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Le multipactor est un phénomène parasite qui se produit dans les dispositifs où l'on transmet une onde hyperfréquence sous vide tels que les tubes électroniques à vide, les cavités résonnantes pour accélérateurs de particules et les circuits micro-ondes à bord des satellites. Il consiste en une avalanche d'électrons mis en mouvement par un champ hyperfréquence. La simulation du multipactor est cruciale dans tout design de structure HF sous vide. Les géométries complexes 3D d'objets imposent de posséder des outils de simulations tridimensionnels pour prédire ce phénomène. Le premier travail de cette thèse a consisté à valider un logiciel de simulation 3D du multipactor, Musicc3D, à la fois par le calcul et l'expérimentation. Une étude théorique à une dimension ainsi qu'une simulation 2D éprouvée ont été réalisées et les résultats du logiciel Musicc3D ont été favorablement confrontés à leurs résultats. Des règles de définition du maillage 3D ont été établies pour un bon fonctionnement de la simulation 3D. Toujours pour valider la simulation, l'ensemble des cavités accélératrices construites par l'IPNO ces dernières années a été simulé et favorablement comparé aux observations de barrières de multipactor quand elles existaient. Dans le but d'exploiter les prédictions de la simulation 3D, mais aussi de la valider et enfin d'être capable de qualifier différents matériaux et/ou états de surfaces, une cavité résonnante équipée de mesures dédiées au multipactor a été construite. Les premiers résultats obtenus avec cette cavité ont été favorablement comparés à la simulation. / Multipacting is a parasitic phenomenon and extremely detrimental in devices where there is a ultra high frequency wave transmitted in a vacuum environment such as vacuum electron tubes, resonant cavities for particle accelerators and microwave circuits on board of satellites. It consists of an avalanche of electrons put in motion by a microwave field. Multipacting simulation is crucial in any HF structure design. The complex 3D geometrics obligates to have three-dimensional simulation tools to predict this phenomenon. The first study in this thesis consisted in validating a 3D simulation software of Multipacting, Musicc3D, by calculation and experimentation. A theoretical study with one dimension and a a tested 2D simulation were carried out and the results of the software Musicc3D were favorably confronted to their results. 3D grid definition rules were established for the proper working of the 3D simulation. Also to validate the simulation, the whole of the park of accelerating cavities built by the IPNO these last years was simulated and favorably compared with the observations of barriers of Multipacting when they existed. With an aim of exploiting the predictions of the 3D simulation, but also to validate it and finally be able to qualify various materials and/or state of surfaces, a resonant cavity equipped with measurements dedicated for Multipacting was built. The first results obtained with this cavity were favorably compared to the simulation.

Dans l’optique de la conception et du développement d’un siège aéronautique et afin derespecter la règlementation sécuritaire en vigueur, la structure du siège développé doitpermettre une dissipation rapide de l’énergie perçue en cas de crash aérien (Fig. 1), ceci dansle but de protéger les passagers. La majorité des systèmes intégrés à la structure des sièges etpermettant cette absorption d’énergie (Fig. 2) est constituée de composants métalliques qui sedéforment plastiquement pour dissiper l’énergie due au crash. Actuellement, l’industrie et larecherche se tournent vers les matériaux composites pour substituer de tels systèmes.Cependant le comportement de ces matériaux lors de sollicitations mécaniques sévères estfortement différent des matériaux métalliques, notamment dû au fait que les mécanismesd’endommagement sont très distincts.Le but de cette étude portant sur des structures tubulaires composites est d’évaluer leurcapacité à dissiper l’énergie. A cette fin, différentes stratifications ont été testées encompression (Fig. 3 et 4) dans le but de déterminer leur comportement, comparer leurspropriétés et calculer leurs valeurs de SEA (absorption d'énergie spécifique, en kJ.kg-1)servant à évaluer leur aptitude à dissiper l’énergie engendrée en cas de crash. Ces dernièressont issues des courbes effort-déplacement obtenues lors des essais d’écrasement (Fig. 5). Lesdifférents essais de compression ont été instrumentés et suivis au moyen de caméras rapides etdes images post-essais ont été réalisées par tomographie pour comprendre les mécanismesd’endommagement mis en jeu (Fig. 4 et 6). Ces essais ont été réalisés à vitesse de chargementquasi-statique puis dynamique et selon diverses conditions limites. Les différents résultats decomportement en compression sont également utilisés dans le but de construire et enrichir unmodèle de calcul par éléments finis (Fig. 7 et 8) permettant de simuler la réponse de structurescomposites de différentes natures soumises au crash en intégrant la géométrie et lacomposition de la structure (Fig. 8).L’objectif de ce travail de recherche est ainsi d’évaluer l’énergie pouvant être dissipée par desstructures tubulaires composites, de comparer les absorptions induites par des structurescomposites de compositions différentes, et/ou bi-matériaux, et enfin de fournir un modèleéléments finis représentant le comportement de structures composites en compression jusqu’àl’endommagement et la ruine de la structure.Il a ainsi été établi qu’en chargement statique, un stratifié unidirectionnel orienté à 0° etstabilisé par des plis de tissus répond fortement aux attentes en terme de dissipation d’énergie,mais pas en sollicitation dynamique. Dans ce cas, une stratification à 90° semble plusadéquate. D’autre part, un confinement forcé vers l’intérieur est avantageux dans la plupartdes cas, réduisant le pic d’effort initial sans diminuer drastiquement la valeur de SEA. / With the perspective of the design and development of an aircraft seat and in order to respectthe safety regulations in effect, the structure of the developed seat must allow for a swiftdissipation of the energy received in the event of an aircraft crash (Fig. 1) so as to protect thepassengers. The majority of systems integrated into the seats structure and allowing energydissipation (Fig. 2) consists of metal components that sustain plastic deformation to dissipatethe energy induced by the crash. Currently, industry and research sectors are turning theirfocus towards composite materials to substitute such systems. However, the behavior of thesematerials during severe mechanical stress is strongly different from metallic materials, inparticular due to the fact that damage mechanisms are very distinct.The purpose of this study on composite tubular structures is to evaluate their ability todissipate the energy. To this end, different laminate structures were tested in compression(Fig. 3 and 4) in order to identify their behavior, compare their properties and calculate theirSEA value (Specific Energy Absorption, in kJ.kg-1) used to evaluate their capacity to dissipatethe energy generated during a crash. Those are resulting from the load-displacement curvesobtained during the crushing tests (Fig. 5). The various compression tests were instrumentedand monitored by means of rapid imaging cameras and post-crushing tomographic imaginghas been realized in order to understand the damage mechanisms involved (Fig. 4 and 6).Testing has been carried out under quasi-static and dynamic loading and using severalboundary conditions. The different results of compression and crushing behavior are also usedin order to build and improve a finite element calculation model (Fig. 7 and 8) allowing tosimulate the response of composite structures of different natures subjected to crash byintegrating the geometry and the composition of the structure (Fig. 8).The objective of this research work is thus to evaluate the energy that can be dissipated bycomposite tubular structures, to compare the absorption values induced by compositestructures of different compositions, and/or bi-materials, and, finally, to provide a finiteelement model representing the behavior of composite structure submitted to compressionuntil damage and fracture of the structure.It has consequently been established that in static loading, a unidirectional laminate orientedat 0° and stabilized by woven plies strongly meets the expectations in terms of energydissipation, but that is not the case in dynamic loading. In this case, a 90° stratification seemsmore adequate. Incidentally, an inner constrained containment is more effective in most cases,reducing the initial peak load without drastically reducing the SEA value.

Le coulis de glace est un fluide composé d'une phase solide, la glace, et une phase liquide, une solution aqueuse. Dû à la chaleur latente de la fonte de la glace, le coulis peut extraire une plus grande quantité d'énergie que le fait un fluide monophasique. Dans un premier temps, les corrélations permettant de calculer les propriétés thermophysiques des solutions aqueuses, soient la concentration de glace, la densité, la viscosité, la conductivité thermique et l'enthalpie, sont établies.Le coulis à base de propylène glycol est pris comme exemple afin de présenter la démarche suivie. Pour les trois autres additifs, l'éthylène glycol, le chlorure de calcium et le chlorure de sodium, seuls les coefficients des corrélations sont présentés. Dans un deuxième temps, une série d'expérimentations a été réalisée sur un échangeur de chaleur tubes et calandre afin d'évaluer les pertes de pression et le transfert de chaleur du coulis fait à base d'éthylène glycol. La perte de pression dans les tubes, ainsi que la température à l'entrée et à la sortie et le débit massique de chaque fluide ont été mesurés. Les mesures ont démontré que la concentration de glace a un impact plus grand sur le transfert de chaleur quand le débit de coulis est faible. De plus, le débit de coulis a un impact plus grand sur les pertes de pression que la concentration de glace. Dans un troisième temps, le transfert de chaleur en régime transitoire entre la patinoire, les fondations du bâtiment et le sol extérieur a été calculé par un modèle numérique d'aréna. Deux réfrigérants secondaires, la saumure et le coulis, servant à refroidir la glace sont comparés. La simulation montre que la température de la glace est plus uniforme avec le coulis qu'avec la saumure. Une analyse paramétrique est menée afin d'évaluer l'effet de la diminution du débit de réfrigérant secondaire sur la température de la surface de la glace et sur la puissance de pompage.

Les nanotubes de carbone ou le graphène sont des formes allotropiques du carbone prometteuses pour un large domaine d'applications, mais des modifications de leur surface carbonée sont nécessaires pour leur manipulation et mise en forme. La fonctionnalisation covalente est un des moyens utilisés avec succès dans ce cadre, même si les modifications induites ne sont pas contrôlables. Les travaux réalisés au cours de cette thèse concernent l'utilisation de la réduction chimique des nanotubes et autres nanoformes de carbone, nanocornes, graphène ou nanodisques, pour d'une part obtenir des solutions stables et concentrées dans une gamme de solvants dépendant du type de nanoforme et d'autre part fonctionnaliser de manière covalente les différents types de surface carbonée de ces objets. Dans le cas des nanotubes, des molécules acceptrices ou donneuses d'électrons ont ainsi été greffées permettant la formation d'ensembles donneur-accepteur. D'autre part, le nombre de fonctions chimique greffées a pu être contrôlé, préservant ainsi les propriétés électroniques des nanotubes.

La prédiction des instabilités fluide-élastique qui se développent dans un faisceau de tubes est importante pour la conception des générateurs de vapeur dans les centrales nucléaires, afin de prévenir les accidents liés à ces instabilités. En effet, ces instabilités fluide-élastique, ou flottements, conduisent à une fatigue vibratoire des matériaux, voire à des chocs entre les tubes, et par la suite, à des dégâts importants. Ces aspects sont d'une grande complexité pour les applications scientifiques impliquant l'industrie nucléaire. Le présent travail est issu d'une collaboration entre l'EDF, le CEA et l'IMFT. Elle vise à améliorer la simulation numérique de cette interaction fluide- structure dans le faisceau de tubes, en particulier dans la gamme de paramètres critiques favorisant l'apparition d'un amortissement négatif du système et de l'instabilité fluide-élastique. / The prediction of fluid-elastic instabilities that develop in a tube bundle is of major importance for the design of modern heat exchangers in nuclear reactors, to prevent accidents associated with such instabilities. The fluid-elastic instabilities, or flutter, cause material fatigue, shocks between beams and damage to the solid walls. These issues are very complex for scientific applications involving the nuclear industry. This work is a collaboration between EDF, CEA and IMFT. It aims to improve the numerical simulation of the fluid-structure interaction in the tube bundle, in particular in the range of critical parameters contribute to the onset of damping negative system and the fluid-elastic instability.

Orientador: Ciro Moraes de Barros / Coorientador: Anthony César de Souza Castilho / Banca: Mário Binelli / Banca: Luiz Gustavo de Almeida Chuffa / Resumo: O oviduto possui papel essencial na reprodução de mamíferos, promovendo um microambiente favorável para a maturação oocitária, estocagem e capacitação do espermatozoide, fertilização, transporte dos gametas e desenvolvimento inicial do embrião. Anatomicamente e funcionalmente, o oviduto é dividido em três regiões principais: infundíbulo, ampola e istmo. O oócito e o espermatozoide entram nos lados opostos do oviduto, respectivamente no infundíbulo e istmo, e são transportados até a ampola, local onde ocorre a fertilização. O sucesso reprodutivo está diretamente ligado a temporização apropriada do transporte dos gametas ao local da fertilização, bem como, a precisão no tempo de transporte do embrião até o útero, para a aquisição da capacidade de implantação. A coordenação e regulação das funções do oviduto são complexas e estão sob efeitos endócrinos, parácrinos e autócrinos, os quais alteram temporalmente e espacialmente a transcrição e tradução de diversos fatores. Diante disso, o presente trabalho visou avaliar o efeito de biotecnologias reprodutivas, especificamente da superestimulação ovariana, bem como de características genéticas e fisiológicas reprodutivas no perfil transcricional de diversos fatores no oviduto bovino. Para tanto, foram avaliados os efeitos da indução de múltiplas ovulações em vacas da raça Nelore (dados apresentados no primeiro manuscrito), bem como os efeitos da influência da seleção genética de animais com alta contagem folicular em novilhas da raça Nelore e Aberdeen Angus, no período inicial pós ovulação (dados apresentados no segundo manuscrito), na expressão de genes relacionados ao transporte de gametas e fertilização. Os resultados demonstram que a superestimulação ovariana modula a expressão de alguns genes relacionados à contratilidade do oviduto em vacas da raça Nelore e que a ovulação é principal fator responsável por controlar ... / Abstract: The oviduct has an important role in mammal reproduction, promoting a favorable microenvironment for oocyte maturation, sperm storage and capacitation, fertilization, transport of gametes and early embryo development. Anatomically and functionally, the oviduct is divided in three regions: infundibulum, ampulla and isthmus. The oocyte and the sperm enter in opposite sides of the oviduct, respectively infundibulum and isthmus, and are transported to the fertilization site, the ampulla. Reproductive success is directly related to appropriate timing of gamete transport to the fertilization site, as well as a precise time of embryo transport to the uterus, to obtain the capacity of implantation. The coordination and regulation of oviductal functions are complex and under endocrine, paracrine and autocrine effects, which temporally and spatially alter the transcription and translation of several factors. Therefore, this study aimed to evaluate the effect of reproductive biotechnologies, specifically ovarian superstimulation, as well as genetic and physiological reproductive characteristics in the transcriptional profile of several factors in the bovine oviduct. To do so, we evaluated the effects of inducing multiple ovulation in Nelore cows (data presented in the first manuscript), and the effects of the influence of genetic selection of animals with high follicle count in Nellore and Aberdeen Angus heifers, in the initial period post-ovulation (data presented in the second manuscript), in gene expression related to gametes transport and fertilization. The results demonstrated that ovarian superstimulation modulates the expression of some genes related to oviductal contractility in Nelore cows and ovulation is the main factor responsible for transcriptional control in bovine oviduct, with less or no impact of breed and ovarian follicle count / Mestre

O processo estudado utilizou tubos cerâmicos porosos fabricados predominantemente com alumina e produzidos pela técnica da colagem de barbotina e sinterizados a temperaturas próximas a 1450 graus Celsius, para seleção de uma temperatura. O meio micro poroso foi caracterizado pela técnica de porosimetria por intrusão de mercúrio, apresentando tamanho médio de poro de 0,5 'mü'm. Os tubos foram submetidos à impregnação com solução de citrato de zircônio (precursor) por capilaridade. Posteriormente, os tubos foram calcinados e tratados termicamente até 600 e 900 graus Celsius, com o objetivo de eliminar componentes orgânicos voláteis e transformar o precursor no óxido metálico. A impregnação foi realizada em diferentes proporções e os tubos microporosos foram testados na bancada de micro-filtração, onde foram variados parâmetros fluidodinâmicos do processo (Reynolds e pressão transmembrana) e analisada as propriedades físico-químicas do volume de permeado, através de medidas da concentração de carbono orgânico total (TOC), condutividade elétrica, pH e a caracterização da mistura (concentrado) através de microscopia óptica. O meio micro poroso impregnado foi caracterizado por microscopia eletrônica de varredura (MEV), para analisar a morfologia do material impregnado e sua composição qualitativa. Os resultados do fluxo de permeado foram analisados e observou-se que os melhores resultados quanto ao fluxo transmembrana foram obtidos para o tubo impregnado a 900 graus Celsius. O tubo impregnado a 600 graus Celsius apresentou melhor desempenho relativo à desemulsificação, por apresentar menores valores de TOC. Em relação ao processo de transferência de massa, o tubo impregnado 900 graus Celsius obteve maiores valores de Sherwood, portanto a temperatura após impregnação influenciou no transporte de massa durante o processo de separação. A retenção da fase óleo analisada através de medidas de TOC foi de até 99%. / The studied process used porous ceramic tubes manufactured predominantly with alumina and produced by the technique of the collage with barbotina and sintered to close temperatures for 1450 Celsius degrees, for selection of a temperature. The microporous enviroment was characterized by mercury porosimetry, presenting medium size of pore of 0,5 'mü'm. The tubes were submitted to the impregnation with solution of citrate of zirconium (precursory) by capillarity. Later on, the tubes were burned and thermally treated up to 600 and 900 Celsius degrees, with the objective of to eliminate volatile organic components and to transform the precursory in the metallic oxide. The impregnation was accomplished in different proportions and the microporous tubes were tested in apparatus of microfiltration process, where were varied fluid dynamics parameters of the process (Reynolds and transmembrane pressure) and analyzed the physical-chemical properties of the volume of permeated, through measures of the concentration of total organic carbon (TOC), electric conductivity, pH and the characterization of the mixture (concentrated) through optical microscopy. The enviroment impregnated microporous was characterized by scanning eletronic microscopy (SEM), to analyze the morphology of the impregnated material and its qualitative composition. The results of the flow of having permeated were analyzed and it was observed that the best results with relationship to the transmembrane flux were obtained for the tube impregnated for 900 Celsius degrees. The tube impregnated for 600 Celsius degrees presented better relative acting to the demulsifying, for presenting smaller values of TOC. In relation to the process of mass transfer, the impregnated tube 900 Celsius degrees obtained larger values of Sherwood, therefore the temperature after impregnation influenced in the mass transport during the separation process. The retention of the phase oil analyzed through measures of TOC was of up to 99%.

Os tubos de Geradores de Vapor em Reatores Nucleares do tipo PWR são submetidos a diferentes níveis de tensões e carregamento em altas temperaturas, reduzindo sua vida útil devido o surgimento de defeitos e corrosão. A inspeção por Correntes Parasitas é um ensaio não destrutivo usado para diagnosticar defeitos de corrosão e descontinuidades na superfície externa e interna em tubos de trocadores de calor. Esses tubos estão sujeitos a danos por diferentes mecanismos de degradação mecânica e química, tais como trincas por fadiga e corrosão sob tensão. Os sinais de inspeção por Correntes Parasitas são afetados por diferentes ruídos dificultando sua análise pelo inspetor. Esse trabalho apresenta os resultados da análise dos sinais de Correntes Parasitas usando a Transformada de Hilbert-Huang (THH) funcionando como filtro de ruídos (De-noising), como uma técnica alternativa de processamento e análise de sinais. A Transformada de Hilbert-Huang teve esse nome atribuído pela agência espacial norte-americana (NASA) para o resultado da reunião de dois processos, um método de decomposição empiricamente modal (Empirical Mode Decomposition EMD), seguido da análise espectral de Hilbert (Hilbert Spectral Analysis HSA). Os sinais de inspeção por correntes parasitas possuem características de transiente, não estacionário e não linear. A transformada de Hilbert-Huang aplicada neste trabalho forneceu dois recursos alternativos em processamento de sinais; o pré-processamento que funcionou como filtro de ruídos, e outro de análise de sinais, responsável pela identificação das características tempo-frequência-energia do sinal. / The nuclear power plant steam generator tubes are subjected to different levels of stress and loading at high temperatures, reducing its lifetime due to the development of defects and corrosion. The Eddy Current Testing (ECT) is a nondestructive testing used to diagnose defects of corrosion and discontinuities in the inner and outer surface of heat exchanger tubes. These tubes are subject to failure by different mechanisms of chemical and mechanical degradation such as fatigue and stress corrosion crack. The ECT signals are affected by different noises making the analysis a difficult task to the inspector. This dissertation presents the results of the main characteristics from the ECT signals using the Hilbert-Huang Transform (HHT) as an alternative method for the processing and signal analysis. The Hilbert-Huang Transform has its name given by the American National Aeronautics and Space Administration, NASA, as the result of Empirical Mode Decomposition (EMD) and the Hilbert Spectral Analysis (HSA) methods. The Eddy Current signals are transient, nonstationary and nonlinear. The Hilbert-Huang Transform applied in this work provided two alternative proceedings in signal processing, one in signal pre-processing acting as noise filter (De-noising) and another as signal analysis, which identifies the characteristics of signal time-frequency-energy.

A tecnologia de evaporação por filme descendente pode ser empregada em diferentes aplicações como processos químicos, petroquímicos, dessalinização de água, ciclos de refrigeração por absorção, OTEC Ocean termal energy conversion primer, só para mencionar alguns. No entanto, esta tecnologia tem demandado númerosos estudos devido a que ainda não é totalmente bem entendida, inclusive certos fenômenos básicos como são os problemas de distribuição do líquido, comportamento da espessura do filme e, sua transferência simultânea de calor e massa, sendo sujeito a vários estudos tanto numéricos quanto experimentais. Este trabalho foi focado no estudo da transferência simultânea de calor e massa, espessura do filme a os problemas de distribuição na vaporização de filme de água sobre tubos. Para isto, foi construída uma bancada de teste experimental, disponível para mensurar as seguintes variáveis; (a) temperatura da superfície dos tubos evaporadores, (b) espessura do filme descendente, (c) vazões mássicas, (d) potência elétrica fornecida aos tubos evaporadores, e (e) registro fotográfico infravermelho. O presente trabalho foi estruturado em dois aspectos principais; (1) avaliação do coeficiente de transferência de calor e massa, e (2) medição da espessura do filme descendente. Para os dois casos foram analisados os mecanismos de transferência de calor: sensível e latente. Para o primeiro ponto foram calculados os coeficientes local e médio de transferência de calor. No último ponto, usou-se um mecanismo formado por um micrômetro de elevada precisão aliado a um sistema elétrico para mensurar a espessura do filme líquido, sendo comparada com a teoria de Nusselt. Encontrou-se que há uma forte dependência da transferência de calor e massa com a espessura do filme descendente para a região laminar de Reynolds ente 160 a 950, implicando uma diminuição da taxa de transferência de calor com o aumento do Reynolds, já que a espessura de filme impôs uma maior resistência térmica. Além disso, avaliou-se o sistema de medição da espessura do filme com 25% de divergência da teórica de Nusselt. / Falling film evaporation technology can be used in different applications such as water desalination, refrigeration and ar-conditioning absorption cycles, OTEC (ocean thermal energy conversion primer), petrochemical and chemical process industries. This technology still demands númerous studies due to the lack of a complete understanding, even some basic phenomena such as the liquid distribution problem, liquid film thickness behavior and the heat and mass transfer coefficients are subject of intense experimental and numerical studies. This work has analyzed experimentally the heat and mass transfer coefficient, falling film thickness and the distribution system in water vaporization over tubes. For that, it was built an experimental setup, which has been measured the following; (a) tube wall temperature, (b) falling film thickness, (c) mass flow rate, (d) electrical power supplied to the evaporator tube, (e) infrared images. The present work has been structured in two mean aspects; (1) heat and mass transfer coefficient evaluation, and 2) falling film thickness measurement. In both topics, the two heat transfer mechanisms were analyzed: sensible and latent heat transfer. For the first topic, it has been analyzed the local and the overall heat transfer. For the second part, the method used a novel mechanical configuration (leverage effect), which improves the micrometer reading with more precision to obtain the film thickness, which was compared with the Nusselt theory. The experimental data showed that there is a strong dependence between the heat and mass transfer coefficient with the film thickness in the laminar region (Reynolds between 160 e 950), implying a decreasing of the heat transfer rate when the Reynolds increased, due to that the film thickness imposes a greater thermal resistance. Moreover, the study found the film thickness with a divergence of 25 % when it was compared with the theoretical Nusselt film thickness.