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  • 201.
    Avdic, Kenan
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    On-chip Pipelined Parallel Mergesort on the Intel Single-Chip Cloud Computer2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the advent of mass-market consumer multicore processors, the growing trend in the consumer off-the-shelf general purpose processor industry has moved away from increasing clock frequency as the classical approach for achieving higher performance. This is commonly attributed to the well-known problems of power consumption and heat dissipation with high frequencies and voltage.

    This paradigm shift has prompted research into a relatively new field of "many-core" processors, such as the Intel Single-chip Cloud Computer. The SCC is a concept vehicle, an experimental homogenous architecture employing 48 IA32 cores interconnected by a high-speed communication network.

    As similar multiprocessor systems, such as the Cell Broadband Engine, demonstrate a significantly higher aggregate bandwidth in the interconnect network than in memory, we examine the viability of a pipelined approach to sorting on the Intel SCC. By tailoring an algorithm to the architecture, we investigate whether this is also the case with the SCC and whether employing a pipelining technique alleviates the classical memory bottleneck problem or provides any performance benefits.

    For this purpose, we employ and combine different classic algorithms, most significantly, parallel mergesort and samplesort.

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  • 202.
    Avgouleas, Ioannis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    IoT Networking Resource Allocation and Cooperation2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Internet of Things (IoT) promises that "anything that can be connected, will be connected". It comprises of Information and Communication Technologies that interconnect billions of physical and visual things with some "basic" intelligence. The emerging IoT services will be able to react with minimal human intervention and further contribute to the big data era that requires real-time, ultrareliable, ubiquitous, scalable, and heterogeneous operation.

    This thesis is the result of our investigations on problems dealing with the evolution of such technologies. First, we explore the potential of using relay i.e., intermediate, nodes that assist users to transmit their packets in a a cellular network. Paper I provides insights into how adapting the cooperation of the relay's receiver and transmitter optimizes the network-wide throughput while the relay's queue stability is guaranteed.

    The next part of the thesis copes with the resource allocation of services on IoT devices equipped with multiple network interfaces. The resources are heterogeneous and can be split among dierent interfaces. Additionally, they are not interchangeable. In paper II, we develop optimization models for this resource allocation problem, prove the complexity of the models, and derive results that give intuition into the problems. Moreover, we propose algorithms that approximate the optimal solution and show under which circumstances this is possible.

    Finally, in paper III, we present a resource allocation problem specically for smart cities services. In comparison to the previous problem denition, resources are of one type but the IoT network device can oer capacities that vary over time. Furthermore, services have a tolerance regarding their preferred scheduling, namely, their allocation over time. We parametrize each service with a pricing function to indicate its tolerance to be served at the beginning of the scheduling window. We prove that the problem is computationally hard and provide numerical results to gain insight into how different pricing weight functions impact the allocations' distribution within the scheduling window.

    List of papers
    1. Probabilistic Cooperation of a Full-Duplex Relay in Random Access Networks
    Open this publication in new window or tab >>Probabilistic Cooperation of a Full-Duplex Relay in Random Access Networks
    2017 (English)In: IEEE Access, E-ISSN 2169-3536, Vol. 5, p. 7394-7404Article in journal (Refereed) Published
    Abstract [en]

    In this paper, we analyze the probabilistic cooperation of a full-duplex relay in a multiuser random-access network. The relay is equipped with on/off modes for the receiver and the transmitter independently. These modes are modeled as probabilities by which the receiver and the transmitter are activated. We provide analytical expressions for the performance of the relay queue, such as arrival and service rates, stability conditions, and the average queue size. We optimize the relays operation setup to maximize the network-wide throughput while, simultaneously, we keep the relays queue stable and lower the relays receptions and transmissions. Furthermore, we study the effect of the SINR threshold and the self-interference coefficient on the per-user and network-wide throughput. For low SINR threshold, we show under which circumstances it is beneficial to switch off the relay completely, or switch off the relays receiver only.

    Place, publisher, year, edition, pages
    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017
    Keywords
    Cooperative communication; relays; relay networks; multiaccess communication; multiple access interference; internet of things (IoT); internet; wireless sensor networks (WSNs); body sensor networks (BSNs)
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:liu:diva-139423 (URN)10.1109/ACCESS.2016.2642540 (DOI)000403140800053 ()
    Note

    Funding Agencies|European Union [609094, 612361]

    Available from: 2017-08-07 Created: 2017-08-07 Last updated: 2019-11-08
    2. Allocation of Heterogeneous Resources of an IoT Device to Flexible Services
    Open this publication in new window or tab >>Allocation of Heterogeneous Resources of an IoT Device to Flexible Services
    Show others...
    2016 (English)In: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 3, no 5, p. 691-700Article in journal (Refereed) Published
    Abstract [en]

    Internet-of-Things (IoT) devices can be equipped with multiple heterogeneous network interfaces. An overwhelmingly large amount of services may demand some or all of these interfaces available resources. Herein, we present a precise mathematical formulation of assigning services to interfaces with heterogeneous resources in one or more rounds. For reasonable instance sizes, the presented formulation produces optimal solutions for this computationally hard problem. We prove the NP-completeness of the problem and develop two algorithms to approximate the optimal solution for big instance sizes. The first algorithm allocates the most demanding service requirements first, considering the average cost of interfaces resources. The second one calculates the demanding resource shares and allocates the most demanding of them first by choosing randomly among equally demanding shares. Finally, we provide simulation results giving insight into services splitting over different interfaces for both cases.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    Keywords
    Internet of Things (IoT); mixed integer linear programming; network interfaces; optimization; resource management; scheduling algorithms
    National Category
    Communication Systems
    Identifiers
    urn:nbn:se:liu:diva-135000 (URN)10.1109/JIOT.2016.2535163 (DOI)000393047800006 ()
    Note

    Funding Agencies|Excellence Center at Linkoping-Lund in Information Technology; European Union [324515, 612316, 609094]

    Available from: 2017-03-06 Created: 2017-03-06 Last updated: 2019-11-08Bibliographically approved
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  • 203.
    Axelsson, Jesper
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Implementering av PostgreSQL som databashanterare för MONITOR2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Monitors affärssystem MONITOR är under ständig utveckling och i och med detta ville man kolla upp huruvida PostgreSQL skulle kunna användas som DBMS istället för det nuvarande; Sybase SQL Anywhere. Examensarbete har därför bestått av en jämförelse hur PostgreSQL står sig jämte andra DBMS:er, en implementering utav en PostgreSQLdatabas som MONITOR arbetar mot samt ett prestandatest utav skapandet av databasen.

    I många avseenden verkar PostgreSQL vara ett alternativ till SQL Anywhere;

    1. Alla datatyper finns i båda dialekterna.
    2. Backup av data finns i olika utföranden och går att automatisera
    3. Enkelt att installera och uppdatera.
    4. Ingen licensieringskostnad existerar.
    5. Support finns tillgänglig i olika former.

    Dock så är inte PostgreSQL ett bra DBMS att byta till i dagsläget då systemet inte fungerade på grund av att vissa uttryck inte översattes ordentligt samt att ingen motsvarighet till LIST existerar. Ännu större är dock problemet med tiden det tar att flytta data till en PostgreSQL-databas då det inte är intressant att lösa problem med funktioner i systemet om det ändå inte går att använda på grund utav att konvertering av data tar så lång tid som det gör.

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    fulltext
  • 204.
    Axelsson, Jesper
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Implementering av PostgreSQL som databashanterare för MONITOR2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Monitors affärssystem MONITOR är under ständig utveckling och i och med detta ville man kolla upp huruvida PostgreSQL skulle kunna användas som DBMS istället för det nuvarande; Sybase SQL Anywhere. Examensarbete har därför bestått av en jämförelse hur PostgreSQL står sig jämte andra DBMS:er, en implementering utav en PostgreSQLdatabas som MONITOR arbetar mot samt ett prestandatest utav skapandet av databasen.

    I många avseenden verkar PostgreSQL vara ett alternativ till SQL Anywhere;

    1. Alla datatyper finns i båda dialekterna.
    2. Backup av data finns i olika utföranden och går att automatisera.
    3. Enkelt att installera och uppdatera.
    4. Ingen licensieringskostnad existerar.
    5. Support finns tillgänglig i olika former.

    Dock så är inte PostgreSQL ett bra DBMS att byta till i dagsläget då systemet inte fungerade på grund av att vissa uttryck inte översattes ordentligt samt att ingen motsvarighet till LIST existerar. Ännu större är dock problemet med tiden det tar att flytta data till en PostgreSQL-databas då det inte är intressant att lösa problem med funktioner i systemet om det ändå inte går att använda på grund utav att konvertering av data tar så lång tid som det gör.

    Download full text (pdf)
    fulltext
  • 205.
    Axelsson, Johan
    Linköping University, Department of Computer and Information Science.
    Utveckling av en webbplats i PHP för bilverkstaden Braskens Bro Servicecenter2009Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Jag har utvecklat en prototyp för en webbplats till Braskens Bro Servicecenter (BBS) ett mindre företag inombilverkstadsbranschen. BBS har under en längre tid haft planer på att starta en webbplats för att kunna marknadsföra sig ochförhoppningsvis kunna utöka sin kundkrets. Beslutet togs att inte bara göra en webbplats som fungerar som reklampelare utanäven försöka ge en utökad service för nya och befintliga kunder.

    Att utveckla en webbplats från grunden är ingen enkel uppgift. Det är många val som måste göras och många aspekter som skabeaktas. Denna rapport syftar till att ge läsaren en inblick i de beslut som togs vid utvecklingsarbetet, samt vilka problem dessabeslut var tänkta att lösa. Rapporten ger även en inblick i de funktioner som jag utvecklade specifikt just för att passa en mindrebilverkstad. När man arbetar med webbutveckling, liksom vid all programutveckling är det viktigt att noga tänka över vad somska uppnås med arbetet innan det påbörjas. Man måste specificera bl.a. vilka problem som ska lösas med arbetet, vadwebbplatsen ska innehålla och hur designen ska se ut. Att ha en tydlig specifikation med tydliga mål och krav underlättar arbetetväsentligt. Förutom design och funktionalitet beskriver rapporten även hur jag har arbetat med säkerheten på webbplatsen. Dettaär av stor vikt vid all webbutveckling men framför allt när man har dynamiskt innehåll på sidorna. Att inte skydda databasen kanfå förödande konsekvenser om man har en illasinnad besökare på webbplatsen.

    Arbetet resulterade i en webbplats med inte bara information om företaget och dess verksamhet utan även möjligheten att kunnaboka in tider för verkstadsbesök samt möjlighet att via webbplatsen kunna skicka in frågor om priser m.m. En möjlighet att kunnase sitt fordons aktuella status finns även implementerad.

    Ska man gå vidare med projektet och lägga ut det på nätet som Brasken Bro officiella hemsida krävs att man testar webbplatsenordentligt innan man lanserar den. Vidare kan det även bli aktuellt att designa om vissa delar av webbplatsens layout ochfunktionalitet utifrån den feedback som webbplatsens framtida användare framför.

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    FULLTEXT01
  • 206.
    Axelsson, Nils
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Brunberg, Gustaf
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Larsson, Andreas
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Lööf, Claes
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Sani, Behnam
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Stockman, Peter
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Strömbäck, Filip
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Wennberg, Per
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Utveckling av ett generellt bokningssystem: erfarenheter i projekt i programvaruutveckling2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Rapporten behandlar utvecklandet av ett generellt bokningssystem för att tillåta att användare bokartider hos en kund via en webbsida. Systemet ska också ha stöd för att automatiskt kunna generera faktureringsunderlagför att underlätta kundens administration av bokningar. För att bättre förstå vilkenfunktionalitet ett generellt bokningssystem behöver, har Vikbolandets ryttarförening använts som modellkund.

    Utvecklingen har lett fram till ett generellt bokningssystem som kan anpassas för att ha samma funktionalitetsom det system Vikbolandets ryttarförening tidigare använt sig av. För att undersöka hur generelltresultatet blev diskuteras hur systemet kan användas i andra scenarion.

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    Bokningssystem
  • 207.
    Axling, Erik
    Linköping University, Department of Computer and Information Science.
    Automatic Generation of Simulation Models from Designs2007Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    When working with embedded systems, secure and fast applications are desired. To achieve this the applications needs to be analyzed and optimized so that they will not be deadlocked or communicate inefficiently. For this purpose an analysis program that can track communications, deadlocks and response times is needed. Operating System Embedded, OSE, is a wide spread real-time operating system that is used in embedded systems. OSE-applications are excellent candidates for analysis and there exists such a tool, VirtualTime, for that purpose. To analyze an OSE-application a model needs to be written that VirtualTime can analyze. This takes up time and effort as the models can require a lot of work to write.

    In this thesis we have investigated and implemented a prototype that translates OSE-application code into VirtualTime simulation model code. We used the transformation tool TXL to translate communication and timing behaviors. In the translation one needs to preserve the communication and timing behavior and throw away other unnecessary code in the OSE-application. This complicates the translation and sophisticated methods like backward slicing might be necessary. A proposed method in this thesis could help with the problem.

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    FULLTEXT01
  • 208.
    Azari, Leila
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Domain Specific Modeling Support for ArCon2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One important phase in software development process is to create a design model of the system which follows all the architectural rules. Often the architectural rules are defined by the system architect and the system model is designed by the system designer. The architect defines the rules in a text file where no standard or pattern is followed. Therefore, there is always the risk of violating the architectural rules by the designer. So manual reviews on the system model should be done by the architect to ensure the system model is valid.In order to remove this manual checking which can be erroneous and time consuming ArCon (Architecture Conformance Checker) was developed by Combitech AB. ArCon is a tool which lets the architect define the architectural rules in the format of UML (Unified Modeling Language) models where the elements of the model have different meaning than the standard UML. ArCon can read this model and extract architectural rules from it and check the system model against those rules and then print all the rule violations.ArCon is an open source tool i.e. free for everyone to download and use. Currently, it supports Papyrus as the UML modeling tool. Papyrus is integrated to Eclipse platform and is a general purpose modeling tool. It supports users with all types of UML diagrams and elements.The idea for this thesis work was to implement a new feature for ArCon in order to facilitate the design process for system designers. The feature should provide the system designers only those types of elements which they are permitted to add to a specific fraction of the system model. The list of permitted element types should be extracted from the architecture model where all the architectural rules are defined in advance. This new support in ArCon was named Domain Specific Modeling (DSM) support.To evaluate the effect of DSM support on the system designers performance a few test sessions, called usability tests, were performed. The participants in the test sessions were a representative sample of software designers. After analyzing the data collected from the test sessions, the pros and cons of the new support were discovered. Furthermore, a few new ideas for enhancing DSM support were generated.

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    Leila Azari-Master thesis report
  • 209.
    Aziz Abdulla, Parosh
    et al.
    Uppsala University, Sweden.
    Faouzi Atig, Mohamed
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academic Sinica, Taiwan.
    Phi Diep, Bui
    Uppsala University, Sweden.
    Holik, Lukas
    Brno University of Technology, Czech Republic.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Rummer, Philipp
    Uppsala University, Sweden.
    Flatten and Conquer A Framework for Efficient Analysis of String Constraints2017In: ACM SIGPLAN NOTICES, ACM Press, 2017, Vol. 52, no 6, p. 602-617Conference paper (Refereed)
    Abstract [en]

    We describe a uniform and efficient framework for checking the satisfiability of a large class of string constraints. The framework is based on the observation that both satisfiability and unsatisfiability of common constraints can be demonstrated through witnesses with simple patterns. These patterns are captured using flat automata each of which consists of a sequence of simple loops. We build a Counter-Example Guided Abstraction Refinement (CEGAR) framework which contains both an under-and an over-approximation module. The flow of information between the modules allows to increase the precision in an automatic manner. We have implemented the framework as a tool and performed extensive experimentation that demonstrates both the generality and efficiency of our method.

  • 210.
    Aziz Abdulla, Parosh
    et al.
    Uppsala University, Sweden.
    Haziza, Frederic
    Uppsala University, Sweden.
    Holik, Lukas
    Uppsala University, Sweden; Brno University of Technology, Czech Republic.
    Jonsson, Bengt
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    An integrated specification and verification technique for highly concurrent data structures for highly concurrent data structures2017In: International Journal on Software Tools for Technology Transfer (STTT), ISSN 1433-2779, E-ISSN 1433-2787, Vol. 19, no 5, p. 549-563Article in journal (Refereed)
    Abstract [en]

    We present a technique for automatically verifying safety properties of concurrent programs, in particular programs that rely on subtle dependencies of local states of different threads, such as lock-free implementations of stacks and queues in an environment without garbage collection. Our technique addresses the joint challenges of infinite-state specifications, an unbounded number of threads, and an unbounded heap managed by explicit memory allocation. Our technique builds on the automata-theoretic approach to model checking, in which a specification is given by an automaton that observes the execution of a program and accepts executions that violate the intended specification. We extend this approach by allowing specifications to be given by a class of infinite-state automata. We show how such automata can be used to specify queues, stacks, and other data structures, by extending a data-independence argument. For verification, we develop a shape analysis, which tracks correlations between pairs of threads, and a novel abstraction to make the analysis practical. We have implemented our method and used it to verify programs, some of which have not been verified by any other automatic method before.

  • 211.
    Baburao, Swetha
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Development of a smartphone interface to support the visually impaired.2013Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The World Health Organization (WHO) estimates that 2 billion people in the world will be aged 60 and over by the year 2050. Along with the aging process, there will be declination of sensory, physical and cognitive factors. Vision impairment is a worldwide problem faced by people of all ages. The usage of smartphones has escalated exponentially. Smartphones are now equipped with features like text to speech converters, speech interpreters, voice guided navigation, and intelligent assistants. Appropriately designed, these can be valuable tools for the visually impaired. However, despite the advanced accessibility implemented in the smartphones, the elderly still seems to prefer ordinary phones which have physical buttons. The aim of this thesis was twofold; (1) to identify factors hindering the elderly and their use of smartphones, and (2) to develop smartphone interfaces to improve accessibility.

    Two Android applications were developed in this thesis. The Magnifier is a magnification tool for physical objects and text. EyesFree is a text to speech service that reads out the screen content to the user. The requirements for the apps were elicited by studying existing applications and also by interviewing potential users. EyesFree and Magnifier were evaluated using the think aloud protocol method and the results show that they are useful applications for the visually impaired.

    The Android operating system provides a number of accessibility features and services to help the users with different abilities to navigate the device easily. Paradoxically, these features are quite difficult to use, for example, they are not easily launched and closed. The meta application and user interface of EyesFree exemplifies how users can access the internal features of the OS such as the speech services more effectively.

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    Sweba687_MasterThesis
  • 212. Bachmann, Bernhard
    et al.
    Aronsson, Peter
    Linköping University, Department of Computer and Information Science.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science.
    Robust Initialization of Differential Algebraic Equations2006Conference paper (Refereed)
  • 213.
    Backenhof, Albert
    Linköping University, Department of Science and Technology, Media and Information Technology.
    Automatic Generation of Collision Hulls for Polygonal Objects2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Physics in interactive environments, such as computer games, and simulations require well madeand accurate bounding volumes in order to act both realistically and fast. Today it is common to useeither inaccurate boxes or spheres as bounding volumes or to model the volume by hand. Thesemethods are either too inaccurate or require too much time to ever be able to be used in real-time,accurate virtual environments.This thesis presents a method to automatically generate collision hulls for both manifolds and nonmanifolds.This allows meshes to be used in a physical environment in just a few seconds and stillbeing able to behave realistically. The method performs Approximate Convex Decomposition byiteratively dividing the mesh into smaller, more convex parts. Every part is wrapped in a convexhull. Together the hulls make an accurate, but low cost, convex representation of the original mesh.The convex hulls are stored in a bounding volume hierarchy tree structure that enables fast testingfor collision with the mesh.

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    fulltext
  • 214.
    Backofen, Rolf
    et al.
    Friedrich-Schiller-Universität Jena, Germany.
    Badea, Liviu
    National Institute for Research and Development in Informatics, Bucharest, Romania.
    Barahona, Pedro
    Universidade Nova de Lisboa, Portugal.
    Berndtsson, Mikael
    University of Skövde, Sweden.
    Burger, Albert
    Heriot-Watt University/MRC Human GeneticsUnit, Edinburgh, UK.
    Dawelbait, Gihan
    Technische Universität Dresden, Germany.
    Doms, Andreas
    Technische Universität Dresden, Germany.
    Fages, Francois
    INRIA Rocquencourt, Paris, France.
    Hotaran, Anca
    National Institute for Research and Development in Informatics, Bucharest, Romania.
    Jakoniené, Vaida
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems.
    Krippahl, Ludwig
    Universidade Nova de Lisboa, Portugal.
    Lambrix, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems.
    McLeod, Kenneth
    Heriot-Watt University/MRC Human GeneticsUnit, Edinburgh, UK.
    Nutt, Werner
    Heriot-Watt University/MRC Human GeneticsUnit, Edinburgh, UK.
    Olsson, Bjorn
    University of Skövde, Sweden.
    Schroeder, Michael
    Technische Universität Dresden, Germany.
    Schroiff, Anna
    University of Skövde, Sweden.
    Royer, Luc
    Technische Universität Dresden, Germany.
    Soliman, Sylvain
    INRIA Rocquencourt, Paris, France.
    Tan, He
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems.
    Tilivea, Doina
    National Institute for Research and Development in Informatics, Bucharest, Romania.
    Will, Sebastian
    Friedrich-Schiller-Universit¨at Jena, Germany.
    Requirements and specification of bioinformatics use cases2005Report (Other academic)
  • 215.
    Backofen, Rolf
    et al.
    Friedrich-Schiller-Universität Jena, Germany.
    Badea, Mike
    Victoria University of Manchester, UK.
    Barahona, Pedro
    Universidade Nova de Lisboa, Portugal.
    Badea, Liviu
    National Institute for Research and Development in Informatics, Bucarest, Romania.
    Bry, Francois
    Ludwig-Maximilians-Universität Munchen, Germany.
    Dawelbait, Gihan
    Technical University of Dresden, Germany.
    Doms, Andreas
    Technical University of Dresden, Germany.
    Fages, Francois
    INRIA Rocquencourt, France.
    Goble, Carol
    Victoria University of Manchester, UK.
    Henschel, Andreas
    Technical University of Dresden, Germany.
    Hotaran, Anca
    National Institute for Research and Development in Informatics, Bucarest, Romania.
    Huang, Bingding
    Technical University of Dresden, Germany.
    Krippahl, Ludwig
    Universidade Nova de Lisboa, Portugal.
    Lambrix, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems.
    Nutt, Werner
    Heriot-Watt University, Edinburgh, UK.
    Schroeder, Michael
    Technical University of Dresden, Germany.
    Soliman, Sylvain
    INRIA Rocquencourt, France.
    Will, Sebastian
    Friedrich-Schiller-Universität Jena, Germany.
    Towards a Semantic Web for Bioinformatics2004In: Bioinformatics 2004,2004, 2004, p. 26-26Conference paper (Other academic)
  • 216.
    Backofen, Rolf
    et al.
    Friedrich-Schiller-Universität Jena, Germany.
    Badea, Mike
    Victoria University of Manchester, UK.
    Burger, Albert
    Harriot-Watt University, Edinburgh, UK.
    Fages, Francois
    INRIA Rocquencourt, France.
    Lambrix, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems.
    Nutt, Werner
    Harriot-Watt University, Edinburgh, UK.
    Schroeder, Michael
    Technical University of Dresden, Germany.
    Soliman, Sylvain
    NRIA Rocquencourt, France.
    Will, Sebastian
    Friedrich-Schiller-Universität Jena, Germany.
    State-of-the-art in Bioinformatics2004Report (Other academic)
  • 217.
    Backofen, Rolf
    et al.
    Albert-Ludwigs-universität Freiburg, Germany.
    Burger, Albert
    Heriot-Watt university Edinburgh, UK.
    Busch, Anke
    Albert-Ludwigs-universität Freiburg, Germany.
    Dawelbait, Gihan
    TU Dresden, Germany.
    Fages, Francois
    INRIA Rocquencourt Paris, France.
    Jakoniené, Vaida
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Lambrix, Patrick
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    McLeod, Kenneth
    Heriot-Watt university Edinburgh, UK.
    Soliman, Sylvain
    INRIA Rocquencourt Paris, France.
    Tan, He
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Will, Sebastian
    Albert-Ludwigs-universität Freiburg, Germany.
    Implementation of prototypes2007Report (Other academic)
  • 218.
    Backofen, Rolf
    et al.
    Friedrich-Schiller-Universität Jena, Germany.
    Mike, Badea
    Victoria University of Manchester, UK.
    Barahona, Pedro
    FCT-UNL, Lisbon.
    Burger, Albert
    Harriot-Watt University, Edinburgh, UK.
    Dawelbait, Gihan
    Technical University of Dresden, Germany.
    Doms, Andreas
    Technical University of Dresden, Germany.
    Fages, Francois
    INRIA Rocquencourt, France.
    Hotaran, Anca
    National Institute for Research and Development in Informatics, Romania.
    Jakoniené, Vaida
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems.
    Krippahl, Ludwig
    FCT-UNL, Lisbon.
    Lambrix, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems.
    McLeod, Kenneth
    Harriot-Watt University, Edinburgh, UK.
    Möller, Steffen
    Universität Rostock, Germany.
    Nutt, Werner
    Harriot-Watt University, Edinburgh, UK.
    Olsson, Björn
    University of Skövde, Sweden.
    Schroeder, Michael
    Technical University of Dresden, Germany.
    Soliman, Sylvain
    INRIA Rocquencourt, France.
    Tan, He
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, IISLAB - Laboratory for Intelligent Information Systems.
    Tilivea, Doina
    National Institute for Research and Development in Informatics, Romania.
    Will, Sebastian
    Friedrich-Schiller-Universität Jena, Germany.
    Usage of bioinformatics tools and identification of information sources2005Report (Other academic)
  • 219.
    Bae, Sang Won
    et al.
    Kyonggi University, Suwon, South Korea.
    Korman, Matias
    Tohoku University, Sendai, Japan.
    Mitchell, Joseph SB
    Stony Brook University, New York, USA.
    Okamoto, Yoshio
    The University of Electro-Communications, Tokyo, Japan.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Wang, Haitao
    Utah State University, Utah, USA.
    Computing the $ L_1 $ Geodesic Diameter and Center of a Polygonal Domain2016In: 33rd Symposium on Theoretical Aspects of Computer Science / [ed] Nicolas Ollinger; Heribert Vollmer, Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik , 2016, Vol. 47, p. 14:1-14:14Conference paper (Refereed)
    Abstract [en]

    For a polygonal domain with h holes and a total of n vertices, we present algorithms that compute the L1 geodesic diameter in O(n2+h4) time and the L1 geodesic center in O((n4+n2h4) (n)) time, where (·) denotes the inverse Ackermann function. No algorithms were known for these problems before. For the Euclidean counterpart, the best algorithms compute the geodesic diameter in O(n7.73) or O(n7(h+log n)) time, and compute the geodesic center in O(n12+) time. Therefore, our algorithms are much faster than the algorithms for the Euclidean problems. Our algorithms are based on several interesting observations on L1 shortest paths in polygonal domains.

  • 220.
    Bajracharya, Sudeep
    Linköping University, Department of Computer and Information Science.
    Enhanced OpenModelica Python Interface2016Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    OMPython is a Python library for OpenModelica, which provides a Python interface to OpenModelica. This thesis significantly improves OMPython by an enhanced, more powerful and easier to use API. It presents how a user can use the Python interface to simulate and access Modelica models using Python objects. The enhanced OMPython includes the list of functions that have been implemented such as getXXXNames(), getXXXValues(), setXXXValues(), getXXXOptions(), setXXXOptions(), and simulate(), etc. that allow users to interact with Modelica model properties(i.e., model variables) and the output of the OpenModelica compiler and simulator. A few Modelica models are used for demonstrations in order to make it easy for readers to understand. By the way, this thesis does not describe modeling Modelica models or compilation of such models.

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  • 221.
    Banerjee, Abhijeet
    et al.
    National University of Singapore, Singapore.
    Chattopadhyay, Sudipta
    Saarland University, Saarbrücken, Germany.
    Roychoudhury, Abhik
    National University of Singapore, Singapore.
    On Testing Embedded Software2016In: Advances in Computers, ISSN 0065-2458, Vol. 101, p. 121-153Article in journal (Refereed)
    Abstract [en]

    For the last few decades, embedded systems have expanded their reach into major aspects of human lives. Starting from small handheld devices (such as smartphones) to advanced automotive systems (such as anti-lock braking systems), usage of embedded systems has increased at a dramatic pace. Embedded software are specialized software that are intended to operate on embedded devices. In this chapter, we shall describe the unique challenges associated with testing embedded software. In particular, embedded software are required to satisfy several non-functional constraints, in addition to functionality-related constraints. Such non-functional constraints may include (but not limited to), timing/energy-consumption related constrains or reliability requirements, etc. Additionally, embedded systems are often required to operate in interaction with the physical environment, obtaining their inputs from environmental factors (such as temperature or air pressure). The need to interact with a dynamic, often non-deterministic physical environment, further increases the challenges associated with testing, and validation of embedded software. In the past, testing and validation methodologies have been studied extensively. This chapter, however, explores the advances in software testing methodologies, specifically in the context of embedded software. This chapter introduces the reader to key challenges in testing non-functional properties of software by means of realistic examples. It also presents an easy-to-follow, classification of existing research work on this topic. Finally, the chapter is concluded with a review of promising future directions in the area of embedded software testing.

  • 222.
    Bankler, Hampus
    Linköping University, Department of Computer and Information Science.
    Effektivisering av UI-utveckling i datorspel2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis presents my work at the company Fatshark AB in Stockholm. My supervisor Rikard Blomberg, who works as a chief technology officer at Fatshark and is one of the owners of the company, explained that they had experienced weaknesses in the methodology used when developing heads up displays (HUD) for their games. In the latest production, Lead  and Gold, the HUD had been redesigned a number of times, becoming an unnecessarily big expense due to the number of work hours invested. In modern software development, an iterative workflow is commonly encouraged. Despite this fact, the work efficiency could likely be increased by setting up guidelines as a help in the process of developing HUDs and reviewing the solutions. There was also a need for a way to estimate a particular redesign’s impact on the game before the actual  implementation had been made, and ways to define the pros and cons of each redesign.

    My task was to come up with standards for how the different elements in a UI could be structured and reviewed, in order to improve the developing process of the UI and facilitate the communication between employees. These standards were to be designed by a team consisting of Fatshark employees from different work disciplines and myself.

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  • 223.
    Bao, Min
    et al.
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Andrei, Alexandru
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Eles, Petru Ion
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Peng, Zebo
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Temperature-Aware Task Mapping for Energy Optimization with Dynamic Voltage Scaling2008In: 11th IEEE Workshop on Design and Diagnostics of Electronic Circuits and Systems, 2008, IEEE Computer Society, 2008, p. 44-49Conference paper (Refereed)
    Abstract [en]

    Temperature has become an important issue in nowadays MPSoCs design due to the ever increasing power densities and huge energy consumption. This paper proposes a temperature-aware task mapping technique for energy optimization in systems with dynamic voltage selection capability. It evaluates the efficiency of this technique, based on the analysis of the factors that can influence the potential gains that can be expected from such a technique, compared to a task mapping approach that ignores temperature.

  • 224.
    Bao, Min
    et al.
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Andrei, Alexandru
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Eles, Petru Ion
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Peng, Zebo
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Temperature-Aware Voltage Selection for Energy Optimization2008In: Design, Automation and Test in Europe, 2008, IEEE , 2008, p. 1083-1086Conference paper (Refereed)
    Abstract [en]

    This paper proposes a temperature-aware dynamic voltage selection technique for energy minimization and presents a thorough analysis of the parameters that influence the potential gains that can be expected from such a technique, compared to a voltage selection approach that ignores temperature.

  • 225. Baroglio, Cristina
    et al.
    Bonatti, Piero A.Maluszynski, JanLinköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, TCSLAB - Theoretical Computer Science Laboratory.Marchiori, MassimoPolleres, AxelSchaffert, Sebastian
    Reasoning Web2008Collection (editor) (Other academic)
  • 226.
    Barsomo, Milad
    Linköping University, Department of Computer and Information Science.
    A Survey of Automated Tools for Probing Vulnerable Web Applications2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The development of web applications have increased exceedingly in the last few years. Without the concern of security development, these web applications are exposed to a great amount of cyber threats. This thesis provides a survey of automated tools, or so called black box web scanners, that are used to find vulnerabilities, without any internal knowledge, in a web application. The web scanners was evaluated by running them on an vulnerable web application called XVWA and comparing the scanning results with two criteria. First criterion is to see if it is as accurate as stated, and the second criterion is to check if they pass the requirements of NIST for a web scanner of this type. All of the web scanners included in this thesis are open source/free to use. The results of eight different web scanners shows that most of the scanners does not follow the NIST requirements fully, however the majority still performs well. It has also been seen that the newer and most active developed scanners performs the best which is logical. One of the drawn conclusions is that none works perfect or is above all the other scanners.

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  • 227.
    Barsomo, Milad
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Hurtig, Mats
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Device-aware Adaptation of Websites2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    The use of handheld devices such as smart phones and tablets have exploded in the last few years. These mobile devices differ from regular desktops by having limited battery power, processing power, bandwidth, internal memory, and screen size. With many device types and with mobile adaptation being done in many ways, it is therefore important for websites to adapt to mobile users. This thesis characterise how websites currently are adapting to mobile devices. For our analysis and data collection, we created a tool which sends modified HTTP GET requests that makes the web server believe the GET requests were sent from a smart phone, tablet, or a regular desktop. Another tool then captured all the HTTP packets and let us analyse these for each platform. We chose to analyse the top 500 most popular websites in the world and the top 100 websites from 15 different categories fetched directly from www.alexa.com. Among other things, we observed that of the total HTTP objects fetched to render an average website, mobile or non-mobile, more than half of the objects were images. Another conclusion is that a website fetched by an iPhone 4 device is more heavily reduced in amount of images than a Nexus 7.

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  • 228.
    Basaez, Juan
    et al.
    Linköping University, Department of Computer and Information Science.
    Bergström, Joakim
    Linköping University, Department of Computer and Information Science.
    Fisch, Johan
    Linköping University, Department of Computer and Information Science.
    Ivarsson, Viktor
    Linköping University, Department of Computer and Information Science.
    Magnusson, Oskar
    Linköping University, Department of Computer and Information Science.
    Montelius, Anna
    Linköping University, Department of Computer and Information Science.
    Nodelijk, Felix
    Linköping University, Department of Computer and Information Science.
    Plattform för visualisering av trafikdata2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Den här rapporten redovisar och diskuterar resultatet av ett kandidatarbete. Arbetet som utförts var uppdraget Plattform för maskininlärning och visualisering av trafikdata med Institutionen för datavetenskap som kund och Östgötatrafiken som behovsägare och referenspartner. Östgötatrafiken är idag intresserade av maskininlärningsmöjligheter inom trafikområdet och efterfrågar en plattform som möjliggör presentation samt analys av trafikdata med hjälp av maskininlärning. Uppdragets syfte var att utveckla en produkt som passade Östgötatrafikens önskemål för att visualisera trafikdata i Linköping och Norrköping. Projektet utfördes av sju studenter som studerade på Linköpings universitet som en del av kursen TDDD96 Kandidatprojekt i programvaruutveckling och resulterade i webbapplikationen Chronos. Chronos är ett system byggt enligt en treskiktad klient-server-arkitektur där klienten är en webbsida byggd i JavaScript med React och servern är byggd i Python med Flask och Flask-SQLAlchemy. Klienten har kontroller för filtrering av data och visualisering av trafikdata sker på en Leaflet-karta. De data som visualiseras på kartan hämtas automatiskt från Trafiklab, som tillhandahåller API:er för kollektivtrafiken i Sverige, för att bygga en databas med historisk trafikdata. Visualisering av data sker genom att visa bilder av bussarnas hastigheter över en vald tidsperiod. Rapporten innehåller även individuella bidrag från varje gruppmedlem.

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  • 229.
    Basile, Maurizio
    et al.
    Linköping University, Department of Computer and Information Science.
    Raciti, Massimiliano Gabriele
    Linköping University, Department of Computer and Information Science.
    A Cloud-Based Execution Environment for a Pandemic Simulator2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis is to develop a flexible distributed platform designed toexecute a disease outbreaks simulator in a fast way over many types of platformsand operating systems. The architecture is realized using the Elastic ComputeCloud (EC2) supplied by Amazon and Condor as middleware among the varioustypes of OS. The second part of the report describes the realization of a webapplication that allows users to manage easily the various part of the architecture,to launch the simulations and to view some statistics of the relative results.

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  • 230.
    Bavelski, Alexei
    Linköping University, Department of Computer and Information Science.
    On the Performance of the Solaris Operating System under the Xen Security-enabled Hypervisor2007Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis presents an evaluation of the Solaris version of the Xen virtual machine monitor and a comparison of its performance to the performance of Solaris Containers under similar conditions. Xen is a virtual machine monitor, based on the paravirtualization approach, which provides an instruction set different to the native machine environment and therefore requires modifications to the guest operating systems. Solaris Zones is an operating system-level virtualization technology that is part of the Solaris OS. Furthermore, we provide a basic performance evaluation of the security modules for Xen and Zones, known as sHype and Solaris Trusted Extensions, respectively.

    We evaluate the control domain (know as Domain-0) and the user domain performance as the number of user domains increases. Testing Domain-0 with an increasing number of user domains allows us to evaluate how much overhead virtual operating systems impose in the idle state and how their number influences the overall system performance. Testing one user domain and increasing the number of idle domains allows us to evaluate how the number of domains influences operating system performance. Testing concurrently loaded increasing numbers of user domains we investigate total system efficiency and load balancing dependent on the number of running systems.

    System performance was limited by CPU, memory, and hard drive characteristics. In the case of CPU-bound tests Xen exhibited performance close to the performance of Zones and to the native Solaris performance, loosing 2-3% due to the virtualization overhead. In case of memory-bound and hard drive-bound tests Xen showed 5 to 10 times worse performance.

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  • 231.
    Bednarski, Andrzej
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    A dynamic programming approach to optimal retargetable code generation for irregular architectures2002Licentiate thesis, monograph (Other academic)
    Abstract [en]

    In this thesis we address the problem of optimal code generation for irregular architectures such as Digital Signal Processors (DSPs). Code generation consists mainly of three tasks: instruction selection, instruction scheduling and register allocation. These tasks have been discovered to be NP-difficult for most of the architectures and most situations.

    A common approach to code generation consists in solving each task separately, i.e. in a decoupled manner, which is easier from an engineering point of view. Decoupled phase based compilers produce good code quality for regular architectures, but if applied to DSPs the resulting code is of significantly lower performance due to strong interdependencies between the different tasks.

    We report on a novel method for fully integrated code generation based on dynamic programming. It handles the most important tasks of code generation in a single optimization step and produces optimal code sequence. Our dynamic programming algorithm is applicable to small, yet not trivial problem instances with up to 50 instructions per basic block if data locality is not an issue, and up to 20 instructions if we take data locality on irregular processor architectures into account.

    In order to obtain a retargetable framework we developed a first version of a structured hardware description language, ADML, which is based on XML. We implemented a prototype framework of such a retargetable system for optimal code generation.

    As far as we know from the literature, this is the first time that the main tasks of code generation are solved optimally in a single and fully integrated optimization step that additionally considers data placement in registers. 

  • 232. Order onlineBuy this publication >>
    Bednarski, Andrzej
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    Integrated Optimal Code Generation for Digital Signal Processors2006Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In this thesis we address the problem of optimal code generation for irregular architectures such as Digital Signal Processors (DSPs).

    Code generation consists mainly of three interrelated optimization tasks: instruction selection (with resource allocation), instruction scheduling and register allocation. These tasks have been discovered to be NP-hard for most architectures and most situations. A common approach to code generation consists in solving each task separately, i.e. in a decoupled manner, which is easier from a software engineering point of view. Phase-decoupled compilers produce good code quality for regular architectures, but if applied to DSPs the resulting code is of significantly lower performance due to strong interdependences between the different tasks.

    We developed a novel method for fully integrated code generation at the basic block level, based on dynamic programming. It handles the most important tasks of code generation in a single optimization step and produces an optimal code sequence. Our dynamic programming algorithm is applicable to small, yet not trivial problem instances with up to 50 instructions per basic block if data locality is not an issue, and up to 20 instructions if we take data locality with optimal scheduling of data transfers on irregular processor architectures into account. For larger problem instances we have developed heuristic relaxations.

    In order to obtain a retargetable framework we developed a structured architecture specification language, xADML, which is based on XML. We implemented such a framework, called OPTIMIST that is parameterized by an xADML architecture specification.

    The thesis further provides an Integer Linear Programming formulation of fully integrated optimal code generation for VLIW architectures with a homogeneous register file. Where it terminates successfully, the ILP-based optimizer mostly works faster than the dynamic programming approach; on the other hand, it fails for several larger examples where dynamic programming still provides a solution. Hence, the two approaches complement each other. In particular, we show how the dynamic programming approach can be used to precondition the ILP formulation.

    As far as we know from the literature, this is for the first time that the main tasks of code generation are solved optimally in a single and fully integrated optimization step that additionally considers data placement in register sets and optimal scheduling of data transfers between different registers sets.

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  • 233.
    Bednarski, Andrzej
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Kessler, Christoph
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Energy-Optimal Integrated VLIW Code Generation2004In: CPC04 11th Int. Workshop on Compilers for Parallel Computers,2004, 2004, p. 227-238Conference paper (Other academic)
  • 234.
    Bednarski, Andrzej
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Kessler, Christoph
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Exploiting Symmetries for Optimal Integrated Code Generation2004In: Int. Conf. on Embedded Systems and Applications ESA04,2004, 2004Conference paper (Refereed)
  • 235.
    Bednarski, Andrzej
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Kessler, Christoph
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Integer Linear Programming versus Dynamic Programming for Optimal Integrated VLIW Code Generation2006In: 12th Int. Workshop on Compilers for Parallel Computers,2006, 2006, p. 73-Conference paper (Refereed)
  • 236.
    Bendtsen, Marcus
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Bayesian Optimisation of Gated Bayesian Networks for Algorithmic Trading2015In: / [ed] John Mark Agosta, Rommel Novaes Carvalho, CEUR-WS.org , 2015, Vol. 1565, p. 2-11Conference paper (Refereed)
    Abstract [en]

    Gated Bayesian networks (GBNs) are an extension of Bayesian networks that aim to model systems that have distinct phases. In this paper, we aim to use GBNs to output buy and sell decisions for use in algorithmic trading systems. These systems may have several parameters that require tuning, and assessing the performance of these systems as a function of their parameters cannot be expressed in closed form, and thus requires simulation. Bayesian optimisation has grown in popularity as a means of global optimisation of parameters where the objective function may be costly or a black box. We show how algorithmic trading using GBNs, supported by Bayesian optimisation, can lower risk towards invested capital, while at the same time generating similar or better rewards, compared to the benchmark investment strategy buy-and-hold.

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  • 237. Order onlineBuy this publication >>
    Bendtsen, Marcus
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Gated Bayesian Networks2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Bayesian networks have grown to become a dominant type of model within the domain of probabilistic graphical models. Not only do they empower users with a graphical means for describing the relationships among random variables, but they also allow for (potentially) fewer parameters to estimate, and enable more efficient inference. The random variables and the relationships among them decide the structure of the directed acyclic graph that represents the Bayesian network. It is the stasis over time of these two components that we question in this thesis.

    By introducing a new type of probabilistic graphical model, which we call gated Bayesian networks, we allow for the variables that we include in our model, and the relationships among them, to change overtime. We introduce algorithms that can learn gated Bayesian networks that use different variables at different times, required due to the process which we are modelling going through distinct phases. We evaluate the efficacy of these algorithms within the domain of algorithmic trading, showing how the learnt gated Bayesian networks can improve upon a passive approach to trading. We also introduce algorithms that detect changes in the relationships among the random variables, allowing us to create a model that consists of several Bayesian networks, thereby revealing changes and the structure by which these changes occur. The resulting models can be used to detect the currently most appropriate Bayesian network, and we show their use in real-world examples from both the domain of sports analytics and finance.

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  • 238.
    Bendtsen, Marcus
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Regimes in baseball players' career data2017In: Data mining and knowledge discovery, ISSN 1384-5810, E-ISSN 1573-756X, Vol. 31, no 6, p. 1580-1621Article in journal (Refereed)
    Abstract [en]

    In this paper we investigate how we can use gated Bayesian networks, a type of probabilistic graphical model, to represent regimes in baseball players’ career data. We find that baseball players do indeed go through different regimes throughout their career, where each regime can be associated with a certain level of performance. We show that some of the transitions between regimes happen in conjunction with major events in the players’ career, such as being traded or injured, but that some transitions cannot be explained by such events. The resulting model is a tool for managers and coaches that can be used to identify where transitions have occurred, as well as an online monitoring tool to detect which regime the player currently is in.

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  • 239.
    Bendtsen, Marcus
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Peña, Jose M.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Gated Bayesian Networks2013In: TWELFTH SCANDINAVIAN CONFERENCE ON ARTIFICIAL INTELLIGENCE (SCAI 2013), Amsterdam: IOS Press, 2013, p. 35-44Conference paper (Refereed)
    Abstract [en]

    This paper introduces a new probabilistic graphical model called gated Bayesian network (GBN). This model evolved from the need to represent real world processes that include several distinct phases. In essence a GBN is a model that combines several Bayesian networks (BN) in such a manner that they may be active or inactive during queries to the model. We use objects called gates to combine BNs, and to activate and deactivate them when predefined logical statements are satisfied. These statements are based on combinations of posterior probabilities of the variables in the BNs. Although GBN is a new formalism there are features of GBNs that are similar to other formalisms and research, including influence diagrams, context-specific independence and structural adaptation.

  • 240.
    Bendtsen, Marcus
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Peña, Jose M.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Gated Bayesian Networks for Algorithmic Trading2016In: International Journal of Approximate Reasoning, ISSN 0888-613X, E-ISSN 1873-4731, Vol. 69, p. 58-80Article in journal (Refereed)
    Abstract [en]

    Gated Bayesian networks (GBNs) are a recently introduced extension of Bayesian networks that aims to model dynamical systems consisting of several distinct phases. In this paper, we present an algorithm for semi-automatic learning of GBNs. We use the algorithm to learn GBNs that output buy and sell decisions for use in algorithmic trading systems. We show how using the learnt GBNs can substantially lower risks towards invested capital, while at the same time generating similar or better rewards, compared to the benchmark investment strategy buy-and-hold.

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  • 241.
    Bendtsen, Marcus
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Peña, Jose M.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, The Institute of Technology.
    Learning Gated Bayesian Networks for Algorithmic Trading2014In: Probabilistic Graphical Models: 7th European Workshop, PGM 2014, Utrecht, The Netherlands, September 17-19, 2014. Proceedings / [ed] Linda C. van der Gaag and Ad J. Feelders, Springer, 2014, p. 49-64Conference paper (Refereed)
    Abstract [en]

    Gated Bayesian networks (GBNs) are a recently introduced extension of Bayesian networks that aims to model dynamical systems consisting of several distinct phases. In this paper, we present an algo- rithm for semi-automatic learning of GBNs. We use the algorithm to learn GBNs that output buy and sell decisions for use in algorithmic trading systems. We show how using the learnt GBNs can substantially lower risks towards invested capital, while at the same time generating similar or better rewards, compared to the benchmark investment strat- egy buy-and-hold. 

  • 242.
    Bendtsen, Marcus
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Peña, Jose M.
    Linköping University, Department of Computer and Information Science, Statistics. Linköping University, Faculty of Science & Engineering.
    Modelling regimes with Bayesian network mixtures2017In: Proceedings of the 30th Annual Workshop of the Swedish Artificial Intelligence Society SAIS 2017, May 15–16, 2017, Karlskrona, Sweden / [ed] Niklas Lavesson, Linköping: Linköping University Electronic Press, 2017, Vol. 137, p. 20-29, article id 002Conference paper (Refereed)
    Abstract [en]

    Bayesian networks (BNs) are advantageous when representing single independence models, however they do not allow us to model changes among the relationships of the random variables over time. Due to such regime changes, it may be necessary to use different BNs at different times in order to have an appropriate model over the random variables. In this paper we propose two extensions to the traditional hidden Markov model, allowing us to represent both the different regimes using different BNs, and potential driving forces behind the regime changes, by modelling potential dependence between state transitions and some observable variables. We show how expectation maximisation can be used to learn the parameters of the proposed model, and run both synthetic and real-world experiments to show the model’s potential.

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    Modelling regimes with Bayesian network mixtures
  • 243.
    Bengtson, John
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Jigin, Ola
    Linköping University, Department of Computer and Information Science. Linköping University, Faculty of Science & Engineering.
    Increasing the availability of a service through Hot Passive Replication2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor thesis examines how redundancy is used to tolerate a process crash fault on a server in a system developed for emergency situations. The goal is to increase the availability of the service the system delivers. The redundant solution uses hot passive replication with one primary replica manager and one backup replica manager. With this approach, code for updating the backup, code for establishing a new primary and code to implement fault detection to detect a process crash has been written. After implementing the redundancy, the redundant solution has been evaluated. The first part of the evaluation showed that the redundant solution can deliver a service in case of a process crash on the primary replica manager. The second part of the evaluation showed that the average response time for an upload request and a download request had increased by 31\% compared to the non-redundant solution. The standard deviation was calculated for the response times and it showed that the response time of an upload request could be higher compared to the average response time. This large deviation has been investigated and the conclusion was that the database insertion was the reason.

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  • 244.
    Bengtsson, Fredrik
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Combler, Adam
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Automatic Dispatching of Issues using Machine Learning2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Many software companies use issue tracking systems to organize their work. However, when working on large projects, across multiple teams, a problem of finding the correctteam to solve a certain issue arises. One team might detect a problem, which must be solved by another team. This can take time from employees tasked with finding the correct team and automating the dispatching of these issues can have large benefits for the company. In this thesis, the use of machine learning methods, mainly convolutional neural networks (CNN) for text classification, has been applied to this problem. For natural language processing both word- and character-level representations are commonly used. The results in this thesis suggests that the CNN learns different information based on whether word- or character-level representation is used. Furthermore, it was concluded that the CNN models performed on similar levels as the classical Support Vector Machine for this task. When compared to a human expert, working with dispatching issues, the best CNN model performed on a similar level when given the same information. The high throughput of a computer model, therefore, suggests automation of this task is very much possible.

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    Automatic Dispatching of Issues using Machine Learning
  • 245.
    Bengtsson, Jonna
    Linköping University, Department of Electrical Engineering.
    Scenario-Based Evaluation of a Method for System Security Assessment2005Independent thesis Basic level (professional degree), 10 points / 15 hpStudent thesis
    Abstract [en]

    This thesis evaluates a method for system security assessment (MASS), developed at the Swedish Defence Research Agency in Linköping. The evaluation has been carried out with the use of scenarios, consisting of three example networks and several modifications of those. The results from the scenarios are then compared to the expectations of the author and a general discussion is taken about whether or not the results are realistic.

    The evaluation is not meant to be exhaustive, so even if MASS had passed the evaluation with flying colors, it could not have been regarded as proof that the method works as intended. However, this was not the case; even though MASS responded well to the majority of the modifications, some issues indicating possible adjustments or improvements were found and commented on in this report.

    The conclusion from the evaluation is therefore that there are issues to be solved and that the evaluated version of MASS is not ready to be used to evaluate real networks. The method has enough promise not to be discarded, though. With the aid of the issues found in this thesis, it should be developed further, along with the supporting tools, and be re-evaluated.

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  • 246.
    Bengtsson, Tomas
    et al.
    Jönköping University, Sweden.
    Jutman, Artur
    Tallinn University of Technology, Estonia.
    Kumar, Shashi
    Jönköping University, Sweden.
    Ubar, Raimund
    Tallinn University of Technology, Estonia.
    Peng, Zebo
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Off-line Testing of Delay Faults in NoC Interconnects2006In: 9th EUROMICRO Conference on Digital System Design: Architectures, Methods and Tools, 2006, IEEE Computer Society, 2006, p. 677-680Conference paper (Refereed)
    Abstract [en]

    Testing of high density SoCs operating at high clock speeds in an important but difficult problem. Many faults, like delay faults, in such sub-micron chips may only appear when the chip works at normal operating speed. In this paper, we propose a methodology for at-speed testing of delay faults in links connecting two distinct clock domains in a SoC. We give an analytical analysis about the efficiency of this method. We also propose a simple digital hardware structure for the receiver end of the link under test to detect delay faults. It is possible to extend our method to combine it with functional testing of the link and adapt it for on-line testing.

  • 247.
    Bengtsson, Åke
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Utvärdering och implementering av administrationsgränssnitt för säkerhets- och integrationsplattformen CESP2011Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [sv]

    Cybercom Group AB har en kombinerad säkerhets- och integrationsplattform kallad CESP, Cybercom Enhanced Security Platform. I CESP finns bl.a. en autentiseringstjänst, åtkomstkontroll, loggning och logganalys. Det finns även ett webbaserat administrationsgränssnitt för att komma åt och administrera tjänsterna.

    Examensarbetet har gått ut på att utvärdera och omforma adminis-trationsgränssnittet för att göra gränssnittet mer enhetligt och lättarbetat. Examensarbetet har varit inriktat på att ge utvecklarna ett stöd för vidare utveckling med fokus på användbarhet och avslutades med en utvärdering mellan den »gamla« och »nya« administrationsportalen.

    Examensrapporten kommer ta upp hela arbetsprocessen indelat i dess fyra faser; undersökning, design, implementation och utvärdering.

    Examensarbetet har lett till en implementation av en begränsad del i en administrationsportal samt en omfattande pappersprototyp som visar hur en vidare implementation av administrationsportalen kan se ut. Resultatet av utvärderingen visade inte på någon signifikant skillnad mellan den »gamla« och »nya« administrationsportalen, detta till stor del p.g.a. felaktigt val av utvärderingsmetod som inte var lämpad att utvärdera två olika system.

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  • 248.
    Berg, Emil
    Linköping University, Department of Computer and Information Science, Software and Systems.
    Ad-hoc Routing in Low Bandwidth Environments2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    AODV (Ad hoc On-demand Distance Vector routing), DSDV (Destination-Sequenced Distance-Vector routing), DSR (Dynamic Source Routing), and OLSR (Optimized Link State Routing protocol) are protocols used for routing management in ad-hoc networks. In a specific sensor data network application, nodes need information about the network topology, i.e. the network nodes and the connections between them. OLSR provides nodes with this information, while the three other protocols do not. This thesis investigates how OLSR compares to AODV, DSDV,and DSR in a low bandwidth network scenario. Two cases were analyzed: One where AODV, DSDV, and DSR distribute topology information in the application layer and one where they do not.

    The sensor data application was not finished when this thesis project started. Instead, a simplified traffic model of the application was used. In addition to a protocol comparison, this thesis investigates if traffic generated from the model results in high rates of packet loss, assuming low bandwidth conditions. The ns-3 network simulator was used for these investigations.

    This thesis shows that AODV outperforms the three other protocols regardless of whether AODV, DSDV, and DSR distribute topology information in the application layer or not. Furthermore, it is shown that running the traffic model in the low bandwidth environment is not possible without high rates of packet loss.

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  • 249. Berg, Karin
    et al.
    Nyström, Kaj
    Linköping University, The Institute of Technology. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Hydrological Modeling in Modelica2005In: 4th International Modelica Conference, March 2005,2005, 2005Conference paper (Other academic)
  • 250.
    Bergbom, Mattias
    Linköping University, Department of Science and Technology.
    Super-Helices for Hair Modeling and Dynamics2007Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    We present core components of a hair modeling and dynamics solution for the feature film industry. Recent research results in hair simulation are exploited as a dynamics model based on solving the Euler-Lagrange equations of motion for a discretized Cosserat curve is implemented in its entirety. Solutions to the dynamics equations are derived and a framework for symbolic integration is outlined. The resulting system is not unconditionally positive definite but requires balanced physical parameters in order to be solvable using a regular linear solver. Several implementation examples are presented, as well as a novel modeling technique based on non-linear optimization.

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