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  • 101.
    Fard, Ali
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Johnson, Tord
    Mälardalen University, Department of Computer Science and Electronics.
    Lindner, Martin
    Mälardalen University, Department of Computer Science and Electronics.
    Åberg, Denny
    Mälardalen University, Department of Computer Science and Electronics.
    A Comparative Study of CMOS LC VCO Topologies for Wide-Band Multi-Standard Transceivers2004In: Midwest Symposium on Circuits and SystemsVolume 3, 2004, 2004, p. 17-20Conference paper (Other academic)
  • 102.
    Fard, Ali
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Johnson, Tord
    Mälardalen University, Department of Computer Science and Electronics.
    Åberg, Denny
    Mälardalen University, Department of Computer Science and Electronics.
    Design of a Dual-Band 5/2.5 GHz CMOS VCO for 802.11 a/b/g WLAN Radios2004In: Proceedings of Swedish System-on-Chip Conference (SSOC), 2004Chapter in book (Other academic)
  • 103.
    Fard, Ali
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Johnson, Tord
    Mälardalen University, Department of Computer Science and Electronics.
    Åberg, Denny
    Mälardalen University, Department of Computer Science and Electronics.
    Design of a dual-band 5/2.4 GHZ CMOS VCO for 802.11 A/B/G WLAN transceivers2004In: IEEE Asia-Pacific Conference on Circuits and Systems, Proceedings, APCCAS, Volume 1, 2004, 2004, p. 429-432Conference paper (Other academic)
    Abstract [en]

    A dual-band CMOS VCO with a divide-by-two circuit, operating between 4.7-6.2/2.35-3.1 GHz is demonstrated in a 0.35mum process. The VCO phase noise is reduced by matching the transconductance and impedance of the active devices. By using a divide-by-two stage quadrature signals for the 802.11 b/g standards are obtained. The VCO is optimized for low phase noise and small amplitude variations across the tuning range. The phase noise levels are less than -116.5 and -126 dBc/Hz at 1 MHz offset in the upper and lower frequency band respectively.

  • 104.
    Fard, Ali
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Jonsson, Tord
    Mälardalen University, Department of Computer Science and Electronics.
    Åberg, Denny
    Mälardalen University, Department of Computer Science and Electronics.
    A Low Power Wide-Band CMOS VCO for Multi-Standard Radios2004In: Proceedings - 2004 IEEE Radio and Wireless Conference, RAWCON, 2004, p. 79-82Conference paper (Other academic)
    Abstract [en]

    This paper presents a single monolithic wide band VCO for multi-standard radios. Analysis on a differential switched capacitor circuit is performed. Its impact on phase noise and power dissipation is especially addressed. The analysis is demonstrated and verified in a fully integrated CMOS VCO that consumes 2.7 mA from a 1.8 V supply and operates with a wide frequency band from 3.5 - 5.3 GHz. The measured phase noise is less than -110 dBc/Hz at 1 MHz offset within the entire tuning range.

  • 105.
    Fard, Ali
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Åberg, Denny
    Mälardalen University, Department of Computer Science and Electronics.
    A novel 18 GHz 1.3 mW CMOS frequency divider with high input sensitivity2005In: ISSCS 2005: International Symposium on Signals, Circuits and Systems - Proceedings, 2005, p. 409-412Conference paper (Other academic)
    Abstract [en]

    A novel CMOS high speed divide-by-two circuit with very low power consumption is proposed in this paper. The circuit features very low input capacitance and a wide locking range of 1.5-18 GHz with a power consumption of less than 13 mW at 1.8 V. The input sensitivity of the stage is improved significantly when compared to conventional dynamic loaded high frequency dividers. The concept and design issue of the circuit is presented together with a performance comparison to existing topologies. The idea is demonstrated and verified in a standard 0.18 μm CMOS process through realistic simulations originating from a complete layout using moderately extracted parasitics.

  • 106.
    Fard, Ali
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Åberg, Denny
    Mälardalen University, Department of Computer Science and Electronics.
    A Reconfigurable CMOS VCO with and Automatic Amplitude Controller for Multi-Band RF Front-Ends2005In: Proceedings of the 2005 European Conference on Circuit Theory and Design, 2005, p. 95-98Conference paper (Other academic)
    Abstract [en]

    A fully integrated reconfigurable 3.6-6.0 GHz 0.18μm CMOS VCO with an automatic amplitude controller (AAC) for multi-standard front-ends is proposed. Due to the wide tuning range, utilizing mixed tuning technique, large amplitude variations over the band are observed. Thus a novel low noise AAC is implemented to stabilize the amplitude regardless of operation frequency. Measurements are performed both with and without the AAC loop active, showing that the AAC loops noise contributions are very small. The circuit displays phase noise levels of-124 dBc/Hz or less at 3 MHz offset within the entire frequency band while consuming 7.7-12.2 mW of power. The relative amplitude variation over the frequency band are 100 mV.

  • 107.
    Fersman, Elena
    et al.
    Uppsala University, Sweden.
    Krcal, Pavel
    Uppsala University, Sweden.
    Pettersson, Paul
    Mälardalen University, Department of Computer Science and Electronics. Uppsala University, Sweden.
    Yi, Wang
    Uppsala University, Sweden.
    Task Automata: Schedulability, Decidability and Undecidability2007In: International Journal of Information and Computation, ISSN 0890-5401, Vol. 205, p. 1149-1172Article in journal (Refereed)
    Abstract [en]

    We present a model, task automata, for real time systems with non-uniformly recurring computation tasks. It is an extended version of timed automata with asynchronous processes that are computation tasks generated (or triggered) by timed events. Compared with classical task models for real time systems, task automata may be used to describe tasks (1) that are generated non-deterministically according to timing constraints in timed automata, (2) that may have interval execution times representing the best case and the worst case execution times, and (3) whose completion times may influence the releases of task instances. We generalize the classical notion of schedulability to task automata. A task automaton is schedulable if there exists a scheduling strategy such that all possible sequences of events generated by the automaton are schedulable in the sense that all associated tasks can be computed within their deadlines. Our first technical result is that the schedulability for a given scheduling strategy can be checked algorithmically for the class of task automata when the best case and the worst case execution times of tasks are equal. The proof is based on a decidable class of suspension automata: timed automata with bounded subtraction in which clocks may be updated by subtractions within a bounded zone. We shall also study the borderline between decidable and undecidable cases. Our second technical result shows that the schedulability checking problem will be undecidable if the following three conditions hold: (1) the execution times of tasks are intervals, (2) the precise finishing time of a task instance may influence new task releases, and (3) a task is allowed to preempt another running task.

  • 108.
    Fohler, Gerhard
    Mälardalen University, Department of Computer Science and Electronics.
    Flexibility in Statically Scheduled Real-Time Systems1994Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Static scheduling has been shown to be appropriate for a variety of hard real-time systems, mainly due to the verifiable timing behavior of the system and the complex task models supported.

    Its application is, however, impeded in systems with changing operational modes and critical activities, that arrive infrequently with unknown occurrence times. This thesis presents an approach to overcome these shortcomings. It addresses static scheduling, illustrated by an algorithm serving as case study, and provides concepts to extend the scope of statically scheduled systems to deal with mode changes properly and to provide for efficient handling of dynamic activities.

    Mode changes are performed by switching from one periodically executing static schedule to another via a special schedule to prepare for the change. As all involved schedules are constructed statically, all actions executing the mode change do so deterministically: Given the current mode, time, and mode change request, the exact executions during the mode change and their completion time are known before run-time.

    Dynamic activities are incorporated into static schedules by making use of the unused resources and leeways in the schedule. We present mechanisms to effectively maintain information about the amount of dynamic activity that can be accommodated without impairing the feasible execution of statically scheduled tasks. Ontop of this service, aperiodic tasks can be handled in a very simple way. We furthermore present an on-line guarantee algorithm.

    A combined approach integrates both methods.

  • 109.
    Folke, Mia
    Mälardalen University, Department of Computer Science and Electronics.
    A system for optimizing an athletes performance2006Conference paper (Refereed)
  • 110.
    Folke, Mia
    Mälardalen University, Department of Computer Science and Electronics.
    Estimate the Individual Anaerobic Threshold by measuring End-tidal carbon dioxideIn: International Journal of Sports Medicine, ISSN 0172-4622, E-ISSN 1439-3964Article in journal (Refereed)
  • 111.
    Folke, Mia
    Mälardalen University, Department of Computer Science and Electronics.
    Ett system som optimerar prestationsförmågan hos en idrottare2007Conference paper (Refereed)
  • 112.
    Folke, Mia
    Mälardalen University, Department of Computer Science and Electronics.
    Measurements of Respiratory Carbon Dioxide2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [sv]

    Koldioxid är en central parameter för metabolismen i alla levande varelser. Hos människan regleras koldioxidhalten främst genom andningen. Därför är det viktigt att kunna mäta och övervaka koldioxidhalten i fysiologiska applikationer så väl inom sportmedicin som inom vården, till exempel på intensivvårdsavdelningar. Dessa mätningar kräver adekvat mätutrustning.

    Syftet med denna avhandling är att kritiskt granska föreslagna metoder för övervakning av andningsaktiviteten, att föreslå och utveckla förbättringar, samt att föreslå och utveckla nya applikationer för mätning av koldioxidhalten i utandningsluften med hjälp av en elektroakustisk sensor.

    Mätning av koldioxid i utandningsluften har den fördelen över andra föreslagna metoder för andningsövervakning att den även ger information om förhållandet i arteriellt blod då partialtrycket för koldioxid i slutet av ett andetag är lika stort som i artärblod hos lungfriska personer.

    Den föreslagna tekniken bygger på en elektroakustisk sensor som kan registrera och mäta koldioxidhalten i utandningsluften om fukt- och temperaturvariationer utjämnas med hjälp av filter. Den elektroakustiska sensorn består av en ultraljudssändare och en reflektor placerade i varsin ände av ett perforerat rör. Den elektriska impedansen i sensorn representerar molekylvikten inne i sensorkaviteten. Molekylmassan har ett linjärt förhållande till koldioxidhalten så länge övriga gaser hålls konstanta.

    Det faktum att partialtrycket av koldioxid i slutet av ett andetag kan mätas med den elektroakustiska sensorn gör den användbar i flera kliniska situationer om andra gaser inte kan påverka mätningarna.

    Partialtrycket av koldioxid i slutet av ett andetag har visat sig vara användbar som en indikator för mjölksyratröskeln då personens individuella mjölksyratröskel infaller då partialtrycket av koldioxid i slutet av ett andetag börjar minska. Det ger en ny applikation inom sportmedicin. På det sättet är det möjligt för en idrottare att mäta variationerna i sin mjölksyratröskel, i sin egen sport på daglig basis, vilket kan användas för att optimera arbetsintensiteten under träning och tävling. Trots att det elektroakustiska sensorsystemet inte är selektivt för koldioxid och därför påverkas även av förändringar i syre i utandningsluften har det visat sig fungera i denna applikation.

  • 113.
    Folke, Mia
    Mälardalen University, Department of Computer Science and Electronics.
    Utveckling av ett system för identifiering av laktattröskeln2007Conference paper (Refereed)
  • 114.
    Folke, Mia
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Cererud, L.
    Ekström, M.
    Hök, Bertil
    Critical review of non-invasive respiratory monitoring in medical care2003In: Medical & Biological Engineering & Computing, Vol. 41, no 4, p. 377-383Article in journal (Refereed)
    Abstract [en]

    Respiratory failure can be difficult to predict. It can develop into a life-threatening condition in just a few minutes, or it can build up more slowly. Thus continuous monitoring of respiratory activity should be mandatory in clinical, high-risk situations, and appropriate monitoring equipment could be life-saving. The review considers non-invasive methods and devices claimed to provide information about respiratory rate or depth, or gas exchange. Methods are categorised into those responding to movement, volume and tissue composition detection; air flow, and blood gas concentration. The merits and limitations of the methods and devices are analysed, considering information. content and their ability to minimise the rate of false alarms and false non-alarms. It is concluded that the field of non-invasive respiratory monitoring is still in an exploratory phase, with numerous reports on specific device solutions but less work on evaluation and adaptation to clinical requirements. Convincing evidence of the clinical usefulness of respiratory monitors is still lacking. Devices responding only to respiratory rate, and lacking information about actual gas exchange, will have limited clinical value. Furthermore, enhancement in specificity and sensitivity to avoid false alarms and non-alarms will be necessary to meet clinical requirements. Miniature CO2 sensors are identified as one route towards substantial improvement.

  • 115.
    Folke, Mia
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Granstedt, Fredrik
    Hök, Bertil
    Hök Instrument AB, Västerås, Sweden .
    Scheer, Håkan
    Västerås Central Hospital, Sweden.
    Comparative Provocation Test of Respiratory Monitoring Methods2002In: Journal of Clinical Monitoring and Computing, ISSN 1387-1307, Vol. 17, no 2, p. 97-103Article in journal (Refereed)
    Abstract [en]

    Objective. The aim of this study was to compare clinically relevant performance of: 1) a prototype respiratory sensor based on capnometry with two alternative signal receptor fixations, 2) a fiberoptic humidity sensor and 3) human visual observation. Comparative provocation tests were performed on volunteers at the Post-Anesthesia Care Unit at Västerås Central Hospital. Methods. The experimental tests involved 10 healthy, voluntary test subjects, instructed to intersperse normal breathing with protocol provocations of breath holding, limb and head movements, and nasal oxygen supplement. The signal outputs from the three respiratory monitoring methods were recorded on a personal computer. The signal analysis included visual categorising of the signals and counting breath events. Recognising that none of the methods could act as reference, events were classified as "unanimous," "majority" or "minority" events depending on how many of the three methods that detected a breath. Results. The average total recording time was 37 minutes per subject. The respiratory rates varied from 6.5 to 19 breaths per minute, with a mean value of 11.4 breaths/minute. The breath hold duration ranged from 18 to 50 seconds. Discrepancies between the three methods were found in more than 20% of the marked events. The most frequent majority events were due to events not recorded by the observer who, on the other hand, contributed the least to minority events. The provocations made by the subjects during the measurement did not increase the rates of majority and minority events, compared to periods of no provocation. The fiberoptic device exhibited a large count of minority events but a smaller contribution to majority events than the capnometry prototype. Conclusions. The capnometry and fiberoptic sensors exhibit differences in responses that may be understood from basic principles. The importance of the physical application of the sensor to the patient was clearly observed. The optimum design remains to be found.

  • 116.
    Folke, Mia
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Gullstrand, L.
    Hök, Bertil
    A pilot study to estimate the lactate threshold using an electro acoustic sensor2005Conference paper (Other academic)
  • 117.
    Folke, Mia
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Hök, Bertil
    Hök Instrument AB, Västerås, Sweden .
    Ekström, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Bäcklund, Ylva
    Mälardalen University, Department of Computer Science and Electronics.
    End tidal carbon dioxide measurement using an electro acoustic sensor2004In: Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2004, p. 3452-3455Conference paper (Other academic)
    Abstract [en]

    End tidal carbon dioxide measurement with an electro-acoustic sensor is demonstrated. The sensor consists of an acoustic resonator coupled to a low cost electro-acoustic element. By simultaneous measurements with a reference sensor, the new device was tested on subjects performing exercise, hypo- and hyperventilation whereby the CO2 concentration ranged from 2.1 to 7.0 kPa. The output from the experimental device correlated well with the reference CO2 readings with a correlation coefficient of 0.976. Response time for expiration less than 0.8 seconds was noted. The new device could be useful in situations where selectivity to other gases is not important.

  • 118.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Accurate predictions of real-time properties for components2006Conference paper (Refereed)
  • 119.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Increasing Accuracy of Property Predictions for Embedded Real-Time Components2006Conference paper (Refereed)
    Abstract [en]

    Many embedded systems for vehicles and consumer electronics critically depend on efficient, reliable control software, and practical methods for their production. Component-based software engineering for embedded systems is currently gaining ground since variability, reusability, and maintainability are supported. However, existing tools and methods do not guarantee efficient resource usage in these systems. We present methods that increases the accuracy in extra-functional property predictions, by considering context without restricting reusability; thus, enabling less pessimistic extra-functional component properties and, hence, improving resource utilisation.

  • 120.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Transformation of component models to real-time models2005Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    Industry is constantly looking for new developments in software for use in increasingly complex computer applications. Today, the development of component-based systems is an attractive area for both Industry and Academia. The systems we focus on in this thesis are embedded computers, in particular those in automotive systems. A modern car incorporates several embedded computers that control different functions of the car, e.g., anti-spin and anti-lock breaks. The main purpose of this thesis is to investigate how component technologies for use in embedded systems can reduce resource usage without compromising non-functional requirements, such as timeliness. The component-technologies available have not yet been used extensively in the vehicular domain. To understand why this is the case we have conducted a survey and performed evaluations of the requirements of the vehicular industry with respect to software and software development. The purpose of the evaluation was to provide a foundation for defining models, methods and tools for component-based software engineering. The main contribution of this work is the implementation and evaluation of a framework for resource-efficient mappings between component-models and real-time systems. Few component technologies today consider the mapping between components and run-time tasks. We show how effective mappings can reduce memory usage and CPU-overhead. The implemented framework utilizes genetic algorithms to find feasible, resource efficient mappings. We show how component-models designed for resource constrained safety-critical embedded real-time systems can use powerful compile-time techniques to realize the component-based approach and ensure predictable behaviour. Further, we propose a resource reclaiming strategy for component-based real-time systems, to decrease the impact of pessimistic execution time predictions. In our approach, components run in different quality levels as unused processor time is accumulated.

  • 121.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Land, Rikard
    Mälardalen University, Department of Computer Science and Electronics.
    Packaging Component-Analysis for Reuse2007Conference paper (Refereed)
    Abstract [en]

    Component-Based Software Engineering (CBSE) promises an improved ability to reuse software which would potentially decrease the development time while also improving the quality of the system, since the components are (re-)used by many. However, CBSE has not been as successful in the embedded systems domain as in the desktop domain, partly because requirements on embedded systems are stricter (e.g. requirements on safety, real-time and minimizing hardware resources). Moreover these requirements differ between industrial domains. Paradoxically, components should be context-unaware to be reusable at the same time as they should be context sensitive in order to be predictable and resource efficient. This seems to be a fundamental problem to overcome before the CBSE paradigm will be successful also in the embedded systems domain. Another problem is that some of the stricter requirements for embedded systems require certain analyses to be made, which may be very complicated and time-consuming for the system developer.

    This paper describes how one particular kind of analysis, of worst-case execution time, would fit into the CBSE development processes so that the component developer performs some analyses and presents the results in a form that is easily used for component and system verification during system development. This process model is not restricted to worst-case execution time analysis, but we believe other types of analyses could be performed in a similar way.

  • 122.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics. CC Systems, Västerås, Sweden.
    Land, Rikard
    Mälardalen University, Department of Computer Science and Electronics.
    Reusable Component Analysis for Component-Based Embedded Real-Time Systems2007In: Proceedings of the International Conference on Information Technology Interfaces, ITI, 2007, 2007, p. 615-620Conference paper (Refereed)
    Abstract [en]

    Component-Based Software Engineering (CBSE) promises an improved ability to reuse software which would potentially decrease the development time while also improving the quality of the system, since the components are (re-)used by many. However, CBSE has not been as successful in the embedded systems domain as in the desktop domain, partly because requirements on embedded systems are stricter (e.g. requirements on safety, real-time and minimizing hardware resources). Moreover these requirements differ between industrial domains. Paradoxically, components should be context-unaware to be reusable at the same time as they should be context sensitive in order to be predictable and resource efficient. This seems to be a fundamental problem to overcome before the CBSE paradigm will be successful also in the embedded systems domain. Another problem is that some of the stricter requirements for embedded systems require certain analyses to be made, which may be very complicated and time-consuming for the system developer.

    This paper describes how one particular kind of analysis, of worst-case execution time, would fit into the CBSE development processes so that the component developer performs some analyses and presents the results in a form that is easily used for component and system verification during system development. This process model is not restricted to worst-case execution time analysis, but we believe other types of analyses could be performed in a similar way.

  • 123.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Ermedahl, Andreas
    Mälardalen University, Department of Computer Science and Electronics.
    Nolin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Clustering Worst-Case Execution Times for Software Components2007In: Proceedings of the 7th International Workshop on Worst Case Execution Time Analysis (WCET'07), Pisa, Italy, 2007, p. 19-25Conference paper (Refereed)
    Abstract [en]

    For component-based systems, classical techniques for WCET-estimation produce unacceptable overestimations of the WCET. This is because software components have more general behavior in order to support reuse. Existing tools and methods for component-based software engineering (CBSE) do not yet adequately consider reusable analyses.

    We present a method that allows different WCETs to be associated with subsets of the component behavior by clustering WCETs with respect to behavior. The method is intended to be used for facilitating reusable WCET analysis for reusable software components. We illustrate our technique and demonstrate its potential in achieving tight WCET-estimates for components with rich behavior.

  • 124.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Ermedahl, Andreas
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Contract-Based Reusable Analysis for Software Components with Extra-Functional Properties2007In: Proceedings of the Work-In-Progress (WIP) session of the 19th Euromicro Conference on Real-Time Systems (ECRTS'07), Pisa, Italy, 2007, p. 57-60Conference paper (Refereed)
    Abstract [en]

    Component-based software engineering (CBSE) for embedded systems is currently gaining ground because of shortened time-to-market, reduced development costs and increased software quality. One main characteristic of CBSE that enable these benefits is its facilitation of component reuse. However, existing tools and methods do not consider reuse of extra-functional properties in these systems.

    In this paper we extend our previous work on contract-based reusable execution time predictions for software components with additional extra-functional properties, such as memory and energy consumption.

  • 125.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Ermedahl, Andreas
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Worst-Case Execution Time Clustering for Software Components2007Report (Other academic)
    Abstract [en]

    For component-based systems, classical techniques for WCET-estimation produce unacceptable overestimations of the WCET. This is because software components have more general behavior in order to support reuse. Existing tools and methods for component-based software engineering (CBSE) do not yet adequately consider reusable analyses. We present a method that allows different WCETs to be associated with subsets of the component behavior by clustering WCETs with respect to behavior. The method is intended to be used for facilitating reusable WCET analysis for reusable software components. We illustrate our technique and demonstrate its potential in achieving tight WCET-estimates for components with rich behavior.

  • 126.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Schmidt, Heinz
    Mälardalen University, Department of Computer Science and Electronics.
    Contract-Based Reusable Worst-Case Execution Time Estimate2007In: Proceedings of the 13th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA'07),, 2007, p. 39-46Conference paper (Refereed)
    Abstract [en]

    We present a contract-based technique to achieve reuse of known worst-case execution times (WCET) in conjunction with reuse of software components. For resource constrained systems, or systems where high degree of predictability is needed, classical techniques for WCET-estimation will result in unacceptable overestimation of the execution-time of reusable software components with rich behavior. Our technique allows different WCETs to be associated with subsets of the component behavior. The appropriate WCET for any usage context of the component is selected be means of component contracts over the input domain. In a case-study we illustrate our technique and demonstrate its potential in achieving tight WCET-estimates for reusable components with rich behavior.

  • 127.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Schmidt, Heinz
    Mälardalen University, Department of Computer Science and Electronics.
    Predicting Execution-Time for Variable Behaviour Embedded Real-Time Components2006In: Workshop on Models and Analysis for Automotive Systems (WMAAS'06) in conjunction with the 27th IEEE Real-Time Systems Symposium (RTSS'06), Rio de Janeiro, Brazil, 2006Conference paper (Refereed)
  • 128.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Schmidt, Heinz
    Mälardalen University, Department of Computer Science and Electronics.
    Reusing Worst-Case Execution Time Analysis with Component Contracts2007In: Proceedings of the 9th Real-Time in Sweden (RTiS'07), 2007Conference paper (Refereed)
    Abstract [en]

    We present a contract-based technique to achieve reuse of known worst-case execution times (WCET) in conjunction with reuse of software components. For resource constrained systems, or systems where high degree of predictability is needed, classical techniques for WCET-estimation will result in unacceptable overestimation of the execution-time of reusable software components with rich behavior. Our technique allows different WCETs to be associated with subsets of the component behavior. The appropriate WCET for any usage context of the component is selected be means of component contracts over the input domain. In a case-study we illustrate our technique and demonstrate its potential in achieving tight WCET-estimates for reusable components with rich behavior.

  • 129.
    Fröberg, Joakim
    Mälardalen University, Department of Computer Science and Electronics.
    Engineering Automotive Electronic Systems: Decision Support for Successful Integration2007Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The electronic system of a modern vehicle is essential to achieve a successful automotive product. Vehicle development is performed by integrating components that include embedded electronics from several suppliers.

    This thesis present results on the subject of integration of automotive electronic systems. Our studies aim at providing knowledge on how to integrate automotive electronic systems successfully in a setting where vehicles are developed based on existing platforms. We focus on early phases of automotive electronic system development and in particular on the decisions taken in integration of electronic sub-systems. The contribution is the presented support for making decisions to successfully integrate electronic systems for modern vehicles. The contribution includes an overview of driving factors of automotive electronics system design, a validated set of success practices for the integration of electronic components, and the proposal and demonstration of a decision model. The influential factors and the validated set of practices stems from case studies of products and projects while the proposed decision model is a result of combining two general models for architecture analysis and decision making, ATAM and AHP.

    We demonstrate that choices in strategy and design preceding integration are central to achieve a successful integration. Our studies show that problems arise from omitted strategy decisions and we provide a checklist for decision making in the areas; functionality, platform, integration design, and assigning responsibilities. We provide a recommendation that we validate in a multiple cases study where fulfillment of recommendations is demonstrated to affect project success in integration projects.

    The potential gain for OEMs using our results lies in achieving more solid foundations for design decisions. Designers and managers could potentially find central decisions on integration strategy early that, if omitted, could cause delays. Thus, applying the result could avoid pitfalls and enable successful integration projects.

  • 130.
    Fröberg, Joakim
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Sandström, Kristian
    Norström, Christer
    Business Situation Reflected in Automotive Electronic Architectures: Analysis of Four Commercial CasesManuscript (Other academic)
  • 131.
    Fröberg, Joakim
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Wallin, Peter
    Mälardalen University, Department of Computer Science and Electronics.
    Axelsson, Jakob
    Mälardalen University, Department of Computer Science and Electronics.
    Towards Quality Assessment in Integration of Automotive Software and Electronics: An ATAM approach2006In: Proceedings of the 6th Conference on Software Engineering and Practice in Sweden, Umeå University, Umeå, Sweden, 2006Conference paper (Refereed)
    Abstract [en]

    In this paper we perform a pilot study of evaluation of integration strategies in an automotive electronics system context. We describe the problem of choosing integration strategy and we outline the use of the Architecture Tradeoff and Analysis Method, ATAM, for evaluating integration strategies.

    We exemplify the use of the ATAM by evaluating the integration decisions concerning the physical connection of a theoretic example system; a computer controlled automatic gearbox. A utility tree describing the most important qualities of the product is elicited by interviews with system architects and product specialists at Volvo Construction Equipment. We show how an evaluation score card can be used to aid in integration decisions.

    Also, perform preliminary analysis and provide some discussion points from the result. This early analysis shows that ATAM has weaknesses in that it is sensitive to errors in the elicitation process and that the weighting of the resulting scenarios can be coarse grained. One strength of the ATAM is that design decisions and quality goals become visible to many stakeholders. Our proposed use of ATAM does not include any cost or effort estimates, but only relative quality estimates.

    In our pilot study example we find that the integration of a software component as opposed to integration of a whole ECU, ranks higher with respect to the desired qualities.

  • 132.
    Fröberg, Joakim
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Åkerholm, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Integration of Electronic Components in Heavy Vehicles: A Study of Integration in Three Cases2006In: Proceedings from Systems Engineering/Test and Evaluation Conference, Melbourne, 25-27 September 2006, Melbourne, 2006Conference paper (Refereed)
    Abstract [en]

    Complexity of in-vehicle computer systems and the availability of computerized mechatronics yield a situation where automotive electronic systems are designed by integration. Since the qualities of a modern vehicle are much dependent on the in-vehicle computer system, integration is a major issue which has proved difficult with respect to assessing quality and cost. OEMs of automotive products want leverage over targeted qualities and the cost of scale when purchasing supplier components.

    In this paper, we present three cases of integration of mechatronic components into vehicle platforms of Volvo Construction Equipment and focus on the integration of embedded computer systems. The study shows problems areas of communicating architecture constraints, evaluation of components in early phases of development, and lacking definitions of responsibilities.

    Based on the study, we list four recommended practices to avoid the problems found in the cases. The analysis shows that integration of embedded computers should be considered early in development and in order to reduce project risks, the early assessment of computers need be fairly detailed. From the study we also present driving requirements in design of in-vehicle computer systems.

  • 133.
    Fröberg, Joakim
    et al.
    Volvo Construction Equipment, Eskilstuna, Sweden.
    Åkerholm, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Sandström, Kristian
    Mälardalen University, Department of Computer Science and Electronics.
    Norström, Christer
    Mälardalen University, Department of Computer Science and Electronics.
    Key Factors for Achieving Project Success in Integration of Automotive Mechatronics2007In: Journal of Innovations in Systems and Software Engineering, ISSN 1614-5046, Vol. 3, no 2, p. 141-155Article in journal (Refereed)
    Abstract [en]

    In this paper, we present a multiple case study on integration of automotive mechatronic components. Based on the findings, we identify that the root causes of problems in integration are largely related to decisions omitted in electronic strategy.

    We present and recommend use of checklists defining key factors to address in order to achieve successful integration projects in terms of cost and quality. Our recommendations are defined by checklists for critical decisions in areas; functionality, platform, integration, and stakeholder involvement.

    The recommendations are established based on practitioner experience and then validated in a multiple case study. Five cases of integration are studied for different heavy vehicles in one company, and the fulfillment of our recommendations is measured. Finally we define project success criteria and we compare the level of fulfillment with the project success in terms of time plan and resource consumption.

    The main contribution of this study is the validated recommendations, each including a set of checkpoints that defines recommendation fulfillment. We also present defining characteristics to identify a high risk project. We provide a set of observable project properties and show how they affect project risk.

  • 134.
    Funk, Peter
    Mälardalen University, Department of Computer Science and Electronics.
    Second Generation Intelligen Sensor Systems2006Conference paper (Refereed)
    Abstract [en]

    There is an increased market demand of "smart" sensor systems, both from system and product developers as well as end users. The first generation intelligent sensor systems are sensors with some limited processing capacity that may be used for processing or compressing data, or sending data, calculating average etc. Our proposed definition of the second generation intelligent sensors are that they are capable of behaviour, that a human would classify as intelligent if seen in s sensor. This functionality may be integrated into the hardware, or in the sensors control program. <br><br>

    Example of such functionality may be to identify if the sensor is fully functional and self-calibrating properties. The sensor may also send confidence estimation on how confident it is in the current sensor readings. The sensor may also learn to recognise different internal and external disturbances, e.g. learn how the signal of a close mobile phone influences the sensor readings and correct the readings. Some sensors may also have delegated responsibilities, e.g. turn some sensitive equipment of if they detect some serious conditions needing immediate action, and where a human or centralized response would not be able to arrive in time. This could be to lower the clock speed to avoid overheating. <br><br>

    If sensors are equipped with communication capabilities then an intelligent sensor could be classified as an agent. Wooldridge and Jennings (1995) defines agents to be computer systems (hardware and software, able to observe its environment and influence its environment) that have properties such as: <br>

    • autonomy<br>

    • social abilities<br>

    • reactivity and pro-activeness<br>

    This does not necessarily mean that they have to be designed and implemented with different methods than today. Methods and techniques from artificial intelligent (AI), such as agents or learning systems are today implemented with main steam methods and techniques. The difference is what the requirements are and it is a different way of thinking, often opening a door to new solutions, not always thought of when taking an incremental approach to improvement and extended functionality. <br>

    Suggested important properties in an agent based approach to sensors are: <br>

    1. flexibility and decentralised decision making. <br>

    2. localized learning and experience reuse. <br>

    3. learning and experience sharing between agents with similar tasks. <br>

    4. ability to collaborate with other agents or even humans<br>

    This functionality could be implemented both in hardware or software. An interesting question is how a sensor handles feedback, both positive and negative. Other interesting opportunities arise when sensors communicate, e.g. sensors may have limited knowledge on their functionality and relation. This enables an intelligent sensor to verify its own functionality by comparing its own readings with other sensor readings. Also learning optimal intervals for cleaning or recalibrations may be such an option. If these sensors are part of a complex centrally controlled process, the process may preserve some basic behaviour if the central control process is experiencing some dysfunctions. <br><br>

    Methods and techniques from artificial intelligence area already widely used in many areas but also offer interesting and potential valuable benefits also to areas not traditionally thought of when speaking of AI, e.g. microsystems.

  • 135.
    Funk, Peter
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Olsson, Erik
    Mälardalen University, Department of Computer Science and Electronics.
    Bengtsson, Marcus
    Mälardalen University, Department of Computer Science and Electronics.
    Xiong, Ning
    Mälardalen University, Department of Computer Science and Electronics.
    Case-Based Experience Reuse and Agents for Efficient Health Monitoring, Prevention and Corrective Actions2006In: Proceedings of the 19th International Congress on Condition, COMADEM 2006, Luleå, Sweden, 2006, p. 445-453Conference paper (Refereed)
    Abstract [en]

    Experienced staffs acquire their experience during many years of practice, and sometimes also through expensive mistakes. This knowledge is often lost when technicians retire, or if companies need to downsize during periods of reduced sale. When scaling up production, new staff requires training and may repeat similar mistakes. Another issue that may be costly is when monitoring systems repeatedly give false alarms, causing expensive loss of production capacity and resulting in technicians losing trust in the systems and in worst case, switch them off. If monitoring systems could learn from previous experience for both correct and false alarms, the reliability and trust in the monitoring systems would increase. Moreover, connecting alarms to either equipment taking automatic actions or recommend actions based on the current situations and previous experience would be valuable.

    An engineer repeating the same task a second time is often able to perform the task in 1/3 of the time it took at the first time. Most corrective and preventive actions for a particular machine type have been carried out before. This past experience holds a large potential for time savings, predictability and reduced risk if an efficient experience transfer can be accomplished. But building large complex support system is not always the ideal way. We propose instead localized intelligent agents, able to either autonomously perform the necessary actions or aid a human in the decision making process by providing the necessary information needed to make an informed and validated decision.

  • 136.
    Funk, Peter
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Xiong, Ning
    Mälardalen University, Department of Computer Science and Electronics.
    Case Based Reasoning and Knowledge Discovery in Medical Applications with Time Series2006In: Computational intelligence, ISSN 0824-7935, E-ISSN 1467-8640, Vol. 22, no 3/4, p. 238-253Article in journal (Refereed)
    Abstract [en]

    This paper discusses the role and integration of knowledge discovery (KD) in case-based reasoning (CBR) systems. The general view is that KD is complementary to the task of knowledge retaining and it can be treated as a separate process outside the traditional CBR cycle. Unlike knowledge retaining that is mostly related to case-specific experience, KD aims at the elicitation of new knowledge that is more general and valuable for improving the different CBR substeps. KD for CBR is exemplified by a real application scenario in medicine in which time series of patterns are to be analyzed and classified. As single pattern cannot convey sufficient information in the application, sequences of patterns are more adequate. Hence it is advantageous if sequences of patterns and their co-occurrence with categories can be discovered. Evaluation with cases containing series classified into a number of categories and injected with indicator sequences shows that the approach is able to identify these key sequences. In a clinical application and a case library that is representative of the real world, these key sequences would improve the classification ability and may spawn clinical research to explain the co-occurrence between certain sequences and classes.

  • 137.
    Funk, Peter
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Xiong, Ning
    Mälardalen University, Department of Computer Science and Electronics.
    Discovering Key Sequences in Time Series Data for Pattern Classification2006In: Advances in Data Mining. Applications in Medicine, Web Mining, Marketing, Image and Signal Mining: 6th Industrial Conference on Data Mining, ICDM 2006, Leipzig, Germany, July 14-15, 2006. Proceedings, 2006, p. 492-505Conference paper (Refereed)
    Abstract [en]

    This paper addresses the issue of discovering key sequences from time series data for pattern classification. The aim is to find from a symbolic database all sequences that are both indicative and non-redundant. A sequence as such is called a key sequence in the paper. In order to solve this problem we first we establish criteria to evaluate sequences in terms of the measures of evaluation base and discriminating power. The main idea is to accept those sequences appearing frequently and possessing high co-occurrences with consequents as indicative ones. Then a sequence search algorithm is proposed to locate indicative sequences in the search space. Nodes encountered during the search procedure are handled appropriately to enable completeness of the search results while removing redundancy. We also show that the key sequences identified can later be utilized as strong evidences in probabilistic reasoning to determine to which class a new time series most probably belongs.

  • 138.
    Funk, Peter
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Xiong, Ning
    Mälardalen University, Department of Computer Science and Electronics.
    Discovering Knowledge about Key Sequences for Indexing Time Series Cases2006In: Advances in Case-Based Reasoning: 8th European Conference, ECCBR 2006 Fethiye, Turkey, September 4-7, 2006 Proceedings, 2006, p. 474-488Conference paper (Refereed)
    Abstract [en]

    Coping with time series cases is becoming an important issue in case based reasoning. This paper develops a knowledge discovery approach to discovering significant sequences for depicting symbolic time series cases. The input is a case library containing time series cases consisting of consecutive discrete patterns. The proposed approach is able to find from the given case library all qualified sequences that are non-redundant and indicative. A sequence as such is termed as a key sequence. It is shown that the key sequences discovered are highly usable in case characterization to capture important properties while ignoring random trivialities. The main idea is to transform an original (lengthy) time series into a more concise representation in terms of the detected occurrences of key sequences. Three alternate ways to develop case indexes based on key sequences are suggested. These indexes are simply vectors of numbers that are easily usable when matching two time series cases for case retrieval.

  • 139.
    Furunäs, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Adomat, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Lindh, Lennart
    Mälardalen University, Department of Computer Science and Electronics.
    Stärner, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Vörös, Peter
    Mälardalen University, Department of Computer Science and Electronics.
    A prototype for interprocess communication support, in hardware1997In: Proceedings - Euromicro Conference on Real-Time Systems, 1997, p. 18-24Conference paper (Refereed)
    Abstract [en]

    In message based systems, interprocess communication (IPC) is a central facility. If the IPC part is ineffective in such a system, it will decrease the performance and response time. By implementing the IPC facility in hardware, the administration (scheduling, message handling, time-out supervising etc.), is reduced on the CPU, which leads to more time left for the application and a more deterministic time behaviour. This paper describes a hardware implementation of asynchronous IPC in an RTU based architecture. RTU is a hardware implementation of a real-time kernel for uniprocessor and multiprocessor systems. In addition, our implementation of IPC supports message priority, priority inheritance on message arrival, and task time-out on message send/receive. An increased performance and message flow, in a message intense system, can be realized by implementing IPC functions in an RTU architecture.

  • 140.
    Furunäs-Åkesson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Interprocess Communication Utilising Special Purpose Hardware2001Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    Real-time systems are computer systems with constraints on the timing of actions. To ease the development and maintenance of application software, real-time systems often make use of a real-time operating system (RTOS). Its main task is management and scheduling of application processes (tasks). Other functions are interprocess communication, interrupt handling, memory management etc. Sometimes it is hard (or even impossible) to meet the time constraints specified for a real-time system, resulting in an incorrectly functioning application. A possible remedy is to redesign the system by upgrading the processor and/or remove functionality. An alternative approach is to use a special purpose hardware RTOS accelerator. The aim of such an accelerator is to speedup RTOS functions that impose big overhead i.e. to reduce the RTOS overhead by offloading the application processor. Accordingly, the processor gets more time for executing application software, and hopefully the time constraints can be met. The main drawback is the cost of extra hardware. This thesis presents results from implementing RTOS functions in hardware, especially interprocess communication (IPC) functions. The types of systems considered are uniprocessor and shared memory multiprocessor real-time systems. IPC is used in systems with co-operating processes. The real-time operating systems on the market support a large variation of IPC mechanisms. We will here present and evaluate three different IPC implementations. The first is an extended message queue mechanism that is used in commercial robot control applications. The second is the signal mechanism in OSE, a commercial RTOS predominantly used in telecommunication control applications, and the third is the semaphore and message queue mechanisms supported by the leading commercial RTOS VxWorks. All the implementations are based on a pre-emptive priority-based hardware real-time operating system accelerator. We show that it is not optimal, practical or desirable to implement every RTOS function in hardware, regarding systems in the scope of this thesis. However, an accelerator allows new functionality to be implemented. We illustrate this by implementing a message queue mechanism that supports priority inheritance for message arrival in hardware, which is too expensive to implement in software. Also, we show that substantial speedups are possible, and that a crucial mechanism in achieving speedup is the realisation of the communication between the accelerator and the processor. We further note that application speedups are possible, even in cases with an IPC-mechanism slow-down. The main reasons for this is that the accelerator can off-load the processor by handling the RTOS timing mechanism (clock-ticks), reducing the RTOS code to be executed on the processor, and handling interrupts.

  • 141.
    García Castaño, Javier
    Mälardalen University, Department of Computer Science and Electronics.
    Algorithms and Protocols Enhancing Mobility Support for Wireless Sensor Networks Based on Bluetooth and Zigbee2006Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Mobile communication systems are experiencing a huge growth. While traditional communication paradigms deal with fixed networks, mobility raises a new set of questions, techniques, and solutions. This work focuses on wireless sensor networks (WSNs) where each node is a mobile device. The main objectives of this thesis have been to develop algorithms and protocols enabling WSNs with a special interest in overcoming mobility support limitations of standards such as Bluetooth and Zigbee. The contributions of this work may be divided in four major parts related to mobility support. The first part describes the implementation of local positioning services in Bluetooth since local positioning is not supported in Bluetooth v1.1. The obtained results are used in later implemented handover algorithms in terms of deciding when to perform the handover. Moreover local positioning information may be used in further developed routing protocols. The second part deals with handover as a solution to overcome the getting out of range problem. Algorithms for handover have been implemented enabling mobility in Bluetooth infrastructure networks. The principal achievement in this part is the significant reduction of handover latency since sensor cost and quality of service are directly affected by this parameter. The third part solves the routing problems originated with handovers. The main contribution of this part is the impact of the Bluetooth scatternet formation and routing protocols, for multi-hop data transmissions, in the system quality of service. The final part is a comparison between Bluetooth and Zigbee in terms of mobility support. The main outcome of this comparison resides on the conclusions, which can be used as a technology election guide.

    The main scientific contribution relies on the implementation of a mobile WSN with Bluetooth v1.1 inside the scope of the ”Multi Monitoring Medical Chip (M3C) for Homecare Applications” European Union project (Sixth Framework Program (FP6) Reference: 508291) offering multi-hop routing support and improvements in handover latencies with aid of local positioning services.

  • 142.
    Gerdtman, Christer
    et al.
    Motion Control AB, Västerås, Sweden.
    Lindén, Maria
    Mälardalen University, Department of Computer Science and Electronics.
    A MEMS-gyro based computer mouse for disabled2006Conference paper (Refereed)
    Abstract [en]

    Computers are an important part of our daily lifes, and to be able to control them is in many cases necessary to be able to work, communicate or take part in our modern society of today. Therefore are persons that can not use an ordinary computer mouse in need of an alternative mouse. The reason of why an ordinary mouse can not be used is very different from person to person, depending on their abilities and needs. The need can also vary over time, not all persons are permanent handicapped, it can be a disability or bodily injury that can be healed. From these aspects, a computer mouse that can be used by a wide range of people with different types of disabilties and that can be applied on different body parts has been developed and evaulated.

  • 143.
    Gerdtman, Christer
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Lindén, Maria
    Mälardalen University, Department of Computer Science and Electronics.
    Development of a gyro sensor based computer mouse with USB interface interface as technical aid for disabled persons2005In: 3rd European Medical & Biological Engineering Conference (EMBEC’05), Vienna (Austria): Society for the Organization of the European Medical and Biological Engineering Conference EMBEC , 2005Conference paper (Refereed)
    Abstract [en]

    This paper describes the development of an alternative computer mouse for disabled persons. The mouse is an advanced technical aid for a large group of disabled (handicapped) persons, and can be placed on variuos suitable body parts. The mouse is module based and have many functions that enable a disabled persons to control a computer. It also allows the person to work efficent on the computer. The functions have been developed togehter with disabled persons and are based on their wishes and needs. Therfor it is not only a «head-mouse», it is an alternative mouse! The device is a gyro sensor based computer mouse and it operates by sensing the rotation of a body part. The disabled users appreciated the high sensitivity of the mouse and that it is easy to install and use, thanks the USB «plug&play» functionality. The mouse is a small and comfortable computer mouse that suits a various groups of disabled persons with different types of movement handicaps.

  • 144.
    Gerdtman, Christer
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Lindén, Maria
    Mälardalen University, Department of Computer Science and Electronics.
    Utveckling av en gyrobaserad datormus for funktionshindrade med begränsad rörelseförmåga2006Conference paper (Refereed)
    Abstract [en]

    Att kunna anvanda en dator ar ofta en forutsattning idag for att en person ska kunna utfora sitt arbete, ta del av information, kommunicera med andra och pa andra satt ta del av vart moderna samhalle. Darfor behover personer som inte kan anvanda en vanlig datormus, en alternativ inmatningsenhet for att kunna styra datorn. Personer med begransad rorelseformaga har behov av en mycket kanslig mus, som kan kanna av aven sma rorelser. Syftet med denna studie var att undersoka vilka kriterier som kan stallas pa en alternativ mus jamfort med en vanlig datormus som styrs via ena handen, att utveckla en prototyp samt att lata anvandarna prova och utvardera prototypen.

  • 145.
    Gorschek, Tony
    et al.
    Mälardalen University, Department of Computer Science and Electronics. Blekinge Institute of Technology, Sweden.
    Garre, Per
    Danaher Motion Särö AB, Sweden.
    Larsson, Stig
    ABB Corporate Research, Sweden.
    Wohlin, Claes
    Mälardalen University, Department of Computer Science and Electronics. Blekinge Institute of Technology, Sweden.
    Industry evaluation of the Requirements Abstraction Model2008In: Requirements Engineering Journal, ISSN 0947-3602, Vol. 12, no 3, p. 163-190Article in journal (Refereed)
    Abstract [en]

    Software requirements are often formulated on different levels and hence they are difficult to compare to each other. To address this issue, a model that allows for placing requirements on different levels has been developed. The model supports both abstraction and refinement of requirements, and hence requirements can both be compared with each other and to product strategies. Comparison between requirements will allow for prioritization of requirements, which in many cases is impossible if the requirements are described on different abstraction levels. Comparison to product strategies will enable early and systematic acceptance or dismissal of requirements, minimizing the risk for overloading. This paper presents an industrial evaluation of the model. It has been evaluated in two different companies, and the experiences and findings are presented. It is concluded that the requirements abstraction model provides helpful improvements to the industrial requirements engineering process.

  • 146.
    Granstedt, Fredrik
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Folke, Mia
    Mälardalen University, Department of Computer Science and Electronics.
    Bäcklund, Ylva
    Mälardalen University, Department of Computer Science and Electronics.
    Hök, Bertil
    Hök Instrument AB, Sweden.
    Gas sensor with electroacoustically coupled resonator2001In: Sensors and Actuators, ISSN 0925-4005, Vol. 78, p. 161-165Article in journal (Refereed)
    Abstract [en]

    A new configuration for a gas sensor is demonstrated. The configuration consists of an electroacoustic element coupled to an acoustic resonator, such as Kundt's tube, exhibiting a resonance frequency that is related to the velocity of sound, which, in turn is a function of the molecular mass of the gas within the resonator. Electrical impedance measurements were performed, whereby a resonance peak attributable to the resonator was identified. Contributing effects to the quality factor, Q, of the resonance, was analyzed. Predictable shifts of the resonance frequency were observed when adding CO2 and He to air, and when varying the resonator length. Linearity within the experimental accuracy was confirmed. The new sensor configuration offers the potential advantages of smaller size, improved dynamic response, and lower cost. © 2001 Elsevier Science B.V. All rights reserved.

  • 147.
    Gulbrandsen, Elisabeth
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Trojer, Lena
    Mälardalen University, Department of Computer Science and Electronics.
    Björkman, Christina
    Mälardalen University, Department of Computer Science and Electronics.
    Elovaara, Pirjo
    Mälardalen University, Department of Computer Science and Electronics.
    Genusforskning inom teknisk fakultet: en kunskapspolitisk utmaning2006In: Kvinnovetenskaplig Tidskrift, ISSN 0348-8365, Vol. 27, no 2/3, p. 49-64Article in journal (Refereed)
  • 148.
    Gunnarsson, Tommy
    Mälardalen University, Department of Computer Science and Electronics.
    MICROWAVE IMAGING OF BIOLOGICAL TISSUES: applied toward breast tumor detection2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Microwave imaging is an efficient diagnostic modality for non-invasively visualizing dielectric contrasts of non-metallic bodies. An increasing interest of this field has been observed during the last decades. Many application areas in biomedicine have been issued, recently the breast tumor detection application using microwave imaging.

    Many groups are working in the field at the moment for several reasons. Breast cancer is a major health problem globally for women, while it is the second most common cancer form for women causing 0.3 % of the yearly female death in Sweden. Medical imaging is considered as the most effective way of diagnostic breast tumors, where X-ray mammography is the dominating technique. However, this imaging modality still suffers from some limitations. Many women, mostly young ones, have radiographically dense breasts, which means that the breast tissues containing high rates of fibroglandular tissues. In this case the density is very similar to the breast tumor and the diagnosis is very difficult. In this case alternative modalities like Magnetic Resonance Imaging (MRI) with contrast enhancement and Ultrasound imaging are used, however those are not suitable for large scale screening program.Another limitation is the false-negative and false-positive rate using mammography, in general 5–15 % of the tumors are not detected and many cases have to go though a breast biopsy to verify a tumor diagnosis. At last the mammography using breast compression sometimes painful, and utilizing ionizing X-rays. The big potential in microwave imaging is the reported high contrast of complex permittivity between fibroglandular tissues and tumor tissues in breasts and that it is a non-ionizing method which probably will be rather inexpensive.

    The goal with this work is to develop a microwave imaging system able to reconstruct quantitative images of a female breast. In the frame of this goal this Licentiate thesis contains a brief review of the ongoing research in the field of microwave imaging of biological tissues, with the major focus on the breast tumor application. Both imaging algorithms and experimental setups are included. A feasibility study is performed to analyze what response levels could be expected, in signal properties, in a breast tumor detection application. Also, the usability of a 3D microwave propagation simulator, (QW3D), in the setup development is investigated. This is done by using a simple antenna setup with a breast phantom with different tumor positions. From those results it is clear that strong responses are obtained by a tumor presence and the diffracted responses gives strong information about inhomogeneities inside the breast. The second part of this Licentiate thesis is done in collaboration between Mälardalen University and Supélec. Using the existing planar 2.45 GHz microwave camera and the iterative non-linear Newton Kantorovich code, developed at Département de Recherches en Electromagnétisme (DRE) at Supélec, as a starting point, a new platform for both real-time qualitative imaging and quantitative images of inhomogeneous objects are investigated. The focusing is related to breast tumor detection. For the moment the tomographic performance of the planar camera is verified in simulations through a comparison with other setups. Good calibration is observed, but still experimental work concerning phantom development etc. is needed before experimental results on breast tumor detection may be obtained.

  • 149.
    Gunnarsson, Tommy
    Mälardalen University, Department of Computer Science and Electronics.
    Microwave Imaging of Biological Tissues: the current status in the research areaManuscript (Other academic)
  • 150.
    Gunnarsson, Tommy
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Joachimowicz, Nadine
    Diet, Antoine
    Conessa, Cristoph
    Åberg, Denny
    Bolomey, Jean Charles
    QUANTITATIVE IMAGING USING A 2.45 GHz PLANAR CAMERAManuscript (Other academic)
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