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  • 1.
    Ahl, Ing-Marie
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Jonsson, Bengt-Harald
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology . Linköping University, The Institute of Technology.
    Tibell, Lena
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Thermodynamic Characterization of the Interaction between the C-Terminal Domain of Extracellular Superoxide Dismutase and Heparin by Isothermal Titration Calorimetry2009In: BIOCHEMISTRY, ISSN 0006-2960, Vol. 48, no 41, 9932-9940 p.Article in journal (Refereed)
    Abstract [en]

    Extracellular superoxide dismutase (ECSOD) interacts with heparin through its C-terminal domain. In this study we used isothermal titration calorimetry (ITC) to get detailed thermodynamic information about the interaction. We have shown that the interaction between ECSOD and intestinal mucosal heparin (M-w 6000-30000 Da) is exothermic and driven by enthalpy at physiological salt concentration. However, the contribution from entropy is favorable for binding or small isolated heparin fragments. By studying different size-defined heparin fragments, we also concluded that it hexasaccharide moiety is sufficient for strong binding to ECSOD. The binding involves proton transfer from the buffer to the ECSOD-heparin complex, and the results indicate that the number of ionic interactions made between ECSOD and heparin upon binding varies from three to five for heparin and an octasaccharide fragment, respectively. Surprisingly and despite the many charges found oil both the protein and the polysaccharide, our results indicate that the nonionic contribution to the binding is large. From the temperature dependence we have calculated the constant pressure heat capacity change (Delta C-p) of the interaction to -644 J K-1 mol(-1) and -306 J K-1 mol(-1) for heparin and all octasaccharide, respectively

  • 2.
    Ahl, Ing-Marie
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Jonsson, Bengt-Harald
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology . Linköping University, The Institute of Technology.
    Tibell, Lena A. E.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Analysis of Effects of Mutations in the C-Terminal Domain of Extracellular Superoxide Dismutase by Isothermal Titration Calorimetry and Phage DisplayManuscript (preprint) (Other academic)
    Abstract [en]

    n/a

  • 3.
    Ahl, Ing-Marie
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Nelson, Sally K
    Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, CO-800 45, Aurora, USA.
    Enström, Camilla
    Department of Medical Sciences, Uppsala University, SE-751 85, Uppsala, Sweden.
    Ericson, Ann-Charlotte
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Tibell, Lena A. E.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Cell Association and Protective Effects of PseudoECSOD: a progress reportManuscript (preprint) (Other academic)
    Abstract [en]

    n/a

  • 4.
    Almén, Edgar
    et al.
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Religion and Culture, Theology and Religious Studies.
    Hartman, Kent
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Automatic Control.
    Lennartsson, Bengt
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Hult, Håkan
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Behavioural Sciences, Studies in Adult, Popular and Higher Education.
    Examination - utveckling eller kontroll?2000Report (Other academic)
  • 5.
    Andel, Miroslav
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Petrovski, Alexander
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Henrysson, Anders
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Ollila, Mark
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Interactive Collaborative Scene Assembly Using AR on Mobile Phones2006In: Artificial Reality and Telexistence, ICAT, Springer , 2006, 1008-1017 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we present and evaluate a platform for interactive collaborative face-to-face Augmented Reality using a distributed scene graph on mobile phones. The results of individual actions are viewed on the screen in real-time on every connected phone. We show how multiple collaborators can use consumer mobile camera phones to furnish a room together in an Augmented Reality environment. We have also presented a user case study to investigate how untrained users adopt this novel technology and to study the collaboration between multiple users. The platform is totally independent of a PC server though it is possible to connect a PC client to be used for high quality visualization on a big screen device such as a projector or a plasma display.

  • 6.
    Andersson, Jonas
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Karlsson, David
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Improving rendering times of Autodesk Maya Fluids using the GPU2008Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fluid simulation is today a hot topic in computer graphics. New highly optimized algorithms have allowed complex systems to be simulated in high speed. This master thesis describes how the graphics processing unit, found in most computer workstations, can be used to optimize the rendering of volumetric fluids. The main aim of the work has been to develop a software that is capable of rendering fluids in high quality and with high performance using OpenGL. The software was developed at Filmgate, a digital effects company in Göteborg, and much time was spent making the interface and the workflow easy to use for people familiar with Autodesk Maya. The project resulted in a standalone rendering application, together with a set of plugins to exchange data between Maya and our renderer.

    Most of the goals have been reached when it comes to rendering features. The performance bottleneck turned out to be reading data from disc and this is an area suitable for future development of the software.

  • 7. Andersson, Robin
    et al.
    Vitoria, Aida
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Maluszynski, Jan
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, TCSLAB - Theoretical Computer Science Laboratory.
    Komorowski, Henryk Jan
    RoSy: A Rough Knowledge Base System2005In: Rough Sets, Fuzzy Sets, Data Mining, and Granular-Soft Computing,2005, Berlin: Springer , 2005, 48- p.Conference paper (Refereed)
  • 8.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Peterson, Stephen D.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Ellis, Stephen
    Human Systems Integration Division NASA Ames Research Center.
    User Boresight Calibration Precision for Large-Format Head-Up Displays2008In: Proceedings of the 2008 ACM symposium on Virtual reality software and technology, New York, NY, USA: ACM , 2008, 141-148 p.Conference 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.

  • 9.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Peterson, Stephen D.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Ellis, Stephen
    Human Systems Integration Division NASA Ames Research Center.
    User Boresight for AR Calibration: A Preliminary Analysis2008In: IEEE Virtual Reality Conference, 2008. VR '08 / [ed] Ming Lin, Anthony Steed, Carolina Cruz-Neira, Piscataway, NJ, USA: 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.

  • 10.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Peterson, Stephen D.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Ellis, Stephen R.
    NASA Ames Research Center.
    Visual Alignment Accuracy in Head Mounted Optical See-Through AR Displays: Distribution of Head Orientation Noise2009In: 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 (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.

  • 11.
    Axholt, Magnus
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Peterson, Stephen D.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Ellis, Stephen R.
    NASA Ames Research Center.
    Visual Alignment Precision in Optical See - Through AR Displays: Implications for Potential Accuracy2009In: Proceedings of the ACM/IEEE Virtual Reality International Conference, Association for Computing Machinery (ACM), 2009Conference 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.

  • 12.
    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.

  • 13. Banissi, Ebad
    et al.
    Stuart, LizWyeld, TheodorJern, MikaelAndrienko, GennadyMemon, NasrullahAlhajj, RedaBurkhard, RemoGrinstein, GeorgeGroth, DennisUrsyn, AnnaJohansson, JimmyLinköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.Forsell, CamillaLinköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.Cvek, UrskaTrutschl, MarjamMarchese, FrancisMaple, CarstenCowell, AndrewVande Moere, Andrew
    Information Visualization2009Conference proceedings (editor) (Other academic)
  • 14.
    Billinghurst, Mark
    et al.
    HITLabNZ University of Canterbury.
    Henrysson, Anders
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Research Directions in Handheld AR2006In: International journal of virtual reality, ISSN 1081-1451, Vol. 5, no 2, 51-58 p.Article in journal (Refereed)
  • 15.
    Bivall Persson, Petter
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology. Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Learning Molecular Interaction Concepts through Haptic Protein Visualization2008In: Proceedings of SIGRAD 2008 / [ed] Kai-Mikael Jää-Aro and Lars Kjelldahl, Linköping, Sweden: Linköping University Electronic Press , 2008, 17-19 p.Conference paper (Other academic)
    Abstract [en]

    The use of haptics is growing in the area of science education. Haptics appears to convey information to students in a manner that influences their learning and ways of thinking. This document outlines examples of how haptics has been employed in science education contexts and gives a more detailed description of an education oriented evaluation of a haptic protein-ligand docking system. In molecular life science, students need to grasp several complex concepts to understand molecular interactions. Research on how haptics influences students' learning show strong positive affective responses and, in the protein-ligand docking case, that reasoning with respect to molecular processes is altered. However, since many implications of using haptics in education are still unknown, more research is needed.

  • 16.
    Bivall Persson, Petter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology. Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Cooper, Matthew
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Tibell, Lena
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of cell biology.
    Visuella och haptiska modeller för underlättad förståelse för molekylers struktur och interaktioner2007In: 10:e Universitetspedagogiska konferensen vid Linköpings universitet: Pedagogiska utmaningar i tiden / [ed] Helene Hård af Segerstad, 2007, 43-47 p.Conference paper (Refereed)
  • 17.
    Bivall Persson, Petter
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Cooper, Matthew
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Tibell, Lena
    Linköping University, Department of Biomedicine and Surgery, Division of cell biology. Linköping University, Faculty of Health Sciences.
    Ainsworth, Shaaron
    Learning Sciences Research Institute, University of Nottingham, Nottingham, UK.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Jonsson, Bengt-Harald
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology. Linköping University, The Institute of Technology.
    Designing and Evaluating a Haptic System for Biomolecular Education2007In: IEEE Virtual Reality Conference, 2007. VR '07. / [ed] Sherman, W; Lin, M; Steed, A, Piscataway, NJ, USA: IEEE , 2007, 171-178 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we present an in situ evaluation of a haptic system, with a representative test population, we aim to determine what, if any, benefit haptics can have in a biomolecular education context. We have developed a haptic application for conveying concepts of molecular interactions, specifically in protein-ligand docking. Utilizing a semi-immersive environment with stereo graphics, users are able to manipulate the ligand and feel its interactions in the docking process. The evaluation used cognitive knowledge tests and interviews focused on learning gains. Compared with using time efficiency as the single quality measure this gives a better indication of a system's applicability in an educational environment. Surveys were used to gather opinions and suggestions for improvements. Students do gain from using the application in the learning process but the learning appears to be independent of the addition of haptic feedback. However the addition of force feedback did decrease time requirements and improved the students understanding of the docking process in terms of the forces involved, as is apparent from the students' descriptions of the experience. The students also indicated a number of features which could be improved in future development.

  • 18.
    Bivall Persson, Petter
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Cooper, Matthew
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Jonsson, Bengt-Harald
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology.
    Tibell, Lena
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of cell biology.
    Use of Chemical Force Feedback for Multisensory Insights into Ligand Docking2007In: VII European Symposium of The Protein Society: From Proteins to Proteome, 2007, 151-151 p.Conference paper (Refereed)
  • 19.
    Bivall Persson, Petter
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Höst, Gunnar E.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Cooper, Matthew D.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Tibell, Lena A. E.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Improved Feature Detection over Large Force Ranges Using History Dependent Transfer Functions2009In: Third Joint Eurohaptics Conference and Symposium on Haptic Interfaces for Virtual Environments and Teleoperator Systems, WorldHaptics 2009, IEEE , 2009, 476-481 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we present a history dependent transfer function (HDTF) as a possible approach to enable improved haptic feature detection in high dynamic range (HDR) volume data. The HDTF is a multi-dimensional transfer function that uses the recent force history as a selection criterion to switch between transfer functions, thereby adapting to the explored force range. The HDTF has been evaluated using artificial test data and in a realistic application example, with the HDTF applied to haptic protein-ligand docking. Biochemistry experts performed docking tests, and expressed that the HDTF delivers the expected feedback across a large force magnitude range, conveying both weak attractive and strong repulsive protein-ligand interaction forces. Feature detection tests have been performed with positive results, indicating that the HDTF improves the ability of feature detection in HDR volume data as compared to a static transfer function covering the same range.

  • 20.
    Bivall Persson, Petter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology. Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Rundgren, Carl-Johan A.
    Linköping University, Faculty of Educational Sciences. Linköping University, Department of Social and Welfare Studies, Natural Science - Medicine - Esthetics - Communication .
    Visualization and Haptics in Molecular Life Science - A Multi-sensory Representation of Proteins2006In: Third Scandinavian Symposium on Research in Science Education, 2006Conference paper (Other academic)
  • 21.
    Bivall Persson, Petter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology. Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Tibell, Lena
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of cell biology.
    Cooper, Matthew
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Using Force Feedback Virtual Reality Technology as a Tactile Gateway to Understanding of Biomolecular Interactions2006In: 9th JURE conference of EARLI, 2006Conference paper (Other academic)
  • 22.
    Bivall Persson, Petter
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology. Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA).
    Tibell, Lena
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of cell biology.
    Cooper, Matthew D.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Ainsworth, Shaaron
    Learning Sciences Research Institute University of Nottingham.
    Reasoning through Touch? Using Haptics in Life Science Education2007In: EARLI 2007 12th Biennial Conference for Research on Learning and Instruction, 2007Conference paper (Other academic)
  • 23.
    Bivall Persson, Petter
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Tibell, Lena
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of cell biology.
    Cooper, Matthew
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Jonsson, Bengt-Harald
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology.
    Evaluating the Effectiveness of Haptic Visualization in Biomolecular Education - Feeling Molecular Specificity in a Docking Task2006In: 12th IOSTE Symposium, Universiti Science Malaysia , 2006, 745-752 p.Conference paper (Refereed)
    Abstract [en]

    Within the molecular life sciences extensive use is made of visual representations, ranging from sketches to advanced computer graphics, often used to convey abstract knowledge that is difficult for the student to grasp. This work evaluates a new visual and haptic (tactile/kinetic) tool for protein docking in an in situ learning situation by combining qualitative and quantitative methods, performing tests and interviews with students; all aiming at a proper inclusion of visualization tools into biomolecular education. Preliminary results indicate time gains, strong positive affective responses and learning gains from the tasks, however the influence of haptics needs further investigation.

  • 24.
    Borghesi, M.
    et al.
    CPP, Queen's University Belfast, UK.
    Sarri, G.
    CPP, Queen's University Belfast, UK.
    Cecchetti, C. A.
    CNR, Ist Proc Chim Fis, I-56100 Pisa, Italy.
    Kourakis, I.
    CPP, Queen's University Belfast, UK.
    Hoarty, D.
    AWE Plc, Aldermaston, Reading, Berks England .
    Stevenson, R. M.
    AWE Plc, Aldermaston, Reading, Berks England .
    James, S.
    AWE Plc, Aldermaston, Reading, Berks England .
    Brown, C. D.
    AWE Plc, Aldermaston, Reading, Berks England .
    Hobbs, P.
    AWE Plc, Aldermaston, Reading, Berks England .
    Lockyear, J.
    AWE Plc, Aldermaston, Reading, Berks England .
    Morton, J.
    AWE Plc, Aldermaston, Reading, Berks England .
    Willi, O.
    Univ Dusseldorf, Inst Laser & Plasmaphys, Dusseldorf, Germany.
    Jung, R.
    Univ Dusseldorf, Inst Laser & Plasmaphys, Dusseldorf, Germany.
    Dieckmann, Mark E.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Progress in proton radiography for diagnosis of ICF-relevant plasmas2010In: Laser and particle beams (Print), ISSN 0263-0346, E-ISSN 1469-803X, Vol. 28, no 2, 277-284 p.Article in journal (Refereed)
    Abstract [en]

    Proton radiography using laser-driven sources has been developed as a diagnostic since the beginning of the decade, and applied successfully to a range of experimental situations. Multi-MeV protons driven from thin foils via the Target Normal Sheath Acceleration mechanism, offer, under optimal conditions, the possibility of probing laser-plasma interactions, and detecting electric and magnetic fields as well as plasma density gradients with similar to ps temporal resolution and similar to 5-10 mu m spatial resolution. In view of these advantages, the use of proton radiography as a diagnostic in experiments of relevance to Inertial Confinement Fusion is currently considered in the main fusion laboratories. This paper will discuss recent advances in the application of laser-driven radiography to experiments of relevance to Inertial Confinement Fusion. In particular we will discuss radiography of hohlraum and gasbag targets following the interaction of intense ns pulses. These experiments were carried out at the HELEN laser facility at AWE (UK), and proved the suitability of this diagnostic for studying, with unprecedented detail, laser-plasma interaction mechanisms of high relevance to Inertial Confinement Fusion. Non-linear solitary structures of relevance to space physics, namely phase space electron holes, have also been highlighted by the measurements. These measurements are discussed and compared to existing models.

  • 25.
    Bourgois, Marc
    et al.
    INO Eurocontrol Experimental Centre.
    Cooper, Matthew
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Duong, Vu
    UNO Eurocontrol Experimental Centre.
    Hjalmarsson, Jonas
    Linköping University, Department of Science and Technology.
    Lange, Marcus
    Linköping University, Department of Science and Technology.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Interactive and Immersive 3D Visualization for ATC2005In: USA/Europe Seminar on Air Traffic Management Research and Development,2005, Washinton, DC, USA: FAA , 2005, 303- p.Conference paper (Refereed)
  • 26.
    Bret, Antoine
    et al.
    ETSI Industriales Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain.
    Dieckmann, Mark E
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Relativistic electron beam driven instabilities in the presence of an arbitrarily oriented magnetic field2008In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 15, no 6, 062102-1- p.Article in journal (Refereed)
    Abstract [en]

    The electromagnetic instabilities driven by a relativistic electron beam, which moves through a magnetized plasma, are analyzed with a cold two-fluid model. It allows for any angle B between the beam velocity vector and the magnetic field vector and considers any orientation of the wavevector in the two-dimensional plane spanned by these two vectors. If the magnetic field is strong, the two-stream instability dominates if B=0 and the oblique modes grow faster at larger B. A weaker magnetic field replaces the two-stream modes with oblique modes as the fastest-growing waves. The threshold value separating both magnetic regimes is estimated. A further dimensionless parameter is identified, which determines whether or not the wavevector of the most unstable wave is changed continuously, as B is varied from 0 to /2. The fastest growing modes are always found for a transverse propagation of the beam with B=/2, irrespective of the magnetic field strength. ©2008 American Institute of Physics

  • 27.
    Bret, Antoine
    et al.
    ETSI Ind Univ Castilla-La Mancha.
    Dieckmann, Mark E
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Deutsch, Claude
    Phys Gas Plasma Lab Univ Paris 11, Orsay.
    Magnetic field effects on instabilities driven by a field-aligned relativistic warm electron beam and warm bulk electrons2007In: 34th European Physical Society Conference on Plasma Physics,2007, Warsaw: European Physical Society , 2007, P2.079- p.Conference paper (Refereed)
    Abstract [en]

    Instabilities driven by relativistic electron beams are being investigated due to their importance for plasma heating and electromagnetic field generation in astrophysical and laboratory plasmas. Particle-in-cell (PIC) simulations of initially unmagnetized colliding plasmas have demonstrated the generation of strong magnetic fields and a moderate electron acceleration. The inclusion of a flow-aligned magnetic field suppresses the electromagnetic filamentation instability and PIC simulations have shown that the plasma dynamics turns quasi-electrostatic. To quantify the impact of the magnetic field, we have analyzed numerically a magnetized multi-fluid model that includes a kinetic pressure term. This fluid model allows us to examine the beam-driven instability at all angles between the wavevector and the magnetic field vector. More accurate kinetic models typically focus only on the filamentation instability, due to the increased analytical complexity. We present here the fluid model and a growth rate map of the entire k-space for a beam Lorentz factor 4. We verify that the two-stream, mixed mode and filamentation instability belong to the same wave branch and that the magnetic field selects the fastest-growing mode. We estimate the magnetic fields required to suppress the filamentation and the mixed mode instabilities.

  • 28.
    Bret, Antoine
    et al.
    Universidad de Castilla-La Mancha, Spain.
    Dieckmann, Mark Eric
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    How large can the electron to proton mass ratio be in particle-in-cell simulations of unstable systems?2010In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 17, no 3, 032109- p.Article in journal (Refereed)
    Abstract [en]

    Particle-in-cell simulations are widely used as a tool to investigate instabilities that develop between a collisionless plasma and beams of charged particles. However, even on contemporary supercomputers, it is not always possible to resolve the ion dynamics in more than one spatial dimension with such simulations. The ion mass is thus reduced below 1836 electron masses, which can affect the plasma dynamics during the initial exponential growth phase of the instability and during the subsequent nonlinear saturation. The goal of this article is to assess how far the electron to ion mass ratio can be increased, without changing qualitatively the physics. It is first demonstrated that there can be no exact similarity law, which balances a change in the mass ratio with that of another plasma parameter, leaving the physics unchanged. Restricting then the analysis to the linear phase, a criterion allowing to define a maximum ratio is explicated in terms of the hierarchy of the linear unstable modes. The criterion is applied to the case of a relativistic electron beam crossing an unmagnetized electron-ion plasma.

  • 29. Costantini, Stefania
    et al.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Pereira, Luis
    A Multi-layer Framework for Evolving and Learning Agents2008In: Procs. Metareasoning: Thinking about thinking workshop at AAAI 2008,2008, 2008Conference paper (Refereed)
  • 30.
    Costantini, Stefania
    et al.
    Dept. of Computer Science Univ. of LAquila.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Pereira, Luis Moniz
    Dept. of Computer Science New University of Lisbon.
    Toni, Francesca
    Dept. of Computer Science Imperial College London.
    Towards a Model of Evolving Agents for Ambient Intelligence2007In: Symposium on Artificial Societies for Ambient Intelligence ASAmI07,2007, Newcastle: AISB , 2007Conference paper (Refereed)
  • 31.
    Costantini, Stefania
    et al.
    Dip. di Informatica, Universit`a di L’Aquila, Coppito 67100, L’Aquila, Italy.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Pereira, Luis Moniz
    Departamento de Informatica, Centro de Inteligencia Artificial (CENTRIA), Universidade Nova de Lisboa, Portugal.
    Tsintza, Panagiota
    Dip. di Informatica, Universit`a di L’Aquila, Coppito 67100, L’Aquila, Italy.
    Runtime Verification of Agent Properties2009In: Int. Conf. on Applications of Declarative Programming and Knowledge Management (INAP09) / [ed] Salvador Abreu and Dietmar Seipel, 2009, 257-271 p.Conference paper (Refereed)
  • 32. Costantini, Stefania
    et al.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Pereira, Luis
    Tsintza, Panagiota
    Specification and Dynamic Verification of Agent Properties2008In: 9th Intl. Ws. on Computational Logic in Multi-Agent Systems CLIMA,2008, 2008Conference paper (Refereed)
  • 33.
    Costantini, Stefania
    et al.
    Dip. Informatica Universita degli Studi di LAquila.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Tocchio, Arianna
    Dip. Informatica Universita degli Studi di LAquila.
    Expressing preferences declaratively in logic-based agent languages2006In: Dagli Oggetti agli Agenti: Sistemi Intelligenti e Computazione Pervasiva,2006, Catania: CEUR Workshop Proceedings , 2006Conference paper (Refereed)
  • 34.
    Costantini, Stefania
    et al.
    Dept. of Computer Science Univ. of LAquila.
    Tocchio, Arianna
    Dept. of Computer Science Univ. of LAquila.
    Dell'Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Expressing Preferences Declaratively in Logic-based Agent Languages2007In: International Symposium on Logical Formalizations of Commonsense Reasoning,2007, Stanford: AAAI Spring Symposium Series, Stanford University , 2007Conference paper (Refereed)
  • 35.
    Dang, Nguyen Thong
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    A Survey and Classification of 3D Pointing Techniques2007In: IEEE International Conference on Research, Innovation and Vision for the Future, 2007, Piscataway, N.J. USA: IEEE , 2007, 71-80 p.Conference paper (Refereed)
    Abstract [en]

    This paper introduces a survey and a classification of 3D pointing techniques. The survey presents a chronological view on the study of 3D pointing techniques. The classification is based on a proposed definition of 3D cursor. The paper shows that existing 3D pointing techniques can be either 3D pointer-based cursor or 3D line-based cursor. Based on recent results of 3D Fitts- law study and the definition of two types of 3D cursor, the paper discusses different virtual enhancements for improving existing 3D pointing techniques and for creating and evaluating new 3D pointing techniques which focus on decreasing the average target acquisition time.

  • 36.
    Dang, Nguyen Thong
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Cooper, Matthew D.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Bourgois, Marc
    EUROCONTROL Experimental Centre, France.
    A Survey on Controller Weather Information Needs and 3D Weather Visualization2006In: EUROCONTROL Innovative Research Workshop,2006, Bruxelles, BE: EUROCONTROL , 2006, 69-79 p.Conference paper (Other academic)
  • 37.
    Dang, Nguyen Thong
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Cooper, Matthew D.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Bourgois, Marc
    EUROCONTROL Experimental Centre, France.
    Design of an Evaluation on Multimodal Interaction in a 3D Visualization Environment for Air Traffic Control2006In: Visualization and Distributed System Technologies: the AD4 Approach and Beyond,2006, 2006, 122-135 p.Conference paper (Other academic)
  • 38.
    Dang, Nguyen Thong
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Tavanti, Monica
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Rankin, Ivan
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Cooper, Matthew
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    A comparison of different input devices for a 3D environment2007In: European Conference on Cognitive Ergonomics 2007,2007, London: ACM Press , 2007, 153- p.Conference paper (Refereed)
    Abstract [en]

    Motivation - To identify a suitable interaction modality -among the ones currently implemented in a three-dimensional (3D) environment for Air Traffic Control- for allowing interactive exploration of and gathering information about 3D weather structures. Research approach - A usability study entailing four interaction modalities (also called -interaction interfaces-): voice, wand, pen and sketch interfaces, across a task requiring 3D surface exploration, information gathering and recall of information. Quantitative data (time, errors and a composite performance index) as well as qualitative data were collected. Findings/Design - Overall, the results indicate that the wand supported a better performance when compared to the other interaction interfaces. Among the four interaction interfaces, the voice interface seems to present additional limitations, mostly related to time lag in the voice recognition, that were judged as a source of frustration. Originality/Value - The present work provides empirical results deriving from a comparative usability study of four interaction interfaces; it contributes to the study of interaction in 3D environments with new empirical data.

  • 39.
    Dell Acqua, Pierangelo
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Weighted multi dimensional logic programs2004In: Computational Logic in Multi-Agent Systems: 4th International Workshop, CLIMA IV, Fort Lauderdale, FL, USA, January 6-7, 2004, Revised Selected and Invited Papers / [ed] Jürgen Dix and João Leite, Springer Berlin/Heidelberg, 2004, 1, Vol. 3259, 178-200 p.Chapter in book (Refereed)
    Abstract [en]

    This book constitutes the strictly refereed post-proceedings of the 4th International Workshop on Computational Logic for Multi-Agent Systems, CLIMA IV, held in Fort Lauderdale, Fl, USA in January 2004.  The 11 revised full papers presented together with 2 invited papers were carefully selected during two rounds of reviewing and improvement. The papers are devoted to techniques from computational logic for representing, programming, and reasoning about multi-agent systems. The papers are organized in topical sections on negotiation in MAS, planning in MAS, knowledge revision and update in MAS, and learning in BDI MAS.

  • 40.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Engberg, Mattias
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Pereira, Luís Moniz
    Universidade Nova de Lisboa, Caparica, Portugal.
    An architecture for a rational reactive agent2003In: Progress in Artificial Intelligence: 11th Portuguese Conference on Artificial Intelligence, EPIA 2003, Beja, Portugal, December 4-7, 2003. Proceedings / [ed] Fernando Moura Pires and Salvador Abreu, Springer Berlin/Heidelberg, 2003, Vol. 2902, 379-393 p.Chapter in book (Refereed)
    Abstract [en]

    We present an architecture for a rational, reactive agent and describe its implementation. The paper addresses issues raised by the interaction of the rational and reactive behaviour of the agent, and its updating mechanism. We relate it with the work of others.

  • 41.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Lombardi, Anna
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Modelling and simulating a simple virtual animal - An artificial fish2006In: Reglermöte 2006,2006, Poster , 2006Conference paper (Other academic)
  • 42.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Lombardi, Anna
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Pereira, Luis Moniz
    Universidade Nova de Lisboa, Caparica, Portugal.
    A logic-based approach to model supervisory control systems2006In: Foundations of Intelligent Systems: 16th International Symposium, ISMIS 2006, Bari, Italy, September 27-29, 2006. Proceedings / [ed] Floriana Esposito, Zbigniew W. Ras, Donato Malerba and Giovanni Semeraro, Springer Berlin/Heidelberg, 2006, Vol. 4203, 534-539 p.Chapter in book (Refereed)
    Abstract [en]

    We present an approach to model supervisory control systems based on extended behaviour networks. In particular, we employ them to formalize the control theory of the supervisor. By separating the reasoning in the supervisor and the action implementation in the controller, the overall system architecture becomes modular, and therefore easily changeable and modifiable.

  • 43.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Lombardi, Anna
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Pereira, Luis Moniz
    CENTRIA New University of Lisbon, Lisbon, Portugal.
    Modelling Adaptive Controllers with Evolving Logic Programming2006In: Informatics in Control, Automation and Robotics,2006, Procs. Intelligent Control Systems and Optimization Vol.1. ISBN:972-8865-59-7: INSTICC Press , 2006, 107- p.Conference paper (Refereed)
  • 44.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Lombardi, Anna
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Pereira, Luis Moniz
    CENTRIA New University of Lisbon, Lisbon, Portugal.
    Modelling Hybrid Control Systems with Behaviour Networks2005In: Informatics in Control, Automation and Robotics,2005, Portugal: INSTICC , 2005, 98- p.Conference paper (Refereed)
  • 45.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Nilsson, Ulf
    Linköping University, Department of Computer and Information Science, TCSLAB - Theoretical Computer Science Laboratory. Linköping University, The Institute of Technology.
    Pereira, L.
    Universidade Nova de Lisboa.
    A Logic Based Asynchronous Multi-Agent System2002In: Electronical Notes in Theoretical Computer Science, ISSN 1571-0661, E-ISSN 1571-0661, Vol. 70, no 5, 72-88 p.Article in journal (Refereed)
    Abstract [en]

    We present a logic programming based asynchronous multi-agent system in which agents can communicate with one another; update themselves and each other; abduce hypotheses to explain observations, and use them to generate actions. The knowledge base of the agents is comprised of generalized logic programs, integrity constraints, active rules, and of abducibles. We characterize the interaction among agents via an asynchronous transition rule system, and provide a stable models based semantics. An example is developed to illustrate how our approach works.

  • 46.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Nilsson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, TCSLAB - Theoretical Computer Science Laboratory.
    Pereira, L.M.
    Centro de Inteligcncia Artificial - CENTRIA, Departamento de Informática, Faculdade de Cicncias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
    A logic based asynchronous multi-agent system2002Conference paper (Other academic)
    Abstract [en]

    We present a logic programming based asynchronous multi-agent system in which agents can communicate with one another, update themselves and each other, abduce hypotheses to explain observations, and use them to generate actions. The knowledge base of the agents is comprised of generalized logic programs, integrity constraints, active rules, and of abducibles. We characterize the interaction among agents via an asynchronous transition rule system, and provide a stable models based semantics. An example is developed to illustrate how our approach works. © 2002 Published by Elsevier Science B.V.

  • 47.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Pereira, L.M.
    Centro de Inteligência Artificial - CENTRIA, Departamento de Informática, Faculdade de Ciências e Tecnologia, 2829-516 Caparica, Portugal.
    Preferential theory revision2007In: Journal of Applied Logic, ISSN 1570-8683, E-ISSN 1570-8691, Vol. 5, no 4 SPEC. ISS., 586-601 p.Article in journal (Refereed)
    Abstract [en]

    Employing a logic program approach, this paper focuses on applying preferential reasoning to theory revision, both by means of preferences among existing theory rules, and by means of preferences on the possible abductive extensions to the theory. And, in particular, how to prefer among plausible abductive explanations justifying observations. © 2006 Elsevier B.V. All rights reserved.

  • 48.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Pereira, Luis Moniz
    Universidade Nova de Lisboa, Caparica, Portugal.
    A Logical Framework for Modelling eMAS2002In: Practical Aspects of Declarative Languages: 5th International Symposium, PADL 2003 New Orleans, LA, USA, January 13–14, 2003 Proceedings / [ed] Veronica Dahl and Philip Wadler, Springer Berlin/Heidelberg, 2002, Vol. 2562, 241-255 p.Chapter in book (Refereed)
    Abstract [en]

    We investigate how to explicitly represent organizational structures in epistemic multi-agent systems (eMAS). We introduce a logical framework F suitable for representing organizational structures for epistemic agents, and provide its declarative and procedural semantics. We show how a number of organizational structures can be represented in F and discuss their properties.

  • 49.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Pereira, Luis Moniz
    Universidade Nova de Lisboa.
    Common-sense reasoning as proto-scientific agent activity2004In: Journal of Applied Logic, ISSN 1570-8683, E-ISSN 1570-8691, Vol. 2, no 4, 385-407 p.Article in journal (Refereed)
    Abstract [en]

    We wish to model common-sense reasoning in situations where it contains some of the ingredients typical of proto-scientific reasoning, with a view to future elaboration and proof of concept. To model this proto-scientific narrative, we employ the integrative formal computational machinery we have been developing and implementing for rational cooperative epistemi agents. In our logic-based framework, agents can update their own and each other's theories, which are comprised of knowledge, active rules, integrity constraints, queries, abducibles, and preferences, they can engage in abductive reasoning involving updatable preferences, set each other queries, react to circumstances, plan and carry out actions, and revise their theories and preferences by means of concurrent updates on self and others.

  • 50.
    Dell'Acqua, Pierangelo
    et al.
    Linköping University, Department of Science and Technology, Visual Information Technology and Applications (VITA). Linköping University, The Institute of Technology.
    Pereira, Luis Moniz
    Universidade Nova de Lisboa, Caparica, Portugal.
    Preference revision via declarative debugging2005In: Progress in Artificial Intelligence: 12th Portuguese Conference on Artificial Intelligence, EPIA 2005, Covilhã, Portugal, December 5-8, 2005. Proceedings / [ed] Carlos Bento, Amílcar Cardoso and Gaël Dias, Springer Berlin/Heidelberg, 2005, Vol. 3808, 18-28 p.Chapter in book (Refereed)
    Abstract [en]

    Preference criteria are rarely static. Often they are subject to modification and aggregation. The resulting preference criteria may not satisfy the properties of the original ones and must therefore be revised. This paper investigates the problem of revising such preference criteria by means of declarative debugging techniques.

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