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  • 251.
    Fouladi, Amir Hossein
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Zafari Khorvaj, Omid
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    TryMyLanguage: An Extensible, Web-based Software Development Environment2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Introducing a new programming language can be a challenge to languagedesigners and developers. This is usually due to diculties related to settingup the environment and going through the documentation for people whowant to start using and learning the language. In this thesis, we developeda web-based software system called TryMyLanguage which can be used toalleviate this issue by eliminating the need for users to install and congurerelated software tools such as compiler, interpreter, etc., on their computers.TryMyLanguage can be congured with dierent programming languagesand it is not limited to a set of predened languages. We evaluated thesystem by simulating a production environment and showing how it wouldbehave in such an environment. At the end a case study is presented to showhow the system can be used with a programming language named Modelyzeas an example.

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  • 252.
    French, Kimberley
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Energy Consumption of In-Vehicle Communication in Electric Vehicles: A comparison between CAN, Ethernet and EEE2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    As a step towards decreasing the greenhouse gas emissions caused by the transport sector, electrical vehicles (EVs) have become more and more popular. Two major problem areas the EV industry is currently facing are range limitations, i.e. being restricted by the capacity of the battery, as well as a demand for higher bandwidth as the in-vehicle communication increases. In this thesis, an attempt is made to address these problem areas by examining the energy consumption required by Controller Area Network (CAN) and Ethernet. In addition, the effects of Energy-Efficient Ethernet (EEE) are reviewed. The protocols are examined by performing a theoretical analysis over CAN, Ethernet and EEE, physical tests over CAN and Ethernet, as well as simulations of EEE. The results show that Ethernet requires 2.5 to four times more energy than CAN in theory, and 4.5 to six times more based on physical measurements. The energy consumption of EEE depends on usage, ranging from energy levels of 40 \% less than CAN when idle, and up to equal amounts as regular Ethernet at high utilisation. By taking full advantage of the traits of Time-Sensitive Networking, EEE has the potential of significantly decreasing the amount of energy consumed compared to standard Ethernet while still providing a much higher bandwidth than CAN, at the cost of introducing short delays. This thesis provides insight into the behaviour of a transmitter for each of the three protocols, discusses the energy implications of replacing CAN with Ethernet and highlights the importance of understanding how to use Ethernet and EEE efficiently.

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  • 253.
    Fridell, Emil
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Architectural Rules Conformance with ArCon and Open-SourceModeling Tools2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In software development it is often crucial that the system implementationfollows the architecture dened through design patterns and a constraint set.In Model-Driven development most artefacts are created using models, butthe architectural design rules is one area where no standard to model therules exists. ArCon, Architecture Conformance Checker, is a tool to checkconformance of architectural design rules on a system model, dened in UML,that implements the system or application. The architectural design rules aredened in a UML model but with a specic meaning, dierent from standardUML, proposed by the authors of ArCon. Within this thesis ArCon wasextended to be able to check models created by the Open-Source modelingtool Papyrus, and integrated as a plugin on the Eclipse platform. The methodused by ArCon, to dene architectural rules, was also given a short evaluationduring the project to get a hint of its potential and future use. The case-studyshowed some problems and potential improvements of the used implementationof ArCon and its supported method.

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  • 254.
    Frimodig, Johan
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Utvärdering och förslag för att skapa ett effektivare administrationsverktyg i AES2018Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta arbete har som syfte att visa vad administrationsverktyget i Authentic Examination System kan förbättra för att uppnå högre effektivitet. För att hitta vad som kan förbättras utifrån effektivitet har metoden Think a loud använts tillsammans med mätvärden som ofta används för att mäta effektivitet. En prototyp har också utvecklats där hänsyn har tagits till de delar som hittats under analysen av administrationsverktyget. Prototypen och administrationsverktyget har sedan jämförts för att se hur de potentiella förbättringar som implementerats i prototypen påverkat effektiviteten. Slutligen sammanställs ettresultat som pekar på vad som kan effektiviseras i administrationsverktyget.

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  • 255.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Urquía Moraleda, Alfonso (Översättare)
    Universidad Nacional de Educación a Distancia, Madrid, España.
    Villa Ramírez, José Luis (Översättare)
    Campus Tecnológico Km 1, Via Turbaco Cartagena de Indias, Colombia.
    Introducción al Modelado y Simulación de Sistemas Técnicos y Físicos con Modelica2015Bok (Övrigt vetenskapligt)
    Abstract [es]

    Domine el modelamiento y simulación usando Modelica, el nuevo poderoso y altamente versátil lenguaje de modelamiento basado en objetos.

    Modelica, el nuevo lenguaje de modelamiento de software/hardware orientado a objetos que está ganando una rápida popularidad en el mundo entero, ofrece un acercamiento casi universal al modelamiento y simulación computacional de alto nivel. Modelica maneja un amplio rango de dominios de aplicación, por ejemplo, sistemas mecánicos, eléctricos, de control, y termodinámicos, y facilita el uso de notación general así como el uso de poderosas abstracciones e implementaciones eficientes. Usando el versátil lenguaje de Modelica y su tecnología asociada, este texto presenta un acercamiento orientado a objetos basado en componentes que le hace posible a los lectores dominar rápidamente las bases del modelamiento matemático basado en ecuaciones orientado a objetos (EOO por sus siglas en inglés) y simulación soportado por computadora.

    A través de este texto Modelica se usa para ilustrar los diferentes aspectos del modelamiento y la simulación. A la vez, se explican varios conceptos claves del lenguaje Modelica con el uso de ejemplos de modelamiento y simulación. Este libro:

    • Examina los conceptos básicos tales como sistemas, modelos y simulaciones
    • Guía al lector a través del lenguaje Modelica con la ayuda de varios ejemplos paso a paso
    • Introduce el concepto de la clase Modelica y su uso en el modelamiento gráfico y basado en texto.
    • Explora las metodologías de modelamiento para sistemas continuos, discretos e híbridos
    • Presenta una revisión de la Librería Estándar de Modelica y las librerías clave de modelos de Modelica

    Los lectores encontrarán una buena cantidad de ejemplos de modelos que simulan aplicaciones en distintos dominios así como ejemplos que combinan varios dominios. Todos los ejemplos y ejercicios en el texto están disponibles a través de DrModelica. Este programa de auto enseñanza electrónico, disponible gratuitamente en el sitio web  que acompaña al texto, guía a los lectores desde ejemplos introductorios y simples hasta ejercicios mas avanzados.

    Escrito por el Director del consorcio Open Source Modelica Consortium, Introducción al Modelamiento y Simulación de Sistemas Físicos y Técnicos con Modelica es un libro recomendado para ingenieros y estudiantes interesados en el diseño, modelamiento, simulación y análisis asistido por computador de sistemas técnicos y naturales. Partiendo de conceptos básicos, el texto es ideal para estudiantes quienes desean aprender del modelamiento y la simulación orientado a objetos.

    Este libro está enfocado en la enseñanza del modelamiento y simulación usando Modelica para principiantes, o en cursos donde hay limitado espacio de tiempo para una introducción a Modelica. Para un cubrimiento con mayor profundidad de este tópico se recomienda el libro Principles of Object-Oriented Modeling and Simulation with Modelica 3.3: A Cyber-Physical Approach, el cual también incluye el material introductorio de este libro.

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    Introducción al Modelado y Simulación de Sistemas Técnicos y Físicos con Modelica
  • 256.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Model-based development of sustainable cyber-physical systems including requirement formalization using the OpenModelica Model-based Development Toolkit2016Ingår i: ACM PROCCEDINGS OF THE 10TH EUROPEAN CONFERENCE ON SOFTWARE ARCHITECTURE WORKSHOPS (ECSA-W), ASSOC COMPUTING MACHINERY , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Large-scale and increasingly software-defined systems in power and factory automation are very long-lived. Longevity requires sustainability-economically, environmentally and last but not least in terms of usability. Sustainability therefore requires continuous change. In this talk we look at handling requirements, models, and implementations in a model-driven formal way that lends itself to a more systematic change tracking than traditional software development approaches and languages, but that also crosses boundaries of software-controlled physical equipment models (so-called cyber-physical systems), distributed digital control (networked systems) and software services. The industry is currently seeing a rapid development of cyber-physical system products. The systems that are developed have increasing demands of sustainability, dependability and usability. Moreover, lead time and cost efficiency continue to be essential for industry competitiveness. Extensive use of modeling and simulation - Model-Based Systems Engineering (MBSE) tools - throughout the value chain and system life-cycle is one of the most important ways to effectively target these challenges. Simultaneously there is an increased interest in open source tools that allow more control of tool features and support, and increased cooperation and shared access to knowledge and innovations between organizations. In this talk we briefly present technology and open source tooling for MBSE based on the Modelica and UML standards, supported by tools such as OpenModelica and Papyrus respectively. Modelica is a modern, strongly typed, declarative, equation-based, and object-oriented language for modeling and simulation of complex cyber-physical systems, whereas UML is a wide-spread industrial standard for software modeling. We present the OpenModelica open source MBSE environment including the ModelicaML Eclipse plug-in integrating Modelica and UML, covering the development process starting from business processes, via requirements, to models, which can be compiled to simulations or to product code. An important question is whether a particular system design fulfills or violates requirements that are imposed on the system under development. We give examples of case studies starting with natural-language requirements and show briefly how they are translated into models. Then, designs and verification scenarios are modeled, and simulation models are composed and simulated automatically. The simulation results produced can then be used to draw conclusions on requirement fulfillment. Other features of the environment are meta modeling for efficient model transformations, the Functional Mockup Interface for general tool integration, model-based optimization, as well as generation of parallel code for multi-core architectures.

  • 257.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Principles of object-oriented modeling and simulation with Modelica 3.3: a cyber-physical approach2015 (uppl. 2)Bok (Övrigt vetenskapligt)
    Abstract [en]

    The second edition features improvements and updates of the Modelica language including synchronous clocked constructs, examines basic concepts of cyber-physical, equation-based, object-oriented system modeling and simulation. Prof. Fritzson introduces the Modelica class concept and its use in graphical and textual modeling with several hundred examples from many application areas and explores modeling methodology for continuous, discrete, and hybrid systems; and more.

    This text is aimed at System Modeling and Simulation engineers, control engineers, mechanical engineers, those working with CAD (Computer Aided Design), virtual reality, biochemistry, embedded systems, and data communication.

    Fritzson covers the Modelica language in impressive depth from the basic concepts such as cyber-physical, equation-base, object-oriented, system, model, and simulation, while also incorporating over a hundred exercises and their solutions for a tutorial, easy-to-read experience.

    • The only book with complete Modelica 3.3 coverage
    • Over one hundred exercises and solutions
    • Examines basic concepts such as cyber-physical, equation-based, object-oriented, system, model, and simulation

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  • 258.
    Fritzson, Peter
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Elmqvist, HildingDassault Systémes AB, Sweden.
    Proceedings of the 11th International Modelica Conference, Versailles, France, September 21-23, 20152015Proceedings (redaktörskap) (Refereegranskat)
    Abstract [en]

    Welcome The 11th International Modelica Conference, which takes place at Palais des Congrès de Versailles, is the main event for the Modelica community. Users, library developers, tool vendors, and language designers gather to share their knowledge and learn about the latest scientific and industrial progress related to Modelica and FMI (Functional Mockup Interface). The fundamental idea behind Modelica is to allow storing modeling knowhow in a high-level formally defined format, i.e., to collect information which you otherwise would find in engineering books only accessible by humans. By allowing convenient reuse of this knowhow by definition of component model libraries, enormous saving in man-hours for setting up simulation studies is achieved. Furthermore, by proper validation of such model libraries, much more reliable conclusions can be made from simulation studies leading to better products and user experience. These considerations lead to the equation-based object-oriented formalism of Modelica. Since the start of the collaborative design work for Modelica in 1996, Modelica has matured from an idea among a small number of dedicated enthusiasts to a widely accepted standard language for the modeling and simulation of cyber-physical systems. In addition, the standardization of the language by the non-profit organization Modelica Association enables Modelica models to be portable between a growing number of tools. Modelica is now used in many industries including automotive, energy and process, aerospace, and industrial equipment. Modelica is the language of choice for model-based systems engineering. The FMI standard has been added to the project portfolio of the Modelica Association. FMI provides a complementary standard that enables deployment of pre-compiled high quality models originating from different model formats to a larger number of engineers working with system design and verification.

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    Proceedings of the 11th International Modelica Conference, Versailles, France, September 21-23, 2015
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  • 259.
    Fritzson, Peter
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Pop, Adrian
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Sjölund, Martin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Asghar, Adeel
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    MetaModelica – A Symbolic-Numeric Modelica Language and Comparison to Julia2019Ingår i: Proceedings of the 13th International Modelica Conference, Regensburg, Germany, March 4–6, 2019 / [ed] Anton Haumer: OTH Regensburg, Germany, Linköping, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    The need for integrating system modeling with advanced tool capabilities is becoming increasingly pronounced. For example, a set of simulation experiments may give rise to new data that are used to systematically construct a series of new models, e.g. for further simulation and design optimization. Such combined symbolic-numeric capabilities have been pioneered by dynamically typed interpreted languages such as Lisp and Mathematica. Such capabilities are also relevant for advanced modeling and simulation applications but lacking in the standard Modelica language. Therefore, this is a topic of long-running design discussions in the Modelica Design group. One contribution in this direction is MetaModelica, that has been developed to extend Modelica with symbolic operations and advanced data structures, while preserving safe engineering practices through static type checking and a compilation-based efficient implementation. Another recent effort is Modia, implemented using the Julia macro mechanism, making it dynamically typed but also adding new capabilities. The Julia language has appeared rather recently and has expanded into a large and fast-growing ecosystem. It is dynamically typed, provides both symbolic and numeric operations, advanced data structures, and has a just-intime compilation-based efficient implementation. Despite independent developments there are surprisingly many similarities between Julia and MetaModelica. This paper presents MetaModelica and its environment as a large case study, together with a short comparison to Julia. Since Julia may be important for the future Modelica, some integration options between Modelica tools and Julia are also discussed, including a possible approach for implementing MetaModelica (and OpenModelica) in Julia.

  • 260.
    Fulla, Peter
    et al.
    Univ Oxford, England.
    Uppman, Hannes
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Zivny, Stanislav
    Univ Oxford, England.
    The Complexity of Boolean Surjective General-Valued CSPs2019Ingår i: ACM Transactions on Computation Theory, ISSN 1942-3454, E-ISSN 1942-3462, Vol. 11, nr 1, artikel-id 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Valued constraint satisfaction problems (VCSPs) are discrete optimisation problems with a (Q boolean OR{infinity})-valued objective function given as a sum of fixed-arity functions. In Boolean surjective VCSPs, variables take on labels from D = {0, 1}, and an optimal assignment is required to use both labels from D. Examples include the classical global Min-Cut problem in graphs and the Minimum Distance problem studied in coding theory. We establish a dichotomy theorem and thus give a complete complexity classification of Boolean surjective VCSPs with respect to exact solvability. Our work generalises the dichotomy for {0, infinity}-valued constraint languages (corresponding to surjective decision CSPs) obtained by Creignou and Hebrard. For the maximisation problem of Q(amp;gt;= 0)-valued surjective VCSPs, we also establish a dichotomy theorem with respect to approximability. Unlike in the case of Boolean surjective (decision) CSPs, there appears a novel tractable class of languages that is trivial in the non-surjective setting. This newly discovered tractable class has an interesting mathematical structure related to downsets and upsets. Our main contribution is identifying this class and proving that it lies on the borderline of tractability. A crucial part of our proof is a polynomial-time algorithm for enumerating all near-optimal solutions to a generalised Min-Cut problem, which might be of independent interest.

  • 261.
    Färnqvist, Tommy
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Constraint Optimization Problems and Bounded Tree-width Revisited2012Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The valued constraint satisfaction problem (VCSP) is an optimization framework originating from artificial intelligence which generalizes the classical constraint satisfaction problem (CSP). In this paper, we are interested in structural properties that can make problems from the VCSP framework, as well as other CSP variants, solvable to optimality in polynomial time. So far, the largest structural class that is known to be polynomial-time solvable to optimality is the class of bounded hypertree width instances introduced by Gottlob et al. Here, larger classes of tractable instances are singled out by using dynamic programming and structural decompositions based on a hypergraph invariant proposed by Grohe and Marx. In the second part of the paper, we take a different view on our optimization problems; instead of considering fixed arbitrary values for some structural invariant of the (hyper)graph structure of the constraints, we consider the problems parameterized by the tree-width of primal, dual, and incidence graphs, combined with several other basic parameters such as domain size and arity. Such parameterizations of plain CSPs have been studied by Samer and Szeider. Here, we extend their framework to encompass our optimization problems, by coupling it with further non-trivial machinery and new reductions. By doing so, we are able to determine numerous combinations of the considered parameters that make our optimization problems admit fixed-parameter algorithms.

  • 262.
    Färnqvist, Tommy
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Counting Homomorphisms via Hypergraph-based Structural Restrictions2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    The way in which the graph structure of the constraints influences the computational complexity of counting constraint satisfaction problems (#CSPs) is well understood for constraints of bounded arity. The situation is less clear if there is no bound on the arities. Here we initiate the systematic study of these problems and identify new classes of polynomial time solvable instances based on dynamic programming over tree decompositions, in a way generalizing well-known approaches to combinatorial optimization problems on bounded treewidth graphs, but basing the decompositions on various hypergraph width measures from the literature on plain CSPs.

  • 263.
    Färnqvist, Tommy
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Exploiting Structure in CSP-related Problems2013Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis we investigate the computational complexity and approximability of computational problems from the constraint satisfaction framework. An instance of a constraint satisfaction problem (CSP) has three components; a set V of variables, a set D of domain values, and a set of constraints C. The constraints specify a set of variables and associated local conditions on the domain values allowed for each variable, and the objective of a CSP is to assign domain values to the variables, subject to these constraints.

    The first main part of the thesis is concerned with studying restrictions on the structure induced by the constraints on the variables for different computational problems related to the CSP. In particular, we examine how to exploit various graph, and hypergraph, acyclicity measures from the literature to find classes of relational structures for which our computational problems become efficiently solvable. Among the problems studied are, such where, in addition to the constraints of a CSP, lists of allowed domain values for each variable are specified (LHom). We also study variants of the CSP where the objective is changed to: counting the number of possible assignments of domain values to the variables given the constraints of a CSP (#CSP), minimising or maximising the cost of an assignment satisfying all constraints given various different ways of assigning costs to assignments (MinHom, Max Sol, and CSP), or maximising the number of satisfied constraints (Max CSP). In several cases, our investigations uncover the largest known (or possible) classes of relational structures for which our problems are efficiently solvable. Moreover, we take a different view on our optimisation problems MinHom and VCSP; instead of considering fixed arbitrary values for some (hyper)graph acyclicity measure associated with the underlying CSP, we consider the problems parameterised by such measures in combination with other basic parameters such as domain size and maximum arity of constraints. In this way, we identify numerous combinations of the considered parameters which make these optimisation problems admit fixed-parameter algorithms.

    In the second part of the thesis, we explore the approximability properties of the (weighted) Max CSP problem for graphs. This is a problem which is known to be approximable within some constant ratio, but not believed to be approximable within an arbitrarily small constant ratio. Thus it is of interest to determine the best ratio within which the problem can be approximated, or at least give some bound on this constant. We introduce a novel method for studying approximation ratios which, in the context of Max CSP for graphs, takes the form of a new binary parameter on the space of all graphs. This parameter may, informally, be thought of as a sort of distance between two graphs; knowing the distance between two graphs, we can bound the approximation ratio of one of them, given a bound for the other.

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    Exploiting Structure in CSP-related Problems
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  • 264.
    Färnqvist, Tommy
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Heintz, Fredrik
    Linköpings universitet, Institutionen för datavetenskap, Artificiell intelligens och integrerade datorsystem. Linköpings universitet, Tekniska fakulteten.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Mannila, Linda
    Åbo Academy, Finland.
    Wang, Chunyan
    Linköpings universitet, Institutionen för datavetenskap.
    Supporting Active Learning by Introducing an Interactive Teaching Tool in a Data Structures and Algorithms Course2016Ingår i: Proceedings of the 47th ACM Technical Symposium on Computer Science Education (SIGCSE 2016), ACM Publications, 2016, s. 663-668Konferensbidrag (Refereegranskat)
    Abstract [en]

    Traditionally, theoretical foundations in data structures and algorithms (DSA) courses have been covered through lectures followed by tutorials, where students practise their understanding on pen-and-paper tasks. In this paper, we present findings from a pilot study on using the interactive e-book OpenDSA as the main material in a DSA course. The goal was to redesign an already existing course by building on active learning and continuous examination through the use of OpenDSA. In addition to presenting the study setting, we describe findings from four data sources: final exam, OpenDSA log data, pre and post questionnaires as well as an observation study. The results indicate that students performed better on the exam than during previous years. Students preferred OpenDSA over traditional textbooks and worked actively with the material, although a large proportion of them put off the work until the due date approaches.

  • 265.
    Färnqvist, Tommy
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Heintz, Fredrik
    Linköpings universitet, Institutionen för datavetenskap, Artificiell intelligens och integrerade datorsystem. Linköpings universitet, Tekniska fakulteten.
    Lambrix, Patrick
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska högskolan.
    Mannila, Linda
    Åbo Academy, Finland.
    Wang, Chunyan
    Linköpings universitet, Institutionen för datavetenskap.
    Supporting Active Learning Using an Interactive Teaching Tool in a Data Structures and Algorithms Course2015Ingår i: Proceedings of 5:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar (UtvSvIng), 2015, s. 76-79Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Traditionally, theoretical foundations in data structuresand algorithms (DSA) courses have been covered throughlectures followed by tutorials, where students practise theirunderstanding on pen-and-paper tasks. In this paper, we presentfindings from a pilot study on using the interactive e-bookOpenDSA as the main material in a DSA course. The goal was toredesign an already existing course by building on active learningand continuous examination through the use of OpenDSA. Inaddition to presenting the study setting, we describe findings fromfour data sources: final exam, OpenDSA log data, pre- and postcourse questionnaires as well as an observation study. The resultsindicate that students performed better on the exam than duringprevious years. Students preferred OpenDSA over traditionaltextbooks and worked actively with the material, although alarge proportion of them put off the work until the due dateapproaches.

  • 266.
    Gallastegi, Akaitz
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Web-based Real-Time Communication for Rescue Robots2014Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this thesis an audio and video streaming system is implemented for its use in rescue robots. WebRTC technology is used in order to stream in real time. Implemented in an architecture based on a Web server, two pages running WebRTC and a TURN1-STUN2 server, the system has been tested in terms of CPU and bandwidth utilization. Measurements show that when WebRTC is run in an Intel Core i3, less than 10% of CPU is used, whereas on smaller tablets the performance is not enough for running the application with the desired quality of service.

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    fulltext
  • 267.
    Ganeson, Anand
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Design and Implementation of a User Friendly OpenModelica - Python interface2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    How can Python users be empowered with the robust simulation, compilation and scripting abilities of a non-proprietary object-oriented, equation based modeling language such as Modelica? The immediate objective of this thesis work is to develop an application programming interface for the OpenModelica modeling and simulation environment that would bridge the gap between the two agile programming languages Python and Modelica.

    The Python interface to OpenModelica OMPython, is both a tool and a functional library that allows Python users to realize the full capabilities of Open- Modelica’s scripting and simulation environment requiring minimal setup actions. OMPython is designed to combine both simulation and model building. Thus domain experts (people writing the models) and computational engineers (people writing the solver code) can work on one unified tool that is industrially viable for optimization of Modelica models, while offering a flexible platform for algorithm development and research.

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    fulltext
  • 268.
    Ganjei, Zeinab
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Eles, Petru Ion
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Safety Verification of Phaser Programs2017Ingår i: PROCEEDINGS OF THE 17TH CONFERENCE ON FORMAL METHODS IN COMPUTER AIDED DESIGN (FMCAD 2017), IEEE , 2017, s. 68-75Konferensbidrag (Refereegranskat)
    Abstract [en]

    We address the problem of statically checking control state reachability (as in possibility of assertion violations, race conditions or runtime errors) and plain reachability (as in deadlock-freedom) of phaser programs. Phasers are a modern non-trivial synchronization construct that supports dynamic parallelism with runtime registration and deregistration of spawned tasks. They allow for collective and point-to-point synchronizations. For instance, phasers can enforce barriers or producer-consumer synchronization schemes among all or subsets of the running tasks. Implementations are found in modern languages such as Habanero Java. Phasers essentially associate phases to individual tasks and use their runtime values to restrict possible concurrent executions. Unbounded phases may result in infinite transition systems even in the case of programs only creating finite numbers of tasks and phasers. We introduce an exact gap-order based procedure that always terminates when checking control reachability for programs generating bounded numbers of coexisting tasks and phasers. We also show verifying plain reachability is undecidable even for programs generating few tasks and phasers. We then explain how to turn our procedure into a sound analysis for checking plain reachability (including deadlock freedom). We report on preliminary experiments with our open source tool.

  • 269.
    Ganjei, Zeinab
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Abstracting and Counting Synchronizing Processes2014Rapport (Övrigt vetenskapligt)
    Abstract [en]

    We address the problem of automatically establishing synchronization dependent correctness (e.g. due to using barriers or ensuring absence of deadlocks) of programs generating an arbitrary number of concurrent processes and manipulating variables ranging over an infinite domain. Automatically checking such properties for these programs is beyond the capabilities of current verification techniques. For this purpose, we describe an original logic that mixes two sorts of variables: those shared and manipulated by the concurrent processes, and ghost variables refering to the number of processes satisfying predicates on shared and local program variables. We then combine existing works on counter, predicate, and constrained monotonic abstraction and nest two cooperating counter example based refinement loops for establishing correctness (safety expressed as non reachability of configurations satisfying formulas in our logic). We have implemented a tool (Pacman, for predicated constrained monotonic abstraction) and used it to perform parameterized verification for several programs whose correctness crucially depends on precisely capturing the number of synchronizing processes. 

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    fulltext
  • 270.
    Ganjei, Zeinab
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Counting dynamically synchronizing processes2016Ingår i: International Journal on Software Tools for Technology Transfer (STTT), ISSN 1433-2779, E-ISSN 1433-2787, Vol. 18, nr 5, s. 517-534Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We address the problem of automatically establishing correctness for programs generating an arbitrary number of concurrent processes and manipulating variables ranging over an infinite domain. The programs we consider can make use of the shared variables to count and synchronize the spawned processes. This allows them to implement intricate synchronization mechanisms, such as barriers. Automatically verifying correctness, and deadlock freedom, of such programs is beyond the capabilities of current techniques. For this purpose, we make use of counting predicates that mix counters referring to the number of processes satisfying certain properties and variables directly manipulated by the concurrent processes. We then combine existing works on counter, predicate, and constrained monotonic abstraction and build a nested counter example based refinement scheme for establishing correctness (expressed as non-reachability of configurations satisfying counting predicates formulas). We have implemented a tool (Pacman, for predicated constrained monotonic abstraction) and used it to perform parameterized verification on several programs whose correctness crucially depends on precisely capturing the number of processes synchronizing using shared variables.

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    fulltext
  • 271.
    Ganjei, Zeinab
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Lazy Constrained Monotonic Abstraction2016Ingår i: Verification, Model Checking, and Abstract Interpretation: 17th International Conference, VMCAI 2016, St. Petersburg, FL, USA, January 17-19, 2016. Proceedings / [ed] Barbara Jobstmann; K. Rustan M. Leino, Springer Berlin/Heidelberg, 2016, Vol. 9583, s. 147-165Konferensbidrag (Refereegranskat)
    Abstract [en]

    We introduce Lazy Constrained Monotonic Abstraction (lazy CMA for short) for lazily and soundly exploring well structured abstractions of infinite state non-monotonic systems. CMA makes use of infinite state and well structured abstractions by forcing monotonicity wrt. refinable orderings. The new orderings can be refined based on obtained false positives in a CEGAR like fashion. This allows for the verification of systems that are not monotonic and are hence inherently beyond the reach of classical analysis based on the theory of well structured systems. In this paper, we consistently improve on the existing approach by localizing refinements and by avoiding to trash the explored state space each time a refinement step is required for the ordering. To this end, we adapt ideas from classical lazy predicate abstraction and explain how we address the fact that the number of control points (i.e., minimal elements to be visited) is a priori unbounded. This is unlike the case of plain lazy abstraction which relies on the fact that the number of control locations is finite. We propose several heuristics and report on our experiments using our open source prototype. We consider both backward and forward explorations on non-monotonic systems automatically derived from concurrent programs. Intuitively, the approach could be regarded as using refinable upward closure operators as localized widening operators for an a priori arbitrary number of control points.

  • 272.
    Ganjei, Zeinab
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Henrio, Ludovic
    Univ Lyon, EnsL, UCBL, CNRS, Inria, LIPLyon Cedex 07France.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    On Reachability in Parameterized Phaser Programs2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    We address the problem of statically checking safety properties (such as assertions or deadlocks) for parameterized phaser programs. Phasers embody a non-trivial and modern synchronization construct used to orchestrate executions of parallel tasks. This generic construct supports dynamic parallelism with runtime registrations and deregistrations of spawned tasks. It generalizes many synchronization patterns such as collective and point-to-point schemes. For instance, phasers can enforce barriers or producer-consumer synchronization patterns among all or subsets of the running tasks. We consider in this work programs that may generate arbitrarily many tasks and phasers. We propose an exact procedure that is guaranteed to terminate even in the presence of unbounded phases and arbitrarily many spawned tasks. In addition, we prove undecidability results for several problems on which our procedure cannot be guaranteed to terminate.

  • 273.
    Ganjei, Zeinab
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Ion Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Peng, Zebo
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Abstracting and Counting Synchronizing Processes2015Ingår i: Verification, Model Checking, and Abstract Interpretation: 16th International Conference on Verification, Model Checking, and Abstract Interpretation (VMCAI 2015), Mumbai, India, Jan. 12-14, 2015., Springer, 2015, s. 227-244Konferensbidrag (Refereegranskat)
    Abstract [en]

    We address the problem of automatically establishing synchronization dependent correctness (e.g. due to using barriers or ensuring absence of deadlocks) of programs generating an arbitrary number of concurrent processes and manipulating variables ranging over an infinite domain. Automatically checking such properties for these programs is beyond the capabilities of current verification techniques. For this purpose, we describe an original logic that mixes two sorts of variables: those shared and manipulated by the concurrent processes, and ghost variables referring to the number of processes satisfying predicates on shared and local program variables. We then combine existing works on counter, predicate, and constrained monotonic abstraction and nest two cooperating counter example based refinement loops for establishing correctness (safety expressed as non reachability of configurations satisfying formulas in our logic). We have implemented a tool (Pacman, for predicated constrained monotonic abstraction) and used it to perform parameterized verification for several programs whose correctness crucially depends on precisely capturing the number of synchronizing processes.

  • 274.
    Ganty, Pierre
    et al.
    IMDEA Software Institute, Spain.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Ordered Counter-Abstraction Refinable Subword Relations for Parameterized Verification2014Ingår i: LANGUAGE AND AUTOMATA THEORY AND APPLICATIONS (LATA 2014), Springer Berlin/Heidelberg, 2014, Vol. 8370, s. 396-408Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present an original refinable subword based symbolic representation for the verification of linearly ordered parameterized systems. Such a system consists of arbitrary many finite processes placed in an array. Processes communicate using global transitions constrained by their relative positions (i.e., priorities). The model can include binary communication, broadcast, shared variables or dynamic creation and deletion of processes. Configurations are finite words of arbitrary lengths. The successful monotonic abstraction approach uses the subword relation to define upward closed sets as symbolic representations for such systems. Natural and automatic refinements remained missing for such symbolic representations. For instance, subword based relations are simply too coarse for automatic forward verification of systems involving priorities. We remedy to this situation and introduce a symbolic representation based on an original combination of counter abstraction with subword based relations. This allows us to define an infinite family of relaxation operators that guarantee termination by a new well quasi ordering argument. The proposed automatic analysis is at least as precise and efficient as monotonic abstraction when performed backwards. It can also be successfully used in forward, something monotonic abstraction is incapable of. We implemented a prototype to illustrate the approach.

  • 275.
    Garro, Alfredo
    et al.
    Department of Informatics, Modeling, Electronics and Systems Engineering (DIMES), University of Calabria, Italy.
    Tundis, Andrea
    Department of Informatics, Modeling, Electronics and Systems Engineering (DIMES), University of Calabria, Italy.
    Bouskela, Daniel
    R&D Division, Electricité de France (EDF), France.
    Jardin, Audrey
    R&D Division, Electricité de France (EDF), France.
    Nguyen, Thuy
    R&D Division, Electricité de France (EDF), France.
    Otter, Martin
    Institute of System Dynamics and Control, DLR German Aerospace Center, Germany.
    Buffoni, Lena
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Sjölund, Martin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Schamai, Wladimir
    Airbus Group Innovations, Hamburg, Germany.
    Olsson, Hans
    Dassault Systèmes AB, Sweden.
    On formal cyber physical system properties modeling: a new temporal logic language and a Modelica-based solution2016Ingår i: 2016 IEEE International Symposium on Systems Engineering (ISSE), IEEE , 2016, s. 112-119Konferensbidrag (Refereegranskat)
    Abstract [en]

    Modeling and Simulation methods, tools and techniques aim at supporting the different phases of the lifecycle of modern systems, going from requirements analysis to system design and operation. However, their effective application requires investigating several aspects such as the formal modeling of system requirements and the binding and automated composition between heterogeneous models (e.g. requirements models, architectural models, behavioral models). In this context, the paper presents a new formal requirement modeling language based on temporal logic, called FORM-L, and a software library, based on the Modelica language, that implements the constructs provided by FORM-L so as to enable the visual modeling of system properties as well as their verification through simulation. The effectiveness of the proposal is shown on a real case study concerning an Intermediate Cooling System.

  • 276.
    Gatla, Goutham
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Validation of ModelicaML models2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In the world of modeling, Model Validation plays a crucial role. A model editor is not said to becomplete without Validation. ModelicaML is a Modeling Language extended from a subset of UMLand SysML, developed under OpenModelica Project. It is defined to provide time-discrete andtime-continuous models. Papyrus Model Editor is extended to support for ModelicaML usingModelicaML Eclipse plug-in. This plug-in comes with Modelica Code Generator.Previously, ModelicaML plug-in had a prototype of validation which provided only Batch-modevalidation. The validation is used to be done by the Modelica compiler after the code generation phase.Each time the user tried to validate the model; first Modelica code is generated and then validated. Thistype of validation misses certain validation rules to validate due to the conversion from theModelicaML model to Modelica code.The goal of this thesis is to implement Model Validation done at model editor level with both Batch andLive mode validation. This can be done by developing an Eclipse plug-in which does the ModelValidation. This plug-in uses the EMF Validation framework for implementing the constraints andvalidation on ModelicaML models.

    Ladda ner fulltext (pdf)
    Validation_of_ModelicaML_models
  • 277.
    Gavrilut, Voica
    et al.
    Tech Univ Denmark, Denmark.
    Zarrin, Bahram
    Tech Univ Denmark, Denmark.
    Pop, Paul
    Tech Univ Denmark, Denmark.
    Samii, Soheil
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten. Gen Motors RandD, MI USA.
    Fault-Tolerant Topology and Routing Synthesis for IEEE Time-Sensitive Networking2017Ingår i: PROCEEDINGS OF THE 25TH INTERNATIONAL CONFERENCE ON REAL-TIME NETWORKS AND SYSTEMS (RTNS 2017), ASSOC COMPUTING MACHINERY , 2017, s. 267-276Konferensbidrag (Refereegranskat)
    Abstract [en]

    Time-Sensitive Networking (TSN) is a set of IEEE standards that extend Ethernet for safety-critical and real-time applications. TSN is envisioned to be widely used in several applications areas, from industrial automation to in-vehicle networking. A TSN network is composed of end systems interconnected by physical links and bridges (switches). The data in TSN is exchanged via streams. We address safety-critical real-time systems, and we consider that the streams use the Urgency-Based Scheduler (UBS) traffic-type, suitable for hard real-time traffic. We are interested in determining a fault-tolerant network topology, consisting of redundant physical links and bridges, the routing of each stream in the applications, such that the architecture cost is minimized, the applications are fault-tolerant (i.e., the critical streams have redundant disjoint routes), and the timing constraints of the applications are satisfied. We propose three approaches to solve this optimization problem: (1) a heuristic solution, (2) a Greedy Randomized Adaptive Search Procedure (GRASP) metaheuristic, and (3) a Constraint Programming based model. The approaches are evaluated on several test cases, including a test case from General Motors Company.

  • 278.
    Gebremedhin, Mahder
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Automatic and Explicit Parallelization Approaches for Equation Based Mathematical Modeling and Simulation2018Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [sv]

    Övergången från datorer med en processor till datorer med flera processorkärnor ställer krav på att implementera beräkningar på ett sådant sätt att dessa multipla beräkningsenheter kan användas effektivt. Skrivande av effektiva parallella algoritmer är mycket arbetskrävande och en stor källa till fel om inte programmeringsspråk och tillhörande kompilatorer kan förbättras till att erbjuda bättre stödmekanismer. Datorstödd matematisk modellering och simulering är ett av de mest beräkningsintensiva områdena inom datavetenskap. Även simuleringar av förenklade modeller av fysikaliska system kan vara mycket beräkningstungt med användning av standardprocessorer. Att kunna dra nytta av den beräkningskraft som erbjuds av moderna flerkärniga arkitekturer är mycket viktigt inom detta tillämpningsområde. Denna avhandling syftar till att ge bidrag till hur beräkningskraften hos moderna flerkärniga processor kan utnyttja för att öka prestanda för simuleringar, speciellt för modeller uttryckta i det ekvationsbaserade högnivåmodelleringsspråket Modelica, kompilerade och simulerade med användning av OpenModelica’s modellkompilator och beräkningsmiljö.

    Denna avhandling presenterar två metoder för att simulera matematiska modeller på ett sådant sätt att beräkningskraften hos moderna flerkärniga datorer kan utnyttjas: automatisk respektive explicit parallellisering. Den automatiska metoden utför automatiskt processen att extrahera och använda potentiell parallelism i ekvationssystem från den matematiska modellen utan att programmeraren eller modelleraren behöver göra någon extra ansträngning. I denna avhandling presenteras nya och förbättrade metoder tillsammans med förbättringar i OpenModelicakompilatorn samt ett nytt programbibliotek som stödjer effektiv representation, gruppering, planering, prestandamätning och exekvering av komplexa system av ekvationer och beräkningar, där dessa ofta är beroende av varandra. Den explicita parallelliseringsmetoden utnyttjar parallellism som uttrycks explicit med hjälp av programmeraren eller modelleraren. Nya språkkonstruktioner i Modelicaspråket har introduceras för att göra det möjligt för modellerare att på ett bekvämt sätt uttrycka parallelliserad algoritmer som kan utnyttja beräkningskraften som erbjuds av moderna flerkärniga standardprocessorer och grafikprocessorer. OpenModelicakompilatorn har utökats för att kunna hantera och utnyttja informationen från dessa nya språkkonstruktioner samt att generera parallell kod med ökad beräkningsprestanda. Den genererade koden är portabel till ett antal parallella datorarkitekturer genom OpenCL standarden. Dessutom presenteras prestandamätningar av testmodeller med användning av båda metoderna.

    Övergången från datorer med en processor till datorer med flera processorkärnor ställer krav på att implementera beräkningar på ett sådant sätt att dessa multipla beräkningsenheter kan användas effektivt. Skrivande av effektiva parallella algoritmer är mycket arbetskrävande och en stor källa till fel om inte programmeringsspråk och tillhörande kompilatorer kan förbättras till att erbjuda bättre stödmekanismer. Datorstödd matematisk modellering och simulering är ett av de mest beräkningsintensiva områdena inom datavetenskap. Även simuleringar av förenklade modeller av fysikaliska system kan vara mycket beräkningstungt med användning av standardprocessorer. Att kunna dra nytta av den beräkningskraft som erbjuds av moderna flerkärniga arkitekturer är mycket viktigt inom detta tillämpningsområde. Denna avhandling syftar till att ge bidrag till hur beräkningskraften hos moderna flerkärniga processor kan utnyttja för att öka prestanda för simuleringar, speciellt för modeller uttryckta i det ekvationsbaserade högnivåmodelleringsspråket Modelica, kompilerade och simulerade med användning av OpenModelica’s modellkompilator och beräkningsmiljö.

    Denna avhandling presenterar två metoder för att simulera matematiska modeller på ett sådant sätt att beräkningskraften hos moderna flerkärniga datorer kan utnyttjas: automatisk respektive explicit parallellisering. Den automatiska metoden utför automatiskt processen att extrahera och använda potentiell parallelism i ekvationssystem från den matematiska modellen utan att programmeraren eller modelleraren behöver göra någon extra ansträngning. I denna avhandling presenteras nya och förbättrade metoder tillsammans med förbättringar i OpenModelicakompilatorn samt ett nytt programbibliotek som stödjer effektiv representation, gruppering, planering, prestandamätning och exekvering av komplexa system av ekvationer och beräkningar, där dessa ofta är beroende av varandra. Den explicita parallelliseringsmetoden utnyttjar parallellism som uttrycks explicit med hjälp av programmeraren eller modelleraren. Nya språkkonstruktioner i Modelicaspråket har introduceras för att göra det möjligt för modellerare att på ett bekvämt sätt uttrycka parallelliserad algoritmer som kan utnyttja beräkningskraften som erbjuds av moderna flerkärniga standardprocessorer och grafikprocessorer. OpenModelicakompilatorn har utökats för att kunna hantera och utnyttja informationen från dessa nya språkkonstruktioner samt att generera parallell kod med ökad beräkningsprestanda. Den genererade koden är portabel till ett antal parallella datorarkitekturer genom OpenCL standarden. Dessutom presenteras prestandamätningar av testmodeller med användning av båda metoderna.

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    Automatic and Explicit Parallelization Approaches for Equation Based Mathematical Modeling and Simulation
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  • 279.
    Gebremedhin, Mahder
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Automatic and Explicit Parallelization Approaches for Mathematical Simulation Models2015Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The move from single core and processor systems to multi-core and many-processors systemscomes with the requirement of implementing computations in a way that can utilizethese multiple units eciently. This task of writing ecient multi-threaded algorithmswill not be possible with out improving programming languages and compilers to providethe mechanisms to do so. Computer aided mathematical modeling and simulationis one of the most computationally intensive areas of computer science. Even simpli-ed models of physical systems can impose a considerable amount of computational loadon the processors at hand. Being able to take advantage of the potential computationpower provided by multi-core systems is vital in this area of application. This thesis triesto address how we can take advantage of the potential computation power provided bythese modern processors to improve the performance of simulations. The work presentsimprovements for the Modelica modeling language and the OpenModelica compiler.

    Two approaches of utilizing the computational power provided by modern multi-corearchitectures are presented in this thesis: Automatic and Explicit parallelization. Therst approach presents the process of extracting and utilizing potential parallelism fromequation systems in an automatic way with out any need for extra eort from the modelers/programmers side. The thesis explains improvements made to the OpenModelicacompiler and presents the accompanying task systems library for ecient representation,clustering, scheduling proling and executing complex equation/task systems with heavydependencies. The Explicit parallelization approach explains the process of utilizing parallelismwith the help of the modeler or programmer. New programming constructs havebeen introduced to the Modelica language in order to enable modelers write parallelizedcode. the OpenModelica compiler has been improved accordingly to recognize and utilizethe information from this new algorithmic constructs and generate parallel code toimprove the performance of computations.

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    omslag
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  • 280.
    Gebremedhin, Mahder
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Automatic Task Based Analysis and Parallelization in the Context of Equation Based Languages2014Ingår i: EOOLT '14 Proceedings of the 6th International Workshop on Equation-Based Object-Oriented Modeling Languages and Tools, New York: ACM , 2014, s. 49-52Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an automatic parallelization approach for handling complex task systems with heavy dependencies, including methods of analyzing dependencies, representing them in a convenient way, and processing the resulting task graph representation. We present a library-based task system representation, clustering, profiling, and scheduling approach to simplify the otherwise tedious process of parallelizing complex task systems. We have implemented a flexible and robust task system handling library to manipulate and parallelize these complex task systems on shared memory multi-core and multi-processor systems. The implementation has been developed as part of the OpenModelica simulation environment. We demonstrate methods of extracting and utilizing parallelism in the context of mathematical modeling languages.

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  • 281.
    Gerling, Jonas
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Implementing Object and Feature Detection Without Compromising the Performance2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis will cover how some computationally heavy algorithms used in digital image processing and computer vision are implemented with WebGL and computed on the graphics processing unit by utilizing GLSL-shaders. This thesis is based on an already implemented motion detection plug-in used in web based games. This plug-in is enhanced with new features and some already implemented algorithms are improved. The motion detection is based on image subtraction and uses the delta image from previous frames to determine motion.

    The plug-in is used in web based games so the performance is of utmost importance since bad performance leads to frustration and less immersion for the players

    Techniques brought up are edge detection, Gaussian filter, features from accelerated segment test(FAST) and Harris corner detection. These techniques will be implemented by utilizing the parallel structure of the GPU. Both Harris corner detection and features from accelerated segment test can be run in real time but the result of the Harris corner detection is the better of the two. The thesis will also cover different color spaces, how they are implemented and why they were implemented

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  • 282.
    Ghani Zadegan, Farrokh
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Ingelsson, Urban
    Semcon AB.
    Carlsson, Gunnar
    Ericsson AB.
    Larsson, Erik
    Lund University, Sweden .
    Access Time Analysis for IEEE P16872012Ingår i: I.E.E.E. transactions on computers (Print), ISSN 0018-9340, E-ISSN 1557-9956, Vol. 61, nr 10, s. 1459-1472Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The IEEE P1687 (IJTAG) standard proposal aims at providing a standardized interface between the IEEE Standard 1149.1 test access port (TAP) and on-chip embedded test, debug and monitoring logic (instruments), such as scan chains and temperature sensors. A key feature in P1687 is to include Segment Insertion Bits (SIBs) in the scan path to allow flexibility both in designing the instrument access network and in scheduling the access to instruments. This paper presents algorithms to compute the overall access time (OAT) for a given P1687 network. The algorithms are based on analysis for flat and hierarchical network architectures, considering two access schedules, i.e., concurrent schedule and sequential schedule. In the analysis, two types of overhead are identified, i.e., network configuration data overhead and JTAG protocol overhead. The algorithms are implemented and employed in a parametric analysis and in experiments on realistic industrial designs.

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  • 283.
    Gillsjö, Lukas
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Using OpenCL to Implement Median Filtering and RSA Algorithms: Two GPGPU Application Case Studies2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Graphics Processing Units (GPU) and their development tools have advanced recently, and industry has become more interested in using them. Among several development frameworks for GPU(s), OpenCL provides a programming environment to write portable code that can run in parallel. This report describes two case studies of algorithm implementations in OpenCL. The first algorithm is Median Filtering which is a widely used image processing algorithm. The other algorithm is RSA which is a popular algorithm used in encryption. The CPU and GPU implementations of these algorithms are compared in method and speed. The GPU implementations are also evaluated by efficiency, stability, scalability and portability. We find that the GPU implementations perform better overall with some exceptions. We see that a pure GPU solution is not always the best and that a hybrid solution with both CPU and GPU may be to prefer in some cases.

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  • 284.
    Girma, Robi
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Evaluation of container virtualization systems supporting Open Container Initiative images2018Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Abstract

    In the Virtualization industry, container virtualization has increased in popularity with the emergence of container engines in 2013. Container engines create, remove and manage containers. They do so by utilizing container images from which containers are created. Images work as templates, are reusable and can be uploaded for others to download. Big contributors in the field of container virtualization grouped up and founded the Open Container Initiative. The project established an industry standard for the architecture of container images and how they should be run.

     

    The IT consultant company Zenon has requested a thesis to be done in the field of container virtualization as they are thinking of starting to work with one but want to learn more about modern solutions. Due to the lack of back-to-back comparisons of modern solutions supporting the standard set by the Open Container Initiative, this thesis makes an evaluation of available systems in industry standard terms of performance. The company is also interested in fields; isolation, image management and time to build an image of a Zenon application and deploy a container from it.

     

    The evaluation in this thesis was made on container engines Docker and rkt. Results showed that Docker performed better in all benchmarks. Rkt starts a container in less time than Docker but takes longer to build the specified image. Docker has much more capabilities in terms of image management with the ability to create images from scratch and to run on multiple operating systems, while rkt has limited ability for creating images, requires more configurations and is exclusive available for Linux. Both container engines offer varied isolation, where Docker has 2 security profiles and rkt lets the user implement custom isolation profiles with several provided options available.

  • 285.
    Glasser, Christian
    et al.
    University of Wurzburg, Germany.
    Jonsson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Martin, Barnaby
    Middlesex University, England.
    Circuit Satisfiability and Constraint Satisfaction Around Skolem Arithmetic2016Ingår i: Pursuit of the Universal, SPRINGER INT PUBLISHING AG , 2016, Vol. 9709, s. 323-332Konferensbidrag (Refereegranskat)
    Abstract [en]

    We study interactions between Skolem Arithmetic and certain classes of Circuit Satisfiability and Constraint Satisfaction Problems (CSPs). We revisit results of Gla beta er et al. [16] in the context of CSPs and settle the major open question from that paper, finding a certain satisfiability problem on circuits-involving complement, intersection, union and multiplication-to be decidable. This we prove using the decidability of Skolem Arithmetic. Then we solve a second question left open in [16] by proving a tight upper bound for the similar circuit satisfiability problem involving just intersection, union and multiplication. We continue by studying first-order expansions of Skolem Arithmetic without constants, (N; x), as CSPs. We find already here a rich landscape of problems with non-trivial instances that are in P as well as those that are NP-complete.

  • 286.
    Glasser, Christian
    et al.
    Julius Maximilian University, Germany.
    Jonsson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Martin, Barnaby
    University of Durham, England.
    Circuit satisfiability and constraint satisfaction around Skolem Arithmetic2017Ingår i: Theoretical Computer Science, ISSN 0304-3975, E-ISSN 1879-2294, Vol. 703, s. 18-36Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study interactions between Skolem Arithmetic and certain classes of Circuit Satisfiability and Constraint Satisfaction Problems (CSPs). We revisit results of Glasser et al. [1] in the context of CSPs and settle the major open question from that paper, finding a certain satisfiability problem on circuits-involving complement, intersection, union and multiplication-to be decidable. This we prove using the decidability of Skolem Arithmetic. Then we solve a second question left open in [1] by proving a tight upper bound for the similar circuit satisfiability problem involving just intersection, union and multiplication. We continue by studying first-order expansions of Skolem Arithmetic without constants, (N; x), as CSPs. We find already here a rich landscape of problems with non-trivial instances that are in P as well as those that are NP-complete. (C) 2017 Elsevier B.V. All rights reserved.

  • 287.
    Gomes de Oliveira Neto, Francisco
    et al.
    Chalmers/University of Gothenburg, Sweden.
    Ahmad, Azeem
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Leifler, Ola
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Sandahl, Kristian
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Enoiu, Eduard
    Mälardalen University, Sweden.
    Improving continuous integration with similarity-based test case selection2018Ingår i: Proceedings of the 13th International Workshop on Automation of Software Test, New York: ACM Digital Library, 2018, s. 39-45Konferensbidrag (Refereegranskat)
    Abstract [en]

    Automated testing is an essential component of Continuous Integration (CI) and Delivery (CD), such as scheduling automated test sessions on overnight builds. That allows stakeholders to execute entire test suites and achieve exhaustive test coverage, since running all tests is often infeasible during work hours, i.e., in parallel to development activities. On the other hand, developers also need test feedback from CI servers when pushing changes, even if not all test cases are executed. In this paper we evaluate similarity-based test case selection (SBTCS) on integration-level tests executed on continuous integration pipelines of two companies. We select test cases that maximise diversity of test coverage and reduce feedback time to developers. Our results confirm existing evidence that SBTCS is a strong candidate for test optimisation, by reducing feedback time (up to 92% faster in our case studies) while achieving full test coverage using only information from test artefacts themselves.

  • 288.
    Gorm Larsen, Peter
    et al.
    Aarhus University, Denmark.
    Fitzgerald, John
    Newcastle University, England.
    Woodcock, Jim
    University of York, England.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Brauer, Joerg
    Verified Syst Int, Germany.
    Kleijn, Christian
    Controllab Prod, Netherlands.
    Lecomte, Thierry
    Clearsy SAS, France.
    Pfeil, Markus
    TWT Science and Innovat, Germany.
    Green, Ole
    Agro Intelligence, Denmark.
    Basagiannis, Stylianos
    United Technology Research Centre, Ireland.
    Sadovykh, Andrey
    Softeam, France.
    Integrated Tool Chain for Model-based Design of Cyber-Physical Systems: The INTO-CPS Project2016Ingår i: 2016 2ND INTERNATIONAL WORKSHOP ON MODELLING, ANALYSIS, AND CONTROL OF COMPLEX CPS (CPS DATA), IEEE , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    We describe INTO-CPS, a project that aims to realise the goal of integrated tool chains for the collaborative and multidisciplinary engineering of dependable Cyber-Physical Systems (CPSs). Challenges facing model-based CPS engineering are described, focussing on the semantic diversity of models, management of the large space of models and artefacts produced in CPS engineering, and the need to evaluate effectiveness in industrial settings. We outline the approach taken to each of these issues, particularly on the use of semantically integrated multi-models, links to architectural modelling, code generation and testing, and evaluation via industry-led studies. We describe progress on the development of a prototype tool chain from baseline tools, and discuss ongoing challenges and open research questions in this area.

  • 289.
    Grahn, Ivar
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    The Vuforia SDK and Unity3D Game Engine: Evaluating Performance on Android Devices2017Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This paper evaluates major features of PTC’s augmented reality SDK Vuforia, available for Android, iOS and the Unity3D game engine. The performance of these features are evaluated in terms of frame rate and power consumption and the testing prototypes are developed using Unity3D. Augmented reality is a rapidly growing medium and the Vuforia SDK is very popular with over 325 000 registered developers and thousands of published applications. Despite being used to such extents, there are surprisingly few works evaluating different aspects of its performance. This paper provides an introduction to augmented reality and describes the technology used by the Vuforia SDK to deliver said features. This paper shows that Vuforia is capable of maintaining sufficient performance with interactive frame rates over 20 Hz in most cases. The power consumption of these features reduces the battery lifetime to acceptable levels, suitable for hand-held devices. In some cases, however, the performance in terms of frame rate reaches levels lower than recommended. These cases should be considered by developers looking to use Vuforia.

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  • 290.
    Granli, Petter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Semantic segmentation of seabed sonar imagery using deep learning2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    For investigating the large parts of the ocean which have yet to be mapped, there is a need for autonomous underwater vehicles. Current state-of-the-art underwater positioning often relies on external data from other vessels or beacons. Processing seabed image data could potentially improve autonomy for underwater vehicles.

    In this thesis, image data from a synthetic aperture sonar (SAS) was manually segmented into two classes: sand and gravel. Two different convolutional neural networks (CNN) were trained using different loss functions, and the results were examined. The best performing network, U-Net trained with the IoU loss function, achieved dice coefficient and IoU scores of 0.645 and 0.476, respectively. It was concluded that CNNs are a viable approach for segmenting SAS image data, but there is much room for improvement.

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  • 291.
    Grape, Victor
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Comparing Costs of Browser Automation Test Tools with Manual Testing2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Testing is a necessary component of software development, but it is also an expensive one, especially if performed manually. One way to mitigate the cost of testing is to implement test automation, where the test cases are run automatically. For any organisation looking to implement test automation, the most interesting cost is time. Automation takes time to implement and one of the most obvious benefits of automation is that the automated test execution time is lower than that of manual execution. This thesis contains a literature study covering testing methodology, especially in regards to the domain of web application testing. The literature covered also included three economic models that may be used to calculate the costs of automation compared to manual testing. The models can be used to calculate the time it would take, or the number of necessary executions, for the total cost of test automation to be lower than of that of manual testing. The thesis is based on a case study of test automation for the StoredSafe platform, a web application. Three sets of test automation frameworks were used to implement three different test suits and the test implementation times were collected. The data collected were then used to calculate the time it would take, using the three economic models, for the cost of automated test cases to become equal to that of with manual testing. The data showed that the estimated time to reach breakeven for the three frameworks varied between 2½ and at worst 10 years, with an average of 3½ years. The models and data presented in this thesis may be used in order to estimate the cost of test automation in comparison to manual testing over longer periods of time, but care must be taken in order to ensure that the data used is correct in regards to one’s own organisation or else the estimate may be faulty.

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    Comparing Costs of Browser Automation Test Tools with Manual Testing
  • 292.
    Green Olander, Jens
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Optimizing Communication Energy Efficiency for a Multimedia Application2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Mobile devices have evolved rapidly in recent years and increased usage and performance are pushing contemporary battery technology to its limits. The constrained battery resources mean that the importance of energy-efficient application design is growing and in this regard wireless network accesses are a major contributor to a mobile device's overall energy consumption. Additionally, the energy consumption characteristics of modern cellular technologies make small volumes of poorly scheduled traffic account for a substantial share of a device's total energy consumption. However, quantifying the communication energy footprint is cumbersome, making it difficult for developers to profile applications from an energy consumption perspective and optimize traffic patterns.

    This thesis examines the traffic patterns of the Android client of the popular multimedia streaming service Spotify with the intention to reduce its energy footprint, in terms of 3G energy consumption. The application's automated test environment is extended to capture network traffic, which is used to estimate energy consumption. Automated system tests are designed and executed on a physical Android device connected to a 3G network, shedding light on the traffic patterns of different application features.

    All traffic between the Spotify client application and the backend servers is encrypted. To extract information about the traffic, the application code is instrumented to output supplementary information to the Android system log. The system log is then used as a source of information to attribute data traffic to different application modules and specific lines of code.

    Two simple traffic shaping techniques, traffic aggregation and piggybacking, are implemented in the application to provide more energy-efficient traffic patterns. As a result, 3G energy consumption during normal music playback is reduced by 22-54%, and a more contrived scenario achieves a 60% reduction. The reductions are attained by rescheduling a small class of messages, most notably data tracking application usage. These messages were found to account for a small fraction of total traffic volume, but a large portion of the application's overall 3G energy consumption.

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    Optimizing Communication Energy Efficiency for a Multimedia Application
  • 293.
    Grimsdal, Gunnar
    et al.
    Omegapoint, Stockholm, Sweden.
    Lundgren, Patrik
    Westermo Network Technologies, Stora Sundby, Sweden.
    Vestlund, Christian
    Sectra AB, Linköping, Sweden.
    Boeira, Felipe
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Asplund, Mikael
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Can Microkernels Mitigate Microarchitectural Attacks?2019Ingår i: Secure IT Systems: Nordsec 2019 / [ed] Aslan Askarov, René Rydhof Hansen, Willard Rafnsson, Cham: Springer, 2019, s. 238-253Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Microarchitectural attacks such as Meltdown and Spectre have attracted much attention recently. In this paper we study how effective these attacks are on the Genode microkernel framework using three different kernels, Okl4, Nova, and Linux. We try to answer the question whether the strict process separation provided by Genode combined with security-oriented kernels such as Okl4 and Nova can mitigate microarchitectural attacks. We evaluate the attack effectiveness by measuring the throughput of data transfer that violates the security properties of the system. Our results show that the underlying side-channel attack Flush+Reload used in both Meltdown and Spectre, is effective on all investigated platforms. We were also able to achieve high throughput using the Spectre attack, but we were not able to show any effective Meltdown attack on Okl4 or Nova.

  • 294.
    Grundström, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    A Security Analysis of a Credit Card Payment System for Bitcoin Transactions2018Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Cryptocurrencies has become a very hot topic recently, with Bitcoin being the most

    popular. The increase in interest has led to an incentive to create payment systems for the

    currency that makes it easier to use for day-to-day shopping. A lot of companies are inves-

    tigating possible solutions for credit cards that are used for cryptocurrencies. This thesis

    aims to present and perform a security analysis on an already created concept of a credit

    card payment system for Bitcoin. The security analysis is done in a systematical approach

    where the modules were analyzed with predetermined restrictions and assumptions. The

    restricitons and assumptions are then removed one-by-one to find potential threats in the

    system. The outcome of the analysis is then evaluated in an attempt to find possible im-

    plementation methods that would mitigate or prevent the discovered threats. The possible

    implementations are also evaluated in terms of how they would affect the system.

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  • 295.
    Gustafsson, Anders
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Use of head mounted virtual reality displays in flight training simulation2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The purpose of this thesis was to evaluate currently commercially available head mounted virtual reality displays for potential use in pilot training simulators. For this purpose acommercial simulator was modified to display the virtual environment in an Oculus RiftDK2 headset. A typical monitor based setup was used to provide a set of hardware requirements which the VR implementation had to meet or exceed to be considered potentially usable for pilot training simulators. User tests were then performed with a group of users representative of those normally using pilot training simulators, including both pilots and engineers working with simulator development. The main focus of the user tests was to evaluate some potential weaknesses found in the technical comparison (such as when a measured parameter was close to the lower limit defined by the monitor based setup) and to make a measurement of the usability of the VR implementation. The results from the technical comparison showed that the technical requirements were met and in most cases also exceeded. There were however some potential weaknesses revealed during the user tests, which included screen resolution and the field of view. There was one main critical deficiency found during the user tests. This was the lack of interaction with the aircraft as users were only able to interact with the flight stick and throttle lever. While this enabled the users to control many aspects of the aircraft (by using buttons and other controls fitted on the flight stick/throttle) in a training scenario a user also has to be able to interact with other switches and/or monitors in the cockpit. This was however a known limitation of the implementation and thus didn’t affect the tested parts of the simulator. The user tests also confirmed that the resolution was a potential problem, but that the overall usability was high. Thus the VR implementation had potential for use in a pilot training simulator, if the critical issues found during the user tests were solved.

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  • 296.
    Gustafsson, Marcus
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Holm, Oscar
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Fuzz testing for design assurance levels2017Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    With safety critical software, it is important that the application is safe and stable. While this software can be quality tested with manual testing, automated testing has the potential to catch errors that manual testing will not. In addition there is also the possibility to save time and cost by automating the testing process. This matters when it comes to avionics components, as much time and cost is spent testing and ensuring the software does not crash or behave faulty. This research paper will focus on exploring the usefulness of automated testing when combining it with fuzz testing. It will also focus on how to fuzzy test applications classified into DAL-classifications.

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  • 297.
    Gustavsson, Johan
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Zenterio.
    A Comparative Study of Automated Test Explorers2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    D ̊a v ̊ara moderna datasystem blir allt mer komplicerade,  ̈okar detta st ̈andigtbehovet av rigor ̈osa tester f ̈or att s ̈akerst ̈alla kvaliteten p ̊a den slutgiltiga pro-dukten. Det h ̈ar inneb ̈ar dock att kostnaden f ̈or att utf ̈ora testerna ocks ̊ao  ̈ kar. F ̈or att f ̈ors ̈oka hitta en l ̈osning p ̊a det h ̈ar problemet har forsknin-gen under senare tid arbetat med att ta fram automatiserade metoder atttesta mjukvarusystem. I den h ̈ar uppsatsen har olika algoritmer, f ̈or attutforska och testa ett system, implementerats och utv ̈arderats. D ̈arut ̈overhar ocks ̊a en grupp algoritmer implementerats som ska kunna isolera vilkainteraktioner med ett system som f ̊ar det att fallera.  ̈aven dessa algoritmerhar utv ̈arderats och testats mot varandra. Resultatet fr ̊an det f ̈orsta ex-perimentet var tv ̊a explorers, h ̈ar kallade DeBruijn och LStarExplorer, somvisade sig vara b ̈attre  ̈an de andra. Den f ̈orsta av dessa anv ̈ande en DeBruijn-sekvens f ̈or att hitta felen, medan den andra anv ̈ande en L*-algoritm f ̈or attbygga upp en FSM  ̈over systemet. Den h ̈ar FSM:en kunde sedan anv ̈andasf ̈or att mer precist beskriva n ̈ar felet uppstod. Resultatet fr ̊an det andraexperimentet var tv ̊a reducers, vilka b ̊ada f ̈ors ̈okte  ̊aterskapa fel genom attf ̈orst applicera interaktioner som ursprungligen utf ̈ordes percis innan feletuppstod. Om felet inte kunde  ̊aterskapas p ̊a detta s ̈att, fortsatte de medatt applicera interaktioner l ̈angre bort tills felet kunde  ̊aterskapas. Ut ̈overdetta inneh ̊aller uppsatsen ocks ̊a beskrivningar av ramverken som anv ̈andsf ̈or att k ̈ora de olika strategierna.

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  • 298.
    Ha, Soonhoi
    et al.
    Seoul Natl Univ, South Korea.
    Eles, Petru Ion
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    2018 Embedded Systems Week (ESWEEK) in Torino2019Ingår i: IEEE design & test, ISSN 2168-2356, E-ISSN 2168-2364, Vol. 36, nr 1, s. 68-69Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 299.
    Ha, Soonhoi
    et al.
    Seoul Natl Univ, South Korea.
    Eles, Petru Ion
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Editorial2018Ingår i: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, ISSN 0278-0070, E-ISSN 1937-4151, Vol. 37, nr 11, s. 2187-2187Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 300.
    Ha, Soonhoi
    et al.
    Seoul National University, South Korea.
    Teich, Jürgen
    Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany.
    Haubelt, Christian
    Universität Rostock, Germany.
    Glaß, Michael
    Ulm University, Germany.
    Mitra, Tulika
    National University of Singapore, Singapore.
    Dömer, Rainer
    University of California, Irvine, USA.
    Eles, Petru
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Shrivastava, Aviral
    Arizona State University, USA.
    Gerstlauer, Andreas
    The University of Texas at Austin, USA.
    Bhattacharyya, Shuvra S.
    University of Maryland, USA; Tampere University of Technology, Finland.
    Introduction to Hardware/Software Codesign2017Ingår i: Handbook of Hardware/Software Codesign / [ed] Soonhoi Ha, Jürgen Teich, Springer Netherlands, 2017Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Hardware/Software Codesign (HSCD) is an integral part of modern Electronic System Level (ESL) design flows. This chapter will review important aspects of hardware/software codesign flows, summarize the historical evolution of codesign techniques, and subsequently summarize each of its major branches of research and achievements that later will be presented in detail by different parts of this Handbook of Hardware/Software Codesign.

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