projects. GEMS2 aims atvalidating the GEMS codes on industrial applications and improvingtheir functionality and performance. Within the NFFP-project SMARTthe focus is on Radar Cross Section (RCS) applications; and in theproject Antenna Arrays, applications of the MoM-code for antennadesign are developed.

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References[Abenius et al., 2000a] Abenius, E., Andersson, U., Edelvik, F.,

Eriksson, L., and Ledfelt, G., Hybrid time domain solvers for theMaxwell equations in 2D. Technical Report 2000:01, PSCI, Paralleland Scientific Computing Institute, KTH, SE-100 44 Stockholm,Sweden, February 2000.

[Abenius et al., 2000b] Abenius, E., Strand, B., and Alestra, S.,Inverse electromagnetic scattering using the finite-difference time-domain (FD-TD) method. In AP2000 Millennium Conference onAntennas & Propagation, Davos, Switzerland, 2000.

[Abenius et al., 2001] Abenius, E., Andersson, U., Edelvik, F.,Eriksson, L., and Ledfelt, G., Hybrid time domain solvers for theMaxwell equations in 2D. Int J Num Meth in Engrg, 2001. Acceptedfor publication.

[Andersson, 2001] Andersson, U., Time-Domain Methods for theMaxwell Equations. PhD thesis, KTH, February 2001.

[Bergholm., 2000] Bergholm, F., Hagdahl, S., and Sefi, S., A modularapproach to GTD in the context of solving large hybrid problems.In AP2000 Millennium Conference on Antennas & Propagation,Davos, Switzerland, 2000.

[Bruel, 2000] Bruel, M., Dielectrics. Technical report, Nada, KTH,2000.

[Edelvik and Ledfelt, 2000] Edelvik, F., and Ledfelt, G., Explicithybrid time domain solver for the Maxwell equations in 3D, J. Sci.Comput., 15(1), 2000.

[Edelvik and Ledfelt, 2001] Edelvik, F., and Ledfelt, G., A comparisonof FD-FV and FD-FE hybrid solvers in the time-domain. In FourthInternational Workshop on Computational Electromagnetics in theTime Domain: TLM/FDTD and Related Techniques, volume 1,pages 179-184, Nottingham, UK, September 2001.

[Edelvik and Strand, 2000] Edelvik, F., and Strand, B., Frequencydispersive materials for 3D hybrid solvers in time domain. In An-tenn00, Nordic Antenna Symposium, Lund, Sweden, pages 63-68, September 2000.

[Edelvik and Strand, 2001] Edelvik, F., and Strand, B., Frequencydispersive materials for 3D hybrid solvers in time domain. IEEETransactions on Antennas and Propagation, 2001. to appear.

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[Edelvik et al., 2000] Edelvik, F., Andersson, U., and Ledfelt, G.,Hybrid finite volume - finite difference solver for the Maxwellequations. In AP2000 Millennium Conference on Antennas &Propagation, Davos, Switzerland, 2000.

[Edlund et al., 2000] Edlund, J., Hagdahl, S., and Strand, B., Aninvestigation of hybrid techniques for scattering problems ondisjunct geometries. In AP2000 Millennium Conference onAntennas & Propagation, Davos, Switzerland, 2000.

[Jacques, 2000] Jacques, A-C., Ray diffraction. Technical report, Nada,KTH, 2000.

[Ledfelt et al., 2000] Ledfelt, G., Edelvik, F., and Andersson, U.,Hybrid time domain solvers for the 3D Maxwell equations. In An-tenn00, Nordic Antenna Symposium, Lund, Sweden, pages 57-62, September 2000.

[Ledfelt, 2001a] Ledfelt, G., Arbitrarily oriented thin wires for theFD-TD method. In Fourth International Workshop onComputational Electromagnetics in the Time Domain: TLM/FDTDand Related Techniques, volume 1, pages 195-200, Nottingham,UK, September 2001.

[Ledfelt, 2001b] Ledfelt, G., Hybrid Time-Domain Methods and WireModels for Computational Electromagnetics. PhD thesis, KTH,March 2001.

[Sefi, 2000] Sefi, S., Design and architecture of MIRA, a ray-basedelectromagnetic code., Master's thesis, Universite Joseph Fourier,Grenoble, France, October 2000.

[Strand et al., 2000] Strand, B., Andersson, U., Edelvik, F., Edlund,J., Eriksson, L., Hagdahl, S., and Ledfelt, G., GEMS - a Swedishelectromagnetic suite of hybrid solvers - technical aspects. InAP2000 Millennium Conference on Antennas & Propagation,Davos, Switzerland, 2000.

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Multi-Phase FlowsBjörn Engquist, Reynir Gudmundsson, Katarina Gustavsson, Heinz-Otto Kreiss, Jesper Oppelstrup, Anna-Karin Tornberg, JacobYström

The simultaneous motion of two or more phases – gas, liquid, orsolid – is probably the most common type of flow in natural andengineering processes. Boiling liquids, silt-laden rivers, oil recoveryby injection, granular media movements, and blood flow are obviousexamples. With growing computer power, it is becoming possible tostudy the basic microscopic models in enough detail and realism tosupport development of simulation models for macroscopic modelscapable of quantitative predictions for realistic applications.

The spectrum of models is wide, and the mathematics andnumerical methods are in rapid development. The research at NADAfocuses on models for separated flows and two-fluid continuummodels for dispersed flows. An exciting challenge is to develop meth-ods for the particle models that will allow extraction of constitutiverelations for the continuum (two-fluid) models. For the general two-fluid continuum model, the emphasis is on developing efficientnumerical methods based on mathematical analysis. A particular modelfor de-watering of flocculated suspensions under development since1994 is being extended to take structural properties of the solid phaseinto account.

Separated and Dispersed FlowsFollowing each particle in the dispersed phase makes it possible tomodel particle-fluid and particle-particle interactions from firstprinciples. However, computer resources limit the number of particlesto the point where large-scale behavior is difficult to extract.

The continuum models are formulated for averages (over time,space, and ensemble) and require closures for macroscopic quantities,for example for how stresses relate to strains and strain rates. Suchconstitutive relations are empirical and must be obtained from expe-riment or particle simulations.

In a separated flow model, the representation of the interfacebetween the phases is one of the important features of an efficientand accurate simulator. We have developed the Segment ProjectionMethod [Tornberg, 2000] as a variant of the Level Set Method[Sethian, 1988]. The separated flow model is applied to particle

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suspensions by using a sizeable viscosity contrast. Early experimentsshow promise in predicting average concentrations. More reliablepredictions require many more particles, and a parallelizable algorithmis now under development.

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De-Watering of Flocculated SuspensionsIt has been shown that certain aspects of the micro-structure of thesuspension must be modeled in order for the continuum model tomimic behavior seen in experiments. A two-scale model is now un-der study. It represents floc properties such as size, solid fraction,yield stresses, plastic flow rule, etc., thus providing greater approxi-mation power. However, the increased complexity also requires newconstitutive models and more detailed experimental data for propervalidation. As an example, we show a plausible effect of floc

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compression and break-up on permeability. In compression, flocs aretightly packed into a homogeneous medium whose solids fractiongrows; in subsequent dilation, the medium breaks up into larger pieces.The resulting permeability is much higher than for a homogeneousmedium of the same bulk concentration:

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Concentration contours using two different permeability models. InFigure 4a, to the left, the permeability is a reversible function of thevolume fraction.Figure 4b, to the right. The permeability function takes into accountmicro structure. Note the higher concentration.

Numerical Methods for Two-Phase Flow EquationsThe Cauchy problem for the standard Eulerian two-fluid formulationsof dispersed two-phase flow is locally in time well-posed. However,it suffers specific high wave number instability: it is of mixedhyperbolic-parabolic type and in certain physically reasonable regionsof phase space the inviscid problem is non-hyperbolic.

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From numerical experiments with this model in 1D, we concludethat these instabilities result in the formation of weak solutions thatcannot be regularized in standard ways by second-order artificialdissipation because there is no vanishing dissipation limit. Experi-ments confirm that solutions to such regularized problem are stronglydependent on the size of the artificial dissipation. We currently searchfor other, new consistent interpretations, such as low-pass filtering inspace and time, of the solutions to the regularized problems. The figureshows particle concentrations of regularized two-phase flow, a solidparticle phase settling in incompressible fluid under gravity.

Figure 5. Volume solids fraction, iron particles settling under gravityin a water column. The computed solutions only differ in the artificialdissipation: 0.002 (top), 0.001(middle), and 0.0005 (bottom), 500 gridpoints.

References[Gustavsson and Oppelstrup, 2000], Gustavsson, K., and Oppelstrup,

J., Consolidation of Concentrated Suspensions – NumericalSimulations using a Two-Phase Fluid Model, Computing andVisualization in Science 3 (2000), 39-45.

[Gustavsson and Oppelstrup, 2001a] Gustavsson, K., and Oppelstrup,

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J., Numerical 2D Models of Consolidation of Dense FlocculatedSuspensions, Journal of Engineering Mathematics 41(2001), 189-201.

[Gustavsson and Oppelstrup, 2001b] Gustavsson, K., and Oppelstrup,J., Consolidation of Concentrated Suspensions – Shear andIrreversible Floc Structure Rearrangements, Computing andVisualization in Science 4(2001), 61-66.

[Kreiss and Yström, 2001] Kreiss, H.-O., Yström, J., Parabolicproblems that are ill-posed in the zero dissipation limit, acceptedfor publication, in Mathematical and Computer Modeling.

[Osher and Sethian, 1988] Osher, S., and Sethian, J.A., FrontsPropagating with Curvature Dependent Speed: Algorithms Basedon Hamilton-Jacobi Formulations, J. Comp. Phys., 79, 12-49(1988).

[Tornberg, 2001] Tornberg, A-K., PhD Thesis, Interface TrackingMethods with Application to Multiphase Flows. TRITA-NA-0010.

[Yström 2001] Yström, J., On two-fluid equations for dispersedincompressible two-phase flows, accepted for publication inComputing and Visualization in Science.

Computational Harmonic AnalysisJan-Olov Strömberg

The wavelet theory has been developed during the last decades,branching out from harmonic analysis and merging with signal analy-sis. The importance of this field has grown rapidly, and manyapplications have been found, both in signal processing and innumerical analysis.

To stimulate the application of these new mathematical methods,the Swedish Strategic Research Foundation through the NationalNetwork in Applied Mathematics (NTM) decided to fund a chair inComputational Harmonic Analysis at KTH. The new professor wasinstalled in 1998 in a joint position with NADA and the Departmentof Mathematics.

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Image Processing and Data Compression(with Yale University)Fast wavelet processing and coding techniques have been developedfor image and data compression in collaboration with Yale Univer-sity Departments of Mathematics and Computer Science. Image ma-nipulation techniques using wavelet algorithms – for instance de-noising, sharpening (deconvolution), and image enhancement – areunder development. The algorithms are being built into software forcompression of seismic data in collaboration with the American com-pany Geo Energy.

VIDCOD: Video CompressionIn collaboration with professor Amir Averbuch, Tel Aviv University,and InoWrap Corporation we are starting a project in video codingfor wireless communication. This is a pre-project under the EU SixthFramework program.

Numerical AnalysisSingular integral operators are used for solving PDE with boundaryconditions. One visiting Ph.D. student supported by NFR (NorsktForskningsråd) is involved in this project. We are studying alternativeways of representing and compressing these operators with wavelets.

Wavelets in Medical Image and Signal Processing(with Professor Tom Brismar, Dept. Neurophysiology, Karolinska In-s t i tu te t )The basic problem is to detect transients in a collection of parallelsignals from EEG measurements in order to localize defect brainactivities. One Ph.D. student is involved in the project.

We are also starting a project in collaboration with Dept. ofHearing and Communication, KI, about confocal problems in 3Dimaging. The iterative statistical methods in common use can bestabilized by wavelet de-noising techniques. The image manipula-ting methods mentioned above are also being considered for this pro-blem.

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Wavelets in Vibration AnalysisThe collaboration with Nåiden Teknik, Luleå, the Mathematics Cen-ter, Luleå University of Technology, and several paper mills, issupported by NTM. Nåiden is a small company (recently bought upby SKF) that provides measuring equipment for monitoring paper-manufacturing machines. The continuous wavelet transform is usedto get a time frequency analysis of vibration signals from bearings inorder to predict maintenance requirements and potential failures ofdefective bearings. A feature extraction algorithm based on the BestLocal Discriminant Basis of Wavelet Packet functions is used forpattern recognition.

Figure 1. Time-frequency analysis of vibration signals from a defectivebearing. Using this analysis we consider several algorithms forautomatic detection of defective bearings.

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0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50

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Figrure 2. Plot of the first two selected extracted feature coordinatesfrom a test set of signals from bearing vibrations. The markingindicates defective outer ring (red squares), defective inner ring(yellow stars), nominal (green circles).

References[Meyer et al., 2000] Meyer, F. G. Averbuch, A. Z.and Strömberg,

J.-O. Fast Adaptive Wavelet Packet Image Compression. IEEETransaction on Image Processing May 2000, Vol 9Number 5 [p.792 - 800].

[Ericsson et al] Ericsson, S. Grip, N., Johansson, E. Persson, L.-E.Sjöberg, R., and Strömberg, J.-O. Automatic Detection of LocalBearing Defects in Rotating Machines,Part I. (Final Report froma project in Luleå).

Computational Physics

Global Optimization andthe Energy Landscapes of Dzugutov ClustersSergei Simdyankin, Mikhail Dzugutov, J. Doye, David Wales

Much computational work on supercooled liquids and glasses hasfocused on the behavior exhibited by systems interacting accordingto simple model potentials. An attractive approach is to use a singlecomponent system with a potential that is designed to prevent cryst-

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allization. We have employed the potential originally suggested byDzugutov, which has a local maximum at approximately 1.4 timesthe equilibrium pair distance in order to disfavor close-packed struc-tures.

Our aim has been to further understand the structural impli-cations of the Dzugutov potential by identifying the characteristicstructural motifs associated with the global minima of Dzugutovclusters. Furthermore, we have examined the consequences of thepotential for the topography of the energy landscape of these clusters.As well as the insights into bulk behavior that these results provide,they will also be potentially helpful in understanding the structuresof clusters that favor polytetrahedral structure.

Our results show that the global minima of Dzugutov clustershave non-compact polytetrahedral structures, and some examples areillustrated in Figure 1. The interior atoms in these clusters almostalways have an icosahedral coordination shell, rather than otherpolytetrahedral coordination shells that involve disclination lines,because the latter involve too large a strain energy. The 13-atomicosahedral units that make up the global minima are usuallyinterpenetrating or face-sharing, and both these motifs are commonlyobserved in metallic crystals that have icosahedral coordination. Asthe size of the clusters increases, the arrangements of the icosahedralunits change from one-dimensional chains to two-dimensional ringsto three-dimensional porous networks. These results are consistentwith the previous observation that the bulk liquid can sustain a distri-bution of free volume in the form of atomic size vacancies.

Dzugutov clusters typically have rough multiple-funnel energylandscapes. These features make global optimization difficult withimplications for the dynamics of supercooled Dzugutov liquids. Theirextended icosahedral domains, similar to the structures that we findfor the clusters, grow as the temperature is decreased. Furthermore,our results help to explain why the bulk phase diagram appears not toinclude a stable liquid, and suggest the possibility of phases withcomplex low-density network structures.

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Figure 1. Some Dzugutov clusters representing global energy minima.The labels indicate the number of atoms in each cluster

References[Doyle et al., 2001] Doye, J.P.K., Wales, D.J., and Simdyankin

S.I. Global Optimization and the Energy Landscapes of Dzugu-tov Clusters FARADAY DISCUSS. vol. 118, 159-170 (2001)

Fast and Stable Algorithms for Fracture MechanicsJohan Helsing

The fracture mechanics community needs methods for accurateprediction of stress fields in loaded elastic materials with a largenumber of cracks and inclusions. Accurate solutions are a necessityfor safety-critical applications.

The understanding of the evolution of crack-patterns, even onthin films, is qualitative, at best. Of interest are complicated situations,including fatigue simulations where a sequence of loading blocks isapplied.

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Engineers working with design of composite materials need to modelthe evolution and link up of matrix micro-cracking and fiber-matrixdebonding, which eventually may lead to macroscopic fracture.The project goal is to develop software for the simulation of micro-crack evolution in inhomogeneous materials. The software ischaracterized by the three following features. 1) It is stable. The resultconverges as the mesh is refined. The accuracy can be controlled. 2)It is fast. Linear complexity in terms of discretization points isachieved. Large systems can be modeled. 3) It is flexible. Differentcrack-growth criteria, loads, non-linearities, and a wide array ofconfigurations and crack patterns are allowed.

These features are essential to verify theories against experi-ments, and as a tool for optimization of composite material systems.So far as we are aware, there is no such software that performs to fullsatisfaction, and the development described here represents a majorstep forward. Our codes are used at University of Utah, Luleå Uni-versity, and Narvik Institute of Technology [Byström et al., 2001],and they are now sufficiently flexible to replace many pages of thehandbooks currently used for crack-resistant designs.

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Figure 1. Left, convergence of a quantity qref, related to stress, on amultiply-connected domain for three different Fredholm equations.DP refers to double precision calculations. QP refers to quadrupleprecision. Right, convergence of effective elastic moduli for a setupwith closely spaced ellipses. Stars and open circles refer to differentschemes for evaluation of layer potentials close to their sources. Themeshes are uniformly refined.

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A Three-Pronged AttackThe algorithmic development of integral equation methods advancesalong three frontiers.

One effort is to find efficient integral equations. We have deri-ved, implemented, and tested integral equations for several basictopologies, which may occur in the context of crack propagation [Hel-sing, 2000a; Helsing and Jonsson, 2001b; Helsing and Jonsson,2001d]. Convergence studies typically look like the left image ofFigure 1.

A second effort is to verify that accuracy control and linearcomplexity can also be achieved for realistic problem sizes. We havedone computations involving thousands of inclusions, overlappingobjects, and cracks [Helsing and Jonsson, 2001e], and also a largetortuous single crack [Englund, 2001]. See the right image of Figure1 for a typical convergence study.

A third effort is to look at more general problems to broadenthe applicability of our methods. The results include a stable solverfor a class of non-linear contact-problems [Helsing and Peters, 2000],solution of a 3D crack-problem [Helsing et al., 2001], and discretedislocation dynamics for plasticity [Jonsson, 2001].

Recent Theoretical AdvancesIntegral equation techniques, in general, are not a panacea. But if agiven problem can be formulated as a Fredholm integral equation ofthe second kind, there is something to gain. Therefore, we put a largeeffort into finding such equations, which are of the type

(I+C)w(r)=f(r) (1)

where I is the identity, C is a compact operator, w(r) is the unknownfunction that we solve for, and f(r) is a known right-hand side.

A problem can often be formulated in several ways as anequation of the type (1). When C, in addition to being compact, isalso non-singular, and w(r) is the limit of an analytic function, a verybeneficial situation occurs. Then high-order quadrature is effective,also on polygonal domains [Helsing and Jonsson, 2001a], and rapidlyconverging numerical solutions can be constructed. It has beenregarded as a formidable problem to find such Muskhelishvili-typeequations. Nevertheless, we recently discovered a Muskhelishvili-

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type equation for the 2D stress problem on multiply-connecteddomains [Helsing and Jonsson, 2001e]. Using the same potentialrepresentations as for inclusions and cracks, it allows unifying thepotential representations, retiring classic equations in the process, andobtaining faster converging results. The results, Figure 1, left image,are computed with this new equation for a setup with smoothboundaries.

For zig-zag shaped body-cracks, C must be a composition of asingular operator and a compact operator. We have found efficientcorner quadratures for the compact part of this operator [Helsing andJonsson, 2001b]. Using the theory for the solution of the Rie-mann-Hilbert problem, we have also outlined how to find efficient cornerquadratures for the singular part of the operator [Englund, 2001].

References[Helsing, 2000a] Helsing, J., On the interior stress problem

for elastic bodies, ASME J. Appl. Mech. 67 658-662.[Helsing and Peters, 2000] Helsing, J. and Peters, G. (2000) An

efficient numerical algorithm for cracks partly in frictionlesscontact, SIAM J. Appl. Math. 61 551-566.

[Helsing, 2000b] Helsing, J. (2000). Corner singularities for ellipticproblems: special basis functions versus “brute force”, Comm.Num. Meth. Engn 16, 37-46.

[Helsing et al., 2001] Helsing, J., Jonsson, A., and Peters G. (2001). Technical note: Evaluation of stress intensity factors for a square crack in 3D, Engn Fracture Mech. 68 605-612.

[Byström et al., 2001] Byström, J., Helsing, J., and Meidell, A. (2001)Some computational aspects of iterated structures, Composites PartB. 32, 485-490.

[Helsing and Jonsson, 2001a] Helsing, J., and Jonsson, A. (2001)Complex variable boundary integral equations for perforatedinfinite planes, Engng Anal. Boundary Elem. 25, 191-202.

[Helsing and Jonsson, 2001b] Helsing, J. and Jonsson, A. (2001) Onthe computation of stress fields on polygonal domains with V-notches, Int. J. Num. Meth. Engn (in the press).

[Helsing and Jonsson, 2001c] Helsing, J. and Jonsson, A. (2001) Onthe accuracy of benchmark tables and graphical results in theapplied mechanics literature, ASME J. Appl. Mech (in the press).

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[Helsing and Jonsson, 2001d] Helsing J. and Jonsson, A. (2001) Aseventh order accurate and stable algorithm for the computationof stress inside cracked rectangular domains, (preprint).

[Helsing and Jonsson, 2001e] Helsing, J. and Jonsson, A. (2001) Stress calculations on multiply connected domains, (preprint).

[Englund, 2001] Englund, J. (2001) Fast, accurate and stable algorithm for the stress field around a zig-zag-shaped crack,(preprint).

[Jonsson, 2001] Jonsson, A. (2001) Discrete dislocation dynamics by an O(N) algorithm, (preprint).

Large-Scale Computational AerodynamicsArthur Rizzi, Björn Sjögreen, Marco Kupiainen, Joakim Möller, Chris-tian Wauquiez, Anders Ytterström

The program covers applications and algorithmic development incomputational aerodynamics and is coordinated with the research atthe Department of Aeronautics, KTH, and supported by PSCI. Manyflows – such as jets, phenomena relating to air intake dynamics, andhigh-angle of attack flows around wings – are unsteady and requireorders of magnitude larger computing resources than do steady flows.Parallel computing is an enabling technology for moving forward inthis field.

The thesis by Ytterström in 2001 studies dynamic load balancingfor unsteady and steady CFD on parallel computers. The study usesan industrial-standard CFD-solver, NSMB [Vos et al., 1998], coupledto a pre-processing tool, MB-Split, for load balancing for distributedand shared-memory machines. To be effective, the load balancer takesactual timings from the processors used, because the computationsmay change with time for unsteady flows. Predicting the performanceof a proposed division of labor between processors is very difficultand may depend on such factors as non-obvious details of problemsizes relating to processor cache size. Tests show that the dynamicapproach gives a much better result than using static performancemodels.

Airfoil shape optimization by CFD requires derivatives of theaerodynamic forces lift, moment, and drag with respect to designvariables. To compute these derivatives, we have investigatedautomatic differentiation, which is now supported by the MATLAB

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programming environment. An experimental code for low-speed tur-bulent flow simulation using potential flow coupled to integral lami-nar and turbulent boundary layer models was developed to test variousapproaches to derivative computation. A FreeWare version of thiscode, called Pablo, can be downloaded at <www.nada.kth.se/~chris>.First-order derivatives obtained by differences, forward, and reversemode were used in a number of optimization exercises applied to theNACA 4 digits library. Results are presented in [Wauquiez, 2000].

Slow convergence to steady-state solutions is a common pro-blem for CFD. If the solution procedure can be formulated as a fixedpoint iteration, such as time-stepping, a potential way to acceleratethe convergence is to apply the Recursive Projection Method (RPM),proposed for bifurcation analyses by Shroff and Keller in 1993.

RPM identifies an invariant subspace associated with the do-minant eigenvalues of the linearized problem. If the dimension ofthe subspace is small, by applying a Newton iteration to the part wherethe fixed-point scheme has poor convergence properties, a substantialincrease in the convergence rate can be obtained. Projections arecomputed from the Krylov spaces generated by the iterations to splitthe solution space; proper scaling of variables is advantageous forefficient identification of the subspace. The compressible flow-solverNSMB 4.5 was linked to a MATLAB implementation of RPM via aMEX-interface. RPM acceleration was tested with good success ontwo different flow cases, a supersonic nozzle and a subsonic airfoil.For each case, Euler, laminar, and turbulent computations were per-formed with more than threefold increases in convergence rates[Möller, 2001].

Simulation of jets by the Reynolds Averaged Navier Stokes(RANS) equations is difficult at best and requires tuning of turbulencemodels at least. Large Eddy Simulation resolves flow scales in theunsteady flow down to the mesh-size and models the effect of sub-grid scales by a spatial filter. While computationally much moredemanding than RANS, it is still manageable compared to models,which resolve all flow scales.

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One of the more recently started projects at NADA is LESinvestigation of jets. Project partners are Saab Bofors Dynamics AB,FOI, and KTH.

At the moment, reactive and non-reactive incom-pressible flowsare investigated. In the non-reactive simulations, a passive scalar,symbolizing the concentration of a fuel, is modeled with an extratransport equation to give information of, for example, mixingproperties of the flow. One- and two-step reaction rate modelsdescribed by Arrhenius laws give up to 10 equations per grid pointwhich must be solved every time-step on an 800K-point grid. Theflow solver used is a research version of the code FOAM (Field Ope-ration And Manipulation) developed at Imperial College and FOI.

The final goal is to investigate full hypersonic combustible 3Dflows. In order to perform these simulations, FOAM will be ported tothe IBM SP2 at PDC.

Figure 2: An illustration of theenhanced convergence rateobtained by using RPM on a 2Dsupersonic nozzle computation.

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Figure 3: Time accuratesimulation of a reactive jet. Thefigure shows an iso-surface of thevorticity magnitude at T=0.01s.Re=5500, 800000 grid points.Note the the smoke ring presentin the top figure.

Figure 4: T=0.05s, Re=5500,800000 grid points. The smoothiso-surface is broken up by vortexstretching resulting in a transportof energy to the fine scales, whichwill eventually dissipate intoheat.

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References[Möller, 2001] Möller, J., Studies of Recursive projection Methods

for Convergence acceleration of Steady State Calculations.,Licentiate Thesis, TRITA-NA-0119, Royal Institute of Technology,Stockholm, Sweden, June 2001.

[Vos et al., 1998] Vos, J.B., Leyland P., Lindberg P.A. , Kemenade,V. van., Gacherieu, C., Duquesne, N., Lotstedt, P., Weber, C.,Ytterström, A., NSMB Handbook 4.0, Dept. of AeronauticsKTH, 1998

[Wauquiez, 2000] Wauquiez, Ch., Shape Optimization of Low SpeedAirfoils using MATLAB and Automatic Differentiation, Lic.Thesis, Report TRITA-NA-0004, Jan. 2000, Royal Institute ofTechnology, Stockholm, Sweden.

[Ytterström, 2001] Ytterström, A., Parallel Computing for Applications in Aeronautical CFD, Doctorial Thesis, Report 2001-15, Royal Institute of Technology, Stockholm, Sweden, June 2001.

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Centres at NADA

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Henrik I. Christensen

The Centre for Autonomous Systems is an interdisciplinary researchcenter that does research on advanced robotic systems. It is composedof four research groups from mechatronics, electrical engineering,computer science, and applied mathematics. An integral part of theactivities is a graduate school with about 25 Ph.D. students from thedepartments.

The overall themes for the research are systems integration andfully operational systems for realistic applications. To accomplishsuch systems, there is a need for efforts related to mapping and navi-gation, vision for localization and manipulation, advanced controlsystems, software architectures, and human-robot interaction. In ad-dition to topical research, the various efforts are integrated through anumber of integration demonstrators related to “service robotics” and“walking robots.” Finally, a number of spin-off projects are carriedout in collaboration with local industry.

For mobile robots to carry out missions in unknown or partiallyknown environments, it is necessary to equip them with facilities forautomatic mapping and localization using sensory input. To accommo-date such functionality research on sonar-based mapping andlocalization is carried out [Wijk and Christensen, 2000a] [Wijk andChristensen, 2000b]. This involves both localization in a prior knownenvironment and simultaneous localization and mapping [Jensfelt etal, 2000a] [Jensfelt et al., 2000b]. Ultrasonic sonars have limited range,precision, and speed, which limits their utility in large-scale environ-ments. Consequently the use of laser range sensors has gainedsignificant popularity over the last few years as the price of suchsensors has become reasonable. Studies using such sensors [Austinand Jensfelt, 2000] [Seiz et al., 2000] have demonstrated that it ispossible to build robust navigation and mapping systems for extendednavigation in in-door (structured) environments. Through fusion ofsonar and laser sensors, it is possible to provide systems solutionsthat guarantee localization with an accuracy better than 5 cm in a richvariety of environments. Consequently navigation in structured in-door settings has matured to a level that allows use in a wide varietyof applications.

Centre for Autonomous Systems, CAS

The Centre for AutonomousSystems is an interdisci-plinary research center thatdoes research on advancedrobotic systems.

www.cas.kth.se

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The location of the robot can be estimated through the use of externalsensors, but in many situations it is advantageous to complement thiswith methods that exploit proprioception and global sensors forestimation of the pose (position and orientation) of a platform. Tothis end research is carried out on the efficient use of a combinationof inertial and inclinometers for pose estimation [Rehbinder and Hu2000a] [Rehbinder 2000b]. Through efficient state- dependent fusionof sensory information, it is possible to provide bounded estimates ofthe robot state, which simplifies navigation tremendously [Matveevet al., 2000].

One of the most versatile sensors for estimation of the externalstate of the world is computational vision. For tasks such as manipu-lation, vision is indispensable. At the same time, the richness of visualinput poses a problem as it challenges robustness due to the difficultiesinvolved in interpretation of the visual data. It is well known that nosingle cue is robust to variation across position and illumination. Therobustness can in part be achieved through fusion of multiple diffe-rent cues and through use of prior models. For manipulation of objectsin the environment, research is carried out on real-time fusion ofrelatively inexpensive cues through the use of voting based methodsthat exploit a minimum of prior information [Kragic-Christensen2000a] [Kragic-Christensen 2000b] [Kragic-Christensen 2000c][Christensen-Eklundh 2000]. Through the use of model-based infor-mation, it is also possible to use similar methods for efficient naviga-tion in indoor settings [Ebert et al., 2000]. In addition, the use ofvision for accurate localization with respect to objects using plane-plane mapping has also been pursued as a precursor for grasping.Recently the center has acquired a state-of-the-art Barrett hand foractive research on manipulation and grasping [Strandberg et al., 2000].

Integration of robots systems involves a need for integration ofa range of different control methods into a unified framework fortask coordination and switching. To achieve continuity in motionacross tasks and actuators, there is a need for a unified mathematicalframework. The concept of hybrid dynamic systems provides such aunified basis for describing systems that includes both continuousand discrete state variations. The area of hybrid dynamic systems isrelatively new, and basic research is thus needed to enable formulationof a holistic framework for system control. Such basic research hasbeen carried out in a fruitful collaboration with UC Berkeley [Egerstedt

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et al., 2000] [Johansson, 2000]m[Johansson et al., 200] [Zhang etal., 2000]. Construction of advanced robot systems involves integra-tion of a rich variety of components into an operational framework.This typically involves integration of a large number of softwaremethods into a real-time system that enables robust operation.Accomplishing this active research involves design of flexibledistributed architectures that facilitate modular design, efficient run-time performance, and easy debugging. The research here involves ageneric robot architecture for distributed systems, where the interactionacross modules is described using a process algebra that allowsverification of system properties [Petersson et al., 2000a]. The inte-gration of a complete system can be achieved through the use of object-oriented models for the different modules in a systems, whichsimplifies design and allows for the use of modern pattern-orientedsoftware engineering methods [Lindström et al., 2000]. In a hard real-time setting it is often necessary to provide efficient models to enablethe design of systems with guaranteed performance. This calls forintegration of mechanical, control and software engineering methodsinto a unified framework for system analysis [Törngren and Redell,2000].

Large-scale adoption of robots for everyday use requires userinterfaces that allow easy interaction with the system for tasks suchas instruction and feedback. To this end it is essential to consider howa range of different modalities-such as gestures, speech, and graphics-can be combined into a unified framework for interaction. It is ofinterest to interpret the users’ activities to understand activities in theenvironment. For example, these can be achieved through 3Destimation of the motion of humans in the proximity of the robot[Sidenbladh et al., 2000a] [Sidenbladh et al., 2000b]. The actual fu-sion of gestures and speech is crucial to the design of efficient userinterfaces, which in addition also requires evaluation in the contextof regular users [Christensen et al., 2000].

To demonstrate the utility of the different research problems inreal-world applications, the center has defined two thematic modelsthat integrate research into operational systems that operate in realisticenvironments. The two models are: The Intelligent Service Robot, amobile platform for service type applications in a domestic setting;and Walking Robot Platform, a walking robot for operation inunstructured settings, such as forests.

Construction of advancedrobot systems involves inte-gration of a rich variety ofcomponents into anoperational framework.

...The Intelligent ServiceRobot,...and Walking RobotPlatform,...

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The service robot application is aimed at fetch-and-carry operationsin a building. Typical tasks could include cleaning, distribution ofmail in an office, and mobility support to the elderly in their houses.To achieve these tasks it is necessary to integrate methods for mapping,localization, manipulation, and control using a common softwareframework. Today the system has facilities for navigation overextended periods of time. In addition, a speech interface can be usedto instruct the system to carry out specific tasks. Typical tasks involvemail delivery and acting as a tour guide for laboratory visitors [An-derson et al., 1999]. Recently the system has been extended withfacilities for manipulation to allow handling of doors and picking upa limited set of objects [Petersson et al., 2000a].

The other model is a quadraped walking robot that has beendesigned to allow operation in a forest. The research has involvedthe mechanical design of the platform [Ridderström et al., 2000].This has involved the overall mechanical design, selection of actuatorsystem, the associated control electronics, and necessary compu-tational resources to allow control of the system. In addition the re-search has involved both basic design for locomotion [Hardarsson-Wikander 2000] and coordination of motion to achieve a variety ofgait patterns. The design and construction of a fully operationalwalking platform is a momentous undertaking. Currently, the sys-tem has facilities for basic walking, balancing and locomotion underjoystick control. Future work will be related to integration of higher-level control to achieve full autonomy.

In addition to the construction of systems to achieve operationalresearch prototypes, a number of applied projects are being carriedout in cooperation with industry. The work on navigation has matu-red to a level where it can be applied in commercial applications. Anexample of this is the use of these methods for automatic traversal ofswimming pools. All commercial pools have to be cleaned 100 % ona daily basis. Today this is achieved through manual sweeping of thepool with an underwater vacuum cleaner. By retrofitting a mechanicalcleaner, it is possible to build a system that can be used for automaticcleaning of pools. This project [Simoncelli et al, 2000] is carried outin collaboration with WEDA cleaners. Navigation techniques can alsobe used in domestic cleaning. Navigation techniques that have beendeveloped are being tested in collaboration with Electrolux forautomatic vacuum cleaning in domestic settings. Mobile robots are

...a number of appliedprojects are being carried outin cooperation with industry.

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obviously of tremendous potential for logistic systems in factoriesand enterprises. Consequently an exploratory project with ABB hasinvestigated the use of mobile platforms as part of industrial ITsystems.

The center for autonomous systems is the largest academic facil-ity that does research on robotics in Scandinavia. Consequently thecenter is involved in a significant number of international activities.Recently CAS became the coordinator of the European Robotics Re-search Network (EURON), which provides an infrastructure for robo-tics activities in Europe. The network is sponsored as a network ofexcellence by the IST Future and Emerging Technologies Office. Thenetwork has activities related to research coordination, education andtraining, academia-industry collaboration, and conferences and dis-semination. Today the network involves close to 100 laboratoriesacross Europe.

Further information about the Centre for Autonomous Systemscan be found on the World Wide Web at www.cas.kth.se.

References[Anderson et al., 1999] Andersson, M., Oreback, A., Lindström, M.,

and Christensen, H.I., ISR: An Intelligent Service Robot, in“Intelligent Sensor Based Robotics”, Eds: Christensen, Bunke, andNoltemeier, Springer Verlag, Nov. 1999.

[Austin and Jensfelt, 2000] Austin, D., and Jensfelt, P., Using multiplegaussian hypotheses to represent probability distributions formobilerobot localization, in Proc. of the International Conferenceon Robotics and Automation, (San Francisco, CA, USA), May2000.

[Christensen et al., 2000] Christensen, H., Hüttenrauch, H., and Severinsson-Eklundh, K., Human-robot interaction for servicerobots, in Robotik-2000, (Berlin, Germany), pp. 315-324, VDI,June 2000. (Keynote).

[Christensen and Eklundh, 2000] Christensen, H., and Eklundh, J., Active vision from multiple cues, in Biologically Motivated Computer Vision - BMCV 2000, vol. 1811 of Lecture Notes in Computer Science, pp. 209-216, Seoul, South Korea: SpringerVerlag, May 2000. (keynote).

The center for autonomoussystems is the largest acad-emic facility that does re-search on robotics in Scandi-navia.

<www.cas.kth.se>

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[Ebert et al., 2000] Eberst, C., Andersson, M., and Christensen,H. I.,Vision-based door-traversal for autonomous mobile robots, inIROS-2000, Takamatsu, vol. 1, pp. 620-625, IEEE/RSJ, Novem-ber 2000.

[Egerstedt et al., 2000] Egerstedt, M., Ögren, P., Shakernia, O., andLygeros, J., Toward optimal control of switched linear systems, inIEEE Conference on Decision and Control, (Sydney, Australia),December 2000.

[Hardarsson and Wikander, 2000] Hardarsson F., and Wikander, J.,Robusttorque control of a flexible, geared, DC-motor driven robotjoint, in Proc. 1st IFAC Conference on Mechatronic Systems, 2000.

[Jensfelt et al., 2000a] Jensfelt, P., Austin, D ., Wijk, O., and Andersson, M., Feature based condensation for mobile robotlocalization, in Proc. of the International Conference on Roboticsand Automation, (San Francisco, CA, USA), May 2000.

[Jensfelt et al., 2000b] Jensfelt, P., Austin, D., and Christensen,H. I., Toward task oriented localization, in IAS-6, July 2000.

[Johansson et al., 2000] Johansson, K. H., Lygeros, J., Sastry, S., and Zhang, J., Hybrid automata: A formal paradigm for heterogeneousmodeling, in 11th IEEE International Symposium on Computer-Aided Control Systems Design, (Anchorage, AK), 2000.

[Johansson, 2000] Johansson, K. H., Multi-agent autonomous vehicles and hybrid automata, in Hybrid Control and Automotive Applications Workshop, (Lund, Sweden), May 2000.

[Kragic and Christensen 2000a] Kragic, D., and Christensen, H. I.,Cue integration for manipulation, in Robust vision for vision-basedcontrol of motion (M. Vincze and G. Hager, eds.), SPIE/IEEE Serieson Imaging Science and Engineering, ch. 1, pp. 1-14, New York,Ny - USA:IEEE Press, January 2000.

[Kragic and Christensen, 2000b] Kragic, D., and Christensen, H. I.,A framework for visual servoing, in Intelligent AutonomousSystems - 6 (E. Pagelle, F. Groen, T. Aria, R. Dillmann, and A.Stenz, eds.), (Venezia, IT), pp. 835-842, IAS, IOS Press, July 2000.

[Kragic and Christensen,2000c] Kragic, D., and Christensen, H. I.,Tracking techniques for visual servoign tasks, in ICRA-2000(O.Khatib, ed.), vol. 2, (San Francisco, CA), pp. 1663-1669, IEEE,May 2000.

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[Lindström et al., 2000] Lindström, M., Orebäck, A., andChristensen, H., Berra: A research architecture for service robots,in Intl. Conf. on Robotics and Automation (Khatib, ed.), vol. 4,(San Francisco), pp. 3278-3283, IEEE, May 2000.

[Matveev et al., 2000] Matveev, A., Hu, X., Frezza, R., and Rehbinder, H., Observers for systems with implicit output, IEEE Transactions on Automatic Control, vol. 45, pp. 168-173, January 2000.

[Petersson et al., 2000a] Petersson, L. Austin, D., Kragic, D., and Christensen, H., Towards an intelligent robot system, inProceedings of the Intelligent Autonomous Systems 6, IAS-6,(Venice), pp. 704-709, July 2000.

[Petersson et al., 2000b] Petersson, L., Austin, D., Kragic, D., and Christensen, H. I., Towards an intelligent service robot system, inProc. 6th Intelligent Autonomous Systems, (Venezia, IT), pp. 704-709, IAS, July 2000.

[Rehbinder, 2000b] Rehbinder H., and Sanfridson, M., Integration of off-line scheduling and optimal control, in Proceedings of theEuropean Conference on Real Time Systems, (Stockholm), 2000.

[Rehbinder and Hu, 2000a] Rehbinder and H. Hu, X. Nonlinearstate estimation for rigid body motion with low-pass sensors,Systems & Control Letters, vol. 40, pp. 183-190, 5 July 2000.

[Ridderström et al., 2000]: Ridderström, C., Ingvast , J.,Hardarsson, F., Gudmundsson, M., Wikander and J., Wadden, T.,Thebasic design of the quadruped robot Warp1, in Int. conf. onclimbing and walking robots, Madrid, Spain, 2000.

[Seiz et al., 2000] Seiz, M., Jensfelt, P., and Christensen, H. I., Activeexploration for feature based global localization, in Proc. of theInternational Conference on Intelligent Robots and Systems, 2000.

[Sidenbladh et al., 2000a] Sidenbladh, H., Black, M., and Fleet, D.,Stochastic tracking of 3d human figures using 2d image motion, inEuropean Conference on Computer Vision (D. Vernon, ed.), LectureNotes in Computer Science, (Dublin, Ireland), pp. 712-718,Springer Verlag, 2000.

[Sidenbladh et al., 2000b] Sidenbladh, H., la Torre, F. D., andBlack, M., A framework for modelling the appearance of 3darticulated figues, in IEEE International Conf. on Automatic Faceand Gesture Recognition, (Grenoble, France), pp. 368-375, March2000.

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[Simoncelli et al., 2000] Simoncelli, M., Zunino, G., Christensen,H., and Lange, K. Autonomous poolcleaning: Self localizationand autonomous navigation for cleaning, Autonomous Robots, vol.9,pp. 261-270, December 2000.

[Strandberg et al., 2000] Strandberg, M., Wahlberg, B., and Christensen, H. I., Active perception for control of mobile robots,in Reglermöte 2000, pp. 234-239, Uppsala University.

[Törngren and Redell, 2000] Törngren, M., and Redell, O., Amodelling framework to support the design and analysis ofdistributed real-time control systems, Invited paper, Journal ofMicroprocessors and Microsystems, Elsevier., 2000, Volume 24,Issue 2, 17 April 2000.

[Wijk and Christensen, 2000b] Wijk, O., and Christensen,H. I.,Triangulation-based fusion of sonar data with application in robot-pose tracking, IEEE Trans on Robotics and Automation, vol. 16,pp. 740-752, Dec. 2000.

[Wijk and Christensen, 2000a] Wijk, O., and Christensen, H. I., Localization and navigation of a mobile robot using natural landmarks extracted from sonar data, Robotics and Autonomous Systems, vol. 31, pp. 31-42, April 2000.

[Zhang et al., 2000] Zhang, J., Johansson, K. H., Lygeros, J., andSastry, S. Dynamical systems revisited: Hybrid systems with Zenoexecutions, in Hybrid Systems: Computation and Control (B. Kroghand N. Lynch, eds.), vol. 1790 of Lecture Notes in ComputerScience, Springer-Verlag, New York, 2000.

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Yngve Sundblad

CID, the Centre for user oriented IT Design, brings together research-ers and designers from computer science, humanities, communication,media, and art with industry and user organizations. The center focuson the design and study of usable, interactive IT applications. Themain research themes are connected communities, interactive learningenvironments, and interaction forms, all with user orientation as aleading aspect.

Focus and ThemesThe focus of the research at CID is on the design and study of new,usable, and aesthetically pleasing interactive IT applications forcommunication and cooperation, at work, for learning, and in everydaylife. At CID the aim is to develop and continue the long Swedishtradition of including users early into the design and developmentprocesses.

InterdisciplinarityCID is a competence center where the disciplines include computerscience, humanities, art, and design. CID cooperates with and employspeople from behavioral science departments at Stockholm Univer-sity and Uppsala University; technical and mathematical departmentsat KTH; and design and the following media institutions in Stock-

Centre for user oriented IT Design, CID

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holm; DI (University College of Film, Radio, Television and Thea-tre), GI (the Graphics Institute), Konstfack (University College ofArts, Crafts and Design), Kungliga Konsthögskolan (Royal Univer-sity College of Fine Arts), Filmvetenskap (Department of CinemaStudies), Kungliga Musikhögskolan (Royal University College ofMusic) and SICS (Swedish Institute for Computer Science).

Roots and PartnersCID, established in 1995/96, developed from, and works in closecooperation with, the Interaction and Presentation Laboratory(IPLAB), established in 1985 at Nada. CID belongs to a program of28 competence centres, funded in about equal parts by the Swedishgovernmental funding agency VINNOVA (in cash), by a collectionof 20 industrial and user organization partners (mainly in kind), andby KTH (mainly in kind). Large industrial partners are Ericsson, Saab,Telia (Swedish Telecom), Teracom, and Vattenfall.

Small industrial and consultant company partners are Data-doktorn, Ergolab, Icon Medialab, Lentus, Lernia, TietoEnator andTimeCare. Governmental agency partners are RSV, SIH (SwedishNational Agency for Special Needs Education), Skolverket, SverigeDirekt (public sector Web information), and Utbildningsradion (Swe-dish Educational Broadcasting Company).

User organization partners are the two largest Swedish centraltrade union organizations, LO and TCO, with 3.3 million memberstogether; and the Swedish Handicap Institute.

Researchers and StudentsCID employs 14 senior researchers and 16 research students fromHuman-Computer Interaction, Computer Science, Mathematics,Ethnography, Pedagogy, Psychology, Social Anthropology, CinemaStudies, Media and Journalism, Music, Graphic Design, and IndustrialDesign.

Industrial and user organization partners’ contributions mainlytake the form of researchers’ and developers’ participating in theprojects. Some partners contribute equipment.

A very import resource for CID is also Masters’ students fromKTH and other universities, doing their thesis work at KTH.

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EU Long-term Research ProjectsIn addition to Swedish research support, CID in 2000 and 2001 wasinvolved in four projects funded by the European Community ES-PRIT I3 (Intelligent Information Interfaces) and FET DC (FutureEmerging Technologies – Disappearing Computer) researchinitiatives.

eRENA (1997-2000)The Electronic Arenas project, integrating artistic, technical, and so-cial perspectives, focused on developing inhabited information spaceswhere all participants can be mobile and socially active, such asInhabited TV [Bowers, 2001].

Another strand was Mixed Reality Performance, with a mixtureof physical reality and digital presentation and interaction, whereaudience members as well as performers and artists were able toexplore, interact, communicate, and participate in staged events, nota-bly the Desert Rain performance.

CID coordinated eRENA with partners from media art,sociology, and computer science from GMD Bonn, ZKM Karlsruhe,EPF Lausanne, Université de Genève, Illuminations Ltd., BritishTelecom Labs, and the University of Nottingham.

KidStory (1998-2001)Collaborative Storytelling for Children – With Children (KidStory)was a research project within I3 ESE (Experimental SchoolEnvironments), where educational researchers, computer scientists,children, and teachers are working together to develop and studycomputer support for children’s cooperative storytelling. In theiterative design process, classes of elementary school children (5-8years old) had the role of inventors who suggest improvements,working together with researchers and teachers [Taxén et al., 2001].Drawing and modeling tools were used in a traditional desktopenvironment, extended with multiple mice for cooperative drawingand narration. Other forms of interaction in a complete 3D-environment were developed and studied.

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CID’s partners were the University of Nottingham (coordinator), Uni-versity of Maryland, SICS (Swedish Institute of Computer Science),and schools in Rågsved (Stockholm) and Albany (Nottingham).

InterLiving (2001-2003)The goal of the InterLiving project, together with families, is to studyand develop technologies and artifacts for communication betweengenerations.

InterLiving is coordinated by CID. Research partners are INRIA(Institut National de Recherche en Informatique et en Automatique)and LRI (Laboratoire de Recherche en Informatique) in Paris and theHuman-Computer Interaction Lab at the University of Maryland.Design partners are three families with several intergenerationalhouseholds in greater Stockholm and greater Paris.

InterLiving is funded for three years by the EU programme“Disappearing Computer.The first year has produced ethnographic and design studies oncommunication habits and places within and between the householdsas well as technical “probes” to be brought into the families’ dailylife.

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Shape (2001-2003)Shape is devoted to developing, deploying, and evaluating assembliesof hybrid, mixed reality artifacts in public places, such as museumsand exploratoria. These assemblies aim to provide groups of peoplewith rich sensory experiences – to encourage surprise, curiosity,discovery, interaction and collaboration. Hybrid artifacts exhibit bothphysical and digital features, they combine interactive visual and sonicmaterial with tangible objects and devices, and they can themselvesbe combined to form hybrid assemblies. We are producing newtechniques and technologies that can knit together collections of theseassemblies into engaging and coherent experiences.

Shape is coordinated by CID. The project partners are MixedReality Laboratory, University of Nottingham (U.K.); Work, Inter-action and Technology Research Group, King's College London(U.K.); and Interaction Design Centre University of Limerick(Ireland). The project Coordinator is Professor John Bowers CID,NADA, KTH.

Results and Dissemination

ThesesIn year 2001 four doctoral dissertations and two licentiate theses wereproduced at CID:• Åke Walldius (Ph.D. in Cinema Studies at Stockholm University):

“Patterns of Recollection; The Documentary Meets Digital Media”• Konrad Tollmar (Ph.D. in Computer Science at Stockholm

University/KTH):“Towards CSCW Design in the ScandinavianTradition”

• Angela Boltman (Ph.D. in Educational computing at the Universityof Maryland)“Childrens’ Storytelling Technologies: Differences inElaboration and Recall”

• Björn Eiderbäck (Ph.D. in Computer Science at StockholmUniversity/KTH): “Object Oriented Frameworks with DesignPatterns for Building Distributed Information Sharing”

• Fredrik Winberg (LicTech in Human-Computer Interaction at KTH):“Auditory Direct Manipulation for Blind Computer Users”

• Anders Hedman (LicTech in Human-Computer Interaction at KTH):“Visitor Orientation: Human-Computer Interaction in Digital Places”

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PublicationsIn the years 2000 and 2001 these publications have been produced atCID:• 37 conference reports• 13 journal papers• 12 EU project deliverable reports• 22 other technical reports• 3 video presentations for conferences

PrototypesSeveral prototypes have been developed at CID. Recent examplesare:• VideoSpace: Virtually connected public places at different locations

for close informal collaboration and social interaction, developed, installed and studied between cooperating laboratories, between school children and passengers at an airport and now between three Call Centers in the Stockholm archipelago.

• KidPad: a collaborative story-authoring tool for children thatprovides basic drawing functionality on a zooming canvas. Thenarrative structure of a story is defined by creating hyperlinksbetween objects on the canvas. Developed by the University of Ma-ryland and assisted by CID as part of the KidStory project.

• Auditory direct manipulation: in order to investigate the nature ofauditory direct manipulation, we have implemented an auditory ver-sion of the game “Towers of Hanoi.”

Exhibitions and Performance• In September 2000, as part of a five-year celebration of CID and of

the eRENA project, the Desert Rain performance was given about50 times for an audience of 6 participants at a time.

• CID was invited to exhibit for free in almost 200 sqm at the largestIT trade fair in Stockholm, Connect, in Älvsjö in April 2001.

• CID’s EU projects were exhibited at the I3 fair in Jönköping, eRENAand KidStory in Sept 2000, the Comdex trade fair in Basel, KidStoryin Sept 2001, and at the Disappearing Computer fair in Zürich,InterLiving and Shape in October 2001.

• CID projects were exhibited at the Assisting Devices fair inStockholm/Sollentuna in October 2001.

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• In museum and net exhibitions CID has made contributions with- a futuristic interactive VR installation showing at Expedition Space at the Swedish Museum of National History.- games for people with visual and other impairments at FrITt Fram,IT for impaired, at the Museum of Science and Technology in Stock-holm.- an interactive VR environment on the net for giving school child-ren an opportunity to guide in old Klara, showing central Stock-holm 1899, as part of the town’s 750 years celebration in 2002.

Conclusion and FutureThe existence and results from CID show that user-oriented workover discipline boundaries, university boundaries, industry boundariesand user organization boundaries are both possible (though difficultand time consuming) and fruitful [Lenman & Sundblad 2001]. Thecurrent funding period of CID ends in mid-year 2003. Extension to2005 is planned with continued transfer of people for cooperationover organizational boundaries.

References[Bowers, 2001] Bowers, J., Crossing the Line - a Field Study of

Inhabited Television. BIT, Behaviour & Information Technology,vol. 20, no. 2, pp. 127-140, March-April 2001.

[Lantz, 2001] Lantz, A., Meetings in a distributed group of experts:comparing face-to-face, chat and collaborative virtual environ-ments. BIT, Behaviour & Information Technology, vol. 20, no. 2,pp. 11-117, March-April 2001.

[Lenman and Sundblad, 2001] Lenman, S., & Sundblad, Y.,Five Years' Experience from CID - an Interdisciplinary CompetenceCentre for Design of Usable IT Applications. BIT, Behaviour &Information Technology, vol. 20, no. 2, pp. 81-89, March-April2001.

[Taxén and Naeve, 2001] Taxén, G., Naeve, A., CyberMath:A System for Exploring Open Issues in VR-based EducationConference Abstracts and Applications, pp. 49-51, SIGGRAPH2001 Educators Program, 2001

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[Taxén et al., 2001] Taxén, G., Druin, A., Fast, C., &Kjellin, M., KidStory - a Technology Design Partnership withChildren. BIT, Behaviour & Information Technology, vol. 20, no.2, pp. 119-125, March-April 2001.

[Westerlund et al., 2001] Westerlund, B., Lindquist, S., Sundblad, Y.,Cooperative design of communication support for and with familiesin Stockholm - communication maps, communication robes andlow-tech prototypes, Paper presented at The1st Equator IRC Work-shop on Ubiquitous Computing in Domestic Environments. CID,September 2001.

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Björn Engquist, Harald Hermansson

PSCI is a VINNOVA competence center at Nada in cooperation withthe Department of Information Technology at Uppsala University,UU. Funding comes in roughly equal parts from VINNOVA, KTH/UU, and a number of industrial companies. With the growing capa-bility of realistic computer simulations, scientific computing isbecoming increasingly important in the design and control of newindustrial products and processes and is a suitable topic for acompetence center. Even where scientific computing is essential, it isonly a tool for most industries and thus ideal for pre-competitivecollaboration between companies and academic institutions.

The initial motivation for the creation of PSCI was the need fora center in scientific computing of high international level with anextensive educational component and a focus on industrialapplications. The purpose was to form a link between academic re-search and industrial development. The consequence should be bet-ter-trained students and research results of practical value, includingapplicable software. PSCI is now in the middle of its third stage,which will last until June 2003. Since its start PSCI has developedinto a focused research unit with a recognized profile as a naturalmeeting ground for industry and academia in the field of scientificcomputing. The progress during its six and a half years of operationhas been substantial both in graduate education with industrialrelevance and in the development of an infrastructure for researchand collaboration.

PSCI’s area of research is scientific computing with industrialapplications. This covers the development and analysis of relevantmathematical models for scientific and industrial processes, the ap-proximation of these models by numerical algorithms, and theimplementation of the algorithms on modern computer architectures.Visualization and validation of results are natural parts of the pro-cess.

Parallel and Scientific

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The research is structured in six research programs.

1. Computational Fluid Dynamics (CFD)2. Computational Electromagnetics (CEM)3. Biocomputing (BC)4. High-Performance Computing and Networking (HPCN)5. Computational Material Science (CMS)6. Algorithm Development and Analysis (ADA)

Each program has its own program board with participants from bothindustry and academia. The programs contain a number of researchprojects. Every project has a project leader, either from industry oracademia. Every project includes at least one company, academicadvisor, and student. For each industry, there is an administrative anda technical contact person. The standard PSCI project has at its coreone or more Ph.D. thesis assignment. The programs also containactivities, which are not directly linked to specific projects. Workshopsoften cover broader fields within a program. Examples are the biannualCEM workshops, the annual HPC summer schools by PDC, and thefirst major Scandinavian Conference on Bioinformatics, 1999.

PSCI has chosen not to be restricted to a particular scientificmethodology or a special computational technique. The pragmaticrequirements from industry and the need for broad graduate educationare best met with an open mind with respect to the choice of methods.The natural focusing of the research follows from the set of problemscoming from industry and the questions that are of current interest inthe international scientific community. For PSCI at the present time,this means the following main fields of research.

• Analysis of nonlinear partial differential equations (PDEs) as modelsfor scientific and industrial processes.

• Development and analysis of numerical approximations of thesePDEs.

• Object-oriented programming for scientific computing.• Related research in HPCN: Parallel algorithms, optimal use of

memory hierarchies, visualization, etc.

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The development and analysis of computational algorithms are at thecore of PSCI research. The applied output from this effort is oftenhigh-quality software with direct industrial use. A national initiativefor a state-of the-art CFD-software package is in a pre-study phase.Several Swedish companies are very interested in the developmentof a leading-edge software system for the compressible Navier-Stokesequations. The interested industries include SAAB, Volvo and FOI.An attempt will be made to form broader international cooperationfor this task.

The PSCI projects are closely integrated with the research inNumerical Analysis at Nada. The chapters on computational fluiddynamics, computational electromagnetics, and multi-phase flowstherefore contain material on PSCI projects. If you would like to knowmore about the research projects of PSCI, please order the PSCI Pro-gress Report 1997 - 1999 free of charge, and visithttp://www.psci.kth.se. www.psci.kth.se

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Björn Engquist, Lennart Johnsson

Grids are rapidly developing to be a prerequisite for advanced com-puting and data handling in research institutions, industry and manyother organizations. Grids are assemblies of computers, scientific andmedical instruments, digital databases, equipment for visualizationand mobile communication together with a set of services for theeffective and convenient use of assembled resources.

During the recent period, PDC has developed and deployed gridtechnology in a number of projects including the ongoing and verylarge EU DataGrid project. Other examples are data handling for theSwedish Space Corporation Odin satellite, Large-Scale GenotypingLaboratory at Uppsala Univeristy, and a system for federation of brainimage data in collaboration with, among others, the Karolinska Insti-tutet.

The hardware at PDC has been upgraded during the period.The IBM SP system increased to 165 nodes, with 332 CPUs, peakGflop/s of 270 and 140 GByte of memory. This is including two IBMSP Nighthawk-II nodes managed by PDC for a consortium of depart-ments at KTH (KALLSUP).

A donation by IBM, 16 node PC-cluster, made the foundationof the KTH Linux Laboratory, a joint venture between NADA, PDC,KTH Network Operating Center KALLSUP, IBM, and StockholmBioinformatics Center (SBC). The core of the mission is to stimulateeducational activities and open source development. The IBM clus-ter has been used to develop a scalable and automatic installationprocedure and a scalable system management environment. As anexperimental environment the cluster has successfully been used forvarious experiments with interconnects and protocols, e.g. GigabitEthernet and VIA. Examples of open source projects are Heimdal, aKerberos 5 implementation, and Arla, an AFS implementation.

A 32-processor cluster dedicated to the bioinformatics appli-cations of SBC has been installed. This installation is the first in aseries during the forthcoming three years. A close integration betweenthe cluster and desktop computers at SBC has been achieved by usingLinux as a common platform together with the global file systemAFS.

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PDC’s visualization resources are of continued importance. TheImmersaDesk continues to be used. The Cube, a fully immersive six-surface scientific visualization environment offers researchers newand exciting opportunities. They can visualize and interact with theirdata in new ways, and they can collaborate in new ways with otherresearchers in distant locations.

PDC has provided resources to a large number of researchgroups all over Sweden, in areas such as physics, chemistry, biology,and engineering.

During the years of support from the Swedish Research Coun-cil, PDC has developed an internationally strong center providingservices in all aspects of HPC having a close collaborative relationshipwith its users. The center will continue to develop in that direction,and will continue to serve users in the traditional scientific fields aswell as those outside the traditional areas of scientific computing.

More information about PDC can be found at the PDC website<www.pdc.kth.se>.

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Peter Graham

KTHNoc is a center at NADA with three main areas of responsibility:network operation, education, and research related to InternetTechnologies. Network operation includes running the central nodesfor the Swedish University Network, SUNET, and the Nordic Uni-versity Network, NORDUnet. Education involves the developmentand running of courses on Internet techniques. Research activitiesfocuses on routing protocols, traffic analysis and quality of service.

Network OperationSUNET has been a major Internet provider since 1987. Sunet offersservices such as a large ftp-library and a neutral Web catalogue withaddresses to more than 45.000 Swedish sites that have all been qualitychecked by the KTHNoc staff. The aim is to support the search ofinformation on the Internet. Starting in 2001 KTHNoc has participatedin the planning and first phase of implementing the latest major capa-city increase in Sunet to GigaSunet with 2,5 Gbit/s connections to alluniversities and 10 Gbit/s in the core network, This project it targetedfor completion in September 2002.

In its beginning, Sunet technology quickly evolved into NOR-DUnet, the Nordic University Network, which is the junction of theacademic networks from the five Nordic countries. This network hasnow also been upgraded to rings of 2,5 Gbit/s connections to Den-mark, Norway, and Finland. The corresponding capacity to the Uni-ted States has been increased from 1,2 Gbit/s to 1,9 Gbit/s to thecommodity Internet and 622 Mbit/s dedicated connection to the re-search networks with Abilene and STARTAP. NORDUnet has alsobeen connected to European Research Network, Geant, with 2,5 Gbit/s since December 2001.

EducationKTHNoc has developed and run the course Advanced Internetconstruction‚ a course of five academic credits at NADA. A total ofsix courses have been conducted since 1996 with a total of 120participants from universities, operators, and industry. The Foundationfor Knowledge and Competence Development, KK-Stiftelsen, has

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supported the construction of the necessary router-lab with equipmentfor the course.

Based on the experience from this course, three courses at theundergraduate level have been developed and run for the last twoyears. The courses have been very popular, and the number of sstudentshas been limited mainly by the lab capacity. A dedicated lab was setup at the end of second quarter, greatly improving the availability ofthe lab space and reducing the wear and tear of the equipment (andthe teachers). The lab has also been utilized remotely for coursesoutside the KTH campus with good success.

A new course development activity has been undertaken incooperation with SCINT, the Swedish Center for Internet Technologiesin Kista, to make a course in Advanced Network Operation available.The course forms part of the newly established Masters Program inInternetworking in Kista.

ResearchThere are two main research areas at KTHNOC. One is routingprotocol design and the other is traffic analysis and quality of servicein the Internet. The first is done in cooperation with UTFORS, andthe second is a joint project with the Blekinge Institute of Technologyand financed via a three-year grant from VINNOVA.

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Computing Facilities

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Computing FacilitiesFredrik Jönsson

Looking backThe goal of the systems administration for a long time has been inte-gration of many different computer systems, so that the user has ac-cess to the same environment regardless of system. A lot of the systemswork has consisted of developing software to handle numerousworkstations as efficiently as possible.

This efficiency, however, was coupled with a lack of flexibility;and the focus the last few years has been to reintroduce a certainamount of flexibility while trying to keep the efficiency and avoidtedious, manual administrative work.

The introduction of Windows systems at NADA in the last fewyears has meant a loss of some of the environment’s inegration. TheWindows system is tightly integrated in itself, much as our Unixsystems have always been; however, the lack of compatibility betweenWindows and anything else –, together with our previously less com-mon dedication to Kerberos authentication and the AFS network filesystem – has made it hard to provide reasonable cross-system inte-gration. This is not very different from how it always has been withour Mac OS machines, however, the introduction of Mac OS X haschanged this situation dramatically, and we can now provide a totaland seamless integration between our Mac OS and Unix environments.Windows 2000 has given us some opportunity to integrate theenvironment, but only very partially as yet. There are some hopefulsigns for the future, such as Microsoft’s recent publication of theWindows-specific parts of the Kerberos tickets.

Apart from the increased diversity of systems, there has beenan increase of diversity of usage patterns and the need for supportingmany new software systems. The reason is the integration of the re-search group for media technology with NADA, as well as the neweducation programs in media technology, Medieteknologi, Publi-ceringsteknik and AFM. This has primarily affected the Windowsand Mac OS systems that these user categories heavily depend on,and multimedia software products are notoriously bad from a systemmaintenance point of view.

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These groups are traditionally heavily focused on mobile computing,which adds yet more complexity.

We've directed quite a lot of resources to our help desk, Delfi,during the last couple of years to provide highly available, professionalsystem support. Today three members work full time in Delfi, and weare also trying to dedicate time from the systems staff to work withinformation and education.

Recent Major ChangesDuring 2001 we made some rather large changes to the environment.We moved all our Windows clients from NT 4.0 to Windows 2000.We upgraded all Sun workstations from Solaris 2.6 to Solaris 8. Inaddition to the OS upgrade, we also reorganized the file system onthe workstations. This change improves performance, decreases thedependency of the network file system for commonly used read-only data, and provides increased flexibility as mentioned above. TheMac OS group has primarily been busy preparing for Mac OS X,which is not only a large and complex upgrade from Mac OS 9.x, butalso a completely new operating system. The network also got a ma-jor overhaul in 2001 with an upgrade of many switches and theacquisition of a new router to provide a 1 Gbit backbone and 100Mbit Fast Ethernet connections to all clients.

Current systemThe computer system at NADA currently consists of almost a thousandnodes. The network itself contains about 80 of these and is currentlyprimarily made of Cisco equipment. After a major upgrade in 2001all clients are connected with 100 Mbit Fast Ethernet connections toswitches on 1 Gbit Ethernet interconnects. The networks are connectedto 1 Gbit interfaces on a Cisco 6500 router, which also has 1 Gbitconnections to the KTH network. The old Cisco 7513 Fast Ethernetrouter provides a 100 Mbit Fast Ethernet hot standby backup. Thenetwork is not heavily loaded. In fact, the only activities currentlyexercising the network to any noticeable level at all are file systembackups and system installations over the network. Still, the increasedbandwidth also means a decrease of latency, and we can expectnetwork usage to increase as we try to centralize resources.

We have been looking into wireless networking for some time,and we will deploy wireless networks to some parts of NADA in the

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near future. We are also looking into a step-up to Gbit connectionsfor some of the server resources.

About 20 % of the machines on the network are Windowsmachines, almost all running Windows 2000; a bit more than 10 %Mac OS systems and are now migrating to Mac OS X; and the restare Unix workstations, primarily Sun Sparc systems running Solaris8 but also some RedHat Linux machines. Students have access to allenvironments except Linux, but we are planning a lab room for Linuxcomputers in the near future.

We have about 100 servers in the system. By tradition, theNADA server environment has consisted of many small servers, oftenolder workstations serving only one or at least very few purposes,hence the large number of servers. These are combined with somelarger machines mainly used as file servers. The trend is currently tomove toward more dedicated server hardware as the demands ofavailability and performance increases. About a dozen servers arededicated Windows servers, with approximately the same number ofMac OS servers. The rest are Sun Sparcs.

Back to the FutureWe need to address problems resulting from the increased diversityof the environment. Primarily this concerns data storage, which needsto return to a more centralized model. Because it is hard to achieveproper backup procedures for mobile computers and local disks onworkstations scattered over the network, we have already had casesof data losses. Two reasons for this are the users’ lack of understan-ding of the risks involved or of how the backup procedures work,and also the lack of fault tolerant hard- and software systems.

Increasingly scattered users force us to look at other centralizedsolutions, such as thin client computing. Modern solutions provideinteresting capabilities, such as roaming sessions. These ”new”approaches also meet the wishes for systems that produce less heatand noise by users who do not really need the functionality of a work-station. But it is not only interesting for users with low systemrequirements. On the high end, centralized resources mean that wecan provide shared machines capable of managing working sets thatwe never can support with individual workstations.

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Internally, the systems staff needs to look at, plan for, and accomplisha program of proper education of its members in order to continue tomeet the high demands of competent system administration as wellas to meet the personal satisfaction of the staff members themselves.