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  • 2901.
    Tesfatsion, Selome Kostentinos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Tomás, Luis
    Red Hat, Madrid, Spain.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    OptiBook: Optimal Resource Booking for Energy-efficient Datacenters2017In: 2017 IEEE/ACM 25th International Symposium on Quality of Service (IWQoS), IEEE Communications Society, 2017Conference paper (Refereed)
    Abstract [en]

    A lack of energy proportionality, low resource utilization, and interference in virtualized infrastructure make the cloud a challenging target environment for improving energy efficiency. In this paper we present OptiBook, a system that improves energy proportionality and/or resource utilization to optimize performance and energy efficiency. OptiBook shares servers between latency-sensitive services and batch jobs, over- books the system in a controllable manner, uses vertical (CPU and DVFS) scaling for prioritized virtual machines, and applies performance isolation techniques such as CPU pinning and quota enforcement as well as online resource tuning to effectively improve energy efficiency. Our evaluations show that on average, OptiBook improves performance per watt by 20% and reduces energy consumption by 9% while minimizing SLO violations. 

  • 2902.
    Tesfatsion, Selome Kostentinos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Wadbro, Eddie
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    PerfGreen: Performance and Energy Aware Resource Provisioning for Heterogeneous Clouds2018Manuscript (preprint) (Other academic)
    Abstract [en]

    Improving energy efficiency in a cloud environment is challenging because of

    poor energy proportionality, low resource utilization, interference as well as workload,

    application, and hardware dynamism. In this paper we present PerfGreen,

    a dynamic auto-tuning resource management system for improving energy efficiency

    with minimal performance impact in heterogeneous clouds. PerfGreen

    achieves this through a combination of admission control, scheduling, and online

    resource allocation methods with performance isolation and application priority

    techniques. Scheduling in PerfGreen is energy aware and power management capabilities

    such as CPU frequency adaptation and hard CPU power limiting are

    exploited. CPU scaling is combined with performance isolation techniques, including

    CPU pinning and quota enforcement, for prioritized virtual machines to

    improve energy efficiency. An evaluation based on our prototype implementation

    shows that PerfGreen with its energy-aware scheduler and resource allocator on

    average reduces energy usage by 53%, improves performance per watt by 64%

    and server density by 25% while keeping performance deviations to a minimum.

  • 2903.
    Teveldal, Adam
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Larsson, Kennie
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Lago, Mikael
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Effektiviteten av en handbok för EnScript2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With the increase in IT related crimes the IT forensics has more work ahead of them and it is constantly rising. The analysis software called EnCase is widely used by IT forensics all around the globe and with it comes an internal programming language called EnScript.

    This paper is designed to examine whether a manual for the programming language EnScript can make a difference in how efficiently the work is.A study between two groups has been made and an evaluation of the results between the two groups.

    The manual provided aims to introduce the reader to EnScript as a programming language and also to provide a solid foundation to build on in further work with EnScript

  • 2904.
    Thekkilakattil, Abhilash
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Davis, Rob
    University of York, UK.
    Dobrin, Radu
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Punnekkat, Sasikumar
    Birla Institute of Technology and Science, India.
    Bertogna, Marko
    University of Modena, Italy.
    Multiprocessor Fixed Priority Scheduling with Limited Preemptions2015In: ACM International Conference Proceeding Series, Volume 04-06, 2015, p. 13-22Conference paper (Refereed)
    Abstract [en]

    Challenges associated with allowing preemptions and migrations are compounded in multicore systems, particularly under global scheduling policies, because of the potentially high overheads. For example, multiple levels of cache greatly increase preemption and migration related overheads as well as the difficulty involved in accurately accounting for them, leading to substantially inflated worst-case execution times. Preemption and migrations related overheads can be significantly reduced, both in number and in size, by using fixed preemption points in the tasks' code; thus dividing each task into a series of non-preemptive regions. This leads to an additional consideration in the scheduling policy. When a high priority task is released and all of the processors are executing non-preemptive regions of lower priority tasks, then there is a choice to be made in terms of how to manage the next preemption. With an eager approach the first lower priority task to reach a preemption point is preempted even if it is not the lowest priority running task. Alternatively, with a lazy approach, preemption is delayed until the lowest priority currently running task reaches its next preemption point. In this paper, we show that under global fixed priority scheduling with eager preemptions each task suffers from at most a single priority inversion each time it resumes execution. Building on this observation, we derive a new response time based schedulability test for tasks with fixed preemption points. Experimental evaluations show that global fixed priority scheduling with eager preemptions is significantly more effective than with lazy preemption using link based scheduling in terms of task set schedulability.

  • 2905.
    Thekkilakattil, Abhilash
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Dobrin, Radu
    Mälardalen University, School of Innovation, Design and Engineering.
    Punnekkat, Sasikumar
    Mälardalen University, School of Innovation, Design and Engineering.
    Preemption Control using CPU Frequency Scaling in Real-time Systems2011In: 18th INTERNATIONAL CONFERENCE ON CONTROL SYSTEMS AND COMPUTER SCIENCE, 2011, p. 88-95Conference paper (Refereed)
    Abstract [en]

    Controlling the preemption behavior in real-time systems can have beneficial impacts in multiple contexts as it can decrease the processor utilization, reduce the energy consumption or even enable the schedulability of the system. In this paper we study the preemption behavior of sporadic task systems scheduled using the Fixed Priority Scheduling (FPS) policy, and evaluate the feasibility of preemption control using CPU frequency scaling. We show that offline preemption control using CPU frequency scaling is difficult for sporadic task systems, and we propose an online heuristic algorithm, of linear complexity, to control the number of preemptions in a sporadic task system. Evaluation results show that online CPU frequency scaling is an attractive approach for preemption control in sporadic task systems.

  • 2906.
    Thekkilakattil, Abhilash
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Dodig-Crnkovic, Gordana
    Chalmers Technical University and University of Gothenburg, Gothenburg, Sweden.
    Ethics Aspects Of Embedded And Cyber-Physical Systems2015In: 2015 IEEE 39th Annual Computer Software and Applications Conference (COMPSAC), 2015, p. 39-44Conference paper (Refereed)
    Abstract [en]

    The growing complexity of software employed in the cyber-physical domain is calling for a thorough study of both its functional and extra-functional properties. Ethical aspects are among important extra-functional properties, that cover the whole life cycle with different stages from design, development, deployment/production to use of cyber physical systems. One of the ethical challenges involved is the question of identifying the responsibilities of each stakeholder associated with the development and use of a cyber-physical system. This challenge is made even more pressing by the introduction of autonomous increasingly intelligent systems that can perform functionalities without human intervention, because of the lack of experience, best practices and policies for such technology. In this article, we provide a framework for responsibility attribution based on the amount of autonomy and automation involved in AI based cyber-physical systems. Our approach enables traceability of anomalous behaviors back to the responsible agents, be they human or software, allowing us to identify and separate the "responsibility" of the decision-making software from human responsibility. This provides us with a framework to accommodate the ethical "responsibility" of the software for AI based cyber-physical systems that will be deployed in the future, underscoring the role of ethics as an important extra-functional property. Finally, this systematic approach makes apparent the need for rigorous communication protocols between different actors associated with the development and operation of cyber-physical systems that further identifies the ethical challenges involved in the form of group responsibilities.

  • 2907.
    Thiele, Bernhard
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pop, Adrian
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Flattening of Modelica State Machines: a practical symbolic representation2015In: Proceedings of the 11th International Modelica Conference: Versailles, France, September 21-23, 2015 / [ed] Peter Fritzson, Hilding Elmqvist, Linköping: Linköping University Electronic Press, 2015, p. 255-263Conference paper (Refereed)
    Abstract [en]

    Modelica 3.3 introduced dedicated built-in language support for state machines that was inspired by semantics known from Statechart and mode automata formalisms. The specification describes the semantics of these constructs in terms of data-flow equations that allows to relate it to the Modelica DAE representation which is the conceptual intermediate format of Modelica code after instance creation (flattening). However, a complete transformation of state machine constructs into data-flow equations at the stage of flattening requires an early commitment to implementation details that potentially hinders model optimizations at subsequent translation phases. Also, due to the required substantial model transformation the semantic distance between the original source model and the flattened representation is rather large. Hence, this paper proposes a more versatile symbolic representation for flattened state machine constructs that preserves the state machine’s composition structure and allows postponing optimizations to subsequent compiler phases.

  • 2908.
    Tholander, Oscar
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    System design for integration of faultisolation and recording tool for airplanes.2013Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the possibilities to design enterprise software after the REST architectural style and also look into how these kinds of systems can be developed using the .NET 4.0 Framework, Windows Communication Foundation (WCF) and EntityFramework 4.0. The thesis will in detail go through how to design the database abstraction to transferring the database content over a network, encoded with JSON to a client. The proposed solution is a viable way of designing network based software and is quite simple to implement when you get you head around the concepts of REST. The future in developing REST based applications is getting better and easier in the .NET Framework with added and improved support for in newer releases of the framework.

  • 2909.
    Thoman, Peter
    et al.
    Univ Innsbruck, A-6020 Innsbruck, Austria..
    Dichev, Kiril
    Queens Univ Belfast, Belfast BT7 1NN, Antrim, North Ireland..
    Heller, Thomas
    Univ Erlangen Nurnberg, D-91058 Erlangen, Germany..
    Iakymchuk, Roman
    KTH.
    Aguilar, Xavier
    KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Hasanov, Khalid
    IBM Ireland, Dublin 15, Ireland..
    Gschwandtner, Philipp
    Univ Innsbruck, A-6020 Innsbruck, Austria..
    Lemarinier, Pierre
    IBM Ireland, Dublin 15, Ireland..
    Markidis, Stefano
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH Royal Inst Technol, S-10044 Stockholm, Sweden..
    Jordan, Herbert
    Univ Innsbruck, A-6020 Innsbruck, Austria..
    Fahringer, Thomas
    Univ Innsbruck, A-6020 Innsbruck, Austria..
    Katrinis, Kostas
    IBM Ireland, Dublin 15, Ireland..
    Laure, Erwin
    KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Nikolopoulos, Dimitrios S.
    Queens Univ Belfast, Belfast BT7 1NN, Antrim, North Ireland..
    A taxonomy of task-based parallel programming technologies for high-performance computing2018In: Journal of Supercomputing, ISSN 0920-8542, E-ISSN 1573-0484, Vol. 74, no 4, p. 1422-1434Article in journal (Refereed)
    Abstract [en]

    Task-based programming models for shared memory-such as Cilk Plus and OpenMP 3-are well established and documented. However, with the increase in parallel, many-core, and heterogeneous systems, a number of research-driven projects have developed more diversified task-based support, employing various programming and runtime features. Unfortunately, despite the fact that dozens of different task-based systems exist today and are actively used for parallel and high-performance computing (HPC), no comprehensive overview or classification of task-based technologies for HPC exists. In this paper, we provide an initial task-focused taxonomy for HPC technologies, which covers both programming interfaces and runtime mechanisms. We demonstrate the usefulness of our taxonomy by classifying state-of-the-art task-based environments in use today.

  • 2910.
    Thomas, Ilias
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Optimizing levodopa dosing routines for Parkinson’s disease2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis in the field of microdata analysis aims to introduce dose optimizing algorithms for the pharmacological management of Parkinson’s disease (PD). PD is a neurodegenerative disease that mostly affects the motor functions of the patients and it is characterized as a movement disorder. The core symptoms of PD are: bradykinesia, postural instability, rigidity, and tremor. There is no cure for PD and the use of levodopa to manage the core symptoms is considered the gold standard. However, long term use of levodopa causes reduced medication efficacy, and side effects, such as dyskinesia, which can also be attributed to overmedication. When that happens precise individualized dosing schedules are required. The goal of this thesis is to examine if algorithmic methods can be used to find dosing schedules that treat PD symptoms and minimize manifestation of side effects. Data from three different sources were used for that purpose: data from a clinical study in Uppsala University hospital in 2015, patient admission chart data from Uppsala University hospital during 2011-2015, and data from a clinical study in Gothenburg University during 2016-2017. The data were used to develop the methods and evaluate the performance of the proposed algorithms.The first algorithm that was developed was a sensor-based method that derives objective measurements (ratings) of PD motor states. The construction of the sensor index was based on subjective ratings of patients’ motor functions made by three movement disorder experts. This sensor-based method was used when deriving algorithmic dosing schedules. Afterwards, a method that uses medication information and ratings of the patients’ motor states to fit individual patient models was developed. This method uses mathematical optimization to individualize specific parameters of dose-effects models for levodopa intake, through minimizing the distance between motor state ratings and dose-effect curves. Finally, two different dose optimization algorithms were developed and evaluated, that had as input the individual patient models. The first algorithm was specific to continuous infusion of levodopa treatment, where the patient’s state was set to a specific target value and the algorithm made dosing adjustments to keep that patients motor functions on that state. The second algorithm concerned oral administration of microtables of levodopa. The ambition with this algorithm was that the suggested doses would find the right balance between treating the core symptoms of PD and, at the same time, minimizing the side effects of long term levodopa use, mainly dyskinesia. Motor state ratings for this study were obtained through the sensor index. Both algorithms followed a principle of deriving a morning dose and a maintenance dose for the patients, with maintenance dose being an infusion rate for the first algorithm, and oral administration doses at specific time points for the second algorithm.The results showed that the sensor-based index had good test-retest reliability, sensitivity to levodopa treatment, and ability to make predictions in unseen parts of the dataset. The dosing algorithm for continuous infusion of levodopa had a good ability to suggest an optimal infusion rating for the patients, but consistently suggested lower morning dose than what the treating personnel prescribed. The dosing algorithm for oral administration of levodopa showed great agreement with the treating personnel’s prescriptions, both in terms of morning and maintenance dose. Moreover, when evaluating the oral medication algorithm, it was clear that the sensor index ratings could be used for building patient specific models.

  • 2911.
    Thomke, Sven
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Implementation av Microsoft Exchange ActiveSync mot en molntjänst2013Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This report describes a bachelor thesis work performed at the cloud storage company CloudMe in Linköping, Sweden. The storage service provided by CloudMe allows users to access their files seamlessly from multiple units at the same time. In the cloud there is storage provided for contacts, calendar and e-mail, which is data nowadays normally used by smart phones.Exchange ActiveSync is a protocol developed by Microsoft which, among much more, provides functionality to synchronize the previously described data. This protocol is supported by the smart phone developers and the ability to synchronize over the exchange protocol is implemented in products by default. Due to this fact it would be preferable to implement support for synchronization from CloudMe to phones over this protocol. Therefore a decision was made to create a proxy server which handles communication with clients (smart phones) over Exchange ActiveSync and talks with CloudMes SOAP-based open API to extract the needed data. With the help of this server a user would be able to synchronize the described data between different phones and tablets, independently of label and model and would never have to worry about loss of data.The purpose of this bachelor thesis work was therefore to design and implement such a proxy server, so that clients would be able to connect, through the standard support for exchange in smart phones,and synchronize data between phones and the cloud. The report describes the methods used when designing the project and also the problems that occurred during the process.

  • 2912.
    Thorslund, Birgitta
    et al.
    Linköping University, The Swedish Institute for Disability Research. Linköping University, Department of Behavioural Sciences and Learning. Linköping University, Faculty of Arts and Sciences.
    Peters, Björn
    Linköping University, The Swedish Institute for Disability Research. VTI, Linköping.
    Jansson, Jonas
    VTI, Linköping.
    Principle Other Vehicle Warning - POVW: En simulatorstudie för utvärdering av automatiserad ljud- och ljusvarning från mötande fordon2012Conference paper (Other academic)
    Abstract [en]

    A simulator study of a critical frontal collision situation was conducted in order to examine usefulness of different warning modalities from a principal other vehicle (POV). In total, 48 participants drove 30 km while performing a secondary task, announced by a vibration in the seat, and experiencing light and/or sound warnings from oncoming traffic.

    For comparison field measurements of light and horn sound levels were collected. The measurements were used for the implementations in the simulators graphics- and sound system respectively.

    The study aims at providing basic understanding of driver responses to headlight and sound warning coming from another vehicle. A possible application is the implementation of systems for automatic activation of these warnings. Systems for automatic activation of brakes and steering are currently entering the market. These systems use proximity sensors to monitor the state of surrounding road users. Depending on the specific situation the effort/possibility to avoid or mitigate an accident may differ significantly between the principle road users of a pending collision, e.g. one road user (1) may easily avoid a collision while another (2) may not be able to do so. The only possibility for the second road user (2) to avoid a collision in such a situation is to issue a warning to the first (1), so that he/she may take evasive actions. Connecting the horn and the headlight to already existing sensor system, for automatic warning activation, is a cost effective means to provide such a warning. These types of warnings, could of course, also be triggered manually by the driver. The aim of this project is to evaluate the effectiveness of such a warning and also to validate if the warning between the road users is experienced as intended and whether the warning is an effective countermeasure for avoiding accidents.

    There is limited research on how to design warning signals to avoid collision. In a simulator study auditory collision warnings with increasing intensity have been shown more effective than other types of auditory warnings (Gray, 2011). According to research regarding warning signals in general, auditory warnings should, if possible impart the nature of the events to the user. (Edworthy, 1995a). Research have also shown that people can match the frequency with which they respond to alarms to the false alarm rate, that increasing the perceived urgency of an alarm decreases reaction time and that increasing the number of modalities in which a warning is presented decreases reaction time. (Edworthy, 1995b)

     

    Another objective of this study was to develop simulation technology for a realistic sensation of headlight glare and horn sound of an oncoming vehicle. The effect of using these signaling systems in a critical situation was then studied in the VTI simulator III (Nordmark, Jansson, Palmkvist, & Sehammar, 2004). The aim of the present study was to find a suitable warning signal, triggered by a first vehicle, which makes the driver of a second vehicle react fast enough to avoid a collision. It is important that the driver understands the message of the signal to be able to distinguish between “normal” horn and blink signals which are not time critical and this time critical warning. An additional cognitive task was used to distract the drivers to create a critical event.

    The driving scenario was a rural road (70 kph speed limit) where the driver of a vehicle was distracted by means of a visual distraction task (reading and recalling letters from a screen placed at a relative large down angle (40-45 degrees), and then “pushed” across the median towards an oncoming vehicle, by introducing a steering angle in the simulated vehicle without submitting that information to the motion platform. The oncoming vehicle detects that the situation is critical and attempts to use headlight glare and horn sound to warn the driver of the vehicle that is drifting into oncoming traffic.

    A within person design with four experimental warning conditions were used to evaluate the modality of the warning signals. Non critical noise and light signals from POV represented for example a greeting or a wish to make the driver aware of the headlight. The purpose of the non-critical signals was to evaluate if the driver understands the difference between the critical and non-critical signal. Measurements used to monitor driver behavior were lateral distance between the vehicles when passing, and driver reaction time (in term of steering wheel and brake pedal response). This was accompanied with subjective ratings during and after the test drive, both to evaluate the realism of the simulated event and the usefulness of the warning provided by the meeting vehicle.

    The participants drove the Subject Vehicle (SV) with the instruction to drive as he or she usually does. In total, the participant experienced the critical event 5 times during this trip. Three different warning signals were presented, one at each event. The warning coming from the encountering vehicle was given through an automatic system triggering the horn and/or the lights of the POV. There was also a baseline event when no warning was given. The warning signals was presented in balanced order to avoid effects of which signal is presented first etc. The signal presented at the first event was also presented at the fifth event. This was to be able to investigate the learning effect. The non-critical noise and light signals were presented in the gaps between two warning signals.

    The analysis is in process and will be completed in time for the full length paper submission. Preliminary results from the questionnaire show that participants have noticed the following warnings during the drive; sound (n=44), light (n=39), sound and light (n=32). Most participants think that the warnings were useful (n=31). Sound and vibration in the simulator is thought to be realistic. Participants are very positive to the announcement of the secondary task through a vibration in the seat. Most participants are positive to all three warning types; light (n=36), sound (n=31), light and sound (n=41).

  • 2913.
    Thümmler, Christoph
    et al.
    Technical University Munich, Munich, Geremany.
    Keow Lim, A.
    Celestor Ltd, UK.
    Holanec, Ivo
    Institute and Faculty of Actuaries, Edinburgh, UK.
    Fricker, Samuel
    Blekinge Institute of Technology, Faculty of Computing, Department of Software Engineering.
    A Methodology to Assess Social Technological Alignment in the Health Domain2016In: Innovation and Research in BioMedical Engineering, ISSN 1959-0318, Vol. 37, no 4, p. 232-239Article in journal (Refereed)
    Abstract [en]

    There have been longstanding discussions whether social or technological factors eventually determine the speed of innovation, in particular when it comes to implementation. In order to identify and quantify potential resistance and implementation risks in the health domain we propose a set of key parameters, which are measurable in both – the social and the technological dimensions. Following a meta-analysis we identified the following parameters to be of relevance: readiness, shared values, motivation, elasticity, control and time. All these parameters are scalable and measurable in both dimensions with existing tools. Mapping and comparison of the social and technological dimensions of these parameters might allow conclusions on how far the social and technological dimensions of these parameters are aligned and where potential difficulties during the implementation have to be expected. (This paper refers to the technical term “implementation” as the process of integrating a new technology into established workflows).

  • 2914.
    Tim, Andersson
    Linköping University, Department of Computer and Information Science, Database and information techniques.
    Result size calculation for Facebook's GraphQL query language2018Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    GraphQL is a query language for web APIs and a service for carrying out server requeststo interact with the data from the API. Research show that even for simple GraphQL queriesboth the size of the response object and the execution times to retrieve these objects may beprohibitively large and that current implementations of the language suffers from this issue.This thesis explores the implementation of an algorithm for calculating the exact size of theresponse object from a GraphQL query, and the performance based evaluation of the implementation. A proof of concept of a server using the implementation of the algorithm and subsequent tests of thecalculation times for particularly problematic queries sent to the server, show that the implementationscales well and could serve as a way to stop these queries from executing.

  • 2915.
    Timliden, Erik
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Domain-Specific Language data- validation and manipulation in a case handlingsystem2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This thesis creates a Domain-Specific Languages (DSL) implementation and integration inside the iipax case handling software. The implementation investigated advantages with Domain-Specific Languages. Following agile software development methods the paper results in a functioning Domain-Specific Language emulating written English.

  • 2916.
    Tingvall, Jesper
    Linköping University, Department of Electrical Engineering, Information Coding.
    Interior Design and Navigation in Virtual Reality2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis examined how virtual reality could be used in interior design. The thesis was limited to virtual reality experienced using a head mounted display. The Method was to integrate virtual reality into an existing interior design software called CET Designer. After investigating the available commercial virtual reality hardware and software Oculus SDK and OpenVR was chosen. Unity 3D was used as a prototyping tool for experimenting with different interaction and navigation methods. An user study with 14 participants was performed. It compared four different navigation methods. First person shooter style controls using a gamepad was proven to be the best one. It can also be concluded that having a bad navigation style could decreased the user experience in virtual reality and cause motion sickness.

  • 2917.
    Tiwari, Saurabh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. DA-IICT, Gandhinagar, India.
    Ameta, D.
    DA-IICT, Gandhinagar, India.
    Singh, P.
    NIT Jalandhar, India.
    Sureka, A.
    Ashoka University, India.
    Teaching requirements engineering concepts using case-based learning2018In: Proceedings - International Conference on Software Engineering, 2018, Vol. F138007, p. 8-15Conference paper (Refereed)
    Abstract [en]

    Requirements Engineering (RE) is known to be critical for the success of software projects, and hence forms an important part of any Software Engineering (SE) education curriculum offered at tertiary level. In this paper, we report the results of an exploratory pilot study conducted to assess the effectiveness of Case-Based Learning (CBL) methodology in facilitating the learning of several RE concepts. The evaluation was made on the basis of graduate students' responses to a set of questions representing various key learning principles, collected after the execution of two CBL sessions at DA-IICT, Gandhinagar (India). We investigate the perceived effectiveness of CBL in students' learning of various RE concepts, based on factors like case difference, gender diversity, and team size. Additionally, we collect and analyze the Teaching Assistants' (TAs) opinions about the conducted CBL sessions. The outcome of this CBL exercise was positive as maximum students were able to achieve all the five stated learning objectives. The authors also report various challenges, recommendations, and lessons learned while experiencing CBL sessions. 

  • 2918.
    Tjøstheim, Ingvar
    et al.
    Norsk Regnesentral.
    Leister, Wolfgang
    Norsk Regnesentral.
    Mork, Heidi
    Norsk Regnesentral.
    Fritsch, Lothar
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science.
    Research Directions for Studying Users’ Privacy Awareness2016Report (Other academic)
    Abstract [en]

    In this document, we present a set of research questions on how to evoke reflection about

    sharing of personal data and privacy. We look into analytical approaches to understand

    the phenomenon of people’s privacy behaviour and into synthetical approaches to let

    the user practise privacy skills to increase awareness using visualisation and simulation

    technologies in scenarios of relevance to the user. We also review potential risks to security,

    privacy, anonymity, and other assets and the use of information in social media, for

    advertisement and commercial activities.

  • 2919.
    Tobias, Eklund
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Informatics and Media.
    Spehar, Joakim
    CPlanner: Kursplaneringsprototyp med Design Science och Scrum2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Development of planning system is a complex design problem that requires both a high degree of flexibility but also structure. In the context of planning, there are several actors, activities and resources that must be considered. Expertise in planning is often concentrated in a few key individuals. It is therefore no coincidence that many businesses, organizations and even universities currently conducts its planning in proven single-user system like Excel even though there is a strong need for standardized multi-user system. Uppsala University is no exception, despite its size, with over 40,000 students, 6,200 employees, 130 programs and 2000 courses. Course planning is conducted using single-user system and which is dependent on a number of key individuals to plan to work. The essay aims to investigate and illustrate the problems that are associated with the development of the planning system by developing a prototype of a course scheduling system. The research strategy used is Design Science and the development methodology that is used is Scrum. The prototype has been evaluated regularly during development through formative evaluation. The essays knowledge contribution is methodological knowledge that shows both how Scrum and Design Science can be combined and model knowledge, which shows the basic structure of a course scheduling system.

  • 2920.
    Tomas, Luis
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Caminero, Blanca
    University of Castilla-La Mancha.
    Carrión, Carmen
    University of Castilla-La Mancha.
    Opportunistic Energy-Aware Rescheduling in Desktop Grid Environments2013In: 2013 International Conference on High Performance Computing & Simulation (HPCS2013), 2013, p. 178-185Conference paper (Refereed)
    Abstract [en]

    Nowadays either maximizing energy efficiency andimproving resource utilization is a challenge among the differentexisting distributed systems, specially in large scale distributedenvironments such as Grids or Clouds. With this objective, wepropose a rescheduling technique that tries to improve resourceusage, whilst at the same time tries to minimize the energy neededfor the executions of the already accepted jobs by using first/morethe resources that are more energy efficient and without reducingthe QoS provided. The information obtained from a devicecapable of measuring the energy that each desktop resourceneeds is used by the algorithm at the resource selection process,resulting in a noticeable reduction in the energy used as it hasbeen demonstrated in a real desktop Grid environment.

  • 2921.
    Tomas, Luis
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Cloudy with a Chance of Load Spikes: Admission Control with Fuzzy Risk Assessments2013In: 6th IEEE International Conference on Utility and Cloud Computing, 2013, p. 155-162Conference paper (Refereed)
    Abstract [en]

    Elasticity is key for the cloud paradigm, wherethe pay-per use nature provides great flexibility for end-users.However, elasticity complicates long-term capacity planning forcloud providers as the exact amount of resources requiredover time becomes uncertain. Admission control techniques arethus needed to handle the trade-off between resource utilizationand potential overload. We define a set of admission controlalgorithms that combine risk assessment methods with a fuzzyaggregation framework. An experimental evaluation using amixture of bursty and steady applications demonstrate that ouralgorithms can increase resource utilization by a factor of twowhile limiting overload problems to a few percent.

  • 2922.
    Tomas, Luis
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Improving Cloud Infrastructure Utilization through Overbooking2013In: Proceedings of the 2013 ACM Cloud and Autonomic Computing Conference, 2013Conference paper (Refereed)
    Abstract [en]

    Despite the potential given by the combination of multitenancyand virtualization, resource utilization in today’sdata centers is still low. We identify three key characteristicsof cloud services and infrastructure as-a-service managementpractices: burstiness in service workloads, fluctuationsin virtual machine resource usage over time, and virtual machinesbeing limited to pre-defined sizes only. Based on thesecharacteristics, we propose scheduling and admission controlalgorithms that incorporate resource overbooking to improveutilization. A combination of modeling, monitoring, andprediction techniques is used to avoid overpassing the totalinfrastructure capacity. A performance evaluation using amixture of workload traces demonstrates the potential forsignificant improvements in resource utilization while stillavoiding overpassing the total capacity.

  • 2923.
    Tomasic, Ivan
    et al.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Rashkovska, Aleksandra
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Depolli, Matjaž
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Using Hadoop MapReduce in a multicluster environment2013In: The 36th international convention on information and communication technology, electronics and microelectronics MIPRO 2013, 2013, Vol. Article number 6596280, p. 369-374Conference paper (Refereed)
    Abstract [en]

    Hadoop MapReduce has become one of the most popular tools for data processing. Hadoop is normally installed on a cluster of computers. When the cluster becomes undersized, it can be scaled by adding new computers and storage devices, but it can also be extended by real or virtual resources from another computer cluster. We present a utilization of the MapReduce paradigm on a Hadoop installation extended across two clusters connected over the Internet. We measured execution times of Map and Reduce tasks in a multicluster environment, and compared them to the corresponding times obtained while only computers from a single cluster are used. The results show that there might be a decrease inMapReduce performance depending on: the concrete data analyses application, the ratio of the number of local and remote computers, and connection bandwidth to remote computers. Additionally, the investigation suggests an upgrade to the Apache Hadoop MapReduce, making it more adjusted to the multicluster environment.

  • 2924.
    Torra, Vicenc
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Transparency and Disclosure Risk in Data Privacy2015In: Proceedings of the Workshops of the EDBT/ICDT 2015 Joint Conference (EDBT/ICDT) / [ed] Peter M. Fischer, Gustavo Alonso, Marcelo Arenas, Floris Geerts, 2015, p. 246-Conference paper (Other academic)
    Abstract [en]

    k-Anonymity and differential privacy can be considered examples of Boolean definitions of disclosure risk. In contrast, record linkage and uniqueness are examples of quantitative measures of risk. Record linkage is a powerful approach because it can model different types of scenarios in which an adversary attacks a protected database with some information and background knowledge. Transparency holds in data privacy when data is published together with details on their processing. This includes the data protection method used and its parameters. Intruders can use this information to improve their attacks. Specific record linkage algorithms can be defined to take into account this information, and to define more accurate disclosure risk measures. Machine learning and optimization techniques also permits us to increase the  effectiveness of record linkage algorithms. This talk will be focused on disclosure risk measures based on record linkage. We will describe how we can improve the performance of the algorithms under the transparency principle, as well as using machine learning and optimization techniques.

  • 2925.
    Torra, Vicenç
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    A fuzzy microaggregation algorithm using fuzzy c-means2015In: Artificial Intelligence Research and Development / [ed] Eva Armengol, Dionís Boixader, Francisco Grimaldo, IOS Press, 2015, p. 214-223Conference paper (Refereed)
    Abstract [en]

    Masking methods are used in data privacy to avoid the disclosure of sensitive information. Microaggregation is a perturbative masking method that has been proven effective. Data masked using microaggregation can be attacked when the intruder has information of the masking method and the parameters used. Publishing this information is usual under the transparency principle. Fuzzy microaggregation was introduced a few years ago to avoid this type of transparency attacks. In this paper we propose a new simpler method for microaggregation based on fuzzy c-means. We discuss the effectiveness of the approach. One of the advantages of this approach is its computational complexity.

  • 2926.
    Torra, Vicenç
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Derivation of Priorities and Weights for Set-Valued Matrices Using the Geometric Mean Approach2015In: Applied Artificial Intelligence, ISSN 0883-9514, E-ISSN 1087-6545, Vol. 29, no 5, p. 500-513Article in journal (Refereed)
    Abstract [en]

    Priorities are essential in the analytic hierarchy process (AHP). Several approaches have been proposed to derive priorities in the framework of the AHP. Priorities correspond to the weights in the weighted mean as well as in other aggregation operators as the ordered weighted averaging (OWA) operators, and the quasi-arithmetic means.

    Derivation of priorities for the AHP typically starts by eliciting a preference matrix from an expert and then using this matrix to obtain the vector priorities. For consistent matrices, the vector of priorities is unique. Nevertheless, it is usual that the matrix is not consistent. In this case, different methods exist for extracting this vector from the matrix.

    This article introduces a method for this purpose when the cells of the matrix are not a single value but a set of values. That is, we have a set-valued preference matrix. We discuss the relation of this type of matrices and hesitant fuzzy preference relations.

  • 2927.
    Torra, Vicenç
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    On the selection of m for Fuzzy c-Means2015In: Proceedings of the 2015 Conference of the International Fuzzy Systems Association and the European Society for Fuzzy Logic and Technology / [ed] José M. Alonso, Humberto Bustince & Marek Reformat, Paris: Atlantis Press , 2015, p. 1571-1577Conference paper (Refereed)
    Abstract [en]

    Fuzzy c-means is a well known fuzzy clustering algorithm. It is an unsupervised clustering algorithmthat permits us to build a fuzzy partition from data. The algorithm depends on a parameter m whichcorresponds to the degree of fuzziness of the solution. Large values of m will blur the classes andall elements tend to belong to all clusters. The solutionsof the optimization problem depend on theparameter m. That is, different selections of m willtypically lead to different partitions. In this paper we study and compare the effect ofthe selection of m obtained from the fuzzy c-means.

  • 2928.
    Torra, Vicenç
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Guillen, Montserrat
    Department of Econometrics, Riskcenter-IREA, University of Barcelona, Spain.
    Santolino, Miguel
    Department of Econometrics, Riskcenter-IREA, University of Barcelona, Spain.
    Continuous m-dimensional distorted probabilities2018In: Information Fusion, ISSN 1566-2535, E-ISSN 1872-6305, Vol. 44, p. 97-102Article in journal (Refereed)
  • 2929.
    Torra, Vicenç
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Narukawa, Yasuo
    Distances on non-additive measures using the numerical Choquet integrale2015In: The 12th International Conference on Modeling Decisions for Artificial Intelligence: CD-ROM Proceedings, MDAI - HiS , 2015Conference paper (Refereed)
  • 2930.
    Torra, Vicenç
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Narukawa, YasuoToho Gakuen, Tokyo, Japan.
    Modeling Decisions for Artificial Intelligence: 12th International Conference, MDAI 2015, Skövde, Sweden, September 21-23, 2015, Proceedings2015Conference proceedings (editor) (Refereed)
  • 2931.
    Torra, Vicenç
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Narukawa, Yasuo
    Toho Gakuen, Naka, Kunitachi, Tokyo, Japan.
    Numerical integration for the Choquet integral2016In: Information Fusion, ISSN 1566-2535, E-ISSN 1872-6305, Vol. 31, p. 137-145Article in journal (Refereed)
    Abstract [en]

    Choquet integrals with respect to non-additive (or fuzzy measures) have been used in a large number of applications because they permit us to integrate information from different sources when there are interactions. Successful applications use a discrete reference set. In the case of measures on a continuous reference set, as e.g. the real line, few results have been obtained that permit us to have an analytical expression of the integral. However, in most of the cases there is no such analytical expression. In this paper we describe how to perform the numerical integration of a Choquet integral with respect to a non-additive measure.

  • 2932.
    Torra, Vicenç
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Narukawa, YasuoDahlbom, AndersUniversity of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    The 12th International Conference on Modeling Decisions for Artificial Intelligence: CD-ROM Proceedings2015Conference proceedings (editor) (Refereed)
  • 2933.
    Torra, Vicenç
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre. IIIA-CSIC, Campus UAB s/n, Bellaterra, Catalonia, Spain.
    Narukawa, Yasuo
    Toho Gakuen, Kunitachi, Tokyo, Japan.
    Sugeno, Michio
    ECSC, c/ Gonzalo Gutiérrez Quirós s/n, Mieres, Spain.
    On the f-divergence for non-additive measures2016In: Fuzzy sets and systems (Print), ISSN 0165-0114, E-ISSN 1872-6801, Vol. 292, p. 364-379Article in journal (Refereed)
    Abstract [en]

    The f -divergence evaluates the dissimilarity between two probability distributions defined in terms of the Radon–Nikodym derivative of these two probabilities. The f -divergence generalizes the Hellinger distance and the Kullback–Leibler divergence among other divergence functions. In this paper we define an analogous function for non-additive measures. We discuss them for distorted Lebesgue measures and give examples. Examples focus on the Hellinger distance.

  • 2934.
    Tosteberg, Joakim
    et al.
    Linköping University, Department of Electrical Engineering, Computer Engineering. Linköping University, The Institute of Technology.
    Axelsson, Thomas
    Linköping University, Department of Electrical Engineering, Computer Engineering. Linköping University, The Institute of Technology.
    Development of a Wireless Video Transfer System for Remote Control of a Lightweight UAV2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A team of developers from Epsilon AB has developed a lightweight remote controlledquadcopter named Crazyflie. The team wants to allow a pilot to navigate thequadcopter using video from an on-board camera as the only guidance. The masterthesis evaluates the feasibility of mounting a camera module on the quadcopter andstreaming images from the camera to a computer, using the existing quadcopterradio link. Using theoretical calculations and measurements, a set of requirementsthat must be fulfilled for such a system are identified. Using the requirementsas a basis, various camera products are investigated and the findings presented.A design to fulfill the requirements, using the found products, is proposed. Theproposed design is then implemented and evaluated.

    It is found that the Crazyflie system has the resources necessary to transferan image stream with the quality required for navigation. Furthermore, theimplementation is found to provide the required functionality. From the evaluationseveral key factors of the design that can be changed to further improve theperformance of an implementation are identified. Ideas for future work andimprovements are proposed and possible alternative approaches are presented.

  • 2935.
    Toufanpanah, Monir
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Decision Support framework: Reliable Federated Single Sign-on2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Identity management is a critical concept for enterprises, and it has turned to more challenging issue since businesses are significantly moving towards service oriented architecture (SOA) with the aim to provide seamless service delivery to their customers, partners and employees. The organizational domains are expanded to blur the virtual borders, simplify the business collaboration and maximize opportunities in the competitive market place, which explicitly shows the essentiality for federating the identities. Real-world identity comprises of different dimensions such as Law, Business, Policy, Technology and Society, therefore reliable digital identity management and successful federation are required to take these dimensions and complexity into consideration.

    Considering variety of academic and industrial researches that report on remarkable demands for identity federation adoption by enterprises, this study has approached federated Identity Management from technological point of view. Technologies provide tools and mechanisms to satisfy the business requirements and enable single sign-on capability in reliable federated platform.

    Different authentication technologies and standards have emerged to enable federated single sign-on (FSSO) implementation as a core service of the FIdM, each with different features and capabilities. This brings more complexity and confusion for experts and decision makers for FIdM adoption and development. To overcome this obstacle and accelerate the data collection and analysis process for decision makers, this research contributes to the filed by providing a conceptual framework to simplify the analysis of underlying technology for decision making process. In this framework 1) a list of state-of-the-art requirements and mechanisms for successful identity federation and reliable SSO is elaborated, 2) Six most prevalent standard authentication technologies along with latest specifications are analysed, explained and assessed against the defined criteria, and 3) several security and privacy consideration are gathered. The usage of framework is monitored and the efficiency of it is evaluated in 2 real business case scenarios by five IT experts and the result is reported.

  • 2936.
    Trabasso, Luís Gonzaga
    et al.
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering. Aeronautics Institute of Technology, Dept. of Mechanical Engineering .
    Alfredson, Jens
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering. SAAB, Aeronautics Human Machine Interaction, Sweden.
    Functional Mapping as Means for Establishing a Human Factors Research Environment for Future Air Systems2016In: Proceedings of the 12th Swecog Cognition Conference, October 6-7, Göteborg, Sweden: Abstracts / [ed] Alexander Almér, Robert Lowe and Erik Billing, Skövde: Univeristy of Skövde , 2016, Vol. 1, p. 10-11Conference paper (Other academic)
    Abstract [en]

    A typical environment for human factors research has equipment and methods for performing a set of experiments such as mental workload assessment, situational awareness evaluation, human resilience measurement and so forth. The common aspect between equipment and methods is that they accomplish a function. The TLX method is part of such an environment because it evaluates the mental workload; an EEG helmet is part of the same research environment because it measures the electrical activity originated by the brain. If the functional structure of a method or equipment is yet to be known, a method for function deployment might be used to this purpose such as FAST. Although cognitive processes in many regards are very different from functions in technical systems, it is possible to describe them in terms of functions for the sake using it for design considerations. For instance, the information-processing paradigm has inspired descriptions that in some regards could be described in functional terms. The multiple resource theory that outlines different mental resources related to various modalities and stages of processing is another example of that. Then a functional mapping engine identifies the equipment and method that address the cognitive functions required for a given experiment. A very simple example of functional mapping is as follows: the cognitive module <vision> has a function X {to track objects}. The equipment *eye tracker* and the method # EPOG – Eye Point of Gaze# have the functions Y [To look at through computer vision] and Z [to track objects]. The mapping among functions X, Y and Z indicate the equipment and method are suitable for addressing the cognitive characteristic under investigation. On the one hand, if an equipment or method do exist, then the functional mapping assist the research environment designer to identify them and help choosing if several options are available. On the other hand, if an equipment or method do not exist, then the functional mapping assist the research environment designer to design and build them. Moving forward from the very simple example to a more practical and realistic situation, the functional mapping can tackle the issues of choosing the necessary functions – from both sides, cognitive and equipment and methods – to meet fidelity requirements of an experiment. This is suggested to be resolved by the cost-benefit trade-off approach detailed as follows. Based on the functional mapping, selective fidelity can be obtained for modeling and simulation considerations. Thereby advantages and disadvantages of the human factors research environment for future air systems could be balanced by the functional mapping, potentially optimizing the use of simulations. System border definition ought to be considered; the border definition practice borrowed from aircraft product/system configuration can be used to this end. Selective fidelity has been applied to transfer of training in military aviation and simulator based design has been shown to be useful for development of air systems. The proposed functional mapping approach could have the potential of adding to this tradition.

  • 2937.
    Tran, Dung Duc
    et al.
    Duy Tan University Danang, Vietnam.
    Tran, Ha-Vu
    University of Quebec, Montreal, Canada.
    Ha, Dac-Binh
    Duy Tan University Danang, Vietnam.
    Hung, Tran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Kaddoum, Gorge
    University of Quebec, Montreal, Canada.
    Performance Analysis of Two-Way Relaying System with Radio Frequency Energy Harvesting and Multiple Antennas2016In: 84th IEEE Vehicular Technology Conference IEEE VTC 2016, Quebec city, Canada, 2016Conference paper (Refereed)
  • 2938.
    Tran, Ha-Vu
    et al.
    University of Quebec, Montreal, Canada.
    Kaddoum, Gorge
    University of Quebec, Montreal, Canada.
    Hung, Tran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tran, Dung Duc
    Duy Tan University, Danang, Vietnam.
    Ha, Dac-Binh
    Duy Tan University, Danang, Vietnam.
    Time Reversal SWIPT Networks with an Active Eavesdropper: SER-Energy Region Analysis2017In: 84th IEEE Vehicular Technology Conference IEEE VTC 2016, Quebec city, Canada, 2017Conference paper (Refereed)
    Abstract [en]

    This paper analyzes a novel multiple-input single-output (MISO) simultaneous wireless information and power transfer (SWIPT) system model in the presence of an active eavesdropper over the frequency-selective fading channel. In this model, a transmitter applies the time reversal (TR) beamforming technique to combat the fading effects whereas a legitimate user employs a power splitter to jointly receive information and energy, and the active eavesdropper jams the user. Given the system model, the system performance in terms of symbol error rate (SER) and energy harvesting (EH) is analyzed. In particular, we devise a SER-energy region, instead of the conventional rate-energy region, to evaluate system performance of the SWIPT model. A moment generating function (MGF)-based method is presented to exactly derive the average SER analysis. Moreover, the closed-form expression of average effective harvested energy is then provided to complete SER-energy region analysis. Finally, analytical results confirmed by numerical simulations show that the TR technique can support the SWIPT system to notably improve the SER performance whereas the jamming signal can enhance the EH performance.

  • 2939.
    Tran, Hung Vinh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Zepernick, H. -J
    Blekinge Institute of Technology, Sweden.
    Phan, H.
    University of Reading, United Kingdom .
    On throughput and quality of experience in cognitive radio networks2016In: IEEE Wireless Communications and Networking Conference, WCNC, 2016, article id 7564784Conference paper (Refereed)
    Abstract [en]

    In this paper, a performance analysis for cognitive radio networks (CRNs) under the outage probability constraint of the primary user and peak transmit power constraint of the secondary user is conducted. Given an automatic repeat request protocol, analytical expressions for the packet delay and throughput of the CRN are derived. Most importantly, these expressions can be used to understand the quality of experience on web services which are assumed to be offered by the considered CRN.

  • 2940.
    Tran, Hung
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Zepernick, H. -J
    Blekinge Institute of Technology, Karlskrona, Sweden.
    Proactive attack: A strategy for legitimate eavesdropping2016In: 2016 IEEE 6th International Conference on Communications and Electronics, IEEE ICCE 2016, 2016, p. 457-461Conference paper (Refereed)
    Abstract [en]

    In this paper, we study a novel approach to eavesdrop the messages of suspicious users for a surveillance purpose. In particular, we consider a scenario in which the legitimate monitor can act as a jamming source and a decode-And-forward relay station that can force the suspicious users to reveal their exchanged messages. Accordingly, the power allocation policies for the jamming signal of the legitimate monitor subject to deterministic and non-deterministic interference channels are considered. On this basis, we derive a closed-form expression for the successful eavesdropping probability to evaluate the system performance. More importantly, our results reveal that the successful eavesdropping probability of the non-deterministic interference channel from the legitimate monitor to the suspicious receiver outperforms the one of the deterministic interference channel. 

  • 2941.
    Trianti, Alexandra
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Implementing New Generation Catalog in an Academic Library: Users’ Views and Wishes2015Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    In an accelerating Information and Communication Technologies (ICTs) environment, academic libraries’ catalogs have always been part of students’ and faculty members journey of resources discovery. The master thesis intents to focus its interest in Information Systems (IS) ground related to the implementation of a new search engine at the University of Piraeus Library.

    The Library wants to change the search features of its traditional online services and to implement a new discover tool with Web 2.0 characteristics. The aim of this master thesis is to investigate users’ views and desires interest according to their scholarly needs and expectations about VuFind in order to facilitate the Library to customize the integration. Therefore, critical systems theory will be employed for “therapeutic” reasons to enlighten the Library’s users about their current situation.

    Qualitative analysis is expected to recognize discrimination against traditional Library’s search engines. Qualitative data of the user impression and reaction when operate with the VuFind interface will lead to recommendations for enhancement and improvements. Findings will assist implementers to modify the discovery layer by meeting users’ needs of the academia community. The research will collect data through qualitative method on how participants operate with the VuFind search engine merging librarians’ professional views and users’ expectations and propositions. Participatory Design (PD) will be built upon Future Workshop method.

  • 2942.
    Trichon, Vincent
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL.
    A Singing Drone Choir2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Drones have a new emerging use case: performing in shows and live events. This master thesis has been driven by an artistic project invited to take part in a full-scale operatic performance in the Croatian National Theatre Ivan Zajc in Rijeka, Croatia, in 2019. This project merges technological research with ancient theatrical and operatic traditions by using drones as an opera choir. After describing the process of designing and building a fleet of quadrotors equipped with speakers, we present a reacting and interacting motion planning strategy based on potential fields. We analyse and evaluate our drone design with its control strategy on simulation and on a real drone.

  • 2943.
    Trigo Algar, Antonio Rafael
    University of Skövde, School of Humanities and Informatics.
    Serious Games For Overcoming Phobias: The Benefits of Game Elements2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis analyses the benefits of applying game elements to a Virtual Reality application for overcoming phobias, with a special focus on acrophobia, i.e. the fear of heights. Two different prototypes using the Oculus Rift head-mounted display were developed with a gradually exposure to heights. Both prototypes shared the same acrophobic scenario, but one included extra features from games such as engagement, motivation or goals. Twenty-four participants, divided into two groups of twelve, with moderate aversion to heights tested the prototypes. The participants’ heart rate and the time that they looked down from high altitudes were also measured and evaluated. The study showed slightly higher results regarding motivation for the prototype which included the additional game elements. Future studies should include a different head-mounted display, which would allow a longer time of play without motion sickness, and the participation of people diagnosed with acrophobia.

  • 2944.
    Trinh, Lan Anh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Cürüklü, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Fault Tolerance Analysis for Dependable Autonomous Agents Using Colored Time Petri Nets2017In: ICAART: PROCEEDINGS OF THE 9TH INTERNATIONAL CONFERENCE ON AGENTS AND ARTIFICIAL INTELLIGENCE, VOL 1, 2017, p. 228-235Conference paper (Refereed)
    Abstract [en]

    Fault tolerance has become more and more important in the development of autonomous systems with the aim to help the system to recover its normal activities even when some failures happen. Yet, one of the concerns is how to analyze the reliability of a fault tolerance mechanism with regards to the collaboration of multiple agents to complete a complicated task. To do so, an approach of fault tolerance analysis with the colored time Petri net framework is proposed in this work, where a task can be represented by a tree of different concurrent and dependent subtasks to assign to agents. Different subtasks and agents are modeled by color tokens in Petri network. The time values are added to evaluate the processing performance of the whole system with respect to its ability to solve a task with fault tolerance ability. The colored time Petri nets are then tested with simulation of centralized and distributed systems. Finally the experiments are performed to show the feasibility of the proposed approach. From the basics of this study, a generalized framework in the future can be developed to address the fault tolerance analysis for a set of agents working with a sophisticated plan to achieve a common target.

  • 2945.
    Trinh, LanAnh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Dependability for Autonomous Control with a Probability Approach2017In: ERCIM News, ISSN 0926-4981, E-ISSN 1564-0094, no 109, p. 22-23Article in journal (Other academic)
    Abstract [en]

    For the last decade, dependability - the ability to offer a service that can be trusted - has been the focus of much research, and is of particular interest when designing and building systems. We are developing a dependable framework for an autonomous system and its control.

  • 2946.
    Trinh, LanAnh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Dipole Flow Field for Dependable Path Planning of Multiple Agents2017In: IEEE/RSJ International Conference on Intelligent Robots and Systems IROS, 2017Conference paper (Refereed)
  • 2947.
    Trinh, LanAnh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Toward Shared Working Space of Human and Robotic Agents Through Dipole Flow Field for Dependable Path Planning2018In: Frontiers in Neurorobotics, ISSN 1662-5218, Vol. 12, article id 28Article in journal (Refereed)
    Abstract [en]

    Recent industrial developments in autonomous systems, or agents, which assume that humans and the agents share the same space or even work in close proximity, open for new challenges in robotics, especially in motion planning and control. In these settings, the control system should be able to provide these agents a reliable path following control when they are working in a group or in collaboration with one or several humans in complex and dynamic environments. In such scenarios, these agents are not only moving to reach their goals, i.e., locations, they are also aware of the movements of other entities to find a collision-free path. Thus, this paper proposes a dependable, i.e, safe, reliable and effective, path planning algorithm for a group of agents that share their working space with humans. Firstly, the method employs the Theta* algorithm to initialize the paths from a starting point to a goal for a set of agents. As Theta* algorithm is computationally heavy, it only reruns when there is a significant change of the environment. To deal with the movements of the agents, a static flow field along the configured path is defined. This field is used by the agents to navigate and reach their goals even if the planned trajectories are changed. Secondly, a dipole field is calculated to avoid the collision of agents with other agents and human subjects. In this approach, each agent is assumed to be a source of a magnetic dipole field in which the magnetic moment is aligned with the moving direction of the agent. The magnetic dipole-dipole interactions between these agents generate repulsive forces to help them to avoid collision. The effectiveness of the proposed approach has been evaluated with extensive simulations. The results show that the static flow field is able to drive agents to the goals with a small number of requirements to update the path of agents. Meanwhile, the dipole flow field plays an important role to prevent collisions. The combination of these two fields results in a safe path planning algorithm, with a deterministic outcome, to navigate agents to their desired goals.

  • 2948.
    Trunfio, Paolo
    et al.
    DEIS, University of Calabria, Via Pietro Bucci 41C, 87036 Rende (CS), Italy.
    Talia, Domenico
    DEIS, University of Calabria, Via Pietro Bucci 41C, 87036 Rende (CS), Italy.
    Papadakis, Harris
    Institute of Computer Science, Foundation for Research and Technology-Hellas, P.O. Box 1385, 71 110 Heraklion-Crete, Greece.
    Fragopoulou, Paraskevi
    Institute of Computer Science, Foundation for Research and Technology-Hellas, P.O. Box 1385, 71 110 Heraklion-Crete, Greece.
    Mordacchini, Matteo
    Universit`a Ca Foscari di Venezia and INFN Sezione di Padova, Italy.
    Pennanen, Mika
    VTT Information Technology Tietoverkot, P.O. Box 1203 FIN-02044, Finland.
    Popov, Konstantin
    Swedish Institute of Computer Science, Box 1263, SE-164 29 Kista, Sweden.
    Vlassov, Vladimir
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Haridi, Seif
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Peer-to-Peer resource discovery in Grids: Models and systems2007In: Future generations computer systems, ISSN 0167-739X, E-ISSN 1872-7115, Vol. 23, no 7, p. 864-878Article in journal (Refereed)
    Abstract [en]

    Resource location or discovery is a key issue for Grid systems in which applications are composed of hardware and software resources that need to be located. Classical approaches to Grid resource location are either centralized or hierarchical and will prove inefficient as the scale of Grid systems rapidly increases. On the other hand, the Peer-to-Peer (P2P) paradigm emerged as a Successful model that achieves scalability in distributed systems. One possibility would be to borrow existing methods from the P2P paradigm and to adopt them to Grid systems taking into consideration the existing differences. Several such attempts have been made during the last couple of years. This paper aims to serve as a review of the most promising Grid systems that use P2P techniques to facilitate resource discovery in order to perform a qualitative comparison of the existing approaches and to draw conclusions about their advantages and weaknesses. Future research directions are also discussed.

  • 2949.
    Tsog, Nandinbaatar
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Becker, Matthias
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Larsson, Marcus
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Bruhn, Fredrik
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Sjödin, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Malardalen Univ, Sch Innovat Design & Engn, DPAC Res Profile, Vasteras, Sweden..
    Poster Abstract: Real-Time Capabilities of HSA Compliant COTS Platforms2016In: PROCEEDINGS OF 2016 IEEE REAL-TIME SYSTEMS SYMPOSIUM (RTSS), 2016, p. 364-364Conference paper (Refereed)
    Abstract [en]

    During recent years, the interest in using heterogeneous computing architecture in industrial applications has increased dramatically. These architectures provide the computational power that makes them attractive for many industrial applications. However, most of these existing heterogeneous architectures suffer from the following limitations: difficulties of heterogeneous parallel programming and high communication cost between the computing units. To overcome these disadvantages, several leading hardware manufacturers have formed the HSA Foundation to develop a new hardware architecture: Heterogeneous System Architecture (HSA). In this paper, we investigate the suitability of using HSA for real-time embedded systems. A preliminary experimental study has been conducted to measure massive computing power and timing predictability of HSA.

  • 2950.
    Tsog, Nandinbaatar
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Becker, Matthias
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Larsson, Marcus
    Bruhn, Fredrik
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Sjödin, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Real-Time Capabilities of HSA Compliant COTS Platforms2016In: 37th IEEE Real-Time Systems Symposium Work-in-Progress (WiP) session RTSS'16, 2016, article id 7809871Conference paper (Refereed)
    Abstract [en]

    During recent years, the interest in using heterogeneous computing architecture in industrial applications has increased dramatically. These architectures provide the computational power that makes them attractive for many industrial applications. However, most of these existing heterogeneous architectures suffer from the following limitations: difficulties of heterogeneous parallel programming and high communication cost between the computing units. To overcome these disadvantages, several leading hardware manufacturers have formed the HSA Foundation to develop a new hardware architecture: Heterogeneous System Architecture (HSA). In this paper, we investigate the suitability of using HSA for real-time embedded systems. A preliminary experimental study has been conducted to measure massive computing power and timing predictability of HSA.

56575859606162 2901 - 2950 of 3259
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