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  • 1.
    Andersson, Rickard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Pseudo-optimal strategies in no-limit poker2006Ingår i: ICGA Journal, ISSN 1389-6911, Vol. 29, nr 3, s. 143-149Artikel i tidskrift (Refereegranskat)
    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 universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Lacoursière, Claude
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Servin, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Democratizing CAE with Interactive Multiphysics Simulation and Simulators2012Konferensbidrag (Övrigt vetenskapligt)
    Ladda ner fulltext (pdf)
    fulltext
  • 3.
    Bhuyan, Monowar H.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Xu, Lijie
    Institute of Software, CAS, China.
    Welcome message from the TPC chairs of IEEE JCC 20222022Ingår i: Proceedings: 2022 IEEE International Conference on Joint Cloud Computing (JCC), IEEE Computer Society, 2022, s. IX-IXKapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 4.
    Billing, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Servin, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Composer: A prototype multilingual model composition tool2013Ingår i: MODPROD2013: 7th MODPROD Workshop on Model-Based Product Development / [ed] Peter Fritzson, Umeå: Umeå universitet , 2013Konferensbidrag (Övrigt vetenskapligt)
    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

    Ladda ner (pdf)
    Slides
  • 5.
    Bonnaventure, William
    et al.
    SnT, University of Luxembourg, Luxembourg, Luxembourg.
    Khanfir, Ahmed
    SnT, University of Luxembourg, Luxembourg, Luxembourg.
    Bartel, Alexandre
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Papadakis, Mike
    SnT, University of Luxembourg, Luxembourg, Luxembourg.
    Traon, Yves Le
    SnT, University of Luxembourg, Luxembourg, Luxembourg.
    Confuzzion: a Java Virtual Machine Fuzzer for Type Confusion Vulnerabilities2021Ingår i: 2021 IEEE 21st International Conference on Software Quality, Reliability and Security (QRS), IEEE, 2021, s. 586-597Konferensbidrag (Refereegranskat)
    Abstract [en]

    Current Java Virtual Machine (JVM) fuzzersaim at generating syntactically valid Java programs, without targeting any particular use of the standard Java library. While effective, such fuzzers fail to discover specific kinds of bugs or vulnerabilities, such as type confusion, that are related to the standard API usage. To deal with this issue, we introduce amutation-based feedback-guided black-box JVM fuzzer, called CONFUZZION. CONFUZZION, as the name suggests, targets security-relevant object-oriented flaws with a particular focus on type confusion vulnerabilities. We show that in less than 4 hours, on commodity hardware and without any predefined initialization seed, CONFUZZION automatically generates Java programs that reveal JVM vulnerabilities, i.e., the Common Vulnerabilities and Exposures CVE-2017-3272. We also show that state-of-the-art fuzzers or even traditional automatic testing techniques are not capable of detecting such faults, even after 48 hours of execution in the same environment. To the best of our knowledge, CONFUZZION is the first fuzzer able to detect JVM type confusion vulnerabilities.

  • 6.
    Buckland, Philip I.
    et al.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Eriksson, Erik J.
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Palm, Fredrik
    Umeå universitet, Humanistiska fakulteten, Humlab.
    SEAD - The Strategic Environmental Archaeology Database: Progress Report Spring 20142014Rapport (Övrigt vetenskapligt)
    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.

    Ladda ner fulltext (pdf)
    SEAD - Progress Report Spring 2014
  • 7.
    Börstler, Jurgen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Christensen, Henrik B
    Nordström, Marie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kallin Westin, Lena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Moström, Jan Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Caspersen, Michael E
    Evaluating OO Example Programs for CS12008Ingår i: Proceedings of the 13th annual conference on Innovation and technology in computer science education, 2008, s. 47-52Konferensbidrag (Refereegranskat)
  • 8.
    Börstler, Jürgen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten.
    Using Role-Play Diagrams to Improve Scenario Role-Play2010Ingår i: 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, s. 309-334Kapitel i bok, del av antologi (Refereegranskat)
    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.

  • 9.
    Börstler, Jürgen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nordström, Marie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kallin Westin, Lena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Moström, Jan Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Christensen, Henrik B.
    Bennedsen, Jens
    An Evaluation Instrument for Object-Oriented Example Programs for Novices2008Rapport (Övrigt vetenskapligt)
  • 10.
    Chaudhry, Tanmay
    et al.
    SimScale GmbH, Germany.
    Doblander, Christoph
    Technische Universität München, Germany.
    Dammer, Anatol
    SimScale GmbH, Germany.
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Jacobsen, Hans-Arno
    Technische Universität München, Germany.
    Retrofitting Admission Control in an Internet-Scale Application2016Rapport (Övrigt vetenskapligt)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 11. Chaudhry, Tanmay
    et al.
    Doblander, Christoph
    Dammer, Anatol
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Jacobsen, Hans-Arno
    Retrofitting Admission Control in an Internet-Scale Application2016Rapport (Övrigt vetenskapligt)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 12.
    Eriksson, Magnus
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Datavetenskap.
    An approach to software product line use case modeling2006Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 13. 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 Systems2017Ingår i: ACM Transactions on Autonomous and Adaptive Systems, ISSN 1556-4665, E-ISSN 1556-4703, Vol. 11, nr 4, artikel-id 24Artikel i tidskrift (Refereegranskat)
    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.

  • 14. Führer, Claus
    et al.
    Solem, Jan-Erik
    Verdier, Olivier
    Computing with Python: An introduction to Python for science and engineering2014Bok (Refereegranskat)
  • 15. Führer, Claus
    et al.
    Solem, Jan-Erik
    Verdier, Olivier
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Computing with Python: An introduction to Python for science and engineering2013Bok (Refereegranskat)
  • 16.
    Granat, Robert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Kågström, Bo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Kressner, Daniel
    ETH, Zürich.
    Parallel Eigenvalue Reordering in Real Schur Forms2009Ingår i: Concurrency and Computation, ISSN 1532-0626, E-ISSN 1532-0634, Vol. 21, nr 9, s. 1225-1250Artikel i tidskrift (Refereegranskat)
    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.

  • 17.
    Granberg, Tony
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Mjukvara för träning av routersyntax2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det här arbetet handlar om en mjukvara vars mål är att tillhandahålla syntaxträning inom routeradministration inriktad mot målgruppen studenter. Mjukvaran har programmerats från grunden i programmeringsspråket Python och är menad att erbjuda ett simplistiskt användargränsnitt. Programmeringen har resulterat i ett program som döpts till Routersyntax och består av två delar: ett klientprogram och ett serverprogram. Både klientprogrammet och serverprogrammet går att installera och köra i flera olika operativsystemmiljöer, med främsta fokus på Windows, Ubuntu Linux och OS X. Det är simplistiskt utformat, enkelt att installera och köra, samt gratis att använda för studenter.

    Förhoppningen är att användaren med hjälp av syntaxträningsmjukvaran ska få en chans att träna sina färdigheter i att skriva routerkommandon för användning av studenter i universitetskurser.


    Ladda ner fulltext (pdf)
    Mjukvara för träning av routersyntax
  • 18.
    Hegner, Stephen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Internal representation of database views2010Ingår i: Journal of universal computer science (Online), ISSN 0948-695X, E-ISSN 0948-6968, Vol. 16, nr 20, s. 2956-2985Artikel i tidskrift (Refereegranskat)
    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.

  • 19.
    Hällgren, Markus
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Handelshögskolan vid Umeå universitet (USBE).
    Söderholm, Anders
    Mittuniversitetet.
    Projects-as-practice: new approach, new insights2011Ingår i: The Oxford handbook of project management / [ed] Peter W.G. Morris; Jeffrey K. Pinto; Jonas Söderlund, Oxford University Press, 2011, s. 500-518Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    This article mainly focuses on projects-as-practice based in the social sciences, and it suggests that the situated practice side of a social phenomenon is also important as a basis of study for understanding what is done. While the study is empirical, it focuses on the actions and actors involved in building or organizing environments, rather than simply looking at aggregated social processes or structures. With this approach, projects are seen as the sum of the actions of the people involved, which emphasizes both how people involved in projects act and how their typical workdays are structured. This may shed light on areas such as the importance of project management practice for strategic organizational change or the improvisation that is necessary for project execution.

  • 20.
    Javed, Asad
    et al.
    Aalto University.
    Robert, Jérémy
    University of Luxembourg.
    Heljanko, Keijo
    University of Helsinki.
    Främling, Kary
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    IoTEF: A Federated Edge-Cloud Architecture for Fault-Tolerant IoT Applications2020Ingår i: Journal of Grid Computing, ISSN 1570-7873, E-ISSN 1572-9184, Vol. 18, s. 57-80Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The evolution of Internet of Things (IoT) technology has led to an increased emphasis on edge computing for Cyber-Physical Systems (CPS), in which applications rely on processing data closer to the data sources, and sharing the results across heterogeneous clusters. This has simplified the data exchanges between IoT/CPS systems, the cloud, and the edge for managing low latency, minimal band- width, and fault-tolerant applications. Nonetheless, many of these applications administer data collec- tion on the edge and offer data analytic and storage 

    capabilities in the cloud. This raises the problem of separate software stacks between the edge and the cloud with no unified fault-tolerant management, hin- dering dynamic relocation of data processing. In such systems, the data must also be preserved from being corrupted or duplicated in the case of intermittent long-distance network connectivity issues, malicious harming of edge devices, or other hostile environ- ments. Within this context, the contributions of this paper are threefold: (i) to propose a new Internet of Things Edge-Cloud Federation (IoTEF) architec- ture for multi-cluster IoT applications by adapting our earlier Cloud and Edge Fault-Tolerant IoT (CEFIoT) layered design. We address the fault tolerance issue by employing the Apache Kafka publish/subscribe platform as the unified data replication solution. We also deploy Kubernetes for fault-tolerant manage- ment, combined with the federated scheme, offering a single management interface and allowing automatic reconfiguration of the data processing pipeline, (ii) to formulate functional and non-functional requirements of our proposed solution by comparing several IoT architectures, and (iii) to implement a smart build- ings use case of the ongoing Otaniemi3D project as proof-of-concept for assessing IoTEF capabilities. The experimental results conclude that the architec- ture minimizes latency, saves network bandwidth, and handles both hardware and network connectivity based failures.

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    fulltext
  • 21. Javed, Asad
    et al.
    Yousefnezhad, Narges
    Robert, Jérémy
    Heljanko, Keijo
    Främling, Kary
    Department of Computer Science, Aalto University, Espoo, Finland.
    Access Time Improvement Framework for Standardized IoT Gateways2019Ingår i: 2019 IEEE International Conference on Pervasive Computing and Communications Workshops (PerCom Workshops), IEEE, 2019, s. 220-226Konferensbidrag (Refereegranskat)
    Abstract [en]

    Internet of Things (IoT) is a computing infrastructure underlying powerful systems and applications, enabling autonomous interconnection of people, vehicles, devices, and information systems. Many IoT sectors such as smart grid or smart mobility will benefit from the recent evolutions of the smart city initiatives for building more advanced IoT services, from the collection of human- and machine-generated data to their storage and analysis. It is therefore of utmost importance to manage the volume, velocity, and variety of the data, in particular at the IoT gateways level, where data are published and consumed. This paper proposes an access time improvement framework to optimize the publication and consumption steps, the storage and retrieval of data at the gateways level to be more precise. This new distributed framework relies on a consistent hashing mechanism and modular characteristics of microservices to ensure a flexible and scalable solution. Applied and assessed on a real case study, experimental results show how the proposed framework improves data access time for standardized IoT gateways.

  • 22.
    Johansson Hultberg, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet.
    Parallellisering av Sliding Extensive Cancellation Algorithm (ECA-S) för passiv radar med OpenMP2021Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Parallellisering av mjukvara har fått ett ökat intresse sedan transistortillverkningen av mindre chip inom en integrerade krets har börjat att stagnera. Detta har lett till utveckling av moderna processorer med ett ökande antal av kärnor. Parallellisering är en optimeringsteknik vilken tillåter användaren att utnyttja parallella processer till att effektivisera algoritmflöden. Denna studie undersöker de tidsmässiga fördelar ett passivt bistatiskt radarsystem kan erhålla genom att, bland annat tillämpa parallellisering och omformning. Studien fokuserar främst på att undersöka användandet av parallella trådar inom det delade minnesutrymmet på en centralprocessor (CPU), detta med hjälp av applikationsprogrammeringsgränssnittet OpenMP. Kvantitativa jämförelser tas fram med hjälp av en av de mest centrala algoritmerna inom det passiva radarsystemet, nämligen Extensive Cancellation Algorithm (ECA). ECA kan används till att undertrycka oönskat klotter i övervakningssignalen, vilket har till syfte att skapa klara måldetektioner av luftföremål. Algoritmen är däremot beräkningstung, vilket har medfört utveckling av snabbare versioner som exempelvis Sliding ECA (ECA-S). Trots utvecklingen är algoritmen fortfarande relativt beräkningstung och kan medföra en lång exekeveringstid inom hela radarsystemet. I denna studie transformeras en MATLAB-implementation av ECA-S till C för att kunna dra nytta av den snabba exekeveringstiden i det procedurella programmeringsspråket. Parallellism införs inom den transformerade algoritmen med hjälp av Intels trådmetodik och appliceras sedan inom två olika operativsystem. Studien visar på en tidsmässig optimering i C med upp till 24 gånger snabbare exekeveringstid och bibehållen noggrannhet. Resultaten visade även på att en enklare omformning av en MATLAB-algoritm kunde resultera till 73% snabbare kod och att en C-MEX-implementation är dubbelt så långsam i jämförelse med en C-implementering. Slutligen pekade studien på att realtid kan uppnås för ett passivt bistatiskt radarsystem vid användandet av programmeringsspråket C och med utnyttjandet av parallella instruktioner inom det delade minnet på en CPU.

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    Andreas J. Hultberg examensarbete
  • 23.
    Johansson, Pedher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Matrix canonical structure toolbox2006Rapport (Övrig (populärvetenskap, debatt, mm))
  • 24.
    Johansson, Pedher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    StratiGraph developer's guide2006Rapport (Övrigt vetenskapligt)
  • 25.
    Johansson, Pedher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    StratiGraph software design and algorithms2006Rapport (Övrig (populärvetenskap, debatt, mm))
  • 26.
    Johansson, Pedher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    StratiGraph user's guide2003Rapport (Övrigt vetenskapligt)
  • 27.
    Loconsole, Annabella
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Datavetenskap.
    Definition and validation of requirements management measures2007Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    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.

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    FULLTEXT01
  • 28.
    Lundqvist, Gustav
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Temp-validering av PCR-utrustning: MATLAB-applikation och användbarhetstest2023Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Polymeras Chain Reaction (PCR) är i dagens samhälle ett oumbärligt verktyg förlaboratorie- och analysverksamhet. Avdelningarna Genetik och Mikrobiologi på Norrlands universitetssjukhus har sammanlagt ca 25 PCR-utrustningar som alla är i behov av regelbundna kontroller. Kontrollerna görs av sjukhusets egna ingenjörer med en egentillverkad mätutrustning för temperaturmätning i utrustningen. Den tillhörande programvaran är över tio år gammal samt bunden till en dator och är i behov av att förnyas för att framtidssäkra möjligheten till kontroller inom byggnaden. Arbetet har gått ut på att utveckla en applikation i MATLAB r2018b som med temperaturmätning validerar PCR-maskiners funktion och prestanda. Den resulterande applikationen består i ett grafiskt användargränssnitt, datainsamling, dataanalys och rapportgenerering. Applikationen utvärderades genom ett användbarhetstest med en testgrupp bestående av två ingenjörer. Efter användartestet vidtogs åtgärder för att tillfredsställa testpersonernas önskemål angående funktion och utseende. Den slutgiltiga applikationen är ett kompilerat MATLAB-program som visar datainsamling i realtid, har automatisk stopp och start, genererar rapport och intyg samt har funktion för kalibrering av mätprober. Arbetet resulterade även i en lista över funktioner och metoder som inte är tillgänglig i aktuell version av MATLAB. För att uppgradera till en nyare version av MATLAB krävs en nyare hårdvara med tillhörande drivrutiner. Listan är motiveringen till varför en nyare hårdvara borde införskaffas vid vidareutveckling i framtiden. En nyare hårdvara borde vara kompatibel med nyaste versionen av MATLAB (r2023a), kunna sampla minst 12 kanaler samt ha en samplingsfrekvens på minst 4 Hz.

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    Temp-validering av PCR-utrustning
  • 29.
    Lyxell, Oskar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Server-Side Rendering in React: When Does It Become Beneficial to Your Web Program?2023Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In recent years the technology of web application development has improved a lot and JavaScript frameworks such as React and Angular have increased in popularity. These frameworks use client-side rendering and have led to the rendering method’s increase in popularity compared to its previous conqueror; server-side rendering. Server-side rendering, however, is still a viable option in certain cases. For instance, it provides improved performance on computers depending on the hardware specification and search engine optimization. This thesis is an experimental study that aims to present knowledge regarding the rendering method's benefits and drawbacks. The study also presents when server-side rendering becomes beneficial to your web program compared to client-side rendering. The thesis also includes another rendering method using client-side rendering but with a configuration called virtualized. In this study, two identical web applications containing a grid were built. The rendering method using the server side was on one application and rendering methods using the client side were on the other application. The evaluation metrics of the rendering methods were the time to render the grid and how good of a user experience they provided. The results show that virtualized offers a faster rendering time and better user experience, especially at larger grids. Server-side rendering was faster than client-side rendering at all grid sizes and they had a similar user experience. Overall, this thesis suggests using virtualized when suited. Regarding server-side rendering, this thesis recommends using it carefully since it requires complex implementation and maintenance along with higher costs. Therefore, it comes down to the requirements of the application and if it is worth the complex implementation, cost, and maintenance.   

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    Server-Side Rendering in React: When Does It Become Beneficial to Your Web Program?
  • 30.
    Metsch, Thijs
    et al.
    Intel Labs, Intel Cooperation, Hillsboro, United States.
    Viktorsson, Magdalena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hoban, Adrian
    Network and Edge Group, Intel Cooperation, Hillsboro, United States.
    Vitali, Monica
    Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Milan, Italy.
    Iyer, Ravi
    Intel Labs, Intel Cooperation, Hillsboro, United States.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Intent-driven orchestration: enforcing service level objectives for cloud native deployments2023Ingår i: SN Computer Science, ISSN 2662-995X, Vol. 4, nr 3, artikel-id 268Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The introduction of microservices and functions using serverless deployment styles for cloud-native applications will trigger a shift in the orchestration paradigm towards an intent-driven model. In this model we shift from imperatively declaring an object’s state to the declaration of a set of desired intents. Intent-driven orchestration (IDO) enables the management of applications through their service level objectives (SLOs) while minimizing service owner and administrator overhead. By enabling service owners to express the desired target key performance indicator (KPI) objectives for their service components instead of declaratively defining the required state and resources, we enable ease of use and abstraction from underlying platforms. By adding a planning component to a Kubernetes-based orchestration stack, the feasibility of translating service objectives into actionable decisions is demonstrated. As this new architecture component introduces more autonomy in the control plane, a means to evaluate the results of planning is defined.

  • 31.
    Monga, Hitesh Chander
    et al.
    Aalto University.
    Kinnunen, Tuomas
    Aalto University.
    Malhi, Avleen
    Aalto University.
    Javed, Asad
    Aalto University.
    Främling, Kary
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Department of Computer Science, Aalto University, Finland.
    An OAuth-based Authentication Mechanism for Open Messaging Interface Standard2020Ingår i: Proceedings of the 12th International Conference on Agents and Artificial Intelligence / [ed] Ana Rocha, Luc Steels and Jaap van den Herik, SciTePress, 2020, Vol. 1, s. 216-225Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Internet of Things (IoT) security and privacy remain a major challenge, especially due to the highly scalable and distributed nature of IoT networks. IoT security has an exceptionally wide scope which also leads to the most demanding requirements needed for the widespread realization of many IoT visions. It includes the tasks such as trusted sensing, computation, communication, privacy in terms of security scope. A large number of industry-driven domain specific standards has been developed which hinder the development of a single IoT ecosystem. O-MI and O-DF standards were previously proposed to address the challenge of interoperability in IoT devices. This paper highlights and discusses the measures taken to enhance the security of these standards by integration of OAuth 2.0 service provider functionality with the O-MI authentication module along with the existing security module. The security architecture has been proposed which enhances the security features by providing autho rization without use of certificates. The implementation details of the plug-in module for envisioned security model developed for the O-MI and O-DF standards have been discussed.

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    fulltext
  • 32.
    Myllykoski, Mirko
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. 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 method2018Ingår i: Journal of Parallel and Distributed Computing, ISSN 0743-7315, E-ISSN 1096-0848, Vol. 115, s. 56-66Artikel i tidskrift (Refereegranskat)
    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.

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    fulltext
  • 33.
    Myrberg, Frans
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    INTEGRERING AV API-DRIVNA STRATEGIER FÖR ENERGIEFFEKTIV UPPVÄRMNINGSOPTIMERING I BOSTADSBYGGNADER2023Självständigt arbete på avancerad nivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta projekts syfte är utformat för att se om det går att skapa ett program som i realtid hämtardata över spotpriser för både el och fjärrvärme och sedan utifrån detta tas medvetna beslut omvilket uppvärmningssystem som är billigast i nuläget. Allt detta för att uppvärmningskostnadenska bli lägre för fastighetsägaren.Den färdiga implementationen fungerar som förväntat men med haken att den ej har testas pånågon skarp anläggning så viss hänsyn bör tas. Resultatet programmet tar levereras sedan somen logiska 1 (fjärrvärme) eller 0 (el) ut ur programmet för att andra system i Niagara frameworketska kunna ha användning av det.   

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    fulltext
  • 34.
    Nilsson, Peter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Reveman, David
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Glitz: hardware accelerated image compositing using OpenGL2004Ingår i: USENIX association proceedings of the FREENIX track, 2004 USENIX annual technical conference, Berkeley: USENIX - The Advanced Computing Systems Association, 2004, s. 29-40Konferensbidrag (Refereegranskat)
    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.

  • 35.
    Nyquist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Investigating the Effectiveness of Forward-Porting Bugs2023Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This research investigates the effectiveness of the forward-porting approach employed in the Magma framework as a fault injection technique for evaluating fuzzers. The study aims to assess the use of Proof-of-Concepts in reproducing crashes in CVEs and evaluate the feasibility of forward-porting vulnerabilities into later software versions. An experiment was conducted using three selected open-source libraries to explore whether vulnerabilities could be triggered or reached in the latest versions through the forward-porting approach. The findings suggest that the forward-porting approach may not be the most effective method for injecting vulnerabilities into software systems. Out of the 22 chosen CVEs for analysis, only one could be triggered and two could be reached using the forward-porting approach. This indicates that many of the injected vulnerabilities become obsolete or have unsatisfiable trigger conditions in later versions. Additionally, manual verification of these vulnerabilities have been found to be time-consuming and challenging. Further research is necessary to provide a comprehensive evaluation of the effectiveness of the forward-porting approach in vulnerability injection.

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    Investigating the Effectiveness of Forward-Porting Bugs
  • 36.
    Papadopoulos, Alessandro V.
    et al.
    Mälardalen University, Sweden.
    Versluis, Laurens
    Vrije Universiteit Amsterdam, Netherlands.
    Bauer, André
    University of Würzburg, Germany.
    Herbst, Nikolas
    University of Würzburg, Germany.
    von Kistowski, Jóakim
    University of Würzburg, Germany.
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Abad, Cristina L.
    Escuela Superior Politecnica del Litoral, Ecuador.
    Amaral, José Nelson
    University of Alberta, Canada.
    Tůma, Petr
    Charles University, Czech Republic.
    Iosup, Alexandru
    Vrije Universiteit Amsterdam, Netherlands.
    Methodological Principles for Reproducible Performance Evaluation in Cloud Computing2020Ingår i: Lecture Notes in Informatics (LNI), Proceedings - Series of the Gesellschaft fur Informatik (GI), Gesellschaft fur Informatik (GI) , 2020, Vol. P300, s. 93-94Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work, we report on our recent article on "Methodological Principles for Reproducible Performance Evaluation in Cloud Computing" published in the IEEE Transactions on Software Engineering (TSE)[Pa19]. This publication is a result of a joint effort coordinated by the Cloud Research Working Group of SPEC (Standard Performance Evaluation Corporation).

  • 37. Pousttchi, Key
    et al.
    Tilson, David
    Lyytinen, Kalle
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för informatik. 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?2015Ingår i: International Journal of Electronic Commerce, ISSN 1086-4415, E-ISSN 1557-9301, Vol. 19, nr 4, s. 1-20Artikel i tidskrift (Övrigt vetenskapligt)
    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.

  • 38.
    Saleh Sedghpour, Mohammad Reza
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Towards self-driving microservices2023Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Mikrotjänster har de senaste åren blivit en populär arkitekturmodell för programvara. Modellen innebär att man skapar applikationer med flera små tjänster, var och en med flera instanser som fungerar som oberoende processer. Mikrotjänsters distribuerade natur gör kommunikationen mellan tjänster mer utmanande. Denna komplexitet kan även ge upphov till tillfälliga fel på grund av lastobalans eller överbelastning och även försämra applikationers prestanda. Av denna anledning är dynamisk konfigurationav kommunikationen mellan mikrotjänster nödvändig. En service mesh är en teknikplattform för att hantera hur mikrotjänster kommunicerar, med funktioner för att enkelt kryptera kommunikation mellan tjänster, mäta prestanda och finkorningt styra kommunikationsflöden.En service mesh implementeras ofta som en uppsättning konfigurerbara proxies. Detta möjliggör trafikhanteringspolicies baserade på mekanismer som kretsbrytning och omsändningar. Statisk konfiguration av dessa mekanismer kan dock ge allvarliga prestandaproblem såsom  låg genomströmning och/eller omfattande omsändningar.

    Denna avhandling har tre mål. För det första undersöker den hur trafikhantering för mikrotjänster påverkar tillförlitligheten och tillgängligheten för applikationer vid tillfälliga störningar. För det andra fokuserar den på adaptiv reglering av trafikhantering av mikrotjänster för att öka genomströmningen och samtidigt bibehålla acceptabla svarstider. För det tredje syftar den till att förbättra reproducerbarheten i forskning inom distribuerade system och se till att forskningsresultat enklare kan verifieras av oberoende. 

    För att uppnå dessa mål undersöker avhandlingen den tekniska frontlinjen inom service mesh och mikrotjänster driva av eBPF-tekniken. Avhandlingen analyserar vidare hur användandet av kretsbrytare och omsändningsmekanismer påverkar mikrotjänsters prestanda. Adaptiva reglersystem för att hantera konfiguration av båda dessa mekanismer föreslås och utvärderas i omfattande experimentent. Resultaten visar att sådana regulatorer är nödvändiga för att öka genomströmningen och samtidigt bibehålla (högre percentiler av) applikationers svarstider. Adaption är särskilt viktigt då faktorer som totala trafikmängden, applikationers prestanda, tillfälliga fel, etc. kan förändras snabbt. 

    Avhandlingen introducerar även ett verktyg för att generera godtyckliga testapplikationer för att kunna genomföra mer heltäckande utvärderingar av olika typer av forskningsprogramvara som hanterar mikrotjänster. Avhandlingen bidrar även till reproducerbarhet genom att studera hur programvaru-artefakter bäst bör utvärderas inom forskningsområdet distribuerade system. Detta sker genom att sammanställa, och utöka, befintliga rekommendationer inom området.

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    fulltext
    Ladda ner (pdf)
    spikblad
  • 39.
    Saleh Sedghpour, Mohammad Reza
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Garlan, David
    Carnegie Mellon University, Pittsburgh, USA.
    Schmerl, Bradley
    Carnegie Mellon University, Pittsburgh, USA.
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Breaking the vicious circle: self-adaptive microservice circuit breaking and retry2023Ingår i: 2023 IEEE international conference on cloud engineering: proceedings / [ed] Lisa O’Conner, IEEE Computer Society, 2023, s. 32-42, artikel-id 24126172Konferensbidrag (Refereegranskat)
    Abstract [en]

    Microservice-based architectures consist of numerous, loosely coupled services with multiple instances. Service meshes aim to simplify traffic management and prevent microservice overload through circuit breaking and request retry mechanisms. Previous studies have demonstrated that the static configuration of these mechanisms is unfit for the dynamic environment of microservices. We conduct a sensitivity analysis to understand the impact of retrying across a wide range of scenarios. Based on the findings, we propose a retry controller that can also work with dynamically configured circuit breakers. We have empirically assessed our proposed controller in various scenarios, including transient overload and noisy neighbors while enforcing adaptive circuit breaking. The results show that our proposed controller does not deviate from a well-tuned configuration while maintaining carried response time and adapting to the changes. In comparison to the default static retry configuration that is mostly used in practice, our approach improves the carried throughput up to 12x and 32x respectively in the cases of transient overload and noisy neighbors.

  • 40.
    Sandqvist, Jonas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Collision detection using boundary representation, BREP2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta examensarbete behandlar hur man skapar kollisionsinformation för flerkropps simuleringar i AgXDynamics där geometrier beskrivs med datastrukturen boundary representation, BREP. BREP är endatastruktur som innehåller den exakta matematiska beskrivningen för varje enskild yta. Att beskrivakomplexa ytor exakta och effektivt med non uniform rationell basis spline, NURBS, används och förtriviala ytor som plan eller sfärer kan enklare ekvationer används. Eftersom alla ytor i en BREP beskrivsexakt, kan noggrannheten för kollisions informationen sättas högt utan att påverka den mängd data sombehövs för att beskriva geometrier.För att göra AgX Dynamics kunna beräkna krafter i en flerkroppssimulering, krävs kollisions informationom var och hur mycket två geometrier kolliderar. Kollisions informationen innehåller varöverlappningen mellan två geometrier är, hur mycket objekten har penetrerat varandra och den riktningsom föremålen ska separeras. För att hitta penetrationsdjup och överlapp användes Newton Raphsonsmetod. De experiment som utförts, visade att det är möjligt att använda BREPs som en beskrivning avgeometrier för att producera kollisions information som behövs för att den fysikmotor som används avAGX Dynamics ska kunna hantera kollisioner. En jämförelse mellan trimesh och BREP för att producerakollisionen informationen, visar att dataanvändning är mycket lägre när geometrier representeras medBREPs än trimesh. Resultaten visar också att noggrannheten kan vara väsentligt högre för BREP änför trimesh eftersom dataanvändning för trimesh blir opraktiskt att hantera när noggrannheten är hög.Med hög noggrannhet och med de släta ytor som används med BREP blev den artificiella friction nästanförsumbar, utom i fallen där skärningspunkter inte kunde hittas runt hela skärningskurvor på grund avbegränsningar i algoritmen.

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    Collision detection using boundary representation, BREP
  • 41.
    Sayar, Imen
    et al.
    University of Toulouse, Blagnac Cedex, France.
    Bartel, Alexandre
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Bodden, Eric
    Paderborn University, Paderborn, Germany.
    Le Traon, Yves
    University of Luxembourg, Kirchberg Campus, Luxembourg.
    An in-depth study of Java deserialization remote-code execution exploits and vulnerabilities2023Ingår i: ACM Transactions on Software Engineering and Methodology, ISSN 1049-331X, E-ISSN 1557-7392, Vol. 32, nr 1, artikel-id 25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nowadays, an increasing number of applications use deserialization. This technique, based on rebuilding the instance of objects from serialized byte streams, can be dangerous since it can open the application to attacks such as remote code execution (RCE) if the data to deserialize is originating from an untrusted source. Deserialization vulnerabilities are so critical that they are in OWASP's list of top 10 security risks for web applications. This is mainly caused by faults in the development process of applications and by flaws in their dependencies, i.e., flaws in the libraries used by these applications. No previous work has studied deserialization attacks in-depth: How are they performed? How are weaknesses introduced and patched? And for how long are vulnerabilities present in the codebase? To yield a deeper understanding of this important kind of vulnerability, we perform two main analyses: one on attack gadgets, i.e., exploitable pieces of code, present in Java libraries, and one on vulnerabilities present in Java applications. For the first analysis, we conduct an exploratory large-scale study by running 256515 experiments in which we vary the versions of libraries for each of the 19 publicly available exploits. Such attacks rely on a combination of gadgets present in one or multiple Java libraries. A gadget is a method which is using objects or fields that can be attacker-controlled. Our goal is to precisely identify library versions containing gadgets and to understand how gadgets have been introduced and how they have been patched. We observe that the modification of one innocent-looking detail in a class - such as making it public - can already introduce a gadget. Furthermore, we noticed that among the studied libraries, 37.5% are not patched, leaving gadgets available for future attacks.For the second analysis, we manually analyze 104 deserialization vulnerabilities CVEs to understand how vulnerabilities are introduced and patched in real-life Java applications. Results indicate that the vulnerabilities are not always completely patched or that a workaround solution is proposed. With a workaround solution, applications are still vulnerable since the code itself is unchanged.

  • 42.
    Sjödin, Rickard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Interpolation and visualization of sparse GPR data2020Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Ground Penetrating Radar is a tool for mapping the subsurface in a noninvasive way. The radar instrument transmits electromagnetic waves and records the resulting scattered field. Unfortunately, the data from a survey can be hard to interpret, and this holds extra true for non-experts in the field. The data are also usually in 2.5D, or pseudo 3D, meaning that the vast majority of the scanned volume is missing data. Interpolation algorithms can, however, approximate the missing data, and the result can be visualized in an application and in this way ease the interpretation.

    This report has focused on comparing different interpolation algorithms, with extra focus on behaviour when the data get sparse. The compared methods were: Linear, inverse distance weighting, ordinary kriging, thin plate splines and fk domain zone-pass POCS. They were all found to have some strengths and weaknesses in different aspects, although ordinary kriging was found to be the most accurate and created the least artefacts. Inverse distance weighting performed surprisingly well considering its simplicity and low computational cost. A web-based, easy-to-use visualization application was developed in order to view the results from the interpolations. Some of the tools implemented include time slice, crop of a 3D cube, and iso surface.

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    fulltext
  • 43.
    Sondell, Björn
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Eriksson, Staffan
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Engström, Björn
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Backman, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Holmlund, Kenneth
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Bucht, Gösta
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Lundin-Olsson, Lillemor
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering.
    Altered walking pattern in a virtual environment2005Ingår i: Presence - Teleoperators and Virtual Environments, ISSN 1054-7460, E-ISSN 1531-3263, Vol. 14, nr 2, s. 191-197Artikel i tidskrift (Refereegranskat)
    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.

  • 44.
    Sun, Jiong
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    Turn your mobile into the ball: rendering live football game by vibrationManuskript (preprint) (Övrigt vetenskapligt)
  • 45.
    Surie, Dipak
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Evaluation and Integration of Risk Management in CMMI and ISO/IEC 155042004Konferensbidrag (Refereegranskat)
    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.

  • 46.
    Söderlund, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Autonomous email notification- and booking management system: In a property administration environment2017Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det uppdragsgivande företaget önskar ett autonomt system som kan utföra tidskrävande administrativt arbete som idag utförs manuellt. De vill autonomt informera kunderna om inkommande larm från kundens fastigheters "Data Under Centrals" samt meddela om bokningar där ett komplett bokningssystem måste skapas tillsammans med en filsystemanalysator som meddelar om nya filer i kundens projektmapp. Ett notifikationssystem gjordes som var enkelt att distribuera och redo att använda. Systemet måste vara helt konfigurerbart för att det uppdragsgivande bolaget ska kunna använda programmet till sin fulla potential. Anmälningssystemet skulle skicka meddelanden när ett nytt larm hade kommit in i databasen, en bokning måste påminnas om, ombokning gjordes eller en fil hade lagts till filsystemet i en utsedd projektmapp. Kontraktsföretaget hade en webbportal som vidareutvecklades i ASP.net där en bokningskalender och bokningsvisningssida lagts till tillsammans med ett formulärgenererings- och formulärhanteringssystem och en demoknappssida för att generera demonotifikationer för att företaget ska kunna visa kunderna hur systemet svarar på vissa händelser. De anställda på GATE IBS är övertygade om att detta system kommer att hjälpa dem i sin arbetsmiljö för att ytterligare stärka sin ställning som branschledande företag inom kontroll- och övervakningsteknik.

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  • 47.
    Viktorsson, William
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Klein, Cristian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Elastisys AB.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Elastisys AB.
    Security-Performance Trade-offs of Kubernetes Container Runtimes2020Ingår i: 2020 28th International Symposium on Modeling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS), IEEE, 2020, s. 1-4Konferensbidrag (Refereegranskat)
    Abstract [en]

    The extreme adoption rate of container technologies along with raised security concerns have resulted in the development of multiplealternative container runtimes targeting security through additional layers of indirection. In an apples-to-apples comparison, we deploy three runtimesin the same Kubernetes cluster, the security focused Kata and gVisor, as well as the default Kubernetes runtime runC. Our evaluation based on three real applications demonstrate that runC outperforms the more secure alternatives up to 5x, that gVisor deploys containers up to 2x faster than Kata, but that Kata executes container up to 1.6x faster than gVisor. Our work illustrates that alternative, more secure, runtimes can be used in a plug-and-play manner in Kubernetes, but at a significant performance penalty. Our study is useful both to practitioners - to understand the current state of the technology in order to make the right decision in the selection, operation and/or design of platforms - and to scholars to illustrate how these technologies evolved over time.

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    fulltext
  • 48.
    Wiklund, Krister
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Arrangement and method for performing movement analysis2013Patent (Övrig (populärvetenskap, debatt, mm))
  • 49.
    Zhang, Chongsheng
    et al.
    Henan Key Lab of Big Data Analysis and Processing, Henan University, Henan, China.
    Soda, Paolo
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Department of Engineering, University Campus Bio-Medico of Rome, Rome, Italy.
    Bi, Jingjun
    Henan Key Lab of Big Data Analysis and Processing, Henan University, Henan, China.
    Fan, Gaojuan
    Henan Key Lab of Big Data Analysis and Processing, Henan University, Henan, China.
    Almpanidis, George
    Henan Key Lab of Big Data Analysis and Processing, Henan University, Henan, China.
    García, Salvador
    DaSCI Andalusian Research Institute, University of Granada, Granada, Spain.
    Ding, Weiping
    School of Information Science and Technology, Nantong University, Nantong, China.
    An empirical study on the joint impact of feature selection and data resampling on imbalance classification2023Ingår i: Applied intelligence (Boston), ISSN 0924-669X, E-ISSN 1573-7497, Vol. 53, s. 5449-5461Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many real-world datasets exhibit imbalanced distributions, in which the majority classes have sufficient samples, whereas the minority classes often have a very small number of samples. Data resampling has proven to be effective in alleviating such imbalanced settings, while feature selection is a commonly used technique for improving classification performance. However, the joint impact of feature selection and data resampling on two-class imbalance classification has rarely been addressed before. This work investigates the performance of two opposite imbalanced classification frameworks in which feature selection is applied before or after data resampling. We conduct a large-scale empirical study with a total of 9225 experiments on 52 publicly available datasets. The results show that both frameworks should be considered for finding the best performing imbalanced classification model. We also study the impact of classifiers, the ratio between the number of majority and minority samples (IR), and the ratio between the number of samples and features (SFR) on the performance of imbalance classification. Overall, this work provides a new reference value for researchers and practitioners in imbalance learning.

  • 50.
    Zhang, Hong
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. 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 pests2010Ingår i: Mathematical and computer modelling, ISSN 0895-7177, E-ISSN 1872-9479, Vol. 52, nr 1-2, s. 37-54Artikel i tidskrift (Refereegranskat)
    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.

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