L’objectif principal de la thèse était d’identifier les processus limitants et les phénomènes de dégradation intervenant lors du cyclage d’un accumulateur Li/S, et d’expliciter l’évolution des performances électrochimiques au cours du temps. Pour ce faire, une cellule électrochimique a été développée permettant de réaliser des caractérisations à l’ESRF par diffraction et absorption des rayons X en mode operando. Ces deux techniques complémentaires ont permis de mettre en évidence des changements morphologiques importants et des cinétiques de réactions limitées par le transport de matière au sein de la structure 3D de l’électrode positive de soufre. L’oxydation/réduction de l’électrode négative de lithium a également été caractérisée, permettant de mettre en évidence une évolution hétérogène de l’interface lithium/électrolyte, fonction de la densité de courant, induisant une diminution des performances électrochimiques en cyclage. / The main objective was to identify the degradations phenomena and the limiting processes occurring while cycling Li/S accumulators to therefore put in relation the electrode morphology, the cell design, the electrochemical performances and the degradations phenomena. A new design of operando cell has been developed to be suitable with ESRF experiments. Operando Absorption and X-ray Diffraction tomography technics were performed. Thanks to both technics, the morphological changes and transport limitation kinetics along the 3D positive electrode have been evidenced. In addition, the lithium electrode/electrolyte interface has been characterized and heterogeneous stripping/plating has been evidenced, leading to low electrochemical performances while cycling.

O crescimento significativo da capacidade instalada de produção de laminados de alumínio no País deve-se ao crescente consumo de latas para bebidas, um sinal de confiança dos consumidores e de sucesso sem precedentes em termos de solução para o mercado de embalagens. A lata de alumínio pode ser reciclada infinitas vezes. Por isso, consagrou também sua unanimidade, devido ao enorme benefício da reciclagem, que reduz o consumo de energia para a produção do alumínio, preserva o meio ambiente, movimenta a economia, gerando empregos e fonte de renda na coleta, e promove a educação dos cidadãos para o desenvolvimento sustentado. O foco deste trabalho é o estudo da alteração da textura de uma liga de alumínio 3104-H19 nas várias etapas do processo de estampagem das latas de alumínio para bebidas através da análise dos resultados de mesotextura obtidos pelos método MEV( Microscópio eletrônico de Varredura)- EBSD (Electron Backscatter Diffraction), bem como a compreensão dos mecanismos da formação da textura e sua influência na conformação das latas de alumínio. A composição química da liga de alumínio foi avaliada através de espectroscopia de dispersão de energia (EDS-MEV) e espectrometria de emissão ótica. Analisou-se sua microestrutura através de microscopia ótica e microscopia eletrônica de varredura (MEV). Realizou-se o ensaio de textura cristalográfica pelo método (SEM- EBSD) nas etapas de estampagem do corpo da lata e em ângulos de zero, 45 e 90 graus em relação a direção de laminação. Avaliou-se o resultado da textura cristalográfica através de Figuras de Polo. A análise microestrutural do laminado revelou dois tipos de compostos intermetálicos com morfologia distinta, Al6(Fe,Mn) e Al12(Fe,Mn)3Si, espalhados não homogeneamente, junto a dispersoides bem distribuídos na matriz de alumínio. Observou-se que na chapa laminada a textura a zero 45 e 90 graus são diferentes e à medida que os estágios de conformação do corpo da lata vão avançando as texturas a 45 e 90 graus vão se modificando e ficando semelhantes a da textura a zero grau (direção de laminação). A textura típica de deformação para ligas de alumínio, latão {110} e cobre {112}, junto a textura Goss {110}, estavam balanceadas pela textura cubo {001}, típica de recristalização. / The significant growth in the installed capacity of aluminum rolled products in Brazil is due to the increasing consumption of beverage cans, a sign of consumer confidence and unprecedented success in terms of solution for the packaging market. The aluminum can be recycled endlessly. Therefore, it also consecrated its unanimity, due to the enormous benefit of recycling, which reduces energy consumption for the production of aluminum, preserves the environment, moves the economy, generates jobs and sources of income in the collection, and promotes the education of citizens for sustainable development. The focus of this work is the study of the alteration of the texture of a 3104-H19 aluminum alloy in the various stages of the process of stamping aluminum cans for beverages by comparing the mesotexture results obtained by SEM (Scanning Electron Microscope) EBSD (Electron Backscattered Diffraction), as well as the understanding of the mechanisms of texture formation and its influence on the conformation of aluminum cans. The chemical composition of the aluminum alloy was evaluated using energy dispersive spectroscopy (EDS-MEV) and optical emission spectrometry. Its microstructure was analyzed by optical microscopy and scanning electron microscopy (SEM). The crystallographic texture test (SEM-EBSD) was carried out in the stamping stages of the can body and at angles of zero, 45 and 90 degrees with respect to the rolling direction. The result of the crystallographic texture was evaluated through Polo Figures. Microstructural analysis of the laminate revealed two types of intermetallic compounds with distinct morphology, Al6 (Fe, Mn) and Al12(Fe, Mn)3Si, dispersed in a homogeneous manner, together with dispersoides well distributed in the aluminum matrix. It was observed that in the laminated plate the texture at zero 45, 90 degrees are different, and as the stages of conformation of the body of the can advance the textures at 45 and 90 degrees, they are changing and being similar to the texture at zero degree (direction of rolling). The typical deformation texture for aluminum alloys, brass {110} and copper , together with Goss texture , were balanced by the cube texture {001}, typical of recrystallization.

In this work, the influence of different cooling rates (5, 20, 50 and 100 °C/s) on the microstructure and mechanical properties of Laser Metal Wire Deposited (LMwD) Ti-6Al-4V was investigated, this was done using a thermal-mechanical physical simulation system (Gleeble 3800, DSI). Two different soak times above β transus (held at 1100 °C), 5 and 40 s, were used and after cooling to 150 °C, the samples were tensile tested. The samples were characterized with optical microscopy (OM) and scanning electron microscopy (SEM) and hardness testing. The results were then compared, both with each other and with two reference samples, that were only heated to 150 °C and then tensile tested. It was found that for the lowest cooling rate, 5 °C/s, the microstructure had transformed from a basketweave α microstructure to a colony α microstructure in the center of the specimen waist where heating was most efficient. Ultimate tensile strength (UTS) was found to be in the range of 858 – 977 MPa, with the highest average being recorded for the reference samples, similar results were noted for the strain, with a range of  ⁓5 – 14 %, where the highest recorded average was for the reference samples. However, the extensometer used was not optimized for this kind of test, therefore percent reduction of area (RA) measurements were performed. The RA measurements produced a significantly different result than that obtained from the testing, a large scatter in the ductility was found, possibly due to thermal instability that occurred during testing. Overall, the microstructure appears to be relatively stable over the cooling range of 20 - 100 °C/s, no major differences were observed, the microstructure consisted of a homogeneous basketweave α microstructure, with little to no change in the measured average α lath thickness.

Malgré le bénéfice apparent des modules bifaces, cette technologie souffre toujours d'un manque de visibilité sur les gains en performance qu'elle apporte. Dans cette thèse, nous étudions le cas de modules bifaces verticaux intégrés sur une façade et nous évaluons plusieurs architectures de modules spécifiques aux contraintes électriques et optiques des applications bifaces. Nous avons mis en place une méthodologie d'évaluation des performances électriques annuelles de modules bifaces basée sur trois outils : un dispositif de caractérisation en double éclairement au simulateur solaire, un banc de test modulable en environnement extérieur et son modèle optique avec un logiciel de tracé de rayons. Les résultats expérimentaux obtenus à court terme dans différentes configurations du banc ont permis de valider notre modèle optique. Ainsi, les performances annuelles de l'application façade verticale à échelle réduite ont pu être maximisées suivant les paramètres importants de l'application et du module. En particulier, les avantages d'une architecture à cellules découpées, à interconnexion en parallèle et à verres texturés ont été évalués séparément vis-à-vis des pertes résistives qui surviennent en double éclairement et du rayonnement souvent non-uniforme et diffus incident sur la face arrière du module. Ce travail à échelle réduite a permis de dresser des perspectives pour un module de taille réelle et d'initier des études à l'échelle du système biface. / Despite the apparent benefits of bifacial modules, their application still suffers from a lack of visibility on the performance gain that they can actually provide. In this thesis we consider the specific application of vertically oriented bifacial modules, notably for facade integration. We also consider several innovative module architectures to work around some of the electrical and optical constraints of bifacial modules. We have developed a methodology to evaluate the annual electrical performance of bifacial modules based on three tools. Firstly, a double illumination characterization setup is used in a solar simulator for comparing module architectures. Then, a reduced scale outdoor test bench allows us to evaluate bifacial module performance in a variety of configurations. Finally, a ray-tracing model validated with short-term outdoor data leads to the annual electrical performance. This methodology allowed us to find optimal performance according to the most important parameters of application and module. Specifically, a module architecture using half-cut cells, a parallel cell interconnection and textured glasses have been analysed with respect to their influence on the resistive losses which occur in double illumination as well as to their influence on the effect of non-uniform and diffuse irradiance on the backside of the module. This work enabled us to propose real size module architectures and to launch studies at the bifacial system level.

L’essor des matériaux composites à matrice céramique dans les domaines de l’aéronautique, du spatial et du nucléaire force le développement de nouveaux matériaux et procédés associés afin de répondre à l’exigence toujours plus poussée de ces secteurs d’activité. La course à la réduction des coûts de fabrication a notamment contribué à ces développements. Dans cet objectif, le LCTS contribue à développer un moyen original et alternatif pour la synthèse d’interphases et de matrices des CMC par densification du renfort fibreux : le procédé dit « de caléfaction ». Ces travaux de recherche ont pour principal objectif l’étude de précurseurs originaux pour l’élaboration de matériaux pyrocarbone (pyC) et Si-O-C par ce procédé. Ce mémoire s’articule ainsi autour de 2parties expérimentales que sont i) l’élaboration de revêtements pyC à partir de précurseurs alcools et ii)l’élaboration de revêtements Si-O-C à partir de précurseurs organosilylés.Les diverses techniques de caractérisation physico-chimique utilisées, couplées aux nombreuses expériences réalisées dans ces travaux ont permis de relier la structure et/ou la composition chimique des revêtements obtenus aux paramètres expérimentaux utilisés (précurseurs, températures et durées d’élaboration). Des conditions optimales de préparation de PyC de très haute qualité à partir d’alcools ont été obtenues. Quant au système Si-O-C, il est montré que la structure et la composition des dépôts dépendent des conditions. / The growth of ceramic matrix composite (CMC) in the fields of aeronautic, spatial and nuclear pushes the development of new material and associated processes in order to answer to the tough requirements in this business sectors. Fabrication cost savings, in particular, has helped these improvements. In this aim, the LTCS has contributed to develop an original and alternative device for the synthesis of CMC’s interphases and matrices : the “film boiling densification”.This PhD as for key objective the study of original precursors for PyC and Si-O-C fabrication using this process. This manuscript is divided into two experimental parts dedicated to : i) the fabrication of carbon coatings from alcohols and ii) the fabrication of Si-O-C coatings from silylated precursors.The diverse characterization technics coupled to the numerous experiments permitted to connect the coatings structure and/or the chemical composition to the experimental parameters (precursor, temperature,duration). Optimal conditions were found for the preparation of high quality PyC from alcohols.For Si-O-C system, it is show that structure and chemical composition depends on experimental conditions.

Although tremor is the most common movement disorder, there are few non-invasive treatment options. One of the obstacles to creating effective tremor suppression devices is our lack of understanding regarding where tremor originates (which muscles), how it propagates through the limb (to which degrees of freedom, DOF), and where it manifests most severely (which DOF). To investigate these questions, we created a simple, linear time-invariant model to simulate tremor, with tremorogenic muscle activity input (in the 15 major superficial muscles from the shoulder to the wrist) and joint displacement output (in the 7 major upper limb DOF). The model included excitation-contraction dynamics, musculoskeletal geometry (muscle moment arms) and the mechanical impedance (inertia, damping, and stiffness) of the limb. From our simulation results, we determined four principles of tremor propagation. First, the distribution of tremor depends strongly on musculoskeletal dynamics. Second, the spreading of tremor is due to inertial coupling (primarily) and musculoskeletal geometry (secondarily). Third, tremor spreads narrowly in the sense that most of the tremor caused by a muscle occurs in a small number of DOF. Lastly, assuming uniform distribution of tremorogenic activity among upper-limb muscles, tremor increases proximal-distally, and the contribution from muscles increases proximal-distally.

[pt] O correto planejamento de novas redes de comunicação sem fio de voz e dados representa um grande desafio ao incluir serviços cada vez mais avançados com diferentes requisitos de qualidade, suporte a mobilidade, altas taxas de transmissão e capacidades de tráfego elevadas. Os ambientes nos quais estas redes operam são dos mais diversos e contemplam desde na áreas abertas até centros urbanos com alta densidade de edificações. O presente trabalho apresenta resultados experimentais que permitem caracterizar o canal de radio-propagação num ambiente urbano com mobilidade do receptor. Como resultado de campanhas de medições, são identificados modelos do canal que permitem ao projetista da rede definir a melhor configuração de parâmetros e critérios de projeto para a implantação de uma rede móvel de acesso sem fio em banda larga. As medições foram realizadas nos bairros da Gávea, Leblon e Lagoa, no Rio de Janeiro, com estação transmissora instalada na PUC-Rio (prédio LEME) na frequência de 3,5 GHz, destinada para novos serviços móveis. Os principais resultados obtidos são: o desenvolvimento de uma metodologia de medição simples e precisa, utilizando a técnica OFDM, e das ferramentas de software para pré-processamento e analise de dados; o desenvolvimento de modelos semi-empíricos para a previsão da perda média de propagação; a obtenção de perfis de retardo do canal e dos valores médio e desvio padrão do retardo em condições de visibilidade (LOS) e obstrução (NLOS), e de expressões empíricas para sua estimativa; a obtenção do valor médio das amplitudes relativas dos multipercursos e sua modelagem em função do valor de retardo relativo. / [en] Best practices of radio planning for new wireless networks with mixed trac of voice and data are a big technical challenge due to the need to provide of advanced services with different quality requirements, high data throughput, mobility and high traffic demands. Environments for operation of this kind of networks are diverse and include open areas with low population density as well as urban centers. This thesis presents experimental results obtained to characterize the wideband radiopropagation channel on urban environments with a mobile receiver. The analysis of measured data allows the identification of channel models and propagation mechanisms needed for the design engineer to define the best parameter configuration and project criteria in the deployment of a wideband mobile wireless network. The measurement campaign was executed on Gavea neigborhood in Rio de Janeiro city with a transmitter station located in a PUC-Rio university building (Lcme Building) operating at 3,5 GHz, frequency used for the new wideband mobile services. The main results are: the development of a simple and precise methodology for measuring, using the OFDM technique OFDM, and the software tools for pre-processing and analysis; the development of semi-empirical models for predicting the average propagation loss in the urban environment; measurements of multipath delay profiles of the channel and the average values and standard deviation of the RMS delay spread in visibility (LOS) and obstruction (NLOS) conditions, and derivation of empirical expressions for their estimation; measurements of the average values of multipath amplitudes its modeling in function of the relative delay.

Magnetic permalloy nanostructures were fabricated onto a silicon wafer using electron beam lithography and a liftoff process. The lithography was performed with a Hitachi SU-70 SEM retrofitted with a Nabity NPGS lithography conversion kit. PMMA of 950kDa molecular weight was used as the photoresist. Features were either nanowires, nanodots, or elliptical or rectangular nanostructures. The nanowires had dimensions of 15µm x 200nm x 40nm, the nanodots had diameters of 145nm and thickness of 12nm, and the ellipses and rectangles had dimensions of 110nm x 50nm x 13nm. Characterization of the nanostructures was performed using the same Hitachi SEM as well as a Digital Instruments DI 3100 Nanoscope IIIa AFM used in magnetic force imaging mode. The SEM was used to measure lateral dimensions of the features and to capture images of features for proper documentation and for external simulation studies. The MFM was used to capture magnetic images of the samples to determine the magnetic state of the nanowires or arrays.

Abstract not available

<p> </p><p>Radioactive waste has been accumulated at CERN as unavoidable consequence of the use of particle accelerators. The elimination of this waste towards the final repositories in France and Switzerland requires the determination of the radionuclide inventory. In order to calculate the residual induced radioactivity in the waste, it is necessary to determine the spectra of secondary particles which are responsible for the material activation. In complex irradiation environments like in an accelerator tunnel it is expected that the secondary particle spectra vary with the characteristics of the machine components in a given section of tunnel. In order to obtain the production rates of the radionuclides of interest the spectra of secondary particles are to be folded with the appropriate cross sections. Though technically feasible, it would be impractical to calculate the particle spectra in every area of any machine and for all possible beam loss mechanisms. Moreover, a fraction of the waste has unknown radiological history, which makes it impossible to associate an item of waste to a precise area of the machine. Therefore it is useful to try to calculate “representative spectra”, which shall apply to a relatively large part of the accelerator complex at CERN. This thesis is dedicated to the calculation of representative spectra in the arcs of the 450 GeV proton synchrotron, SPS, at CERN. The calculations have been performed using the Monte Carlo code FLUKA. Extensive simulations have been done to assess the dependence of proton, neutron and pion spectra on beam energy, size of the nearby machine component and position with respect to the beam-loss point. The results obtained suggest that it is possible to define one single set of representative spectra for all the arcs of the SPS accelerator, with a minor error associated with the use of these. </p><p> </p>