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  • 1.
    Abrahamsson, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Pettersson, Rasmus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Smoothing of initial conditions for high order approximations in option pricing2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this article the Finite Difference method is used to solve the Black Scholes equation. A second order and fourth order accurate scheme is implemented in space and evaluated. The scheme is then tried for different initial conditions. First the discontinuous pay off function of a European Call option is used. Due to the nonsmooth charac- teristics of the chosen initial conditions both schemes show an order of two. Next, the analytical solution to the Black Scholes is used when t=T/2. In this case, with a smooth initial condition, the fourth order scheme shows an order of four. Finally, the initial nonsmooth pay off function is modified by smoothing. Also in this case, the fourth order method shows an order of convergence of four. 

  • 2.
    Adamovic, Nadja
    et al.
    TU Wien, ISAS, Vienna, Austria..
    Asinari, Pietro
    Politecn Torino, Dept Energy, Turin, Italy..
    Goldbeck, Gerhard
    Goldbeck Consulting Ltd, St Johns Innovat Ctr, Cambridge, England..
    Hashibon, Adham
    Fraunhofer Inst Mech Mat IWM, Freiburg, Germany..
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hristova-Bogaerds, Denka
    DPI, Eindhoven, Netherlands..
    Koopmans, Rudolf
    Koopmans Consulting GmbH, Zurich, Switzerland..
    Verbrugge, Tom
    Dow Benelux BV, Hoek, Netherlands..
    Wimmer, Erich
    Mat Design, Le Mans, France..
    European Materials Modelling Council2017In: Proceedings Of The 4Th World Congress On Integrated Computational Materials Engineering (Icme 2017) / [ed] Mason, P Fisher, CR Glamm, R Manuel, MV Schmitz, GJ Singh, AK Strachan, A, Springer Publishing Company, 2017, p. 79-92Conference paper (Refereed)
    Abstract [en]

    The aim of the European Materials Modelling Council (EMMC) is to establish current and forward looking complementary activities necessary to bring the field of materials modelling closer to the demands of manufacturers (both small and large enterprises) in Europe. The ultimate goal is that materials modelling and simulation will become an integral part of product life cycle management in European industry, thereby making a strong contribution to enhance innovation and competitiveness on a global level. Based on intensive efforts in the past two years within the EMMC, which included numerous consultation and networking actions with representatives of all stakeholders including Modellers, Software Owners, Translators and Manufacturers in Europe, the EMMC identified and proposed a set of underpinning and enabling actions to increase the industrial exploitation of materials modelling in Europe. EMMC will pursue the following overarching objectives in order to bridge the gap between academic innovation and industrial application: enhance the interaction and collaboration between all stakeholders engaged in different types of materials modelling, including modellers, software owners, translators and manufacturers, facilitate integrated materials modelling in Europe building on strong and coherent foundations, coordinate and support actors and mechanisms that enable rapid transfer of materials modelling from academic innovation to the end users and potential beneficiaries in industry, achieve greater awareness and uptake of materials modelling in industry, in particular SMEs, elaborate Roadmaps that (i) identify major obstacles to widening the use of materials modelling and (ii) elaborate strategies to overcome them.

  • 3.
    Afram, Rabi
    Gotland University, School of Game Design, Technology and Learning Processes.
    Puzzle Design in Adventure Games2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the level of difficulty of puzzles in the adventure games and the implications thereof. The thesis contains an in-depth background, and a brief history about the genre. It brings up the main problem of the genre and looks into both the cause and effect that follows. To support this process, an analysis has been made of design documents and a survey was issued on the subject of adventure game puzzles.

  • 4.
    Alemayehu, Brook
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Johnsons, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Maskininlärning inom kommersiella fastigheter: Prediktion av framtida hyresvakanser2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis is to investigate the possibilities of predicting vacancies in the real estate market by using machine learning models in terms of classification. These models were mainly based on data from contracts between a Swedish real estate company and their tenants. Attributes such as annual renting cost and rental area for each contract were supplemented with additional data regarding financial and geographical information about the tenants. The data was stored in three different formats with the first having binary classes which aim is to predict if the tenant is moving out within a year or more. The format of the second and third version were both multi classification problems that aims to classify if the tenants might terminate their contract within a specific interval with the length of three and six months.

    Based on the results from Microsoft Azure Machine Learning Studio, it is discovered that the multi classification problems perform rather poorly due to the classes being unbalanced. Regarding the  performance of the binary model, a more satisfying result was obtained but not to the extend to say that the model can be used to determine a vacancy with high accuracy. It should rather be used as a risk analysis tool to detect if a tenant is showing tendencies that could result in a future vacancy. A major pitfall of this thesis was the lack of data and the financial information not being specific enough. The performance of the models will likely increase with a larger dataset and more accurate financial information. 

  • 5.
    Allalou, Amin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Curic, Vladimir
    Pardo-Martin, Carlos
    Massachusetts Institute of Technology, USA.
    Yanik, Mehmet Fatih
    Massachusetts Institute of Technology, USA.
    Wählby, Carolina
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Approaches for increasing throughput andinformation content of image-based zebrafishscreens2011In: Proceeding of SSBA 2011, 2011Conference paper (Other academic)
    Abstract [en]

    Microscopy in combination with image analysis has emerged as one of the most powerful and informativeways to analyze cell-based high-throughput screening (HTS) samples in experiments designed to uncover novel drugs and drug targets. However, many diseases and biological pathways can be better studied in whole animals, particularly diseases and pathways that involve organ systems and multicellular interactions, such as organ development, neuronal degeneration and regeneration, cancer metastasis, infectious disease progression and pathogenesis. The zebrafish is a wide-spread and popular vertebrate model of human organfunction and development, and it is unique in the sense that large-scale in vivo genetic and chemical studies are feasible due in part to its small size, optical transparency,and aquatic habitat. To improve the throughput and complexity of zebrafish screens, a high-throughput platform for cellular-resolution in vivo chemical and genetic screens on zebrafish larvae has been developed at Yanik lab at Research Laboratory of Electronics, MIT, USA. The system loads live zebrafish from reservoirs or multiwell plates, positions and rotates them for high-speed confocal imaging of organs,and dispenses the animals without damage. We present two improvements to the described system, including automation of positioning of the animals and a novel approach for brightfield microscopy tomographic imaging of living animals.

  • 6.
    Allalou, Amin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    van de Rijke, Frans
    Jahangir Tafrechi, Roos
    Raap, Anton
    Wählby, Carolina
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Image based measurements of single cell mtDNA mutation load MTD 20072007In: Medicinteknikdagarna 2007, 2007Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Cell cultures as well as cells in tissue always display a certain degree of variability,and measurements based on cell averages will miss important information contained in a heterogeneous population. These differences among cells in a population may be essential to quantify when looking at, e.g., protein expression and mutations in tumor cells which often show high degree of heterogeneity.

    Single nucleotide mutations in the mithochondrial DNA (mtDNA) can accumulate and later be present in large proportions of the mithocondria causing devastating diseases. To study mtDNA accumulation and segregation one needs to measure the amount of mtDNA mutations in each cell in multiple serial cell culture passages. The different degrees of mutation in a cell culture can be quantified by making measurements on individual cells as an alternative to looking at an average of a population. Fluorescence microscopy in combination with automated digital image analysis provides an efficient approach to this type of single cell analysis.

    Image analysis software for these types of applications are often complicated and not easy to use for persons lacking extensive knowledge in image analysis, e.g., laboratory personnel. This paper presents a user friendly implementation of an automated method for image based measurements of mtDNA mutations in individual cells detected with padlock probes and rolling-circle amplification (RCA). The mitochondria are present in the cell’s cytoplasm, and here each cytoplasm has to be delineated without the presence of a cytoplasmic stain. Three different methods for segmentation of cytoplasms are compared and it is shown that automated cytoplasmic delineation can be performed 30 times faster than manual delineation, with an accuracy as high as 87%. The final image based measurements of mitochondrial mutation load are also compared to, and show high agreement with, measurements made using biochemical techniques.

  • 7.
    Almquist, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Numerical wave propagation in large-scale 3-D environments2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    High-order accurate finite difference methods have been applied to the acoustic wave equation in discontinuous media and curvilinear geometries, using the SBP-SAT method. Strict stability is shown for the 2-D wave equation with general boundary conditions. The fourth-order accurate method for the 3-D wave equation has been implemented in C and parallelized using MPI. The implementation has been verified against an analytical solution and runs efficiently on a large number of processors.

  • 8.
    Andreasson, Rebecca
    et al.
    University of Skövde, School of Informatics.
    Riveiro, Maria
    University of Skövde, School of Informatics.
    Effects of Visualizing Missing Data: An Empirical Evaluation2014In: 18th International Conference on Information Visualisation (IV) / [ed] Ebad Banissi, Mark W. McK. Bannatyne, Francis T. Marchese, Muhammad Sarfraz, Anna Ursyn, Gilles Venturini, Theodor G. Wyeld, Urska Cvek, Marjan Trutschl, Georges Grinstein, Vladimir Geroimenko, Sarah Kenderdine & Fatma Bouali, 2014, p. 132-138Conference paper (Refereed)
    Abstract [en]

    This paper presents an empirical study that evaluates the effects of visualizing missing data on decision-making tasks. A comparison between three visualization techniques: (1) emptiness, (2) fuzziness, and (3) emptiness plus explanation, revealed that the latter technique induced significantly higher degree of decision-confidence than the visualization technique fuzziness. Moreover, emptiness plus explanation yield the highest number of risky choices of the three. This result suggests that uncertainty visualization techniques affect the decision-maker and the decision-confidence. Additionally, the results indicate a possible relation between the degree of decision-confidence and the decision-maker's displayed risk behavior.

  • 9.
    Aronsson, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Crondahl, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Maskininlärning applicerat på data över biståndsinsatser: En studie i hur prediktiva modeller kan tillämpas för analys på Sida2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this master's thesis was to study if machine learning can be used asdecision support at the Swedish International Development Agency (Sida) in their work to provide financial aid. The aim was to examine the recurringphenomenon of increased number of aid disbursements towards the end of the year. A study and presentation of the data has been done to show the disbursementdistribution of Sida's operating departments. Moreover, qualitative interviews with different roles at Sida have been done to highlight the complexity of the agency and toexplain why and how different disbursement patterns occur. The approach has been to use classification models as well as regression models applied to data ofaid contributions from Sida's database. The classification models used were Decision Tree, k-Nearest Neighbour and Gradient Boosted Tree and thepurpose with the models was to illustrate which features of a contribution that are likely to be of importance for whether a disbursement occurs in December or earlier.The regression models used were linear models with the aim to predict if disbursements are likely to be delayed relative to the prognosis. The classificationmodel succeeded to point out three attributes that had influence on the classification result. The general conclusions of the report are that data ofcontributions generated in different IT-systems and various work routines at Sida's departments affect the quality of the data and the models’ accuracies negatively.Furthermore, insufficient amounts of data due to changes in Sida's information management has created difficulties when using data driven models to predict latedisbursements.

  • 10.
    Arweström Jansson, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Axelsson, AntonUppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.Andreasson, RebeccaUppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.Billing, ErikUniversity of Skövde.
    Proceedings of the 13th SweCog Conference2017Conference proceedings (editor) (Refereed)
  • 11.
    Asplund, Teo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Luengo Hendriks, Cris L.
    Flagship Biosci Inc, Westminster, CO 80021 USA.
    A Faster, Unbiased Path Opening by Upper Skeletonization and Weighted Adjacency Graphs2016In: IEEE Transactions on Image Processing, ISSN 1057-7149, E-ISSN 1941-0042, Vol. 25, no 12, p. 5589-5600Article in journal (Refereed)
    Abstract [en]

    The path opening is a filter that preserves bright regions in the image in which a path of a certain length L fits. A path is a (not necessarily straight) line defined by a specific adjacency relation. The most efficient implementation known scales as O(min(L, d, Q)N) with the length of the path, L, the maximum possible path length, d, the number of graylevels, Q, and the image size, N. An approximation exists (parsimonious path opening) that has an execution time independent of path length. This is achieved by preselecting paths, and applying 1D openings along these paths. However, the preselected paths can miss important structures, as described by its authors. Here, we propose a different approximation, in which we preselect paths using a grayvalue skeleton. The skeleton follows all ridges in the image, meaning that no important line structures will be missed. An H-minima transform simplifies the image to reduce the number of branches in the skeleton. A graph-based version of the traditional path opening operates only on the pixels in the skeleton, yielding speedups up to one order of magnitude, depending on image size and filter parameters. The edges of the graph are weighted in order to minimize bias. Experiments show that the proposed algorithm scales linearly with image size, and that it is often slightly faster for longer paths than for shorter paths. The algorithm also yields the most accurate results- as compared with a number of path opening variants-when measuring length distributions.

  • 12. Atzmueller, Martin
    et al.
    Gaito, Sabrina
    Interdonato, Roberto
    Kanawati, Rushed
    Largeron, Christine
    Magnani, Matteo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Sala, Alessandra
    International Workshop on Mining Attributed Networks (MATNET 2018) Chairs’ Welcome2018Other (Other academic)
  • 13.
    Bahceci, Ertin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    High performance computing and visualization of football match results - from algorithms built up using methods from modeling complex systems2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The evaluation of football players during and after a football match is an important field of study for football trainers and also people in academia. In this project some of the achieved theoretical results are implemented. Scientific findings are put into a context where the broader general public is able to understand the research. The ultimate goal is to produce visualizations such that they can be integrated into an application called Twelve where an everyday user can access them.

  • 14.
    Barkino, Iliam
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Summary Statistic Selection with Reinforcement Learning2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Multi-armed bandit (MAB) algorithms could be used to select a subset of the k most informative summary statistics, from a pool of m possible summary statistics, by reformulating the subset selection problem as a MAB problem. This is suggested by experiments that tested five MAB algorithms (Direct, Halving, SAR, OCBA-m, and Racing) on the reformulated problem and comparing the results to two established subset selection algorithms (Minimizing Entropy and Approximate Sufficiency). The MAB algorithms yielded errors at par with the established methods, but in only a fraction of the time. Establishing MAB algorithms as a new standard for summary statistics subset selection could therefore save numerous scientists substantial amounts of time when selecting summary statistics for approximate bayesian computation.

  • 15.
    Barrera, Tony
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Hast, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Bengtsson, Ewert
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    A chronological and mathematical overview of digital circle generation algorithms: Introducing efficient 4- and 8-connected circles2016In: International Journal of Computer Mathematics, ISSN 0020-7160, E-ISSN 1029-0265, Vol. 93, no 8, p. 1241-1253Article in journal (Refereed)
    Abstract [en]

    Circles are one of the basic drawing primitives for computers and while the naive way of setting up an equation for drawing circles is simple, implementing it in an efficient way using integer arithmetic has resulted in quite a few different algorithms. We present a short chronological overview of the most important publications of such digital circle generation algorithms. Bresenham is often assumed to have invented the first all integer circle algorithm. However, there were other algorithms published before his first official publication, which did not use floating point operations. Furthermore, we present both a 4- and an 8-connected all integer algorithm. Both of them proceed without any multiplication, using just one addition per iteration to compute the decision variable, which makes them more efficient than previously published algorithms.

  • 16.
    Bauer, Pavol
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Parallelism in Event-Based Computations with Applications in Biology2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Event-based models find frequent usage in fields such as computational physics and biology as they may contain both continuous and discrete state variables and may incorporate both deterministic and stochastic state transitions. If the state transitions are stochastic, computer-generated random numbers are used to obtain the model solution. This type of event-based computations is also known as Monte-Carlo simulation.

    In this thesis, I study different approaches to execute event-based computations on parallel computers. This ultimately allows users to retrieve their simulation results in a fraction of the original computation time. As system sizes grow continuously or models have to be simulated at longer time scales, this is a necessary approach for current computational tasks.

    More specifically, I propose several ways to asynchronously simulate such models on parallel shared-memory computers, for example using parallel discrete-event simulation or task-based computing. The particular event-based models studied herein find applications in systems biology, computational epidemiology and computational neuroscience.

    In the presented studies, the proposed methods allow for high efficiency of the parallel simulation, typically scaling well with the number of used computer cores. As the scaling typically depends on individual model properties, the studies also investigate which quantities have the greatest impact on the simulation performance.

    Finally, the presented studies include other insights into event-based computations, such as methods how to estimate parameter sensitivity in stochastic models and how to simulate models that include both deterministic and stochastic state transitions.

    List of papers
    1. Sensitivity estimation and inverse problems in spatial stochastic models of chemical kinetics
    Open this publication in new window or tab >>Sensitivity estimation and inverse problems in spatial stochastic models of chemical kinetics
    2015 (English)In: Numerical Mathematics and Advanced Applications: ENUMATH 2013, Springer, 2015, p. 519-527Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Springer, 2015
    Series
    Lecture Notes in Computational Science and Engineering ; 103
    National Category
    Computational Mathematics
    Identifiers
    urn:nbn:se:uu:diva-237184 (URN)10.1007/978-3-319-10705-9_51 (DOI)978-3-319-10704-2 (ISBN)
    Conference
    ENUMATH 2013
    Projects
    eSSENCEUPMARC
    Available from: 2014-10-31 Created: 2014-11-28 Last updated: 2018-11-12Bibliographically approved
    2. Multiscale modelling via split-step methods in neural firing
    Open this publication in new window or tab >>Multiscale modelling via split-step methods in neural firing
    2018 (English)In: Mathematical and Computer Modelling of Dynamical Systems, ISSN 1387-3954, E-ISSN 1744-5051, Vol. 24, p. 426-445Article in journal (Refereed) Published
    National Category
    Computational Mathematics Neurosciences
    Identifiers
    urn:nbn:se:uu:diva-332008 (URN)10.1080/13873954.2018.1488740 (DOI)000440605300005 ()
    Projects
    UPMARCeSSENCE
    Available from: 2018-08-01 Created: 2017-10-22 Last updated: 2018-11-19Bibliographically approved
    3. Fast event-based epidemiological simulations on national scales
    Open this publication in new window or tab >>Fast event-based epidemiological simulations on national scales
    2016 (English)In: The international journal of high performance computing applications, ISSN 1094-3420, E-ISSN 1741-2846, Vol. 30, p. 438-453Article in journal (Refereed) Published
    National Category
    Computer Sciences Computational Mathematics
    Identifiers
    urn:nbn:se:uu:diva-264751 (URN)10.1177/1094342016635723 (DOI)000387763100005 ()
    Projects
    UPMARCeSSENCE
    Available from: 2016-04-11 Created: 2015-10-16 Last updated: 2018-11-12Bibliographically approved
    4. Efficient inter-process synchronization for parallel discrete event simulation on multicores
    Open this publication in new window or tab >>Efficient inter-process synchronization for parallel discrete event simulation on multicores
    2015 (English)In: Proc. 3rd ACM SIGSIM Conference on Principles of Advanced Discrete Simulation, New York: ACM Press, 2015, p. 183-194Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    New York: ACM Press, 2015
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-260199 (URN)10.1145/2769458.2769476 (DOI)978-1-4503-3583-6 (ISBN)
    Conference
    SIGSIM-PADS 2015
    Projects
    UPMARC
    Available from: 2015-06-10 Created: 2015-08-17 Last updated: 2018-11-12Bibliographically approved
    5. Exposing inter-process information for efficient parallel discrete event simulation of spatial stochastic systems
    Open this publication in new window or tab >>Exposing inter-process information for efficient parallel discrete event simulation of spatial stochastic systems
    2017 (English)In: Proc. 5th ACM SIGSIM Conference on Principles of Advanced Discrete Simulation, New York: ACM Press, 2017, p. 53-64Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    New York: ACM Press, 2017
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-328367 (URN)10.1145/3064911.3064916 (DOI)978-1-4503-4489-0 (ISBN)
    Conference
    SIGSIM-PADS 2017
    Projects
    UPMARC
    Available from: 2017-05-16 Created: 2017-08-22 Last updated: 2018-11-12Bibliographically approved
  • 17.
    Beck, Daniel
    et al.
    University of Sheffield.
    Cohn, Trevor
    University of Melbourne.
    Hardmeier, Christian
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Languages, Department of Linguistics and Philology.
    Specia, Lucia
    University of Sheffield.
    Learning Structural Kernels for Natural Language Processing2015In: Transactions of the Association for Computational Linguistics, ISSN 2307-387X, Vol. 3, p. 461-473Article in journal (Refereed)
    Abstract [en]

    Structural kernels are a flexible learning paradigm that has been widely used in Natural Language Processing. However, the problem of model selection in kernel-based methods is usually overlooked. Previous approaches mostly rely on setting default values for kernel hyperparameters or using grid search, which is slow and coarse-grained. In contrast, Bayesian methods allow efficient model selection by maximizing the evidence on the training data through gradient-based methods. In this paper we show how to perform this in the context of structural kernels by using Gaussian Processes. Experimental results on tree kernels show that this procedure results in better prediction performance compared to hyperparameter optimization via grid search. The framework proposed in this paper can be adapted to other structures besides trees, e.g., strings and graphs, thereby extending the utility of kernel-based methods.

  • 18.
    Benedek, Nagy
    et al.
    University of Debrecen, Department of Computer Science, Debrecen Hungary .
    Strand, Robin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Normand, Nicolas
    Universit ́ de Nantes, IRCCyN UMR CNRS 6597, Nantes, France.
    A Weight Sequence Distance Function2013In: : Mathematical Morphology and Its Applications to Signal and Image Processing / [ed] Cris L. Luengo Hendriks, Gunilla Borgefors, Robin Strand, Springer Berlin/Heidelberg, 2013, p. 292-301Conference paper (Refereed)
    Abstract [en]

    In this paper, a family of weighted neighborhood sequence distance functions defined on the square grid is presented. With this distance function, the allowed weight between any two adjacent pixels along a path is given by a weight sequence. We build on our previous results, where only two or three unique weights are considered, and present a framework that allows any number of weights. We show that the rotational dependency can be very low when as few as three or four unique weights are used. An algorithm for computing the distance transform (DT) that can be used for image processing applications is also presented.

  • 19.
    Berglind, Jens
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Game Design.
    Choices and characters in roleplaying games: How types of choices affect the player/character connection2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The connection that players can feel toward their characters in pen-and-paper roleplaying games is a known phenomenon that has been previously studied and is recognized among roleplaying enthusiasts. Pen-and-paper roleplaying games are a complex form of games, with three distinct frames which are ludological, social, and diegetic (also called narrative). The frames are different aspects of the game as well as the base of different motivations for players, who value the frames in a varied degree. The goal of this thesis is to examine if in-game choices based on the diegetic frame in contrast to the ludological frame are correlated with the player/character connection.

    The method used for data collection is distribution of a quantitative questionnaire on the internet, spread to Swedish roleplayers through social media and associations tied to SVEROK. With their answers, the analysis identifies correlations between the player/character connection and the three frames of pen-and-paper roleplaying games, as well as other correlations noted in the data analysis. The literature revolves around the two core concepts; the player/character connection and the three frames of roleplaying games. The result shows that diegetic choices in contrast to ludological are weakly correlated with the player/character connection.

  • 20.
    Björck, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics.
    Creating Interactive Visualizations for Twitter Datasets using D32018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Project Meme Evolution Programme (Project MEP) is a research program directed by Raazesh Sainudiin, Uppsala University, Sweden, that collects and analyzes datasets from Twitter. Twitter can be used to understand how ideas spread in social media. This project aims to produce interactive visualizations for datasets collected in Project MEP. Such interactive visualizations will facilitate exploratory data analysis in Project MEP. Several technologies had to be learned to produce the visualizations, most notably JavaScript, D3, and Scala. Three interactive visualizations were produced; one that allows for exploration of a Twitter user timeline and two that allows for exploration and understanding of a Twitter retweet network. The interactive visualizations are accessible as Scala functions and in a website developed in this project and uploaded to GitHub. The interactive visulizations contain some known bugs but they still allow for useful exploratory data analysis of Project MEP datasets and the project goal is therefore considered met.

  • 21. Björk, Ingrid
    et al.
    Kavathatzopoulos, Iordanis
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Language and teaching ethics2018Conference paper (Refereed)
    Abstract [en]

    All problems with learning are increased when using English to teach non-English native students because of the culturally-sensitive nature of the subject of ethics. Coming to teaching ethics we are confronted with more difficulties. What is right and wrong is often affected by the culture, and different cultures often have different languages. Ethics theories are also expressed in language terms and they can be more easily misunderstood or misinterpreted compared to natural science theories. The feelings and every-day life encounters with “right” and “wrong” are linguistically experienced, described, and mediated. Therefore, language has a strong impact on whether something is ethical or whether it makes sense as an ethical issue at all.

  • 22.
    Björklund, Henrik
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Computing Science. Datalogi.
    Nilsson, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Computing Science. Datalogi.
    Svensson, Ola
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Computing Science. Datalogi.
    Vorobyov, Sergei
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Computing Science. Datalogi.
    Controlled Linear Programming: Boundedness and Duality2004Report (Other scientific)
    Abstract [en]

    Computer supported work is often stressful and inadequate computer sys-tems and poor usability contribute to the problem. Still the work situation, and work environment of users are seldom considered when developing computer systems, and it is difficult to incorporate the ideas of User Centred Systems Design (UCSD) in practice. Hence, this research addresses the dif-ficulty in integrating usability, UCSD and occupational health issues in IT systems development in order to improve the resulting work situation and well-being of users. How do basic values and perspectives of stakeholders in systems development projects affect the work with UCSD, usability and users’ health issues in the organisations studied?

    This research aims at influencing systems development in practice; hence, research is carried out in real life settings with an action research approach. Data is gathered and analysed with a qualitative research approach with in-terview studies, meetings with stakeholders, analysis of documentation, ob-servations and field studies. The theoretical framework adheres to situated action, participatory design, and UCSD that stresses the importance of in-volving users in the design process.

    This research shows that several basic values and perspectives affect sys-tems development and hinder the usability work, for example, the perspec-tive on user representatives, the value of rationality and objectivity, and the perspective underpinning descriptions and discourse on work. Moreover, this research indicates that the strong business values of automation, efficiency and customer satisfaction shape the development of new technology, and ultimately the tasks and work practices of the civil servants. In short, the studies show that there are some contradictions in business values and the implementation of user-centred systems design, usability and health issues in systems development.

    Attitudes and perspectives are not easily changed, and change comes gradually. In these organisations, we continuously discuss the integration of health issues in systems development, and by introducing and changing the models of systems development these will hopefully enable communication and change forwards of new perspectives and values. However, a focus on models alone is insufficient and therefore we need to develop a systematic approach to include reflection and new perspectives. Perhaps the reflection itself would help us see our values and perspectives and to alter them?

  • 23.
    Boman, Elvira
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Lugnegård, Lovisa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Kökollen2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The intention of this project was to develop an Android application, Kökollen, which would show ongoing events at Uppsala's student nations. The application would also show an estimated time for queuing.The events are uploaded by administrators (manly the nations) and thequeuing time is estimated by people standing in the queue reporting whenthey are entering and leaving the queue. The application is programmedin Java and XML. Kökollen is now uploaded on Google Play.

  • 24.
    Borgefors (editor), Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Short Descriptions of International Journals on Image Processing and its Applications2012Report (Other academic)
  • 25.
    Borgefors, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    ISMM 2013 - 11th International Symposium on Mathematical Morphology2013In: IAPR Newsletter, Vol. 35, no 4, p. 15-16Article in journal (Other (popular science, discussion, etc.))
  • 26.
    Borgefors, Gunilla
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Sarve, Hamid
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Johansson, Carina B
    Friberg, Bertil
    Osseointegration med hjälp av datoriserad bildanalys2012In: Tandläkartidningen, ISSN 0039-6982, Vol. 104, no 12, p. 66-71Article in journal (Refereed)
  • 27.
    Borgh, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems.
    Attribute-Based Encryption in Systems with Resource Constrained Devices in an Information Centric Networking Context2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An extensive analysis of attribute-based encryption (ABE) in systems with resource constrained devices is performed. Two system solutions of how ABE can be performed in such systems are proposed, one where the ABE operations are performed at the resource constrained devices and one where ABE is performed at a powerful server. The system solutions are discussed with three different ABE schemes. Two of the schemes are the traditional key policy ABE (KP-ABE) and ciphertext policy ABE (CP-ABE). The third scheme is using KP-ABE to simulate CP-ABE, in an attempt to benefit from KP-ABE being computationally cheaper than CP-ABE while maintaining the intuitive way of using CP-ABE.

    ABE is a computationally expensive encryption method which might not be feasible to perform at the resource constrained sensors, depending on the hardware.

    An implementation of a CP-ABE scheme with a 128 bit security level was written and used to evaluate the feasibility of ABE on a sensor equipped with an ARM Cortex-M3 processor having 32 kB RAM and 256 kB flash. It is possible to perform CP-ABE on the sensor used in this project. The limiting factor of feasibility of ABE on the sensor is the RAM size. In this case policy sizes up to 12 attributes can be performed on the sensor.

    The results give an idea of the feasibility of encryption with ABE on sensors. In addition to the results several ways of improving performance of ABE on the sensor are discussed.

  • 28.
    Carlsson, Martin
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Game Design.
    Automatic Code Generation from a Colored Petri Net Specification for Game Development with Unity3D2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis proposes an approach for automatic code generation from a Colored Petri net specification. Two tools were developed for the aforementioned purpose, a Colored Petri net editor to create and modify Colored Petri nets, and an automatic code generator to generate code from a Colored Petri net specification. Through the use of the editor four models were created, these models were used as input to the automatic code generator. The automatic code generator successfully generated code from the Colored Petri net specification, code in the form of component scripts for the Unity3D game engine. However, the approach used by the code generator had flaws such as introducing overhead in the generated code, failing to deal with concurrency, and restricting the types of Colored Petri nets which could be used as input. The aforementioned tools could be used in the future to research the benefits and disadvantages of modeling game systems with Colored Petri nets, and automatically generating code from Colored Petri nets.

  • 29.
    Carpentier, Nico
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Informatics and Media.
    Além da escada da participação: Ferramentas analíticas para a análise crítica dos processos midiáticos participativos2018In: Mídia e Cotidiano, Revista do Programa de Pós-Graduação em Mídia e Cotidiano, ISSN 2178-602X, Vol. 12, no 3, p. 245-274Article in journal (Refereed)
    Abstract [en]

    Participatory research is facing three challenges—how to deal with the theoretisation and conceptualisation of participation; how to support the research with analytical models; and how the evaluate the research outcomes. This article aims to address these three problems by distinguishing two main approaches (a sociological and a political) in participatory theory and developing a four-level and 12-step analytical model that functions within the political approach. In this analytical model, a series of key concepts are used: process, field, actor, decision-making moment and power. The normative-evaluative problem is addressed by reverting to the critical perspective to evaluate the societal desirability of particular participatory intensities. This critical perspective—potentially—adds a 13th and final normative layer to the analytical model.

  • 30.
    Cheung, Ricky
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction.
    Stochastic based football simulation using data2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis is an extension of a football simulator made in a previous project, where we also made different visualizations and simulators based on football data. The goal is to create a football simulator based on a modified Markov chain process, where two teams can be chosen, to simulate entire football matches play-by-play. To validate our model, we compare simulated data with the provided data from Opta. Several adjustments are made to make the simulation as realistic as possible. After conducting a few experiments to compare simulated data with real data before and after adjustments, we conclude that the model may not be adequately accurate to reflect real life matches.

  • 31. Commer, Michael
    et al.
    Maia, Filipe R. N. C.
    National Energy Research Scientific Computing Center, Lawrence Berkeley National Laboratory, Berkeley, USA .
    Newman, Gregory A.
    Iterative Krylov solution methods for geophysical electromagnetic simulations on throughput-oriented processing units2012In: The international journal of high performance computing applications, ISSN 1094-3420, E-ISSN 1741-2846, Vol. 26, no 4, p. 378-385Article in journal (Refereed)
    Abstract [en]

    Many geo-scientific applications involve boundary value problems arising in simulating electrostatic and electromagnetic fields for geophysical prospecting and subsurface imaging of electrical resistivity. Modeling complex geological media with three-dimensional finite-difference grids gives rise to large sparse linear systems of equations. For such systems, we have implemented three common iterative Krylov solution methods on graphics processing units and compared their performance with parallel host-based versions. The benchmarks show that the device efficiency improves with increasing grid sizes. Limitations are currently given by the device memory resources.

  • 32.
    Conze, Ronald
    et al.
    GFZ German Research Centre for Geosciences: Potsdam, Germany .
    Lorenz, Henning
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Ulbricht, Damian
    GFZ German Research Centre for Geosciences: Potsdam, Germany .
    Elger, Kirsten
    GFZ German Research Centre for Geosciences: Potsdam, Germany .
    Gorgas, Thomas
    GFZ German Research Centre for Geosciences: Potsdam, Germany .
    Utilizing the International Geo Sample Number Concept in Continental Scientific Drilling During ICDP Expedition COSC-12017In: Data Science Journal, ISSN 1683-1470, E-ISSN 1683-1470, Vol. 1, no 1, p. 1-8, article id 16:2Article in journal (Refereed)
    Abstract [en]

    The International Geo Sample Number (IGSN) is a globally unique persistent identifier (PID) for physical samples that provides discovery functionality of digital sample descriptions via the internet. In this article we describe the implementation of a registration service for IGSNs of the Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences. This includes the adaption of the metadata schema developed within the context of the System for Earth Sample Registration (SESAR1) to better describe the complex sample hierarchy of drilling cores, core sections and samples of scientific drilling projects. Our case study is the COSC-1 expedition2 (Collisional Orogeny in the Scandinavian Caledonides) supported by the International Continental Scientific Drilling Program3 (ICDP). COSC-1 prompted for the first time in ICDP’s history to assign and register IGSNs during an on-going drilling campaign preserving the original parent-child relationship of the sample objects. IGSN-associated data and metadata are distributed and shared with the world wide community through novel web portals, one of which is currently evolving as part of ICDP’s collaborative efforts within the GFZ Potsdam and researchers from ICDP’s COSC clientele. Thus, COSC-1 can be considered as a ‘Prime-Example’ for ICDP projects to further improve the quality of scientific research output through a transparent process of producing and managing large quantities of data as they are normally acquired during a typical scientific drilling operation. The IGSN is an important new player in the general publication landscape that can be cited in scholarly literature and also cross-referenced in DOI-bearing scholarly and data publications.

  • 33. Coufalova, Eva
    et al.
    Mynar, Martin
    Drsticka, Michal
    Stepan, Petr
    Sintorn, Ida-Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Low Voltage Mini TEM2014In: Proceedings, 2014Conference paper (Other academic)
  • 34.
    Curic, Vladimir
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction.
    Hendriks Luengo, Cris L.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Adaptive structuring elements based on salience information2012In: Computer Vision and Graphics / [ed] L. Bolc, K. Wojciechowski, R. Tadeusiewicz, L.J. Chmielewski, Springer, 2012, p. 321-328Conference paper (Other academic)
    Abstract [en]

    Adaptive structuring elements modify their shape and size according to the image content and may outperform fixed structuring elements. Without any restrictions, they suffer from a high computational complexity, which is often higher than linear with respect to the number of pixels in the image. This paper introduces adaptive structuring elements that have predefined shape, but where the size is adjusted to the local image structures. The size of adaptive structuring elements is determined by the salience map that corresponds to the salience of the edges in the image, which can be computed in linear time. We illustrate the difference between the new adaptive structuring elements and morphological amoebas. As an example of its usefulness, we show how the new adaptive morphological operations can isolate the text in historical documents.

  • 35. Dahlqvist, Bengt
    FEXPAC - A Program for Linear Discriminant Classification1988In: Computer Programs in Biomedicine, ISSN 0010-468X, no 26, p. 199-206Article in journal (Refereed)
  • 36.
    Dahlqvist, Bengt
    Uppsala University.
    Procedures for Computer-Assisted Data Plotting1984Report (Other academic)
  • 37.
    Dahlqvist, Bengt
    et al.
    Uppsala University.
    Nordin, Bo
    Uppsala University.
    En undersökning av några på cellnivå kvantifierbara visuella indikatorers diagnosvärde vid förekomsten av livmoderhalscancer1998Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 38.
    Edvinsson, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Implementing the circularly polarized light method for determining wall thickness of cellulosic fibres2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The wall thickness of pulp fibers plays a major role in the paper industry, but it is currently not possible to measure this property without manual laboratory work. In 2007, researcher Ho Fan Jang patented a technique to automatically measure fiber wall thickness, combining the unique optical properties of pulp fibers with image analysis. In short, the method creates images through the use of an optical system resulting in color values which demonstrate the retardation of a particular wave length instead of the intensity. A device based on this patent has since been developed by Eurocon Analyzer. This thesis investigates the software aspects of this technique, using sample images generated by the Eurocon Analyzer prototype.

    The software developed in this thesis has been subdivided into three groups for independent consideration. First being the problem of solving wall thickness for colors in the images. Secondly, the image analysis process of identifying fibers and good points for measuring them. Lastly, it is investigated how statistical analysis can be applied to improve results and derive other useful properties such as fiber coarseness.

    With the use of this technique there are several problems which need to be overcome. One such problem is that it may be difficult to disambiguate the colors produced by fibers of different thickness. This complication may be reduced by using image analysis and statistical analysis. Another challenge can be that theoretical values often differ greatly from the observed values which makes the computational aspect of the method problematic. The results of this thesis show that the effects of these problems can be greatly reduced and that the method offers promising results.

    The results clearly distinguish between and show the expected characteristics of different pulp samples, but more qualitative reference measurements are needed in order to draw conclusions on the correctness of the results.

  • 39.
    Eklund, Joakim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Isaksson, Fred
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control.
    Identifying & Evaluating SystemComponents for Cognitive Trustin AI-Automated Service Encounters: Trusting a Study- & Vocational Chatbot2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The intensifying idea that AI soon will be a part of our everyday life allows for dreams about the complex relationship we one day could have with non-biological social intelligence. However, establishing societal and individual acceptance of AI-powered autonomy in disciplines built upon to the reliance to human competence raises a number of pressing challenges. One of them being, what system components will engender respectively counteract cognitive trust in socially oriented AI-automated processes?  

    This masters thesis tackles the seemingly ambiguous concept of trust in automation by identifying and evaluating system components that affect trust in a confined and contextualised setting. Practically, we design, construct and test an AI-powered chatbot, Ava, that contains socially oriented questions and feedback about study- and vocational guidance. Through a comparative study of different system versions, including both quantitative and qualitative data, we contribute to the framework for identifying and evaluating human trust in AI-Automated service encounters. We show how targeted alterations to design choices constituting the system components transparency, unbiasses and system performance, identified to affect trust, has consequences on the perception of the cognitive trust concepts integrity, benevolence and ability. Our results display a way of conduct for practitioners looking to prioritise and develop trustworthy autonomy. More specifically, we account for how cognitive trust is decreased when system opacity is increased. Moreover, we display even more concerning effects on trust due to micking contextual bias in the conversation agent.

  • 40.
    Enander, Filippa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics.
    Klusteranalys inom området skatteplaneringsaktiva företag2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the Swedish Tax Agency’s possibilities to use data mining techniques to support tax inspection case-selection within the business sector. The purpose of the study was based on a hypothesis by the Swedish Tax Agency regarding accounting similarities among prosecuted businesses (for abusive tax planning activities). The aim was to examine if statistical cluster analyses could be used to identify homogeneous groups and if the hypothesis about internal similarities could be strengthened. If such groups could be generated, other businesses within the same groups would be of interest for control. Clustering algorithms were applied to tax data from approximately 580 000 Swedish businesses along with data from 658 completed tax audits. The cluster approach was followed up by a multivariate outlier analysis to further examine potential similarities between the tax planning businesses. The best clustering results were generated by K-means clustering and consisted of a cluster with 5 % (323 businesses) of abusive tax planning businesses. Clustering applied on the data used in this study did not strengthen the hypothesis concerning internal similarities. Contrary to the hypothesis, businesses prosecuted for abusive tax planning activities displayed greater internal differences than other businesses. Similarity patterns could better be identified through outlier analysis, where 90% of said businesses were singled-out among the 10% most extreme observations. This study primarily concludes that the use of cluster analyses on the given data is not an efficient tax auditing selection method and that improved data quality is required to obtain more accurate results.

  • 41.
    Eriksson, Robin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Bayesian Parameterization in the spread of Diseases2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mathematical and computational epidemiological models are important tools in efforts to combat the spread of infectious diseases. The models can be used to predict further progression of an epidemic and for assessing potential countermeasures to control disease spread. In the proposal of models (when data is available), one needs parameter estimation methods. In this thesis, likelihood-less Bayesian inference methods are concerned. The data and the model originate from the spread of a verotoxigenic Escherichia coli in the Swedish cattle population. In using the SISE3 model, which is an extension of the susceptible-infected-susceptible model with added environmental pressure and three age categories, two different methods were employed to give an estimated posterior: Approximate Bayesian Computations and Synthetic Likelihood Markov chain Monte Carlo. The mean values of the resulting posteriors were close to the previously performed point estimates, which gives the conclusion that Bayesian inference on a nation scaled SIS-like network is conceivable.

  • 42.
    Eriksson, Robin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Stencil Study for RBF-FD in Option Pricing2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis contains results on convergence studies for different stencils of radial basis function generated finite difference (RBF-FD) method applied to solving Black-Scholes equation for pricing European call options. The results experimentally confirm the theoretical convergence rates for smooth payoff functions with stencils of size 3, 5 and 7 in one- dimensional problems, and 9, 13 and 25 in two- dimensional problems. Moreover, it is shown how different terms in the equation can be approximated individually using the proposed method and then combined into a discrete approximation of the entire spatial differential operator. This new version of the RBF-FD method, where each term has been

    approximated individually, has been compared to the classical method and the outcome did not show any significant performance advantages. Nevertheless, the results also showed that the second order derivative was the hardest one to approximate accurately and this poses an important finding for the future development of the method. 

  • 43. Ersson, Kerstin
    et al.
    Siri, Persson
    Peer-to-peer distribution of web content using WebRTC within a web browser2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this project was to investigate if it is possible to host websites using the BitTorrent protocol, a protocol for distribution of data on the web. This was done using several Node.js modules, small clusters of code written in JavaScript, such as Browserify and a modified version of WebTorrent. In these modules, technologies like websockets and WebRTC are implemented. The project resulted in a working WebTorrent module, implemented on the website www.peerweb.io. However, the module still needs optimization concerning the time it takes to set up a WebRTC peer connection. With these modifications, we believe that hosting websites via peer-to-peer network will be the future of the web.

  • 44. Estevez, B.
    et al.
    Pazos, M.
    Franco, J. M.
    Hast, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Recreating with photogrammetric techniques a submerged megalithic landscape: the case of the salas reservoir2015In: 3 Encontro Internacional de Arqueoloxia de Vilalba, 2015, p. 9-16Conference paper (Refereed)
  • 45.
    Fatemi, Zahra
    et al.
    Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran.
    Magnani, Matteo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Salehi, Mostafa
    Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran.
    A generalized force-directed layout for multiplex sociograms2018In: Social Informatics: 10th International Conference, SocInfo 2018, St. Petersburg, Russia, September 25-28, 2018, Proceedings, Part I, Springer, 2018, Vol. 11185, p. 212-227Conference paper (Refereed)
    Abstract [en]

    Multiplex networks are defined by the presence of multiple edge types. As a consequence, it is hard to produce a single visualization of a network revealing both the structure of each edge type and their mutual relationships: multiple visualization strategies are possible, depending on how each edge type should influence the position of the nodes in the sociogram. In this paper we introduce multiforce, a force-directed layout for multiplex networks where both intra-layer and inter-layer relationships among nodes are used to compute node coordinates. Despite its simplicity, our algorithm can reproduce the main existing approaches to draw multiplex sociograms, and also supports a new intermediate type of layout. Our experiments on real data show that multiforce enables layered visualizations where each layer represents an edge type, nodes are well aligned across layers and the internal layout of each layer highlights the structure of the corresponding edge type.

  • 46. Fuller, Ursula
    et al.
    Pears, Arnold
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Datorteknik.
    Amillo, June
    Avram, Chris
    Mannila, Linda
    A Computing Perspective on the Bologna Process2006In: SIGCSE Bulletin: inroads, ISSN 0097-8418, Vol. 38, no 4, p. 115-131Article in journal (Refereed)
    Abstract [en]

    The Bologna process is intended to culminate in the formation of the European Higher Education Area (EHEA) by 2010. Its aim is to facilitate the mobility of people, the transparency and recognition of qualifications, quality and development of a European dimension to higher education, and the attractiveness of European institutions for third country students.

    This paper provides an overview of progress towards implementation in EHEA member states using official documents and interview data from faculty teaching computing in countries represented at the ITiCSE 2006 meeting. The key areas where the structures established by the Bologna process are problematic for computing education arise from the rapidly changing nature of the curriculum. It seems that the maturity and capability criteria, as well as the manner in which learning outcomes are specified, being developed within the Bologna process are too general. This endangers the properties of transparency and mobility that the process intends to promote.

    Progression and prerequisite knowledge in computing degrees can be very specific. For instance, generic learning outcomes for an introductory programming course quite rightly will not specify the programming language, or languages, used to implement algorithms. However, suppose a student intends to study an advanced algorithms and data structures course in which Java is the language of implementation which has an introductory course in programming as a prerequisite. If the introductory course language was Standard ML it is not clear that the prerequisite course actually provides the student with a suitable background. These types of complexities are typical of computing, where early subject curricula are not standardised nationally or internationally, and create significant hurdles for realising the Bologna objectives.

  • 47.
    Gustavsson, Kenneth
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Bengtsson Bernander, Karl
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Stochastic Watershed: A Comparison of Different Seeding Methods2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    We study modifications to the novel stochastic watershed method for segmentation of digital images. This is a stochastic version of the original watershed method which is repeatedly realized in order to create a probability density function for the segmentation. The study is primarily done on synthetic images with both same-sized regions and differently sized regions, and at the end we apply our methods on two endothelial cell images of the human cornea. We find that, for same-sized regions, the seeds should be placed in a spaced grid instead of a random uniform distribution in order to yield a more accurate segmentation. When images with differently sized regions are being segmented, the seeds should be placed dependent on the gradient, and by also adding uniform or gaussian noise to the image in every iteration a satisfactory result is obtained.

  • 48.
    Hagström, Josefin
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Winman, Anders
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Virtually overcoming grammar learning with 3D application of Loci mnemonics?2018In: Applied Cognitive Psychology, ISSN 0888-4080, E-ISSN 1099-0720, Vol. 32, no 4, p. 450-462Article in journal (Refereed)
  • 49.
    Hanteer, Obaida
    et al.
    IT University Of Copenhagen, DssLab, Denmark.
    Rossi, Luca
    IT University Of Copenhagen, DssLab, Denmark.
    Vega, Davide
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Magnani, Matteo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    From Interaction to Participation: The Role of the Imagined Audience in Social Media Community Detection and an Application to Political Communication on Twitter2018In: 2018 IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining (ASONAM), IEEE Computer Society , 2018, p. 531-534Conference paper (Refereed)
    Abstract [en]

    In the context of community detection in online social media, a lot of effort has been put into the definition of sophisticated network clustering algorithms and much less on the equally crucial process of obtaining high-quality input data. User-interaction data explicitly provided by social media platforms has largely been used as the main source of data because of its easy accessibility. However, this data does not capture a fundamental and much more frequent type of participatory behavior where users do not explicitly mention others but direct their messages to an invisible audience following a common hashtag. In the context of multiplex community detection, we show how to construct an additional data layer about user participation not relying on explicit interactions between users, and how this layer can be used to find different types of communities in the context of Twitter political communication.

  • 50.
    Hast, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Centre for Image Analysis. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis.
    Europar 2010, Parallel Processing Workshops: UCHPC2010.2010Conference proceedings (editor) (Refereed)
123 1 - 50 of 135
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