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  • 1.
    Andersson, Rickard
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Pseudo-optimal strategies in no-limit poker2006In: ICGA Journal, ISSN 1389-6911, Vol. 29, no 3, p. 143-149Article in journal (Refereed)
    Abstract [en]

    Games have always been a strong driving force in Artificial Intelligence. In the last ten years huge improvements has been made in perfect information games like chess and Othello. The strongest computer agents can nowadays beat the strongest human players. This is not the case for imperfect information games such as poker and bridge where creating an expert computer player has shown to be much harder. Previous research in poker has either addressed limit poker or simplified variations of poker games. This paper tries to extend known techniques successfully used in limit poker to no-limit. No-limit poker increases the size of the game tree drastically. To reduce the complexity an abstracted model of the game is created. Finding an optimal strategy for the new model is now a minimization problem using linear programming techniques. The result is a set of pseudo-optimal strategies for no-limit Texas Hold'em. A bot named AGGROBOT was built from these strategies which perform well as long as the players' stack sizes are fairly small.

  • 2. Backman, Anders
    et al.
    Bodin, Kenneth
    Umeå University, Faculty of Science and Technology, High Performance Computing Center North (HPC2N).
    Lacoursière, Claude
    Umeå University, Faculty of Science and Technology, High Performance Computing Center North (HPC2N).
    Servin, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Democratizing CAE with Interactive Multiphysics Simulation and Simulators2012Conference paper (Other academic)
  • 3.
    Billing, Erik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Servin, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Composer: A prototype multilingual model composition tool2013In: MODPROD2013: 7th MODPROD Workshop on Model-Based Product Development / [ed] Peter Fritzson, Umeå: Umeå universitet , 2013Conference paper (Other academic)
    Abstract [en]

    Composer - A prototype multilingual model composition tool

    Erik Billing and Martin Servin

    November 10, 2012

    Facing the task to design, simulate or optimize a complex system itis common to find models and data for the system expressed in differentformats, implemented in different simulation software tools. When a newmodel is developed, a target platform is chosen and existing componentsimplemented with different tools have to be converted. This results inunnecessary work duplication and lead times. The Modelica languageinitiative [2] partially solves this by allowing developers to move modelsbetween different tools following the Modelica standard. Another possi-bility is to exchange models using the Functional Mockup Interface (FMI)standard that allows computer models to be used as components in othersimulations, possibly implemented using other programming languages[1]. With the Modelica and FMI standards entering development, there isneed for an easy-to-use tool that supports design, editing and simulationof such multilingual systems, as well as for retracting system informationfor formulating and solving optimization problems.A prototype solution for a graphical block diagram tool for design, edit-ing, simulation and optimization of multilingual systems has been createdand evaluated for a specific system. The tool is named Composer [3].The block diagram representation should be generic, independent ofmodel implementations, have a standardized format and yet support effi-cient handling of complex data. It is natural to look for solutions amongmodern web technologies, specifically HTML5. The format for represent-ing two dimensional vector graphics in HTML5 is Scalable Vector Graphics(SVG). We combine the SVG format with the FMI standard. In a firststage, we take the XML-based model description of FMI as a form for de-scribing the interface for each component, in a language independent way.Simulation parameters can also be expressed on this form, and integratedas metadata into the SVG image. 

    The prototype, using SVG in conjunction with FMI, is implementedin JavaScript and allow creation and modification of block diagrams directly in the web browser. Generated SVG images are sent to the serverwhere they are translated to program code, allowing the simulation ofthe dynamical system to be executed using selected implementations. Analternative mode is to generate optimization problem from the systemdefinition and model parameters. The simulation/optimization result is 

    returned to the web browser where it is plotted or processed using otherstandard libraries.The fiber production process at SCA Packaging Obbola [4] is used asan example system and modeled using Composer. The system consists oftwo fiber production lines that produce fiber going to a storage tank [5].The paper machine is taking fiber from the tank as needed for production.A lot of power is required during fiber production and the purpose of themodel was to investigate weather electricity costs could be reduced byrescheduling fiber production over the day, in accordance with the electricity spot price. Components are implemented for dynamical simulationusing OpenModelica and for discrete event using Python. The Python implementation supports constraint propagation between components andoptimization over specified variables. Each component is interfaced as aFunctional Mock-up Unit (FMU), allowing components to be connectedand properties specified in language independent way. From the SVGcontaining the high-level system information, both Modelica and Pythoncode is generated and executed on the web server, potentially hosted ina high performance data center. More implementations could be addedwithout modifying the SVG system description.We have shown that it is possible to separate system descriptions onthe block diagram level from implementations and interface between thetwo levels using FMI. In a continuation of this project, we aim to integratethe FMI standard also for co-simulation, such that components implemented in different languages could be used together. One open questionis to what extent FMUs of the same component, but implemented withdifferent tools, will have the same model description. For the SVG-basedsystem description to be useful, the FMI model description must remainthe same, or at least contain a large overlap, for a single component implemented in different languages. This will be further investigated in futurework.

    References

    [1] Modelica Association. Functional mock-up interface, http://www.fmi-standard.org, November 2012.

    [2] Modelica Association. Modelica and the modelica association, http://www.modelica.org, November 2012.

    [3] Erik Billing and Martin Servin. Composer, http://imuit.cs.umu.se/composer, November 2012. [4] SCA Packaging. Sca packaging obbola, http://www.scapackaging.com, November 2012.

    [5] Patrik Törmänen and Hussein Jaffal. Reducing electricity cost - case study. Technical report, UMIT Research Lab, Umeå University, 2011.2

  • 4.
    Buckland, Philip I.
    et al.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Eriksson, Erik J.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Palm, Fredrik
    Umeå University, Faculty of Arts, Humlab.
    SEAD - The Strategic Environmental Archaeology Database: Progress Report Spring 20142014Report (Other academic)
    Abstract [en]

    This report provides an overview of the progress and results of the VR:KFI infrastructure projects 2007-7494 and (825-)2010-5976. It should be considered as a status report in an on-going long-term research infrastructure development project.

  • 5.
    Börstler, Jurgen
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Christensen, Henrik B
    Nordström, Marie
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Kallin Westin, Lena
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Moström, Jan Erik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Caspersen, Michael E
    Evaluating OO Example Programs for CS12008In: Proceedings of the 13th annual conference on Innovation and technology in computer science education, 2008, p. 47-52Conference paper (Refereed)
  • 6.
    Börstler, Jürgen
    Umeå University, Faculty of Science and Technology.
    Using Role-Play Diagrams to Improve Scenario Role-Play2010In: Graph Transformations and Model-Driven Engineering: Essays Dedicated to Manfred Nagl on the Occasion of his 65th Birthday / [ed] Gregor Engels, Claus Lewerentz, Wilhelm Schäfer, Andy Schürr, Bernhard Westfechtel, Springer Berlin/Heidelberg, 2010, p. 309-334Chapter in book (Refereed)
    Abstract [en]

    CRC-cards are a common lightweight approach to collaborative object-oriented analysis and design. They have been adopted by many educators and trainers to teach object-oriented modelling. In our experience, we have noticed many subtle problems and issues that have largely gone unnoticed in the literature. Two of the major issues are related to the CRC-card role-play as described in the literature. Although CRC-cards are representing classes, they are also utilized as substitutes for the actual objects during the scenario role-play. Furthermore; it is quite difficult to document or trace the scenario role-play. We propose using Role-Play Diagrams (RPDs) to overcome these problems. Our experience so far is quite positive. Novices have fewer problems with role-play activities when using these diagrams. Teaching and learning the new type of diagram adds only little overhead to the overall CRC-approach. Although our improvements specifically target the teaching and learning of object-oriented modelling, we believe that RPDs can be successfully applied in professional software development.

  • 7.
    Börstler, Jürgen
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Nordström, Marie
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Kallin Westin, Lena
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Moström, Jan Erik
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Christensen, Henrik B.
    Bennedsen, Jens
    An Evaluation Instrument for Object-Oriented Example Programs for Novices2008Report (Other academic)
  • 8.
    Chaudhry, Tanmay
    et al.
    SimScale GmbH, Germany.
    Doblander, Christoph
    Technische Universität München, Germany.
    Dammer, Anatol
    SimScale GmbH, Germany.
    Klein, Cristian
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Jacobsen, Hans-Arno
    Technische Universität München, Germany.
    Retrofitting Admission Control in an Internet-Scale Application2016Report (Other academic)
    Abstract [en]

    In this paper we propose a methodology to retrofit admission control in an Internet-scale, production application. Admission control requires less effort to improve the availability of an application, in particular when making it scalable is costly. This can occur due to the integration of 3rd-party legacy code or handling large amounts of data, and is further motivated by lean thinking, which argues for building a minimum viable product to discover customer requirements.

    Our main contribution consists in a method to generate an amplified workload, that is realistic enough to test all kinds of what-if scenarios, but does not require an exhaustive transition matrix. This workload generator can then be used to iteratively stress-test the application, identify the next bottleneck and add admission control.

    To illustrate the usefulness of the approach, we report on our experience with adding admission control within SimScale, a Software-as-a-Service start-up for engineering simulations, that already features 50,000 users.

  • 9. Chaudhry, Tanmay
    et al.
    Doblander, Christoph
    Dammer, Anatol
    Klein, Cristian
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Jacobsen, Hans-Arno
    Retrofitting Admission Control in an Internet-Scale Application2016Report (Other academic)
    Abstract [en]

    In this paper we propose a methodology to retrofit admission control in an Internet-scale, production application. Admission control requires less effort to improve the availability of an application, in particular when making it scalable is costly. This can occur due to the integration of 3rd-party legacy code or handling large amounts of data, and is further motivated by lean thinking, which argues for building a minimum viable product to discover customer requirements.

    Our main contribution consists in a method to generate an amplified workload, that is realistic enough to test all kinds of what-if scenarios, but does not require an exhaustive transition matrix. This workload generator can then be used to iteratively stress-test the application, identify the next bottleneck and add admission control.

    To illustrate the usefulness of the approach, we report on our experience with adding admission control within SimScale, a Software-as-a-Service start-up for engineering simulations, that already features 50,000 users.

  • 10.
    Eriksson, Magnus
    Umeå University, Faculty of Science and Technology, Computing Science.
    An approach to software product line use case modeling2006Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Organizations developing software intensive defense systems are today faced with a number challenges related to characteristics of both the market place and the system domain:

    1. Systems grow ever more complex, consisting of tightly integrated mechanical, electrical/electronic and software components.

    2. Systems are often developed in short series; ranging from only a few to a few hundred units.

    3. Systems have very long life spans, typically 30 years or longer.

    4. Systems are developed with high commonality between different customers; however systems are always customized for specific needs.

    The goal of the research presented in this thesis is to investigate methods and tools to enable efficient development and maintenance of systems in such a context. The strategy adopted in this work is to utilize the forth system characteristic, high commonality, to achieve this.

    One approach to software reuse, which could be a potential solution as it enables reuse of common parts but at the same time allow for variations, is known as software product line development. The basic idea of this approach is to use domain knowledge to identify common parts within a family of related products and to separate them from the differences between the products. The commonalties are then used to create a product platform that can be used as a common baseline for all products within such a product family.

    The main contribution of this licentiate thesis is a product line use case modeling approach tailored towards organizations developing software intensive defense systems. We describe how a common and complete use case model can be developed and maintained for a whole family of products, and how the variations within such a family are modeled using a feature model. Concrete use case models, for particular products within a family, can then be generated by selecting features from a feature model. We furthermore describe extensions to the commercial requirements management tool Telelogic DOORS and the UML modeling tool IBM-Rational Rose to support the proposed approach.

    The approach was applied and evaluated in an industrial case study in the target domain. Based on the collected case study data we draw the conclusion that the approach performs better than modeling according to the styles and guidelines specified by the IBM-Rational Unified Process (RUP) in the current industrial context. The results however also indicate that for the approach to be successfully applied, stronger configuration management and product planning functions than traditionally found in RUP projects are needed.

  • 11. Filieri, Antonio
    et al.
    Maggio, Martina
    Angelopoulos, Konstantinos
    D’ippolito, Nicolás
    Gerostathopoulos, Ilias
    Hempel, Andreas Berndt
    Hoffmann, Henry
    Jamshidi, Pooyan
    Kalyvianaki, Evangelia
    Klein, Cristian
    Krikava, Filip
    Misailovic, Sasa
    Papadopoulos, Alessandro Vittorio
    Lund University, Sweden.
    Ray, Suprio
    Sharifloo, Amir M.
    Shevtsov, Stepan
    Ujma, Mateusz
    Vogel, Thomas
    Control Strategies for Self-Adaptive Software Systems2017In: ACM Transactions on Autonomous and Adaptive Systems, ISSN 1556-4665, E-ISSN 1556-4703, Vol. 11, no 4, article id 24Article in journal (Refereed)
    Abstract [en]

    The pervasiveness and growing complexity of software systems are challenging software engineering to design systems that can adapt their behavior to withstand unpredictable, uncertain, and continuously changing execution environments. Control theoretical adaptation mechanisms have received growing interest from the software engineering community in the last few years for their mathematical grounding, allowing formal guarantees on the behavior of the controlled systems. However, most of these mechanisms are tailored to specific applications and can hardly be generalized into broadly applicable software design and development processes.

    This article discusses a reference control design process, from goal identification to the verification and validation of the controlled system. A taxonomy of the main control strategies is introduced, analyzing their applicability to software adaptation for both functional and nonfunctional goals. A brief extract on how to deal with uncertainty complements the discussion. Finally, the article highlights a set of open challenges, both for the software engineering and the control theory research communities.

  • 12. Führer, Claus
    et al.
    Solem, Jan-Erik
    Verdier, Olivier
    Computing with Python: An introduction to Python for science and engineering2014Book (Refereed)
  • 13. Führer, Claus
    et al.
    Solem, Jan-Erik
    Verdier, Olivier
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Computing with Python: An introduction to Python for science and engineering2013Book (Refereed)
  • 14.
    Granat, Robert
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science. Umeå University, Faculty of Science and Technology, High Performance Computing Center North (HPC2N).
    Kågström, Bo
    Umeå University, Faculty of Science and Technology, Department of Computing Science. Umeå University, Faculty of Science and Technology, High Performance Computing Center North (HPC2N).
    Kressner, Daniel
    ETH, Zürich.
    Parallel Eigenvalue Reordering in Real Schur Forms2009In: Concurrency and Computation, ISSN 1532-0626, E-ISSN 1532-0634, Vol. 21, no 9, p. 1225-1250Article in journal (Refereed)
    Abstract [en]

    A parallel algorithm for reordering the eigenvalues in the real Schur form of a matrix is presented and discussed. Our novel approach adopts computational windows and delays multiple outside-window updates until each window has been completely reordered locally. By using multiple concurrent windows the parallel algorithm has a high level of concurrency, and most work is level 3 BLAS operations. The presented algorithm is also extended to the generalized real Schur form. Experimental results for ScaLAPACK-style Fortran 77 implementations on a Linux cluster confirm the efficiency and scalability of our algorithms in terms of more than 16 times of parallel speedup using 64 processors for large-scale problems. Even on a single processor our implementation is demonstrated to perform significantly better compared with the state-of-the-art serial implementation.

  • 15.
    Granberg, Tony
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Mjukvara för träning av routersyntax2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report explains the implementation and purpose for the computer software called Routersyntax that aims to assist students in exercising router command syntax. Written in Python, the software uses a simplistic command line-driven user interface, designed specifically for routing administration training. The software is divided into two parts: a client and a server. Using the router syntax software, users get an opportunity to try to improve their skills in administering router hardware by exercising router command input in an environment which is free to use for students. The aim is for the software to require nothing but Python and a Python-compatible operating system to run. It supports Windows, Ubuntu Linux and OS X out of the box.

  • 16.
    Hegner, Stephen
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Internal representation of database views2010In: Journal of universal computer science (Online), ISSN 0948-695X, E-ISSN 0948-6968, Vol. 16, no 20, p. 2956-2985Article in journal (Refereed)
    Abstract [en]

    Although a database view embodies partial information about the state of the main schema, the state of the view schema is a quotient (and not a subset) of the state of the main schema. It is the information content of the view state, the set of sentences which are true for that state, and not the state itself which is a subset of the information content of the state of the main schema. There are thus two dual approaches to modelling this partiality, one based upon structures, with a consequent quotient relationship, and another based upon logical theories, with a consequent subset relationship. In this work, a representation for database views is developed which combines these two approaches. The state-based representation is expanded so that the information content embodied in a wide class of views, including those defined by SPJ queries, is fully representable, thus permitting the view state to be modelled internally as a subset of the main database state. The utility of this framework is demonstrated with a simple solution to the uniqueness problem for view updates via constant complement.

  • 17.
    Johansson, Pedher
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Matrix canonical structure toolbox2006Report (Other (popular science, discussion, etc.))
  • 18.
    Johansson, Pedher
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    StratiGraph developer's guide2006Report (Other academic)
  • 19.
    Johansson, Pedher
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    StratiGraph software design and algorithms2006Report (Other (popular science, discussion, etc.))
  • 20.
    Johansson, Pedher
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    StratiGraph user's guide2003Report (Other academic)
  • 21.
    Loconsole, Annabella
    Umeå University, Faculty of Science and Technology, Computing Science.
    Definition and validation of requirements management measures2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The quality of software systems depends on early activities in the software development process, of which the management of requirements is one. When requirements are not managed well, a project can fail or become more costly than intended, and the quality of the software developed can decrease. Among the requirements management practices, it is particularly important to quantify and predict requirements volatility, i.e., how much the requirements are likely to change over time. Software measures can help in quantifying and predicting requirements attributes like volatility. However, few measures have yet been defined, due to the fact that the early phases are hard to formalise. Furthermore, very few requirements measures have been validated, which would be needed in order to demonstrate that they are useful. The approach to requirements management in this thesis is quantitative, i.e. to monitor the requirements management activities and requirements volatility through software measurement. In this thesis, a set of 45 requirements management measures is presented. The measures were defined using the goal question metrics framework for the two predefined goals of the requirements management key process area of the capability maturity model for software. A subset of these measures was validated theoretically and empirically in four case studies. Furthermore, an analysis of validated measures in the literature was performed, showing that there is a lack of validated process, project, and requirements measures in software engineering. The studies presented in this thesis show that size measures are good estimators of requirements volatility. The important result is that size is relevant: increasing the size of a requirements document implies that the number of changes to requirements increases as well. Furthermore, subjective estimations of volatility were found to be inaccurate assessors of requirements volatility. These results suggest that practitioners should complement the subjective estimations for assessing volatility with the objective ones. Requirements engineers and project managers will benefit from the research presented in this thesis because the measures defined, proved to be predictors of volatility, can help in understanding how much requirements will change. By deploying the measures, the practitioners would be prepared for possible changes in the schedule and cost of a project, giving them the possibility of creating alternative plans, new cost estimates, and new software development schedules.

  • 22.
    Myllykoski, Mirko
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science. Department of Mathematical Information Technology, University of Jyväskylä.
    Rossi, Tuomo
    Department of Mathematical Information Technology, University of Jyväskylä.
    Toivanen, Jari
    Department of Mathematical Information Technology, University of Jyväskylä; Department of Aeronautics & Astronautics, Stanford University.
    On solving separable block tridiagonal linear systems using a GPU implementation of radix-4 PSCR method2018In: Journal of Parallel and Distributed Computing, ISSN 0743-7315, E-ISSN 1096-0848, Vol. 115, p. 56-66Article in journal (Refereed)
    Abstract [en]

    Partial solution variant of the cyclic reduction (PSCR) method is a direct solver that can be applied to certain types of separable block tridiagonal linear systems. Such linear systems arise, e.g., from the Poisson and the Helmholtz equations discretized with bilinear finite-elements. Furthermore, the separability of the linear system entails that the discretization domain has to be rectangular and the discretization mesh orthogonal. A generalized graphics processing unit (GPU) implementation of the PSCR method is presented. The numerical results indicate up to 24-fold speedups when compared to an equivalent CPU implementation that utilizes a single CPU core. Attained floating point performance is analyzed using roofline performance analysis model and the resulting models show that the attained floating point performance is mainly limited by the off-chip memory bandwidth and the effectiveness of a tridiagonal solver used to solve arising tridiagonal subproblems. The performance is accelerated using off-line autotuning techniques.

    The full text will be freely available from 2020-06-01 15:36
  • 23.
    Nilsson, Peter
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Reveman, David
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Glitz: hardware accelerated image compositing using OpenGL2004In: USENIX association proceedings of the FREENIX track, 2004 USENIX annual technical conference, Berkeley: USENIX - The Advanced Computing Systems Association, 2004, p. 29-40Conference paper (Refereed)
    Abstract [en]

    In recent years 2D graphics applications and window systems tend to use more demanding graphics features such as alpha blending, image transformations and anti-aliasing. These features contribute to the user interfaces by making it possible to add more visual effects as well as new usable functionalities. All together it makes the graphical interface a more hospitable, as well as efficient, environment for the user. Even with today's powerful computers these tasks constitute a heavy burden on the CPU. This is why many proprietary window systems have developed powerful 2D graphics engines to carry out these tasks by utilizing the acceleration capabilities in modem graphics hardware. We present Glitz, an open source implementation of such a graphics engine, a portable 2D graphics library that can be used to render hardware accelerated graphics. Glitz is layered on top of OpenGL and is designed to act as an additional backend for cairo, providing it with hardware accelerated output. Further-more, an effort has been made to investigate if the level of hardware acceleration provided by the X Window System can be improved by using Glitz to carry out its fundamental drawing operations.

  • 24. Pousttchi, Key
    et al.
    Tilson, David
    Lyytinen, Kalle
    Umeå University, Faculty of Social Sciences, Department of Informatics. Case Western Reserve Univ, Cleveland, OH 44106 USA; London Sch Econ, London, England.
    Hufenbach, Yvonne
    Introduction to the Special Issue on Mobile Commerce: Mobile Commerce Research Yesterday, Today, Tomorrow - What Remains to Be Done?2015In: International Journal of Electronic Commerce, ISSN 1086-4415, E-ISSN 1557-9301, Vol. 19, no 4, p. 1-20Article in journal (Other academic)
    Abstract [en]

    Mobile commerce (m-commerce) in the smartphone age is revolutionizing established value networks and transforming the wider economy. In this introduction we strive to build a bridge from the past of m-commerce research to its future. We examine more than a decade of research and conduct a Delphi study among leading scholars in the field. The review reveals significant changes in m-commerce topics as time goes on, and provides initial insights into what the future may hold for us. The most sobering finding is that the m-commerce field has still to establish a strong theoretical foundation. This has been reflected in less than overwhelming success in publishing on the subject in the most prestigious journals of the Information Systems discipline. At the same time, m-commerce forms one of the epicenters of the ongoing digitalization of our life. Therefore, we look forward to m-commerce research rising to the challenge and making significant contributions to understanding one of the important phenomena of our time.

  • 25.
    Sandqvist, Jonas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Collision detection using boundary representation, BREP2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis treats how to generate collision information for multibody simulations in AgX Dynamicswhere the geometries are described with the data structure boundary representation, BREP. BREP is adata structure that contains the exact mathematical description of each individual surface. To describecomplex surfaces exact and efficient non uniform rational basis spline, NURBS, is used and for trivialsurfaces like planes or spheres simpler equations is used. Since all surfaces in a BREP is described veryaccurate, the accuracy for the collision information can be set high without affecting the amount of dataneeded to describe the geometries.To make AgX Dynamics able to calculate forces in a multibody simulation, collision informationabout were and how much two geometries are intersecting is required. The collision information containswere the overlap between two geometries is, how much the objects have penetrated each other and thedirection for which the objects have to separate. To find the penetration depth and the overlap theNewton Raphson method were used. The experiments conducted, showed that it is possible to useBREPs as a description of geometries to produce the collision information needed for the physics engineused by AgX Dynamics to handle collisions. A comparison between trimesh and BREP for producingthe collision information, shows that data usage is much lower for the representation of geometries withBREPs than trimesh. The results also shows that the accuracy can be significantly higher than fortrimesh as the data usage for trimesh becomes non practical to handle when the required accuracy ishigh. With the high accuracy and with the smooth surfaces used with the BREP the artificial friction isalmost negligible except for cases were intersection points could not be found all around the intersectioncurves due to limitations in the algorithm.

  • 26.
    Sondell, Björn
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Nyberg, Lars
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Eriksson, Staffan
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Engström, Björn
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Backman, Anders
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Holmlund, Kenneth
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Bucht, Gösta
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Lundin-Olsson, Lillemor
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation.
    Altered walking pattern in a virtual environment2005In: Presence - Teleoperators and Virtual Environments, ISSN 1054-7460, E-ISSN 1531-3263, Vol. 14, no 2, p. 191-197Article in journal (Refereed)
    Abstract [en]

    Falls and fractures among elderly persons constitute a major health problem. Many falls occur while walking and falls that occur during turning often result in a fracture. Methods aimed at understanding the complex mechanisms involved in walking should therefore assess tested individuals during walks and turns. In order to identify persons at risk and take the correct preventive measures, it is important to find methods that quantify movements as the tested persons are processing multisensory input. In a clinical setting this is sometimes difficult to achieve in a controlled manner, since tests are difficult to set exactly the same from one time to another. Using a virtual environment (VE) and a tracker system, conditions such as light, sound, events, body movements, and room size can be controlled and measured. Tests in VE can therefore be identically reproduced over and over again to evaluate if a person can withstand changing outer demands at any given moment. In order to perform quantitative measures 8 persons (21-74 years) were tested in immersive virtual reality. The VE was a corridor in which expected and unexpected events could be produced. Events studied were doors swinging open in front of the subjects during a walk and a virtual tilting of the environment. Trackers were used for collecting and analyzing the movement data. Our results show that the system was well tolerated among the subjects and that there was a clear tendency that the system could generate fall tendency among the subjects. There was also a difference among the subjects regarding walking strategies when subjected to the various events.

  • 27.
    Sun, Jiong
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Li, Haibo
    Turn your mobile into the ball: rendering live football game by vibrationManuscript (preprint) (Other academic)
  • 28.
    Surie, Dipak
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Evaluation and Integration of Risk Management in CMMI and ISO/IEC 155042004Conference paper (Refereed)
    Abstract [en]

    During software development, software companies are exposed to risks (unwanted events) which lead to economic and competitive loss. Risk management technique can be used to minimise the loss in software projects. Some software process improvement models include risk management among their guidelines. The goal of this paper is to evaluate and analyse how risk management is handled by Capability Maturity Model Integration (CMMI) and International Organization for Standardization/International Electrotechnical Commision (ISO/IEC) 15504. A risk management framework is used in this evaluation study. The results of this study show that risk management in CMMI is more comprehensive than ISO/IEC 15504, but both models handle risk factors to appreciable extent.

  • 29.
    Söderlund, Henrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Autonomous email notification- and booking management system: In a property administration environment2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The contracting company is in the desire of an autonomous system that can do tedious administrative work that is today done manually. They would like to autonomically notify customers about incoming alarms from the customers’ real estates’ Data Under Centrals and to notify about bookings, in which a complete booking system has to be created, together with a file system analyzer that notifies about new files in the customers’ project folders. A notification system was made that was easily deployable and ready to use. The system had to be completely configurable for the contracting company to use it to its full potential. The notification system was to send notifications when a new alarm had entered the database, a booking had to be reminded of, a rebooking was made or a file had been added to the file system in a designated project folder. The contracting company had a web portal that was further developed in ASP.net in which a booking calendar and booking viewer page was added together with a form creation and management system. A demo buttons page was also added for generating demo notifications for the company to show it’s customers how the system responds to certain events. The employees at GATE IBS feel confident that this system will help them in their working environment to further strengthen their position as an industry leading business in control- and monitoring technology.

  • 30.
    Wiklund, Krister
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Andersson, Magnus
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Arrangement and method for performing movement analysis2013Patent (Other (popular science, discussion, etc.))
  • 31.
    Zhang, Hong
    et al.
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Jiangsu Univ, Dept Math, Zhenjiang 212013, Jiangsu, Peoples R China.
    Georgescu, Paul
    The global properties of an age-dependent SI model involving pathogenic virus release and defence mechanisms for pests2010In: Mathematical and computer modelling, ISSN 0895-7177, E-ISSN 1872-9479, Vol. 52, no 1-2, p. 37-54Article in journal (Refereed)
    Abstract [en]

    Insect pests are common but undesirable elements in ecosystems and represent thorny problems for most developing countries. To prevent pest outbreaks, growers often resort to insect-pathogenic viruses rather than to pesticides which affect human health and the environment. The purpose of this paper is to investigate a new age-structured pest management model which describes the interaction between susceptible insect pests, infected insect pests, pathogenic viruses and defence immunity mechanisms. A feature of this model is that it accounts for the dependence of the amount of pathogenic viruses released and of the efficiency of the defence mechanisms upon the so-called age of infection. First, the asymptotic behavior of the system is established via a monotonicity argument which makes use of several integral inequalities, being shown that the infection ultimately dies out, while under certain circumstances the susceptible pests also become extinct. By means of the Michailov criterion, one then analyzes the linearized stability of the trivial equilibrium and of the semi-trivial infected pest-free equilibrium. In this regard, it is observed that the defence mechanisms and maximal length of the infective period play important roles in the dynamics of the system. Several pest controls strategies are further investigated by means of numerical simulations, which show that when the dose of pathogenic viruses released initially is larger than a certain amount the profile of the response of defence mechanisms can be modified by changing this dose. Finally, the paper is concluded with a discussion on the biological significance of the mathematical results and framework.

  • 32.
    Östberg, Per-Olov
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Lockner, Niclas
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Reducing Complexity in Service Development and Integration2015In: Cloud computing and services sciences, CLOSER 2014, Springer Berlin/Heidelberg, 2015, p. 63-80Conference paper (Refereed)
    Abstract [en]

    The continuous growth and increasing complexity of distributed systems software has produced a need for software development tools and techniques that reduce the learning requirements and complexity of building distributed systems. In this work we address reduction of complexity in service-oriented software development and present an approach and a toolkit for multi-language service development based on three building blocks: a simplified service description language, an intuitive message serialization and transport protocol, and a set of code generation techniques that provide boilerplate environments for service implementations. The toolkit is intended for use in the eScience domain and is presented along with a performance evaluation that quantifies toolkit performance against that of selected alternative toolkits and technologies for service development. Toolkit performance is found to be comparable to or improve upon the performance of evaluated technologies.

1 - 32 of 32
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