This thesis concerns various aspects of the durability offibre optic sensors embedded in composite. Since repair orreplacement of embedded sensors is not generally possible, thefunctional reliability of embedded sensors is one of the mostimportant prerequisites for successful use. The main researchobjective was to investigate the interaction between the sensorand the composite, and how this is affecting the mechanical andoptical sensor response. Fibre optic sensors embedded incomposite structures induce local stress concentrations whenthe composite is subjected to mechanical loads andenvironmental changes such as temperature and moisture. Acomplex transfer of stresses through the interfaces between theembedded sensor and the composite occurs and can result inlarge local stresses in the composite and a significant changein the response of the embedded sensor. These stressconcentrations make the interfaces susceptible todebonding. The sensor performance was studied experimentally andnumerically. Some basic results were generated for the EFPI andBragg grating sensors. The phase-strain response was determinedduring static and fatigue loading. The results showed that thesensors were more reliable in compression than in tensilestatic and fatigue loading. Generally, the sensor reliabilityduring loading was significantly improved for the Bragg gratingsensors over that of the EFPI sensor, as an effect of thesensor geometry. This was also demonstrated in theinvestigations on impacts. Impacts do not necessarily result indamage in the composite, but might cause debonding or otherfailure modes in the sensor area. Large, local stressconcentrations occur at several positions in the EFPI sensor,which pointed out that this sensor type was not suitable forembedded applications. The shift in focus from the sensor concept based on the EFPIsensor to that based on the Bragg grating sensor manifesteditself in several studies. The calculated deformation fieldaround an embedded optical fibre was verified in experimentsusing a high-resolution moiré interferometric technique.Furthermore, the improvement in the coating technology wasverified. A significant higher interfacial strength wasobtained with the silane-treated glass surface. The resultsindicated that at least a twofold improvement of the shearstrength was obtained. To simultaneously measure the in-plane strain components andthe temperature change, embedded Bragg grating sensors werearranged in a rosette configuration. The relationship betweenthe optical response from each sensor and the strains in thelaminate was numerically and analytically established. Damage lead to stress redistribution in the sensor region,which may influence the output from the embedded Bragg gratingsensor. The effect was numerically evaluated for interfacialdamage, and was compared to that of a sensor with undamagedinterface. The results showed that debonding might have asignificant influence, in particular for combined thermal andmechanical loading. <b>Keywords</b>: composites, fibre optic sensor, embedded, EFPIsensor, Bragg grating sensor, durability, fatigue, impact,strain measurement, interface, stress analysis

Embedded computer systems have become ubiquitous. They are used in a wide spectrum of applications, ranging from household appliances and mobile devices to vehicle controllers and medical equipment. This dissertation deals with design and verification of embedded systems, with a special emphasis on the real-time facet of such systems, where the time at which the results of the computations are produced is as important as the logical values of these results. Within the class of real-time systems two categories, namely hard real-time systems and soft real-time systems, are distinguished and studied in this thesis. First, we propose modeling and verification techniques targeted towards hard real-time systems, where correctness, both logical and temporal, is of prime importance. A model of computation based on Petri nets is defined. The model can capture explicit timing information, allows tokens to carry data, and supports the concept of hierarchy. Also, an approach to the formal verification of systems represented in our modeling formalism is introduced, in which model checking is used to prove whether the system model satisfies its required properties expressed as temporal logic formulas. Several strategies for improving verification efficiency are presented and evaluated. Second, we present scheduling approaches for mixed hard/soft real-time systems. We study systems that have both hard and soft real-time tasks and for which the quality of results (in the form of utilities) depends on the completion time of soft tasks. Also, we study systems for which the quality of results (in the form of rewards) depends on the amount of computation allotted to tasks. We introduce quasi-static techniques, which are able to exploit at low cost the dynamic slack caused by variations in actual execution times, for maximizing utilities/rewards and for minimizing energy. Numerous experiments, based on synthetic benchmarks and realistic case studies, have been conducted in order to evaluate the proposed approaches. The experimental results show the merits and worthiness of the techniques introduced in this thesis and demonstrate that they are applicable on real-life examples.

To improve safety, reliability, and efficiency of automotive vehicles and other technical applications, embedded systems commonly use fault diagnosis consisting of fault detection and isolation. Since many systems are constructed as distributed embedded systems including multiple control units, it is necessary to perform global fault isolation using for example a central unit. However, the drawbacks with such a centralized method are the need of a powerful diagnostic unit and the sensitivity against disconnections of this unit. Two alternative methods to centralized fault isolation are presented in this thesis. The first method performs global fault isolation by a istributed sequential computation. For a set of studied systems, themethod gives, compared to a centralizedmethod, amean reduction inmaximumprocessor load on any unitwith 40 and 70%for systems consisting of four and eight units respectively. The second method instead extends the result of the local fault isolation performed in each unit such that the results are globally correct. By only considering the components affecting each specific unit, the extended result in each agent is kept small. For a studied automotive vehicle, the second method gives, compared to a centralized method, a mean reduction in the sizes of the results and the maximum processor load on any unit with 85 and 90% respectively. To perform fault diagnosis, diagnostic tests are commonly used. If the additional evaluation of tests can not improve the fault isolation of a component then the component is ready. Since the evaluation of a test comes with a cost in for example computational resources, it is valuable to minimize the number of tests that have to be evaluated before readiness is achieved for all components. A strategy is presented that decides in which order to evaluate tests such that readiness is achieved with as few evaluations of tests as possible. Besides knowing how fault diagnosis is performed, it is also interesting to assess the effect that fault diagnosis has on for example safety. Since fault tree analysis often is used to evaluate safety, this thesis contributes with a systematic method that includes the effect of fault diagnosis in fault trees. The safety enhancement due to the use of fault diagnosis can thereby be analyzed and quantified.

This thesis addresses the issues of data management in embedded systems' software. The complexity of developing and maintaining software has increased over the years due to increased availability of resources, e.g., more powerful CPUs and larger memories, as more functionality can be accommodated using these resources. In this thesis, it is proposed that part of the increasing complexity can be addressed by using a real-time database since data management is one constituent of software in embedded systems. This thesis investigates which functionality a real-time database should have in order to be suitable for embedded software that control an external environment. We use an engine control software as a case study of an embedded system. The findings are that a real-time database should have support for keeping data items up-todate, providing snapshots of values, i.e., the values are derived from the same system state, and overload handling. Algorithms are developed for each one of these functionalities and implemented in a real-time database for embedded systems. Performance evaluations are conducted using the database implementation. The evaluations show that the real-time performance is improved by utilizing the added functionality. Moreover, two algorithms for examining whether the system may become overloaded are also outlined; one algorithm for off-line use and the second algorithm for on-line use. Evaluations show the algorithms are accurate and fast and can be used for embedded systems.

The growing amount and diversity of functions to be implemented by the current and future embedded applications (like, for example, in automotive electronics) have shown that, in many cases, time-triggered and event-triggered functions have to coexist on the computing nodes and to interact over the communication infrastructure. When time-triggered and event-triggered activities have to share the same processing node, a natural way for the execution support can be provided through a hierarchical scheduler. Similarly, when such heterogeneous applications are mapped over a distributed architecture, the communication infrastructure should allow for message exchange in both time-triggered and event-triggered manner in order to ensure a straightforward interconnection of heterogeneous components. This thesis studies aspects related to the analysis and design optimisation for safety-critical hard real-time applications running on hierarchically scheduled distributed embedded systems. It first provides the basis for the timing analysis of the activities in such a system, by carefully taking into consideration all the interferences that appear at run-time between the processes executed according to different scheduling policies. Moreover, due to the distributed nature of the architecture, message delays are also taken into consideration during the timing analysis. Once the schedulability analysis has been provided, the entire system can be optimised by adjusting its configuration parameters. In our work, the entire optimisation process is directed by the results from the timing analysis, with the goal that in the end the timing constraints of the application are satisfied. The analysis and design methodology proposed in the first part of the thesis is applied next on the particular category of distributed systems that use FlexRay as a communication protocol. We start by providing a schedulability analysis for messages transmitted over a FlexRay bus, and then by proposing a bus access optimisation algorithm that aims at improving the timing properties of the entire system. For all the problems that we investigated, we have carried out extensive experiments in order to measure the efficiency of the proposed solutions. The results have confirmed both the importance of the addressed aspects during system-level design, and the applicability of our techniques for analysing and optimising the studied systems.

Embedded systems are becoming increasingly common in our everyday lives. As technology progresses, these systems become more and more complex. Designers handle this increasing complexity by reusing existing components. At the same time, the systems must fulfill strict functional and non-functional requirements. This thesis presents novel and efficient techniques for the verification of component-based embedded system designs. As a common basis, these techniques have been developed using a Petri net based modelling approach, called PRES+. Two complementary problems are addressed: component verification and integration verification. With component verification the providers verify their components so that they function correctly if given inputs conforming to the assumptions imposed by the components on their environment. Two techniques for component verification are proposed in the thesis. The first technique enables formal verification of SystemC designs by translating them into the PRES+ representation. The second technique involves a simulation based approach into which formal methods are injected to boost verification efficiency. Provided that each individual component is verified and is guaranteed to function correctly, the components are interconnected to form a complete system. What remains to be verified is the interface logic, also called glue logic, and the interaction between components. Each glue logic and interface cannot be verified in isolation. It must be put into the context in which it is supposed to work. An appropriate environment must thus be derived from the components to which the glue logic is connected. This environment must capture the essential properties of the whole system with respect to the properties being verified. In this way, both the glue logic and the interaction of components through the glue logic are verified. The thesis presents algorithms for automatically creating such environments as well as the underlying theoretical framework and a step-by-step roadmap on how to apply these algorithms.

This thesis addresses several issues related to the design and optimization of embedded systems. In particular, in the context of time-constrained embedded systems, the thesis investigates two problems: the minimization of the energy consumption and the implementation of predictable applications on multiprocessor system-on-chip platforms. Power consumption is one of the most limiting factors in electronic systems today. Two techniques that have been shown to reduce the power consumption effectively are dynamic voltage selection and adaptive body biasing. The reduction is achieved by dynamically adjusting the voltage and performance settings according to the application needs. Energy minimization is addressed using both offline and online optimization approaches. Offline, we solve optimally the combined supply voltage and body bias selection problem for multiprocessor systems with imposed time constraints, explicitly taking into account the transition overheads implied by changing voltage levels. The voltage selection technique is applied not only to processors, but also to buses with repeaters and fat wires. We investigate the continuous voltage selection as well as its discrete counterpart. While the above mentioned methods minimize the active energy, we propose an approach that combines voltage selection and processor shutdown in order to optimize the total energy. In order to take full advantage of slack that arises from variations in the execution time, it is important to recalculate the voltage and performance settings during run-time, i.e., online. However, voltage scaling is computationally expensive, and, thus, performed at runtime, significantly hampers the possible energy savings. To overcome the online complexity, we propose a quasi-static voltage scaling scheme, with a constant online time complexity O(1). This allows to increase the exploitable slack as well as to avoid the energy dissipated due to online recalculation of the voltage settings. Worst-case execution time (WCET) analysis and, in general, the predictability of real-time applications implemented on multiprocessor systems has been addressed only in very restrictive and particular contexts. One important aspect that makes the analysis difficult is the estimation of the system’s communication behavior. The traffic on the bus does not solely originate from data transfers due to data dependencies between tasks, but is also affected by memory transfers as result of cache misses. As opposed to the analysis performed for a single processor system, where the cache miss penalty is constant, in a multiprocessor system each cache miss has a variable penalty, depending on the bus contention. This affects the tasks’ WCET which, however, is needed in order to perform system scheduling. At the same time, the WCET depends on the system schedule due to the bus interference. In this context, we propose, an approach to worst-case execution time analysis and system scheduling for real-time applications implemented on multiprocessor SoC architectures.

Criticism concerning quality deficiencies and high production costs for housing has made many construction companies make efforts to improve performance, inspired by ideas from the manufacturing industry and in particular the car industry. This is often referred to as industrialised building. The ideas are not new but so far their spread has been limited. This study covers two years of one current effort to industrialise house building in a Swedish construction company, the Peab group. An investment in a new factory for automated production of concrete building elements had been made and start up of production in the factory took place during the time of the study. Two subunits, a contractor and a structural building element supplier were involved in the industrialisation effort and the study is confined to these. To improve performance, a prefabricated building system including Peab standards was to be developed and used across the organisation, instead of the existing local solutions. A project, Peab Gemensamt System concept (PGS), was established to conduct the task. The focus for the study is on the facilitators and barriers to make organisational changes for the purpose of industrialising house building in a construction company. Observations were made at meetings with the PGS core team and the involved Peab group staff was interviewed. Notions of organisational competence and embedded knowledge and action were applied to describe the studied company’s specific organisational context and to identify facilitators and barriers. Conclusions concern how organisational context, content of change and the change process interrelated and formed the outcome. In this case, fundamental ideas for change became local attempts. Establishing a project, PGS, for conducting change was new to the target organisation. Facilitators were not created to allow the organisation to learn to change in this new way. The PGS project could therefore not contribute directly to change. One building project introduced a prefabricated building system. It was beyond the team’s control to make necessary changes to benefit from it. Therefore, temporary adaptations to prevailing organisational conditions were made. Another building project introduced a new way of working during the detail design stage. It was within the team’s control to make necessary changes to benefit from it. Existing organisational competence could therefore be enhanced. The new factory had the potential to rationalise production of building elements, but it did not automatically solve problems related to the collaboration between the building element supplier and the contractor. Issues for improving performance through the studied ideas for industrialisation emerge from this. These concern combining the contractor’s and building element supplier’s different ways of working; meeting customer requirements while realising certain industrialisation ideas; and the roles of the permanent and temporary organisations for embedding knowledge without losing flexibility. / QC 20100924

Författare: Magnus Gustafsson Niclas Hagel Handledare: Thomas Knoll Examinator: Martin Danielsson Titel: Al-Jazeera och CNN - En jämförande fallstudie i krigsjournalistik Typ av rapport: C - uppsats Ämne: Medie- och Kommunikationsvetenskap År: Höstterminen 2008 Sektion: Sektionen för Hälsa och Samhälle Syfte: Vårt syfte är att studera och jämföra al-Jazeeras och CNN:s bevakning av en händelse i Afghanistankonflikten för att kunna redogöra för eventuella skillnader. Vi vill se hur olika faktorer påverkar journalistiken. En analys ur ett genusperspektiv kommer också att göras. Metod: Fallstudie har tillämpats som huvudsaklig metod och vid analys av material har innehållsanalys och kritisk diskursanalys använts. Slutsatser: Efter att ha jämfört de två nyhetskanalerna kan vi tydligt se att det finns stora skillnader i rapporteringen av ett amerikanskt flyganfall mot en afghansk by. CNN som amerikansk nyhetskanal visar att deras rapportering påverkas av det amerikanska medieklimatet där en neutral krigsrapportering kan ses som stötande och journalister ständigt utsätts för påtryckningar. Ur ett genusperspektiv ser vi dock tydliga likheter mellan kanalerna.

Les Syst emes sur puce (soc) sont de plus en plus complexes. Leur concep- tion repose largement sur la r eutilisation des blocs, appel es ip (Intellectual Pro- perty). Ces ip sont construites par des concepteurs di erents travaillant avec des outils di erents. Aussi existe-t-il une demande pressante concernant l'in- terop erabilit e des ip, c'est- a-dire d'assurer la compatibilit e des formats et l'uni- cit e d'interpr etation de leurs descriptions. ip-xact constitue un standard de facto d e ni dans le cadre de la conception de syst emes electroniques pour fournir des repr esentations portables de composants ( electroniques) et d'ip. ip-xact a r eussi a assurer la compatibilit e syntaxique, mais il a n eglig e les aspects comportemen- taux. uml est un langage de mod elisation classique pour le g enie logiciel. Il four- nit des el ements de mod ele propres a couvrir tous les aspects structurels et com- portementaux d'une conception. Nous pr^onons une utilisation conjointe d'uml et d'ip-xact pour r ealiser la n ecessaire interop erabilit e. Plus pr ecis ement, nous r eutilisons le pro l uml pour marte pour etendre uml avec des caract eristiques temps r eel embarqu ees. Le paquetage Mod elisation G en erique de Ressources de marte est etendu pour prendre en compte des sp eci cit es structurelles d'ip- xact. Le Mod ele de temps de marte etend le mod ele atemporel d'uml avec le concept de temps logique bien adapt e a la mod elisation au niveau syst eme electronique. La premi ere contribution de cette th ese est la d e nition d'un mod ele de do- maine pour ip-xact. Ce mod ele de domaine est utilis e pour construire un pro l uml pour ip-xact qui r eutilise autant que possible les st er eotypes de marte et en d e nit de nouveaux uniquement en cas de besoin. Une transformation de mod ele a et e mise en uvre dans ATL permettant d'utiliser des editeurs graphiques uml comme front-end pour la sp eci cation d'ip et la g en eration des sp eci cations ip- xact correspondantes. Inversement, des chiers ip-xact peuvent ^etre import es dans un outil uml par une autre transformation de mod eles. La deuxi eme contribution porte sur la mod elisation de propri et es et de con- traintes temporelles portant sur des ip. Les diagrammes comportementaux d'uml sont enrichis avec des horloges logiques et des contraintes d'horloge exprim ees dans le langage de speci cation de contraintes d'horloge (ccsl) de marte. La sp eci cation ccsl peut alors servir de mod ele de r ef erence pour le com- portement temporel attendu et la v eri cation des impl ementations a di erents niveaux d'abstraction (rtl ou tlm). Les propri et es temporelles sont v eri ees en utilisant une biblioth eque sp ecialis ee d'observateurs.