A French composer in the light of his correspondence : Henri Tomasi (1901-1971)

La présente thèse s’appuie sur les correspondances adressées par le compositeur Henri Tomasi, entre 1916 et 1940, à Joséphine et Xavier Tomasi, ses parents, puis de 1954 à 1971, à Jean Molinetti, son ami le plus proche. Il s’agit d’un ensemble de 533 lettres inédites, qui ont été transcrites, classées, et annotées. Cet unique témoignage écrit du musicien nous permet de comprendre les répercussions qu’eurent sur son œuvre créatrice les événements qui ponctuèrent sa vie et dont ses courriers se font l’écho. Nous étudions ainsi tour à tour l’environnement familial d’Henri Tomasi, au travers notamment du rôle fondamental que joua son père tant dans son éducation que dans le cadre de ses recherches sur la musique traditionnelle corse ; nous voyons la façon dont le jeune musicien conduisit ses études musicales, les rapports qu’il entretint avec les institutions de son temps, mais aussi le rôle que purent jouer les différentes activités de chef d’orchestre qu’il exerça à certaines périodes de son existence. Nous assistons également à l’évolution progressive de sa pensée et à sa transposition dans son œuvre musicale. Tout au long de ces années, cette correspondance au cours de laquelle le musicien passe successivement d’une écriture contrainte à une écriture choisie, nous livre des informations capitales et nous séduit par la vivacité de son ton et le mordant de son style.The present thesis is based on all the written correspondence from the composer Henri Tomasi to Joséphine and Xavier Tomasi, his parents, between 1916 and 1940.Then, from 1954 to 1971 to Jean Molinetti, his closest friend. This correspondence includes 533 unpublished letters which have been transcribed, classified and annotated. This musician's unique written testimony allows us to understand how the events which punctuated his life, echoed in his letters, had repercussions on his creative work. Thus in turn, we will study Henri Tomasi's family environment considering notably the fundamental role played by his father in his education as well as in the field of his research on traditional Corsican music ; we'll see the way the young musician conducted his musical studies, his relationship with the institutions of his time but also the role his various activities as a conductor were to play at certain periods of his life. We will also follow the progressive evolution of his thought and its transposition in his musical work. In this correspondence, throughout all those years, the musician's constrained writing style gradually evolved into a more personal one. It gives us essential information and Tomasi seduces us by the incisiveness of his style and by the liveliness of his tone

Kriging metamodels-based multi-objective shape optimization applied to a multi-scale heat exchanger

International audienceHeat exchanger behaviour is a multi-scale issue where local scale enhancement mechanisms coexist with global scale distribution ones. The present work investigates a multi-objective shape optimization of a heat exchanger. The proposed method is sufficiently robust to address multi-scale issues and allows industrial applications. Heat exchanger performances are evaluated using computational fluid dynamics (CFD) simulations. A genetic algorithm coupled with a Kriging-based metamodelling are used as optimization tools. Clustering and Self-Organizing Maps (SOM) are used to analyse the optimization results. A metamodel builds an approximation of a simulator response (CFD) whose evaluation cost is reduced to be used together with genetic algorithm. An adaptive sampling is used to build cheap and precise approximations. The present optimization method is applied to a plate heat exchanger which constitutes a representative example of the aforementioned multi-scale aspects. The results show that the metamodelling is a paramount element of the method, ensuring the robustness and the versatility of the optimisation process. Additionally, it allows to build correlations of the local scale used to determine the global performances of the heat exchanger. The clustering and the SOM highlight a finite number of shapes, which represent a compromise among the antagonist objective functions, tailoring the method to an industrial context

Nanolayered Hard Coatings for Mechanical Applications

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Aluminum-Based Nanostructured Coatings Deposited by Magnetron Sputtering for Corrosion Protection of Steels

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MATÉRIAU MULTICOUCHE RÉSISTANT A L'OXYDATION EN MILIEU NUCLÉAIRE

The invention relates to a multilayer material including a zirconium substrate that is coated with a multilayer coating, the multilayer coating including metal layers consisting of identical or different materials selected from among chromium, a chromium alloy, and a ternary alloy of the Nb-Cr-Ti system. Such a material has improved resistance to oxidation in accident conditions of a nuclear reactor. The invention further relates to a multilayer coating, to a part entirely or partially consisting of the multilayer material or of the multilayer coating, as well as to the method for producing the multilayer material, e.g. a magnetron sputtering method.Matériau multicouche comprenant un substrat à base de zirconium recouvert d'un revêtement multicouche, le revêtement multicouche comprenant des couches métalliques composées dematières identiques ou différentes choisies parmi le chrome, un alliage de chromeouun alliage ternaire du système Nb-Cr-Ti. Un tel matériau présente une résistance à l'oxydation améliorée en conditions accidentelles d'un réacteur nucléaire. L'invention concerne également un revêtement multicouche,une pièce composée en tout ou partie du matériau multicouche ou du revêtementmulticouche, ainsi que le procédé de fabrication du matériau multicouchetel que par exemple un procédé de pulvérisation cathodique magnétron

On the use of Schur complement to improve the efficiency of RBF-based mesh deformation applied to internal cooling

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RBF-based mesh morphing improvement using Schur complement applied to rib shape optimization

International audiencePurpose This paper aims to improve the radial basis fuction mesh morphing method. During a shape optimization based on computational fluid dynamic (CFD) solvers, the mesh has to be changed. Two possible strategies are re-meshing or morphing. The morphing one is advantageous because it preserves the mesh connectivity, but it must be constrained. Design/methodology/approach RBF mesh deformation is one of the most robust and accurate morphing method. Using a greedy algorithm, the computational cost of the method is reduced. To evaluate the morphing performances, a rib shape optimization is performed using the NSGA-II algorithm coupled to kriging metamodels based on CFD. The morphing method is then compared to a re-meshing strategy. Findings The authors propose a method, based on Schur complement, to speed-up the greedy process. By using the information of the previous iteration, smaller linear systems are solved and time is saved. The optimization results highlight the interest of using a morphing-based metamodel regarding the resolution time and the accuracy of the interpolated solutions. Originality/value A new method based on Schur complement is addressed to speed-up the greedy algorithm and successfully applied to a shape optimization

Études de l'influence du solveur CFD sur les résultats de l'optimisation de forme d'un échangeur

National audienceLe choix du solveur CFD influence les résultats des simulations réalisées mais peut également impacter les résultats d’un processus d’optimisation. Cette étude compare le comportement des solveurs Code_Saturne et ANSYS Fluent dans le cadre d’une optimisation de la forme d’une ailette trapézoïdale. Les résultats mettent en évidence un écart maximum de 5% entre les évaluations des deux solveurs. Toutefois, les individus optimaux différent. Cela semble principalement causé par une réponse différente des solveurs dans une région de l’espace des paramètres. Celle-ci modifie la courbure de la surface de réponse et déplace ainsi le bassin d’attraction des formes optimales