De cette thèse, une nouvelle méthode éléments finis hybride MAX-FEM dédiée à la modélisation thermomécanique des structures avec couches minces a été développée. Cette nouvelle approche se base sur un couplage analytique-numérique de deux méthodes : les Développements Asymptotiques Raccordés (MAE) et la Partition de l'Unité (PUM). Ce couplage consiste à construire l'enrichissement de la PUM par MAE est mène à une forme corrigée de la méthode des éléments finis classique (FEM). Cette correction est obtenue à travers des matrices de correction contenant les informations géométriques et caractéristiques du matériau de la couche mince. Les matrices introduites par l'approche MAX-FEM simplifient son implémentation numérique sous différents codes de calculs (MATLAB, ABAQUS, ...) et permettent l'obtention de la solution globale en un seul calcul. Les résultats obtenus par la MAX-FEM pour des applications 1D et 2D thermomécaniques montrent une très bonne précision avec un temps de calcul minimal et sans raffinement de maillage. De plus, la MAX-FEM surmonte les limitations de la MAE ainsi que celle de la PUM en termes de nombre de calculs, de la sensibilité aux propriétés des matériaux, des conditions aux limites ainsi que l'intégration numérique. Finalement, l'approche MAX-FEM est exploitée pour le développement d'un nouveau protocole expérimental dédié à la caractérisation thermique des couches minces. Ce protocole vise l'identification, de manière simple, de la conductivité thermique de la couche mince après son élaboration et sous les deux régimes transitoire et permanent. L'approche consiste à confronter la nature du transfert thermique d'une éprouvette homogène à une contenant une couche mince. La différence relevée est directement liée à la conductivité thermique de la couche mince. Les résultats obtenus, après réalisation du banc d'essais, montrent une bonne précision de l'approche avec une méthodologie de mesure simple à mettre en oeuvre / This work introduces a new simplified finite elements method MAX-FEM based on hybrid analytical-numerical coupling. This method is intended to the multi-scales analysis of transient thermomechanical behavior of mediums containing thin layers such as bounded and coated structures. The MAX-FEM consists in correcting the classical Finite Elements Method (FEM) by correction matrices taking into account the presence of thin layers without any mesh refinement. The proposed correction is based on the analytical approach of Matched Asymptotic Expansions (MAE) and the numerical method of Partition of Unity Method (PUM). The developed approach can easily implemented under different numerical codes (MATLAB, ABAQUS, ...) and can be used to perform mechanical, thermal and thermomechanical analyses of 1D and 2D bounded and coated structures. The obtained results show a good accuracy with short computation time, and without any required mesh refinement. Also, the developed method overcomes the limitation of the MAE and PUM methods by exploiting the advantages of their coupling. Finally, the MAX-FEM approach was also used to develop an experimental test bench intended to the thermal characterization of thin layers. Indeed, a simple confrontation between the heat transfer in an homogeneous structure and a second structure with thin layer allows identifying the thermal conductivity in both transient and stationary regimes. The test bench is simple to release and the obtained results for brazed structure show a good accuracy of the developed approach.

<p>There are several standards for wireless communication. People that are involved in computers and networking recognize names like Bluetooth, HiperLAN and IEEE 802.11. The last one was standardized in 1997 [2,6]and has begun to reach acceptance as a solid ground for wireless networking. A fundamental part of an IEEE 802.11 node is the Medium Access Controller, or MAC. It establishes and controls communication with other nodes, using a physical layer unit. </p><p>The work has been carried out as final project at Linkopings Universitet, it has been about the improvement of the functions of MAC layer. I have developed some of the required functions that PUM uses to interact with the MAC layer. Because of that, I have implemented the Reception functions of MAC layer, having the possibility of using short control frames RTS/CTS to minimize collision.</p>

There are several standards for wireless communication. People that are involved in computers and networking recognize names like Bluetooth, HiperLAN and IEEE 802.11. The last one was standardized in 1997 [2,6]and has begun to reach acceptance as a solid ground for wireless networking. A fundamental part of an IEEE 802.11 node is the Medium Access Controller, or MAC. It establishes and controls communication with other nodes, using a physical layer unit. The work has been carried out as final project at Linkopings Universitet, it has been about the improvement of the functions of MAC layer. I have developed some of the required functions that PUM uses to interact with the MAC layer. Because of that, I have implemented the Reception functions of MAC layer, having the possibility of using short control frames RTS/CTS to minimize collision.