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  • 151.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Ahreberg, L
    Distributed Rendering in Heterogeneous Display Environments: A Functional Framework Design and Performan Assessment2002In: Proceedings of the Annual SIGRAD Conference, 2002, p. 23-28Conference paper (Other academic)
  • 152.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Forsberg, Ann-Kristin
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    A collaborative visualization environment for natural interaction with architectural content2009In: Proceedings of the 3rd ISPRS International Workshop 3D-ARCH 2009: "3D Virtual Reconstruction and Visualization of Complex Architectures" / [ed] Fabio Remondino, Sabry El-Hakim, Lorenzo Gonzo, 2009, p. XXXVIII-5/W1-Conference paper (Refereed)
  • 153.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Forsberg, Ann-Kristin
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Designing Efficient Visualizations for Applications in the Paper and Pulp Industry2009In: Proceedings of IADIS Applied Computing 2009, Rome, November 19-21 / [ed] Hans Weghorn and Pedro Isaías, 2009Conference paper (Refereed)
  • 154.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Forsberg, Ann-Kristin
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    On the Applicability of Direct and Indirect Input in Table-Top and Vertical Displays2009In: Proceedings of IADIS Applied Computing 2009, Rome, November 19-21 / [ed] Hans Weghorn and Pedro Isaías, 2009Conference paper (Refereed)
  • 155.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Forsberg, Ann-Kristin
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Wesslén, Daniel
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Enhanced Visualizations of Thermographic Data in Process Industry2006In: EuroVis 06 / [ed] Beatriz Sousa Santos and Thomas Ertl and Kenneth I. Joy, Eurographics Association , 2006, p. 307-314Conference paper (Other academic)
    Abstract [en]

    In this paper, we describe an improved method for visualization of thermographic data in the paper and pulp proc-ess industry. We present an application that allows process operators to freely choose how absolute temperatures and time varying changes of thermographic scans should be mapped to colors and/or 3D shapes. Of the possible combinations, we selected two different forms of 3D visualizations and an existing conventional 2D map visualiza-tion. We then evaluated these visualization forms with regard to their effectiveness in experimental field studies. The field tests were carried out to measure the operators’ performance in early detection of insulation damages on lime kilns. The results we obtained from the study show that the two new forms of 3D visualization lead to a reduc-tion of the detection times by about two-thirds and one-third, respectively, when compared to the conventional 2D map representation. Since lime kiln monitoring is based on the rather generic method of continuous thermographic imaging, we suggest that these results also hold for the control and surveillance of other processes.

  • 156.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Lindkvist, M
    Simulation based collaborative experiments for interactive learning in virtual classroom environments2001In: Proceedings of the 2nd European Conference on e-learning WBLE, 2001, p. 347-355Conference paper (Other academic)
  • 157.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Lindkvist, M
    Lars Winkler, Pettersson
    Interactive virtual mummy dissections in a historical anatomic theatre2003In: Proceedings of VAST2003: 4th International Symposium on Virtual Reality: Archeology and Intelligent Cultural Heritage, 2003Conference paper (Other academic)
    Abstract [en]

    This paper presents an interactive projection-based application for visual exploration of virtual mummies. It is part of an exposition on the Cultural Heritage of the Egyptian Mummies in the Museum Gustavianum, in Uppsala. We describe a general-purpose projection metaphor for correctly presenting virtual 3D images on the dissection table of a historical anatomic theatre. This method allows for dynamic offaxis perspective viewing situations as well as it provides keystone correction for excessive projection angles as necessitated by the specific installation environment. For the application to reach out beyond the scope of the exhibition, we developed an adaptive image-based rendering approach that scales with the performance of the rendering host. Based on dynamic mesh simplification of the 3D mummy model, it automatically performs re-projections of texture images in order to maintain correct visual results. For interaction purposes with a digitiser tablet we present a means of stroke-based input that provides ease of use to non-expert visitors of the exhibition.

  • 158.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Nivfors, Anders
    Efficient rendering of multiple refractions and reflections in natural objects2006In: Proceedings of the Annual SIGRAD Conference, 2006, p. 1-6Conference paper (Other academic)
  • 159.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Nivfors, Anders
    Real-time rendering of ice2007In: Computer graphics and imaging (CGIM 2007): proceedings of 9th IASTED International conference on computer graphics and imaging - CGIM : February 13-15, 2007, Innsbruck, Austria, 2007, p. 60-66Conference paper (Other academic)
  • 160.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Wagner, I V
    Koch, S
    Schneider, W
    Oral Implant Treatment Planning in a Virtual Reality Environment1998In: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, Vol. 57, no 1-2, p. 95-103Article in journal (Refereed)
    Abstract [en]

    A system for three-dimensional oral implant treatment planning is presented. Virtual reality technologies are used in order to improve the human image interpretation and planning performance. The methods described are based on computer tomography (CT) data of the mandible and of the maxilla. A novel approach to volume rendering and voxel based modelling of implants is introduced which allows interactive three-dimensional manipulation of the anatomic model and real-time manipulation of virtual implants. A spline-based reconstruction method is described to assess the implant site in a clinically oriented view with regard to bone structures and angulation. Two parameters are deduced which represent the bone properties at the surface of implants. While an implant is navigated with six degrees of freedom, these parameters are acoustically rendered which is a novel approach to exploration of spatial bone properties in a CT data set.

  • 161.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Wagner, IV
    Schneider, W
    Design of a 3D workbench interface for training in dental implantology1998In: MEDINFO 98: proceedings of the 9th World Congress on Medical Informatics / [ed] Jean-Raoul Scherrer, 1998, p. 907-911Conference paper (Other academic)
  • 162.
    Seipel, Stefan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Winkler Pettersson, Lars
    Informationsteknologi, Uppsala universitet.
    PixelActiveSurface: A Tabletop Rear-Projection Display for Collaboration with Pixel-Accurate Interaction2007Report (Other academic)
  • 163.
    Stanze, Erik
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Carlsson, Roger
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Alternativ till Oracle utifrån Lantmäteriets förhållanden2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Lantmäteriet i Gävle är ett företag som hanterar mycket stora datamängder i databaser och det är därför av stor vikt att de har ett väl fungerande databashanteringssystem. De använder sig av databashanteringssystemet Oracle, men intresse för alternativ finns. Lantmäteriet önskade därför en rapport som jämför deras nuvarande databashanteringssystem Oracle 10.2.0.3 med möjliga alternativ. De databashanteringssystem som i denna rapport jämfördes med Oracle är Microsoft SQL Server 2005 och MySQL 5.1. Aspekter som studerades är prestanda, kostnad, säkerhet, kompatibilitet, tillgänglighet och support. Detta skedde genom en informationsinsamling och testning av de olika databashanteringssystemen. Under de förhållanden testerna genomfördes visade det sig att Microsoft SQL Server 2005 är ett starkt alternativ till Oracle 10.2.0.3. MySQL 5.1 kan vara ett alternativ om man inte ställer allt för höga krav på prestanda och är intresserad av Open Source.

  • 164. Söderström, E
    et al.
    Haykowska, M
    Johannesson, P
    Wangler, B
    Zdravkovic, Jelena
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Serviam projekt: Mönsterkatalog2005Report (Other academic)
  • 165. Tarvainen, O
    et al.
    Markkola, A M
    Ahonen-Jonnarth, Ulla
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Jumpponen, A
    Strömmer, R
    Changes in Ectomycorrhizal Colonization and Root Peroxidase Activity in Pinus sylvestris Nursery Seedlings Planted in Forest Humus2004In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 19, no 5, p. 400-408Article in journal (Refereed)
    Abstract [en]

    Plant biomass, root colonization by ectomycorrhizal (ECM) fungi and root peroxidase (POD) activity were monitored in Scots pine (Pinus sylvestris L.) nursery seedlings during the first growing season after planting (after 4, 8 and 16 weeks, in July, August and October, respectively) in forest humus in outdoor open-top chambers with gaseous atmospheric pollutants (combinations of low levels of ozone, sulfur dioxide and nitrogen oxides). The number of ECM morphotypes as well as root biomass increased towards the end of the growing season, while root POD activity decreased. Fungal biomass estimated as ergosterol concentration peaked in August, 8 weeks after planting. The seedling growth, mycorrhizal status and POD activity in the roots were not affected by the gaseous pollutants.

  • 166.
    Wallin, Jonas
    University of Gävle. University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Jämförelse av animationslager och trax-editor2009Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Redan under stenåldern fanns illustrationer föreställande djur med ben som pekade åt alla möjliga håll för att ge intrycket av rörelse. Metoden för animering har sen dess utvecklats radikalt och blivit väldigt stor del av vår vardag. Att animationer blivit mer lättillverkade och billigare att producera har utökat användningsområdet betydligt. Syftet med här arbetet är att ge ökad förståelse för hur man animerar i Maya Det tar upp vad som gör en animering bra och vilka metoder animerare använder sig av när de framställer 3D animation. Arbetet är inriktat på framförallt två stycken olika verktyg i Maya som används vid animation, Trax-editorn och animationslager. En komparativ analys har gjorts av båda dessa verktyg. Animationslager är en väldigt ny funktion och det har därför inte gjorts någon liknande undersökning tidigare. Arbetet beskriver processen för två olika animationer som gjorts med hjälp av trax-editorn och animationslager. Slutsatsen av dessa test var att de ger animeraren möjligheten att snabbt ändra animationer väsentligt på ett väldigt smidigt sätt. Båda verktygen visade sig vara väldigt lika. Den största upptäckten var att animering går att utföra lika bra utan hjälp av animationslager och trax-editorn.

  • 167.
    Wedin, Tommy
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Fantasy War Game: Spelmotor i PHP2009Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Fantasy War Game är en spelmotor gjort i PHP med inslag av Java. Själva striden är uppbyggd med objektorienterad programmeringsmetodik. Spelet är ett textbaserat rollspel i high fantasy-miljö. Sidan är ett interaktivt konfliktspel där spelarna kan utveckla sitt gäng, slåss mot monster eller andra spelare.

  • 168.
    Wedman, Ingemar
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för naturvetenskap.
    Stoor, Markus
    Carling, Eva
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Djuvfeldt, Gunilla
    Holmström, Pernilla
    Linder, Johanna
    Validering av kunskaper och kompetens2007Report (Other academic)
  • 169.
    Wesslén, Daniel
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Seipel, Stefan
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    GPU-assisted Surface Reconstruction and Motion Analysis from Range Scanner Data2004In: Proceedings of the Annual SIGRAD Conference, 2004, p. 51-52Conference paper (Other academic)
  • 170.
    Wesslén, Daniel
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Seipel, Stefan
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Real-time visualization of animated trees2005In: The Visual Computer, ISSN 0178-2789, E-ISSN 1432-2315, Vol. 21, no 6, p. 397-405Article in journal (Refereed)
    Abstract [en]

    Realistic visualization of plants and trees has recently received increased interest in various fields of applications. Limited computational power and the extreme complexity of botanical structures have called for tradeoffs between interactivity and realism. In this paper we present methods for the creation and real-time visualization of animated trees. In contrast to other previous research, our work is geared toward near-field visualization of highly detailed areas of forestry scenes with animation. We describe methods for rendering and shading of trees by utilizing the programmable hardware of consumer-grade graphics cards. We then describe a straightforward technique for animation of swaying stems and fluttering foliage that can be executed locally on a graphics processor. Our results show that highly detailed tree structures can be visualized at real-time frame rates and that animation of plant structures can be accomplished without sacrificing performance.

  • 171.
    Wesslén, Daniel
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Seipel, Stefan
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    The Virtual Forest (Poster)2004In: Proceedings of the Annual SIGRAD Conference, 2004, p. 61-61Conference paper (Other academic)
  • 172.
    Willstedt, Martin
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Litzell, Peter
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Utveckling av databassystem för Sjölins Smide2009Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Ett genomtänkt databassystem består av en väl utformad databas samt lättanvänt användargränsnitt. Brister i dessa punkter kan orsaka irritation och illvilja mot användning av systemet. Syftet med detta uppdrag var att åtgärda dessa brister för vår uppdragsgivare och skräddarsy en lösning utifrån användarnas perspektiv. En webbaserad lösning valdes för att främja mobilitet och tillgänglighet bland företagets anställda. Resultatet blev ett system som bättre stödjer användarna i vardagliga arbetsuppgifter.

  • 173.
    Winkler Pettersson, Lars
    et al.
    Informationsteknologi, Uppsala universitet.
    Seipel, Stefan
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Collaborative pixel-accurate interaction with PixelActiveSurface2007In: Extended Abstracts 2007, 2007Conference paper (Refereed)
  • 174.
    Ytterström, Christian
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Virtuell modulbaserad Fotbollsarena2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna uppsats syftar att undersöka samt ta fram en modell över ett system i PC Spelet Power Soccer där användaren själv kan designa sin egen hemmaarena med hjälp av ett webbgränssnitt. Arbetet inleds med en begränsad enkätundersökning där användare fick bedöma betydelsegraden av olika inslag i en fotbollsarena. Efter resultatet av denna enkät togs en modell fram i Autodesk Maya med ett modulbaserat system. Detta kompletteras med ett webbgränssnitt där användaren väljer vilka delar som han vill placera på de olika platser som erbjuds. Till sist beskrivs själva modulen och hur den ska fungera.

  • 175. Zander, Carol
    et al.
    Boustedt, Jonas
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Eckerdal, Anna
    McCartney, Robert
    Moström, Jan-Erik
    Ratcliffe, Mark
    Sanders, Kate
    Threshold concepts in computer science: a multi-national empirical investigation2008In: Threshold concepts within the disciplines / [ed] Ray Land, Jan H. F. Meyer, Jan Smith, Rotterdam: Sense , 2008, p. 105-118Chapter in book (Other academic)
    Abstract [en]

    This chapter describes an ongoing project aimed at empirically identifying threshold concepts in computer science. In a multi-national, multi-institutional study, we have gathered data from both educators and students. The paper outlines our experiences with various experimental techniques, issues raised, and results to date.

  • 176.
    Zander, Carol
    et al.
    University of Washington, Bothell, Bothell, WA, USA.
    Boustedt, Jonas
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    McCartney, Robert
    University of Connecticut, Storrs, CT, USA.
    Moström, Jan-Erik
    Umeå University, Umeå, Sweden.
    Sanders, Kate
    Rhode Island College, Providence, RI, USA.
    Thomas, Lynda
    Aberystwyth University, Aberystwyth, Wales Uk.
    Student transformations: are they computer scientists yet?2009In: ICER '09: Proceedings of the fifth international workshop on Computing education research, New York: ACM , 2009, p. 129-140Conference paper (Refereed)
    Abstract [en]

    We examine the changes in the ways computing students view their field as they learn, as reported by the students themselves in short written biographies. In many ways, these changes result in students thinking and acting more like computer scientists and identifying more with the computing community. Most of the changes are associated with programming and software engineering, rather than theoretical computer science, however.

  • 177.
    Zdravkovic, Jelena
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Adjustment of Process Transactional Properties for Flexible Workflow Management2003In: 15th Conference on Advanced SE (CAiSE03), CAiSE FORUM, CEUR , 2003Conference paper (Other academic)
  • 178.
    Zdravkovic, Jelena
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Concepts of Flexibility for Efficient Integration of B2B Processes2004In: Proceedings of the International Workshop on Modelling Inter-Organizational Systems (MIOS’04) / [ed] Meersman, R, 2004, p. 431-443Conference paper (Refereed)
    Abstract [en]

    Business-to-Business (B2B) e-commerce is emerging as trading parties are attempting to integrate electronically, to automate exchange of their services. To be able to collaborate, enterprise processes must expose compatible public behavior. It is a common need for a company to collaborate a business with many partners. A problem is that, even agreeing on information to be exchanged, the partners usually expose different requirements for protocol and logic of interactions. Therefore, it becomes necessary for companies to redesign process models to accommodate to a new partner. As the result, the company must engage considerable resources for designing and verifying new process specifications, as well as for maintaining them. In this paper, we propose a framework for flexible modeling of enterprise processes, to support a larger scale of B2B integrations. The proposal is based on a set of concepts of flexibility that enable partial process specifications, depicting thus a wider scope of business scenarios that a company is willing to conform in a B2B context. The complete process specification is made after B2B parties agree on a strict public protocol and enforced by runtime transformations. The proposed framework for flexible process modeling is aimed to speed up integration of partner processes as it increases ability for process matching without requiring changes in their design.

  • 179.
    Zdravkovic, Jelena
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Process Integration for the Extended Enterprise2006Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    In many industries today, the speed and costs with which new products are delivered to customers provide the basis for competitive advantage. Electronic business (e-business) is a concept that shortens the “time to market” and enables transacting at lower costs. Currently, one of the main limitations in the exploitation of e-business is the lack of efficient Information System (IS) integration, both in intra- and cross-enterprise environments. Intra-enterprise integration is complex, as the business needs and the underlying information systems do not evolve in accordance. In the cross-enterprise context, transparent system integration is hardly achievable due to the incompatibility of the services of the involved partners. This means that the future success of the integration depends heavily on the possibilities offered in terms of interoperability among the involved enterprises. The Business Process Management (BPM) discipline addresses this challenge, as processes have been recognized as key mechanisms through which most intra- and cross-enterprise interactions take place. The development of methods for successful integration of process models is one of the essential issues for the use of the BPM approach in the application and evolution of e-business.

    In this thesis, we address two topics in the area of business process management: 1) intra-enterprise process integration which concerns alignment between the internal business processes and information systems enclosed in the form of software services and 2) cross-enterprise integration which concerns coordination of the internal business processes of an enterprise with the processes of its suppliers, intermediaries, or customers. The goal of the thesis is to add theoretical and applicable knowledge to the field of business process management by using the proposed approaches for improvement of process integration in intra- and cross-enterprise contexts.

  • 180.
    Zdravkovic, Jelena
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Henkel, M
    Flexible Realisations of Business Processes Using Existing Services2006In: Proceedings of the 8th International Conference on Enterprise Information Systems (ICEIS 06), 2006, p. 165-172Conference paper (Other academic)
    Abstract [en]

    When realizing executable business process models, in most situations process specifications collide with specific properties of existing services. In this paper we propose an approach for relaxation of the business process specification to enable flexible integration between the process and existing services. The approach is based on the notion of visibility, which allows a categorized relaxation of the process specification by not requiring every process state to be distinguished after the process is realised with existing services. The categories of visibility presented in this paper are applied by indicating flexible elements in the process design phase. The presented approach stimulates the alignment between business processes and existing services, facilitating a larger scale of transparent process realisations.

  • 181.
    Zdravkovic, Jelena
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Henkel, Martin
    Flexible Integration of Business and Technology Using Service-Based Processes2005In: The Proceedings of the 6th BPMDS Workshop. CAiSE’05 Workshops, 2005Conference paper (Other academic)
    Abstract [en]

    When designing executable enterprise processes the assumption of a transparent integration with existing systems is unrealistic. These systems, represented by software services, may impose various constraints. Using a process description framework, in this paper we examine how the design of executable business processes is affected by technical issues. Furthermore, we examine rules to which system designers should adhere to when designing services, to enable a larger scope of “as-is” realizations of business processes.

  • 182.
    Zdravkovic, Jelena
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Henkel, Martin
    Johannesson, Paul
    Moving from Business to Technology with Service-Based Processes2005In: IEEE Internet Computing, ISSN 1089-7801, E-ISSN 1941-0131, Vol. 9, no 3, p. 73-81Article in journal (Other academic)
    Abstract [en]

    In most organizations, business process realizations must be aligned with existing systems, which can impose specific requirements. Currently, however, there is no way to track the alignment between business processes and corresponding technical implementations. The authors' proposed framework offers a systematic way to classify and assess technical realizations of business processes.

  • 183.
    Zdravkovic, Jelena
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Johannesson, P
    Cooperation of Processes through Message Level Agreement2004In: Proceedings of the 16th International Conference on Advanced Information Systems Engineering (CAiSE’04), 2004, p. 564-579Conference paper (Other academic)
  • 184.
    Zdravkovic, Jelena
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Kabilan, Vandana
    Enabling Business Process Interoperability Using Contract Workflow Models2005In: The Proceedings of the 13th International Conference on Cooperative Information Systems (CooPIS’05), 2005, p. 77-93Conference paper (Other academic)
    Abstract [en]

    Business transactions are governed by legally established contracts. Contractual obligations are to be fulfilled by executing business processes of the involved parties. To enable this, contract terms and conditions need to be semantically mapped to process concepts and then analyzed for compliance with existing process models. To solve the problem, we propose a methodology that, using a layered contract ontology, deduces contract requirements into a high-level process description named Contract Workflow Model (CWM). By applying a set of transformation rules, the CWM is then compared for compliance with existing, executable process models. By the use of its concepts, the methodology enables comprehensive identification and evolution of requirements for interoperability of processes of the contracting parties.

  • 185.
    Zdravkovic, Jelena
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Åhlén, Julia
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Modeling Image Processing Tasks As Flexible Workflows for Improved Quality of Service2004In: The IADIS Applied Computing / [ed] Nuno Guimarães and Pedro Isaías, 2004, p. 363-370Conference paper (Other academic)
    Abstract [en]

    Processing of nontrivial images is a difficult task performed throughout a set of ordered steps. Besides the basic functionality that a process must satisfy, quality of service goals are to be met. Images should be processed within a certain time and a certain quality should be attained. To manage image-processing tasks in the optimal way, the process goals must be defined explicitly and their fulfillment has be controlled. Modeling image-processing tasks with workflows would enable control of the fulfillment of goals. In addition, by introducing flexible semantics in the workflow, the process could be executed along optimal execution alternatives. In this paper, we propose an approach to model the class of image processing tasks with workflows that would, based on the extended semantics, allow for flexibility in the process execution toward optimal goals fulfillment.

  • 186.
    Zdravkovic, Vladan
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Carling, Eva
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Hast, Anders
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap. Uppsala University .
    Seipel, Stefan
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap. Uppsala University .
    University of Gävle prepares students for entry into industry2002In: Computer graphics, ISSN 0097-8930, E-ISSN 1558-4569, Vol. 36, no 2, p. 27-32Article in journal (Refereed)
  • 187.
    Åhlén, Julia
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Colour Correction of Underwater Images Using Spectral Data2005Doctoral thesis, monograph (Other scientific)
  • 188.
    Åhlén, Julia
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Improvement of a Color Correction Algorithm for Underwater Images Through Compensating for Digital Camera Behaviour2004In: Proc. Swedish Symposium on Image Analysis / [ed] Bengtsson E., Eriksson M., 2004, p. 142-145Conference paper (Other academic)
  • 189.
    Åhlén, Julia
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Bengtsson, E
    On Colour Reconstruction of Underwater Images Taken in Shallow Waters2004In: Ocean Optics XVII, Fremantle, Australia, 2004, p. 25-29Conference paper (Other academic)
  • 190.
    Åhlén, Julia
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Bengtsson, E
    Sundgren, David
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för matematik och statistik.
    Evaluation of Underwater Spectral Data for Colour Correction Applications2006In: CSECS'06 Proceedings of the 5th WSEAS International Conference on Circuits, Systems, Electronics, Control & Signal Processing, 2006Conference paper (Other academic)
    Abstract [en]

    The inherent properties of water column usually affect underwater imagery by suppressing high-energy wavelengths. One of the inherent properties, diffuse attenuation, can be estimated from multi or hyper spectral data and thus give information on how fast light of different wavelengths decreases with increasing depth. Based on exact depth measurements and data from a spectrometer incoming light on an object can be calculated and diffuse attenuation coefficient can be estimated. In this work the authors introduce a mathematical model that suggests the most stable wavelengths, which corresponds to estimated coefficients, based on spectral information from each depth. These values are then used in reconstruction of colours in underwater imagery. Since there are no digital hyper spectral cameras yet we are for the time being confined to point data, but the method is general and we show how it can be applied on multi spectral images.

  • 191.
    Åhlén, Julia
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Bengtsson, Ewert
    Sundgren, David
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för matematik och statistik.
    Optimisation of Underwater Hyper Spectral Data for Colour Correction of Pseudo Hyper Spectral Images2006In: WSEAS Transactions on Signal Processing, ISSN 1790-5022, Vol. 2, no 11, p. 1473-1479Article in journal (Other academic)
  • 192.
    Åhlén, Julia
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Seipel, Stefan
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Prediction of Ventilation Paths in Urban Environments using Digitized Maps2009In: Proceedings of the IADIS International Conference Applied Computing 2009, 2009, p. 217-221Conference paper (Refereed)
  • 193.
    Åhlén, Julia
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Sundgren, David
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för matematik och statistik.
    Recognition of video sequences using low frequencies and color2008In: Advanced topics on signal processing, robotics and automation: proceedings of the 7th WSEAS International Conference on Signal Processing, Robotics and Automation (ISPRA '08), Cambridge, UK, February 20-22 2008, WSEAS , 2008, p. 204-207Conference paper (Refereed)
    Abstract [en]

    This paper presents a method for descriptive feature matching between two video streams of the same scene. The second video is a corrupted copy of the first video. Examples of reliable recognition of an original scene that is subjected for compression and noise are presented. The algorithm is invariant to image scale and rotation, providing robust matching across a substantial range of video signals. This paper shows an approach to using descriptive features for randomly chosen frames from video stream. By involving color information as a feature we increase the robustness of the identification process. The median of low frequencies is measured, followed by an average of spectral information from the same frame to identify clusters belonging to a scene in a film. Finally, a comparison analysis is done to verify the originality of the film.

  • 194.
    Åhlén, Julia
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Sundgren, David
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för matematik och statistik.
    Recognition of video signal by matching with the original video sequence2008In: Proceedings on CD-ROM, IADIS International Conference, 2008Conference paper (Refereed)
    Abstract [en]

    An adequate analysis of the originality of the video is of a great importance in video processing field. This paper presents a method for feature matching between two video streams. One of the video streams is subjected for severe compression, noise and rotation. These two copies represent the same movie but only one of the versions is original. Examples of reliable recognition of an original scene that is subjected for compression and noise are presented. The algorithm is invariant to image scale and rotation, providing robust matching across a substantial range of video signals. This paper shows an approach to using descriptive features for randomly chosen unstructured frames from video stream. By involving color information as a feature together with intensity profile for frame blocks we increase the robustness of the identification process. The median of low frequencies is measured, followed by an average of spectral information from the same frame to identify clusters belonging to a scene in a film. Finally, a comparison of mean squares of the difference is done to verify the originality of the film.

  • 195.
    Åhlén, Julia
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Sundgren, David
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för matematik och statistik.
    Bengtsson, Ewert
    CBA.
    Application of underwater hyperspectral data for color correction purposes2007In: Pattern recognition and image analysis, ISSN 1555-6212, Vol. 17, no 1, p. 170-173Article in journal (Refereed)
    Abstract [en]

    Color correction of underwater images has been considered a difficult task for a number of reasons. Those include severe absorption of the water column, the unpredictable behavior of light under the water surface, limited access to reliable data for correction purposes, and the fact that we are only able to process three spectral channels, which is insufficient for most color correction applications. Here, the authors present a method to estimate a hyperspectral image from an RGB image and pointwise hyperspectral data. This is then used to color correct the hyperspectral underwater image and transform it back into RGB color space.

  • 196.
    Åhlén, Julia
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Sundgren, David
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för matematik och statistik.
    Bengtsson, Ewert
    Pre-Processing of Underwater Images Taken in Shallow Waters for Color Reconstruction Purposes2005In: Proceedings of the 7th IASTED International Conference on Signal and Image Processing, 2005Conference paper (Refereed)
    Abstract [en]

    Coral reefs are monitored with different techniques in order to examine their health. Digital cameras, which provide an economically defendable tool for marine scientists to collect underwater data, tend to produce bluish images due to severe absorption of light at longer wavelengths. In this paper we study the possibilities of correcting for this color distortion through image processing. The decrease of red light by depth can be predicted by Beer's law. Another parameter that has to be taken into account is the image enhancement functions built into the camera. We use a spectrometer and a reflectance standard to obtain the data needed to approximate the joint effect of these functions. This model is used to pre-process the underwater images taken by digital cameras so that the red, green and blue channels show correct values before the images are subjected to correction for the effects of water column through application of Beer's law. This process is fully automatic and the amount of processed images is limited only by the speed of computer system. Experimental results show that the proposed method works well for correcting images taken at different depths with two different cameras.

  • 197.
    Åhlén, Julia
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Sundgren, David
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för matematik och statistik.
    Lindell, Tommy
    Dissolved Organic Matters Impact on Color Reconstruction of Underwater Images2005In: Proceedings of the 14th Scandinavian Conference on Image Analysis, 2005, p. 1148-1156Conference paper (Refereed)
    Abstract [en]

    The natural properties of water column usually affect underwater imagery by supressing high-energy light. In application such as color correction of underwater images estimation of water column parameters is crucial. Diffuse attenuation coefficients are estimated and used for further processing of underwater taken data. The coeeficients will give information on how fast light of different wavelengths decreases with increasing depth. Based on the exact depth measurements and data from a spectrometrer the calculation of downwelling irradiance will be done. Chlorophyll concentration and a yellow substance factor contribute to a great variety of values of attenuation coefficients at different depth. By taking advantage of variations in depth, a method is presented to estimate the influence of dissolved organic matters and chlorophyll on color correction. Attenuation coefficients that depends on concentration of dissolved organic matters in water gives an indication on how well any spectral band is suited for color correction algorithm.

  • 198.
    Åhman, Fredrik
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Hillström, Lars
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för naturvetenskap.
    Using a Game Theoretical Approach for Experimental Simulation of Brood Reduction: Conflict and Co-Operation, Effect on Brood Size with Limited Resources2005In: Proceedings of the Seventh International Conference on Enterprise Information Systems, 2005, p. 220-225Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    The evolution of parental care includes typical caring behaviour, such as protecting or feeding offspring. Sibling rivalry is anthropogenic viewed as conflicting behaviour, and can ultimately lead to brood reduction. In this study we have used object oriented programming to simulate different scenarios in this sibling rivalry conflict. A number of hypotheses have been proposed to explain the complex interactions occurring during brood reduction, but few simulation models successfully combines it with a hypothesis necessary to describe an ESS. In our solution we present a simple experimental simulation for brood reduction, where each sibling acts as an autonomous agent that has the ability to initiate actions for cooperation and competition against other siblings. Agents have a limited set of actions that can be activated during the onset of some specific environmental conditions, such as prey density, different climate variables etc. Parameters for food distribution are determined on a basis of a former known theory for maximizing inclusive fitness. In the computer simulations we have studied effects on sizes of siblings and fitness measures with varying degree of hatching patterns and prey density for siblings within the artificial brood. Results from the experimental simulations demonstrate interesting similarities with brood reduction in a real world setting, such as in raptorial birds that practice facultative siblicidal behaviour. Agents within the artificial brood respond with stronger conflicting behaviour whenever resources are limited and simulating increased hatching asynchrony lead to a lower survival rate (because of increased size hierarchy) of siblings within the simulated brood.

  • 199.
    Åström, Jesper
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Designvisualisering ur ”First person”-perspektiv2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    För att skapa kraftfullare presentationer måste nya metoder implementeras för att visualisera projekt. Ett aktivitetshus för ungdomar visualiseras i detta projekt genom att 3D-modellen av huset placeras i ett filmklipp från den plats där huset skall stå. Stegen som togs för att realisera detta var förarbete i form av inskaffande av ritningar, filmande, matchmoving, 3D-modellering, rendering, compositing och ljuddesign. Resultatet blev ett filmklipp som ur ett första persons perspektiv både visar exteriören och interiören.

  • 200.
    Öman, Maria
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Jonsson, Torsten
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Om ett pedagogiskt arbete på en högskoleavdelning2004In: Kunskap och lärande i den högre utbildningen: lärarreflexioner från praktiken / [ed] Sara Dahlström och Göran Fransson, Gävle: Högskolan i Gävle , 2004, p. 39-52Chapter in book (Other (popular science, discussion, etc.))
12345 151 - 200 of 201
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