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  • 51.
    Aminifar, Amir
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Samii, Soheil
    Linköpings universitet, Tekniska högskolan. 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.
    Cervin, Anton
    Dept. of Automatic Control, Lund University, Sweden.
    Designing High-Quality Embedded Control Systems with Guaranteed Stability2012Inngår i: 33rd IEEE Real-Time Systems Symposium (RTSS 2012, 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many embedded systems comprise several controllers sharing available resources. It is well known that such resource sharing leads to complex timing behavior that degrades the quality of control, and more importantly, can jeopardize stability in the worst-case, if not properly taken into account during design. Although stability of the control applications is absolutely essential, a design flow driven by the worst-case scenario often leads to poor control quality due to the significant amount of pessimism involved and the fact that the worst-case scenario occurs very rarely. On the other hand, designing the system merely based on control quality, determined by the expected (average-case) behavior, does not guarantee the stability of control applications in the worst-case. Therefore, both control quality and worst-case stability have to be considered during the design process, i.e., period assignment, task scheduling, and control-synthesis. In this paper, we present an integrated approach for designing high-quality embedded control systems, while guaranteeing their stability.

  • 52.
    Aminifar, Amir
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Tabuada, Paulo
    University of California at Los Angeles, USA.
    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.
    Self-Triggered Controllers and Hard Real-Time Guarantees2016Inngår i: PROCEEDINGS OF THE 2016 DESIGN, AUTOMATION & TEST IN EUROPE CONFERENCE & EXHIBITION (DATE), Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 636-641Konferansepaper (Fagfellevurdert)
    Abstract [en]

    It is well known that event-triggered and self-triggered controllers implemented on dedicated platforms can provide the same performance as the traditional periodic controllers, while consuming considerably less bandwidth. However, since the majority of controllers are implemented by software tasks on shared platforms, on one hand, it might no longer be possible to grant access to the event-triggered controller upon request. On the other hand, due to the seemingly irregular requests from self-triggered controllers, other applications, while in reality schedulable, may be declared unschedulable, if not carefully analyzed. The schedulability and response-time analysis in the presence of self-triggered controllers is still an open problem and the topic of this paper.

  • 53.
    Amlinger, Anton
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    An Evaluation of Clustering and Classification Algorithms in Life-Logging Devices2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Using life-logging devices and wearables is a growing trend in today’s society. These yield vast amounts of information, data that is not directly overseeable or graspable at a glance due to its size. Gathering a qualitative, comprehensible overview over this quantitative information is essential for life-logging services to serve its purpose.

    This thesis provides an overview comparison of CLARANS, DBSCAN and SLINK, representing different branches of clustering algorithm types, as tools for activity detection in geo-spatial data sets. These activities are then classified using a simple model with model parameters learned via Bayesian inference, as a demonstration of a different branch of clustering.

    Results are provided using Silhouettes as evaluation for geo-spatial clustering and a user study for the end classification. The results are promising as an outline for a framework of classification and activity detection, and shed lights on various pitfalls that might be encountered during implementation of such service.

  • 54.
    Anders, Söderholm
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Justus, Sörman
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    GPU-accelleration of image rendering and sorting algorithms with the OpenCL framework2016Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    Today's computer systems often contains several different processing units aside from the CPU. Among these the GPU is a very common processing unit with an immense compute power that is available in almost all computer systems. How do we make use of this processing power that lies within our machines? One answer is the OpenCL framework that is designed for just this, to open up the possibilities of using all the different types of processing units in a computer system. This thesis will discuss the advantages and disadvantages of using the integrated GPU available in a basic workstation computer for computation of image processing and sorting algorithms. These tasks are computationally intensive and the authors will analyze if an integrated GPU is up to the task of accelerating the processing of these algorithms. The OpenCL framework makes it possible to run one implementation on different processing units, to provide perspective we will benchmark our implementations on both the GPU and the CPU and compare the results. A heterogeneous approach that combines the two above mentioned processing units will also be tested and discussed. The OpenCL framework is analyzed from a development perspective and what advantages and disadvantages it brings to the development process will be presented.

  • 55.
    Anderson, Jonathan
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Visualisation of data from IoT systems: A case study of a prototyping tool for data visualisations2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The client in this study, Attentec, has seen an increase in the demand for services connected to Internet of things systems. This study is therefore examining if there is a tool that can be a used to build fast prototype visualisations of data from IoT systems to use as a tool in their daily work.

    The study started with an initial phase with two parts. The first part was to get better knowledge of Attentec and derive requirements for the tool and the second part was a comparison of prototyping tools for aiding in development of data visualisations. Apache Zeppelin was chosen as the most versatile and suitable tool matching the criteria defined together with Attentec. Following the initial phase a pre-study containing interviews to collect empirical data on how visualisations and IoT projects had been implemented previously at Attentec were performed. This lead to the conclusion that geospatial data and NoSQL databases were common for IoT projects. A technical investigation was conducted on Apache Zeppelin to answer if there were any limits in using the tool for characteristics common in IoT system. This investigation lead to the conclusion that there was no support for plotting data on a map.

    The first implementation phase implemented support for geospatial data by adding a visualisation plug-in that plotted data on a map. The implementation phase was followed by an evaluation phase in which 5 participants performed tasks with Apache Zeppelin to evaluate the perceived usability of the tool. The evaluation was performed using a System Usability Scale and a Summed Usability Metric as well as interviews with the participants to find where improvements could be made. From the evaluation three main problems were discovered, the import and mapping of data, more feature on the map visualisation plug-in and the creation of database queries. The first two were chosen for the second iteration where a script for generating the code to import data was developed as well as improvements to the geospatial visualisation plug-in. A second evaluation was performed after the changes were made using similar tasks as in the first to see if the usability was improved between the two evaluations. The results of the Summed Usability Metric improved on all tasks and the System Usability Scale showed no significant change. In the interviews with the participants they all responded that the perceived usability had improved between the two evaluations suggesting some improvement.

  • 56.
    Andersson, Anders
    et al.
    Swedish National Road and Transport Research Institute, Sweden.
    Buffoni, Lena
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Powertrain Model Assessment for Different Driving Tasks through Requirement Verification2018Inngår i: The 9th EUROSIM Congress on Modelica and Simulation, 2018, s. 721-727Konferansepaper (Fagfellevurdert)
    Abstract [en]

    For assessing whether a system model is a good candidate for a particular simulation scenario or choosing the best system model between multiple design alternatives it is important to be able to evaluate the suitability of the system model. In this paper we present a methodology based on finite state machine requirements verifying system behaviour in a Modelica environment where the intended system model usage is within a moving base driving simulator. A use case illustrate the methodology with a Modelica powertrain system model using replaceable components and measured data from a Golf V. The achieved results show the importance of context of requirements and how users are assisted in finding system model issues. 

  • 57.
    Andersson, Anders
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten. Swedish National Road and Transportation Research Institute.
    Fritzson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Models for Distributed Real-Time Simulation in a Vehicle Co-Simulator Setup2013Inngår i: Proceedings of the 5th International Workshop on Equation-Based Object-Oriented Modeling Languages and Tools; April 19, University of Nottingham, Nottingham, UK / [ed] Henrik Nilsson, Linköping: Linköping University Electronic Press, 2013, Vol. 84, s. 131-139Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A car model in Modelica has been developed to be used in a new setup for distributed real-time simulation where a moving base car simulator is connected with a real car in a chassis dynamometer via a 500m fiber optic communication link. The new co-simulator set-up can be used in a number of configurations where hardware in the loop can be interchanged with software in the loop. The models presented in this paper are the basic blocks chosen for modeling the system in the context of a distributed real-time simulation; estimating parameters for the powertrain model; the choice of numeric solver; and the interaction with the solver for real-time properties.

  • 58.
    Andersson, Daniel
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Integrated Test Environment2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    To implement a command line interpreter is normally an easy task. The task getsharder when adding requirements of multi instance functions and the system is torun on a multi-processor security critical embedded system. This thesis describesa first iteration of the system development. The project behind the thesis consistsof requirement elicitation, design, implementation and unit testing. The resultfrom the project is a working first version of the system.

  • 59.
    Andersson, Filip
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Fault Diagnosis in Distributed Simulation Systems over Wide Area Networks using Active Probing2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

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

  • 60.
    Andersson, Henrik
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Knowledge management and throughput optimization in large-scale software development2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

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

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

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

  • 61.
    Andersson, Jonas
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Using React Native and AWS Lambda for cross-platform development in a startup2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

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

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

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

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

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

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

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

  • 62.
    Andersson, Karl
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Mapping out dependencies in network components in critical infrastructure2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

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

  • 63.
    Andersson, Simon
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Energy Consumption of 3G Transmissions for Instant Messaging on Mobile Devices2013Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    A recent surge in the usage of instant messaging (IM) applications on mobile devices has brought the energy efficiency of those applications into the light. We are entering an era where IM applications are changing the message communication on mobile devices, beginning to overtake SMS messages and even phone calls in some cases. Smartphones experience a tremendous increase of data transmissions through wireless interfaces. As illustrated in this work, today's IM applications differ vastly in energy consumption when using the third generation (3G) cellular communication. This thesis focuses on studying the 3G transmission energy footprint of IM applications at the handset level. The energy cost of a common feature used in IM applications that informs that the user is currently typing a response ('typing notify'), is evaluated. The feature is shown to incur a great increase in energy cost compared to the base chat function, ranging from an increase of 43 % to 117 %. The work also proposes a bundle technique that aggregates chat messages over time reducing the energy consumption at the cost of delay for the user. The results show that the bundle technique can save up to 47 % in energy consumption while still keeping the chat function. For the evaluation, conversations collected from a popular IM application are used.

  • 64.
    Andréasson, Dan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Morja, Daniel
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Rekonstruktion och optimering av laddningstid för en webbsida i Ruby on Rails2015Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [sv]

    Många verksamheter representeras idag på internet i omodern stil vilket kan påverka besökarens uppfattning om verksamheten negativt. I detta arbete har en webbsida rekonstruerats. Webbsidan tillhör en förening med verksamhet inom gaming och esport. Rekonstruktionen är till för att ge besökare en klar bild av vad föreningens huvudverksamhet är och för att integrera streamingtjänsten Twitch för att ge besökare ytterligare en anledning att återbesöka sidan. Dessutom har laddningstiden för startsidan optimerats för att ge bättre besökupplevelse. Med hjälp av Redis och metoden Eager loading visar arbetet hur man kan sänka laddningstiden på en webbsida.

  • 65.
    Aragon, Elena
    et al.
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Jimenez, Juan M.
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Maghazeh, Arian
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Rasmusson, Jim
    Sony Mobile Communications, Sweden.
    Bordoloi, Unmesh D.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Pattern matching in OpenCL: GPU vs CPU energy consumption on two mobile chipsets2014Inngår i: Proceedings of the International Workshop / OpenCL 2013 & 2014 (IWOCL '14), ACM Digital Library, 2014, s. Article No. 5-Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Adaptations of the Aho-Corasick (AC) algorithm on high performance graphics processors (also called GPUs) have garnered increasing attention in recent years. However, no results have been reported regarding their implementations on mobile GPUs. In this paper, we show that implementing a state-of-the-art Aho-Corasick parallel algorithm on a mobile GPU delivers significant speedups. We study a few implementation optimizations some of which may seem counter-intuitive to standard optimizations for high-end GPUs. More importantly, we focus on measuring the energy consumed by different components of the OpenCL application rather than reporting the aggregate. We show that there are considerable energy savings compared to the CPU implementation of the AC algorithm.

  • 66.
    Arman, Sheikh Ali
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    RESTful Mobile Application for Android: Mobile Version of Inspectera Online2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Web service-based mobile applications have become emergent in the recent years. Representational State Transfer (REST) architecture style introduced the concept of Resource Oriented Architecture (ROA), which has been widely used for building applications for all platforms. This master’s thesis designs and develops a Web service-based mobile application for Android platform following the constraints of REST architectural style. It also proposes an authentication model for RESTful applications. The master’s thesis is completed at the company Inspectera HK AB in Norrköping, Sweden. The developed application is called the “Mobile version of Inspectera Online.” 

  • 67.
    Artchounin, Daniel
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Tuning of machine learning algorithms for automatic bug assignment2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In software development projects, bug triage consists mainly of assigning bug reports to software developers or teams (depending on the project). The partial or total automation of this task would have a positive economic impact on many software projects. This thesis introduces a systematic four-step method to find some of the best configurations of several machine learning algorithms intending to solve the automatic bug assignment problem. These four steps are respectively used to select a combination of pre-processing techniques, a bug report representation, a potential feature selection technique and to tune several classifiers. The aforementioned method has been applied on three software projects: 66 066 bug reports of a proprietary project, 24 450 bug reports of Eclipse JDT and 30 358 bug reports of Mozilla Firefox. 619 configurations have been applied and compared on each of these three projects. In production, using the approach introduced in this work on the bug reports of the proprietary project would have increased the accuracy by up to 16.64 percentage points.

  • 68.
    Arvanitaki, Antonia
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Pappas, Nikolaos
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Mohapatra, Parthajit
    Indian Inst Technol Tirupati, India.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Delay Performance of a Two-User Broadcast Channel with Security Constraints2018Inngår i: 2018 GLOBAL INFORMATION INFRASTRUCTURE AND NETWORKING SYMPOSIUM (GIIS), IEEE , 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we consider the two-user broadcast channel with security constraints. We assume that one of the receivers has a secrecy constraint; i.e., its packets need to be kept secret from the other receiver. The receiver with secrecy constraint has full-duplex capability to transmit a jamming signal to increase its secrecy. We derive the average delay per packet and provide simulation and numerical results, where we compare different performance metrics for the cases when the legitimate receiver performs successive decoding and when both receivers treat interference as noise.

  • 69.
    Arvid, Johnsson
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Analysis of GPU accelerated OpenCL applications on the Intel HD 4600 GPU2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    GPU acceleration is the concept of accelerating the execution speed of an application by running it on the GPU. Researchers and developers have always wanted to achieve greater speed for their applications and GPU acceleration is a very common way of doing so. This has been done a long time for highly graphical applications using powerful dedicated GPUs. However, researchers have become more and more interested in using GPU acceleration on everyday applications. Moreover now a days more or less every computer has some sort of integrated GPU which often is underutilized. The integrated GPUs are not as powerful as dedicated ones but they have other benefits such as a lower power consumption and faster data transfer. Therefore this thesis’ purpose was to examine whether the integrated GPU Intel HD 4600 can be used to accelerate the two applications Image Convolution and sparse matrix vector multiplication (SpMV). This was done by analysing the code from a previous thesis which produced some unexpected results as well as a benchmark from the OpenDwarf’s benchmark suite. The Intel HD 4600 was able to speedup both Image Convolution and SpMV by about two times compared to running them on the Intel i7-4790. However, the SpMV implementation was not well suited for the GPU meaning that the speedup was only observed on ideal input configurations.

  • 70.
    Arvidsson, Peter
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    3D Visualization Package for OpenModelica2012Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    A 3D representation of a physical phenomena is often a good way to present it. It’s often easier to see an event in an animation rather than just read data tables. The goal of this thesis is to create an application that visualizes a physical simulation in Modelica. This thesis explains how the OMVisualize application was developed. To create the OMVisualize the OpenSceneGraph library was used. The OpenSceneGraph is a 3D package written in C++ that is used in many different applications from game to scientific applications.

  • 71.
    Asani, Golnaz
    et al.
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system.
    Zadegan, Farrokh Ghani
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system. Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Ingelsson, Urban
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system.
    Carlsson, Gunnar
    Ericsson, Linköping, Sweden.
    Larsson, Erik
    Linköpings universitet, Institutionen för datavetenskap, ESLAB - Laboratoriet för inbyggda system.
    Test Scheduling with Constraints for IEEE P1687 (poster)2011Inngår i: International Test Conference (ITC11), Anaheim, CA, USA, September 18-23, 2011., 2011Konferansepaper (Fagfellevurdert)
  • 72.
    Asghar, Adeel
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Pfeiffer, Andreas
    DLR Institute of System Dynamic and Control, Wessling, Tyskland.
    Palanisamy, Arunkumar
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Mengist, Alachew
    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.
    Pop, Adrian
    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.
    Automatic Regression Testing of Simulation Models and Concept for Simulation of Connected FMUs in PySimulator2015Inngår i: Proceedings of the 11th International Modelica Conference: Versailles, France, September 21-23, 2015 / [ed] Peter Fritzson, Hilding Elmqvist, Linköping, 2015, s. 671-679Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Modelica and FMI tool ecosystem is growing each year with new tools and methods becoming available. The open Modelica standard promises portability but it is important to ensure that a certain model behaves the same in different Modelica tools or in a different version of the same tool. It is also very important (for model evolution) to check that a new version of the same model produces comparable results. Finally, it is desirable to verify that a model exported in FMU form from a Modelica tool gives exactly the same results as the original model. This paper presents a framework for automatic regression testing as part of PySimulator which provides an efficient and concise way of testing if a model or a range of models behaves in the same way in several tools or versions of a tool by checking that the results produced are essentially identical. The FMI standard has been adopted by many tool vendors and is growing in popularity each year. This paper proposes a concept for building and simulating a system made from connected FMUs generated by different tools. The FMUs for Co-Simulation can be connected together using a GUI. The system model built graphically in this way can be saved for later use or simulated directly inside PySimulator. Active development is going on to support simulation of connected FMUs for Model Exchange.

  • 73.
    Askling, Kim
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Application of Topic Models for Test Case Selection: A comparison of similarity-based selection techniques2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Regression testing is just as important for the quality assurance of a system, as it is time consuming. Several techniques exist with the purpose of lowering the execution times of test suites and provide faster feedback to the developers, examples are ones based on transition-models or string-distances. These techniques are called test case selection (TCS) techniques, and focuses on selecting subsets of the test suite deemed relevant for the modifications made to the system under test.

    This thesis project focused on evaluating the use of a topic model, latent dirichlet allocation, as a means to create a diverse selection of test cases for coverage of certain test characteristics. The model was tested on authentic data sets from two different companies, where the results were compared against prior work where TCS was performed using similarity-based techniques. Also, the model was tuned and evaluated, using an algorithm based on differential evolution, to increase the model’s stability in terms of inferred topics and topic diversity.

    The results indicate that the use of the model for test case selection purposes was not as efficient as the other similarity-based selection techniques studied in work prior to thist hesis. In fact, the results show that the selection generated using the model performs similar, in terms of coverage, to a randomly selected subset of the test suite. Tuning of the model does not improve these results, in fact the tuned model performs worse than the other methods in most cases. However, the tuning process results in the model being more stable in terms of inferred latent topics and topic diversity. The performance of the model is believed to be strongly dependent on the characteristics of the underlying data used to train the model, putting emphasis on word frequencies and the overall sizes of the training documents, and implying that this would affect the words’ relevance scoring to the better.

  • 74.
    Asplund, Mikael
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Automatically proving the correctness of vehicle coordination2018Inngår i: ICT Express, ISSN 2405-9595, Vol. 4, nr 1, s. 51-54Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the next generation of road-based transportation systems, where vehicles exchange information and coordinate their actions, a major challenge will be to ensure that the interaction rules are safe and lead to progress. In this paper we address the problem of automatically verifying the correctness of such distributed vehicular coordination protocols. We propose a novel modeling approach for communicating mobile entities based on the concept of satisfiability modulo theories (SMT). We apply this method to an intersection collision avoidance protocol and show how the method can be used to investigate the settings under which such a protocol achieves safety and progress.

  • 75.
    Asplund, Mikael
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Combining Detection and Verification for Secure Vehicular Cooperation Groups2019Inngår i: ACM Transactions on Cyber-Physical Systems, ISSN 2378-962X, Vol. 4, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Coordinated vehicles for intelligent traffic management are instances of cyber-physical systems with strict correctness requirements. A key building block for these systems is the ability to establish a group membership view that accurately captures the locations of all vehicles in a particular area of interest. In this article, we formally define view correctness in terms of soundness and completeness and establish theoretical bounds for the ability to verify view correctness. Moreover, we present an architecture for an online view detection and verification process that uses the information available locally to a vehicle. This architecture uses an SMT solver to automatically prove view correctness (if possible). We evaluate this architecture using both synthetic and trace-based scenarios and demonstrate that the ability to verify view correctness is on par with the ability to detect view violations.

  • 76.
    Asplund, Mikael
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Model-based Membership Verification in Vehicular Platoons2015Inngår i: Proceedings: 2015 45th Annual IEEE/IFIP International Conference on Dependable Systems and Networks Workshops , IEEE Computer Society, 2015, s. 125-132Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cooperative vehicular systems have the potentialto significantly increase traffic efficiency and safety. However,they also raise the question of to what extent information thatis received from other vehicles can be trusted. In this paperwe present a novel approach for increasing the trustworthinessof cooperative driving through a model-based approach forverifying membership views in vehicular platoons. We define aformal model for platoon membership, cooperative awarenessclaims, and membership verification mechanisms. With the helpof a satisfiability solver, we are able to quantitatively analysethe impact of different system parameters on the verifiability ofreceived information. Our results demonstrate the importance ofcross validating received messages, as well as the surprising diffi-culty in establishing correct membership views despite powerfulverification mechanisms.

  • 77.
    Asplund, Mikael
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Poster: Securing Vehicular Platoon Membership2014Inngår i: Proceedings of IEEE Vehicular Networking Conference (VNC), IEEE Computer Society, 2014, s. 119-120Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Vehicular platoons have the potential to bring considerable fuel-savings and increase traffic efficiency. A key component for the next generation platoon systems is a secure membership component which can accommodate membership changes in a dynamic and potentially hostile environment. In this poster paper we analyse the conditions for creating a secure membership protocol which is resilient to attacks and faults in the communication protocols.

  • 78.
    Asplund, Mikael
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Lövhall, Jakob
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    In-store payments using Bitcoin2018Inngår i: 9th IFIP International Conference on New Technologies, Mobility and Security (NTMS), IEEE, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The possibility of in-store payments would further increase the potential usefulness of cryptocurrencies. However, this would require much faster transaction verification than current solutions provide (one hour for Bitcoin) since customers are likely not prepared to wait a very long time for their purchase to be accepted by a store. We propose a solution for enabling in-store payments with waiting times in the order of a few seconds, which is still compatible with the current Bitcoin protocol. The idea is based on a payment card in combination with a protocol for ensuring that losing a card does not mean losing the money on it. We analyse the required transaction verification delay and also the potentially added risks that the solution brings compared to current systems.

  • 79.
    Asplund, Mikael
    et al.
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Lövhall, Jakob
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Villani, Emilia
    Auronatics Institute of Technology, Brazil.
    Specification, Implementation and Verification of Dynamic Group Membership for Vehicle Coordination2017Inngår i: Dependable Computing (PRDC), 2017 IEEE 22nd Pacific Rim International Symposium on, IEEE, 2017, s. 321-328Konferansepaper (Fagfellevurdert)
    Abstract [en]

    New advanced traffic management solutions with fully or semi-autonomous vehicles that communicate over a wireless interface to coordinate their driving decisions create new challenges in distributed computing. In this paper we address the problem of dynamic group membership in three stages. First, we propose three criteria to specify correctness and performance of the group views created by such algorithms in terms of soundness, completeness and freshness. Second, we develop a group membership protocol tailored for vehicular coordination. Finally, we show through simulation and model-based verification that the protocol does indeed meet the criteria and provide at least 95% perfect group membership views under as adverse conditions as 70% packet loss or very high churn rate.

  • 80.
    Asplund, Mikael
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Analysing Delay-tolerant Networks with Correlated Mobility2012Inngår i: Ad-hoc, Mobile, and Wireless Networks: 11th International Conference, ADHOC-NOW 2012, Belgrade, Serbia, July 9-11, 2012. Proceedings / [ed] Xiang-Yang Li, Symeon Papavassiliou, Stefan Ruehrup, Springer , 2012, s. 83-97Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This book constitutes the refereed proceedings of the 11th International Conference on Ad-hoc, Mobile, and Wireless Networks, ADHOC-NOW 2012 held in Belgrade, Serbia, July 9-11, 2012. The 36 revised full papers presented were carefully reviewed and selected from 76 submissions. The accepted papers cover a wide spectrum of traditional networking topics ranging from routing to the application layer, to localization in various networking environments such as wireless sensor and ad-hoc networks, and give insights in a variety of application areas.

  • 81.
    Asplund, Mikael
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Attitudes and Perceptions of IoT Security in Critical Societal Services2016Inngår i: IEEE Access, E-ISSN 2169-3536, Vol. 4, s. 2130-2138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A quiet revolution that impacts several sectors, ranging over transport, home automation, energy, industrial control, and health services is undergoing with addition of new networked devices leading to enhanced services. In this paper, we aim to identify information security requirements that are common over several (vertical) sectors, and in particular, ones that impact critical societal services, namely, the energy, water, and health management systems. We present the results of an interview-based study where actors in these sectors were asked about their perceptions and attitudes on the security of Internet of Things (IoT). We set these perceptions and attitudes in context through a literature review of IoT security, and relate to current challenges in this area. This paper demonstrates that despite an overall optimistic view on IoT in critical societal services, there is a lack of consensus on risks related to IoT security.

  • 82.
    Asplund, Mikael
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Rapid selection and dissemination of urgent messages over delay-tolerant networks (DTNs)2015Inngår i: Advances in Delay-Tolerant Networks (DTNs): Architecture and Enhanced Performance / [ed] J. Rodrigues, Elsevier, 2015, s. 187-203Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Today many new applications are emerging that take advantage of wireless communication in handheld and embedded devices. Some of these emerging applications, such as information sharing in vehicular systems, have strong requirements for timely message dissemination, even if the network is not always 100% connected. In this chapter we discuss message differentiation mechanisms that can be used in intermittently connected networks to improve delivery and latency properties when messages have a limited time to live in the network. We present a simulation-based study on a large-scale vehicular scenario comparing different prioritisation mechanisms for a partition-tolerant manycast protocol. We show that negative effects of overloads can be significantly reduced by using information within the message about how far it has spread and how much time is remaining.

  • 83.
    Asplund, Mikael
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Worst-case latency of broadcast in intermittently connected networks2012Inngår i: International Journal of Ad Hoc and Ubiquitous Computing, ISSN 1743-8225, E-ISSN 1743-8233, Vol. 11, nr 2-3, s. 125-138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Worst-case latency is an important characteristic of information dissemination protocols. However, in sparse mobile ad hoc networks where end-to-end connectivity cannot be achieved and store-carry-forward algorithms are needed, such worst-case analyses have not been possible to perform on real mobility traces due to lack of suitable models. We propose a new metric called delay expansion that reflects connectivity and reachability properties of intermittently connected networks. Using the delay expansion, we show how bounds on worst-case latency can be derived for a general class of broadcast protocols and a wide range of real mobility patterns. The paper includes theoretical results that show how worst-case latency can be related with delay expansion for a given mobility scenario, as well as simulations to validate the theoretical model.

  • 84.
    Avdic, Kenan
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    On-chip Pipelined Parallel Mergesort on the Intel Single-Chip Cloud Computer2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

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

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

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

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

  • 85.
    Avdic, Kenan
    et al.
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Melot, Nicolas
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Kessler, Christoph
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Keller, Jörg
    FernUniversität in Hagen.
    Pipelined parallel sorting on the Intel SCC2011Inngår i: Fourth Swedish Workshop on Multi-Core Computing MCC-2011: November 23-25, 2011, Linköping University, Linköping, Sweden / [ed] Christoph Kessler, Linköping: Linköping University , 2011, Vol. S. 96-101, s. 96-101Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The Single-Chip Cloud Computer (SCC) is an experimental processor created by Intel Labs. It comprises 48 Intel-IA32 cores linked by an on-chip high performance mesh network, as well as four DDR3 memory controllers to access an off-chip main memory. We investigate the adaptation of sorting onto SCC as an algorithm engineering problem. We argue that a combination of pipelined mergesort and sample sort will fit best to SCC's architecture. We also provide a mapping based on integer linear programming to address load balancing and latency considerations. We describe a prototype implementation of our proposai together with preliminary runtime measurements, that indicate the usefulness of this approach. As mergesort can be considered as a representative of the class of streaming applications, the techniques deveioped here should also apply to the other problems in this class, such as many applications for parallel embedded systems, i.e. MPSoC. 

  • 86.
    Azari, Leila
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Domain Specific Modeling Support for ArCon2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

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

  • 87.
    Aziz Abdulla, Parosh
    et al.
    Uppsala University, Sweden.
    Faouzi Atig, Mohamed
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academic Sinica, Taiwan.
    Holik, Lukas
    Brno University of Technology, Czech Republic.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Rummer, Philipp
    Uppsala University, Sweden.
    Stenman, Jari
    Uppsala University, Sweden.
    Norn: An SMT Solver for String Constraints2015Inngår i: COMPUTER AIDED VERIFICATION, PT I / [ed] Kroening, Daniel, Păsăreanu, Corina S., SPRINGER-VERLAG BERLIN , 2015, Vol. 9206, s. 462-469Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present version 1.0 of the Norn SMT solver for string constraints. Norn is a solver for an expressive constraint language, including word equations, length constraints, and regular membership queries. As a feature distinguishing Norn from other SMT solvers, Norn is a decision procedure under the assumption of a set of acyclicity conditions on word equations, without any restrictions on the use of regular membership.

  • 88.
    Aziz Abdulla, Parosh
    et al.
    Uppsala University, Sweden.
    Faouzi Atig, Mohamed
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academic Sinica, Taiwan.
    Phi Diep, Bui
    Uppsala University, Sweden.
    Holik, Lukas
    Brno University of Technology, Czech Republic.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Rummer, Philipp
    Uppsala University, Sweden.
    Flatten and Conquer A Framework for Efficient Analysis of String Constraints2017Inngår i: ACM SIGPLAN NOTICES, ACM Press, 2017, Vol. 52, nr 6, s. 602-617Konferansepaper (Fagfellevurdert)
    Abstract [en]

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

  • 89.
    Aziz Abdulla, Parosh
    et al.
    Uppsala University, Sweden.
    Haziza, Frederic
    Uppsala University, Sweden.
    Holik, Lukas
    Uppsala University, Sweden; Brno University of Technology, Czech Republic.
    Jonsson, Bengt
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    An integrated specification and verification technique for highly concurrent data structures for highly concurrent data structures2017Inngår i: International Journal on Software Tools for Technology Transfer (STTT), ISSN 1433-2779, E-ISSN 1433-2787, Vol. 19, nr 5, s. 549-563Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 90.
    Backman, Lars
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Why is security still an issue?: A study comparing developers’ software security awareness to existing vulnerabilities in software applications2018Independent thesis Basic level (university diploma), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The need for secure web applications grows ever stronger the more sensitive, personal data makes its’ way onto the Internet. During the last decade, hackers have stolen enormous amounts of data from high profile companies and social institutions. In this paper, we answer the question of why security breaches still occur; Why do programmers write vulnerable code? To answer this question, we conducted a case study on a smaller software development company. By performing penetration tests, surveys and interviews we successfully identified several weaknesses in their product and their way of working, that could lead to security breaches in their application. We also conducted a security awareness assessment and found multiple contributing factors to why these weaknesses occur. Insufficient knowledge, misplaced trust, and inadequate testing policies are some of the reasons why these vulnerabilities appeared in the studied application.

  • 91.
    Banerjee, Abhijeet
    et al.
    National University of Singapore.
    Chong, Lee Kee
    National University of Singapore.
    Chattopadhyay, Sudipta
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Roychoudhury, Abhik
    National University of Singapore.
    Detecting Energy Bugs and Hotspots in Mobile Apps2014Inngår i: FSE 2014: Foundations of Software Engineering, Association for Computing Machinery (ACM), 2014, s. 588-598Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Over the recent years, the popularity of smartphones has increased dramatically. This has lead to a widespread availability of smartphone applications. Since smartphones operate on a limited amount of battery power, it is important to develop tools and techniques that aid in energy-efficient application development. Energy inefficiencies in smartphone applications can broadly be categorized into energy hotspots and energy bugs. An energy hotspot can be described as a scenario where executing an application causes the smartphone to consume abnormally high amount of battery power, even though the utilization of its hardware resources is low. In contrast, an energy bug can be described as a scenario where a malfunctioning application prevents the smartphone from becoming idle, even after it has completed execution and there is no user activity. In this paper, we present an automated test generation framework that detects energy hotspots/bugs in Android applications. Our framework systematically generates test inputs that are likely to capture energy hotspots/bugs. Each test input captures a sequence of user interactions (e.g. touches or taps on the smartphone screen) that leads to an energy hotspot/bug in the application. Evaluation with 30 freely-available Android applications from Google Play/F-Droid shows the efficacy of our framework in finding hotspots/bugs. Manual validation of the experimental results shows that our framework reports reasonably low number of false positives. Finally, we show the usage of the generated results by improving the energy-efficiency of some Android applications.

  • 92.
    Beck-Norén, Gustav
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Cross-platform Development for Wearable Devices2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The market for wearable devices is continuously growing and has seen an in- crease in interest and demand this past year, specifically smartwatch devices. With several big players entering and trying to take place in the market the number of devices and platforms grow. This leads to device and software fragmentation like the one seen in the world of smartphones. In this paper I discuss and compare the two smartwatch platforms Android Wear and Apple Watch in terms of possibilities, limitations and differences. Research is done to find cross-platform development possibilities for these platforms. Extensive theoretical background of both APIs is researched and presented. An app for both smartwatch platforms is developed with integration of the WebSocket protocol to function as a remote control for a Video-On-Demand web service. This is done to showcase the cross-platform possibilities and differences of the platforms. As a result the biggest differences are out- lined and a conclusion is made that cross-platform development for these platforms can be challenging but is possible on certain levels. 

  • 93.
    Bengtsson, Tomas
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Testing and Logic Optimization Techniques for Systems on Chip2012Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Today it is possible to integrate more than one billion transistors onto a single chip. This has enabled implementation of complex functionality in hand held gadgets, but handling such complexity is far from trivial. The challenges of handling this complexity are mostly related to the design and testing of the digital components of these chips.

    A number of well-researched disciplines must be employed in the efficient design of large and complex chips. These include utilization of several abstraction levels, design of appropriate architectures, several different classes of optimization methods, and development of testing techniques. This thesis contributes mainly to the areas of design optimization and testing methods.

    In the area of testing this thesis contributes methods for testing of on-chip links connecting different clock domains. This includes testing for defects that introduce unacceptable delay, lead to excessive crosstalk and cause glitches, which can produce errors. We show how pure digital components can be used to detect such defects and how the tests can be scheduled efficiently.

    To manage increasing test complexity, another contribution proposes to raise theabstraction level of fault models from logic level to system level. A set of system level faultmodels for a NoC-switch is proposed and evaluated to demonstrate their potential.

    In the area of design optimization, this thesis focuses primarily on logic optimization. Two contributions for Boolean decomposition are presented. The first one is a fast heuristic algorithm that finds non-disjoint decompositions for Boolean functions. This algorithm operates on a Binary Decision Diagram. The other contribution is a fast algorithm for detecting whether a function is likely to benefit from optimization for architectures with a gate depth of three with an XOR-gate as the third gate.

  • 94.
    Benjamin, Andersson
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    En teoretisk och praktisk jämförelse av alternativ till OpenLayers2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Med att de mobila enheterna blir allt mer kraftigare och webbtekniken går allt fortare framåt, så har webbapplikationer börjat blivit ett fullgott alternativ till vanliga nativeapplikationer. Presentera webbkartor med hjälp av ramverket OpenLayers har aldrig varit en större användarupplevelse på  mobil enhet då det är både stort och tungkört för en segare enhet. Samt att de aldrig var tänkte från början att fungera för  touchbaserade enheter, utan de är stöd som  senare har lagts på.

    Därför har jag hittat ett annat fullgott  alternativ till OpenLayers som heter Leaflet, som är anpassat att ha alla funktioner som  man kan kräva av en webbaserad karta och samtidigt fungera i mobila touch enheteter. Leaflet använder alla nya webbtekniker som HTML5 och CSS3 i största möjliga mån för att få sådan bra upplevelse som möjligt.

    Jag gjorde om hela klientdelen av en realtidskarta för blixtar i Leaflet istället, så att den skulle fungera bättre på en mobil enhet än vad den tidigare gjorde. Med denna implementation så visade sig att Leaflet kunde nå upp till alla krav som man kan ställa på en webbaserad karta. Resultatet blev en mycket lättare och snabbare klient med samma funktionalitet som den förra hade.

  • 95.
    Berekovic, Mladen
    et al.
    Technical University of Carolo Wilhelmina Braunschweig, Germany .
    Chakraborty, Samarjit
    Technical University of Munich, Germany .
    Eles, Petru Ion
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Pimentel, Andy D
    University of Amsterdam, Netherlands .
    Editorial Material: Introduction to the Special Section on ESTIMedia082012Inngår i: ACM Transactions on Embedded Computing Systems, ISSN 1539-9087, E-ISSN 1558-3465, Vol. 11, nr 1Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    n/a

  • 96.
    Berg, Emil
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Ad-hoc Routing in Low Bandwidth Environments2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

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

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

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

  • 97.
    Berger, Lutz
    et al.
    Berger IT-COSMOS GmbH, Bavaria, Germany.
    Sjölund, Martin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Thiele, Bernhard
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Code Generation for STM32F4 Boards with Modelica Device Drivers: [Work in Progress]2017Inngår i: Proceedings of the 8th International Workshop on Equation-Based Object-Oriented Modeling Languages and Tools, Association for Computing Machinery (ACM), 2017, s. 77-80Konferansepaper (Fagfellevurdert)
  • 98.
    Berglund, Aseel
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska fakulteten.
    Berglund, Erik
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska fakulteten.
    Siliberto, Fabio
    University of Roma La Sapienza, Italy.
    Prytz, Erik
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Filosofiska fakulteten.
    Effects of Reactive and Strategic Game Mechanics in Motion-based Games2017Inngår i: 2017 IEEE 5TH INTERNATIONAL CONFERENCE ON SERIOUS GAMES AND APPLICATIONS FOR HEALTH (SEGAH), IEEE , 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Motion-based games offer positive effects on physical, social, and mental health for the players and have been common during the past decade, enabled by commercial motion tracking devices. However, little is known about the impact of game mechanics on the player experience, movement, and performance in motion-based games. In this paper we present results from a study with 35 participants comparing two different game mechanics, one reactive and one strategic, for a casual motion-based game. The assumption was that a more strategic mechanic would lead to less movement but more enjoyment. However, there was no significant difference in player experience, performance, or movement between the two game mechanics. In addition, a key aspect for the players preferred game mechanics was the perceived amount of thinking the game mechanic required.

  • 99.
    Berglund, Aseel
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Heintz, Fredrik
    Linköpings universitet, Institutionen för datavetenskap, Artificiell intelligens och integrerad datorsystem. Linköpings universitet, Tekniska högskolan.
    Integrating Soft Skills into Engineering Education for Increased Student Throughput and more Professional Engineers2014Inngår i: Proceedings of LTHs 8:e Pedagogiska Inspirationskonferens (PIK), Lund, Sweden: Lunds university , 2014Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Soft skills are recognized as crucial for engineers as technical work is becoming more and more collaborative and interdisciplinary. Today many engineering educations fail to give appropriate training in soft skills. Linköping University has therefore developed a completely new course “Professionalism for Engineers” for two of its 5-year engineering programs in the area of computer science. The course stretches over the first 3 years with students from the three years taking it together. The purpose of the course is to give engineering students training in soft skills that are of importance during the engineering education as well as during their professional career. The examination is based on the Dialogue Seminar Method developed for learning from experience and through reflection. The organization of the course is innovative in many ways.

  • 100.
    Bergman, Sara
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Permissioned Blockchains and Distributed Databases: A Performance Study2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Blockchain technology is a booming new field in both computer science and economicsand other use cases than cryptocurrencies are on the rise. Permissioned blockchains are oneinstance of the blockchain technique. In a permissioned blockchain the nodes which validatesnew transactions are trusted. Permissioned blockchains and distributed databasesare essentially two different ways for storing data, but how do they compare in terms ofperformance? This thesis compares Hyperledger Fabric to Apache Cassandra in four experimentsto investigate their insert and read latency. The experiments are executed usingDocker on an Azure virtual machine and the studied systems consist of up to 20 logicalnodes. Latency measurements are performed using varying network size and load. Forsmall networks, the insert latency of Cassandra is twice as high as that of Fabric, whereasfor larger networks Fabric has almost twice as high insert latencies as Cassandra. Fabrichas around 40 ms latency for reading data and Cassandra between 150 ms to 250 ms, thusit scales better for reading. The insert latency of different workloads is heavily affected bythe configuration of Fabric and by the Docker overhead for Cassandra. The read latency isnot affected by different workloads for either system.

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