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  • 1651.
    Wang, Yan
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Gaspes, Veronica
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    An embedded language for programming protocol stacks in embedded systems2011In: PEPM '11: proceedings of the 20th ACM SIGPLAN Workshop on Partial Evaluation and Semantics-Based Program Manipulation, January 24, 2011, Austin, Texas, USA, New York, NY, USA: ACM Press, 2011, p. 63-72Conference paper (Refereed)
    Abstract [en]

    Protocol stack specifications are well-structured documents that follow a number of conventions and notations that have proven very useful for the design and dissemination of communication protocols. Protocol stack implementations on the other hand, are done in low-level languages, using error-prone programming techniques resulting in programs that are difficult to relate to the specifications, difficult to maintain, modify, extend and reuse. To overcome these problems we propose a domain-specific language that provides abstractions close to the notations used in protocol specifications. From descriptions in our language we generate C programs that can be integrated with other systems software. The language provides constructs to describe packet formats, including physical layout, constraints and dependencies. It also provides constructs for state machines and for layering protocols into stacks. Experiments show that the C programs we generate are comparable in performance and binary size to hand-crafted C programs.

  • 1652.
    Wang, Yan
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Gaspes, Veronica
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Integrating a data description language with protocol stack development2009In: Proceedings of the IASTED International Conference on Modelling, Simulation, and Identification, MSI 2009 / [ed] H. Ma and S. Narayanan, Anaheim, Calif.: ACTA Press, 2009, p. 8-Conference paper (Refereed)
    Abstract [en]

    Communication software, most notoriously protocolstacks, are an area of growing interest. Many companiesimplement new or revised protocols for new applicationrequirements, and reimplement well-known infrastructureprotocol stacks to accomodate to new hardware andsoftware platforms. However, due to the complexity andperformance-critical nature of communication software,implementing protocol stacks remains a time-consumingand error-prone task with considerable impact on time tomarket, scalability and maintainance. The work at handinvestigates how to provide program development supportfor protocol stack implementation to make it easier andmore likely to be correct while respecting non-functionalconstraints. We present a language-based approach for theimplementation of protocol stacks. We define a domainspecificembedded language, IPS, for declaratively describingoverlaid protocol stacks. In IPS a high-level packetspecification is described using a data description languagewhich is compiled into a.) an internal data representation,and b.) packet processing functions in C. Both are then integratedinto the dataflow framework of a protocol overlayspecification. IPS generates highly portable C code for variousarchitectures from this source. We present the compilationframework for generating packet processing andprotocol logic code, and a preliminary evaluation.

  • 1653.
    Wecksten, Mattias
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    RealLife - en tekniköversikt2008Report (Other academic)
    Abstract [sv]

    RealLife är en sammankopplink mellan användarens plattform och tjänsteleverantörer via en central databas. Tanken är att en individidentifierare, UBI passport, ska vara kärnan i systemet som möjliggör att flytta innehåll från plattform till plattform. Genom att ta kontroll över den databas som samlar allt material och alla tjänster får man möjlighet att sälja extremfokuserad reklam. All den teknik som krävs för att genomföra projektet RealLife finns tillgänglig i någon form redan idag. Avgörande blir om man lyckas att göra så att användaren känner någon nytta utöver vad man skulle ha fått från en traditionell söktjänst. Detta kräver articifiell intelligens utöver vad som är tillgängligt idag.

  • 1654.
    Wecksten, Mattias
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Är du beredd? – för nu snor någon dina företagshemligheter!2008In: Hallands Affärer, no 3, p. 1-Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Populärvetenskapligt brandtal om nyttan och behovet av välutbildade nätverkstekniker med perspektiv på såväl teknik som juridik.

  • 1655.
    Wecksten, Mattias
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Less pessimistic worst-case delay analysis for packet-switched networks2008In: IEEE International Conference on Emerging Technologies and Factory Automation, 2008. ETFA 2008, Piscataway, N.J.: IEEE Press, 2008, p. 1213-1219Conference paper (Refereed)
    Abstract [en]

    The rapid growth of distributed real-time systems creates a need for cheap and available network solutions while still fulfilling the real-time requirements. In this paper we propose a method for less pessimistic delay analysis for packet switched first come first serve network, when knowing the intervals of possible message generation. Experiments show that the proposed method generates the expected results according to theoretical limitations of the experiment cases. The experiments also show that the proposed method could be practically used for non-trivial systems. Suggestions are given for future work on how to relax traffic requirements and how to cope with circular dependencies.

  • 1656.
    Wecksten, Mattias
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Vasell, Jonas
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Towards a tool for derivation of implementation constraints2004In: Ninth IEEE International Conference on Engineering Complex Computer Systems, 2004. Proceedings, Piscataway, N.J.: IEEE , 2004, p. 119-127Conference paper (Refereed)
    Abstract [en]

    An increasing concern in the development of embedded systems is that fundamental design problems often remain undetected until the final tests, after implementation and integration of all components, or maybe even later - at runtime. This is particularly important when it comes to meeting nonfunctional constraints such as performance or resource utilization requirements. Correcting problems with their sources in design, after implementation, may be very costly as it often requires both redesign and re-implementation. Therefore, much effort has been put into the development of methods and tools that help system designers and developers to detect problems as early as possible during system development. This paper contributes with an addition to that field by presenting and evaluating the practical usefulness of a method that makes it possible to detect problems in system design and dimensioning, even before all components of the system have been fully implemented. Evaluation of the proposed method has been done through 17 different case studies with different characteristics, focusing particularly on realtime latency requirements for tasks on homogeneous single bus platforms. The evaluation indicates a practical method that can be turned into a powerful tool. The presented principles can be extended to wider classes of constraints and systems.

  • 1657.
    Weckstén, Mattias
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Frick, Jan
    Halmstad University.
    Sjostrom, Andreas
    Halmstad University.
    Järpe, Eric
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    A Novel Method for Recovery from Crypto Ransomware Infections2016In: 2016 2nd IEEE International Conference on Computer and Communications, ICCC 2016 - Proceedings, New York: IEEE, 2016, p. 1354-1358Conference paper (Refereed)
    Abstract [en]

    Extortion using digital platforms is an increasing form of crime. A commonly seen problem is extortion in the form of an infection of a Crypto Ransomware that encrypts the files of the target and demands a ransom to recover the locked data. By analyzing the four most common Crypto Ransomwares, at writing, a clear vulnerability is identified; all infections rely on tools available on the target system to be able to prevent a simple recovery after the attack has been detected. By renaming the system tool that handles shadow copies it is possible to recover from infections from all four of the most common Crypto Ransomwares. The solution is packaged in a single, easy to use script. © 2016 IEEE.

  • 1658.
    Weckstén, Mattias
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Vasell, J.
    Generic Systems Sweden AB.
    Derivation of implementation constraints - implementation simulation and treatment of multiple design choices2005In: Proceedings: 10th IEEE International Conference on Engineering of Complex Computer Systems, ICECCS 2005, 16-20 June 2005, Shanghai, China, Los Alamitos, Calif.: IEEE Computer Society, 2005, p. 459-466Conference paper (Refereed)
    Abstract [en]

    The industrial use of ad hoc implementation methods for non-functional constrained tasks has resulted in unnecessary expensive projects. In some cases, ad hoc methods result in overly many iterations to be made and in some severe cases, total project breakdown. To be able to solve these problems a method has been developed to derive end-to-end non-functional constraints, such as timing requirements, to task-level constraints and to promote this information to the implementation phase of the project. For a tool, as the one described above, to be really useful it is important to be able to show that there is a potential cost reduction to be made. To be able to show that a certain implementation method costs less in work hours than to use an ad hoc implementation method, a model for implementation simulation with support for multiple implementation alternatives has been developed. The experiments show that using the budget based implementation method leads to a significant cost reduction in most cases, compared to the ad hoc method. As far as we know, no similar experiments have been done to compare implementation methods.

  • 1659.
    Weckstén, Mattias
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Vasell, Jonas
    Generic Systems Sweden AB, Stockholm, Sweden.
    Derivation of implementation constraints – implementation simulation and treatment of multiple design choices2007In: Proc. of the 9th biennial SNART Conference on Real-Time Systems (Real-Time in Sweden – RTiS’07), Västerås, Sweden, Aug. 21-22, 2007, p. 21-28Conference paper (Refereed)
    Abstract [en]

    The industrial use of ad hoc implementation methods for non-functional constrained tasks has resulted in unnecessary expensive projects. In some cases, ad hoc methods result in overly many iterations to be made and in some severe cases, total project breakdown. To be able to solve these problems a method has been developed to derive end-to-end non-functional constraints, such as timing requirements, to task-level constraints and to promote this information to the implementation phase of the project. For a tool, as the one described above, to be really useful it is important to be able to show that there is a potential cost reduction to be made. To be able to show that a certain implementation method costs less in work hours than to use an ad hoc implementation method, a model for implementation simulation with support for multiple implementation alternatives has been developed. The experiments show that using the budget based implementation method leads to a significant cost reduction in most cases, compared to the ad hoc method. As far as we know, no similar experiments has been done to compare implementation methods.

  • 1660.
    Weckstén, Mattias
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Vassell, Jonas
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    A tool for derivation of implementation constraints: – evaluation using implementation simulation2004In: RTSS 2004 WIP Proceedings, The 25th IEEE International Real-Time Systems Symposium, IEEE , 2004, p. 4-Conference paper (Refereed)
    Abstract [en]

    The industrial use of ad hoc implementation methods for non-functional constrained tasks has sometimes resulted in unnecessary expensive projects. In some cases, ad hoc methods result in overly many iterations to be made and in some severe cases, total project breakdown. To be able to solve these problems a new method has been developed to derive end-to-end non-functional constraints, such as performance or resource utilization requirements, to task-level constraints and to promote this information to the implementation phase of the project. For a tool to be really useful it is important to be able to show the usability and potential cost reduction. To be able to show that a certain implementation method costs less in work hours than to use an ad hoc implementation method, a model for implementation simulation has been developed. As far as we know, no similar experiments has been done to compare implementation methods.

  • 1661.
    Wehrmeister, Marco A.
    et al.
    Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
    Pignaton de Freitas, Edison
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Pereira, Carlos E.
    Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
    An Infrastructure for UML-Based Code Generation Tools2009In: Analysis, architectures and modelling of embedded systems: Third IFIP TC 10 International Embedded Systems Symposium, IESS 2009, Langenargen, Germany, September 14-16, 2009, proceedings / [ed] Rettberg, A Zanella, MC Rammig, FJ, New York: Springer-Verlag New York, 2009, p. 32-43Conference paper (Refereed)
    Abstract [en]

    The use of Model-Driven Engineering (MDE) techniques in the domain of distributed embedded real-time systems are gain importance in order to cope with the increasing design complexity of such systems. This paper discusses an infrastructure created to build GenERTiCA, a flexible tool that supports a MDE approach, which uses aspect-oriented concepts to handle nonfunctional requirements from embedded and real-time systems domain. GenERTiCA generates source code from UML models, and also performs weaving of aspects, which have been specified within the UML model. Additionally, this paper discusses the Distributed Embedded Real-Time Compact Specification (DERCS), a PIM created to support UML-based code generation tools. Some heuristics to transform UML models into DERCS, which have been implemented in GenERTiCA, are also discussed.

  • 1662.
    Wehrmeister, Marco A.
    et al.
    Instituto de Informática, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Pignaton de Freitas, Edison
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Instituto de Informática, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Pereira, Carlos E.
    Dep. Engenharia Elétrica, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Using GenERTiCA to generation code from RT-UML: A case study2009In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 13, no PART 1, p. 674-679Article in journal (Refereed)
    Abstract [en]

    Tool support is essential to allow the use of Model-Driven Engineering (MDE) in the design of distributed embedded real-time systems. GenERTiCA is a flexible tool that supports a MDE approach, which uses concepts of Aspect-Oriented Development (AOD) to handle non-functional requirements from real-time and embedded systems domain. This paper presents a comprehensive case study that illustrates GenERTiCA usage to generate source code from UML models. GenERTiCA also performs aspects weaving using aspect’s information specified in UML models. Results regarding source code generation for a Java platform based on the Real-Time Specification for Java (RTSJ) are presented. Additionally, this paper discusses the implementation of some aspects of a high-level aspects framework, named DERAF, using the mentioned platform. © 2009 IFAC.

  • 1663.
    Weman Josefsson, Karin
    et al.
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Ebbesson, Esbjörn
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Halila, Fawzi
    Halmstad University, School of Business, Engineering and Science, Centre for Innovation, Entrepreneurship and Learning Research (CIEL).
    Johnson, Urban
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI), Sport Health and Physical activity.
    Lund, Jesper
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Wickström, Nicholas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Wärnestål, Pontus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Application of self-determination theory in the e-health industry – promoting sustainable exercise motivation2015In: Proceeding: 14th European Congress of Sport Psychology: Sport Psychology: Theories and Applications for Performance, Health and Humanity: 14-19 July 2015, Bern, Switzerland / [ed] Olivier Schmid & Roland Seiler, Bern: University of Bern , 2015, p. 372-372Conference paper (Refereed)
    Abstract [en]

    Developing tailored digital interventions for exercise motivation by applying behavioral theory into existing web services in cooperation with the e-health industry could create a mutual base for experience exchange and practical implications. It could also add higher standards to e-health business by providing a scientifically sound and trustworthy foundation for digital solutions. This project aims to design an interactive tool grounded in sport and exercise psychology and combined with the latest expertise from information technology and innovation science, considering e-health industrial requirements and user needs. A main objective is to test the efficacy of using Self-Determination Theory (SDT) in designing, constructing and evaluating an exercise intervention. The digital intervention is based on a literature review mapping exercise motivation related to self-determination theory, complemented by qualitative cross-disciplinary interaction design methodologies, such as qualitative analysis of interviews and contextual observation capturing participant goals, behaviour, preferences, attitudes and frustrations. Intervention contents are essentially autonomy supportive structures, goal-setting support and relapse prevention, self-regulation structures, health information and web links. In February 2015 the intervention prototype will be pilot tested in a randomized controlled trial (RCT), involving existing members and clients (N > 10 000) of two health service companies. Outcomes relate to self-determined exercise motivation (The Basic Psychological Needs in Exercise Scale and The Behavioral Regulation in Exercise Questionnaire-2) and exercise behaviour, measured both by self-report measures (Godin Leisure-Time Exercise Questionnaire) and step counters. The RCT contains three measure points in order to allow advanced analyses of change and mechanisms based on the SDT-process model and motivational profiles. Latent growth curve and structural equation models will primarily be used to analyse data. This pilot study will create a baseline for elaboration into a second phase, were the digital tool will be further developed and longitudinally tested and evaluated over a nine months period. © 2015 University of Bern, Institut of Sport Science 

  • 1664.
    Weman Josefsson, Karin
    et al.
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI). University of Gothenburg, Gothenburg, Sweden.
    Halila, Fawzi
    Halmstad University, School of Business, Engineering and Science, Centre for Innovation, Entrepreneurship and Learning Research (CIEL).
    Johnson, Urban
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Lindwall, Magnus
    University of Gothenburg, Gothenburg, Sweden.
    Wickström, Nicholas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Wärnestål, Pontus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Digital innovations and self-determined exercise motivation: a person-centred perspective2014In: Vitalis – Nordens ledande eHälsomöte 2014: Vetenskapliga papers presenterade vid Vitalis konferens, Svenska Mässan, Göteborg, 8-10 april 2014, Göteborg: Vitalis & Sahlgrenska akademin, Göteborgs universitet , 2014, p. 22-25Conference paper (Refereed)
    Abstract [en]

    Health care costs are increasing twice as fast as wealth, making health promotion and development of cost-effective care increasingly important in order to generate sustainable health care solutions. E-health, applications and interactive tools for exercise promotion flourish; but despite this and an overflow of information regarding health benefits of regular physical activity, exercise adherence has proven to be a significant challenge. This article concerns a project aimed to design an interactive tool based on comprehensive knowledge from the field of psychology combined with expertise from information technology and innovation, based on e-health industrial requirements and user needs. The research group will, together with the expertise and infrastructure of the collaborating companies Health Profile Institute AB and Tappa Service AB, support and progress an existing PhD-project on digital interventions in exercise motivation. This will be done by designing; applying and evaluating a person-centred digital intervention prototype for exercise motivation and adherence enhancement based on Self-Determination Theory.

  • 1665.
    Weman Josefsson, Karin
    et al.
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Halila, Fawzi
    Halmstad University, School of Business, Engineering and Science, Centre for Innovation, Entrepreneurship and Learning Research (CIEL).
    Johnson, Urban
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI), Sport Health and Physical activity.
    Wickström, Nicholas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Wärnestål, Pontus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Digital interventions in self-determined exercise motivation – interdisciplinary innovations2015In: ISBNPA 2015: Advancing Behavior Change Science : 3rd – 6th June 2015: Abstract Book, 2015, p. 592-592Conference paper (Refereed)
    Abstract [en]

    Purpose:There is a need for scientifically sound and theory based tools and services in e-health. In this project knowledge from the field of psychology will be complemented by expertise in information technology and innovation science in designing a digital intervention based on Self-determination theory (SDT) aiming to facilitate exercise motivation.

    Methods:The intervention will be tested by a three wave RCT design in a population of e-health clients (n = 200) in a web based exercise service. Sensors (step counters) and self-reports (Godin Leisure-Time Exercise Questionnaire) will be used to measure objective and subjective exercise behavior while instruments based on SDT (Basic Psychological Needs in Exercise Scale and Behavioral Regulation in Exercise Questionnaire-2 ) will measure factors related to motivation.  Advanced mediation variable analyses (MVA) and latent growth curve models (LGCM) will be used to explore motivational processes, changes and profiles in relation to exercise behavior.

    Expected Results:Based on the SDT process model, it is hypothesized that a (digital) environment supporting basic psychological need satisfaction will facilitate internalization and enhanced self-determined motivation, which in turn will have a positive effect on exercise behavior.

    Conclusions:Clarifying mechanisms and indirect effects provide knowledge of how intervention effects could be interpreted and understood. Combining high level research design like RCT and advanced analyses as MVA provides valuable contributions to the understanding of theoretical mechanisms of motivation that could inform the tailoring of effective interventions promoting healthy exercise behaviours.  In addition, the project might form a prosperous interdisciplinary fusion generating innovative and theory based digital solutions for e-health.

  • 1666.
    Weman-Josefsson, Karin Anna
    et al.
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI), Sport Health and Physical activity. University of Gothenburg, Gothenburg, Sweden.
    Halila, Fawzi
    Halmstad University, School of Business, Engineering and Science, Centre for Innovation, Entrepreneurship and Learning Research (CIEL).
    Johnson, Urban
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI), Sport Health and Physical activity.
    Wickström, Nicholas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Wärnestål, Pontus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Digital Innovations and Self-determined exercise motivation: an interdisciplinary approach2015In: Proceedings of The 6th International Multi-Conference on Complexity, Informatics and Cybernetics: IMCIC March 2015. Orlando, Florida., 2015Conference paper (Refereed)
    Abstract [en]

    In face of escalating health care costs, new technology holds great promise for innovative solutions and new, more sustainable health care models. Technology centers around the individual, allowing for greater autonomy and control in health issues and access to tailored information and customized health behavior interventions. While this offers good opportunities for both public health impact and improved well-being at individual levels, it also emphasizes the need for properly designed e-health models firmly based on scientific principles and adequate theoretical frameworks. Consequently, this project aims to design an interactive tool utilizing an interdisciplinary approach combining motivational theory with the fields of information technology and business model innovation. In collaboration with two companies from the e-health industry, the purpose is to design, apply and evaluate a person-centered interactive prototype for maintainable and self-determined exercise motivation.

  • 1667.
    Weman-Josefsson, Karin
    et al.
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Wärnestål, Pontus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Johnson, Urban
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Halila, Fawzi
    Halmstad University, School of Business, Engineering and Science, Centre for Innovation, Entrepreneurship and Learning Research (CIEL).
    Wickström, Nicholas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    An interdisciplinary project plan on Digital Innovations and Self-determined Exercise Motivation2013Conference paper (Other academic)
  • 1668.
    Wiberg, Per-Arne
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Graphical programming of time-deterministic real-time systems1996In: Second IEEE International Conference on Engineering of Complex Computer Systems: Held jointly with 6th CSESAW, 4th IEEE RTAW, and SES'96, Montréal, Québec, Canada, October 21-25, 1996, Los Alamitos, Calif.: IEEE Computer Society, 1996, p. 173-180Conference paper (Other academic)
    Abstract [en]

    In this paper we present the Picasso programming language and the underlying design philosophy. Our goal is to provide programmers working with distributed embedded real-time systems with a tool to manage the complexity of this class of systems. The proposed tool allows easy and safe changes of the system software and hardware at any time during the lifetime of the system. This means that even during operation the system can be changed safely. This is not only important for enhancing the design process but is also necessary for a class of systems that need to be in service at all times. We have chosen to call this approach Change-Orientation. The most characteristic properties of the language are that it is graphical and that it shows time explicitly. All processing is described as functional transformations. These transformations are called processes. A very direct way of implementing a process is possible because the semantics of the description maps directly on the computation model of the processor.

  • 1669.
    Wiberg, Per-Arne
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS). Free2move AB.
    Bilstrup, Urban
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS). Free2move AB.
    Wireless Technology in Industry – Applications and User Scenarios2001In: 2001 8th IEEE International Conference on Emerging Technologies and Factory Automation: Proceedings: ETFA 2001, October 15-18, 2001, Antibes-Juan les Pins, France, vol. 1, Piscataway, NJ: IEEE Press, 2001, p. 123-131Conference paper (Refereed)
    Abstract [en]

    In this paper we draw a map of the wireless technology landscape, and place different industrial applications in this context. It is clear that in order to implement wireless communication in safety critical applications more research is needed. We describe one approach aiming at the very low bit error rates of these applications.

  • 1670.
    Wickström, Nicholas
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Byttner, Stefan
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Hellring, Magnus
    Volvo Technology Corporation, Gothenburg, Sweden.
    Rögnvaldsson, Thorsteinn
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Neural networks for extracting the pressure peak position from the ion current2004In: Virtual sensing of combustion quality in SI engines using the ion current, Göteborg: Chalmers tekniska högskola , 2004, p. 95-110Chapter in book (Other academic)
  • 1671.
    Wickström, Nicholas
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent Systems´ laboratory.
    Byttner, Stefan
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent Systems´ laboratory.
    Holmberg, Ulf
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Intelligent Systems´ laboratory.
    Robust tuning of Individual Cylinders AFR in SI Engines with the Ion Current2005In: SAE Transactions, ISSN 0096-736X, Vol. 114, no 03, p. 48-52Article in journal (Refereed)
    Abstract [en]

    A method for robust tuning of individual cylinders air-fuel ratio is proposed. The fuel injection is adjusted so that each cylinder has the same air-fuel ratio in inner control loops, and the resulting air-fuel ratio in the exhaust pipe is controlled with an exhaust gas oxygen sensor (EGO) in an outer control loop to achieve stoichiometric air-fuel ratio. Correction factors to provide cylinder individual fuel injection timing are calculated based on measurements of the ion currents for the individual cylinders. An implementation in a production vehicle is shown with results from driving on the highway. © 2005 SAE International.

  • 1672.
    Wickström, Nicholas
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Larsson, Magnus
    Mecel AB, Åmål, Sweden.
    Taveniku, Mikael
    Chalmers University of Technology, Göteborg, Sweden.
    Linde, Arne
    Chalmers University of Technology, Göteborg, Sweden.
    Svensson, Bertil
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS). Chalmers University of Technology, Göteborg, Sweden.
    Neural Virtual Sensors — Estimation of Combustion Quality in SI Engines using the Spark Plug1998In: ICANN 98: Proceedings of the 8th International Conference on Artificial Neural Networks, Skövde, Sweden, 2-4 September 1998 / [ed] Lars Niklasson, Mikael Bodén, Tom Ziemke, London: Springer , 1998, p. 215-220Conference paper (Refereed)
    Abstract [en]

    We propose two virtual sensors which estimate the location of the pressure peak and the air-fuel ratio from measurements of the ionization current across the spark plug gap.

    The location of pressure peak virtual sensor produces estimates on a cycle-by-cycle basis for each of the cylinders. These estimates are twice as good as estimates obtained from a linear model.

    The air-fuel ratio virtual sensor uses the universal exhaust gas oxygen sensor as reference; it produces estimates that are ten times better than estimates obtained from a linear model.

  • 1673.
    Wikhamn, Björn Remneland
    et al.
    Department of Business Administration, School of Business, Economics and Law, University of Gothenburg, Sweden.
    Ljungberg, Jan
    Department of Applied IT, University of Gothenburg, Sweden.
    Rolandsson, Bertil
    Department for Sociology and Work Science, University of Gothenburg, Sweden.
    Bergquist, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Given enough eyeballs, all crimes are shallow – The organizing of citizen collaboration to solve an online detective story2019In: Journal of Technology Management & Innovation, ISSN 0718-2724, E-ISSN 0718-2724, Vol. 14, no 2, p. 59-68Article in journal (Refereed)
    Abstract [en]

    This paper theorizes about the organizing of online citizen collaboration. The setting is an Internet forum where people started their own investigations about a crime of animal cruelty. The concepts of commons-based peer production and generativity are utilized to analyse the complex organizing mechanisms of voluntaristic online collaboration in practice. Three general functions are introduced - operational, managerial, and noise - which are intertwined and together make up important basis for organizing generativity. © Universidad Alberto Hurtado, Facultad de Economía y Negocios.

  • 1674.
    Wiklund, Daniel
    et al.
    Institutionen för material- och tillverkningsteknik, Tillverkningsteknik, Chalmers tekniska högskola.
    Nilsson, Larsgunnar
    Nilsson, Bertil
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Andersson, Alf
    Rosén, Bengt Göran
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Functional Surfaces.
    Gunnarsson, Lars
    On the Implementation and Evaluation of a Roughness Based Friction Model in FE Simulations of Sheet Metal Forming2006In: Proceedings of The 12th Nordic Symposium on Tribology, Lyngby: DTU Mechanical Engineering , 2006Conference paper (Refereed)
  • 1675.
    Wildevuur, Sabine
    et al.
    Waag Society, Amsterdam, The Netherlands.
    van Dijk, Dick
    Waag Society, Amsterdam, The Netherlands.
    Hammer-Jakobsen, Thomas
    Copenhagen Living Lab, Valby, Denmark.
    Bjerre, Mie
    Copenhagen Living Lab, Valby, Denmark.
    Äyväri, Anne
    Laurea University of Applied Science, Porvoo, Finland.
    Lund, Jesper
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Connect: Design for an Empathic Society2013Book (Other (popular science, discussion, etc.))
    Abstract [en]

    The prospects are clear: we will probably live longer. The number of people aged 65 and up will increase enormously over the next few decades. Society will change as a result, but in what manner?

    Europe - and, in fact, probably the world - faces the challenge of preventing loneliness and isolation amongst a growing group of senior people. The oldest part of the population is at particular risk of becoming isolated and lonely as they grow older and their work-related networks erode. While working in the field of technology and aging, the authors discovered that there is a whole new field to be explored, namely the phenomenon of connectedness.

    This book is written by a group of authors with very different backgrounds, varying from business, ICT, marketing, anthropology, medicine, design and computer interaction. They all felt the urge to explore this field of connectedness and they discovered new opportunities for the emerging market of ‘aging-driven design’.

    By unfolding the very nature of relationships and age-based transitions in life, the authors invite the reader to join them in an effort to design for connectedness: to reframe the picture, rethink our options and reinvent how to connect!

  • 1676.
    Willa, K.
    et al.
    Argonne National Laboratory, Argonne, Illinois, USA.
    Diao, Zhu
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab. Stockholm University, Stockholm, Sweden.
    Campanini, D.
    Stockholm University, Stockholm, Sweden.
    Welp, U.
    Argonne National Laboratory, Argonne, Illinois, USA.
    Divan, R.
    Argonne National Laboratory, Argonne, Illinois, USA.
    Hudl, M.
    Stockholm University, Stockholm, Sweden.
    Islam, Z.
    Argonne National Laboratory, Argonne, Illinois, USA.
    Kwok, W.-K.
    Argonne National Laboratory, Argonne, Illinois, USA.
    Rydh, A.
    Stockholm University, Stockholm, Sweden.
    Nanocalorimeter platform for in situ specific heat measurements and x-ray diffraction at low temperature2017In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 88, no 12, article id 125108Article in journal (Refereed)
    Abstract [en]

    Recent advances in electronics and nanofabrication have enabled membrane-based nanocalorimetry for measurements of the specific heat of microgram-sized samples. We have integrated a nanocalorimeter platform into a 4.5 T split-pair vertical-field magnet to allow for the simultaneous measurement of the specific heat and x-ray scattering in magnetic fields and at temperatures as low as 4 K. This multi-modal approach empowers researchers to directly correlate scattering experiments with insights from thermodynamic properties including structural, electronic, orbital, and magnetic phase transitions. The use of a nanocalorimeter sample platform enables numerous technical advantages: precise measurement and control of the sample temperature, quantification of beam heating effects, fast and precise positioning of the sample in the x-ray beam, and fast acquisition of x-ray scans over a wide temperature range without the need for time-consuming re-centering and re-alignment. Furthermore, on an YBa2Cu3O7−δ crystal and a copper foil, we demonstrate a novel approach to x-ray absorption spectroscopy by monitoring the change in sample temperature as a function of incident photon energy. Finally, we illustrate the new insights that can be gained from in situ structural and thermodynamic measurements by investigating the superheated state occurring at the first-order magneto-elastic phase transition of Fe2P, a material that is of interest for magnetocaloric applications. © 2017 Author(s).

  • 1677.
    Willander, Magnus
    et al.
    Linköping University, Linköping, Sweden.
    Pettersson, Håkan
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Preface2017In: International Journal of High Speed Electronics and Systems, ISSN 0129-1564, Vol. 26, no 1-2, article id 1702001Article in journal (Refereed)
  • 1678.
    Willander, Magnus
    et al.
    Linköping University, Linköping, Sweden.
    Pettersson, HåkanHalmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), MPE-lab.
    Special Issue on Scaling and Integration of High Speed Electronics and Optomechanical Systems2017Conference proceedings (editor) (Refereed)
  • 1679.
    Willig, Andreas
    et al.
    Department of Computer Science and Software Engineering, University of Canterbury, Christchurch, New Zealand.
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Deadline-Aware Scheduling of Cooperative Relayers in TDMA-Based Wireless Industrial Networks2014In: Wireless networks, ISSN 1022-0038, E-ISSN 1572-8196, Vol. 20, no 1, p. 73-88Article in journal (Refereed)
    Abstract [en]

    In this paper we consider a scenario in which a set of source nodes wishes to transmit real-time data packets periodically to a central controller over lossy wireless links, while using a TDMA-based medium access control protocol. Furthermore, a number of relay nodes are present which can help the source nodes with packet retransmissions. The key question we consider in this paper is how to schedule the TDMA slots for retransmissions while taking advantage of the relay nodes, so that the average number of packets missing their deadlines is minimized. We provide a problem formulation for the general deadline-aware TDMA relay scheduling problem. Since the design space of the general problem is large, we also present one particular class of restricted TDMA relay scheduling problems. We suggest and numerically investigate a range of algorithms and heuristics, both optimal and suboptimal, of the restricted scheduling problem, which represent different trade-offs between achievable performance and computational complexity. Specifically, we introduce two different Markov Decision Process (MDP) based formulations for schedule computation of the restricted TDMA relay scheduling problem. One MDP formulation gives an optimal schedule, another (approximate) formulation gives a sub-optimal schedule which, however, comes very close to the optimal performance at much more modest computational and memory costs. © 2013 Springer Science+Business Media New York.

  • 1680.
    Willig, Andreas
    et al.
    University of Canterbury, Christchurch, New Zealand.
    Uhlemann, Elisabeth
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    On relaying for wireless industrial communications: Is careful placement of relayers strictly necessary?2012In: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS, Piscataway, NJ: IEEE Press, 2012, p. 191-200, article id 6242567Conference paper (Refereed)
    Abstract [en]

    Relaying is a very promising technique to improve the reliability of data transmission in wireless (industrial) networks. With relaying, relay nodes support source nodes in carrying out retransmissions. A common assumption is that relayers should be placed at “good” positions (e.g. in the middle between source and destination) to achieve benefits. In this paper we tackle the question of whether it is strictly necessary to place relayers at “good” positions (which often requires extensive measurements). We present results indicating that the benefits of relaying are achievable even with randomly placed relayers, as long as enough of them are deployed. Specifically, we present results suggesting that with a sufficient (and still not too high) number of randomly deployed relayers, the probability that all packets, sent by source nodes to a central controller in a TDMA round, reach the controller is larger than for the case with source-only retransmissions. This finding holds true both in the absence and the presence of feedback. © 2012 IEEE.

  • 1681.
    Willig, Andreas
    et al.
    Technische Universitt Berlin, Berlin, Germany.
    Uhlemann, Elisabeth
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    PRIOREL-COMB: A protocol framework supporting relaying and packet combining forwireless industrial networking2008In: WFCS 2008: 2008 IEEE International Workshop on Factory Communication Systems : proceedings : May 21st-23rd, 2008, Steigenberger Hotel de Saxe, Dresden, Germany / [ed] Gianluca Cena and Françoise Simonot-Lion, Piscataway, NJ: IEEE Press, 2008, p. 45-54Conference paper (Refereed)
    Abstract [en]

    The PRIOREL-COMB framework presented here integrates support for relaying and packet combining into wireless industrial networks. The selection of suitable relay nodes is made using distributed algorithms which includes different eligibility tests as well as different priority assignments. The framework improves performance in terms of probability to successfully deliver packets before their deadline and it can be implemented on top of commercial transceivers without modification of the physical layer. This class of protocols will therefore be a valuable addition to future wireless industrial communication systems.

  • 1682.
    Wolkerstorfer, M.
    et al.
    FTW, Österrike.
    Nordström, Tomas
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Coverage Optimization in DSL Networks by Low-Complexity Discrete Spectrum Balancing2011Conference paper (Refereed)
    Abstract [en]

    Spectrum balancing is an established optimization approach in multi-carrier digital subscriber line (DSL) systems. It has previously been applied to very different performance objectives such as sum-rate, min-rate, or fairness maximization and sum-power minimization. In this work we study the maximization of the service coverage, which will be defined as the number of DSL lines which can be granted an operator-specified high-bandwidth service. The proposed algorithm is based on a previously described mathematical decomposition framework. We extend this framework for our new problem and enhance its scalability by various low-complexity heuristics. Simulations demonstrate the applicability of our algorithm for DSL networks of realistic sizes. More precisely, our results obtained in thousand 25 user near-far DSL scenarios show an average gain in service coverage of more than 13% compared to state-of-the-art sum-rate maximizing spectrum balancing algorithms. © 2011 IEEE.

  • 1683.
    Wolkerstorfer, Martin
    et al.
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Jaldén, Joakim
    ACCESS Linnaeus Center, Signal Processing Lab, KTH Royal Institute of Technology, Stockholm, Sweden.
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Column Generation for Discrete-Rate Multi-User and Multi-Carrier Power Control2012In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 60, no 9, p. 2712-2722Article in journal (Refereed)
    Abstract [en]

    We consider a constrained multi-carrier power allocation problem in interference-limited multi-user systems with a finite set of transmission rates. The Lagrange relaxation is a common technique for decomposing such problems into independently solvable per-subcarrier problems. Deviating from this approach our main contribution is the proposal of a novel spectrum management framework based on a Nonlinear Dantzig-Wolfe problem decomposition. It allows for suboptimal initialization and suboptimal power allocation methods with low complexity. While we show that the combinatorial per-subcarrier problems have polynomial complexity in the number of users, we find that such suboptimal methods are indispensable in large systems. Thus we give an overview of various basic dual heuristics and provide simulation results on a set of thousand digital subscriber line (DSL) networks which show the superior performance of our framework compared to previous power control algorithms. © 2012 IEEE.

  • 1684.
    Wolkerstorfer, Martin
    et al.
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Jaldén, Joakim
    KTH, Stockholm, Sverige.
    Nordström, Tomas
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Low-Complexity Optimal Discrete-Rate Spectrum Balancing in Digital Subscriber Lines2013In: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 93, no 1, p. 23-34Article in journal (Refereed)
    Abstract [en]

    Discrete-rate spectrum balancing in interference-limited multi-user and multi-carrier digital subscriber lines (DSL) is a large-scale, non-convex and combinatorial problem. Previously proposed algorithms for its (dual) optimal solution are only applicable for networks with few users, while the suboptimality of less complex bit-loading algorithms has not been adequately studied so far. We deploy constrained optimization techniques as well as problem-specific branch-and-bound and search-space reduction methods, which for the first time give a low-complexity guarantee of optimality in certain multi-user DSL networks of practical size. Simulation results precisely quantify the suboptimality of multi-user bit-loading schemes in a thousand ADSL2 scenarios under measured channel data.

  • 1685.
    Wolkerstorfer, Martin
    et al.
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Comparative Simulation Study of Fast Heuristics for Power Control in Copper Broadband Networks2014In: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 104, no November 2014, p. 437-449Article in journal (Refereed)
    Abstract [en]

    The data-rate in currently deployed multi-carrier digital subscriber line (DSL) communication systems is limited by the interference among copper lines. This interference can be alleviated by multi-user transmit power allocation. Problem decomposition results in a large number of per-subcarrier problems. Our objective is to solve these nonconvex integer per-subcarrier power control problems at low complexity. For this purpose we develop ten combinatorial heuristics and test them by simulation under a small complexity budget in scenarios with tens of DSL users, where optimal solutions are currently intractable. Simulation results lead us to the conclusion that simple randomized greedy heuristics extended by a specific local search perform well despite the stringent complexity restriction. This has implications on multi-user discrete resource allocation algorithms, as these can be designed to jointly optimize transmit power among users even in large-scale scenarios.

  • 1686.
    Wolkerstorfer, Martin
    et al.
    FTW, Austria.
    Nordström, Tomas
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Krasniqi, Bujar
    Vienna University of Technology.
    Wrulich, Martin
    Vienna University of Technology.
    Mecklenbräuker, Christopher
    Vienna University of Technology.
    OFDM/OFDMA Subcarrier Allocation2011In: Cross Layer Designs in WLAN Systems / [ed] N. Zorba, C. Skianis and C. Verikoukis, Troubador Publishing Ltd, 2011, p. 161-192Chapter in book (Other academic)
  • 1687.
    Wolkerstorfer, Martin
    et al.
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Statovci, Driton
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Enabling Greener DSL Access Networks by their Stabilization with Artificial Noise and SNR Margin2013In: Cluster Computing, ISSN 1386-7857, E-ISSN 1573-7543, Vol. 16, no 3, p. 407-419Article in journal (Refereed)
    Abstract [en]

    Low-power modes (LPM) are a standardized means in asymmetric digital subscriber lines (ADSL) 2 for reducing the power consumption at the central office. However, the activation of LPMs is hampered by the operators’ concern for instability introduced by frequent transmit power changes. The injection of artificial noise (AN) has been proposed as a standard-compliant stabilization technique. We develop an analytical solution for setting the AN power spectrum. Based on this solution we jointly optimize the AN power spectrum and the signal-to-noise ratio (SNR) margin. Simulation results show the performance gain in terms of rate and energy compared to heuristic rules for setting the AN power spectrum. We propose and demonstrate three approaches for evaluating the performance of AN-enabled DSL systems, including (a) joint spectrum balancing, AN, and margin optimization, (b) single-user worst-case-stable optimization, and (c) worst-case-stable optimization based on sequential initialization. Simulation results confirm a strong dependency of the performance under AN on the selected SNR margins, and highlight the total AN power consumption as well as the residual energy savings under low-power modes stabilized by AN. © 2012 The Author(s).

  • 1688.
    Wolkerstorfer, Martin
    et al.
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Statovci, Driton
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Energy-saving by Low-Power Modes in ADSL22012In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 56, no 10, p. 2468-2480Article in journal (Refereed)
    Abstract [en]

    The large number of broadband users and its forecast growth has recently triggered research on energy-efficiency in digital subscriber lines (DSLs). A promising technique are low-power modes (LPMs) as standardized in asymmetric DSL 2 (ADSL2) which let the DSL connection operate in downstream direction with reduced transmit rate and power. We study the problem of optimizing the LPM rate-level for energy-efficiency. A traffic-independent rate setting is proposed based on an analytical competitive framework. Also, a Markov chain based LPM model is derived which facilitates the fast numerical optimization of the LPM rate-level under realistic traffic models and system constraints. Simulation results under various traffic settings and DSL scenarios demonstrate energy savings by LPMs of around 30–40% of the ADSL2 transceiver’s power consumption. Furthermore, they provide insights on how to set the LPM rate-levels in practice for energy-efficient DSL operation. © 2012 Elsevier B.V. All rights reserved.

  • 1689.
    Wolkerstorfer, Martin
    et al.
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Trautmann, Steffen
    Lantiq A GmbH, Villach, Austria.
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Putra, Bakti
    FTW Telecommunications Research Center Vienna, Vienna, Austria.
    Modeling and Optimization of Line-Driver Power Consumption in xDSL Systems2012In: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2012, article id 226Article in journal (Refereed)
    Abstract [en]

    Optimization of the power spectrum alleviates the crosstalk noise in Digital Subscriber Lines (DSL) and thereby reduces their power consumption at present. In order to truly assess the DSL system power consumption, thispaper presents realistic line driver (LD) power consumption models. These are applicable to any DSL system andextend previous models by parameterizing various circuit-level non-idealities. Based on the model of a class-ABLD we analyze the multi-user power spectrum optimization problem and propose novel algorithms for its global or approximate solution. The thereby obtained simulation results support our claim that this problem can besimplified with negligible performance loss by neglecting the LD model. This motivates the usage of established spectral optimization algorithms, which are shown to significantly reduce the LD power consumption comparedto static spectrum management.

  • 1690.
    Wu, Jinfeng
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Lv, Gaofei
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Embedded Systems (CERES).
    Evaluation of Multicore Cache Architecture for Radar Signal Processing2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 1691.
    Wu, Phillip M.
    et al.
    Division of Solid State Physics and the Nanometer Structure Consortium (NmC at LU), Lund University, P.O. Box 118, 221 00 Lund, Sweden.
    Paschoal Jr., Waldomiro
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Kumar, Sandeep
    Division of Solid State Physics and the Nanometer Structure Consortium (NmC at LU), Lund University, P.O. Box 118, 221 00 Lund, Sweden.
    Borschel, Christian
    Institute for Solid State Physics, Jena University, Max-Wien-Platz 1, 07743 Jena, Germany.
    Ronning, Carsten
    Institute for Solid State Physics, Jena University, Max-Wien-Platz 1, 07743 Jena, Germany.
    Canali, Carlo M.
    Division of Physics, School of Computer Science, Linnæus University, 39233 Kalmar, Sweden.
    Samuelson, Lars
    Division of Solid State Physics and the Nanometer Structure Consortium (NmC at LU), Lund University, P.O. Box 118, 221 00 Lund, Sweden.
    Pettersson, Håkan
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Linke, Heiner
    Division of Solid State Physics and the Nanometer Structure Consortium (NmC at LU), Lund University, P.O. Box 118, 221 00 Lund, Sweden.
    Thermoelectric Characterization of Electronic Properties of GaMnAs Nanowires2012In: Journal of Nanotechnology, ISSN 1687-9503, E-ISSN 1687-9511, Vol. 2012, article id 480813Article in journal (Refereed)
    Abstract [en]

    Nanowires with magnetic doping centers are an exciting candidate for the study of spin physics and proof-of-principle spintronics devices. The required heavy doping can be expected to have a significant impact on the nanowires' electron transport properties. Here, we use thermopower and conductance measurements for transport characterization of Ga 0.95Mn 0.05As nanowires over a broad temperature range. We determine the carrier type (holes) and concentration and find a sharp increase of the thermopower below temperatures of 120 K that can be qualitatively described by a hopping conduction model. However, the unusually large thermopower suggests that additional mechanisms must be considered as well. © 2012 Phillip M. Wu et al.

  • 1692.
    Wärnestål, Pontus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Formal Learning Sequences and Progression in the Studio: A Framework for Digital Design Education2016In: Journal of Information Technology Education: Innovations in Practice, ISSN 2165-3151, E-ISSN 2165-316X, Vol. 15, no 1, p. 35-52Article in journal (Refereed)
    Abstract [en]

    This paper examines how to leverage the design studio learning environment throughout longterm Digital Design education in order to support students to progress from tactical, well-defined, device-centric routine design, to confidently design sustainable solutions for strategic, complex, problems for a wide range of devices and platforms in the digital space. We present a framework derived from literature on design, creativity, and theories on learning that: (a) implements a theory of formal learning sequences as a user-centered design process in the studio; and (b) describes design challenge progressions in the design studio environment modeled in seven dimensions. The framework can be used as a tool for designing, evaluating, and communicating course progressions within – and between series of – design studio courses. This approach is evaluated by implementing a formal learning sequence framework in a series of design studio courses that progress in an undergraduate design-oriented Informatics program. Reflections from students, teachers, and external clients indicate high student motivation and learning goal achievement, high teacher satisfaction and skill development, and high satisfaction among external clients.

  • 1693.
    Wärnestål, Pontus
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Kan man föreläsa på ett bibliotek?: Kombinerad lärande- och designmiljö på fältet2012In: NU2012: Gränslöst lärande: Göteborg 17-19 oktober 2012: konferenskatalog, 2012, p. 29-31Conference paper (Refereed)
  • 1694.
    Wärnestål, Pontus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Studio Course Progression in Digital Design Education2013Conference paper (Refereed)
    Abstract [en]

    This paper examines how to leverage the design studio learning environment throughout long-term education in order to support students to progress from tactical, well-defined, device-centric routine design, to confidently design sustainable solutions for strategic, “wicked”, and device-agnostic problems. We present a model that describes design challenge progressions in the design studio environment based on six dimensions derived from literature on design, creativity, and theories on learning. This contribution can be used as a tool for designing course progressions within – and between – series of design studio courses, and is exemplified with a four-step studio progression in a three-year undergraduate design-oriented informatics program.

  • 1695.
    Wärnestål, Pontus
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Kronlid, Fredrik
    Talkamatic AB, Gothenburg, Sweden.
    Towards a user experience design framework for adaptive spoken dialogue in automotive contexts2014In: IUI'14: 19th International Conference on Intelligent User Interfaces: Haifa, Israel – February 24-27, 2014, New York, NY: ACM Press, 2014, p. 305-310Conference paper (Refereed)
    Abstract [en]

    We present an initial set of design principles for designing efficient, effective, coherent, and desirable adaptive spoken interaction for traffic information and navigation. The principles are based on a qualitative analysis of driver interactions with an adaptive speech prototype along with driver interviews. The derived set of principles range from high-level fundamental design values, conceptual and behavioral principles, to low-level interface-level principles that can guide the design of adaptive spoken dialogue interaction in the car from a user experience perspective. © 2014 ACM.

  • 1696.
    Wärnestål, Pontus
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Lindqvist, Mats
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Course Structuring for Procedural Knowledge in Interaction Design Education2012In: IRIS 35: Proceedings of the 35th Information Systems Research Seminar in Scandinavia: Designing the Interactive Society, Uppsala: Department of Informatics and Media, Uppsala University , 2012Conference paper (Refereed)
    Abstract [en]

    Society’s use of increasingly complex information technology is, in a long-term perspective, shaped by the way we train our future designers and developers of information systems. By preparing students for practice on the field, in complex use-contexts, we aim to help student’s bridge theory and practice, thereby helping them incorporate procedural knowledge and reflective practice in their skill repertoire. This paper presents a new course structure founded on active, contextual, and peer-based formative learning. Based on student and teacher reflections from two implementations of a course in Interaction Design, we find that our approach enhances the students’ understanding, and assimilation, of the reflective aspect of interaction design practice.

  • 1697.
    Wärnestål, Pontus
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Lindqvist, Mats
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Designerly Ways of Teaching and Learning: A Course Structure for Interaction Design2013In: Journal of Learning in Higher Education, ISSN 1936-346X, Vol. 9, no 1, p. 179-188Article in journal (Refereed)
    Abstract [en]

    Society´s use of increasingly complex information technology is, in a long-term perspective, shaped by the way we train our future designers and developers of information systems. By preparing students for practice on the field, in complex use-contexts, we aim to help student’s bridge theory and practice, thereby helping them incorporate procedural knowledge and reflective practice in their skill repertoire. This paper presents a new course structure founded on active, contextual, and peer-based formative learning. Based on student and teacher reflections from two implementations of a course in Interaction Design, we find that our approach enhances the students’ understanding, and assimilation, of the reflective aspect of interaction design practice.

  • 1698.
    Wärnestål, Pontus
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Lindqvist, Mats
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Designerly Ways of Teaching and Learning: A Course Structure for Interaction Design2012In: Joint International Conferences 2012 Academic Business World International Conference & International Conference on Learning and Administration in Higher Education: Proceedings, 2012, p. 79-79Conference paper (Refereed)
  • 1699.
    Wärnestål, Pontus
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Nygren, Jens M
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Building an Experience Framework for a Digital Peer Support Service for Children Surviving from Cancer2013In: Proceedings of Interaction Design and Children (IDC'13), New York, NY: Association for Computing Machinery (ACM), 2013, p. 269-272Conference paper (Refereed)
    Abstract [en]

    Childhood cancer survivors adjust to the physical, mental, and social difficulties associated with their illness and treatment. This process can be facilitated by social support from peers. For children, this is often problematic due to geographical, clinical, and age-related limitations. This paper reports on a stakeholder assessment study that confirms the relevance of a digital peer support service for childhood cancer survivors. The analysis establishes where in the existing health care process the digital peer support service should be introduced, what actors play a key role in facilitating service onboarding and use, and characterizes desirable user experience qualities. The analysis also yields a collection of design challenges to be addressed in the development of the digital peer support service. Copyright 2013 ACM.

  • 1700.
    Wärnestål, Pontus
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Svedberg, Petra
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Lindberg, Susanne
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Man and Information technology laboratory (MI-lab).
    Nygren, Jens M.
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Effects of Using Child Personas in the Development of a Digital Peer Support Service for Childhood Cancer Survivors2017In: Journal of Medical Internet Research, ISSN 1438-8871, E-ISSN 1438-8871, Vol. 19, no 5, article id e161Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Peer support services have the potential to support children who survive cancer by handling the physical, mental, and social challenges associated with survival and return to everyday life. Involving the children themselves in the design process allows for adapting services to authentic user behaviors and goals. As there are several challenges that put critical requirements on a user-centered design process, we developed a design method based on personas adapted to the particular needs of children that promotes health and handles a sensitive design context.

    OBJECTIVE: The purpose of this study was to evaluate the effects of using child personas in the development of a digital peer support service for childhood cancer survivors.

    METHODS: The user group's needs and behaviors were characterized based on cohort data and literature, focus group interviews with childhood cancer survivors (n=15, 8-12 years), stakeholder interviews with health care professionals and parents (n=13), user interviews, and observations. Data were interpreted and explained together with childhood cancer survivors (n=5) in three explorative design workshops and a validation workshop with children (n=7).

    RESULTS: We present findings and insights on how to codesign child personas in the context of developing digital peer support services with childhood cancer survivors. The work resulted in three primary personas that model the behaviors, attitudes, and goals of three user archetypes tailored for developing health-promoting services in this particular use context. Additionally, we also report on the effects of using these personas in the design of a digital peer support service called Give Me a Break.

    CONCLUSIONS: By applying our progressive steps of data collection and analysis, we arrive at authentic child-personas that were successfully used to design and develop health-promoting services for children in vulnerable life stages. The child-personas serve as effective collaboration and communication aids for both internal and external purposes.

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