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  • 1.
    Abrikosov, Igor A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Steneteg, Peter
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Hultberg, Lasse
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Hellman, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Yu Mosyagin, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Department of Theoretical Physics and Quantum Technologies, National Research, Technological University MISiS, Moscow, Russia.
    Lugovskoy, Andrey V.
    Department of Theoretical Physics and Quantum Technologies, National Research, Technological University MISiS, Russia.
    Barannikova, Svetlana A.
    Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Science, Tomsk, Russia; Department of Physics and Engineering, Tomsk State University, Tomsk, Russia.
    Finite Temperature, Magnetic, and Many-Body Effects in Ab Initio Simulations of Alloy Thermodynamics2013In: TMS2013 Supplemental Proceedings, John Wiley & Sons, 2013, 617-626 p.Chapter in book (Refereed)
    Abstract [en]

    Ab initio electronic structure theory is known as a useful tool for prediction of materials properties. However, majority of simulations still deal with calculations in the framework of density functional theory with local or semi-local functionals carried out at zero temperature. We present new methodological solution.s, which go beyond this approach and explicitly take finite temperature, magnetic, and many-body effects into account. Considering Ti-based alloys, we discuss !imitations of the quasiharmonic approximation for the treatment of lattice vibrations, and present an accurate and easily extendable method to calculate free ,energies of strongly anharmonic solids. We underline the necessity to going beyond the state-of-the-art techniques for the determination of effective cluster interactions in systems exhibiting mctal-to-insulator transition, and describe a unified cluster expansion approach developed for this class of materials. Finally, we outline a first-principles method, disordered local moments molecular dynamics, for calculations of thermodynamic properties of magnetic alloys, like Cr1-x,.AlxN, in their high-temperature paramagnetic state. Our results unambiguously demonstrate importance of finite temperature effects in theoretical calculations ofthermodynamic properties ofmaterials.

  • 2.
    Abrikosov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. National University of Science and Technology MISIS, Russia.
    Ponomareva, A. V.
    National University of Science and Technology MISIS, Russia.
    Steneteg, Peter
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Barannikova, S. A.
    National University of Science and Technology MISIS, Russia; National Research Tomsk State University, Russia; SB RAS, Russia.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Recent progress in simulations of the paramagnetic state of magnetic materials2016In: Current opinion in solid state & materials science, ISSN 1359-0286, E-ISSN 1879-0348, Vol. 20, no 2, 85-106 p.Article, review/survey (Refereed)
    Abstract [en]

    We review recent developments in the field of first-principles simulations of magnetic materials above the magnetic order disorder transition temperature, focusing mainly on 3d-transition metals, their alloys and compounds. We review theoretical tools, which allow for a description of a system with local moments, which survive, but become disordered in the paramagnetic state, focusing on their advantages and limitations. We discuss applications of these theories for calculations of thermodynamic and mechanical properties of paramagnetic materials. The presented examples include, among others, simulations of phase stability of Fe, Fe-Cr and Fe-Mn alloys, formation energies of vacancies, substitutional and interstitial impurities, as well as their interactions in Fe, calculations of equations of state and elastic moduli for 3d-transition metal alloys and compounds, like CrN and steels. The examples underline the need for a proper treatment of magnetic disorder in these systems. (C) 2015 Elsevier Ltd. All rights reserved.

    The full text will be freely available from 2018-04-01 13:15
  • 3. Ahmad, Tausif
    et al.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Hybrid Color Halftoning2010Conference paper (Refereed)
  • 4.
    Ahmed, Hamad
    et al.
    Centre for Plasma Physics, Queen’s University of Belfast, Belfast BT7 1NN, UK.
    Doria, Domenico
    Centre for Plasma Physics, Queen’s University of Belfast, Belfast BT7 1NN, UK.
    Dieckmann, Mark Eric
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Sarri, Gianluca
    Centre for Plasma Physics, Queen’s University of Belfast, Belfast BT7 1NN, UK.
    Romagnani, Lorenzo
    LULI, École Polytechnique, CNRS, CEA, UPMC, Palaiseau, France.
    Bret, Antoine
    ETSI Industriales, Universidad Castilla La Mancha, E-13 071 Ciudad Real, Spain.
    Cerchez, M
    Institute for Laser and Plasma Physics, University of Düsseldorf, Germany.
    Giesecke, AL
    Institute for Laser and Plasma Physics, University of Düsseldorf, Germany.
    Ianni, E
    Centre for Plasma Physics, Queen’s University of Belfast, Belfast BT7 1NN, UK.
    Kar, Satya
    Centre for Plasma Physics, Queen’s University of Belfast, Belfast BT7 1NN, UK.
    Notley, Margaret
    Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX, UK.
    Prasad, R
    Centre for Plasma Physics, Queen’s University of Belfast, Belfast BT7 1NN, UK.
    Quinn, Kevin
    Centre for Plasma Physics, Queen’s University of Belfast, Belfast BT7 1NN, UK.
    Willi, Oswald
    Institute for Laser and Plasma Physics, University of Düsseldorf, Germany.
    Borghesi, Marco
    Centre for Plasma Physics, Queen’s University of Belfast, Belfast BT7 1NN, UK.
    Experimental Observation of Thin-shell Instability in a Collisionless Plasma2017In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 834, no 2, L21Article in journal (Refereed)
    Abstract [en]

    We report on the experimental observation of the instability of a plasma shell, which formed during the expansion of a laser-ablated plasma into a rarefied ambient medium. By means of a proton radiography technique, the evolution of the instability is temporally and spatially resolved on a timescale much shorter than the hydrodynamic one. The density of the thin shell exceeds that of the surrounding plasma, which lets electrons diffuse outward. An ambipolar electric field grows on both sides of the thin shell that is antiparallel to the density gradient. Ripples in the thin shell result in a spatially varying balance between the thermal pressure force mediated by this field and the ram pressure force that is exerted on it by the inflowing plasma. This mismatch amplifies the ripples by the same mechanism that drives the hydrodynamic nonlinear thin-shell instability (NTSI). Our results thus constitute the first experimental verification that the NTSI can develop in colliding flows.

  • 5.
    Akner-Kohler, Cheryl
    et al.
    Grythytte Academy, Örebro University, Sweden.
    Tibell, Lena
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Aesthetics and nanostructure2011In: International Innovation, ISSN 2041-4552, 97-99 p.Article in journal (Other (popular science, discussion, etc.))
  • 6.
    Akram Hassan, Kahin
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Rönnberg, Niklas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Forsell, Camilla
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Johansson, Jimmy
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Centre for Climate Science and Policy Research, CSPR.
    On the Performance of Stereoscopic Versus Monoscopic 3D Parallel Coordinates2016Conference paper (Refereed)
    Abstract [en]

    This work presents the results from an evaluation of stereoscopic versus monoscopic 3D parallel coordinates. The objective of the evaluation was to investigate if stereopsis increases user performance. The results show that stereoscopy has no effect at all on user performance compared to monoscopy. This result is important when it comes to the potential use of stereopsis within the information visualization community.

  • 7.
    Alberti, Marco
    et al.
    Dept. of Computer Science, Universidade Nova de Lisbona, Lisbon.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Pereira, Luis M
    Dept. of Computer Science, Nova Universidade de Lisboa, Lisbon.
    Observation Strategies for Event Detection with Incidence on Runtime Verification2010In: Experimental evaluation of algorithms for solving problems with combinatorial explosion / [ed] Marco Gavanelli and Toni Mancini, Bologna: Ceur , 2010Conference paper (Refereed)
  • 8.
    Alberti, Marco
    et al.
    Dept. of Computer Science, Nova Universidade de Lisboa, Lisbon.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Pereira, Luis M
    Dept. of Computer Science, Nova Universidade de Lisboa, Lisbon.
    Observation Strategies for Event Detection with Incidence on Runtime Verification: Theory, Algorithms, Experimentation2011In: Annals of Mathematics and Artificial Intelligence, ISSN 1012-2443, E-ISSN 1573-7470, Vol. 62, no 3-4, 161-186 p.Article in journal (Refereed)
    Abstract [en]

    Many applications (such as system and user monitoring, runtime verification, diagnosis, observation-based decision making, intention recognition) all require to detect the occurrence of an event in a system, which entails the ability to observe the system. Observation can be costly, so it makes sense to try and reduce the number of observations, without losing full certainty about the event’s actual occurrence. In this paper, we propose a formalization of this problem. We formally show that, whenever the event to be detected follows a discrete spatial or temporal pattern, then it is possible to reduce the number of observations. We discuss exact and approximate algorithms to solve the problem, and provide an experimental evaluation of them. We apply the resulting algorithms to verification of linear temporal logics formulæ. Finally, we discuss possible generalizations and extensions, and, in particular, how event detection can benefit from logic programming techniques.

  • 9.
    Alferes, José Julio
    et al.
    Centro de Inteligência Artificial - CENTRIA Departamento de Informática, Faculdade de Ciências e Tecnologia, Caparica, Portugal .
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology. Centro de Inteligência Artificial - CENTRIA Departamento de Informática, Faculdade de Ciências e Tecnologia, Caparica, Portugal.
    Pereira, Luis Moniz
    Centro de Inteligência Artificial - CENTRIA Departamento de Informática, Faculdade de Ciências e Tecnologia, Caparica, Portugal.
    A compilation of updates plus preferences2002In: Logics in Artificial Intelligence 8th European Conference, JELIA 2002 Cosenza, Italy, September 23–26, 2002 Proceedings / [ed] Sergio Flesca, Sergio Greco, Giovambattista Ianni and Nicola Leone, Springer Berlin/Heidelberg, 2002, Vol. 2424, 62-74 p.Chapter in book (Refereed)
    Abstract [en]

    We show how to compile programs formalizing update plus preference reasoning into standard generalized logic programs and show the correctness of the transformation.

  • 10.
    Algmark, Carl
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Eskilsson, Mattias
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Omgivningspåverkan vid sänkhammarborrning2014Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sänkhammarborrning är en metod som används för att utföra grundläggning med stålpålar. Metoden blir allt vanligare i Svenska tätbebyggda miljöer där krav ställs på låg omgivningspåverkan. Vid sänkhammarborrning borras ett foderrör av stål ner genom jordlagren till avsett djup, oftast till bärkraftigt berg. Foderröret lämnas sedan kvar, armeras, gjuts och utgör sedan själva pålen. Borrmaskinen består bland annat av en hammare som arbetar nere i hålet och drivs av antingen vatten eller luft. Borrföretagen har ofta tillgång till flera olika borrsystem men det saknas ibland underlag och forskning för hur olika borrsystem och metoder påverkar mark och omgivning vilket kan skapa en osäkerhet i projekteringsfasen och oförutsedda problem i utförandestadiet. Sänkhammarborrning anses ha en mindre massförträngande effekt men ger ändå en viss omgivningspåverkan både ovan och under mark. I den här studien har omgivningspåverkan under mark behandlats. Tre störningskällor har undersökts; vibrationer, uppspolning och trycksättning. Syftet har varit att teoretiskt undersöka hur vattendrivet- och luftdrivet sänkhammarborrsystem påverkar undergrunden i samband med att stålrörspålar installeras. För att nå syftet har en litteraturstudie och en intervjustudie genomförts. Även två fältbesök har gjorts. Litteratur och intervjuer har sedan analyserats med utgångspunkt i de tre nämnda fenomenen. Resultatet visar att de viktigaste faktorerna som påverkar hur stor omgivningspåverkan blir är markförutsättningar, maskinutrustning och utförandet. Vattendriven borrning visar sig löpa mindre risk att påverka omgivningen när det gäller uppspolning och trycksättning men om borrningen utförs på rätt sätt kan omgivningspåverkan undvikas även vid luftdriven borrning. De två borrsystemen har olika slagenergier och slagfrekvenser dock kan inga slutsatser dras av hur detta påverkar vibrationsnivåerna. Ett antal åtgärder finns för att minimera omgivningspåverkan, det handlar framförallt om att välja rätt borrsystem samt att borrningen utförs på rätt sätt.

  • 11.
    Ander, Julia
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Coating actions for an intersection affected by repeated rutting.2013Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Korsningar, busshållplatser, söderbackar och lastkajer är ytor med extrem påkänning på grund av hög trafikbelastning, låg hastighet, accelerationer, inbromsningar, svängningar, spårbundenhet och utsatthet för höga temperaturer. Den speciella lastsituationen riskerar orsaka spårbildning, vilket är det vanligaste problemet i korsningar. Genom att anpassa beläggningen efter den utsatta ytan så kan projektören påverka vägens funktion och livslängd. Syftet med detta examensarbete var att studera vilka beläggningsåtgärder som är lämpliga för utsatta körytor såsom korsningar och busshållplatser samt att se vad som orsakar skadebilden i en skadedrabbad korsning. Vidare var syftet att jämföra tre beläggningsalternativ för att se vilket som var mest fördelaktigt ur ett livslängds- och kostnadsperspektiv. Frågeställningarna var följande: 1. Vilka beläggningar är lämpliga för särskilt utsatta körytor såsom korsningar och busshållplatser? 2. Vad orsakar skadebilden vid frånfarten på Malmslättsvägen vid korsningen Malmslättsvägen/ Kaserngatan? 3. Vilken beläggningsåtgärd av ABS11, Densiphalt och PMA är bäst ur ett livslängd- och kostnadsperspektiv under 20 år för korsningen Malmslättsvägen/ Kaserngatan? För att besvara frågeställningarna gjordes litteraturstudier samt en fallstudie i form av okulär bedömning och balkanalys i det aktuella vägsnittet. Dessutom jämfördes livslängd och kostnader mellan beläggningsalternativen i PMS Objekt respektive genom en ekonomisk beräkningsmetod. Resultatet visade att ett bindlager kan uppta de skjuvkrafter som uppstår på utsatta ytor och förhindrar därmed sprickbildning och deformationer. CBÖ och platsgjuten betong har i studier visat begränsa spårbildning. Densiphalt är lämplig som beläggning på utsatta ytor och ger samtidigt ytan motståndskraft mot olja och bensin. IM är starkare, styvare och mindre deformationsbenägen än en vanlig asfalt och är därför lämplig på högtrafikerade vägar. Fallstudien på det aktuella vägsnittet visade att skadebilden hade två orsaker. Dels fanns ett ytslitage som var orsakat av den spårbundna dubbdäckstrafiken. Dessutom förekom plastisk deformation i det andra och tredje asfaltlagret till följd av otillräcklig stabilitet i asfaltmassan med hänsyn till den långsamtgående och stillastående trafiken. De obundna lagren var till synes opåverkade vid balkanalysen. Jämförelsen mellan beläggningsalternativen visade att Densiphalt hade längst livslängd följt av PMA och ABS11. Kostnadsmässigt hade PMA lägst annuitet följt av Densiphalt och ABS11. Orsaken till att ABS11 var dyrast var troligen behovet av mellanliggande akutåtgärder i form av gjutasfalt. Slutsatsen var att kompletterande bindlager, CBÖ, PMA, Densiphalt, betong och IM var lämpliga beläggningar för särskilt utsatta ytor. Skadebilden vid det undersökta vägsnittet bedömdes bero på ytslitage på grund av spårbunden dubbdäckstrafik samt plastisk deformation till följd av tung trafik. Densiphalt hade längst livslängd och PMA hade lägst annuitet. Konventionell ABS11 var sämst ur både livslängds- och kostnadsperspektiv, vilket bedömdes bero på behovet av mellanliggande akutåtgärder i form av gjutasfalt.

  • 12.
    Anderson, Camilla
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Andersson, Frida
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Subscribers loyalty for newspapers - a study of Östgöta Correspondentens weekend supplement2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Upplagesiffrorna för den tryckta dagstidningen har minskat under flera år. I Sverige är det ett stort problem då prenumerationen av den tryckta dagstidningen fortfarande är tidningsföretagens största inkomstkälla. Detta gör att det är av stor vikt för tidningsföretagen att hitta ett sätt att behålla dessa kunder. I denna studie har det undersökts om utformningen av en bilaga kan bidra till att prenumeranterna blir mer lojala. Studien har utförts i sammanbete med Östgöta Correspondenten och dess helgbilaga Paus Weekend. För att svara på syftet delades studien upp i två delproblem: vad har Östgöta Correspondentens nuvarande prenumeranter för attityder till Paus Weekend och huvudtidningen samt om det finns andra liknande bliagor som uppnått ökad kundlojalitet.

  • 13.
    Anderson, Trevor
    et al.
    Purdue University, USA.
    Schönborn, Konrad
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    du Plessis, Lynn
    University of KwaZulu-Natal, South Africa.
    Gupthar, Abindra
    University of KwaZulu-Natal, South Africa.
    Hull, Tracy
    University of KwaZulu-Natal, South Africa.
    Identifying and Developing Students' Ability to Reason with Concepts and Representations in Biology2013In: Multiple Representations in Biological Education / [ed] D.F. Treagust and C.-Y. Tsui, Springer Science+Business Media B.V., 2013, -390 p.Chapter in book (Refereed)
    Abstract [en]

    This new publication in the Models and Modeling in Science Education series synthesizes a wealth of international research on using multiple representations in biology education and aims for a coherent framework in using them to improve higher-order learning. Addressing a major gap in the literature, the volume proposes a theoretical model for advancing biology educators’ notions of how multiple external representations (MERs) such as analogies, metaphors and visualizations can best be harnessed for improving teaching and learning in biology at all pedagogical levels.The content tackles the conceptual and linguistic difficulties of learning biology at each level—macro, micro, sub-micro, and symbolic, illustrating how MERs can be used in teaching across these levels and in various combinations, as well as in differing contexts and topic areas. The strategies outlined will help students’ reasoning and problem-solving skills, enhance their ability to construct mental models and internal representations, and, ultimately, will assist in increasing public understanding of biology-related issues, a key goal in today’s world of pressing concerns over societal problems about food, environment, energy, and health. The book concludes by highlighting important aspects of research in biological education in the post-genomic, information age. 

  • 14.
    Andersson, Annika
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Björndahl, Caroline
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Säsongssmart - Att kommunicera mat i säsong2017Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
  • 15.
    Andersson Granberg, Tobias
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. CARER.
    Granlund, Rego
    SICS East Swedish ICT AB, Sweden.
    Lindborg, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ulander, Anna
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. CARER.
    Dynamisk planering av räddningstjänst2014Report (Other academic)
    Abstract [sv]

    Dynamisk planering innebär bland annat att brandmännen delar in sig i mindre grupper än traditionellt. Dessa kan då arbeta förebyggande med utbildning eller placeras strategiskt till exempel i närheten av olycksdrabbade vägsträckor, för att snabbare kunna nå fram till en olycksplats. Då en olycka inträffar larmas de brandmän som snabbast kan nå fram, och det kan vara nödvändigt att larma flera olika grupper.

    En utmaning vid dynamisk planering är att planeringssituationen blir svårare. Det är inte längre självklart vilka brandmän som ska larmas till en viss olycka. Det kan också vara svårt att hitta de bästa placeringarna för brandmän som snabbt ska kunna göra en insats.

    I projektet har vi utvecklat och utvärderat datorbaserade verktyg som kan stödja dynamisk planering av räddningstjänst.

    Bland verktygen finns en beredskapskalkylator med tillhörande visualisering, vilken beräknar beredskapen som en funktion av tiden det tar för de nödvändiga resurserna att nå fram till en viss typ av olycka och sannolikheten för att olyckan ska inträffa i närområdet. Ett annat verktyg kan ge förslag på vilka resurser som bör skickas till en olycksplats för att de ska komma fram så fort som möjligt. Ett tredje verktyg kan ge förslag på hur fordon och personal dynamiskt bör placeras för att beredskapen ska förbättras, dvs. de ska kunna nå fram så fort som möjligt till de platser där det är störst sannolikhet att en olycka kommer att inträffa.

    Verktygen har utvärderats genom två experimentserier. I experimenten testades mänskligt beslutsfattande i en simulerad räddningstjänstmiljö. I den första serien fick personal från olika räddningstjänster prova på dynamisk planering utan hjälp av de datorbaserade verktygen. I den andra serien fick andra räddningstjänster köra samma scenarier, men då ta hjälp av de i projektet utvecklade verktygen.

    Resultaten visar att verktygen kan hjälpa räddningstjänsten med planeringen av beredskapen, men också att det finns risk att detta sker på bekostnad av att planeringen tar något längre tid. En tydlig majoritet av de deltagande räddningstjänstbefälen var positivt inställda till de utvecklade verktygen och tyckte verktyg av detta slag skulle kunna hjälpa dem i det dagliga arbetet.

    Resultaten tydliggör också att olika personer – till och med nära kollegor inom samma räddningstjänst – uppfattar begreppet beredskap på olika sätt. Det visade sig dock att beredskapsvisualiseringen kan bidra till att denna skillnad i uppfattning minskar; i den andra experimentserien, där de hade tillgång till detta verktyg, minskade variationerna i bedömningarna och deltagarnas uppfattningar stämde bättre överens med den beräknade beredskapen.

  • 16.
    Andersson Granberg, Tobias
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Lundberg, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. CARER.
    Ulander, Anna
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Rego, Granlund
    SICS Swedish ICT, Linkoping, Sweden.
    Supporting dispatch decisions for the fire and rescue services2015In: 2015 IEEE 18th International Conference on Intelligent Transportation Systems, IEEE conference proceedings, 2015, 2562-2567 p.Conference paper (Refereed)
    Abstract [en]

    Decision support tools for efficient dispatching of fire and rescue resources are developed and evaluated. The tools can give suggestions about which resources to dispatch to new accidents, and help the decision makers in evaluating the current preparedness for handling future accidents. The tools are evaluated using simulation game based experiments, with players from the fire and rescue services. The results indicate that the tools can help the fire and rescue services in identifying the closest resources to new accidents, and to select resources that preserve the preparedness in the area. However, the results also indicate that there is a risk that the tools increase the decision time. 

  • 17.
    Andersson, Johanna
    et al.
    Linköping University, Department of Social and Welfare Studies, Learning, Aesthetics, Natural science. Linköping University, Faculty of Educational Sciences.
    Tibell, Lena
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Educational Sciences. Linköpings universitet.
    Exploring childrens' views of what's inside the body2012Conference paper (Refereed)
    Abstract [en]

    The importance of living a healthy life in an everyday context is promoted in schools and preschools. The discussion often focuses on what food is healthy, and that one should eat enough but not too much. The connection between food and beverages and their role in the body is seldom discussed. Students’ ideas about how the human body functions have been investigated in several studies but few have focused on young children. In this study, we investigate young children’s conceptions related to this topic and how their ideas develop. Seventy-nine pre- and primary school children, aged 4-11, participated in individual focus interviews wherein the children were asked to draw and explain their understanding. Our results confirm several findings observed by other workers. However, in contrast with earlier studies, 10 of seventeen 4-5 year-old children indicated the stomach, and more than half of those children described how food can be utilized in the body to extract energy. Furthermore, the brain was among the most commonly mentioned organs cross all age groups. Interestingly, the level of expertise varied and did not covariate with age. For example, five of eight of the 4 year-old children draw 5-8 organs, while a single 10 year-old child could only mention three. Similarly, two of thirteen 7-year old children provided an almost completely correct description of the digestive tract and its function, while most of the older children expressed a much less developed understanding. The results reflect the wide range of different conceptual ideas that teachers confront in a day-to-day classroom context.

  • 18.
    Andersson, Johanna
    et al.
    Linköping University, Department of Social and Welfare Studies, Learning, Aesthetics, Natural science. Linköping University, Faculty of Educational Sciences.
    Tibell, Lena A.E.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Educational Sciences. Linköpings universitet.
    Children's reasoning and representations about living and non-living things2013Conference paper (Refereed)
    Abstract [en]

    Understanding of the concept ‘life’ and what characterise ‘living things’ is important as a foundation for learning in biology. In a more general view, this understanding can make children develop awareness, respect and responsibility for life as members of a society and in decision making for sustainable development. The present pilot study aim to investigate 5-6 year old pre-school children’s reasoning and representations about living and nonliving things. In cognitive developmental research, the concept of life is well investigated but, questions still remain regarding how children reason around and represent these concepts. Previous research has found that children have difficulties in including plants as living things. Moreover, it is found that young children include e.g. the sun, clouds and rocks as living things. The methods that have been used are often quantitative and use picture-cards with different objects for the children to categorize. In the present pilot study a modified methodology was applied. Children’s drawings of what they consider as living and non-living were collected and picture-cards were used as point of departure for reasoning. In interviews the children were encouraged to explain and express their ideas. The drawings and the cards mainly worked as a meaning making tool for the children. Results from the study will be presented and discussed. 

  • 19.
    Andersson, Kaisa
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Björk, Carolina
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Specific conditions for marketing of non-profit organizations conducting fundraising2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Många ideella organisationer behöver bidrag och stöd för att kunna bedriva sitt arbete. Därmed blir det viktigt att vara synliga och sticka ut från mängden för att få människors stöd. Syftet med denna studie är att undersöka specifika förutsättningar för marknadsföring av ideella organisationer som bedriver insamling i Sverige. Genom kvalitativa intervjuer undersöktes hur väl Barncancerfondens och Kvinna till Kvinnas uppfattningar överensstämmer med teorier som finns inom området. Slutsatser som överensstämde med litteraturen var att ideella organisationer ofta har som mål att nå en mycket bred publik eller till och med hela allmänheten. Men studien visar även att Barncancerfonden och Kvinna till Kvinna arbetar strategiskt med målgrupper för att rikta insamling och informationsarbete, trots att det finns en vilja att nå ut brett. Inom ideella organisationer är det även svårt att modifiera budskapet, eftersom det måste spegla verksamheten. Hur organisationen påverkas av detta beror delvis på vilken typ av ämne som organisationen berör eftersom det med ett intresseväckande ämne är lättare att nå ut. En annan specifik förutsättning är att gåvor ofta är en osynlig handling som gynnar någon annan. Avsaknaden av produkt nämns av organisationerna som något marknadsföringen måste bemöta, vilket kan ske på olika sätt. Ideella verksamheter normalt uppfattas ha ett gott syfte vilket gör allmänheten mer mottaglig för budskapen.

  • 20.
    Andersson, Magnus
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Lantz, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Ebbers, Tino
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV). Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Quantitative Assessment of Turbulence and Flow Eccentricity in an Aortic Coarctation - Impact of Virtual Interventions2015In: Cardiovascular Engineering and Technology, ISSN 1869-408X, E-ISSN 1869-4098, Vol. 6, no 6, 281-293 p.Article in journal (Refereed)
    Abstract [en]

    Turbulence and flow eccentricity can be measured by magnetic resonance imaging (MRI) and may play an important role in the pathogenesis of numerous cardiovascular diseases. In the present study, we propose quantitative techniques to assess turbulent kinetic energy (TKE) and flow eccentricity that could assist in the evaluation and treatment of stenotic severities. These hemodynamic parameters were studied in a pre-treated aortic coarctation (CoA) and after several virtual interventions using computational fluid dynamics (CFD), to demonstrate the effect of different dilatation options on the flow field. Patient-specific geometry and flow conditions were derived from MRI data. The unsteady pulsatile flow was resolved by large eddy simulation (LES) including non-Newtonian blood rheology. Results showed an inverse asymptotic relationship between the total amount of TKE and degree of dilatation of the stenosis, where turbulent flow proximal the constriction limits the possible improvement by treating the CoA alone. Spatiotemporal maps of TKE and flow eccentricity could be linked to the characteristics of the jet, where improved flow conditions were favored by an eccentric dilatation of the CoA. By including these flow markers into a combined MRI-CFD intervention framework, CoA therapy has not only the possibility to produce predictions via simulation, but can also be validated pre- and immediate post treatment, as well as during follow-up studies.

  • 21.
    Andersson, Magnus
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Lantz, Jonas
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    NON-INVASIVE INTERVENTION PLANNING OF STENOTIC FLOWS USING SCALE-RESOLVED IMAGE-BASED COMPUTATIONAL FLUID DYNAMICS2013Conference paper (Refereed)
  • 22.
    Andersson, Magnus
    et al.
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
    Lantz, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Karlsson, Matts
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Turbulence Quantification of Stenotic Blood Flow Using Image-Based CFD: Effect of Different Interventions2014In: WCB 2014, 2014Conference paper (Other academic)
    Abstract [en]

    Turbulent blood flow is often associated with some sort of cardiovascular disease, e.g. sharp bends and/or sudden constrictions/expansions of the vessel wall. The energy losses associated with the turbulent flow may increase the heart workload in order to maintain cardiac output (CO). In the present study, the amount of turbulent kinetic energy (TKE) developed in the vicinity of an aortic coarctation was estimated pre-intervention and in a variety of post-intervention configurations, using scale-resolved image-based computational fluid dynamics (CFD). TKE can be measured using magnet resonance imaging (MRI) and have also been validated with CFD simulations [1], i.e. a parameter that not only can be quantified using simulations but can also be measured by MRI.

    Patient-specific geometry and inlet flow conditions were obtained using contrast-enhanced MR angiography and 2D cine phase-contrast MRI, respectively. The intervention procedure was mimicked using an inflation simulation, where six different geometries were obtained. A scale-resolving turbulence model, large eddy simulation (LES), was utilized to resolve the largest turbulent scales and also to capture the laminar-to-turbulent transition. All cases were simulated using baseline CO and with a 20% CO increase to simulate a possible flow adaption after intervention.

    For this patient, results shows a non-linear decay of the total amount of TKE integrated over the cardiac phase as the stenotic cross-sectional area is increased by the intervention.  Figure 1 shows the original segmented geometry and two dilated coarctation with corresponding volume rendering of the TKE at peak systole. Due to turbulent transition at a kink upstream the stenosis further dilation of the coarctation tends to restrict the TKE to a plateau, and continued vessel expansion may therefore only induce unnecessary stresses onto the arterial wall. 

    This patient-specific non-invasive framework has shown the geometrical impact on the TKE estimates. New insight in turbulence development indicates that the studied coarctation can only be improved to a certain extent, where focus should be on the upstream region, if further TKE reduction is motivated. The possibility of including MRI in a combined framework could have great potential for future intervention planning and follow-up studies.  

    [1] J. Lantz, T. Ebbers, J. Engvall and M. Karlsson, Numerical and Experimental Assessment of Turbulent Kinetic Energy in an Aortic Coarctation, Journal of Biomechnics, 2013. 46(11): p. 1851-1858.

  • 23.
    Andersson, Stina
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Hultstrand Klint, Andrea
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    A smart poster? Visual design of marketing material for an exhibition of the concept Smart City2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Företaget HiQ i Norrköping vill skapa en bättre värld genom att förenkla och förbättra människors liv med hjälp av teknik. Konceptet Smart City handlar om utmaningar inom områden som energi, miljö och trafik som Norrköping kommun kommer att ställas inför i framtiden. HiQ anordnar i maj 2015 ett hackathon där studenter under några timmar ska komma fram till olika Smart City-lösningar. Dessa idéer kommer sedan presenteras i en utställning på Visualiseringscenter i Norrköping. För att dra besökare till utställningen krävs det att utställningen marknadsförs mot en intresserad och relevant målgrupp. Marknadsföringen till utställningen ska verka för att övertyga målgruppen att gå på utställningen. En affisch togs därför fram efter teorier och utvärderades sedan under sex kvalitativa intervjuer. Därefter transkriberades de insamlade data och analyserades med hjälp av meningskoncentrering.Studien syftar till att undersöka hur en affisch bör utformas visuellt för att locka målgruppen, Medieteknikstudenter vid Linköpings universitet, till utställningen. För att locka målgruppen till utställningen bör affischen innehålla fler visuella element i form av bilder, det vill säga illustrationer eller fotografier som är kopplade till konceptet och utställningen. Den textbaserade informationen bör tydligare förklara vad det är utställningen handlar om. Affischen bör utformas mer utmärkande om den ska bli ihågkommen. För att affischen som utformades i denna studie ska generera det förväntade intrycket krävs en del justeringar.

  • 24.
    Andersson, Thord
    et al.
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Läthén, Gunnar
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Lenz, Reiner
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Borga, Magnus
    Linköping University, Center for Medical Image Science and Visualization, CMIV. Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology.
    Modified Gradient Search for Level Set Based Image Segmentation2013In: IEEE Transactions on Image Processing, ISSN 1057-7149, E-ISSN 1941-0042, Vol. 22, no 2, 621-630 p.Article in journal (Refereed)
    Abstract [en]

    Level set methods are a popular way to solve the image segmentation problem. The solution contour is found by solving an optimization problem where a cost functional is minimized. Gradient descent methods are often used to solve this optimization problem since they are very easy to implement and applicable to general nonconvex functionals. They are, however, sensitive to local minima and often display slow convergence. Traditionally, cost functionals have been modified to avoid these problems. In this paper, we instead propose using two modified gradient descent methods, one using a momentum term and one based on resilient propagation. These methods are commonly used in the machine learning community. In a series of 2-D/3-D-experiments using real and synthetic data with ground truth, the modifications are shown to reduce the sensitivity for local optima and to increase the convergence rate. The parameter sensitivity is also investigated. The proposed methods are very simple modifications of the basic method, and are directly compatible with any type of level set implementation. Downloadable reference code with examples is available online.

  • 25.
    Andersson, Victor
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Björs, Matilda
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Internal communication of a brand - A comparative study within the municipality of Norrköping2014Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The municipality of Norrköping is a large organization with lots of different areas of expertise. To make sure that the values are the same throughout the organization is a heavy task but important if you want the brand to be communicated in the right way in all instances of the organization. An internal review of the employees opinions takes place every other year with the last one taking place in 2013. The results from the review made the municipality of Norrköping realise that they needed to increase their internal work with brand knowledge. The municipality of Norrköping took action and created a platform of communications called Let´s Create Norrköping. The problem they stand before now is that they're not sure if the employees have interpreted the information the correct way regarding the brand. This case study aims to investigate how the brand Norrköping is communicated throughout the plattform Let´s Create Norrköping and how the employees perceives the brand of the municipality of Norrköping.

    To answer the cause of the report a data collection has been made with interviews divided into two parts. The first part consists of an interview with Tina Vennerholm, brand developer at the communications department of the municipality of Norrköping. The main objective of this interviews was to conclude the main objectives of the platform Let´s Create Norrköping. The second part was conducted with five employees within the organization of the municipality of Norrköping. It was conducted to conclude their point of view of the platform Let´s Create Norrköping. Conclusions that can be drawn from the study include that the employees lack the presence of the representatives of the municipality of Norrköping at their working places. The employees have a positive opinion regarding the platform Let´s Create Norrköping although they have not received any internal information regarding the plattform. The reason to their positive opinions ought to be that they have been affected by external marketing regarding the plattform. This leads to the employees having a hard time with implementing the message of the platform in their work.

    Recommendations given to the municipality of Norrköping is to be visible at the various working places, to show the worker which people who are responsible for the communication at their workplace. to give the employees a personal connection to the source of the information that is given which makes it easier for the worker to accept and implement the information.

    The employees all have positive connections to the city of Norrköping. That is why the conductors of this study recommend that the municipality of Norrköping should make a connection to the city with the work that is made by the employees on all the different areas in the organization. This is to engage and motivate the employees and make them see and understand the connection between the city and the organization and the part that they play in it.

  • 26.
    Angelakis, Vangelis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Gundlegård, David
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Rydergren, Clas
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Rajna, Botond
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Vrotsou, Katerina
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Carlsson, Richard
    Ericsson Research, Services & Software.
    Forgeat, Julien
    Ericsson Research, Services & Software.
    Hu, Tracy H
    Ericsson Research, Services & Software.
    Liu, Evan L
    Ericsson Research, Services & Software.
    Moritz, Simon
    Ericsson Research, Services & Software.
    Zhao, Sky
    Ericsson Research, Services & Software.
    Zheng, Yaotian
    Ericsson Research, Services & Software.
    Mobility modeling for transport efficiency: Analysis of travel characteristics based on mobile phone data2013In: Netmob 2013: Mobile phone data for development / [ed] Vincent Blondel, 2013Conference paper (Refereed)
    Abstract [en]

    Signaling data from the cellular networks can provide a means of analyzing the efficiency of a deployed transportation system and assisting in the formulation of transport models to predict its future use. An approach based on this type of data can be especially appealing for transportation systems that need massive expansions, since it has the added benefit that no specialized equipment or installations are required, hence it can be very cost efficient.

    Within this context in this paper we describe how such obtained data can be processed and used in order to act as enablers for traditional transportation analysis models. We outline a layered, modular architectural framework that encompasses the entire process and present results from initial analysis of mobile phone call data in the context of mobility, transport and transport infrastructure. We finally introduce the Mobility Analytics Platform, developed by Ericsson Research, tailored for mobility analysis, and discuss techniques for analyzing transport supply and demand, and give indication on how cell phone use data can be used directly to analyze the status and use of the current transport infrastructure.

  • 27.
    Ankaräng, Nils
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Davidsson, Edvard
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Analys av arbetsplatsomkostnader2014Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Konkurrensen inom byggbranschen har ökat de senaste åren och byggföretagen tvingas att ta större kontroll över sina kostnader för att fortsatt kunna driva en lönsam verksamhet. Intäkterna är något som man inte har så stora möjligheter att påverka, då det är bostadsmarknaden i stort som styr hur mycket man kan få betalt för sina produkter och byggnader. Den egna kostnadskontrollen och omkostnaderna har blivit det stora fokusområdet, då det är via dem som man kan förbättra sina marginaler. Detta arbete har skrivits i samarbete med JM Bostad Stockholm som idag har ett stort fokus inom detta område. Då projekten ofta är unika i sig kan det vara svårt att jämföra projekten med varandra för att se vilka arbetsplatser som är kostnadseffektiva samt i vilka skeden som ett byggprojekt är mest krävande gällande arbetsplatsomkostnader. Syftet med denna studie har varit att undersöka arbetsplatsomkostnader för byggnadsprojekt med liknande utformning. Detta för att få fram var i projekten arbetsplatsomkostnaderna uppstår och härleda dem till skeden i den strukturerade tidplanen och se hur de varierar efter den strukturerade tidplan som det arbetas efter. Detta för att efter avslutad studie kunna göra kostnadseffektiva projektplaneringar för ett mer konkurrenskraftigt byggande.

  • 28.
    Antonsson, Andreas
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Kassander, Olivia
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Compelling interaction for large digital image archives2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Samhället idag sitter på ett stort kulturarv av bilder som nu digitaliserats i stora digitala bildarkiv. För att allmänheten ska få möjlighet att ta del av detta så har denna studie undersökt hur man kan skapa en interaktiv tjänst som ger åtkomst till ett stort antal bilder med en intresseväckande visuell upplevelse. För att besvara detta har en kvalitativ studie genomförts med en blandning av forskning genom design och fallstudie. Studiens har bestått av intervjuer med en intendent på Norrköpings stadsmuseum och fokusgrupper som besvarar målgruppens efterfrågan. Utifrån detta skapades designförslag som testades med hjälp av användbarhetstester och som därefter utvärderades genom en induktiv kvalitativ analys. Studiens resultat visar att skapandet av en interaktiv tjänst som ger åtkomst till ett stort antal bilder med en intresseväckande visuell upplevelse bör utgå från en tydlig och engagerande interaktion. Med bilder som får ta stor plats och med element som kan öka intresset i form av karta som visualliserar bildens position och tidslinje som ger möjlighet till filtrering.

  • 29.
    Appelgren, Caroline
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Olsson, Lisa
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Ett branschperspektiv: normbrytning och stereotyper i reklam2014Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    På grund av stor konkurrens är det svårt att skapa reklam som fångar uppmärksamhet. Det finns olika verktyg för nå igenom mediaflödet. I den här studien undersöks orsaker och konsekvenser till användning av normbrytande- och stereotypisk kommunikation. Konsekvenser har tidigare studerats ur ett beteendevetarperspektiv. Studierna visar att reklam påverkar samhällets normer. Marknadskommunikativa orsaker tas inte upp och därför behövs en analys som lyfter fram för- och nackdelar ur reklambranschens perspektiv. Det förklarar varför stereotyper används och ger branschens intryck av konsekvenserna i att bryta eller förstärka normer. Den här studien har gjorts för att öka medvetenheten hos yrkesverksamma kommunikatörer. Datainsamling har gjorts genom kvalitativa intervjuer med sju yrkesverksamma kommunikatörer. Två reklamfilmer användes som diskussionsunderlag vid intervjuerna. Intervjuerna övergick sedan i mer allmänna frågor kring stereotyper, normer och normbrytande, informanterna fick reflektera över upplevda orsaker och konsekvenser. Slutsatser som kunnat dras från studien är att både normbrytning och stereotyper kan vara ett sätt att synas i dagens mediaflöde. Reklam är väldigt kundstyrt eftersom det är beställaren som tar störst risker med sitt varumärke och sin investering. Kommunikatörerna anser att deras största ansvar är gentemot beställaren. Stereotyper anses vara den säkra vägen. De identifieras snabbt och mycket slipper förklaras. I snabb kommunikation tar de inte onödig uppmärksamhet från budskapet. En nackdel med stereotyper är att de är opersonliga. De sticker inte ut ur mängden och reklamen glöms snabbt bort. En ytterligare nackdel med stereotyper anses vara att de påverkar samhället genom att förstärka fördomar och könsroller. Normbrytande reklam sticker ut och blir ihågkommen, vilket är en stor konkurrensfördel. Det kan också vara ett verktyg för ett långsiktigt identitetsskapande som skapar en målgruppsgemenskap och ett starkt varumärke. Normbrytning kan även påverka samhället genom att öka acceptans. En oro kring konsekvenserna av normbrytning leder till en försiktighet, både hos byråer och beställare. Risken är att få dålig publicitet och skada varumärket om det görs på del sätt. Det kan också göra kommunikationen otydlig och överskugga företagets produkt. Majoriteten av informanterna finner normbrytande reklam sällan förekommande. De upplever att de yngre generationerna har en större öppenhet och att normbrytning därför är vanligare i reklam riktad till ungdomar.

  • 30.
    Arkstål, Axel
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Lidström, Kristofer
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Enkel vägvisning i en komplex miljö - Att hitta rätt på Linköpings Universitetssjukhus2014Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Att hitta rätt i den stora, komplexa miljön på Linköpings Universitetssjukhus är en utmaning. I nuläget finns skyltning och information i miljön men denna fungerar inte på ett tillräckligt bra sätt. Det är så pass bristande att man har guider vid entrén för att vägleda besökare rätt, något som är både opraktiskt och oekonomiskt. Syftet med denna designfallstudie var att utveckla ett wayshowingsystem för besökare på Linköpings Universitetssjukhus kring dess södra entré och i huvudbyggnaden. För att uppfylla syftet genomfördes ett antal kvalitativa intervjuer och observationer i miljön samt insamling av data från tidigare studier som gjorts i ämnet. Det slutliga resultatet är en kravlista för viktiga parametrar att ha i åtanke vid wayshowing på sjukhuset samt en skyltmanual baserad på kravlistan, med en detaljerad grund kring hur ett skyltsystem på sjukhuset ska se ut. Kravlistan ska kunna ligga till grund för all framtida skyltning på sjukhuset och samtliga krav är tänkta att alltid vara uppfyllda vid ny skyltning. Kraven innefattar framför allt att wayshowingen bör baseras på fysiska skyltar, det ska vara enkelt och tydligt att tolka samt att mängden information ska begränsas så mycket det går för att bli enklare att tyda. För att kunna implementera det nya skyltsystemet på hela sjukhuset behöver skyltmanualen kompletteras med detaljplanering för samtliga plan och byggnader, i nuläget är endast plan 9 och 10 i huvudbyggnaden färdiga för direkt implementation.

  • 31.
    Arvola, Mattias
    et al.
    Linköping University, Department of Computer and Information Science, MDALAB - Human Computer Interfaces. Linköping University, The Institute of Technology.
    Lundberg, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Holmlid, Stefan
    Linköping University, Department of Computer and Information Science, MDALAB - Human Computer Interfaces. Linköping University, The Institute of Technology.
    Analysis of precedent designs: Competitive analysis meets genre analysis2010In: NordiCHI '10 Proceedings of the 6th Nordic Conference on Human-Computer Interaction: Extending Boundaries / [ed] Hvannberg, E. Þ., Lárusdóttir, M. K., Blandford, A., Gulliksen, J., New York, NY, USA: Association for Computing Machinery (ACM), 2010, 23-31 p.Conference paper (Refereed)
    Abstract [en]

    Designers need to survey the competition and analyze precedent designs, but methods for that purpose have not been evaluated in earlier research. This paper makes a comparative evaluation between competitive analysis and genre analysis. A randomized between-group experiment was conducted where graphic design students were conducted one of the two analysis methods. There were 13 students in one group and 16 in the other. The results show that genre analysis produced more detailed descriptions of precedent designs, but its process was more difficult to understand. It is concluded that genre analysis can be integrated into competitive analysis, to make use of the strengths of both methods in the analysis of precedents.

  • 32.
    Arzani, Amirhossein
    et al.
    IIT.
    Dyverfeldt, Petter
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Ebbers, Tino
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Center for Medical Image Science and Visualization, CMIV.
    Shadden, Shawn C
    IIT.
    In Vivo Validation of Numerical Prediction for Turbulence Intensity in an Aortic Coarctation2012In: Annals of Biomedical Engineering, ISSN 0090-6964, E-ISSN 1573-9686, Vol. 40, no 4, 860-870 p.Article in journal (Refereed)
    Abstract [en]

    This paper compares numerical predictions of turbulence intensity with in vivo measurement. Magnetic resonance imaging (MRI) was carried out on a 60-year-old female with a restenosed aortic coarctation. Time-resolved three-directional phase-contrast (PC) MRI data was acquired to enable turbulence intensity estimation. A contrast-enhanced MR angiography (MRA) and a time-resolved 2D PCMRI measurement were also performed to acquire data needed to perform subsequent image-based computational fluid dynamics (CFD) modeling. A 3D model of the aortic coarctation and surrounding vasculature was constructed from the MRA data, and physiologic boundary conditions were modeled to match 2D PCMRI and pressure pulse measurements. Blood flow velocity data was subsequently obtained by numerical simulation. Turbulent kinetic energy (TKE) was computed from the resulting CFD data. Results indicate relative agreement (error a parts per thousand 10%) between the in vivo measurements and the CFD predictions of TKE. The discrepancies in modeled vs. measured TKE values were within expectations due to modeling and measurement errors.

  • 33.
    Attaullah, Muhammad
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    An LTE implementation based on a road traffic density model2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The increase in vehicular traffic has created new challenges in determining the behavior of performance of data and safety measures in traffic. Hence, traffic signals on intersection used as cost effective and time saving tools for traffic management in urban areas. But on the other hand the signalized intersections in congested urban areas are the key source of high traffic density and slow traffic. High traffic density causes the slow network traffic data rate between vehicle to vehicle and vehicle to infrastructure. To match up with the emerging technologies, LTE takes the lead with good packet delivery and versatile to changes in the network due to vehicular movements and density.

    This thesis is about analyzing of LTE implementation based on a road traffic density model. This thesis work is aimed to use probability distribution function to calculate density values and develop a real traffic scenario in LTE network using density values.

    In order to analyze the traffic behavior, Aimsun simulator software has been used to represent the real situation of traffic density on a model intersection. For a realistic traffic density model field measurement were used for collection of input data. After calibration and validation process, a close to realty results extracted and used a logistic curve of probability distribution function to find out the density situation on each part of intersection. Similar traffic scenarios were implemented on MATLAB based LTE system level simulator.

    Results were concluded with the whole traffic scenario of 90 seconds and calculating the throughput at every traffic signal time and section.

    It is quite evident from the results that LTE system adopts the change of traffic behavior with dynamic nature and allocates more bandwidth where it is more needed.

  • 34.
    Axelsson, Emil
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Costa, Jonathas
    NYU, NY 10003 USA.
    Silva, Claudio
    NYU, NY 10003 USA.
    Emmart, Carter
    Amer Museum Nat Hist, NY 10024 USA.
    Bock, Alexander
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Dynamic Scene Graph: Enabling Scaling, Positioning, and Navigation in the Universe2017In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 36, no 3, 459-468 p.Article in journal (Refereed)
    Abstract [en]

    In this work, we address the challenge of seamlessly visualizing astronomical data exhibiting huge scale differences in distance, size, and resolution. One of the difficulties is accurate, fast, and dynamic positioning and navigation to enable scaling over orders of magnitude, far beyond the precision of floating point arithmetic. To this end we propose a method that utilizes a dynamically assigned frame of reference to provide the highest possible numerical precision for all salient objects in a scene graph. This makes it possible to smoothly navigate and interactively render, for example, surface structures on Mars and the Milky Way simultaneously. Our work is based on an analysis of tracking and quantification of the propagation of precision errors through the computer graphics pipeline using interval arithmetic. Furthermore, we identify sources of precision degradation, leading to incorrect object positions in screen-space and z-fighting. Our proposed method operates without near and far planes while maintaining high depth precision through the use of floating point depth buffers. By providing interoperability with order-independent transparency algorithms, direct volume rendering, and stereoscopy, our approach is well suited for scientific visualization. We provide the mathematical background, a thorough description of the method, and a reference implementation.

    The full text will be freely available from 2018-07-01 14:42
  • 35.
    Axelsson, Emil
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Forsyth Rosin, Tomas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Spatial-temporal multi-modal visualization of volumetric simulation and in situ satellite data2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis describes the work done by two students from Link¨oping University during a five month stay at Community Coordinated Modelling Center (CCMC) at the National Aeronautics and Space Administration (NASA). The work includes the implementation of algorithms for rendering time-varying volume simulation data from space weather simulations hosted by the CCMC, as well as visualizing photo sequences taken by the Solar Dynamics Observatory (SDO) satellite orbiting Earth. Both these capabilities are added to the OpenSpace software to create a multi-modal visualization where scientists, as well as museum audiences, can observe the Sun’s activity and its effects on the heliosphere as a whole.

    Both the simulation data and the image sequence provided by the SDO are typically larger than what can be fitted into the main memory of modern computers, which requires the data to be streamed from disk. Due to limitations caused by disk and GPU bandwidth, it is not possible to stream the full resolution data sets in interactive frame rates.

    A multi-resolution bricking scheme is implemented to allow for interactive visualization of the large volumetric data sets. To decrease GPU memory usage and minimize data streaming, subvolumes are represented using different spatial and temporal resolution depending on their relative importance to the visual quality. By introducing the concept of a memory budget and a streaming budget, the algorithm allows the user to control how the limited memory and streaming resources are utilized.

    To decrease the amount of data to be streamed when visualizing image sequences from SDO, a simpler multi-resolution bricking scheme has been implemented. Spatial resolution of different subregions of the image is varied based on their visibility and projected size on the screen. Results show that the presented implementations enable interactive visualization of volumetric space weather data and satellite data. By varying the streaming budget and memory budget for a volumetric simulation, frame rate can be traded against visual quality.

  • 36.
    Axelsson, Viktor
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Automatisk segmentering och maskering av implantat i mammografibilder2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A report on my thesis developing an algorithm to automatically classify a mammogram image as containing an implant or not and segmenting and masking any present breast implant in the image.

  • 37.
    Axholt, Magnus
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Pinhole Camera Calibration in the Presence of Human Noise2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The research work presented in this thesis is concerned with the analysis of the human body as a calibration platform for estimation of a pinhole camera model used in Augmented Reality environments mediated through Optical See-Through Head-Mounted Display. Since the quality of the calibration ultimately depends on a subject’s ability to construct visual alignments, the research effort is initially centered around user studies investigating human-induced noise, such as postural sway and head aiming precision. Knowledge about subject behavior is then applied to a sensitivity analysis in which simulations are used to determine the impact of user noise on camera parameter estimation.

    Quantitative evaluation of the calibration procedure is challenging since the current state of the technology does not permit access to the user’s view and measurements in the image plane as seen by the user. In an attempt to circumvent this problem, researchers have previously placed a camera in the eye socket of a mannequin, and performed both calibration and evaluation using the auxiliary signal from the camera. However, such a method does not reflect the impact of human noise during the calibration stage, and the calibration is not transferable to a human as the eyepoint of the mannequin and the intended user may not coincide. The experiments performed in this thesis use human subjects for all stages of calibration and evaluation. Moreover, some of the measurable camera parameters are verified with an external reference, addressing not only calibration precision, but also accuracy.

    List of papers
    1. User Boresighting for AR Calibration: A Preliminary Analysis
    Open this publication in new window or tab >>User Boresighting for AR Calibration: A Preliminary Analysis
    2008 (English)In: Proceedings of the IEEE Virtual Reality Conference 2008, IEEE , 2008, 43-46 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    The precision with which users can maintain boresight alignment between visual targets at different depths is recorded for 24 subjects using two different boresight targets. Subjects' normal head stability is established using their Romberg coefficients. Weibull distributions are used to describe the probabilities of the magnitude of head positional errors and the three dimensional cloud of errors is displayed by orthogonal two dimensional density plots. These data will lead to an understanding of the limits of user introduced calibration error in augmented reality systems.

    Place, publisher, year, edition, pages
    IEEE, 2008
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-72053 (URN)10.1109/VR.2008.4480748 (DOI)978-1-4244-1971-5 (ISBN)
    Conference
    IEEE Virtual Reality Conference, 2008. VR '08, 8-12 March, Reno, Nevada, USA
    Available from: 2011-11-14 Created: 2011-11-14 Last updated: 2011-11-21Bibliographically approved
    2. User Boresight Calibration Precision for Large-Format Head-Up Displays
    Open this publication in new window or tab >>User Boresight Calibration Precision for Large-Format Head-Up Displays
    2008 (English)In: Proceedings of the 2008 ACM symposium on Virtual reality software and technology, New York, NY, USA: ACM , 2008, 141-148 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    The postural sway in 24 subjects performing a boresight calibration task on a large format head-up display is studied to estimate the impact of human limits on boresight calibration precision and ultimately on static registration errors. The dependent variables, accumulated sway path and omni-directional standard deviation, are analyzed for the calibration exercise and compared against control cases where subjects are quietly standing with eyes open and eyes closed. Findings show that postural stability significantly deteriorates during boresight calibration compared to when the subject is not occupied with a visual task. Analysis over time shows that the calibration error can be reduced by 39% if calibration measurements are recorded in a three second interval at approximately 15 seconds into the calibration session as opposed to an initial reading. Furthermore parameter optimization on experiment data suggests a Weibull distribution as a possible error description and estimation for omni-directional calibration precision. This paper extends previously published preliminary analyses and the conclusions are verified with experiment data that has been corrected for subject inverted pendulum compensatory head rotation by providing a better estimate of the position of the eye. With correction the statistical findings are reinforced.

    Place, publisher, year, edition, pages
    New York, NY, USA: ACM, 2008
    Keyword
    boresight, line of sight, calibration, postural sway, augmented reality
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-43489 (URN)10.1145/1450579.1450610 (DOI)73950 (Local ID)978-1-59593-951-7 (ISBN)73950 (Archive number)73950 (OAI)
    Conference
    15th ACM Symposium on Virtual Reality Software and Technology, Bordeaux, France October 27-29
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2011-11-14Bibliographically approved
    3. Visual Alignment Precision in Optical See - Through AR Displays: Implications for Potential Accuracy
    Open this publication in new window or tab >>Visual Alignment Precision in Optical See - Through AR Displays: Implications for Potential Accuracy
    2009 (English)In: Proceedings of the ACM/IEEE Virtual Reality International Conference, Association for Computing Machinery (ACM), 2009Conference paper, Published paper (Other academic)
    Abstract [en]

    The quality of visual registration achievable with anoptical see-through head mounted display (HMD)ultimately depends on the user’s targetingprecision. This paper presents design guidelines forcalibration procedures based on measurements ofusers’ head stability during visual alignment withreference targets. Targeting data was collected from12 standing subjects who aligned a head fixedcursor presented in a see-through HMD withbackground targets that varied in azimuth (0°, ±30°,±60°) and elevation (0°, ±10°). Their data showedthat: 1) Both position and orientation data will needto be used to establish calibrations based on nearbyreference targets since eliminating body swayeffects can improve calibration precision by a factorof 16 and eliminate apparent angular anisotropies.2) Compensation for body sway can speed thecalibration by removing the need to wait for thebody sway to abate, and 3) calibration precision canbe less than 2 arcmin even for head directionsrotated up to 60° with respect to the user’s torsoprovided body sway is corrected. Users ofAugmented Reality (AR) applications overlookinglarge distances may avoid the need to correct forbody sway by boresighting on markers at relativelylong distances, >> 10 m. These recommendationscontrast with those for heads up displays using realimages as discussed in previous papers.

    Place, publisher, year, edition, pages
    Association for Computing Machinery (ACM), 2009
    National Category
    Computer Engineering
    Identifiers
    urn:nbn:se:liu:diva-52848 (URN)
    Conference
    ACM/IEEE Virtual Reality International Conference, 2009
    Available from: 2010-01-12 Created: 2010-01-12 Last updated: 2013-11-05Bibliographically approved
    4. Visual Alignment Accuracy in Head Mounted Optical See-Through AR Displays: Distribution of Head Orientation Noise
    Open this publication in new window or tab >>Visual Alignment Accuracy in Head Mounted Optical See-Through AR Displays: Distribution of Head Orientation Noise
    2009 (English)In: Proceedings of the Human Factors and Ergonomics Society 53rd Annual Meeting 2009, San Antonio (TX), USA: Human Factors and Ergonomics Society , 2009, 2024-2028 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    The mitigation of registration errors is a central challenge for improving the usability of AugmentedReality systems. While the technical achievements within tracking and display technology continue toimprove the conditions for good registration, little research is directed towards understanding theuser’s visual alignment performance during the calibration process. This paper reports 12 standingsubjects’ visual alignment performance using an optical see-through head mounted display for viewingdirections varied in azimuth (0°, ±30°, ±60°) and elevation (0°, ±10°). Although viewing direction hasa statistically significant effect on the shape of the distribution, the effect is small and negligible forpractical purposes and can be approximated to a circular distribution with a standard deviation of 0.2°for all viewing directions studied in this paper. In addition to quantifying head aiming accuracy with ahead fixed cursor and illustrating the deteriorating accuracy of boresight calibration with increasingviewing direction extremity, the results are applicable for filter design determining the onset and end ofhead rotation.

    Place, publisher, year, edition, pages
    San Antonio (TX), USA: Human Factors and Ergonomics Society, 2009
    National Category
    Computer Engineering
    Identifiers
    urn:nbn:se:liu:diva-52854 (URN)10.1177/154193120905302710 (DOI)978-161567623-1 (ISBN)
    Conference
    53rd Human Factors and Ergonomics Society Annual Meeting 2009, HFES 2009; San Antonio, TX; United States
    Available from: 2010-01-12 Created: 2010-01-12 Last updated: 2014-09-04Bibliographically approved
    5. Optical See-Through Head Mounted Display: Direct Linear Transformation Calibration Robustness in the Presence of User Alignment Noise
    Open this publication in new window or tab >>Optical See-Through Head Mounted Display: Direct Linear Transformation Calibration Robustness in the Presence of User Alignment Noise
    Show others...
    2010 (English)In: Proceedings of the 54th Annual Meeting of the Human Factors and Ergonomics Society, 2010Conference paper, Published paper (Refereed)
    Abstract [en]

    The correct spatial registration between virtual and real objects in optical see-through augmented reality implies accurate estimates of the user’s eyepoint relative to the location and orientation of the display surface. A common approach is to estimate the display parameters through a calibration procedure involving a subjective alignment exercise. Human postural sway and targeting precision contribute to imprecise alignments, which in turn adversely affect the display parameter estimation resulting in registration errors between virtual and real objects. The technique commonly used has its origin incomputer vision, and calibrates stationary cameras using hundreds of correspondence points collected instantaneously in one video frame where precision is limited only by pixel quantization and image blur. Subsequently the input noise level is several order of magnitudes greater when a human operator manually collects correspondence points one by one. This paper investigates the effect of human alignment noise on view parameter estimation in an optical see-through head mounted display to determine how well astandard camera calibration method performs at greater noise levels than documented in computer vision literature. Through Monte-Carlo simulations we show that it is particularly difficult to estimate the user’s eyepoint in depth, but that a greater distribution of correspondence points in depth help mitigate the effects of human alignment noise.

    Keyword
    Head-mounted display, Calibration, Direct linear transform, Robustness
    National Category
    Control Engineering
    Identifiers
    urn:nbn:se:liu:diva-60435 (URN)9780945289371 (ISBN)
    Conference
    54th Annual Meeting of the Human Factors and Ergonomics Society, San Francisco, USA, 27 September-1 October, 2010
    Available from: 2010-10-13 Created: 2010-10-13 Last updated: 2015-09-22Bibliographically approved
    6. Parameter Estimation Variance of the Single Point Active Alignment Method in Optical See-Through Head Mounted Display Calibration
    Open this publication in new window or tab >>Parameter Estimation Variance of the Single Point Active Alignment Method in Optical See-Through Head Mounted Display Calibration
    Show others...
    2011 (English)In: Proceedings of the IEEE Virtual Reality Conference / [ed] Michitaka Hirose, Benjamin Lok, Aditi Majumder and Dieter Schmalstieg, Piscataway, NJ, USA: IEEE , 2011, 27-24 p.Conference paper, Published paper (Refereed)
    Abstract [en]

    The parameter estimation variance of the Single Point Active Alignment Method (SPAAM) is studied through an experiment where 11 subjects are instructed to create alignments using an Optical See-Through Head Mounted Display (OSTHMD) such that three separate correspondence point distributions are acquired. Modeling the OSTHMD and the subject's dominant eye as a pinhole camera, findings show that a correspondence point distribution well distributed along the user's line of sight yields less variant parameter estimates. The estimated eye point location is studied in particular detail. Thefindings of the experiment are complemented with simulated datawhich show that image plane orientation is sensitive to the numberof correspondence points. The simulated data also illustrates someinteresting properties on the numerical stability of the calibrationproblem as a function of alignment noise, number of correspondencepoints, and correspondence point distribution.

    Place, publisher, year, edition, pages
    Piscataway, NJ, USA: IEEE, 2011
    Series
    IEEE Virtual Reality Conference, ISSN 1087-8270
    Keyword
    single point active alignment method, camera resectioning, calibration, optical see-through head mounted display, augmented reality
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67233 (URN)10.1109/VR.2011.5759432 (DOI)000297260400004 ()978-1-4577-0037-8 (online), 978-1-4577-0039-2 (print) (ISBN)
    Conference
    IEEE Virtual Reality Conference, pages 27–34, Singapore, Republic of Singapore
    Available from: 2011-04-04 Created: 2011-04-04 Last updated: 2015-09-22Bibliographically approved
    7. Accuracy of Eyepoint Estimation in Optical See-Through Head-Mounted Displays Using the Single Point Active Alignment Method
    Open this publication in new window or tab >>Accuracy of Eyepoint Estimation in Optical See-Through Head-Mounted Displays Using the Single Point Active Alignment Method
    Show others...
    2011 (English)Conference paper, Published paper (Other academic)
    Abstract [en]

    This paper studies the accuracy of the estimated eyepoint of an Optical See-Through Head-Mounted Display (OST HMD) calibrated using the Single Point Active Alignment Method (SPAAM). Quantitative evaluation of calibration procedures for OST HMDs is complicated as it is currently not possible to share the subject’s view. Temporarily replacing the subject’s eye with a camera during the calibration or evaluation stage has been proposed, but the uncertainty of a correct eyepoint estimation remains. In the experiment reported in this paper, subjects were used for all stages of calibration and the results were verified with a 3D measurement device. The nine participants constructed 25 visual alignments per calibration after which the estimated pinhole camera model was decomposed into its intrinsic and extrinsic parameters using two common methods. Unique to this experiment, compared to previous evaluations, is the measurement device used to cup the subject’s eyeball. It measures the eyepoint location relative to the head tracker, thereby establishing the calibration accuracy of the estimated eyepoint location. As the results on accuracy are expressed as individual pinhole camera parameters, rather than a compounded registration error, this paper complements  previously published work on parameter variance as the former denotes bias and the latter represents noise. Results indicate that the calibrated eyepoint is on average 5 cm away from its measured location and exhibits a vertical bias which potentially causes dipvergence for stereoscopic vision for objects located further away than 5.6 m. Lastly, this paper closes with a discussion on the suitability of the traditional pinhole camera model for OST HMD calibration.

    Keyword
    Accuracy, Single Point Active Alignment Method, Visual Alignment, Calibration, Augmented Reality
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-72054 (URN)
    Conference
    IEEE Virtual Reality Conference 2012, Orange County (CA), USA
    Available from: 2011-11-14 Created: 2011-11-14 Last updated: 2015-09-22Bibliographically approved
  • 38.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Peterson, Stephen
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Ellis, Stephen R.
    Human Systems Integration Division, NASA Ames Research Center.
    User Boresighting for AR Calibration: A Preliminary Analysis2008In: Proceedings of the IEEE Virtual Reality Conference 2008, IEEE , 2008, 43-46 p.Conference paper (Refereed)
    Abstract [en]

    The precision with which users can maintain boresight alignment between visual targets at different depths is recorded for 24 subjects using two different boresight targets. Subjects' normal head stability is established using their Romberg coefficients. Weibull distributions are used to describe the probabilities of the magnitude of head positional errors and the three dimensional cloud of errors is displayed by orthogonal two dimensional density plots. These data will lead to an understanding of the limits of user introduced calibration error in augmented reality systems.

  • 39.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Skoglund, Martin A.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    O’Connell, Stephen D.
    Swedish Air Force Combat Simulation Center at the Swedish Defence Research Agency.
    Cooper, Matthew D.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Ellis, Stephen R.
    Human Systems Integration Division at NASA Ames Research Center.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Accuracy of Eyepoint Estimation in Optical See-Through Head-Mounted Displays Using the Single Point Active Alignment Method2011Conference paper (Other academic)
    Abstract [en]

    This paper studies the accuracy of the estimated eyepoint of an Optical See-Through Head-Mounted Display (OST HMD) calibrated using the Single Point Active Alignment Method (SPAAM). Quantitative evaluation of calibration procedures for OST HMDs is complicated as it is currently not possible to share the subject’s view. Temporarily replacing the subject’s eye with a camera during the calibration or evaluation stage has been proposed, but the uncertainty of a correct eyepoint estimation remains. In the experiment reported in this paper, subjects were used for all stages of calibration and the results were verified with a 3D measurement device. The nine participants constructed 25 visual alignments per calibration after which the estimated pinhole camera model was decomposed into its intrinsic and extrinsic parameters using two common methods. Unique to this experiment, compared to previous evaluations, is the measurement device used to cup the subject’s eyeball. It measures the eyepoint location relative to the head tracker, thereby establishing the calibration accuracy of the estimated eyepoint location. As the results on accuracy are expressed as individual pinhole camera parameters, rather than a compounded registration error, this paper complements  previously published work on parameter variance as the former denotes bias and the latter represents noise. Results indicate that the calibrated eyepoint is on average 5 cm away from its measured location and exhibits a vertical bias which potentially causes dipvergence for stereoscopic vision for objects located further away than 5.6 m. Lastly, this paper closes with a discussion on the suitability of the traditional pinhole camera model for OST HMD calibration.

  • 40.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Skoglund, Martin
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    O'Connell, Stephen
    Swedish Defence Research Agency.
    Cooper, Matthew
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Ellis, Stephen
    NASA Ames Research Center.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Parameter Estimation Variance of the Single Point Active Alignment Method in Optical See-Through Head Mounted Display Calibration2011In: Proceedings of the IEEE Virtual Reality Conference / [ed] Michitaka Hirose, Benjamin Lok, Aditi Majumder and Dieter Schmalstieg, Piscataway, NJ, USA: IEEE , 2011, 27-24 p.Conference paper (Refereed)
    Abstract [en]

    The parameter estimation variance of the Single Point Active Alignment Method (SPAAM) is studied through an experiment where 11 subjects are instructed to create alignments using an Optical See-Through Head Mounted Display (OSTHMD) such that three separate correspondence point distributions are acquired. Modeling the OSTHMD and the subject's dominant eye as a pinhole camera, findings show that a correspondence point distribution well distributed along the user's line of sight yields less variant parameter estimates. The estimated eye point location is studied in particular detail. Thefindings of the experiment are complemented with simulated datawhich show that image plane orientation is sensitive to the numberof correspondence points. The simulated data also illustrates someinteresting properties on the numerical stability of the calibrationproblem as a function of alignment noise, number of correspondencepoints, and correspondence point distribution.

  • 41.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Skoglund, Martin
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Peterson, Stephen
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Cooper, Matthew
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Schön, Thomas
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Gustafsson, Fredrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Ellis, Stephen
    NASA Ames Research Center, USA.
    Optical See-Through Head Mounted Display: Direct Linear Transformation Calibration Robustness in the Presence of User Alignment Noise2010In: Proceedings of the 54th Annual Meeting of the Human Factors and Ergonomics Society, 2010Conference paper (Refereed)
    Abstract [en]

    The correct spatial registration between virtual and real objects in optical see-through augmented reality implies accurate estimates of the user’s eyepoint relative to the location and orientation of the display surface. A common approach is to estimate the display parameters through a calibration procedure involving a subjective alignment exercise. Human postural sway and targeting precision contribute to imprecise alignments, which in turn adversely affect the display parameter estimation resulting in registration errors between virtual and real objects. The technique commonly used has its origin incomputer vision, and calibrates stationary cameras using hundreds of correspondence points collected instantaneously in one video frame where precision is limited only by pixel quantization and image blur. Subsequently the input noise level is several order of magnitudes greater when a human operator manually collects correspondence points one by one. This paper investigates the effect of human alignment noise on view parameter estimation in an optical see-through head mounted display to determine how well astandard camera calibration method performs at greater noise levels than documented in computer vision literature. Through Monte-Carlo simulations we show that it is particularly difficult to estimate the user’s eyepoint in depth, but that a greater distribution of correspondence points in depth help mitigate the effects of human alignment noise.

  • 42.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Skoglund, Martin
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Peterson, Stephen
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Cooper, Matthew
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Schön, Thomas
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Gustafsson, Fredrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Ellis, Stephen
    NASA Ames Research Center, USA.
    Optical See-Through Head Mounted Display: Direct Linear Transformation Calibration Robustness in the Presence of User Alignment Noise2010Report (Other academic)
    Abstract [en]

    The correct spatial registration between virtual and real objects in optical see-through augmented reality implies accurate estimates of the user’s eyepoint relative to the location and orientation of the display surface. A common approach is to estimate the display parameters through a calibration procedure involving a subjective alignment exercise. Human postural sway and targeting precision contribute to imprecise alignments, which in turn adversely affect the display parameter estimation resulting in registration errors between virtual and real objects. The technique commonly used has its origin incomputer vision, and calibrates stationary cameras using hundreds of correspondence points collected instantaneously in one video frame where precision is limited only by pixel quantization and image blur. Subsequently the input noise level is several order of magnitudes greater when a human operator manually collects correspondence points one by one. This paper investigates the effect of human alignment noise on view parameter estimation in an optical see-through head mounted display to determine how well astandard camera calibration method performs at greater noise levels than documented in computer vision literature. Through Monte-Carlo simulations we show that it is particularly difficult to estimate the user’s eyepoint in depth, but that a greater distribution of correspondence points in depth help mitigate the effects of human alignment noise.

  • 43.
    Backenhof, Albert
    Linköping University, Department of Science and Technology, Media and Information Technology.
    Automatic Generation of Collision Hulls for Polygonal Objects2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Physics in interactive environments, such as computer games, and simulations require well madeand accurate bounding volumes in order to act both realistically and fast. Today it is common to useeither inaccurate boxes or spheres as bounding volumes or to model the volume by hand. Thesemethods are either too inaccurate or require too much time to ever be able to be used in real-time,accurate virtual environments.This thesis presents a method to automatically generate collision hulls for both manifolds and nonmanifolds.This allows meshes to be used in a physical environment in just a few seconds and stillbeing able to behave realistically. The method performs Approximate Convex Decomposition byiteratively dividing the mesh into smaller, more convex parts. Every part is wrapped in a convexhull. Together the hulls make an accurate, but low cost, convex representation of the original mesh.The convex hulls are stored in a bounding volume hierarchy tree structure that enables fast testingfor collision with the mesh.

  • 44. Banissi, Ebad
    et al.
    Bertschi, StefanBurkhard, RemoCounsell, JohnDastbaz, MohammadEppler, MartinForsell, CamillaLinköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.Johansson, JimmyJern, MikaelGrinstein, GeorgeMarchese, FrancisMaple, CarstenLaing, RichardCvek, UrsakaTruschl, MarjanStuart, LizUrsun, AnnaWyeld, Theodor
    Information Visualization2010Conference proceedings (editor) (Other academic)
  • 45. Banissi, Ebad
    et al.
    Bertschi, StefanBurkhard, RemoCvek, UrskaEppler, MartinForsell, CamillaLinköping University, Department of Science and Technology, Media and Information Technology.Grinstein, GeorgesJohansson, JimmyLinköping University, Department of Science and Technology, Media and Information Technology.Kenderdine, SarahMarchese, Francis T.Maple, CarstenTrutschl, MarjamSarfraz, MuhammadStuart, LizUrsyn, AnnaWyeld, Theodor G.
    Information Visualization2011Conference proceedings (editor) (Refereed)
  • 46.
    Baravdish, George
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Svensson, Olof
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Sofya, Faten
    Mosul University, Mosul, Iraq.
    PDE-SVD Based Audio Denoising2012In: Proceedings of the 5th International Symposium on Communications Control and Signal Processing (ISCCSP), 2012, Piscataway, NJ, USA: IEEE , 2012, 1-6 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we present a new method for denoising audio signals. The method is based on the Singular Value Decomposition (SVD) of the frame matrix representing the signal inthe Overlap Add decomposition. Denoising is performed by modifying both the singular values, using a tapering model, and the singular vectors of the representation, using a nonlinear PDE method. The performance of the method is evaluated and compared with denoising obtained by filtering.

  • 47.
    Bengtsson, Martin
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Ågren, Emil
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Image enhancement of license plates in images using Super Resolution2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Bildgruppen på enheten för dokument och informationsteknik hos SKL har ett behov av att kunna förbättra bilder med extremt låg upplösning. Detta bildmaterial kan komma från diverse övervakningskameror där det intressanta objektet endast utgör en väldigt liten del, i detta fall registreringsskyltar på förbipasserande bilar. Att skapa en högupplöst bild av en registreringsskylt utav ett fåtal lågupplösta bilder är ett välkänt problem med ett flertal förslag på metoder och lösningar. I denna rapport kommer vi att undersöka vilka metoder som passar bäst vid bildförbättring av registreringsskyltar. Vi kommer även att skapa ett användargränssnitt där man kan läsa in en bild och välja mellan att automatiskt hitta registreringsskylten i bilden eller att manuellt klippa ut den. Efter att man erhållit en bild innehållandes endast registreringsskylten ska de olika implementerade bildförbättringsmetoderna kunna användas. Slutligen diskuteras vilka för- och nackdelar de respektive metoderna har. Förslag på eventuella förbättringar och hur man kan utveckla dessa metoder vidare presenteras därtill.

  • 48.
    Bergman, Johan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Larsén, Henrik
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Terminal Gothenburg North - A posssible dry port?2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Green Cargo driver idag ett antal terminaler i Sverige i syfte att främja transporter på järnväg och ser möjligheter i att utveckla en av sina terminaler i Göteborg, Göteborg Norra, till en så kallad dry port, alltså en intermodal terminal i inlandet. Detta gav upphov till projektet Terminal Göteborg Norra – en möjlig dry port? med målet att undersöka potentialen och omställningarna med att utveckla befintligt kunderbjudande på Göteborg Norra genom att utreda konceptet dry port samt undersöka efterfrågan på marknaden. Syftet med en dry port är att fungera som en förlängning av hamnen och bör enligt forskare erbjuda samma servicetjänster som en hamn, det vill säga förtullning, säker lagring av både lastade och tomma containrar samt underhåll och städning av containrar. En dry port kan ses som ett bra komplement till hamnar som ligger inne i städer och har problem med begränsade utrymmen i hamnområdet och svårt att expandera då ytan inte längre räcker till. Dessutom kan man minska utsläppen av CO2 genom att få mer gods transporterat på järnvägen. Att utveckla Göteborg Norra, som Green Cargo idag driver i egen regi, skulle innebära att befintliga tjänster behöver kompletteras med de tjänster som fullbordar en dry port. Projektet resulterade i en utredning med potentiella intäkter och kostnader som förväntas uppstå vid ett utvecklande av Göteborg Norra till en dry port. Det visade sig att kostnaderna med att utveckla Göteborg Norra till en dry port är fullt möjliga att tjäna in inom den bestämda tidsramen på två år. Trots det så anser projektet att det finns många delar i utvecklandet som talar emot ett fulländat dry port koncept på Göteborg Norra. Då projektet anser att terminalens läge inte är optimalt för en dry port och att det finns begränsade lagringmöjligheter, oklarheter gällande tulltjänster samt att hamnen inte visar något intresse för att utnyttja tjänsten så är det svårt att motivera omställningen till en fulländad dry port. Däremot finns det en del i dry port konceptet som projektet ser positivt till och det skulle innebära att Göteborg Norra tar emot lastade containrar för transport till hamnen. Då projektets marknadsundersökning visade att många speditörer anser att det är problem med långa köer för att hämta och lämna gods i Göteborgs hamn så skulle Green Cargo kunna erbjuda en tjänst där dessa kunder kan åka till Göteborg Norra och lämna eller hämta sitt gods. Detta under förutsättning att Green Cargo kan erbjuda en billigare lösning och att det inte uppstår köer i trafiken runt terminalen. Klarar Green Cargo detta har de ett bra argument som borde locka både speditörer och Göteborgs hamn att nappa på lösningen.

  • 49.
    Bergström, Simon
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Ivarsson, Oscar
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Automation of a Data Analysis Pipeline for High-content Screening Data2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    High-content screening is a part of the drug discovery pipeline dealing with the identification of substances that affect cells in a desired manner. Biological assays with a large set of compounds are developed and screened and the output is generated with a multidimensional structure. Data analysis is performed manually by an expert with a set of tools and this is considered to be too time consuming and unmanageable when the amount of data grows large. This thesis therefore investigates and proposes a way of automating the data analysis phase through a set of machine learning algorithms. The resulting implementation is a cloud based application that can support the user with the selection of which features that are relevant for further analysis. It also provides techniques for automated processing of the dataset and training of classification models which can be utilised for predicting sample labels. An investigation of the workflow for analysing data was conducted before this thesis. It resulted in a pipeline that maps the different tools and software to what goal they fulfil and which purpose they have for the user. This pipeline was then compared with a similar pipeline but with the implemented application included. This comparison demonstrates clear advantages in contrast to previous methodologies in that the application will provide support to work in a more automated way of performing data analysis.

  • 50.
    Berntsson, Robin
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Photometric stereo for eye tracking imagery2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goal of this work is to examine the possibility of surface reconstruction from the images produced by the Tobii H5 eye tracker. It starts of by examining classic photometric stereo and its limitations under the illuminator configuration of the eye tracker. It then proceeds to investigate two alternative solutions: photometric stereo under the assumption that the albedo is known and a method that uses the images from the eye tracker as a guide to mold a reference model into the users face. In the second method the pose of the reference model is estimated by minimizing a photometric error under the assumption that the face is Lambertian, using particle swarm optimization. The position of the generic 3D model is then used in an attempt to mold its shape into the face of the user using shape-from-shading.

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