Efficient computation of the strain energy density for the assessment of fracture and fatigue of welded structures

Nowadays, the most widespread approach to fatigue design is based on S-N curves. Although this approach works in a lot of practical situations, there are also many others in which it does not give enough accurate results: The most important exception are probably the welded joints, which are widely adopted for the connection of\nstructural parts.\n\nIn recent years, many authors suggested to assess the fatigue life of welds on the basis of the local stress and strain fields in the most stressed zones, using the concepts of fracture mechanics. It was in this context that the SED criterion was formulated.\n\nThe purpose of this work is to investigate the numerical implementation of the SED criterion, and to further enhance its efficiency on the basis of some theoretical observations, as we are going to explain in details

Subgraph Epimorphisms: Theory and Application to Model Reductions in Systems Biology

This thesis develops a framework of graph morphisms and applies it to model reductionin systems biology. We are interested in the following problem: the collection of systemsbiology models is growing, but there is no formal relation between models in this collection.Thus, the task of organizing the existing models, essential for model refinement andcoupling, is left to the modeler. In mathematical biology, model reduction techniques havebeen studied for a long time, however these techniques are far too restrictive to be appliedon the scales required by systems biology.We propose a model reduction framework based solely on graphs, allowing to organizemodels in a partial order. Systems biology models will be represented by their reactiongraphs. To capture the process of reduction itself, we study a particular kind of graph morphisms:subgraph epimorphisms, which allow both vertex merging and deletion. We firstanalyze the partial order emerging from the merge/delete graph operations, then developtools to solve computational problems raised by this framework, and finally show both thecomputational feasibility of the approach and the accuracy of the reaction graphs/subgraphepimorphisms framework on a large repository of systems biology models.Cette th`ese d´eveloppe une m´ethode de morphismes de graphes et l’applique `a la r´eductionde mod`eles en biologie des syst`emes. Nous nous int´eressons au probl`eme suivant: l’ensembledes mod`eles en biologie des syst`emes est en expansion, mais aucune relation formelle entreles mod`eles de cet ensemble n’a ´et´e entreprise. Ainsi, la tˆache d’organisation des mod`elesexistants, qui est essentielle pour le raffinement et le couplage de mod`eles, doit ˆetre effectu´eepar le mod´elisateur. En biomath´ematiques, les techniques de r´eduction de mod`elesont ´etudi´ees depuis longtemps, mais ces techniques sont bien trop restrictives pour ˆetreappliqu´ees aux ´echelles requises en biologie des syst`emes.Nous proposons un cadre de r´eduction de mod`ele, bas´e uniquement sur des graphes, quipermet d’organiser les mod`eles en un ordre partiel. Les mod`eles de biologie des syst`emesseront repr´esent´es par leur graphe de r´eaction. Pour capturer le processus de r´eduction luimˆeme,nous ´etudierons un type particulier de morphismes de graphes: les ´epimorphismesde sous-graphe, qui permettent la fusion et l’effacement de sommets. Nous commenceronsen analysant l’ordre partiel qui ´emerge des op´erations de fusion et d’effacement, puis nousd´evelopperons des outils th´eoriques pour r´esoudre les probl`emes calculatoires de notrem´ethode, et pour finir nous montrerons la faisabilit´e de l’approche et la pr´ecision du cadre“graphes de r´eactions/´epimorphismes de sous-graphe”, en utilisant un d´epˆot de mod`elesde biologie des syst`emes

There is as yet Insufficient Data for a Meaningful Answer

International audienceFormal studies of discourse raise numerous interrogations on the nature and the definition of the way consecutive sentences combine with one another. The shift from discourse to dialogue brings forward even more specific issues. Dialogue acts are more intrinsically connected because of the dynamicity of the interaction. This article introduces a proof of concept of a formal compositional treatment of the relationship between consecutive utterances. Starting from neo-Davidsonian event semantics, we propose to use the relative response set as an intermediate set tool that allows us to define notions of question-answer correspondence, model the effect of clarification requests on previous utterances and compute semantic representations of dialogue interactions

Un Intergiciel de Gestion du Contexte basé Multi-Agent pour les Applications d'Intelligence Ambiante

The complexity and magnitude of Ambient Intelligence scenarios imply that attributes such as modeling expressiveness, flexibility of representation and deployment, as well as ease of configuration and development become central features for context management systems.However, existing works in the literature seem to explore these development-oriented attributes at a low degree.Our goal is to create a flexible and well configurable context management middleware, able to respond to different scenarios. To this end, our solution is built on the basis of principles and techniques of the Semantic Web and Multi-Agent Systems.We use the Semantic Web to provide a new context meta-model, allowing for an expressive and extensible modeling of content, meta-properties (e.g. temporal validity, quality parameters) and dependencies (e.g. integrity constraints).In addition, we develop a middleware architecture that relies on Multi-Agent Systems and a service component based design. Each agent of the system encapsulates a functional aspect of the context provisioning processes (acquisition, coordination, distribution, use).We introduce a new way to structure the deployment of agents depending on the multi-dimensionality aspects of the application's context model. Furthermore, we develop declarative policies governing the adaptation behavior of the agents managing the provisioning of context information.Simulations of an intelligent university scenario show that appropriate tooling built around our middleware can provide significant advantages in the engineering of context-aware applications.La complexité et l'ampleur des scénarios de l'Intelligence Ambiante impliquent que des attributs tels que l'expressivité de modelisation, la flexibilité de representation et de deploiement et la facilité de configuration et de developpement deviennent des caracteristiques centrales pour les systèmes de gestion de contexte. Cependant, les ouvrages existants semblent explorer ces attributs orientés-developpement a un faible degré.Notre objectif est de créer un intergiciel de gestion de contexte flexible et bien configurable, capable de répondre aux différents scenarios. A cette fin, notre solution est construite a base de techniques et principes du Web Semantique (WS) et des systèmes multi-agents (SMA).Nous utilisons le WS pour proposer un noveau meta-modèle de contexte, permettant une modelisation expressive et extensible du contenu, des meta-proprietés (e.g. validité temporelle, parametres de qualité) et des dépendances (e.g. les contraintes d'integrité) du contexte.De plus, une architecture a base de SMA et des composants logiciels, ou chaque agent encapsule un aspect fonctionnel du processus de gestion de contexte (acquisition, coordination, diffusion, utilisation) est developpée.Nous introduisons un nouveau moyen de structurer le deploiement d'agents selon les dimensions du modèle de contexte de l'application et nous elaborons des politiques déclaratives gouvernant le comportement d'adaptation du provisionnement contextuel des agents. Des simulations d'un scenario d'université intelligente montrent que un bon outillage construit autour de notre intergiciel peut apporter des avantages significatifs dans la génie des applications sensibles au contexte

Introduction to the finite element method

2019/202