<p>To date, many industrial embedded systems are very large, flexible, and highly configurable software systems, containing millions of lines of code and consisting of hundreds of tasks, many with real-time constraints, being triggered in complex, nested patterns. Furthermore, the temporal dependencies between tasks in such systems are difficult to determine analytically, and they vary the execution time and response time of tasks greatly. We refer to such systems as Complex Real-Time Embedded Systems (CRTES).</p><p>To maintain, analyze and reuse such CRTES is very difficult and expensive, which, nevertheless, offers high business value in response to great concern in industry. Moreover, in such context, not only the functional behavior of systems has to be assured, but also non-functional properties such as the temporal behavior, i.e., Worst-Case Response Time (WCRT) of the adhering tasks in systems has to be known. However, due to high complexity of such systems and the nature of the problem, the exact WCRT of tasks is impossible to find in practice, but may only be bounded. In addition, the existing relatively well-developed theories for modeling and analysis of real-time systems are having problems, which limit their application in the context. In this thesis, we address this challenge, and present a framework for approximate timing analysis of CRTES that provides a tight interval of WCRT estimates of tasks by the usage of three novel contributions.</p><p>The first contribution is a novel statistical approach to WCRT analysis of CRTES. The proposed algorithm combines Extreme Value Theory (EVT) with other statistical methods in order to produce a probabilistic WCRT estimate, using response time data from either Monte Carlo simulations of a detailed model of the system, or time-stamped traces of the real system execution. The focus of the method is to give a WCRT prediction with a given probability of being exceeded, which potentially could be considered as an upper bound on the WCRT estimate in systems, especially in the case where conventional timing analysis methods cannot be applied.</p><p>The second contribution is to introduce a concrete process of formally obtaining the exact value of both Worst-Case Execution Time (WCET) and WCRT of tasks in the system model by using upper-part binary search algorithms together with a timed model checker, after a semantic-preserving model transformation. The underline premise is that the size and complexity of CRTES have to be reduced such that they can be manageable by the model checking tool.</p><p>The third contribution is to apply an optimization algorithm, in this case a meta-heuristic search algorithm, on top of the traditional Monte Carlo simula-tion, which yields substantially better results with respect to tight lower bounds on WCRT estimates of tasks in CRTES.</p><p>In addition, a number of tools have been implemented and used for the evaluation of the research results. These evaluations, using four simulation models depicting two fictive but representative industrial control applications, give clear indication that the proposed methods have the potential to be both applicable and useful in practice.</p>

<p> </p><p>The Hierarchical Scheduling Framework (HSF) has been introduced to enable compositional schedulability analysis and execution of embedded software systems with real-time constraints. In this thesis, we consider a system consisting of a number of semi-independent components called subsystems, and these subsystems are allowed to share logical resources. The HSF provides CPU-time to the subsystems and it guarantees that the individual subsystems respect their allocated CPU budgets. However, if subsystems are allowed to share logical resources, extra complexity with respect to analysis and run-time mechanisms is introduced. In this thesis we address three issues related to hierarchical scheduling of semi-independent subsystems. In the first part, we investigate the feasibility of implementing the hierarchical scheduling framework in a commercial operating system, and we present the detailed figures of various key properties with respect to the overhead of the implementation.</p><p>In the second part, we studied the problem of supporting shared resources in a hierarchical scheduling framework and we propose two different solutions to support resource sharing. The first proposed solution is called SIRAP, a synchronization protocol for resource sharing in hierarchically scheduled open real-time systems, and the second solution is an <em>enhanced overrun mechanism</em>.</p><p>In the third part, we present a resource efficient approach to minimize system load (i.e., the collective CPU requirements to guarantee the schedulability of hierarchically scheduled subsystems). Our work is motivated from a tradeoff between reducing resource locking times and reducing system load. We formulate an optimization problem that determines the resource locking times of each individual subsystem with the goal of minimizing the system load subject to system schedulability. We present linear complexity algorithms to find an optimal solution to the problem, and we prove their correctness</p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p>

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Branched video enables users to interact with the video content and to choose a unique path through that content. With the further development of Virtual Reality (VR) technology the integration of branched video in these systems becomes increasingly convincing. This thesis develops a 360 degree branched video player in Unity Editor and three different user interfaces (UI) tailored for the needs of branched 360 degree video content, both the design and implementation focus on the aspects of usability. To expedite development of the UIs ,a preliminary user study was conducted to identify a promising design direction. From the study it was established that plain buttons with descriptive text attached, anchored in front of the field of view at the time of appearing, was to be preferred for the selection of the subsequent branch. This design was preferred both in a short motion picture and exploratory film setting. However, world-space anchored symbols as depicted to appear transporting the user to that world-space location showed promise in an exploratory video setting. Based on the result of the study and subjective feedback from study participants, additional features was implemented to the user interfaces. Lastly, further development of both features for the user interface, tools regarding the video player, and a follow-up user study are suggested.

After conducting a survey at Linköping University it was shown that few women choose to use protein powder. The same survey also showed that only a fraction of these women possessed knowledge regarding their optimal protein consumption. A web application that sells protein and training related products were therefore developed. This application is designed to have satisfactory navigability and an appealing graphic profile for women. The navigability is intended to, in an efficient manner, eliminate the information gap regarding protein supplements for the intended target group. The web application’s functionality anddesign has been based on scientific theory. Development occurred in iterations after which end users had the possibility to test and leave suggestions for improvements. Improvements to the web application’s navigability has been measured in numerous aspects through all iterations. Time, lostness and certainty have been central for the configuration of the final version of the web application. This report enhances the group’s thesis and exhibits that a web application can have good navigability and be graphically appealing to women. / Efter en enkätundersökning vid Linköpings universitet visade det sig att få aktiva kvinnor väljer att använda proteinpulver. Samma undersökning visade även att endast en bråkdel av kvinnorna hade kunskap kring deras optimala proteinintag. En webbapplikation som säljer protein och träningsrelaterade produkter har därför utvecklats. Denna applikation är utformad för att ha en god navigerbarhet och en tilltalande grafisk profil för kvinnor. Den välutformade navigerbarheten är tänkt att på ett effektivt sätt eliminera de informationsgap kring proteinpulver som finns för målgruppen. Vetenskaplig teori har lagt grunden till webbapplikationens funktionalitet och design. Utveckling har skett i iterationer vid vars slut användare har haft möjlighet att testa och ge förslag på förbättringsmöjligheter. Förbättring kring webbapplikationens navigerbarhet har mätts med flera aspekter genom samtliga iterationer. Tid, lostnessoch säkerhet har varit centrala för utformning av den slutgiltiga versionen. Denna rapport stärker gruppens frågeställning och visar att en webbapplikation kan ha god navigerbarhet samt vara grafisk tilltalande för kvinnor.

The report covers a study made by a project group at Linköping University. The report discusses and analyzes the project that is developing and implementing BikePool, a web application that serves as an online marketplace service for people to rent or lease bikes. The discussion emanates from the aspects of achieving a high simplicity and navigationability in terms of usability because that is desirable attributes from the target group. A survey, distributed among a number of students, at the Linköping University lies as a foundation of the project. What is more, it showed the fundamental necessity of what the core business BikePool tries to attain. Additionally, the outcome of the survey was utilized to form an original prototype that was to be used in the development process. The project group embraced an iterative working method by executing continuous user tests, collecting the emitted information in order to answer the affirmed question formulation. Furthermore, the report discusses and motivates selected technical solutions to substantiate the project goal and purpose. With user tests and a thoroughgoing discussion the conclusion could be drawn that by implementing a web application considering the color and placement of elements and removing noncrucial elements as well as focusing on single-age design, the web application achieves the aspects high navigationability and simplicity in terms of usability.

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Strong authentication and secure communication of sensitive medical data are crucial parts when empowering patients by giving them access to data stored in healthcare systems. Through the use of a mobile application and device patients access relevant personal health information and thus bringing more control over their diseases and empower them to, for instance, make long-lasting lifestyle changes. This thesis presents the communication model SETHER, an approach to manage secure transfer of patient data between healthcare systems and applications running on mobile devices, based on SAML and OAuth. From this model a proof of concept prototype was developed using API Gateway to connect to the National Service Platform, an infrastructure that interconnects most healthcare systems in Sweden. The results indicate that using SETHER as a model for communication, a secure transfer of patient data between patients and care givers is possible. The advantages of this is a secure single sign-on user experience to access patient data through a nationwide system independent on the healthcare system the caregivers are using. Future work includes developing mobile patient applications, using SETHER to connect patient with their caregivers and providing tools to empower patients in their everyday life.

New trends such as the internet-of-things and smart homes push the demands for energy-efficiency. Choosing energy-efficient hardware, however, often comes as a trade-off to high-performance. In order to strike a good balance between the two, we propose software solutions to tackle the performance bottlenecks of small and energy-efficient processors. One of the main performance bottlenecks of processors is the discrepancy between processor and memory speed, known as the memory wall. While the processor executes instructions at a high pace, the memory is too slow to provide data in a timely manner, if data has not been cached in advance. Load instructions that require an access to memory are thereby referred to as long-latency or delinquent loads. Long latencies caused by delinquent loads are putting a strain on small processors, which have few or no resources to effectively hide the latencies. As a result, the processor may stall. In this thesis we propose compile-time transformation techniques to mitigate the penalties of delinquent loads on small out-of-order processors, with the ultimate goal to avoid processor stalls as much as possible. Our code transformation is applicable for general-purpose code, including unknown memory dependencies, complex control flow and pointers. We further propose a software-hardware co-design that combines the code transformation technique with lightweight hardware support to hide latencies on a stall-on-use in-order processor. / UPMARC