Dans les années 90, la commission européenne a sollicité la mise au point d’un système de contrôle commande et de signalisation ferroviaire commun à tous les réseaux des états membres : le système ERTMS « European Railway Traffic Management System ». Il s’agit d’un système réparti complexe dont le déploiement complet est long et coûteux. L’objectif global consiste à diminuer les coûts de validation et de certification liés à la mise en œuvre de ce nouveau système en Europe. La problématique scientifique réside dans la modélisation formelle de la spécification afin de permettre la génération automatique des scénarios de test. Les verrous scientifiques, traités dans cette thèse, sont liés d’une part à la transformation de modèle semi-formel en modèle formel en préservant les propriétés structurelles et fonctionnelles des constituants réactifs du système réparti, et d’autre part à la couverture des tests générés automatiquement. Les constituants sont sous la forme de boîte noire. L’objectif consiste à tester ces derniers à travers la spécification ERTMS. Nous avons développé une approche de modélisation basée sur le couplage de modèles semi-formels (UML) et de modèles formels (Réseaux de Petri). Ce couplage se fait à travers une technique de transformation de modèles. Nous avons développé ensuite une méthode de génération automatique de scénarios de test de conformité à partir des modèles en réseaux de Petri. Les scénarios de test ont été considérés comme une séquence de franchissement filtrée puis réduite du réseau de Petri interprété représentant la spécification. Ces scénarios ont été exécutés sur notre plateforme de simulation ERTMS / European Union set up a European rail traffic management system “ERTMS” to ensure, with high level of safety, train operation on different European networks. As the full deployment of this system is long and expensive, evolutions are necessary and raise other technological challenges. The goal is to determine how to use ERTMS specifications to produce test scenarios. This work presents methods, models and tools dedicated to the generation of test scenarios for the validation of ERTMS components based on functional requirements. The development of ERTMS system requires adequate methods for Modelling and evaluating its behavior. Evaluation and certification of the system can be done by generating test scenarios applying formal methods. The Unified Modelling Language (UML) is a widely accepted Modelling standard in industry. However, it is a semi-formal language and it does not allow verification of system behavior. In this case, formal models like Petri Net can be used. These methods are used in order to formalize ERTMS specification. Tests scenarios are generated on the basis of Petri net models. One scenario is considered like a firing sequence in the reachability graph of the Petri net. Then, test scenarios are applied on ERTMS platform simulator in order to check the components and to give test verdicts. Finally, the approach, developed in this document, has been applied to ERTMS components in order to demonstrate the validation and certification costs reduction and also to minimize the upgrade and retrofit constraints and validation cost

abstract: The South African Middle Stone Age (MSA), spanning the Middle to Late Pleistocene (Marine Isotope Stages (MIS) 8-3) witnessed major climatic and environmental change and dramatic change in forager technological organization including lithic raw material selection. Homo sapiens emerged during the MSA and had to make decisions about how to organize technology to cope with environmental stressors, including lithic raw material selection, which can effect tool production and application, and mobility. This project studied the role and importance of lithic raw materials in the technological organization of foragers by focusing on why lithic raw material selection sometimes changed when the behavioral and environmental context changed. The study used the Pinnacle Point (PP) MSA record (MIS6-3) in the Mossel Bay region, South Africa as the test case. In this region, quartzite and silcrete with dramatically different properties were the two most frequently exploited raw materials, and their relative abundances change significantly through time. Several explanations intertwined with major research questions over the origins of modern humans have been proposed for this change. Two alternative lithic raw material procurement models were considered. The first, a computational model termed the Opportunistic Acquisition Model, posits that archaeological lithic raw material frequencies are due to opportunistic encounters during random walk. The second, an analytical model termed the Active-Choice Model drawn from the principles of Optimal Foraging Theory, posits that given a choice, individuals will choose the most cost effective means of producing durable cutting tools in their environment and will strategically select those raw materials. An evaluation of the competing models found that lithic raw material selection was a strategic behavior in the PP record. In MIS6 and MIS5, the selection of quartzite was driven by travel and search cost, while during the MIS4, the joint selection of quartzite and silcrete was facilitated by a mobility strategy that focused on longer or more frequent stays at PP coupled with place provisioning. Further, the result suggests that specific raw materials and technology were relied on to obtain food resources and perform processing tasks suggesting knowledge about raw material properties and suitability for tasks. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2017

Role-based modeling has been investigated for over 35 years as a promising paradigm to model complex, dynamic systems. Although current software systems are characterized by increasing complexity and context-dependence, all this research had almost no influence on current software development practice, still being discussed in recent literature. One reason for this is the lack of a coherent, comprehensive, readily applicable notion of roles. Researchers focused either on relational roles or context-dependent roles rather then combining both natures. Currently, there is no role-based modeling language sufficiently incorporating both the relational and context-dependent nature of roles together with the various proposed constraints. Hence, this paper formalizes a full-fledged role-based modeling language supporting both natures. To show its sufficiency and adequacy, a real world example is employed.

Since the year 1977, role modeling has been continuously investigated as promising paradigm to model complex, dynamic systems. However, this research had almost no influence on the design of todays increasingly complex and context-sensitive software systems. The reason for that is twofold. First, most modeling languages focused either on the behavioral, relational or context-dependent nature of roles rather than combining them. Second, there is a lack of tool support for the design, validation, and generation of role-based software systems. In particular, there exists no graphical role modeling editor supporting the three natures as well as the various proposed constraints. To overcome this deficiency, we introduce the Full-fledged Role Modeling Editor (FRaMED), a graphical modeling editor embracing all natures of roles and modeling constraints featuring generators for a formal representation and source code of a rolebased programming language. To show its applicability for the development of role-based software systems, an example from the banking domain is employed.

L'élasticité est une propriété qui permet aux systèmes Cloud de s'auto-adapter à leur charge de travail en provisionnant et en libérant des ressources informatiques, de manière autonomique, lorsque la demande augmente et diminue. En raison de la nature imprévisible de la charge de travail et des nombreux facteurs déterminant l'élasticité, fournir des plans d'action précis pour gérer l'élasticité d'un système cloud, tout en respectant des politiques de haut niveau (performances, cout, etc.) est une tâche particulièrement difficile.Les travaux de cette thèse visent à proposer, en utilisant le formalisme des bigraphes comme modèle formel, une spécification et une implémentation des systèmes Cloud Computing élastiques sur deux aspects : structurel et comportemental.Du point de vue structurel, le but est de définir et de modéliser une structure correcte des systèmes Cloud du côté " backend ". Cette partie est supportée par les capacités de spécification fournies par le formalisme des Bigraphes, à savoir : le principe de "sorting" et de règles de construction permettant de définir les desiderata du concepteur. Concernant l'aspect comportemental, il s'agit de modéliser, valider et implémenter des stratégies génériques de mise à l'échelle automatique en vue de décrire les différents mécanismes d'auto-adaptation élastiques des systèmes cloud (mise à l'échelle horizontale, verticale, migration, etc.), en multi-couches (i.e., aux niveaux service et infrastructure). Ces tâches sont prises en charge par les aspects dynamiques propres aux Systèmes Réactifs Bigraphiques (BRS) notamment par le biais des règles de réaction.Les stratégies d'élasticité introduites visent à guider le déclenchement conditionnel des différentes règles de réaction définies, afin de décrire les comportements d'auto-adaptation des systèmes Cloud au niveau service et infrastructure. L'encodage de ces spécifications et leurs implémentations sont définis en logique de réécriture via le langage Maude. Leur bon fonctionnement est vérifié formellement à travers une technique de model-checking supportée par la logique temporelle linéaire LTL.Afin de valider ces contributions d'un point de vue quantitatif, nous proposons une approche à base de file d'attente pour analyser, évaluer et discuter les stratégies d'élasticité d'un système Cloud à travers différents scénarios simulés. Dans nos travaux, nous explorons la définition d'une "bonne" stratégie en prenant en compte une étude de cas qui repose sur la nature changeante de la charge de travail. Nous proposons une manière originale de composer plusieurs stratégies d'élasticité à plusieurs niveaux afin de garantir différentes politiques de haut-niveau. / Elasticity property allows Cloud systems to adapt to their incoming workload by provisioning and de-provisioning computing resources in an autonomic manner, as the demand rises and drops. Due to the unpredictable nature of the workload and the numerous factors that impact elasticity, providing accurate action plans to insure a Cloud system's elasticity while preserving high level policies (performance, costs, etc.) is a particularly challenging task. This thesis aims at providing a thorough specification and implementation of Cloud systems, by relying on bigraphs as a formal model, over two aspects: structural and behavioral.Structurally, the goal is to define a correct modeling of Cloud systems' "back-end" structure. This part is supported by the specification capabilities of Bigraph formalism. Specifically, via "sorting" mechanisms and construction rules that allow defining the designer's desiderata. As for the behavioral part, it consists of model, implement and validate generic elasticity strategies in order to describe Cloud systems' auto-adaptive behaviors (i.e., horizontal and vertical scaling, migration, etc.) in a cross-layer manner (i.e., at service and infrastructure levels). These tasks are supported by the dynamic aspects of Bigraphical Reactive Systems (BRS) formalism (through reaction rules).The introduced elasticity strategies aim at guiding the conditional triggering of the defined reaction rules, to describe Cloud systems' auto-scaling behaviors in a cross-layered manner. The encoding of these specifications and their implementation are defined in Rewrite Logic via Maude language. Their correctness is formally verified through a model-checking technique supported by the linear temporal logic LTL.In order to quantitatively validate these contributions, we propose a queuing-based approach in order to evaluate, analyze and discuss elasticity strategies in Cloud systems through different simulated execution scenarios. In this work, we explore the definition of a “good” strategy through a case study which considers the changing nature of the input workload. We propose an original way de compose different cross-layer elasticity strategies to guarantee different high-level policies.

As technological advancements and manufacturing techniques continues to bring us more complex and powerful hardware, software engineers struggle to keep up with this rapid progress and reap the benefits brought by this hardware. In the field of safety-critical system development, where a thorough understanding and deterministic nature of the hardware often is required, the cost of development closely relates to the complexity of the hardware used. For software developers to be able to reap the benefits of the technological advancement in hardware design, a Correct-by-Construction with a model- based design flow seem promising. Even though there seem to be significant benefits in using a Correct-by-Construction workflow for developing safety- critical systems, it is far from exclusively used within the industry. Therefore, this thesis illustrates how a model-based design flow should be applied when developing safety-critical systems for usage in the rail transport sector. This thesis also explores the benefits Correct-by-Construction can bring to the development process of safety-critical systems. Within this thesis, two different modeling tools, ForSyDe and Simulink, were used to achieve a model-based design flow. The functionality of these tools is investigated to see how they can be used for developing safety-critical systems, meeting the EN 50128 standard. The result presented is an example of how these tools can be used within a model-based design flow which meets the EN 50128 standard for developing Safety Integrity Level (SIL) 4 systems. The thesis also compares the tools investigated and highlights their differences. Finally, future work required to create a complete Correct-by-Construction workflow that complies with the EN 50128 standard requirements for system development is identified. / Allt eftersom teknologiska framsteg och tillverkningstekniker fortsätter att ge oss tillgång till mer komplex och kraftfull hårdvara så kämpar mjukvaruingenjörer fibrilit med att kunna hänga med i denna utvecklingstakt och kunna utnyttja de nya möjligheterna som denna nya hårdvara ger. Inom fältet för säkerhetskritiska system, där en genomgående förståelse av och deterministiska egenskaper för hårdvara ofta krävs, så är kostnaden för utveckling nära relaterat till komplexiteten för hårdvaran som används. För att kunna ta till vara på de fördelar som dessa nya teknologiska framsteg för med sig så föreslås ofta användningen av utvecklingsprocessen Korrektvid- Konstruktion. Även fast det verkar finnas stora fördelar med att använda Korrekt-vid-Konstruktion som utvecklingsprocess så har det inte sett en bred användning inom industrin. På grund av detta så försöker denna avhandling svara på hur ett modelleringsbaserat utvecklingsflöde kan användas vid utveckling av säkerhetskritiska system för tågtransportsektorn. Arbetet undersöker även fördelarna med användningen av Korrekt-vid-Konstruktion vid utveckling av säkerhetskritiska system. Arbetet i denna avhandling undersöker hur två olika modeleringsverktyg, ForSyDe och Simulink, kan användas i ett modeleringsbasert utvecklingsflöde. Funktionaliteten för dessa modeleringsverktyg undersöks för att se hur dem kan användas för utveckling av säkerhetskritiska system på ett sätt som klarar av kraven i EN 50128 standarden. Resultaten som presenteras är ett exempel på hur dessa verktyg kan användas i ett modeleringsbaserat utvecklingsflöde som möter kraven i EN 50128 standarden för utveckling av SIL 4 system. Arbetet jämför även de undersökta modeleringsverktygen för att påvisa deras skillnader. Till sist så beskrivs det framtida arbete som krävs för att få till en komplett utvecklingsprocess som är Korrekt-vid-Konstruktion och även möter systemutvecklingskraven i EN 50128 standarden.

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