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  • 351.
    Granat, Robert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Kagstrom, Bo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kressner, Daniel
    Shao, Meiyue
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Algorithm 953: Parallel Library Software for the Multishift QR Algorithm with Aggressive Early Deflation2015Inngår i: ACM Transactions on Mathematical Software, ISSN 0098-3500, E-ISSN 1557-7295, Vol. 41, nr 4, artikkel-id 29Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Library software implementing a parallel small-bulge multishift QR algorithm with Aggressive Early Deflation (AED) targeting distributed memory high-performance computing systems is presented. Starting from recent developments of the parallel multishift QR algorithm [Granat et al., SIAM J. Sci. Comput. 32(4), 2010], we describe a number of algorithmic and implementation improvements. These include communication avoiding algorithms via data redistribution and a refined strategy for balancing between multishift QR sweeps and AED. Guidelines concerning several important tunable algorithmic parameters are provided. As a result of these improvements, a computational bottleneck within AED has been removed in the parallel multishift QR algorithm. A performance model is established to explain the scalability behavior of the new parallel multishift QR algorithm. Numerous computational experiments confirm that our new implementation significantly outperforms previous parallel implementations of the QR algorithm.

  • 352. Granat, Robert
    et al.
    Kågström, Bo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kressner, Daniel
    A novel parallel QR algorithm for hybrid distributed memory HPC systems2010Inngår i: SIAM Journal on Scientific Computing, ISSN 1064-8275, E-ISSN 1095-7197, Vol. 32, nr 4, s. 2345-2378Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel variant of the parallel QR algorithm for solving dense nonsymmetric eigenvalue problems on hybrid distributed high performance computing systems is presented. For this purpose, we introduce the concept of multiwindow bulge chain chasing and parallelize aggressive early deflation. The multiwindow approach ensures that most computations when chasing chains of bulges are performed in level 3 BLAS operations, while the aim of aggressive early deflation is to speed up the convergence of the QR algorithm. Mixed MPI-OpenMP coding techniques are utilized for porting the codes to distributed memory platforms with multithreaded nodes, such as multicore processors. Numerous numerical experiments confirm the superior performance of our parallel QR algorithm in comparison with the existing ScaLAPACK code, leading to an implementation that is one to two orders of magnitude faster for sufficiently large problems, including a number of examples from applications.

  • 353.
    Granat, Robert
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Kågström, Bo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Högpresterande beräkningscentrum norr (HPC2N).
    Kressner, Daniel
    ETH, Zürich.
    Parallel Eigenvalue Reordering in Real Schur Forms2009Inngår i: Concurrency and Computation, ISSN 1532-0626, E-ISSN 1532-0634, Vol. 21, nr 9, s. 1225-1250Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 354.
    Granberg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Learning Natural LanguageInterfaces over Expresive MeaningRepresentation Languages2010Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis focuses on learning natural language interfaces using synchronous

    grammars, l-calculus and statistical modeling of parse probabilities. A major

    focus of the thesis has been to replicate Mooney and Wong’s l-WASP [17] algorithm

    and implement it inside the C-PHRASE [12] Natural Language Interface

    (NLI) system. By doing this we can use C-PHRASE’s more expressive and transportable

    meaning representation language (MRL), rather than the PROLOG-based

    MRL Mooney and Wong used.

    Our system, the C-PHRASE LEARNER, relaxes some constraints in l-WASP

    to allow use of more flexible MRL grammars. We also reformulate the algorithm

    in terms of operations on trees to clarify and simplify the approach. We test the

    C-PHRASE LEARNER over the US geography corpus GEOQUERY and produce

    precision and recall results slightly below those achieved by l-WASP. This was

    expected as we have fewer domain restrictions due to our more expressive and

    portable MRL grammar.

    Our work on the C-PHRASE LEARNER system has also revealed some promising

    avenues of future research including, among others, alternative statistical alignment

    strategies, integrating linguistic theories into our learning algorithm and

    ways to improve named entity recognition. C-PHRASE LEARNER is presented

    as open source to the community to allow anyone to expand upon this work.

  • 355.
    Granberg, Marie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Automatiserad test av programbibliotek för processtyrning2010Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [sv]

    På ABB i Umeå programmeras styrsystem till bland annat tillverkningsindustrin och gruvbranschen. Varje styrsystem är unikt men vissa delar förekommer ofta, så för att inte programmerarna ska behöva skriva samma kod varje gång har det skapats funktionsblock av de kodbitarna. Funktionsblocken är samlade i olika funktionsblocksbibliotek. Biblioteken uppdateras med jämna mellanrum och alla funktionsblock behöver då testas så att inte ändringarna har påverkat de gamla funktionerna. Denna testning, som nu görs manuellt, tar mycket tid och är långt i från pålitlig. Problemställningen är därför att utreda i vilken utsträckning det går att automatisera dessa tester och hur detta skulle gå till.

    Efter att ha undersökt olika program som skulle kunna lämpa sig för automatiska tester visade det sig att det var mest lämpligt att använda ABB:s egna verktyg för att skapa testverktyget, delvis på grund av att det inte krävs något extra program för att få kommunikation mellan testprogrammet och funktionsblocket som skall testas.

    Testprogrammet byggs upp med ett antal nya funktionsblock och kan anslutas till blocken som ska testas. Ett test av ett funktionsblock består av en mängd olika testfall. Testprogrammet sätter funktionsblockets ingångar för att komma i rätt läge för ett testfall och kontrollerar sedan om utgångarna är som förväntat. Funktionsblocken innehåller även en del grafik för att operatörerna ska kunna kontrollera och styra systemet. Att helt automatisera grafiktesterna är avancerat och kräver andra verktyg. Testerna av grafik har därför inte automatiserats helt utan testprogrammet sätter funktionsblocket i rätt läge för testfallet och sedan får användaren kontrollera grafiken och fylla i de fel som finns i det nyskapade användargränssnittet. Användaren behöver därigenom inte styra några funktionsblock under testet utan bara studera grafiken. Resultatet från funktions- och grafiktesterna presenteras i en händelselista efter testet är avslutat.

    En del av arbetet har även gått ut på att undersöka om och hur det skulle vara möjligt att automatisera tester av anläggningsapplikationer, där anläggningsapplikationen är det färdiga systemet som levereras till kunden dvs. funktionsblock och övrig kod. Detta skulle delvis vara möjligt att genomföra genom att läsa in de korrekta inställningarna från en konstruktionsbeskrivning för att sen jämföra de med inställningarna i systemet. Men vissa av inställningarna är svåra att testa eftersom de kräver att flera funktionsblock är i rätt läge. Att skapa ett automatiskt test för anläggningsapplikationer skulle vara komplicerat och ta lång tid men om man väljer att skapa ett sådant program skulle man lika gärna kunna skapa ett program som lägger in inställningarna direkt i stället för att bara kontrollera dem. Ett alternativ kan vara att göra ett automatiskt test endast för de enklare testfallen vilket skulle spara en hel del tid från de manuella testerna.

  • 356.
    Grundel, Markus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Interaktionsdesign för kommersiella webbtjänster2010Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The company Microshop is interested in implementing new features in their product-website, and would like to examine the possibility and usefulness of introducing such functionality. When designing interaction for commercial websites, it is important to make the menus easy to use, and refrain from using deep hierarchies in order to avoid causing unnecessary burden for the users. There is an interest among users for adaptive functionality, but this requires great amounts of trust in the website from the user. Something which can be created by refraining from using implicit information, and provide detailed explanations throughout the website. A usability test was conducted in order to complement the data gathered from the theoretical study, the interviews and the expert evaluations. This test evaluated the interface design and the necessity of the proposed functionality. The test was carried out under controlled conditions, and was conducted as a series of user observations of the trial participants. Results showed that there is a need for adaptive functionality, but that the existing interface requires an update before additional functionality is introduced. Proposals on how this could be solved are presented as a number of design proposals which would address the problems, and propose a design for the new features. The usability test proved extremely capable of identifying errors that occurred when the participants corrected their previous actions. In addition, the users trust in the interface, and their previous computer experience contributed to interesting results.

  • 357.
    Guerrero, Esteban
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Practical reasoning about complex activities2017Inngår i: Advances in Practical Applications of Cyber-Physical Multi-Agent Systems: The PAAMS Collection / [ed] Yves Demazeau, Paul Davidsson, Javier Bajo, Zita Vale, Cham: Springer International Publishing AG , 2017, s. 82-94Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we present an argument-based mechanism to generate hypotheses about belief-desire-intentions on dynamic and complex activities of a software agent. We propose to use a composed structure called activity as unit for agent deliberation analysis, maintaining actions, goals and observations of the world always situated into a context. Activity transformation produces changes in the knowledge base activity structure as well in the agent’s mental states. For example, in car driving as a changing activity, experienced and novice drivers have a different mental attitudes defining distinct deliberation processes with the same observations of the world. Using a framework for understanding activities in social sciences, we endow a software agent with the ability of deliberate, drawing conclusion about current and past events dealing with activity transformations. An argument-based deliberation is proposed which progressively reason about activity segments in a bottom-up manner. Activities are captured as extended logic programs and hypotheses are built using an answer-set programming approach. We present algorithms and an early-stage implementation of our argument-based deliberation process.

  • 358.
    Guerrero, Esteban
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    ALI, an ambient assisted living system for supporting behavior change2013Inngår i: VIII Workshop on Agents Applied in Health Care (A2HC 2013), 2013, s. 81-92Konferansepaper (Fagfellevurdert)
  • 359.
    Guerrero, Esteban
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    ALI, an Assisted Living System Based on a Human-Centric Argument-Based Decision Making Framework2013Inngår i: 13th Workshop on Computational Models of Natural Arguments (CMNA 2013), 2013, s. 46-51Konferansepaper (Fagfellevurdert)
  • 360.
    Guerrero, Esteban
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    ALI: an assisted living system for persons with mild cognitive impairment2013Inngår i: 2013 IEEE 26th International symposium on computer-based medical systems (CBMS), 2013, s. 526-527Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We introduce the Assisted Living system ALI, which is a novel approach to providing assistance and support in activities of daily life. We integrate a human behavior theory with a default reasoning decision making framework. This integration allows us to model a decision making problem from a human activity centric point of view and at the same time, formalize these elements using a possibilistic argumentation theory. ALI sends personalized notifications suggesting the most suitable activities to perform and determines what activities were performed during a time period.

  • 361.
    Guerrero, Esteban
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    ALI: an Assisted Living System for Persons with Mild Cognitive Impairment2013Inngår i: 26th IEEE International Symposium on Computer-Based Medical Systems (CBMS 2013), IEEE Computer Society, 2013, s. 526-527Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We introduce the Assisted Living system ALI, which is a novel approach to providing assistance and support in activities of daily life. We integrate a human behavior theory with a default reasoning decision making framework. This integration allows us to model a decision making problem from a human activity centric point of view and at the same time, formalize these elements using a possibilistic argumentation theory. ALI sends personalized notifications suggesting the most suitable activities to perform and determines what activities were performed during a time period.

  • 362.
    Guerrero, Esteban
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    An activity-centric argumentation framework for assistive technology aimed at improving health2016Inngår i: Argument & Computation, ISSN 1946-2174, Vol. 7, nr 1, s. 5-33Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tailoring assistive systems for guiding and monitoring an individual in daily living activities is a complex task. This paper presents ALI, an assistive system combining a formal possibilistic argumentation system and an informal model of human activity: the Cultural-Historic Activity Theory, facilitating the delivery of tailored advices to a human actor. We follow an activity-centric approach, taking into consideration the human’s motives, goals and prioritized actions. ALI tracks a person in order to I) determine what activities were performed over a period of time (activity recognition tracking), and II) send personalized notifications suggesting the most suitable activities to perform (decision-making monitoring). The ALI system was evaluated in a formative pilot study related to promote social activities and physical exercise.

  • 363.
    Guerrero, Esteban
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Arguing through the well-founded semantics: an argumentation engine2014Artikkel i tidsskrift (Fagfellevurdert)
  • 364.
    Guerrero, Esteban
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Semantic-based construction of arguments: an answer set programming approach2015Inngår i: International Journal of Approximate Reasoning, ISSN 0888-613X, E-ISSN 1873-4731, Vol. 64, s. 54-74Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we introduce an argumentation approach which takes an extended logic program as input and gives a set of arguments with the respective disagreements among them as output. We establish the notion of an argument under the Well-Founded semantics and Stable semantics inferences, allowing us to identify arguments with stratified programs as support, even when the input for the argument engine is a non-stratified program. We propose a set of rationality postulates for argument-based systems under extended logic programs, which are based on a definition of closure for a set of clauses that consider the well-known Gelfond-Lifschitz reduction. We establish the conditions under which our approach satisfies these principles. In addition, we present a standalone argumentation-tool based on the XSB system which implements our argumentation approach.

  • 365.
    Guerrero, Esteban
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Sandlund, Marlene
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Fysioterapi.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Activity qualifiers in an argumentation framework as instruments for agents when evaluating human activity2016Inngår i: Advances in Practical Applications of Scalable Multi-agent Systems. The PAAMS Collection: 14th International Conference, PAAMS 2016, Sevilla, Spain, June 1-3, 2016, Proceedings / [ed] Yves Demazeau, Takayuki Ito, Javier Bajo, Maria José Escalona, Springer, 2016, Vol. 9662, s. 133-144Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Theoretical frameworks have been developed for enabling software agents to evaluate simple activities such as walking and sitting. However, such frameworks typically do not include methods for how practically dealing with uncertain sensor information. We developed an argument-based method for evaluating complex goal-based activities by adapting two qualifiers: Performance and Capacity defined in the health domain. The first one evaluates what a person does, and the second one how "well" or "bad" an activity is executed. Our aim is to deal with uncertainty and inconsistent information; generate consistent hypotheses about the activity execution; and resemble an expert therapist judgment, where an initial hypothesis assessment can be retracted under new evidence. We conducted a pilot test in order to evaluate our approach using a Physiotherapy assessment test as a goal-based activity. Results show that skeptic argumentation semantics are may be useful for discriminating individuals without physical issues by considering Performance and Capacity; conversely, credulous semantics may be suitable for obtaining information in the evaluation of activity, which an intelligent agent may use for providing personalized assistance in an ambient assisted living environment.

  • 366.
    Guerrero, Esteban
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nieves, Juan Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Sandlund, Marlene
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Fysioterapi.
    Lindgren, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Activity qualifiers using an argument-based construction2018Inngår i: Knowledge and Information Systems, ISSN 0219-1377, E-ISSN 0219-3116, Vol. 54, nr 3, s. 633-658Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Based on an argumentation theory approach, we present a novel method for evaluating complex goal-based activities by generalizing a notion of qualifier defined in the health domain. Three instances of the general qualifier are proposed: Performance, Actuation and Capacity; the first one evaluates what a person does, the second how an individual follows an action plan, and the third one how "well" or "bad" an activity is executed. Qualifiers are intended to be used by autonomous systems for evaluating human activity. We exemplify our approach using a health domain assessment protocol. Main results of this test show a partial correlation between ambiguities assessed by experts and our argument-based approach; and a multi-dimensional perspective how an activity is executed when a combined evaluation of qualifiers is used. This last outcome was interesting for some therapists consulted. Results also show differences between values of qualifiers using different argumentation semantics; two scenarios were proposed by therapist for using different semantics: preliminary activity screening and time-span follow-up evaluation.

  • 367.
    Guerrero Rosero, Esteban
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Representing and Reasoning about Complex Human Activities - an Activity-Centric Argumentation-Based Approach2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aim of this thesis is to develop theories and formal methods to endow a computing machinery with capabilities to identify, represent, reason and evaluate complex activities that are directed by an individual’s needs, goals, motives, preferences and environment, information which can be inconsistent and incomplete.

    Current methods for formalising and reasoning about human activity are typically limited to basic actions, e.g., walking, sitting, sleeping, etc., excluding elements of an activity. This research proposes a new formal activity-centric model that captures complex human activity based on a systemic activity structure that is understood as a purposeful, social, mediated, hierarchically organized and continuously developing interaction between people and word.

    This research has also resulted in a common-sense reasoning method based on argumentation, in order to provide defeasible explanations of the activity that an individual performs based on the activity-centric model of human activity. Reasoning about an activity is based on the novel notion of an argument under semantics-based inferences that is developed in this research, which allows the building of structured arguments and inferring consistent conclusions.

    Structured arguments are used for explaining complex activities in a bottom-up manner, by introducing the notion of fragments of activity. Based on these fragments, consistent argumentation based interpretations of activity can be generated, which adhere to the activity-centric model of complex human activity.

    For resembling the kind of deductive analysis that a clinician performs in the assessment of activities, two quantitative measurements for evaluating performance and capacity are introduced and formalized. By analysing these qualifiers using different argumentation semantics, information useful for different purposes can be generated. e.g., such as detecting risk in older adults for falling down, or more specific information about activity performance and activity completion. Both types of information can form the base for an intelligent machinery to provide tailored recommendation to an individual.

    The contributions were implemented in different proof-of-concept systems, designed for evaluating complex activities and improving individual’s health in daily life. These systems were empirically evaluated with the purpose of evaluating theories and methodologies with potential users. The results have the potential to be utilized in domains such as ambient assisted living, assistive technology, activity assessment and self-management systems for improving health.

  • 368.
    Guerrero Rosero, Esteban
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Supporting human activity performance using argumentation-based technology2014Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aim for the research presented in this thesis is to develop theories, methods and technology which can detect, represent and evaluate purposeful human activity based on information, which is inconsistent, incomplete and which includes information about an individual's needs, goals and motives. The purpose is to provide instruments to the fields of assistive technology and ambient assisted living, which have the potentials to advance the treatment of semantic information for the purpose of making decisions and reasoning about complex human activity in daily life. Furthermore, based on sound interpretations of activity and evaluation of activity performance, tailored recommendations can be provided to the individual. This is achieved by integrating theoretical models of human activity with formal argumentation theory, and in this way create a model for representing the knowledge. Also based on the activity-theoretical models of human activity and argumentation, a computational model for common-sense reasoning was built based on the notion of fragments of activity. Moreover, a calculus model for evaluating activity performance considering the so called activity fragments was developed. These theoretical models were forming a base for implementing an argument-based reasoner engine, which manages incomplete and inconsistent information. These results were implemented in a prototype system designed for aiding an individual in improving health in daily life, for the purpose of testing the theories and methodologies with potential users. Information obtained by the sensors of a mobile phone and by assessments done by the individual regarding priorities, goals and motives were used in the analysis. Preliminary results are fed into further development, and future work includes user studies over a longer period of time. Furthermore, assistive technology for monitoring human activities in different contexts such as mining and construction industries are also being developed and tested. Future work includes also the development of methods for reasoning about activities based on data-stream sources, and taking into account that human needs, goals and motives vary over time. Moreover, methods for automatic configuration of intelligent collaborative agents and for fusing of heterogeneous data sources for providing tailored services will also be developed and evaluated in the ambient assisted living context.

  • 369.
    Gunnarsson, Morgan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
     Robot Design Optimization by means of a Genetic Algorithm and Physics Simulation2010Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis presents a new robot design paradigm that utilizes evolutionary optimization techniques and advanced physics simulations. This technology makes it possible to design and test robots in virtual environments before the physical robots are built, which enables robot manufacturers to improve the performance of their products and decrease the time and cost for development. In this project, a 3D robot model was defined in geometric, kinematic and dynamic terms. Also, a piece of software was developed in C++ to optimize the robot design, and to simulate and visualize the robot model with the aid of a physics engine. A genetic algorithm was developed for the optimization and used to minimize the average positional error and the total torque magnitude under constraints on speed, and the design variables were the PID controller parameters and the torque actuator limits. Only predefined robots can be programmed and simulated with current software packages for offline-programming and robot simulation. It was concluded that such software packages can be improved by robot design optimization using the software developed in this project, by means of a genetic algorithm and simulations using a physics engine.

  • 370.
    Gusev, Sergei
    et al.
    Department of Mathematics and Mechanics, St. Petersburg State University, St. Petersburg, Russia.
    Johansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kågström, Bo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Shiriaev, Anton
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Varga, Andras
    Institute of Robotics and Mechatronics, German Aerospace Center, DLR, Germany.
    A numerical evaluation of solvers for the periodic riccati differential equation2010Inngår i: BIT Numerical Mathematics, ISSN 0006-3835, E-ISSN 1572-9125, Vol. 50, nr 2, s. 301-329Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Efficient and accurate structure exploiting numerical methods for solvingthe periodic Riccati differential equation (PRDE) are addressed. Such methods areessential, for example, to design periodic feedback controllers for periodic controlsystems. Three recently proposed methods for solving the PRDE are presented andevaluated on challenging periodic linear artificial systems with known solutions and applied to the stabilization of periodic motions of mechanical systems. The first twomethods are of the type multiple shooting and rely on computing the stable invariantsubspace of an associated Hamiltonian system. The stable subspace is determinedusing either algorithms for computing an ordered periodic real Schur form of a cyclicmatrix sequence, or a recently proposed method which implicitly constructs a stabledeflating subspace from an associated lifted pencil. The third method reformulatesthe PRDE as a convex optimization problem where the stabilizing solution is approximatedby its truncated Fourier series. As known, this reformulation leads to a semidefiniteprogramming problem with linear matrix inequality constraints admitting aneffective numerical realization. The numerical evaluation of the PRDE methods, withfocus on the number of states (n) and the length of the period (T ) of the periodicsystems considered, includes both quantitative and qualitative results.

  • 371.
    Gusev, Sergei
    et al.
    Department of Mathematics and Mechanics, St. Petersburg State University, St. Petersburg, Russia.
    Johansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kågström, Bo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Shiriaev, Anton
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Varga, Andras
    Institute of Robotics and Mechatronics, German Aerospace Center, DLR, Oberpfaffenhofen, Germany.
    A Numerical Evaluation of Solvers for the Periodic Riccati Differential Equation2009Rapport (Annet vitenskapelig)
    Abstract [en]

    Efficient and robust numerical methods for solving the periodic Riccati differential equation (PRDE) are addressed. Such methods are essential, for example, when deriving feedback controllers for orbital stabilization of underactuated mechanical systems. Two recently proposed methods for solving the PRDE are presented and evaluated on artificial systems and on two stabilization problems originating from mechanical systems with unstable dynamics. The first method is of the type multiple shooting and relies on computing the stable invariant subspace of an associated Hamiltonian system. The stable subspace is determined using algorithms for computing a reordered periodic real Schur form of a cyclic matrix sequence, and a recently proposed method which implicitly constructs a stable subspace from an associated lifted pencil. The second method reformulates the PRDE as a maximization problem where the stabilizing solution is approximated with finite dimensional trigonometric base functions. By doing this reformulation the problem turns into a semidefinite programming problem with linear matrix inequality constraints.

  • 372.
    Gustavson, Fred G.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Wasniewski, Jerzy
    Dongarra, Jack J.
    Herrero, Jose R.
    Langou, Julien
    Level-3 Cholesky Factorization Routines Improve Performance of Many Cholesky Algorithms2013Inngår i: ACM Transactions on Mathematical Software, ISSN 0098-3500, E-ISSN 1557-7295, Vol. 39, nr 2, s. 9-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Four routines called DPOTF3i, i = a, b, c, d, are presented. DPOTF3i are a novel type of level-3 BLAS for use by BPF (Blocked Packed Format) Cholesky factorization and LAPACK routine DPOTRF. Performance of routines DPOTF3i are still increasing when the performance of Level-2 routine DPOTF2 of LAPACK starts decreasing. This is our main result and it implies, due to the use of larger block size nb, that DGEMM, DSYRK, and DTRSM performance also increases! The four DPOTF3i routines use simple register blocking. Different platforms have different numbers of registers. Thus, our four routines have different register blocking sizes. BPF is introduced. LAPACK routines for POTRF and PPTRF using BPF instead of full and packed format are shown to be trivial modifications of LAPACK POTRF source codes. We call these codes BPTRF. There are two variants of BPF: lower and upper. Upper BPF is "identical" to Square Block Packed Format (SBPF). "LAPACK" implementations on multicore processors use SBPF. Lower BPF is less efficient than upper BPF. Vector inplace transposition converts lower BPF to upper BPF very efficiently. Corroborating performance results for DPOTF3i versus DPOTF2 on a variety of common platforms are given for n approximate to nb as well as results for large n comparing DBPTRF versus DPOTRF.

  • 373.
    Gustavson, Fred G.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Wasniewski, Jerzy
    Dongarra, Jack J.
    Langou, Julien
    Rectangular Full Packed Format for Cholesky's Algorithm: Factorization, Solution, and Inversion2010Inngår i: ACM Transactions on Mathematical Software, ISSN 0098-3500, E-ISSN 1557-7295, Vol. 37, nr 2, s. 1-21, artikkel-id 18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We describe a new data format for storing triangular, symmetric, and Hermitian matrices called Rectangular Full Packed Format (RFPF). The standard two-dimensional arrays of Fortran and C (also known as full format) that are used to represent triangular and symmetric matrices waste nearly half of the storage space but provide high performance via the use of Level 3 BLAS. Standard packed format arrays fully utilize storage (array space) but provide low performance as there is no Level 3 packed BLAS. We combine the good features of packed and full storage using RFPF to obtain high performance via using Level 3 BLAS as RFPF is a standard full-format representation. Also, RFPF requires exactly the same minimal storage as packed the format. Each LAPACK full and/or packed triangular, symmetric, and Hermitian routine becomes a single new RFPF routine based on eight possible data layouts of RFPF. This new RFPF routine usually consists of two calls to the corresponding LAPACK full-format routine and two calls to Level 3 BLAS routines. This means no new software is required. As examples, we present LAPACK routines for Cholesky factorization, Cholesky solution, and Cholesky inverse computation in RFPF to illustrate this new work and to describe its performance on several commonly used computer platforms. Performance of LAPACK full routines using RFPF versus LAPACK full routines using the standard format for both serial and SMP parallel processing is about the same while using half the storage. Performance gains are roughly one to a factor of 43 for serial and one to a factor of 97 for SMP parallel times faster using vendor LAPACK full routines with RFPF than with using vendor and/or reference packed routines.

  • 374. Gähler, Werner
    et al.
    Eklund, Patrik
    Extension structures and compactifications2001Inngår i: Proceedings Joint 9th IFSA World Congress and 20th NAFIPS International Conference (Vol. 5), 2001, s. 2940-2945Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Basic results on compactifications are presented applying the notion of extension structure. Eachextension structure has a canonical completion. The related completion constructions can be applied, for instance, for generating completion theorems in algebra, lattice theory and general topology, in particular they lead to a universal completion for Cauchy-spaces in the fuzzy filter case. Sincecompactifications can be identified with special Cauchy-completions, even different types ofcompactifications can be generated. Among others, we present new results on the Richardson compactification in the fuzzy filter case applying new results on fuzzy filters. This type of compactification was treated previously by the authors (1993)

  • 375.
    Haake, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Björk, Peter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Karlsson, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Demonstration abstract: positioning by synchronized IR light2014Inngår i: Proceedings of the 13th International Symposium on Information Processing in Sensor Networks (IPSN' 14), IEEE conference proceedings, 2014, s. 335-336Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we will describe a positioning system based on synchronized IR light. Each node will be assigned a timeslot where they will send out an IR light. There is an IR camera that is also synchronized to the timeslots that will detect the position of each node and the ID that corresponds to the timeslot. To synchronize the clock of all nodes an IR flashlight is sent out that is detected by a photodiode on the nodes. The demo will show live video stream from a network camera where the ID and position of each node in view will be overlaid in real-time in the video.

  • 376.
    Halawani, Alaa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Computer Engineering Department, Palestine Polytechnic University, Hebron, Palestine.
    Li, Haibo
    KTH.
    100 lines of code for shape-based object localization2016Inngår i: Pattern Recognition, ISSN 0031-3203, E-ISSN 1873-5142, Vol. 60, s. 458-472Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We introduce a simple and effective concept for localizing objects in densely cluttered edge images based on shape information. The shape information is characterized by a binary template of the object's contour, provided to search for object instances in the image. We adopt a segment-based search strategy, in which the template is divided into a set of segments. In this work, we propose our own segment representation that we callone-pixel segment (OPS), in which each pixel in the template is treated as a separate segment. This is done to achieve high flexibility that is required to account for intra-class variations. OPS representation can also handle scale changes effectively. A dynamic programming algorithm uses the OPS representation to realize the search process, enabling a detailed localization of the object boundaries in the image. The concept's simplicity is reflected in the ease of implementation, as the paper's title suggests. The algorithm works directly with very noisy edge images extracted using the Canny edge detector, without the need for any preprocessing or learning steps. We present our experiments and show that our results outperform those of very powerful, state-of-the-art algorithms.

  • 377.
    Halawani, Alaa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    School of Computer Science & Communication, Royal Institute of Technology (KTH), Sweden.
    FingerInk: Turn your Glass into a Digital Board2013Inngår i: Proceedings of the 25th OzCHI conference: Augmentation, Application, Innovation, Collaboration, ACM Digital Library, 2013, s. 393-396Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a robust vision-based technology for hand and finger detection and tracking that can be used in many CHI scenarios. The method can be used in real-life setups and does not assume any predefined conditions. Moreover, it does not require any additional expensive hardware. It fits well into user's environment without major changes and hence can be used in ambient intelligence paradigm. Another contribution is the interaction using glass which is a natural, yet challenging environment to interact with. We introduce the concept of ``invisible information layer" embedded into normal window glass that is used as an interaction medium thereafter.

  • 378.
    Halawani, Alaa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Personal Relative Time: Towards Internet of Watches2011Inngår i: 2011 IEEE International Conferences on Internet of Things and Cyber, Physical and Social Computing, Los Alamitos: IEEE Computer Society, 2011, s. 678-682Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We introduce an idea for connecting timekeeping devices through the Internet, aiming at assigning people their individual personal time to loosen the strict rule of time synchronization that, in many cases, causes problems in access of available resources. Information about these resources, users, and their plans are utilized to accomplish the task. Time scheduling to assign users their individual time and readjustment of their timekeeping devices is done implicitly so that they do not feel any abnormal changes during their day. This will lead to a nonlinear relationship between real (absolute) time and personal time. We explain the concept, give examples, and suggest a framework for the system.

  • 379.
    Halawani, Alaa
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    Active Vision for Tremor Disease Monitoring2015Inngår i: 6th International Conference on Applied Human Factors and Ergonomics (AHFE 2015) and the Affiliated Conferences AHFE 2015, 2015, Vol. 3, s. 2042-2048Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this work is to introduce a prototype for monitoring tremor diseases using computer vision techniques.  While vision has been previously used for this purpose, the system we are introducing differs intrinsically from other traditional systems. The essential difference is characterized by the placement of the camera on the user’s body rather than in front of it, and thus reversing the whole process of motion estimation. This is called active motion tracking. Active vision is simpler in setup and achieves more accurate results compared to traditional arrangements, which we refer to as “passive” here. One main advantage of active tracking is its ability to detect even tiny motions using its simple setup, and that makes it very suitable for monitoring tremor disorders. 

  • 380.
    Hansson, Patrik
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Juslin, Peter
    Winman, Anders
    Probability intervals and sample constraints2004Inngår i: Proceedings of the twenty-sixth annual conference of the cognitive science society / [ed] Forbus, K; Gentner, D; Regier, T, Mahwah: Lawrence Erlbaum Associates, 2004, s. 1567-1567Konferansepaper (Fagfellevurdert)
  • 381.
    Hassan, Emadeldeen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Topology optimization of antennas and waveguide transitions2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis introduces a topology optimization approach to design, from scratch, efficient microwave devices, such as antennas and waveguide transitions. The design of these devices is formulated as a general optimization problem that aims to build the whole layout of the device in order to extremize a chosen objective function. The objective function quantifies some required performance and is evaluated using numerical solutions to the 3D~Maxwell's equations by the finite-difference time-domain (FDTD) method. The design variables are the local conductivity at each Yee~edge in a given design domain, and a gradient-based optimization method is used to solve the optimization problem. In all design problems, objective function gradients are computed based on solutions to adjoint-field problems, which are also FDTD discretization of Maxwell's equations but solved with different source excitations. For any number of design variables, the computation of the objective function gradient requires one solution to the original field problem and one solution to the associated adjoint-field problem. The optimization problem is solved iteratively using the globally convergent Method of Moving Asymptotes (GCMMA).

    By the proposed approach, various design problems, including tens of thousands of design variables, are formulated and solved in a few hundred iterations. Examples of solved design problems are the design of wideband antennas, dual-band microstrip antennas, wideband directive antennas, and wideband coaxial-to-waveguide transitions. The fact that the proposed approach allows a fine-grained control over the whole layout of such devices results in novel devices with favourable performance. The optimization results are successfully verified with a commercial software package. Moreover, some devices are fabricated and their performance is successfully validated by experiments.

  • 382.
    Hassan, Emadeldeen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Noreland, Daniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Augustine, Robin
    Uppsala University.
    Wadbro, Eddie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Berggren, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Topology optimization of planar antennas for wideband near-field coupling2015Inngår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 63, nr 9, s. 4208-4213Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present an approach to design from scratch planar microwave antennas for the purpose of ultra-wideband (UWB) near-field sensing. Up to about 120 000 design variables associated with square grids on planar substrates are subject to design, and a numerical optimization algorithm decides, after around 200 iterations, for each edge in the grid whether it should consist of metal or a dielectric. The antenna layouts produced with this approach show UWB impedance matching properties and near-field coupling coefficients that are flat over a much wider frequency range than a standard UWB antenna. The properties of the optimized antennas are successfully cross-verified with a commercial software and, for one of the designs, also validated experimentally. We demonstrate that an antenna optimized in this way shows a high sensitivity when used for near-field detection of a phantom with dielectric properties representative of muscle tissue.

  • 383.
    Hassan, Emadeldeen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Department of electronics and electrical communications, Menoufia University, Menouf, 32952, Egypt.
    Noreland, Daniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Wadbro, Eddie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Berggren, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Topology Optimisation of Wideband Coaxial-to-Waveguide Transitions2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikkel-id 45110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To maximize the matching between a coaxial cable and rectangular waveguides, we present a computational topology optimisation approach that decides for each point in a given domain whether to hold a good conductor or a good dielectric. The conductivity is determined by a gradient-based optimisation method that relies on finite-difference time-domain solutions to the 3D Maxwell’s equations. Unlike previously reported results in the literature for this kind of problems, our design algorithm can efficiently handle tens of thousands of design variables that can allow novel conceptual waveguide designs. We demonstrate the effectiveness of the approach by presenting optimised transitions with reflection coefficients lower than −15dB over more than a 60% bandwidth, both for right-angle and end-launcher configurations. The performance of the proposed transitions is crossverified with a commercial software, and one design case is validated experimentally.

  • 384.
    Hassan, Emadeldeen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Wadbro, Eddie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Berggren, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Conductive material distribution optimization for ultrawideband antennas2013Inngår i: Proceedings 11th International Conference on Mathematical and Numerical Aspects of Waves: Waves 2013, Tunis: ENIT-LAMSIN , 2013, s. 171-172Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An Ultrawideband (UWB) planar monopole an-tenna is designed using the material distribution ap-proach to topology optimization. The design variablesare the local conductivity values in a 75 × 75 mm areawhere the radiating element can be located. Theantenna is optimized for maximum reception, in anattached coaxial cable, of incoming plane waves. Thewave propagation is modeled using the time domain3D Maxwell equations discretized using FDTD, andthe optimization is carried out using a gradient-basedoptimization method, in which the derivatives aresupplied through solving corresponding adjoint equa-tions. The outer dimensions of the optimized antennais 75 × 60 mm, and its reflection coefficient |S11 |,with respect to a feeding signal in the coaxial cable,stays below −10 dB throughout the frequency band1.2–9.7 GHz.

  • 385.
    Hassan, Emadeldeen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Wadbro, Eddie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Berggren, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Patch and ground plane design of microstrip antennas by material distribution topologly optimization2014Inngår i: Progress in Electromagnetics Research B, ISSN 1937-6472, E-ISSN 1937-6472, Vol. 59, s. 89-102Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We use a gradient-based material distribution approach to design conductive parts of microstrip antennas in an efficient way. The approach is based on solutions of the 3D Maxwell's equation computed by the finite-difference time-domain (FDTD) method. Given a set of incoming waves, our objective is to maximize the received energy by determining the conductivity on each Yee-edge in the design domain. The objective function gradient is computed by the adjoint-field method. A microstrip antenna is designed to operate at 1.5 GHz with 0.3 GHz bandwidth. We present two design cases. In the first case, the radiating patch and the finite ground plane are designed in two separate phases, whereas in the second case, the radiating patch and the ground plane are simultaneously designed. We use more than 58,000 design variables and the algorithm converges in less than 150 iterations. The optimized designs have impedance bandwidths of 13% and 36% for the first and second design case, respectively.

  • 386.
    Hassan, Emadeldeen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Wadbro, Eddie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Berggren, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Time-Domain Sensitivity Analysis for Conductivity Distribution in Maxwell's Equations2015Rapport (Annet vitenskapelig)
    Abstract [en]

    We present expressions for the derivatives of the outgoing signal in coaxial cables with respect to the conductivity distribution in a specific domain. The derived expressions can be used with gradient-based optimization methods to design metallic electromagnetic devices, such as antennas and waveguides. We use the adjoint-field method to derive the expressions and the derivation is based on the 3D time-domain Maxwell's equations. We present two derivative expressions; one expression is derived in the continuous case and the second is derived based on the FDTD discretization of Maxwell's equations, including the uniaxial perfectly match layer (UPML) to simulate the radiation boundary condition. The derivatives are validated through a numerical example, where derivatives computed by the adjoint-field method are compared against derivatives computed with finite differences. Up to 7 digits precision matching is obtained.

  • 387.
    Hassan, Emadeldeen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Wadbro, Eddie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Berggren, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Topology optimization of metallic antennas2014Inngår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 62, nr 5, s. 2488-2500Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We introduce an approach to carry out layout optimization of metallic antenna parts. An optimization technique first developed for the optimization of load-bearing elastic structures is adapted for the purpose of metallic antenna design. The local conductivity values in a given region are used as design variables and are iteratively updated by a gradient-based optimization algorithm. Given a set of time-domain signals from exterior sources, the design objective is here to maximize the energy received by the antenna and transmitted to a coaxial cable. The optimization proceeds through a sequence of coarsely-defined lossy designs with successively increasing details and less losses as the iterations proceed. The objective function gradient is derived based on the FDTD discretization of Maxwell's equations and is expressed in terms of field solutions of the original antenna problem and an adjoint field problem. The same FDTD code, but with different wave sources, is used for both the original antenna problem and the adjoint problem. For any number of design variables, the gradient is evaluated on the basis of only two FDTD simulations, one for the original antenna problem and another for the adjoint field problem. We demonstrate the capability of the method by optimizing the radiating patch of both UWB monopole and microstrip antennas. The UWB monopole is designed to radiate over a wide frequency band 1-10 GHz, while the microstrip patch is designed for single and dual frequency band operation. In these examples, there are more than 20,000 design variables, and the algorithm typically converges in less than 150 iterations. The optimization results show a promising use of the proposed approach as a general method for conceptual design of near-resonance metallic antennas.

  • 388.
    Hassan, Emadeldeen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Wadbro, Eddie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Berggren, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Topology optimization of UWB monopole antennas2013Inngår i: 7th European Conference on Antennas and Propagation (EuCAP2013), New York: IEEE conference proceedings, 2013, s. 1488-1492Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A Topology optimization technique is used for complete layout optimization of the radiating element of a planar monopole antenna. The design objective is to find a conductivity distribution that maximizes the energy received by the planar monopole over the frequency band 1-10 GHz. The finite difference time domain method (FDTD) is used for the numerical calculations, and an adjoint problem is derived to calculate the corresponding sensitivities. Numerical results show a promising use of topology optimization techniques for the systematic design of ultrawideband monopoles.

  • 389.
    Hassan, Emadeldeen
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Department of Electronics and Electrical Communications, Menoufia University, Menouf, Egypt.
    Wadbro, Eddie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hägg, Linus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Berggren, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Topology optimization of compact wideband coaxial-to-waveguide transitions with minimum-size control2018Inngår i: Structural and multidisciplinary optimization (Print), ISSN 1615-147X, E-ISSN 1615-1488, Vol. 57, nr 4, s. 1765-1777Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a density-based topology optimization approach to design compact wideband coaxial-to-waveguide transitions. The underlying optimization problem shows a strong self penalization towards binary solutions, which entails mesh-dependent designs that generally exhibit poor performance. To address the self penalization issue, we develop a filtering approach that consists of two phases. The first phase aims to relax the self penalization by using a sequence of linear filters. The second phase relies on nonlinear filters and aims to obtain binary solutions and to impose minimum-size control on the final design. We present results for optimizing compact transitions between a 50-Ohm coaxial cable and a standard WR90 waveguide operating in the X-band (8-12 GHz).

  • 390.
    Hedström, Simon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    General Purpose Vector Representation for Swedish Documents: An application of Neural Language Models2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis is a proof-of-concept for embedding Swedish documents using continuous vectors. These vectors can be used as input in any subsequent task and serves as an alternative to discrete bag of words vectors. The differences goes beyond fewer dimensions as the continuous vectors also hold contextual information. This means that documents with no shared vocabulary can be directly identified as contextually similar, which is impossible for the bag of words vectors. The continuous vectors are the result of neural language models and algorithms that pool the model output into document-level representations. This thesis has looked into the latest research regarding such models, starting from the Word2Vec algorithms.

    A wide variety of neural language models were selected together with algorithms for pooling word and sentence vectors into document vectors. For the training of the neural language models we have assembled a training corpus spanning 1.2 billion Swedish words. The trained neural language models were later paired with pooling algorithms to finalize an array of document vector models. The document vector models were evaluated on five classifications tasks and compared against the baseline bag of words vectors. A few models that were trained directly on the evaluation data were also included as reference. For each evaluation task the setup was held constant, which ensured that any difference in performance came from the quality of the document representations.

    The results show that the continuous document vectors outperform the baseline on topic and text format classifications tasks. It was noted that the best performance was achieved when a document vector model was trained directly on the evaluation data. However, this result was only marginally better than that of the best general document vector models. In conclusion it was a successful proof of concept but there are still improvements to be made, such as optimizing the composition of the training corpus. Due to its simplicity and overall performance we recommend a general Sent2Vec model as a new baseline for future projects.

  • 391.
    Hegner, Stephen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    A simple model of negotiation for cooperative updates on database schema components2011Inngår i: Information modelling and knowledge bases XXII / [ed] Anneli Heimbürger, Yasuni Kiyoki, Takehiro Tokuda, Hannu Jakkola, and Naofumi Yoshida, Amsterdam: IOS Press , 2011, s. 154-173Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Modern applications involving information systems often require thecooperation of several distinct users, and many models of such cooperation havearisen over the years. One way to model such situations is via a cooperative updateon a database; that is, an update for which no single user has the necessary accessrights, so that several users, each with distinct rights, must cooperate to achievethe desired goal. However, cooperative update mandates new ways of modellingand extending certain fundamentals of database systems. In this paper, such extensionsare explored, using database schema components as the underlying model.The main contribution is an effective three-stage process for inter-component negotiation.Modern applications involving information systems often require thecooperation of several distinct users, and many models of such cooperation havearisen over the years. One way to model such situations is via a cooperative updateon a database; that is, an update for which no single user has the necessary accessrights, so that several users, each with distinct rights, must cooperate to achievethe desired goal. However, cooperative update mandates new ways of modellingand extending certain fundamentals of database systems. In this paper, such extensionsare explored, using database schema components as the underlying model.The main contribution is an effective three-stage process for inter-component negotiation.

  • 392.
    Hegner, Stephen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Internal representation of database views2010Inngår i: Journal of universal computer science (Online), ISSN 0948-695X, E-ISSN 0948-6968, Vol. 16, nr 20, s. 2956-2985Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 393.
    Hegner, Stephen J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Constraint-preserving snapshot isolation2016Inngår i: Annals of Mathematics and Artificial Intelligence, ISSN 1012-2443, E-ISSN 1573-7470, Vol. 76, nr 3-4, s. 281-326Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method for detecting potential violations of integrity constraints of concurrent transactions running under snapshot isolation (SI) is presented. Although SI provides a high level of isolation, it does not, by itself, ensure that all integrity constraints are satisfied. In particular, while current implementations of SI enforce all internal integrity constraints, in particular key constraints, they fail to enforce constraints implemented via triggers. One remedy is to turn to serializable SI (SSI), in which full serializability is guaranteed. However, SSI comes at the price of either a substantial number of false positives, or else a high cost of constructing the full direct serialization graph. In this work, a compromise approach, called constraint-preserving snapshot isolation (CPSI), is developed, which while not guaranteeing full serializability, does guarantee that all constraints, including those enforced via triggers, are satisfied. In contrast to full SSI, CPSI requires testing concurrent transactions for conflict only pairwise, and thus involves substantially less overhead while providing a foundation for resolving conflicts via negotiation rather than via abort and restart. As is the case with SSI, CPSI can result in false positives. To address this, a hybrid approach is also developed which combines CPSI with a special version of SSI called CSSI, resulting in substantially fewer false positives than would occur using either approach alone.

  • 394.
    Hegner, Stephen J.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Andrea Rodriguez, M.
    A Model for Multigranular Data and Its Integrity2017Inngår i: Informatica (Vilnius), ISSN 0868-4952, E-ISSN 1822-8844, Vol. 28, nr 1, s. 45-78Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Data involving spatial and/or temporal attributes are often represented at different levels of granularity in different source schemata. In this work, a model of such multigranular data is developed, which supports not only the usual order structure on granules, but also lattice-like join and disjointness operators for relating such granules in much more complex ways. In addition, a model for multigranular thematic attributes, to which aggregation operators are applied, is provided. Finally, the notion of a thematic multigranular comparison dependency, generalizing ordinary functional and order dependencies but specifically designed to model the kinds of functional and order dependencies which arise in the multigranular context, and in particular incorporating aggregation into the definition of the constraint, is developed.

  • 395.
    Helgesson, Robert
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Generalized General Logics2013Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Logic as a vehicle for sound reason has a long and lustrous history and while most developments follow the traditional notions of binary truth and crisp sentences, great efforts have been placed into the problem of reasoning with uncertainties. To this end the field of "fuzzy logic" is now of great importance both theoretically and practically. The present monograph seeks to extend and clarify the treatment of non-classical notions of logic and, more broadly, information representation in general. This is done using two theoretical developments presented with additional discussions concerning possible applications.

    The first theoretical development takes the form of a novel and strictly categorical term monad that readily allows for a multitude of non-classical situations and extensions of the classical term concept. For example, using monad composition we may represent and perform substitutions over many-valued sets of terms and thereby represent uncertainty of information. As a complementary example, we may extend this term monad to incorporate uncertainty on the level of variables and indeed the operators themselves. These two notions are embodied inthe catchphrases "computing with fuzzy" and "fuzzy computing".

    The second theoretical development is a direct generalization of the notion of general logics, a successful categorical framework to describe and interrelate the various concepts included under theumbrella term of 'logic'. The initial leap towards general logics was the introduction of institutions by Goguen and Burstall. This construction cover the semantic aspects of logics and in particular, axiomatizes the crucial satisfaction relation. Adding structures for, e.g., syntactic entailment and proof calculi, Meseguer established general logics as a framework capable of describing a wide range of logics. We will in our generalization further extend general logics to more readily encompass non-classical notions of truth such as in fuzzy logics and logics operating over non-classical notions of sets of sentences.

  • 396.
    Hellstrand, Peter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Optimized iPhone Real-TimeRendering2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Rendering is the process of generating an image from a model. This process requires heavy computations. The iPhone has very limited hardware. The purpose of this project is to optimize the rendering process in the iPhone game "Top Gear, Stunt School" developed by Resolution Interactive AB. This thesis describes the evaluation and implementation of different optimizations used for the game.

  • 397. Hellström, Thomas
    A random walk through the stock market1998Bok (Annet vitenskapelig)
  • 398. Hellström, Thomas
    An intelligent rollator with steering by braking2012Rapport (Annet vitenskapelig)
  • 399.
    Hellström, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Kinematics Equations for Differential Drive and Articulated Steering2011Rapport (Annet vitenskapelig)
  • 400. Hellström, Thomas
    et al.
    Bensch, Suna
    Modeling Interaction for Understanding in HRI2018Inngår i: Proceedings of Explainable Robotic Systems Workshop at HRI 2018, Chicago, USA, March 2018, 2018, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    As robots become more and more capable and autonomous, there is an increased need for humans to understand what the robots do and think. In this paper we investigate what such understanding means and includes, and how robots are and can be designed to support understanding. We present a model of interaction for understanding. The aim is to provide a uniform formal understanding of the large body of existing work, and also to support continued work in the area.

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