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  • 251. Order onlineBuy this publication >>
    Andersson, Dennis
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Mission Experience: How to Model and Capture it to Enable Vicarious Learning2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Organizations for humanitarian assistance, disaster response and military activities are characterized by their special role in society to resolve time-constrained and potentially life-threatening situations. The tactical missions that these organizations conduct regularly are significantly dynamic in character, and sometimes impossible to fully comprehend and predict. In these situations, when control becomes opportunistic, the organizations are forced to rely on the collective experience of their personnel to respond effectively to the unfolding threats. Generating such experience through traditional means of training, exercising and apprenticeship, is expensive, time-consuming, and difficult to manage.

    This thesis explores how and why mission experience should be utilized in emergency management and military organizations to improve performance. A multimedia approach for capturing mission experience has further been tested in two case studies to determine how the commanders’ experiences can be externalized to enable vicarious learning. These studies propose a set of technical, methodological, and ethical issues that need to be considered when externalizing mission experience, based on two aforementioned case studies complemented by a literature review. The presented outcomes are (1) a model aligning abilities that tactical organizations need when responding to dynamic situations of different familiarity, (2) a review of the usefulness of several different data sources for externalization of commanders’ experiences from tactical operations, and (3) a review of methodological, technical, and ethical issues to consider when externalizing tactical military and emergency management operations. The results presented in this thesis indicate that multimedia approaches for capturing mission histories can indeed complement training and exercising as a method for generating valuable experience from tactical missions.

    List of papers
    1. Sharing Mission Experience in Tactical Organisations
    Open this publication in new window or tab >>Sharing Mission Experience in Tactical Organisations
    2012 (English)In: ISCRAM 2012 Conference Proceedings. Book of Papers. 9th International Conference on Information Systems for Crisis Response and Management / [ed] Leon Rothkrantz, Jozef Ristvej and Zeno Franco, ISCRAM , 2012Conference paper, Published paper (Refereed)
    Abstract [en]

    A tactical organisation can be seen as an adhocracy designed to perform missions in uncertain, ambiguous and complex environments. Flexibility, adaptability, resilience, innovation, creativity and improvisation have all been identified as key skills for successful outcome of these missions. To learn skills associated with such abilities previous research has shown that knowledge acquired through experience plays an important role. It is therefore important that individuals, teams and organisations share and learn from experiences to improve their ability to cope with novel situations. In literature there is a lack of consistency in how these abilities are discussed, we therefore propose the FAIRIC model to help define and differentiate between the concepts. By unravelling some of the similarities and differences we create a common vocabulary to discuss knowledge gained from experience. This can help classify different experiences and provide a more systematic way of gathering knowledge on situational factors that influence the success of different actions and more unified interpretations that can assist design of knowledge representations to share mission experience over boundaries of time and space.

    Place, publisher, year, edition, pages
    ISCRAM, 2012
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-91985 (URN)978-0-86491-332-6 (ISBN)
    Conference
    The 9th International ISCRAM Conference on Information Systems for Crisis Response and Management, April 22-25, Vancouver, Canada
    Available from: 2013-05-07 Created: 2013-05-07 Last updated: 2013-05-07Bibliographically approved
    2. Evaluation of Crisis Management Operations using Reconstruction and Exploration
    Open this publication in new window or tab >>Evaluation of Crisis Management Operations using Reconstruction and Exploration
    2008 (English)In: Proceedings of the 5th International ISCRAM Conference, Washington, DC: May 4-7 / [ed] Frank Fiedrich and Bartel Van de Walle, ISCRAM , 2008, p. 118-125Conference paper, Published paper (Refereed)
    Abstract [en]

    In this paper we present the Reconstruction and Exploration approach (R&E) and F-REX tool and their applications in a field exercise with the Swedish Rescue Services Agency with the purpose of investigating features needed for a computer supported approach for evaluation of large scale crisis management operations. After the exercise several interviews and one seminar were held to evaluate R&E as a representative for computer supported evaluation approaches for crisis management operations. Initial results indicate that multimedia presentation of key events from an operation can be very valuable not only to stimulate the participants to reflect on their own performance, but also to document and share lessons learned to non-participants.

    Place, publisher, year, edition, pages
    ISCRAM, 2008
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-91986 (URN)978-0-615-20697-4 (ISBN)
    Conference
    ISCRAM2008 - Creating Advanced Systems for Inter-organizational Information Sharing and Collaboration, Washington, DC, USA, May 4-7, 2008
    Available from: 2013-05-07 Created: 2013-05-07 Last updated: 2015-08-19Bibliographically approved
    3. Reconstruction and Exploration of Large-scale Distributed Operations – Multimedia tools for Evaluation of Emergency Management Response
    Open this publication in new window or tab >>Reconstruction and Exploration of Large-scale Distributed Operations – Multimedia tools for Evaluation of Emergency Management Response
    2008 (English)In: Journal of Emergency Management, ISSN 1543-5865, Vol. 6, no 4, p. 31-47Article in journal (Refereed) Published
    Abstract [en]

    This study presents an approach for computer-supported reconstruction and exploration (R&E) of distributed tactical operations. The approach involves several steps for constructing a time-synchronized, event-driven multimedia model of the course of events collected from multiple sources in the operational environment and visualizes this model in the F-REX Studio multimedia suite. In this study, the use of R&E and F-REX is explored in large-scale emergency management exercises. The approach’s possibilities, limitations, and needs for modification are first outlined followed by a comparison to traditional quantitative and qualitative data collection methods applied in the same context. It is found that the R&E approach in combination with F-REX has several advantages in relation to the other methods, in terms of avoiding problems of retrospection and in being able to provide an overview of the entire operation based on multiple perspectives—addressing the question “why” something happened rather than “what happened.” Correctly used, multimedia-supported R&E can thereby be used for more solid evaluations of large-scale emergency management exercises and operations, thus contributing to more effective handling of future crises. Keywords: reconstruction & exploration, distributed tactical operations, emergency management, evaluation, computer technology

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-91987 (URN)
    Available from: 2013-05-07 Created: 2013-05-07 Last updated: 2017-12-06Bibliographically approved
    4. Privacy and Distributed Tactical Operations Evaluation
    Open this publication in new window or tab >>Privacy and Distributed Tactical Operations Evaluation
    2011 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    In this study, thoughts on ethics of workplace monitoring are being applied to the very special domain of evaluations of tactical operations, such as military or crisis management exercises or operations. I try to find out if there are differences in the way we should regard workplace monitoring when it comes to this domain compared to standard workplaces such as offices, since the purpose of the surveillance is not to enforce discipline, but to evaluate the organizations’ ability to conduct a tactical operation. The study focuses on issues such as privacy and informed consent and the main purpose of the investigation is to structure a consistent ethical standpoint when it comes to operations’ evaluation by making parallels to related theories that I found correct and applicable. I conclude that is indeed reasonable to place other demands on crisis management workers than we would do on other work forces, and that it should therefore be easier to motivate workplace monitoring for the purpose of evaluating distributed tactical operations. I argue however, just as Miller does regarding police work, that upholding privacy can be a real problem when crisis management personnel are exposed to monitoring, even though it is intended for evaluation.

    Place, publisher, year, edition, pages
    CENTRIC, 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-91988 (URN)978-1-61208-167-0 (ISBN)
    Conference
    The Fourth International Conference on Advances in Human-oriented and Personalized Mechanisms, Technologies, and Services, CENTRIC 2011, October 23-29, 2011, Barcelona, Spain
    Available from: 2013-05-07 Created: 2013-05-07 Last updated: 2013-05-07Bibliographically approved
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    Mission Experience: How to Model and Capture it to Enable Vicarious Learning
    Download (pdf)
    omslag
  • 252.
    Andersson, Dennis
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Privacy and Distributed Tactical Operations Evaluation2011Conference paper (Refereed)
    Abstract [en]

    In this study, thoughts on ethics of workplace monitoring are being applied to the very special domain of evaluations of tactical operations, such as military or crisis management exercises or operations. I try to find out if there are differences in the way we should regard workplace monitoring when it comes to this domain compared to standard workplaces such as offices, since the purpose of the surveillance is not to enforce discipline, but to evaluate the organizations’ ability to conduct a tactical operation. The study focuses on issues such as privacy and informed consent and the main purpose of the investigation is to structure a consistent ethical standpoint when it comes to operations’ evaluation by making parallels to related theories that I found correct and applicable. I conclude that is indeed reasonable to place other demands on crisis management workers than we would do on other work forces, and that it should therefore be easier to motivate workplace monitoring for the purpose of evaluating distributed tactical operations. I argue however, just as Miller does regarding police work, that upholding privacy can be a real problem when crisis management personnel are exposed to monitoring, even though it is intended for evaluation.

  • 253.
    Andersson, Dennis
    et al.
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Pilemalm, Sofie
    Linköping University, Department of Management and Engineering, Information Systems. Linköping University, The Institute of Technology.
    Hallberg, Niklas
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Evaluation of Crisis Management Operations using Reconstruction and Exploration2008In: Proceedings of the 5th International ISCRAM Conference, Washington, DC: May 4-7 / [ed] Frank Fiedrich and Bartel Van de Walle, ISCRAM , 2008, p. 118-125Conference paper (Refereed)
    Abstract [en]

    In this paper we present the Reconstruction and Exploration approach (R&E) and F-REX tool and their applications in a field exercise with the Swedish Rescue Services Agency with the purpose of investigating features needed for a computer supported approach for evaluation of large scale crisis management operations. After the exercise several interviews and one seminar were held to evaluate R&E as a representative for computer supported evaluation approaches for crisis management operations. Initial results indicate that multimedia presentation of key events from an operation can be very valuable not only to stimulate the participants to reflect on their own performance, but also to document and share lessons learned to non-participants.

  • 254.
    Andersson, Dennis
    et al.
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Rankin, Amy
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Sharing Mission Experience in Tactical Organisations2012In: ISCRAM 2012 Conference Proceedings. Book of Papers. 9th International Conference on Information Systems for Crisis Response and Management / [ed] Leon Rothkrantz, Jozef Ristvej and Zeno Franco, ISCRAM , 2012Conference paper (Refereed)
    Abstract [en]

    A tactical organisation can be seen as an adhocracy designed to perform missions in uncertain, ambiguous and complex environments. Flexibility, adaptability, resilience, innovation, creativity and improvisation have all been identified as key skills for successful outcome of these missions. To learn skills associated with such abilities previous research has shown that knowledge acquired through experience plays an important role. It is therefore important that individuals, teams and organisations share and learn from experiences to improve their ability to cope with novel situations. In literature there is a lack of consistency in how these abilities are discussed, we therefore propose the FAIRIC model to help define and differentiate between the concepts. By unravelling some of the similarities and differences we create a common vocabulary to discuss knowledge gained from experience. This can help classify different experiences and provide a more systematic way of gathering knowledge on situational factors that influence the success of different actions and more unified interpretations that can assist design of knowledge representations to share mission experience over boundaries of time and space.

  • 255.
    Andersson, Dennis
    et al.
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology. Swedish Def Research Agency, Linkoping, Sweden.
    Rankin, Amy
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Arts and Sciences.
    Diptee, Darryl
    Naval Postgrad Sch, USA.
    Approaches to team performance assessment: a comparison of self-assessment reports and behavioral observer scales2017In: Cognition, Technology & Work, ISSN 1435-5558, E-ISSN 1435-5566, Vol. 19, no 2-3, p. 517-528Article in journal (Refereed)
    Abstract [en]

    Human factors research popularly employs perception-based techniques to investigate team performance and its dependency to cognitive processes. Such studies frequently rely upon either observer-based or self-assessment techniques to collect data. In this study, we examined behavioral observer ratings and self-assessment ratings for measuring team performance in virtual teams, with team performance regarded as a combination of task outcome and team cognition. Juxtaposing self-assessments and observer ratings from a quasi-experiment comparing team performance rating techniques reveals that they indeed produce overall similar results, with both singling out teamwork effectiveness ratings as the strongest contributor to overall team performance. However, the comparisons show remarkably low correlation on individual questionnaire items. The most striking difference is that the team members self-assessments of workload are lower than the corresponding observer ratings. In particular, the self-assessments do not correlate at all with overall team performance, whereas the observers workload ratings are more consistent with contemporary research that suggests a strong correlation between workload and team performance, suggesting that observer-based techniques are more reliable than self-assessments for assessing workload. For other ratings, the results show that the two techniques are fairly equal, suggesting that the choice between methods to employ can be deferred to other considerations such as obtrusiveness, accessibility, and resource availability.

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    fulltext
  • 256.
    Andersson, Ellen
    Linköping University, Department of Computer and Information Science.
    Cognitive Workload, Game Experience, and Intrinsic Motivation2017Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    When it comes to game design, two features that have been linked to the success of a game are playability and the subjective game experience. This is perhaps not surprising, as the main purpose of a game is to entertain. What cognitive factors that may underlie these features has, however, not been explored. This study examines the relationship between both workload and cognitive workload and player experience. The results suggest that an increase in workload, including cognitive workload, positively affect the player experience of the game as well as the player’s intrinsic motivation.

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    fulltext
  • 257.
    Andersson, Erik
    et al.
    Linköping University, Department of Computer and Information Science.
    Combler, David
    Linköping University, Department of Computer and Information Science.
    Evaluation of Key Management Protocols and Their Implementations2018Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    When constructing a network system it is important to consider the attributes which define said system and how to best build around those attributes. In this report we’ve studied Key Management Protocols as well as 802.15.4 WPAN networks and how key managment is conducted in such networks. This was done to better understand how Key Management Protocols themselves work and if, or how, they differ when used in 802.15.4 networks.

    In this report we studied 4 different Key Management Protocols: IKEv2,HIPv2,PANA and 802.1X as well as their various implementations. Based on the information gathered we analyzed how an implementation would work according to IEEE 802.15.9.

    Firstly we found was that IKEv2 offers a lot of functionality at the cost of system complexity and required a lot of memory. It also required major modifications to work in 802.15.4 networks.

    Secondly we found that HIPv2 offers the ability to separate the locator and identifier tags of TCP/IP and is lightweight. It doesn’t use IP or TCP/UDP and as such required minor changes to work in 802.15.4 networks.

    Finally, PANA and 802.1X both offer client-to-network authentication using EAP and use a moderate to high amount of space. 802.1X required a moderate amount of changes to work in 802.15.4 networks. PANA on the other hand required few changes, though it should not be used as a general purpose Key Management Protocol in 802.15.4 networks.

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  • 258.
    Andersson, Erik Olov Mårten
    Linköping University, Department of Computer and Information Science.
    A Gameful Quest to Make Second Language Acquisition Fun2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study explores the application of principles from game design, and the motivational psychology it is founded upon, to the domain of second language acquisition. A gameful design process based on playtesting andanalysis with design lenses is adapted and used to iteratively design and develop a system for conversation practice with the goal of creating a motivating and engaging experience.The results indicate effectiveness of the process, but generalizing the results would require further research with bigger sample sizes and studies with varied core activities.

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    fulltext
  • 259.
    Andersson, Filip
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Fault Diagnosis in Distributed Simulation Systems over Wide Area Networks using Active Probing2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The domain of distributed simulation is growing rapidly. This growth leads to larger and more complex supporting network architectures with high requirements on availability and reliability. For this purpose, efficient fault-monitoring is required. This work is an attempt to evaluate the viability of an Active probing approach in a distributed simulation system in a wide area network setting. In addition, some effort was directed towards building the probing-software with future extensions in mind. The Active probing approach was implemented and tested against certain performance requirements in a simulated environment. It was concluded that the approach is viable for detecting the health of the network components. However, additional research is required to draw a conclusion about the viability in more complicated scenarios that depend on more than the responsiveness of the nodes. The extensibility of the implemented software was evaluated with the QMOOD-metric and not deemed particularly extensible.

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    fulltext
  • 260.
    Andersson, Filip
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    GPGPU-Sim2014Independent thesis Basic level (university diploma), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This thesis studies the impact of hardware features of graphics cards on performance of GPU computing using GPGPU-Sim simulation software tool. GPU computing is a growing topic in the world of computing, and could be an important milestone for computers. Therefore, such a study that seeks to identify the performance bottlenecks of the program with respect to hardware parameters of the devvice can be considered an important step towards tuning devices for higher efficiency.

    In this work we selected convolution algorithm - a typical GPGPU application - and conducted several tests to study different performance parameters. These tests were performed on two simulated graphics cards (NVIDIA GTX480, NVIDIA Tesla C2050), which are supported by GPGPU-Sim. By changing the hardware parameters of graphics card such as memory cache sizes, frequency and the number of cores, we can make a fine-grained analysis on the effect of these parameters on the performance of the program.

    A graphics card working on a picture convolution task releis on the L1 cache but has the worst performance with a small shared memory. Using this simulator to run performance tests on a theoretical GPU architecture could lead to better GPU design for embedded systems.

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  • 261.
    Andersson, Fredrik
    Linköping University, Department of Computer and Information Science.
    Genrer som stöd vid design av IT-artefakter: Reflektioner på ett designfall2002Independent thesis Advanced level (degree of Magister)Student thesis
    Abstract [sv]

    Uppsatsen ämnar svara på en övergripande frågeställning som lyder: På vilket sätt kan genrer fungera som ett stöd vid design av IT-artefakter? Detta är uppdelat i två syften. Det ena är att utreda om ett medvetet arbete med genrer kan stödja designprocessen vid design av IT-artefakter. För att svara på detta görs en genomgång om vad litteraturen säger om genrer och sedan testas detta på ett designfall som genomförs på en handdatorapplikation, närmare bestämt ett mobilt säljstöd. Det andra syftet är att vid förberedande och genomförande av detta designfall samla ihop och sammanställa designråd lämpade för handdatorer. På samma sätt som en författare av en bok kan dra nytta av genren inom vilken denne skriver borde en designer kunna göra detsamma. Flera möjliga fördelar kan ses med ett explicit genretänkande. Man skulle bland annat kunna förhindra övergeneralisering och dra nytta av förväntningar som finns hos konsumenter av den aktuella genren. Ävenkonsumenten skulle kunna dra nytta av en genreindelning om den designade artefakten förmedlade vilken genre den tillhör. Trots att arbetet med genrer benämns som en metod i uppsatsen så är det osäkert om den kan betraktas som en sådan. Man skulle kunna kalla det för ett genreperspektiv på design och kontextuellt utforskande. Även om inte enbart fördelar kan ses med genrer så verkar det som om genretänkandet förser designern med ett bra sätt att snabbt rama in situationen för vilken denne skall designa. Frågorna i genreanalysen som användes täcker upp mycket av bruket utan att fastna i detaljer.

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    FULLTEXT01
  • 262.
    Andersson, Fredrik
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Storing and structuring big data with businessintelligence in mind2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sectra has a customer database with approximately 1600 customers across the world. In this system there exists not only medical information but alsoinformation about the environment which the system runs in, usage  pattern and much more.

    This report is about storing data received from log les into a suitable database. Sectra wants to be able to analyze this information so that they can make strategic decisions and get a better understanding of their customers' needs. The tested databases are MongoDB, Cassandra, and MySQL. The results shows that MySQL  is not suitable for storing large amount of data with the current conguration. On the other hand, both MongoDB and Cassandra performed well with the growing amount of data.

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  • 263.
    Andersson Granberg, Tobias
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Stenberg, Rebecca
    Linköping University, Department of Management and Engineering, Business Administration. Linköping University, Faculty of Arts and Sciences.
    Johansson, Lars
    Linköping University, Department of Management and Engineering. Linköping University, Faculty of Arts and Sciences.
    Bång, Magnus
    Linköping University, Department of Computer and Information Science, MDALAB - Human Computer Interfaces. Linköping University, The Institute of Technology.
    Kaspersson, Thomas
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Arts and Sciences.
    Jonsson, Sandra
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Arts and Sciences.
    Nilsson, Lisa
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Arts and Sciences.
    Tåla: Trygghetsskapande åtgärder för landsbygden2010Report (Other academic)
    Abstract [sv]

    I april 2010 gav regeringen i uppdrag till Myndigheten för samhällsskydd och beredskap (MSB) att i ett projekt öka säkerheten på landsbygden genom nya former för räddning och respons. Inom ramen för ovanstående uppdrag, vilket benämns ”Samhällsviktig samverkan i landsbygd” har CARER – Centrum för respons- och räddningssystem – vid Linköpings universitet fått i uppdrag av MSB att inventera vilka behov och resurser för säkerhet och trygghet som existerar på lands- och glesbygd, samt undersöka vilka andra projekt och initiativ som föregått detta, nationellt och internationellt. CARERs projekt, som görs inom ramen för regeringsuppdraget, benämns Trygghetshöjande åtgärder för landsbygden (TÅLA).

    TÅLA har genomförts som fyra sammanhängande delstudier där de två första delstudierna använder kvalitativ metodik, främst intervjuer, och syftar till att skapa en förståelse för den upplevda tryggheten på lands- och glesbygden, samt utröna vad den består i och hur den kan stärkas. Delstudie 3 syftar till att kvantitativt uttrycka behov och resurser för säkerhet och trygghet på landsoch glesbygd genom ett urval av indikatorer. Delstudie 4 syftar till att ge en överblick över tidigare forskning och utveckling på området.

    Några generella slutsatser som kan dras från TÅLA-projektets olika delstudier är att det finns en god medvetenhet hos boende i land- och glesbygd för att det kan ta tid innan hjälp kan fås ifrån de traditionella räddningssystemen (som till exempel polis eller räddningstjänst), ett faktum som också kan bekräftas numerärt. Vissa indikatorer tyder dessutom på att boende på lands- och glesbygden är mer drabbade av olyckor än boende i tätort, vilket ger ett ökat behov av de aktuella resurserna. Detta har lett till att nya typer av lösningar har utvecklats, oftast av de boende, för att bistå vid olyckor, många baserade på självhjälp och frivillighet.

    Tydligt är också att trygghet omfattar mer än bara blåljusverksamheter och stöd från det allmänna. Här inkluderas också behov som el, vatten och möjligheten att handla mat. En stor del av den upplevda tryggheten hos befolkningen kommer från det sociala nätverk som finns i respektive by. Möjligheter till kommunikation är centralt och det är när individen är ensam utan möjlighet till kontakt med omvärlden som den största otryggheten infinner sig.

    Det framkom under projektet flera exempel på samverkan och de som medverkar framhåller vikten av att känna varandra innan insatsen, för att bästa möjliga resultat ska uppnås. Såväl de båda kvalitativa studierna som kunskapsöversikten pekar på att en trolig väg till framgång för en ökad säkerhet och trygghet på landsbygden bygger på att de lokala resurserna och strukturerna nyttjas i samverkan med de traditionella räddningsresurserna. Detta innebär att det bör vara möjligt att stärka dels de boendes möjligheter att hjälpa sig själva och att hjälpa varandra, men också att nyttja organisationer som idag inte tillhör blåljusmyndigheterna för att i samverkan med räddningstjänsten, sjukvården och polisen kunna bistå vid olyckor, akuta sjukdomsförlopp och andra relevanta händelser. Viktigt att beakta i detta sammanhang är då att använda de befintliga strukturer som existerar bland såväl boende som olika organisationer, för att på bästa sätt kunna dra nytta av den lokala kunskap, de resurser och det engagemang som existerar.

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    Tåla : Trygghetsskapande åtgärder för landsbygden
  • 264.
    Andersson, Gustav
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Implementing touch interaction in a casual mobile game2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This thesis is to help developers in the touch design of casual games. The thesis work was made on the development platform Gideros Mobile and much of the thesis theory and methods will be based on that work. The purpose of the report is to show what one should think about when making a casual game in a touch design perspective, like taking into account that most people are used to one type of input design (like swiping or tapping), that you should design the game with the purpose to reach out to as a large audience as possible (taking into account people with disabilities) and some small notes on what should be avoided so not to deter people from wanting to play the game. It is important to note that this thesis is built for the purpose of mobile casual games, others will probably not find this thesis relevant.

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  • 265.
    Andersson, Gustav
    et al.
    Linköping University, Department of Computer and Information Science.
    Eriksson, Gustav
    Linköping University, Department of Computer and Information Science.
    Jungmalm, David
    Linköping University, Department of Computer and Information Science.
    Möller Ehrnlund, Björn
    Linköping University, Department of Computer and Information Science.
    Petersson, Julius
    Linköping University, Department of Computer and Information Science.
    Yngesjö, Tim
    Linköping University, Department of Computer and Information Science.
    Plattform för spelifiering inom programmeringskurser2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport beskriver ett arbete som utförts i kursen TDDD96 - Kandidatprojekt i programvaruutveckling. Projektet gick ut på att utveckla en webbplattform för spelifierad tävlingsprogrammering åt UPP-gruppen på Institutionen för datavetenskap vid Linköpings universitet. Plattformen är tänkt att användas i programmeringskurser. Den innehåller funktioner som låter användare ladda upp spel och agenter via en hemsida där agenterna kan spela spelen mot varandra. Produkten består av en klient i form av en hemsida, och en server. Det finns även ett API för att skapa spel till plattformen. Rapporten beskriver dessa delar både på det tekniska planet samt hur utvecklingsprocesserna gick till. Utöver detta presenteras och diskuteras gruppens erfarenheter från projektet samt hur den slutgiltiga produkten förhåller sig till gruppens och kundens mål. Genom att använda kodgranskning under utvecklingen upplevde gruppen en ökad kvalitet på koden, men också att det stävjade utvecklingen i de fall då granskningen tog lång tid. Den viktigaste erfarenheten gruppen tog med sig från detta projekt är att kommunikationen har mycket stor betydelse för resultaten, och bör därför struktureras upp ordentligt. Genom att arbeta med kundens behov som högsta prioritet, dokumentera all kod väl och konstruera systemet modulärt för att främja vidareutveckling, kan en bra och välgjord produkt skapas som ger värde för kunden.

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    kandidatuppsats
  • 266.
    Andersson, Henrik
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Knowledge management and throughput optimization in large-scale software development2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Large-scale software development companies delivering market-driven products have introduced agile methodologies as the way of working to a big extent. Even though there are many benefits with an agile way of working, problems occur when scaling agile because of the increased complexity. One explicit problem area is to evolve deep product knowledge, which is a domain specific knowledge that cannot be developed anywhere else but at the specific workplace. This research aims to identify impediments for developing domain specific knowledge and provide solutions to overcome these challenges in order to optimize knowledge growth and throughput.

    The result of the research shows that impediments occur in four different categories, based on a framework for knowledge sharing drivers. These are people-related, task-related, structure-related and technology-related. The challenging element with knowledge growth is to integrate the training into the feature development process, without affecting the feature throughput negatively.

    The research also shows that by increasing the knowledge sharing, the competence level of the whole organization can be increased, and thereby be beneficial from many perspectives, such as feature-throughput and code quality.

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  • 267.
    Andersson, Henrik
    et al.
    Linköping University, Department of Computer and Information Science.
    Andersson, Robin
    Linköping University, Department of Computer and Information Science.
    Eriksson, Leif
    Linköping University, Department of Computer and Information Science.
    Hagberg, Alfred
    Linköping University, Department of Computer and Information Science.
    Lundgren, Jonathan
    Linköping University, Department of Computer and Information Science.
    Musse, Mustaf
    Linköping University, Department of Computer and Information Science.
    Nylander, Eric
    Linköping University, Department of Computer and Information Science.
    Maskininlärning för automatisk matchning av produkter2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport behandlar det kandidatarbete som har utförts av sju studenter från civilin-genjörsprogrammen datateknik och mjukvaruteknik på Tekniska högskolan vid Linköpingsuniversitet. Projektets mål var att ta fram ett system som via maskininlärning automatisktskapade matchningar mellan företagets interna basprodukter och produkter från diverse le-verantörer. Beställningen av systemet gjordes av Byggvarulistan i Sverige AB.

    Det utvecklade systemet ska lösa problemet företaget hade med att behöva göra alla match-ningar manuellt. Systemet innehåller en maskininlärningsdel som utför matchningarna ochett administrationsgränssnitt för att korrigera och acceptera dessa matchningar. Utvecklingenav systemet har behövts anpassas till de rådande förutsättningarna med visst brus i kundensdatabas. Graden av nytta som kunden kommer utvinna från systemet beror därför delvispå hur kvaliteten på databasens innehåll kan förbättras för att ge bättre förutsättningar tillmatchningssystemet.

    Rapporten beskriver hur utvecklingen av systemet har skett samt vad det slutgiltiga systemetblev. Detta gjordes utifrån en analys av de använda utvecklingsprocesserna och det slutgil-tiga systemet i ett bredare sammanhang. Det finns även sju individuella bidrag från varderaprojektmedlem där denne utvärderar ett arbetsmetod, algoritm, roll eller liknande relaterattill projektet.

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  • 268.
    Andersson, Ida
    Linköping University, Department of Computer and Information Science.
    Design of Hosted ASP Solution for an Imaging Informatics System2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    PACS (Picture Archiving and Communication System) are IT systems used for distributing, viewing and archiving digital images in radiology. Sectra Imtec AB develops and markets Sectra's PACS systems as large enterprise solutions where the customers pay for hardware, software licenses and support.

    The background to the study was that interesting business opportunities lies in providing Sectra PACS as a hosted ASP (Application Service Provider) solution through the Internet. This solution would make it possible to run PACS clients connected to the same server on many different sites, requiring only an internet connection. It would decrease the need of on-site hardware, software and service. The purpose of the study is to investigate obstacles and opportunities for development, adaptation and integration of a hosted ASP solution for the current Sectra PACS and to develop a prototype based on these investigations.

    The method Case Study Research is used to develop a lo-fi (low fidelity) prototype for hosted ASP solution for Sectra PACS. User analysis is made through PACT (People, Activities, Contexts and Technologies) analysis, the stakeholder model and by visiting a clinic.

    Focus has been on developing a prototype where changes to the current Sectra PACS are kept on a minimum level. This has resulted in that the hosted ASP solution could be implemented without a lot of new development, only small changes in the current Sectra PACS are necessary. The lo-fi prototype provides an overview of the hosted ASP solution and covers different areas; from server configurations to client configuration and legal aspects.

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  • 269.
    Andersson, Jesper
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    A deployment system for pervasive computing2000In: Proceedings. International Conference on  Software Maintenance, 2000., 2000, p. 262-270Conference paper (Other academic)
    Abstract [en]

    Software has for a long time been used for controlling different systems. Today, there is a trend towards integrating more software in consumer electronics, home appliances, cars etc. Suddenly software is moving from traditional environments, such as the desktop computer into new and unknown territory. This will influence many aspects of the software engineering process; above all, several new problems have arisen in the domain of software deployment. How can software be effectively deployed in these environments? Current deployment strategies are not directly applicable. The paper discusses problems with current deployment models and proposes a new, modified model. A deployment model for pervasive computing must support component based development, different delivery models, and installation and activation strategies. Support for dynamic installation and activation (i.e. making modifications without de-activating the software), is especially important. We introduce a prototype implementation, the Java Distributed Run-time Updating Management System (JDRUMS), which we have used as a vehicle for eliciting requirements for our deployment model

  • 270.
    Andersson, Jesper
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Dynamic software architectures2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Software architecture is a software engineering discipline that provides notations and processes for high-level partitioning of systems' responsibilities early in the software design process. This thesis is concerned with a specific subclass of systems, systems with a dynamic software architecture. They have practical applications in various domains such as high-availability systems and ubiquitous computing.

    In a dynamic software architecture, the set of architectural elements and the configuration of these elements may change at run-time. These modifications are motivated by changed system requirements or by changed execution environments. The implications of change events may be the addition of new functionality or re-configuration to meet new Quality of Service requirements.

    This thesis investigates new modeling and implementation techniques for dynamic software architectures. The field of Dynamic Architecture is surveyed and a common ground defined. We introduce new concepts and techniques that simplify understanding, modeling, and implementation of systems with a dynamic architecture, with this common ground as our starting point. In addition, we investigate practical use and reuse of quality implementations, where a dynamic software architecture is a fundamental design principle.

    The main contributions are a taxonomy, a classification, and a set of architectural patterns for dynamic software architecture. The taxonomy and classification support analysis, while the patterns affect design and implementation work directly. The investigation of practical applications of dynamic architectures identifies several issues concerned with use and reuse, and discusses alternatives and solutions where possible.

    The results are based on surveys, case studies, and exploratory development of dynamic software architectures in different application domains using several approaches. The taxonomy, classification and architecture patterns are evaluated through several experimental prototypes, among others, a high-performance scientific computing platform.

    List of papers
    1. A classification of dynamic software architectures
    Open this publication in new window or tab >>A classification of dynamic software architectures
    2005 (English)Report (Other academic)
    Abstract [en]

    A recent trend in computing is towards more autonomous software systems. This is mainly driven by that our daily life more and more depends on computers and software. Areas like ubiquitous computing with small (embedded) systems and their antipodes world-wide distributed systems require different support in terms of flexibility and availability. Systems must be able to adapt to changes in the environment, including self-healing and adaptation. Users can not take on the tedious task of constantly maintaining and updating their software packages to each and every change. This paper discusses one of the foundations for developers of these systems, dynamic architecture. We investigate the existing body of work in the area and identify dimensions and aspects of dynamically changing arcbitectures. Continuing, we use this division creating a dassification of four fundamental dynamic architecture dasses: Dynamic, Adaptive, Constructive, and Reflective. These four are presented as architectural patterns and their possible application areas are discussed.

    Publisher
    p. 51
    Series
    Technical report, ISSN 1650-2647 ; 04122
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12965 (URN)
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2012-11-20
    2. Development and use of dynamic product-line architectures
    Open this publication in new window or tab >>Development and use of dynamic product-line architectures
    2005 (English)In: IEE Proceedings - Software, ISSN 1462-5970, E-ISSN 1463-9831, Vol. 152, no 1, p. 15-28Article in journal (Refereed) Published
    Abstract [en]

    Software product families are used to improve reuse and shorten lead times, with several positive side effects such as improved quality and lowered cost. This paper presents the results of a case study conducted at four Swedish companies that are involved in either the development of or development with a software product family. We identify and discuss several issues such as inter-organizational development of platforms, platforms that employ dynamism, and platforms as a vehicle to achieve certain quality attributes. We analyze issues and demonstrate how these can be deduced to shortcomings in scoping and variability management for non-functional quality attributes and dynamic architectures.

    Keywords
    decision making; object-oriented methods; software architecture; software development management; software libraries; software prototyping; software quality; software reusability; software product families; Swedish companies; inter-organisational development; dynamic reconfiguration; dynamic product-line architectures
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12966 (URN)10.1049/ip-sen:20041007 (DOI)
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2017-12-13
    3. A deployment system for pervasive computing
    Open this publication in new window or tab >>A deployment system for pervasive computing
    2000 (English)In: Proceedings. International Conference on  Software Maintenance, 2000., 2000, p. 262-270Conference paper, Published paper (Other academic)
    Abstract [en]

    Software has for a long time been used for controlling different systems. Today, there is a trend towards integrating more software in consumer electronics, home appliances, cars etc. Suddenly software is moving from traditional environments, such as the desktop computer into new and unknown territory. This will influence many aspects of the software engineering process; above all, several new problems have arisen in the domain of software deployment. How can software be effectively deployed in these environments? Current deployment strategies are not directly applicable. The paper discusses problems with current deployment models and proposes a new, modified model. A deployment model for pervasive computing must support component based development, different delivery models, and installation and activation strategies. Support for dynamic installation and activation (i.e. making modifications without de-activating the software), is especially important. We introduce a prototype implementation, the Java Distributed Run-time Updating Management System (JDRUMS), which we have used as a vehicle for eliciting requirements for our deployment model

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12967 (URN)10.1109/ICSM.2000.883058 (DOI)0-7695-0753-0 (ISBN)
    Conference
    International Conference on Software Maintenance (ICSM' 2000), San José, October
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2012-11-20
    4. Reconfigurable scientific applications on GRID services
    Open this publication in new window or tab >>Reconfigurable scientific applications on GRID services
    2005 (English)In: Advances in Grid Computing: European Grid Conference, Amsterdam, The Netherlands, February 14-16, 2005, Revised Selected Papers / [ed] Peter M. A. Sloot, Alfons G. Hoekstra, Thierry Priol, Alexander Reinefeld, Marian Bubak, Springer Berlin/Heidelberg, 2005, p. 813-822Chapter in book (Other academic)
    Abstract [en]

    This paper proposes a runtime environment for dynamically changing, parallel scientific applications. This kind of applications is motivated by the LOFAR/LOIS project aiming at a multidisciplinary research platform for natural scientists and engineers. The dynamic infrastructure in turn is than mapped to Grid Services environments.

    Place, publisher, year, edition, pages
    Springer Berlin/Heidelberg, 2005
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 ; 3470
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12968 (URN)10.1007/11508380_83 (DOI)978-3-540-26918-2 (ISBN)978-3-540-32036-4 (ISBN)
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2012-12-11
  • 271.
    Andersson, Jesper
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Towards reactive software architectures1999Licentiate thesis, monograph (Other academic)
  • 272.
    Andersson, Jesper
    et al.
    MSI Universitet Växjö, Sweden.
    Ericsson, Morgan
    MSI Universitet Växjö, Sweden.
    Kessler, Christoph
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Löwe, Welf
    MSI Universitet Växjö, Sweden.
    Profile-Guided Composition2008In: 7th Int. Symposium on Software Composition SC 2008,2008, Berlin: Springer , 2008, p. 157-Conference paper (Refereed)
    Abstract [en]

    We present an approach that generates context-aware, optimized libraries of algorithms and data structures. The search space contains all combinations of implementation variants of algorithms and data structures including dynamically switching and converting between them. Based on profiling, the best implementation for a certain context is precomputed at deployment time and selected at runtime. In our experiments, the profile-guided composition outperforms the individual variants in almost all cases.

  • 273.
    Andersson, Johan
    et al.
    Linköping University, Department of Computer and Information Science.
    Andersson, Katrin
    Linköping University, Department of Computer and Information Science.
    Automated Software Testing in an Embedded Real-Time System2007Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    Today, automated software testing has been implemented successfully in many systems, however there does still exist relatively unexplored areas as how automated testing can be implemented in a real-time embedded system. This problem has been the foundation for the work in this master thesis, to investigate the possibility to implement an automated software testing process for the testing of an embedded real-time system at IVU Traffic Technologies AG in Aachen, Germany.

    The system that has been the test object is the on board system i.box.

    This report contains the result of a literature study in order to present the foundation behind the solution to the problem of the thesis. Questions answered in the study are: when to automate, how to automate and which traps should one avoid when implementing an automated software testing process in an embedded system.

    The process of automating the manual process has contained steps as constructing test cases for automated testing, analysing whether an existing tool should be used or a unique test system needs to be developed. The analysis, based on the requirements on the test system, the literature study and an investigation of available test tools, lead to the development of a new test tool. Due to limited devlopement time and characterstics of the i.box, the new tool was built based on post execution evaluation. The tool was therefore divided into two parts, a part that executed the test and a part that evaluated the result. By implementing an automated test tool it has been proved that it is possible to automate the test process at system test level in the i.box.

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  • 274.
    Andersson, Johannes
    et al.
    Linköping University, Department of Computer and Information Science.
    Thyr, Klas
    Linköping University, Department of Computer and Information Science.
    Datorstödd musikproduktion och tyst kunnande: En studie i design för användbarhet2004Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Inom en yrkesgrupp finns det en samlad kunskap och ett yrkeskunnande. En stor del av denna kunskap är outtalad och svårdefinierad. När man överför arbetet till en datormiljö kan det vara av intresse att utforma programvaran på ett sådant sätt att användarna får möjlighet att utnyttja detta kunnande även här.

    Genom att undersöka hur användare arbetar med ett verktyg, som uppenbarligen är designat för att hjälpa användare genom att låta dem utnyttja sin tidigare kunskap inom området, vill vi söka svar på hur detta kan fungera och vilka för- och nackdelar det medför.

    Det verktyg vi använde för vår undersökning var Reason 2.5, ett musikprogram som erbjuder en simulering av en verklig studiomiljö.

    Vi har under testerna sett tydliga tecken på att användarna utnyttjar sitt tysta kunnande i stor utsträckning då de arbetar med gränssnittet. Det stora användandet av metaforer och simuleringar gör att användarna känner igen sig, men det innebär också begränsningar i möjlig arbetsgång. Vi har även sett att man med denna typ av gränssnitt kan erhålla en låg inlärningströskel utan att inskränka på experters möjlighet att arbeta effektivt. Den låga inlärningströskeln är dock beroende av användarens tidigare erfarenhet. Ett simulerat gränssnitt bidrar till konserverandet av den traditionella bild av musikproduktion som är djupt rotad inom yrkesgruppen..

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  • 275.
    Andersson, Jonas
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Using React Native and AWS Lambda for cross-platform development in a startup2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When developing mobile applications, the tradition has been to write code specific (native) for each platform they are running on. Usually it’s about writing two separate applications for the biggest platforms, Android and iOS. There exist alternatives to this approach that uses the same code for different platforms.

    React Native is a relatively new cross-platform development framework that makes it possible to use the same code for application to Android and iOS. It also uses native UI-elements as a possible solution for performance issues that is often associated with cross-plattform development.

    This thesis evaluates React Native and compares it against native Android. The implementation is done by replicating the main functionality from a social media application written as a native Android application. However, the application is not made as an exact replica since that could limit the solutions in React Native. The evaluation is done in a Startup company and therefore focuses on aspects important in a Startup.

    Another issue when developing a mobile application is what type of backend that shall be used. Performance, scalability and complexity are all important aspects when choosing a framework or language as a base for the backend architecture.There do exist theoretical frameworks that could be used when building the backend. However, these frameworks require resources that are often missing in a Startup.

    AWS Lambda is a platform that claims to be a cost-effective way of building a scalable application. In this thesis AWS Lambda is evaluated to see if it can be used to create an automatically scaled backend for this type of social media application.

    The conclusion of the React Native evaluation is that it can be a suitable alternative to native Android development. If the team has previous experience in web development but lack experience in mobile application development it can be a wise choice since it removes the need to learn two frameworks in native Android and native iOS development. React Native is also good to fast create functional prototypes which can be shown to potential investors. The biggest drawback is performance in animations. However, there are often ways to work around that. In our case this drawback did not affect the user experience of the end application.

    The evaluation of AWS Lambda concludes that it is not for every project. In this thesis, the application was a bit too database heavy and therefore the autoscaling ability did not work properly. However, for a service that needs a lot of computing power, AWS Lambda could be a good fit. It could also be a suitable alternative if someone in the team has previous experience in the AWS environment.

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  • 276.
    Andersson, Jonatan
    Linköping University, Department of Computer and Information Science, Human-Centered systems.
    Assessment and Improvement of Initial Learnability in Complex Systems: A Qualitative Study to Promote Intuitive Software Development2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master’s Thesis aimed to assess and propose improvements for initial learnability in Sectra AB’s Picture Archiving Communication System (PACS) by integrating usability engineering and agile software development. Assessing initial learnability and re-designing complex systems is difficult as they have a high skill cap and take longer time to learn in comparison to simpler ones. Further, companies that use agile methodologies often focus on completing small items which might hide the overarching vision of a product that can lead to usability problems. While there are several methods for assessing usability, no research has specifically focused on assessing initial learnability in complex systems. This study however investigates how this may be achieved by combining current methodologies for measuring learnability with usability engineering and agile software development. Initial learnability issues and needs were assessed after evaluating Sectra PACS using 5 participants and analysed using impact mapping as well as conducting a focus group within the organisation that owns the product.

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  • 277.
    Andersson, Jonatan
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Arts and Sciences.
    Design och utkast av ett informationssystem för akutkliniken vid Karolinska Sjukhuset: Design samt utvärdering av prototyp för akutpatienter i väntan på vård2014Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [sv]

    På Karolinska Sjukhusets akutklinik i Solna har man upplevt problem med att personalen får lägga mycket tid på att besvara på patienters frågor som man många gånger tror beror på brist av information. Syftet med studien var att visa på hur ett informationssystem skulle kunna öka den s.k. informationssystems-framgången för Karolinska Sjukhuset med fokus på kopplingen mellan organisationen och patienterna. Detta gjordes genom att skapa två prototyper med hjälp av Adobe Photoshop, Illustrator samt Axure RP som sedan kördes via          en iPhone. Studien ämnade även utvärdera dessa produkter för att hitta eventuella användbarhetsproblem som kan komma att sänka en potentiell användarens nöjdhet. Detta gjorde med hjälp av ett tänka-högt-protokoll som kompletterades av en SUS-enkät.

     

    Studien resulterade i en klargörande analys om vad som var bra- respektive dåligt med de olika prototyperna samt hur de bör tillämpas och vilka resultat det kan få för patienterna, personalen samt Karolinska Sjukhuset som organisation. Det visade sig att en mobilapplikation var något som försöksdeltagarna uppskattade samt tyckte var nödvändigt för att bidra till ett förbättrat informationsflöde på akutkliniken. Vidare bör man dock fortsätta att användbarhetstesta produkten samt experimentera med olika typer med informationspresentation för att optimera gränssnittet samt göra produkten uppdaterad och intressant. 

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    729G40 Kandidatuppsats
  • 278.
    Andersson, Julia
    et al.
    Linköping University, Department of Computer and Information Science.
    Hultqvist, Andreas
    Linköping University, Department of Computer and Information Science.
    Video quality encoding characterization and comparison2019Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Adaptive streaming is a popular technique that allows quality adaption for videos based on the current playback conditions. The purpose of this thesis is to investigate how chunks in video files downloaded from YouTube correlate to each other. We investigate how the chunk size characteristics depend on the category and encoding of the video. The main focus is to analyze the chunk sizes of the video, focusing on distinctness between 360$^\circ$ and 2D videos. This is performed using the YouTube API. The videos are downloaded and analysed using youtube-dl and mkv-info. The results show that chunk sizes for adjacent qualities have higher correlation and that videos having a similarity between scenes have higher correlation. In addition, 360$^\circ$ videos differ primarily from regular 2D videos by the amount of qualities used and a generally higher correlation for all qualities.

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  • 279.
    Andersson, Jörgen
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Bilder av småföretagares ekonomistyrning1995Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Utvecklingen av ekonomisk styrning och även den aktuella debatten inom området är till stora delar koncentrerad till stora företag. Under en seminarieserie om risker i samband med nyföretagande anordnad av Närings- och teknikutvecklingsverket (NUTEK) aktualiserades frågan om ekonomisk styrning i små och nystartade företag.Inför denna studie blev det därför naturligt att ställa sig frågan om hur de teorier och metoder som idag finns till förfogande för ekonomistyrning fungerar i små företag. Syftet med denna studie är att öka insikterna om hur ekonomisk styrning bedrivs i små företag. Detta sker genom att beskriva och analysera den ekonomiska styrningen i ett antal små företag.Undersökningen omfattar intervjuer med nio småföretagsledare. Centrala forskningsfrågor är vilka mål företagsledaren har, vilka ekonomiska verktyg som används, hur beslutsfattande sker samt hur samarbetet med externa aktörer i form av banker, revisorer och konsulter fungerar.Studien visar att långsiktiga mål ofta anges i kvalitativa termer. Mer sällan är de monetära målen konkret formulerade. Företagandet bygger ofta på ett praktiskt kunnande hos företags-ledaren. Affärsidén kan antingen vara explicit formulerad eller mer outtalad. Vidare visas hur komplext beslutsfattande kan vara i den typ av verksamhet som har studerats. I vissa fall kan en sekventiell och rationell beslutsmodell spåras. I andra fall kan irrationella beslutsmodeller beskriva beslutsprocessen. Tydligt är dock att både formella beslutsunderlag och intuition och erfarenhet spelar en viktig roll vid beslutsfattande. Studien visar dessutom att många av de metoder och verktyg som anges inom ekonomistyrningslitteratur också används i de studerade företagen. Vilka verktyg som upplevs som mest betydelsefulla varierar mellan de olika företagsledarna. I studien tolkas användningen av formella ekonomistyrningsmetoder som ett utslag för en avvägning mellan nytta och kostnader i en situation där resurserna är mycket begränsade. Dessutom framkommer att företagsledare har förhållandevis få externa kontakter med vilka affärsverksamheten diskuteras. Av dessa upplevs samarbetet med revisor i många fall som det viktigaste.Slutligen argumenteras för att nya metoder för styrning av verksamheter mot ekonomiska mål behöver utvecklas. Traditionella metoder för ekonomistyrning kan behöva kompletteras med andra metoder där verksamhetens centrala resultatskapande faktorer identifieras och utnyttjas för styrning, vilket kan innebära att icke-monetära mått får en ökad betydelse.

  • 280.
    Andersson, Karl
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Mapping out dependencies in network components in critical infrastructure2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Companies that operate with critical infrastructure face a growing threat from cyber-attacks while at the same time the development in the business is rapidly moving towards a higher level of digitalization. A common type of system in critical infrastructure is supervisory control and data acquisition systems, these systems have properties that can affect their security and will therefore serve as the basis for this thesis work. To stay protected despite systems changes, companies need to make risk assessments in order to analyze how changes will affect the overall system. One thing that is important to focus on is dependencies within the system, this means that not only interaction among computers and networks are concerned but instead a more holistic view of the system need to be considered. This thesis aims to aid the process of a future risk assessment by providing a methodology to be used as a preparatory step before a risk assessment by describing the current situation of the system. This is done by evaluating two system modeling approaches, and also by proposing a number of perspectives that each provides different kind of information about the system’s dependencies. These perspectives are then evaluated by creating system models and dependency graphs, and discussing the outcomes with experts in a utility company to find out their applicability. According to the experts, the proposed perspectives have promising properties that can be useful in future risk assessments as well as in other scenarios. Moreover, the evaluated modeling approaches got positive comments during evaluation and are considered to serve their purpose.

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  • 281.
    Andersson, Karl
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Odlander, Marcus
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Detecting a Distributed Denial-of-Service Attack Using Speed Test Data: A Case Study on an Attack with Nationwide Impact2015Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    This thesis presents a case study that investigates a large Distributed Denial of Service (DDoS) attack and how it affected speed tests observed by the crowd-based speed test application Bredbandskollen.  Furthermore, the thesis also investigates the possibility of using crowd-based speed tests as a method to detect a DDoS attack. This method has very low overhead which makes it an interesting complement to other methods. This thesis also shows that there was a significant deviation in the number of measurements during the DDoS attack considered in the case study compared to the year average. Furthermore, the measurements of the peak day of the attack had a higher average download speed than the year average. Whereas the higher download speed observation at first may appear non-intuitive, we briefly discuss potential explanations and how such positive anomalies could potentially be used to detect attacks. Detecting DDoS attacks early can lead to earlier recognition of network problems which can aid Internet Service Providers (ISPs) in maintaining the availability of their networks.

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  • 282.
    Andersson, Karolina
    et al.
    Linköping University, Department of Management and Economics. Linköping University, Faculty of Arts and Sciences.
    Lindblad, Eva
    Linköping University, The Institute of Technology.
    Mårdsjö Blume, Karin
    Linköping University, The Institute of Technology.
    Nilsson, Ulf
    Linköping University, Department of Computer and Information Science, TCSLAB - Theoretical Computer Science Laboratory. Linköping University, The Institute of Technology.
    Philipsson, Anette
    Linköping University, Faculty of Health Sciences.
    Sundkvist, Maria
    Linköping University, Faculty of Arts and Sciences.
    Livet som doktorand vid Linköpings universitet: Resultat från en enkätundersökning våren 20042005Report (Other academic)
    Abstract [sv]

    I maj 2004 genomfördes en enkätundersökning som riktades till alla doktorander vid Linköpings universitet. De frågeområden som enkäten behandlade inkluderade doktorandens bakgrund och nuvarande status; handledningssituationen samt forsknings- och arbetsmiljö; upplevd särbehandling; forskarutbildningskurser och seminarier; pedagogisk utveckling och undervisning, samt ett antal frågor om hur doktoranden såg på sin forskarutbildning, sin egen insats och på framtiden. Dessutom fanns möjlighet att i fritext ange vad som var positivt respektive negativt med utbildningen, samt att ge förslag på vad som borde förändras och bevaras.

    Enkäten sändes till de cirka 1 360 personer vars e-postadresser var tillgängliga. Närmare 70 %, eller över 900 personer, svarade på enkäten; i ungefär samma omfattning på samtliga fakulteter. Ungefär 5 % uppgav inte någon fakultetstillhörighet. Cirka 45 % av de svarande angav att de var kvinnor, medan 52 % angav att de var män. Det var dock stora variationer i könsfördelningen på fakultetsnivå. Kvinnornas medianålder var något högre än männens, och åldersspridningen var störst på Hälsouniversitetet (HU). Doktoranderna vid Linköpings tekniska högskola (LiTH) var i genomsnitt yngst och en mindre andel av dem, jämfört med övriga, hade hemmavarande barn. Det var en högre andel kvinnor än män som hade hemmavarande barn. Ungefär tre av fyra bodde i Norrköping eller Linköping; en högre andel på LiTH, och en lägre andel på Filosofisk fakultet (Fil fak) och Utbildningsvetenskap (UV).

    Drygt hälften av alla som svarade på frågan hade genomfört hälften eller mindre av sin forskarutbildning. Att vara antagen till licentiatexamen var betydligt vanligare på LiTH (ca 12 %) än på övriga fakulteter. Drygt en fjärdedel av de svarande deltog i någon forskarskola. Det vanligast skälet till att ha gjort ett längre uppehåll var föräldraledighet (8 %) följt av förvärvsarbete (5 %).

    Den vanligaste formen av försörjning var doktorandanställning, men det fanns stora skillnader mellan fakulteterna/motsvarande. HU hade lägst andel. En tredjedel av doktoranderna där hade istället klinisk tjänst. Drygt 80 % av de forskarstuderande vid LiTH hade doktorandanställning. Att enbart ha utbildningsbidrag var sällsynt på samtliga fakulteter, medan kombinationen utbildningsbidrag och assistenttjänst förekom; och då mest frekvent vid HU (drygt 12 %). Den vanligaste uppgivna aktivitetsgraden oavsett fakultet var mellan 90 och 100 % (cirka 25 % av de svarande) medan det på HU fanns en andel – nära 20 % – med mycket låg aktivitetsgrad (0–10 %).

    Doktoranderna var tämligen nöjda med sin utbildning. På en femgradig skala där 5 stod för ”mycket bra” och 1 ”mycket dålig” hamnade medelbetyget på forskarutbildningen på 3,65. Doktoranderna på Filosofisk fakultet och LiTH satte ett något högre betyg, men variationerna mellan fakulteterna var små. Betyget på den egna insatsen sattes av de allra flesta något lägre, medelvärdet var 3,60 på samma skala. De mer detaljerade frågorna om handledning och avhandlingsarbete hade i flera fall högre medelvärde: Handledarens intresse för doktorandens forskning, handledarens läsning av texter, förekomsten av konstruktiv kritik och doktorandens förtroende för handledaren låg nära värdet 4 på den femgradiga skalan. Lägre medelvärden gavs på frågan om handledaren underlättar för doktoranden att få kontakt med andra forskare. Tiden som användes för handledning skiftade en del mellan fakulteterna, men sammanfattningsvis fick cirka 80 % av alla doktorander 1–10 timmar handledning per månad. Filosofisk fakultet och Utbildningsvetenskap hamnade oftare i den nedre delen av intervallet och LiTH samt HU i den högre delen. Uppfattningen att tiden som gavs svarade mot behovet skiftade. Mest nöjda med tidens omfattning var doktoranderna på Utbildningsvetenskap; minst nöjd var man på LiTH.

    På frågorna om forskarutbildningskurser hamnade medelvärdena lägre än på frågorna om handledning. Det var liten skillnad mellan forskarskoledoktorander och övriga på dessa frågor.

    Rent allmänt var alla mycket nöjda med sin forsknings- och arbetsmiljö. Genomgående fick frågorna inom det området högt medelbetyg, med undantag för dem som rörde tillgången till nationella och framför allt internationella forskarnätverk. Den sociala miljön i doktorandgruppen skattades högre än densamma på institutionen i sin helhet.

    Enkäten innehöll även frågor om upplevd positiv och negativ särbehandling. Cirka 50 personer, med få undantag kvinnor, instämde i att de upplevt negativ särbehandling på grund av kön (svarade 4 eller 5 på den femgradiga skalan). Ingen fakultet utmärkte sig i detta avseende.

    Institutioner med en jämn könsfördelning föreföll ha färre fall av upplevd negativ särbehandling. De som upplevt negativ särbehandling på grund av etnisk bakgrund, sexuell läggning eller social bakgrund var färre till antalet. Även positiv särbehandling hade upplevts – antalet svar var av samma storleksordning som för negativ särbehandling. Spridningen över fakulteter och institutioner var även här stor.

    Efter disputationen kunde ungefär 70 % tänka sig en postdoc-period utomlands. Huvudskälet till att inte vilja åka var vanligen hänsyn till familjen, det vill säga situationen för barn och partner. Omkring hälften såg sina möjligheter som goda eller mycket goda att få ett arbete direkt efter examen.

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    Livet som doktorand vid Linköpings universitet : Resultat från en enkätundersökning våren 2004
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  • 283.
    Andersson, Marcus
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Gränssnittsdesign för kundnöjdhet och administration2015Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Kundnöjdhet är en stor inkomstkälla för företag. Det finns många sätt att mäta kundnöjdhet och ett av de nyaste sätten är genom en digital monter placerad i fysisk butik. Denna studie ämnar undersöka hur gränssnitt till en undersökningsapplikation skall utformas för att tilltala en bred målgrupp att lämna omdömen och hur ett användbart gränssnitt till den administrativa sidan för denna applikation kan utformas. Resultaten från utvärderingen av undersökningsgränssnittet visar att det finns designelement som tilltalar vissa användare mer än andra. Detta ger en fingervisning om hur design kan utformas för att vara tilltalande för användarna att lämna omdömen via teknisk plattform. Utvärderingen av administrationsgränssnittet visade att genom att följa teorin kan ett lättanvändbart administrationsgränssnitt skapas.

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  • 284.
    Andersson, Matilda
    Linköping University, Department of Computer and Information Science, Human-Centered systems.
    Användarbehov och kontextuella krav för val av mobil interaktionsteknik: Behovs- och användarundersökning i Scanias verkstäder2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Mobil informationsteknik har på senaste tiden fått mer uppmärksamhet inom industriella applikationer, inte minst inom underhåll och reparation där teknisk dokumentation förekommer i stor utsträckning. Scania har tagit fram ett nytt koncept för interaktion med teknisk dokumentation i verkstaden där en viktig del av konceptet är mobilitet. Scanias förhoppningar är att en ökad möjlighet till mobilitet ska kunna förbättra användarupplevelsen.

    I detta arbete har en observationsstudie genomförts för att identifiera användarnas behov av mobilitet vid reparation och underhållsarbete samt de kontextuella faktorer som påverkar val av mobil interaktionsteknik.

    Fyra olika behov av mobilitet kunde identifieras efter analysen och till dessa kunde olika krav knytas för att skapa ett underlag för bedömning av olika teknikers potential att uppfylla de aktuella behoven.

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    Matilda Andersson - Användarbehov och kontextuella krav för val av mobil interaktionsteknik
  • 285.
    Andersson, Matilda
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Arts and Sciences.
    Vägen mot en guideapplikation: Designförslag till en guide i kulturhistorisk miljö2012Independent thesis Basic level (degree of Bachelor), 12 credits / 18 HE creditsStudent thesis
    Abstract [sv]

    Detta projekt har skapat en design till en applikation, vars mål är att få människor i närnatur och samtidigt möjliggöra för dem att lära sig mer om den kulturhistoria denna natur har att bjuda.I projektet har designen till en guideapplikation för användning i miljö med kulturhistoriska arv undersökts och tagits fram. Projektet är en fallstudie och använder ramverket Minnesmark som en grund för designen.Designen är framtagen genom att använda en målinriktad designmetod och designprocess av Goodwin(2009). Med detta menas att personor och scenarier har varit de främsta verktygen för att generera krav till designen. Krav baseras även på ramverket Minnesmarks möjligheter och begränsningar. Vidare krav kommer även från intervjuer med två olika guider.En första design; en prototyp, utvärderades av åtta personer för att förbättra designen. Utifrån dessa förbättringar togs den slutgiltiga designen fram som består av fem olika delar vilka tillsammans skapar en applikation att använda i miljö med kulturhistoriska arv.

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  • 286.
    Andersson, Mikael
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Utvärdering av ramverket JQuery for mobile2012Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Examensarbetet har utförts på Lawson, som idag gör en satsning mot de mobila användarna. Då det idag finns många olika typer av enheter, webbläsare och operativsystem utvecklas det mobila applikationer till varje plattform vilket medför stora kostnader och längre utvecklingstider. Den här rapporten är skriven i syfte att se över vad det finns för möjligheter att använda ny teknik som HTML5 och CSS3 tillsammans med ramverket jQuery for mobile för att utveckla webbapplikationer.

    För att visa på funktionaliteten och vad man kan göra så har två exempelapplikationer tagits fram och testas på flera olika plattformar/enheter, bland annat en iPad och en Samsung Galaxy Tab 8.9. Koden för dessa applikationer finns som bilaga i rapporten.

    Målet var att se över vad det fanns för stöd för swipes, enhetlig native-design/känsla, kunna använda enhetens kamera och GPS. En hel del, bland annat swipes, GPS och lokal lagring, går att lösa med HTML5 och jQuery for mobile. Men vill man komma åt ännu mer hårdvarunära funktionalitet, så som kamera, så behöver man lägga på ett ramverk, i mitt fall valde jag att utöka arbetet och även se över ramverket Cordova. Det ramverket gjorde att man kunde komma åt kameran i mobilen.

    Slutsatsen av undersökningen är att det går att göra mycket med jQuery for mobile som bygger på webbtekniker som JavaScript, HTML5 och CSS3. Men för att få hårdvarunära funktionalitet behövs det användas en annan typ av ramverk, t.ex. Cordova, som erbjuder ett API mot själva hårdvarufunktionaliteten. För att den funktionaliteten sedan ska fungera måste applikationen kompileras, på samma sätt som en native-applikation. Dock så använder Cordova samma teknik som ramverket jQuery for mobile, så kostnader och utvecklingstid kan hållas nere. Vid små applikationer fungerar det utmärkt att använda denna teknik men vid större kan man behöva göra lite fler prestandatester innan man säkert kan avgöra om tekniken är lämplig.

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  • 287.
    Andersson Naesseth, Christian
    et al.
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Science & Engineering.
    Lindsten, Fredrik
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Science & Engineering.
    Schon, Thomas B.
    Uppsala Univ, Sweden.
    High-Dimensional Filtering Using Nested Sequential Monte Carlo2019In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 67, no 16, p. 4177-4188Article in journal (Refereed)
    Abstract [en]

    Sequential Monte Carlo (SMC) methods comprise one of the most successful approaches to approximate Bayesian filtering. However, SMC without a good proposal distribution can perform poorly, in particular in high dimensions. We propose nested sequential Monte Carlo, a methodology that generalizes the SMC framework by requiring only approximate, properly weighted, samples from the SMC proposal distribution, while still resulting in a correctSMCalgorithm. This way, we can compute an "exact approximation" of, e. g., the locally optimal proposal, and extend the class of models forwhichwe can perform efficient inference using SMC. We showimproved accuracy over other state-of-the-art methods on several spatio-temporal state-space models.

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  • 288.
    Andersson, Niclas
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Compilation of mathematical models to parallel code1996Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Generating parallel code from high-level mathematical models is in its general form an intractable problem. Rather than trying to solve this problem, a more realistic approach is to solve specific problem instances for limited domains.In this thesis, we focus our efforts on problems where the main computation is to solve ordinary differential equation systems. When solving such a system of equations, the major part of the computing time is spent in application specific code, rather than in the serial solver kernel. By applying domain specific knowledge, we can generate efficient parallel code for numerical solution.We investigate automatic parallelisation of the computation of ordinary differential equation systems at three different levels of granularity: equation system level, equation level, and clustered task level. At the clustered task level we employ existing scheduling and clustering algorithms to partition and distribute the computation.Moreover, an interface is provided to express explicit parallelism through annotations in the the mathematical model.This work is performed in the context of ObjectMath, a programming environment and modelling language that supports classes of equation objects, inheritance of equations, and solving systems of equations. The environment is designed to handle realistic problems.

  • 289.
    Andersson, Niclas
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Comparative Evaluation and Industrial Application of Code Generator Generators1992Conference paper (Other academic)
    Abstract [en]

    The past ten to fifteen years has seen active research in the area of automatically generating the code generator part of compilers from formal specifications. However, less work has been done on evaluating and applying these systems in an industrial setting. This paper attempts to fill this gap.Three systems for automatic generation of code generators are evaluated in this paper: CGSS, BEG and TWIG. CGSS is an older Graham-Glanville style system based on pattern matching through parsing, whereas BEG and TWIG are more recent systems based on tree pattern matching combined with dynamic programming. An industrial-strength code generator previously implemented for a special-purpose language using the CGSS system is described and compared in some detail to our new implementation based on the BEG system. Several problems of integrating local and global register allocation within automatically generated code generators are described, and some solutions proposed. We finally conclude that current technology of automatically generating code generators is viable in an industrial setting. However, further research needs to be done on the problem of properly integrating register allocation with instruction selection, when both are generated from declarative specifications.

  • 290.
    Andersson, Niclas
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Generating Parallel Code from Object Oriented Mathematical Models1995In: PPOPP 1995, 1995, p. 48-57Conference paper (Refereed)
    Abstract [en]

    For a long time efficient use of parallel computers has been hindered by dependencies introduced in software through low-level implementation practice. In this paper we present a programming environment and language called Object-Math (Object oriented Mathematical language for scientific computing), which aims at eliminating this problem by allowing the user to represent mathematical equation-based models directly in the system. The system performs analysis of mathematical models to extract parallelism and automatically generates parallel code for numerical solution.In the context of industrial applications in mechanical analysis, we have so far primarily explored generation of parallel code for solving systems of ordinary differential equations (ODEs), in addition to preliminary work on generating code for solving partial differential equations. Two approaches to extracting parallelism have been implemented and evaluated: extracting parallelism at the equation system level and at the single equation level, respectively. We found that for several applications the corresponding systems of equations do not partition well into subsystems. This means that the equation system level approach is of restricted general applicability. Thus, we focused on the equation-level approach which yielded significant parallelism for ODE systems solution. For the bearing simulation applications we present here, the achieved speedup is however critically dependent on low communication latency of the parallel computer.

  • 291.
    Andersson, Niclas
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Object Oriented Mathematical Modelling and Compilation to Parallel Code1997In: Parallel Computing in Optimization / [ed] Athanasios Migdalas, Panos M. Pardalos and Sverre Storøy, Kluwer Academic Publishers, 1997Chapter in book (Other academic)
    Abstract [en]

    The current state of the art in programming for scientific computing is still rather low-level. The mathematical model behind a computing application usually is written using pen and paper, whereas the corresponding numerical software often is developed manually in Fortran or C. This is especially true in application areas such as mechanical analysis, where complex non-linear problems are the norm, and high performance is required. Ideally, a high-level programming environment would provide computer support for these development steps. This motivated the development of the ObjectMath system. Using ObjectMath, complex mathematical models may be structured in an object oriented way, symbolically simplified, and transformed to efficient numerical code in C++ or Fortran.

    However, many scientific computing problems are quite computationally demanding, which makes it desirable to use parallel computers. Unfortunately, generating parallel code from arbitrary mathematical models is an intractable problem. Therefore, we have focused most of our efforts on a specific problem domain where the main computation is to solve ordinary differential equation systems where most of the computing time is spent in application specific code, rather than in the serial solver kernel. We have investigated automatic parallelisation of the computation of ordinary differential equation systems at three different levels of granularity: the equation system level, the equation level, and the clustered task level. At the clustered task level we employ domain specific knowledge and existing scheduling and clustering algorithms to partition and distribute the computation.

  • 292.
    Andersson, Niclas
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Overview and industrial application of code generator generators1996In: Journal of Systems and Software, ISSN 0164-1212, E-ISSN 1873-1228, Vol. 32, no 3, p. 185-214Article in journal (Refereed)
    Abstract [en]

    During the past 10 to 15 years, there has been active research in the area of automatically generating the code generator part of compilers from formal specifications. However, little has been reported on the application of these systems in an industrial setting. This paper attempts to fill this gap, in addition to providing a tutorial overview of the most well-known methods. Four systems for automatic generation of code generators are described in this paper. CGSS, BEG, TWIG and BURG. CGSS is an older Graham-Glanville style system based on pattern matching through parsing, whereas BEG, TWIG, and BURG are more recent systems based on tree pattern matching combined with dynamic programming. An industrial-strength code generator previously implemented for a special-purpose language using the CGSS system is described and compared in some detail to our new implementation based on the BEG system. Several problems of integrating local and global register allocations within automatically generated code generators are described, and some solutions are proposed. In addition, the specification of a full code generator for SUN SPARC with register windows using the BEG system is described. We finally conclude that current technology of automatically generating code generators is viable in an industrial setting. However, further research needs to be done on the problem of properly integrating register allocation and instruction scheduling with instruction selection, when both are generated from declarative specifications.

  • 293.
    Andersson, Niklas
    et al.
    Linköping University, Department of Computer and Information Science, Statistics.
    Hansson, Josef
    Linköping University, Department of Computer and Information Science, Statistics.
    Metodik för detektering av vägåtgärder via tillståndsdata2010Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Swedish Transport Administration has, and manages, a database containing information of the status of road condition on all paved and governmental operated Swedish roads. The purpose of the database is to support the Pavement Management System (PMS). The PMS is used to identify sections of roads where there is a need for treatment, how to allocate resources and to get a general picture of the state of the road network condition. All major treatments should be reported which has not always been done.

    The road condition is measured using a number of indicators on e.g. the roads unevenness. Rut depth is an indicator of the roads transverse unevenness. When a treatment has been done the condition drastically changes, which is also reflected by these indicators.

    The purpose of this master thesis is to; by using existing indicators make predictions to find points in time when a road has been treated.

    We have created a SAS-program based on simple linear regression to analyze rut depth changes over time. The function of the program is to find levels changes in the rut depth trend. A drastic negative change means that a treatment has been made.

    The proportion of roads with an alleged date for the latest treatment earlier than the programs latest detected date was 37 percent. It turned out that there are differences in the proportions of possible treatments found by the software and actually reported roads between different regions. The regions North and Central have the highest proportion of differences. There are also differences between the road groups with various amount of traffic. The differences between the regions do not depend entirely on the fact that the proportion of heavily trafficked roads is greater for some regions.

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  • 294.
    Andersson, Nisa
    et al.
    Linköping University, Department of Computer and Information Science.
    Broman, Nils
    Björn, Martin
    Linköping University, Department of Computer and Information Science.
    Byström, Adrian
    Linköping University, Department of Computer and Information Science.
    Markfjärd, Gabriel
    Linköping University, Department of Computer and Information Science.
    Rasmussen, Christian
    Linköping University, Department of Computer and Information Science.
    Sundberg, Simon
    Linköping University, Department of Computer and Information Science.
    Prediktion av priset på höstvete2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I denna rapport finnes resultatet av kandidatprojektet i kursen TDDD96 som ges av Linköpings universitet. Projektet har utförts av sju studenter på Civilingenjörsprogrammet inom Datateknik och Civilingenjörsprogrammet inom Mjukvaruteknik. Projektet som utförts var ett mjuvaruutvecklingsprojekt, där studenterna utvecklade en webb-applikation för visningen av historisk data från källor relaterade till lantbruk, med fokus på grödan höstvete. Projektet har dessutom innefattat en studie som, med hjälp av enkla maskininlärningstekniker, undersökt om datan är tillräcklig för att ge en prediktion på vad priset kan tänkas vara i framtiden. Rapporten behandlar de tekniska, gruppadministrativa, och informationsinsamlande val som gjorts, samt hur arbetet med utvecklingen har genomförts och vad resultatet av projektet blev. Rapporten innehåller även sju individuella delar, tillhörande var och en av de sju studenterna, där de genomfört en studie på en egen frågeställning. Dessa finnes i slutet av dokumentet.

    Download full text (pdf)
    rapport
  • 295. Order onlineBuy this publication >>
    Andersson, Olov
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Learning to Make Safe Real-Time Decisions Under Uncertainty for Autonomous Robots2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Robots are increasingly expected to go beyond controlled environments in laboratories and factories, to act autonomously in real-world workplaces and public spaces. Autonomous robots navigating the real world have to contend with a great deal of uncertainty, which poses additional challenges. Uncertainty in the real world accrues from several sources. Some of it may originate from imperfect internal models of reality. Other uncertainty is inherent, a direct side effect of partial observability induced by sensor limitations and occlusions. Regardless of the source, the resulting decision problem is unfortunately computationally intractable under uncertainty. This poses a great challenge as the real world is also dynamic. It  will not pause while the robot computes a solution. Autonomous robots navigating among people, for example in traffic, need to be able to make split-second decisions. Uncertainty is therefore often neglected in practice, with potentially catastrophic consequences when something unexpected happens. The aim of this thesis is to leverage recent advances in machine learning to compute safe real-time approximations to decision-making under uncertainty for real-world robots. We explore a range of methods, from probabilistic to deep learning, as well as different combinations with optimization-based methods from robotics, planning and control. Driven by applications in robot navigation, and grounded in experiments with real autonomous quadcopters, we address several parts of this problem. From reducing uncertainty by learning better models, to directly approximating the decision problem itself, all the while attempting to satisfy both the safety and real-time requirements of real-world autonomy.

    List of papers
    1. Model-Predictive Control with Stochastic Collision Avoidance using Bayesian Policy Optimization
    Open this publication in new window or tab >>Model-Predictive Control with Stochastic Collision Avoidance using Bayesian Policy Optimization
    2016 (English)In: IEEE International Conference on Robotics and Automation (ICRA), 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 4597-4604Conference paper, Published paper (Refereed)
    Abstract [en]

    Robots are increasingly expected to move out of the controlled environment of research labs and into populated streets and workplaces. Collision avoidance in such cluttered and dynamic environments is of increasing importance as robots gain more autonomy. However, efficient avoidance is fundamentally difficult since computing safe trajectories may require considering both dynamics and uncertainty. While heuristics are often used in practice, we take a holistic stochastic trajectory optimization perspective that merges both collision avoidance and control. We examine dynamic obstacles moving without prior coordination, like pedestrians or vehicles. We find that common stochastic simplifications lead to poor approximations when obstacle behavior is difficult to predict. We instead compute efficient approximations by drawing upon techniques from machine learning. We propose to combine policy search with model-predictive control. This allows us to use recent fast constrained model-predictive control solvers, while gaining the stochastic properties of policy-based methods. We exploit recent advances in Bayesian optimization to efficiently solve the resulting probabilistically-constrained policy optimization problems. Finally, we present a real-time implementation of an obstacle avoiding controller for a quadcopter. We demonstrate the results in simulation as well as with real flight experiments.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    Series
    Proceedings of IEEE International Conference on Robotics and Automation, ISSN 1050-4729
    Keywords
    Robot Learning, Collision Avoidance, Robotics, Bayesian Optimization, Model Predictive Control
    National Category
    Robotics Computer Sciences
    Identifiers
    urn:nbn:se:liu:diva-126769 (URN)10.1109/ICRA.2016.7487661 (DOI)000389516203138 ()
    Conference
    IEEE International Conference on Robotics and Automation (ICRA), 2016, Stockholm, May 16-21
    Projects
    CADICSELLIITNFFP6CUASSHERPA
    Funder
    Linnaeus research environment CADICSELLIIT - The Linköping‐Lund Initiative on IT and Mobile CommunicationsEU, FP7, Seventh Framework ProgrammeSwedish Foundation for Strategic Research
    Available from: 2016-04-04 Created: 2016-04-04 Last updated: 2020-03-26Bibliographically approved
    2. Receding-Horizon Lattice-based Motion Planning with Dynamic Obstacle Avoidance
    Open this publication in new window or tab >>Receding-Horizon Lattice-based Motion Planning with Dynamic Obstacle Avoidance
    Show others...
    2018 (English)In: 2018 IEEE Conference on Decision and Control (CDC), Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 4467-4474Conference paper, Published paper (Refereed)
    Abstract [en]

    A key requirement of autonomous vehicles is the capability to safely navigate in their environment. However, outside of controlled environments, safe navigation is a very difficult problem. In particular, the real-world often contains both complex 3D structure, and dynamic obstacles such as people or other vehicles. Dynamic obstacles are particularly challenging, as a principled solution requires planning trajectories with regard to both vehicle dynamics, and the motion of the obstacles. Additionally, the real-time requirements imposed by obstacle motion, coupled with real-world computational limitations, make classical optimality and completeness guarantees difficult to satisfy. We present a unified optimization-based motion planning and control solution, that can navigate in the presence of both static and dynamic obstacles. By combining optimal and receding-horizon control, with temporal multi-resolution lattices, we can precompute optimal motion primitives, and allow real-time planning of physically-feasible trajectories in complex environments with dynamic obstacles. We demonstrate the framework by solving difficult indoor 3D quadcopter navigation scenarios, where it is necessary to plan in time. Including waiting on, and taking detours around, the motions of other people and quadcopters.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2018
    Series
    Conference on Decision and Control (CDC), ISSN 2576-2370 ; 2018
    Keywords
    Motion Planning, Optimal Control, Autonomous System, UAV, Dynamic Obstacle Avoidance, Robotics
    National Category
    Control Engineering
    Identifiers
    urn:nbn:se:liu:diva-152131 (URN)10.1109/CDC.2018.8618964 (DOI)9781538613955 (ISBN)9781538613948 (ISBN)9781538613962 (ISBN)
    Conference
    2018 IEEE 57th Annual Conference on Decision and Control (CDC),17-19 December, Miami, Florida, USA
    Funder
    VINNOVAKnut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research ELLIIT - The Linköping‐Lund Initiative on IT and Mobile CommunicationsSwedish Research CouncilLinnaeus research environment CADICSCUGS (National Graduate School in Computer Science)
    Note

    This work was partially supported by FFI/VINNOVA, the Wallenberg Artificial Intelligence, Autonomous Systems and Software Program (WASP) funded by Knut and Alice Wallenberg Foundation, the Swedish Foundation for Strategic Research (SSF) project Symbicloud, the ELLIIT Excellence Center at Linköping-Lund for Information Technology, Swedish Research Council (VR) Linnaeus Center CADICS, and the National Graduate School in Computer Science, Sweden (CUGS).

    Available from: 2018-10-18 Created: 2018-10-18 Last updated: 2020-03-26Bibliographically approved
    3. Deep Learning Quadcopter Control via Risk-Aware Active Learning
    Open this publication in new window or tab >>Deep Learning Quadcopter Control via Risk-Aware Active Learning
    2017 (English)In: Proceedings of The Thirty-first AAAI Conference on Artificial Intelligence (AAAI) / [ed] Satinder Singh and Shaul Markovitch, AAAI Press, 2017, Vol. 5, p. 3812-3818Conference paper, Published paper (Refereed)
    Abstract [en]

    Modern optimization-based approaches to control increasingly allow automatic generation of complex behavior from only a model and an objective. Recent years has seen growing interest in fast solvers to also allow real-time operation on robots, but the computational cost of such trajectory optimization remains prohibitive for many applications. In this paper we examine a novel deep neural network approximation and validate it on a safe navigation problem with a real nano-quadcopter. As the risk of costly failures is a major concern with real robots, we propose a risk-aware resampling technique. Contrary to prior work this active learning approach is easy to use with existing solvers for trajectory optimization, as well as deep learning. We demonstrate the efficacy of the approach on a difficult collision avoidance problem with non-cooperative moving obstacles. Our findings indicate that the resulting neural network approximations are least 50 times faster than the trajectory optimizer while still satisfying the safety requirements. We demonstrate the potential of the approach by implementing a synthesized deep neural network policy on the nano-quadcopter microcontroller.

    Place, publisher, year, edition, pages
    AAAI Press, 2017
    Series
    Proceedings of the AAAI Conference on Artificial Intelligence, ISSN 2159-5399, E-ISSN 2374-3468 ; 5
    National Category
    Computer Vision and Robotics (Autonomous Systems) Computer Sciences
    Identifiers
    urn:nbn:se:liu:diva-132800 (URN)978-1-57735-784-1 (ISBN)
    Conference
    Thirty-First AAAI Conference on Artificial Intelligence (AAAI), 2017, San Francisco, February 4–9.
    Projects
    ELLIITCADICSNFFP6SYMBICLOUDCUGS
    Funder
    Linnaeus research environment CADICSELLIIT - The Linköping‐Lund Initiative on IT and Mobile CommunicationsEU, FP7, Seventh Framework ProgrammeCUGS (National Graduate School in Computer Science)Swedish Foundation for Strategic Research
    Available from: 2016-11-25 Created: 2016-11-25 Last updated: 2020-03-26Bibliographically approved
    4. Deep RL for Autonomous Robots: Limitations and Safety Challenges
    Open this publication in new window or tab >>Deep RL for Autonomous Robots: Limitations and Safety Challenges
    2019 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    With the rise of deep reinforcement learning, there has also been a string of successes on continuous control problems using physics simulators. This has lead to some optimism regarding use in autonomous robots and vehicles. However, to successful apply such techniques to the real world requires a firm grasp of their limitations. As recent work has raised questions of how diverse these simulation benchmarks really are, we here instead analyze a popular deep RL approach on toy examples from robot obstacle avoidance. We find that these converge very slowly, if at all, to safe policies. We identify convergence issues on stochastic environments and local minima as problems that warrant more attention for safety-critical control applications.

    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:liu:diva-164581 (URN)
    Conference
    European Symposium on Artificial Neural Networks, Computational Intelligence and Machine Learning
    Funder
    Wallenberg AI, Autonomous Systems and Software Program (WASP)Swedish Foundation for Strategic Research ELLIIT - The Linköping‐Lund Initiative on IT and Mobile Communications
    Available from: 2020-03-26 Created: 2020-03-26 Last updated: 2020-04-06
    5. Model-Based Reinforcement Learning in Continuous Environments Using Real-Time Constrained Optimization
    Open this publication in new window or tab >>Model-Based Reinforcement Learning in Continuous Environments Using Real-Time Constrained Optimization
    2015 (English)In: Proceedings of the Twenty-Ninth AAAI Conference on Artificial Intelligence (AAAI) / [ed] Blai Bonet and Sven Koenig, AAAI Press, 2015, p. 2497-2503Conference paper, Published paper (Refereed)
    Abstract [en]

    Reinforcement learning for robot control tasks in continuous environments is a challenging problem due to the dimensionality of the state and action spaces, time and resource costs for learning with a real robot as well as constraints imposed for its safe operation. In this paper we propose a model-based reinforcement learning approach for continuous environments with constraints. The approach combines model-based reinforcement learning with recent advances in approximate optimal control. This results in a bounded-rationality agent that makes decisions in real-time by efficiently solving a sequence of constrained optimization problems on learned sparse Gaussian process models. Such a combination has several advantages. No high-dimensional policy needs to be computed or stored while the learning problem often reduces to a set of lower-dimensional models of the dynamics. In addition, hard constraints can easily be included and objectives can also be changed in real-time to allow for multiple or dynamic tasks. The efficacy of the approach is demonstrated on both an extended cart pole domain and a challenging quadcopter navigation task using real data.

    Place, publisher, year, edition, pages
    AAAI Press, 2015
    Keywords
    Reinforcement Learning, Gaussian Processes, Optimization, Robotics
    National Category
    Computer Sciences Computer Vision and Robotics (Autonomous Systems)
    Identifiers
    urn:nbn:se:liu:diva-113385 (URN)978-1-57735-698-1 (ISBN)
    Conference
    Twenty-Ninth AAAI Conference on Artificial Intelligence (AAAI), January 25-30, 2015, Austin, Texas, USA.
    Funder
    Linnaeus research environment CADICSeLLIIT - The Linköping‐Lund Initiative on IT and Mobile CommunicationsSwedish Foundation for Strategic Research VINNOVAEU, FP7, Seventh Framework Programme
    Available from: 2015-01-16 Created: 2015-01-16 Last updated: 2020-03-26Bibliographically approved
    6. Real-Time Robotic Search using Structural Spatial Point Processes
    Open this publication in new window or tab >>Real-Time Robotic Search using Structural Spatial Point Processes
    Show others...
    2019 (English)Conference paper, Published paper (Refereed)
    National Category
    Computer and Information Sciences
    Identifiers
    urn:nbn:se:liu:diva-159698 (URN)
    Conference
    Proceedings of the 35th Conference on Uncertainty in Artificial Intelligence (UAI 2019), Tel Aviv, Israel, July 22-25, 2019
    Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2020-03-26Bibliographically approved
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    presentationsbild
  • 296. Order onlineBuy this publication >>
    Andersson, Olov
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Methods for Scalable and Safe Robot Learning2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Robots are increasingly expected to go beyond controlled environments in laboratories and factories, to enter real-world public spaces and homes. However, robot behavior is still usually engineered for narrowly defined scenarios. To manually encode robot behavior that works within complex real world environments, such as busy work places or cluttered homes, can be a daunting task. In addition, such robots may require a high degree of autonomy to be practical, which imposes stringent requirements on safety and robustness. \setlength{\parindent}{2em}\setlength{\parskip}{0em}The aim of this thesis is to examine methods for automatically learning safe robot behavior, lowering the costs of synthesizing behavior for complex real-world situations. To avoid task-specific assumptions, we approach this from a data-driven machine learning perspective. The strength of machine learning is its generality, given sufficient data it can learn to approximate any task. However, being embodied agents in the real-world, robots pose a number of difficulties for machine learning. These include real-time requirements with limited computational resources, the cost and effort of operating and collecting data with real robots, as well as safety issues for both the robot and human bystanders.While machine learning is general by nature, overcoming the difficulties with real-world robots outlined above remains a challenge. In this thesis we look for a middle ground on robot learning, leveraging the strengths of both data-driven machine learning, as well as engineering techniques from robotics and control. This includes combing data-driven world models with fast techniques for planning motions under safety constraints, using machine learning to generalize such techniques to problems with high uncertainty, as well as using machine learning to find computationally efficient approximations for use on small embedded systems.We demonstrate such behavior synthesis techniques with real robots, solving a class of difficult dynamic collision avoidance problems under uncertainty, such as induced by the presence of humans without prior coordination. Initially using online planning offloaded to a desktop CPU, and ultimately as a deep neural network policy embedded on board a 7 quadcopter.

    List of papers
    1. Model-Based Reinforcement Learning in Continuous Environments Using Real-Time Constrained Optimization
    Open this publication in new window or tab >>Model-Based Reinforcement Learning in Continuous Environments Using Real-Time Constrained Optimization
    2015 (English)In: Proceedings of the Twenty-Ninth AAAI Conference on Artificial Intelligence (AAAI) / [ed] Blai Bonet and Sven Koenig, AAAI Press, 2015, p. 2497-2503Conference paper, Published paper (Refereed)
    Abstract [en]

    Reinforcement learning for robot control tasks in continuous environments is a challenging problem due to the dimensionality of the state and action spaces, time and resource costs for learning with a real robot as well as constraints imposed for its safe operation. In this paper we propose a model-based reinforcement learning approach for continuous environments with constraints. The approach combines model-based reinforcement learning with recent advances in approximate optimal control. This results in a bounded-rationality agent that makes decisions in real-time by efficiently solving a sequence of constrained optimization problems on learned sparse Gaussian process models. Such a combination has several advantages. No high-dimensional policy needs to be computed or stored while the learning problem often reduces to a set of lower-dimensional models of the dynamics. In addition, hard constraints can easily be included and objectives can also be changed in real-time to allow for multiple or dynamic tasks. The efficacy of the approach is demonstrated on both an extended cart pole domain and a challenging quadcopter navigation task using real data.

    Place, publisher, year, edition, pages
    AAAI Press, 2015
    Keywords
    Reinforcement Learning, Gaussian Processes, Optimization, Robotics
    National Category
    Computer Sciences Computer Vision and Robotics (Autonomous Systems)
    Identifiers
    urn:nbn:se:liu:diva-113385 (URN)978-1-57735-698-1 (ISBN)
    Conference
    Twenty-Ninth AAAI Conference on Artificial Intelligence (AAAI), January 25-30, 2015, Austin, Texas, USA.
    Funder
    Linnaeus research environment CADICSeLLIIT - The Linköping‐Lund Initiative on IT and Mobile CommunicationsSwedish Foundation for Strategic Research VINNOVAEU, FP7, Seventh Framework Programme
    Available from: 2015-01-16 Created: 2015-01-16 Last updated: 2020-03-26Bibliographically approved
    2. Model-Predictive Control with Stochastic Collision Avoidance using Bayesian Policy Optimization
    Open this publication in new window or tab >>Model-Predictive Control with Stochastic Collision Avoidance using Bayesian Policy Optimization
    2016 (English)In: IEEE International Conference on Robotics and Automation (ICRA), 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 4597-4604Conference paper, Published paper (Refereed)
    Abstract [en]

    Robots are increasingly expected to move out of the controlled environment of research labs and into populated streets and workplaces. Collision avoidance in such cluttered and dynamic environments is of increasing importance as robots gain more autonomy. However, efficient avoidance is fundamentally difficult since computing safe trajectories may require considering both dynamics and uncertainty. While heuristics are often used in practice, we take a holistic stochastic trajectory optimization perspective that merges both collision avoidance and control. We examine dynamic obstacles moving without prior coordination, like pedestrians or vehicles. We find that common stochastic simplifications lead to poor approximations when obstacle behavior is difficult to predict. We instead compute efficient approximations by drawing upon techniques from machine learning. We propose to combine policy search with model-predictive control. This allows us to use recent fast constrained model-predictive control solvers, while gaining the stochastic properties of policy-based methods. We exploit recent advances in Bayesian optimization to efficiently solve the resulting probabilistically-constrained policy optimization problems. Finally, we present a real-time implementation of an obstacle avoiding controller for a quadcopter. We demonstrate the results in simulation as well as with real flight experiments.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    Series
    Proceedings of IEEE International Conference on Robotics and Automation, ISSN 1050-4729
    Keywords
    Robot Learning, Collision Avoidance, Robotics, Bayesian Optimization, Model Predictive Control
    National Category
    Robotics Computer Sciences
    Identifiers
    urn:nbn:se:liu:diva-126769 (URN)10.1109/ICRA.2016.7487661 (DOI)000389516203138 ()
    Conference
    IEEE International Conference on Robotics and Automation (ICRA), 2016, Stockholm, May 16-21
    Projects
    CADICSELLIITNFFP6CUASSHERPA
    Funder
    Linnaeus research environment CADICSELLIIT - The Linköping‐Lund Initiative on IT and Mobile CommunicationsEU, FP7, Seventh Framework ProgrammeSwedish Foundation for Strategic Research
    Available from: 2016-04-04 Created: 2016-04-04 Last updated: 2020-03-26Bibliographically approved
    3. Deep Learning Quadcopter Control via Risk-Aware Active Learning
    Open this publication in new window or tab >>Deep Learning Quadcopter Control via Risk-Aware Active Learning
    2017 (English)In: Proceedings of The Thirty-first AAAI Conference on Artificial Intelligence (AAAI) / [ed] Satinder Singh and Shaul Markovitch, AAAI Press, 2017, Vol. 5, p. 3812-3818Conference paper, Published paper (Refereed)
    Abstract [en]

    Modern optimization-based approaches to control increasingly allow automatic generation of complex behavior from only a model and an objective. Recent years has seen growing interest in fast solvers to also allow real-time operation on robots, but the computational cost of such trajectory optimization remains prohibitive for many applications. In this paper we examine a novel deep neural network approximation and validate it on a safe navigation problem with a real nano-quadcopter. As the risk of costly failures is a major concern with real robots, we propose a risk-aware resampling technique. Contrary to prior work this active learning approach is easy to use with existing solvers for trajectory optimization, as well as deep learning. We demonstrate the efficacy of the approach on a difficult collision avoidance problem with non-cooperative moving obstacles. Our findings indicate that the resulting neural network approximations are least 50 times faster than the trajectory optimizer while still satisfying the safety requirements. We demonstrate the potential of the approach by implementing a synthesized deep neural network policy on the nano-quadcopter microcontroller.

    Place, publisher, year, edition, pages
    AAAI Press, 2017
    Series
    Proceedings of the AAAI Conference on Artificial Intelligence, ISSN 2159-5399, E-ISSN 2374-3468 ; 5
    National Category
    Computer Vision and Robotics (Autonomous Systems) Computer Sciences
    Identifiers
    urn:nbn:se:liu:diva-132800 (URN)978-1-57735-784-1 (ISBN)
    Conference
    Thirty-First AAAI Conference on Artificial Intelligence (AAAI), 2017, San Francisco, February 4–9.
    Projects
    ELLIITCADICSNFFP6SYMBICLOUDCUGS
    Funder
    Linnaeus research environment CADICSELLIIT - The Linköping‐Lund Initiative on IT and Mobile CommunicationsEU, FP7, Seventh Framework ProgrammeCUGS (National Graduate School in Computer Science)Swedish Foundation for Strategic Research
    Available from: 2016-11-25 Created: 2016-11-25 Last updated: 2020-03-26Bibliographically approved
    Download full text (pdf)
    fulltext
    Download (pdf)
    omslag
    Download (jpg)
    presentationsbild
  • 297.
    Andersson, Olov
    et al.
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems.
    Doherty, Patrick
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Deep RL for Autonomous Robots: Limitations and Safety Challenges2019Conference paper (Refereed)
    Abstract [en]

    With the rise of deep reinforcement learning, there has also been a string of successes on continuous control problems using physics simulators. This has lead to some optimism regarding use in autonomous robots and vehicles. However, to successful apply such techniques to the real world requires a firm grasp of their limitations. As recent work has raised questions of how diverse these simulation benchmarks really are, we here instead analyze a popular deep RL approach on toy examples from robot obstacle avoidance. We find that these converge very slowly, if at all, to safe policies. We identify convergence issues on stochastic environments and local minima as problems that warrant more attention for safety-critical control applications.

  • 298.
    Andersson, Olov
    et al.
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Intergrated Computer systems. Linköping University, The Institute of Technology.
    Heintz, Fredrik
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Intergrated Computer systems. Linköping University, The Institute of Technology.
    Doherty, Patrick
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Intergrated Computer systems. Linköping University, The Institute of Technology.
    Model-Based Reinforcement Learning in Continuous Environments Using Real-Time Constrained Optimization2015In: Proceedings of the Twenty-Ninth AAAI Conference on Artificial Intelligence (AAAI) / [ed] Blai Bonet and Sven Koenig, AAAI Press, 2015, p. 2497-2503Conference paper (Refereed)
    Abstract [en]

    Reinforcement learning for robot control tasks in continuous environments is a challenging problem due to the dimensionality of the state and action spaces, time and resource costs for learning with a real robot as well as constraints imposed for its safe operation. In this paper we propose a model-based reinforcement learning approach for continuous environments with constraints. The approach combines model-based reinforcement learning with recent advances in approximate optimal control. This results in a bounded-rationality agent that makes decisions in real-time by efficiently solving a sequence of constrained optimization problems on learned sparse Gaussian process models. Such a combination has several advantages. No high-dimensional policy needs to be computed or stored while the learning problem often reduces to a set of lower-dimensional models of the dynamics. In addition, hard constraints can easily be included and objectives can also be changed in real-time to allow for multiple or dynamic tasks. The efficacy of the approach is demonstrated on both an extended cart pole domain and a challenging quadcopter navigation task using real data.

    Download full text (pdf)
    AAAI-2015-Model-Based-Reinforcement
  • 299.
    Andersson, Olov
    et al.
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Ljungqvist, Oskar
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Tiger, Mattias
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Axehill, Daniel
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Heintz, Fredrik
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Receding-Horizon Lattice-based Motion Planning with Dynamic Obstacle Avoidance2018In: 2018 IEEE Conference on Decision and Control (CDC), Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 4467-4474Conference paper (Refereed)
    Abstract [en]

    A key requirement of autonomous vehicles is the capability to safely navigate in their environment. However, outside of controlled environments, safe navigation is a very difficult problem. In particular, the real-world often contains both complex 3D structure, and dynamic obstacles such as people or other vehicles. Dynamic obstacles are particularly challenging, as a principled solution requires planning trajectories with regard to both vehicle dynamics, and the motion of the obstacles. Additionally, the real-time requirements imposed by obstacle motion, coupled with real-world computational limitations, make classical optimality and completeness guarantees difficult to satisfy. We present a unified optimization-based motion planning and control solution, that can navigate in the presence of both static and dynamic obstacles. By combining optimal and receding-horizon control, with temporal multi-resolution lattices, we can precompute optimal motion primitives, and allow real-time planning of physically-feasible trajectories in complex environments with dynamic obstacles. We demonstrate the framework by solving difficult indoor 3D quadcopter navigation scenarios, where it is necessary to plan in time. Including waiting on, and taking detours around, the motions of other people and quadcopters.

    Download full text (pdf)
    Receding-Horizon Lattice-based Motion Planning with Dynamic Obstacle Avoidance
  • 300.
    Andersson, Olov
    et al.
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Sidén, Per
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Arts and Sciences.
    Dahlin, Johan
    Kotte Consulting AB.
    Doherty, Patrick
    Linköping University, Department of Computer and Information Science, Artificial Intelligence and Integrated Computer Systems. Linköping University, Faculty of Science & Engineering.
    Villani, Mattias
    Linköping University, Department of Computer and Information Science, The Division of Statistics and Machine Learning. Linköping University, Faculty of Arts and Sciences. Stockholm University, Stockholm, Sweden.
    Real-Time Robotic Search using Structural Spatial Point Processes2019Conference paper (Refereed)
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