Comme les propriétés physiques d'un matériau à l'échelle nanométrique sont largement dépendantes de la taille et de la forme des nanostructures, il est inutile de synthétiser de nouvelles compositions et morphologies. L'étude avancée de leur structure par les techniques de caractérisation usuelles (MET, MEB, DRX, Raman...) permettra de collecter toutes les informations nécessaires à la compréhension de leurs propriétés physiques (magnétiques, optiques, électriques). Dans ce manuscrit, nous décrirons plusieurs approches d'élaboration de nanostructures 0D, 1D et 2D multifonctionnelles afin de mieux connaître les paramètres qui contrôlent leur composition chimique et leur structure. De plus, ce travail de recherche a abouti à la synthèse de nouveaux matériaux à base d'oxyde et de carbure de fer. Des nanofibres magnétiques ayant des morphologies originales " Ruban " et " tube " ont été élaborées par la technique d'électrospinning en modifiant plusieurs paramètres expérimentaux : concentration de la solution, atmosphères de traitement thermique, température de recuit... De plus, des couches minces guidantes dopées par des nanostructures magnétiques ont été préparées par la technique dip-coating. Nous avons mené une étude complexe et détaillée sur les propriétés structurales de ces matériaux afin de définir les paramètres expérimentaux qui permettront d'obtenir des nano objets de bonne qualité. Dans un but ultime, nous souhaiterons explorer les possibilités d'application de ces matériaux qui présentent à la fois des caractéristiques électriques et magnétiques.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Thesis advisor: Sara Moorman / My grandfather passed away four years ago of cancer. Every family member made their way to Cape Cod during his last few days in order to say their good-byes. It was not until the day after the last grandchild said good-bye that my grandfather passed away. We all felt that he wanted to wait so he could say good-bye to all of us. I have talked to many people who have had similar experiences with family members and friends. Some people have held on to see people one last time; others have wanted to make another birthday, while others have wanted to see another holiday that is special to them. In the present study, I explored the death dip, death rise phenomenon. Specifically, I analyzed mortality rates around the New Year’s Day, Christmas, and Pioneer Day. I examined two days before and two days after the holiday within specific cities (Project 1: New York City, Los Angeles, Chicago; Project 2: Salt Lake City, Boise, Little Rock; Project 3: Atlanta, Oklahoma City, New Orleans) within a five-year period (1998-2002). The data observed found a death dip and death rise present for New Year’s in New York City and Chicago. There was not a death dip or death rise observed for Project 2, Project 3, or Los Angeles in Project 1. / Thesis (BA) — Boston College, 2014. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Sociology Honors Program. / Discipline: Sociology.

Most of the modern wind turbines are based on doubly fed induction generators (DFIG), with a back to back power converter connecting the rotor to the network. It is known that voltage dips at the stator terminals can cause overcurrents in the rotor windings, which could threaten the converter integrity. In order to protect the converter, several strategies have been proposed in technical literature, requiring in some cases the converter deactivation, which disables the control that the converter has over the power transference between the generator and the system. This last is not a desirable behavior since it can put on risk the voltage stability of the electric system. It is the aim of this dissertation to introduce and compare five of those protection strategies, through the computational simulation of their performance in case of balanced voltage dips. In order to achieve this, the electromagnetic dynamic model of the DFIG was theoretically developed, as well as the models of the strategies of interest. Subsequently, the computational model of the system was assembled in the software Matlabs Simulink to finally perform the desired simulations and its corresponding analysis. / A maioria das turbinas eólicas modernas é baseada em geradores de indução duplamente alimentados (GIDE), com um back to back conversor de energia que liga o rotor para a rede. Sabe-se que as quedas de tensão nos terminais do estator podem causar sobrecorrentes nos enrolamentos do rotor, que podem ameaçar a integridade do conversor. A fim de proteger o conversor, várias estratégias têm sido propostas na literatura técnica, exigindo, em alguns casos, a desativação do conversor, o qual desativa o controlo do conversor, que possui ao longo da transferência de energia entre o gerador e o sistema. Este último não é um comportamento desejável, uma vez que pode colocar em risco a estabilidade de tensão do sistema elétrico. É o objetivo desta dissertação apresentar e comparar cinco dessas estratégias de proteção, através da simulação computacional de seu desempenho em caso de quedas de tensão equilibrada. A fim de alcançar este objetivo, o modelo dinâmico eletromagnética do DFIG teoricamente foi desenvolvido, bem como os modelos das estratégias de interesse. Subsequentemente, o modelo computacional do sistema foi montado no software Simulink do Matlab para finalmente executar as simulações desejadas e sua análise correspondente.

O presente trabalho tem por finalidade analisar o problema do financiamento das empresas em crise no Brasil e a disciplina a ele conferida pela Lei n. 11.101/05, com enfoque no procedimento de recuperação judicial. Após uma breve análise das diversas causas da crise empresarial e de possíveis medidas saneadoras preliminares, inicia-se a discussão das premissas constitucionais do tratamento das empresas em dificuldade no Brasil e dos objetivos da lei falimentar em geral, para então ingressar nas soluções adotadas pelo direito brasileiro. Em seguida, tem início o escrutínio do tema central proposto, com destaque para seu escopo e importância, além da identificação dos meios, agentes e modalidades relacionados ao financiamento das empresas em dificuldade. Apresentado um sucinto panorama da matéria no direito estrangeiro, investiga-se o tema à luz do ordenamento pátrio, numa abordagem teórica e prática do financiamento das empresas em crise no Brasil e seus limitadores, assim como possíveis alternativas para mitigá-los. O problema é tratado, ainda, sob a perspectiva da governança corporativa e, por derradeiro, vislumbra-se sua eventual adoção na falência, com escoro no princípio da preservação da empresa, passando-se à conclusão. / The present work has the aim of analyzing the problem of financing for distressed companies in Brazil and the discipline granted to it by Law no. 11.101/05, with focus on the judicial reorganization procedure. After a brief analysis of the various causes of corporate crisis and the possible preliminary aid measures, a debate commences on the constitutional premises of the treatment of distressed companies in Brazil and the goals of bankruptcy law in general, after which the solutions adopted by Brazilian Law are examined. Next, the scrutiny of the proposed theme begins, with emphasis on its scope and importance, as well as the identification of the means, participants and categories related to the financing for companies in difficulties. After the presentation of a brief overview of the matter in foreign law, the same is investigated in light of the national legal system, under a theoretical and practical approach of financing for distressed companies in Brazil and its constraints, as well as the possible alternatives to mitigate them. In addition, the problem is treated from the perspective of the corporate governance and, last, a glimpse is taken into its eventual adoption in liquidation processes, with support in the principle of preservation of the company, culminating with the conclusion.

Made available in DSpace on 2014-06-11T19:31:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-18Bitstream added on 2014-06-13T21:02:05Z : No. of bitstreams: 1 sano_dmc_dr_bauru.pdf: 2390435 bytes, checksum: c70bb14dca9d8503f9a9ce373ebe90a2 (MD5) / Neste trabalho foi realizada a simulação numérica da fase líquida no processo de deposição de filmes finos pela técnica de molhamento (dip-coating), via sol-gel, utilizando como aplicação soluções precursoras de dióxido de estanho (Sn'IND. 2'). Dióxido de estanho é um semicondutor transparente de gap largo, amplamente utilizado em muitos tipos de dispositivos. Além da técnica convencional, o trabalho analisa uma nova proposta da técnica de deposição dip-coating onde a solução se encontra em uma temperatura diferente da ambiente. Para ambas as técnicas foram realizadas a modelagem matemática dos problemas e desenvolveu-se um método numérico apropriado baseado no método MAC (Marker and Cell). O problema foi resolvido em coordenadas cartesianas bidimensionais e as equações foram discretizadas pela técnica de diferenças finitas. Os resultados numéricos são visualizados por meio da distribuição de temperatura e vetores velocidade da solução precursora, que fornecem subsídios para investigação da influência dos vetores velocidade na obtenção de filmes com boas propriedades, em relação à uniformidade e homogeneidade. Verifica-se que estas características refletem diretamente na qualidade óptica dos filmes investigados, tornando-se parâmetros importantes para aplicações em dispositivos opto-eletrônicos. Através dos resultados numéricos verificou-se que nas regiões do fluido próximas ao substrato, os módulos dos vetores velocidade são maiores, há uma maior quantidade de material sendo depositado. Notou-se também, através da distribuição de velocidades em direção ao substrato que o filme tem uma melhor uniformidade na sua espessura quando os vetores velocidade possuem os valores de seus módulos mais próximos uns dos outros. Portanto, mudando os parâmetros iniciais de viscosidade, densidade, velocidade de imersão/emersão do substrato ou temperatura no fluido pode-se estudar o comportamento. / In this work, the numerical simulation of liquid phase in the thin film deposition, by the sol-gel-dip-coating technique, was carried out. The method was applied to tin dioxide (Sn'IND. 2') solutions. Tin dioxide is a transparent semiconductor of wide bandgap, extensively used in many types of devices. Besides the conventional procedure, this work analyses a new proposal for the deposition technique, where the solution is heated above room temperature. In both cases, the mathematical modeling was done and the appropriated numerical method was developed, based on MAC (Marker and Cell) approach. The problem was solved in two-dimensional Cartesian coordinates and the equations were discretized by the finite difference technique. The numerical results are visualized through temperature and vector velocity distributions in the precursos solution, yielding subsides to the investigation of the influence of vectors velocity in the deposition of good property films, concerning uniformity and homogeneity. It was verified that these characteristics point directly toward the optical quality of investigated films, becoming important parameters for application in optoelectronic devices. The numerical results allow verifying that in the fluid regions close to the substrate, where the velocity modulus is highter, there is a larger amount of material being deposited. It was also noticed, through the velocity distribution towards the substrate, that the film has a better thickness uniformity when the vectors velocity have modulus values closer to each other. Therefore, changing initial parameters such as viscosity, density, substrate dipping rate or fluid temperature, it is possible to evaluate the fluid behavior during the thin film deposition.

Most of the modern wind turbines are based on doubly fed induction generators (DFIG), with a back to back power converter connecting the rotor to the network. It is known that voltage dips at the stator terminals can cause overcurrents in the rotor windings, which could threaten the converter integrity. In order to protect the converter, several strategies have been proposed in technical literature, requiring in some cases the converter deactivation, which disables the control that the converter has over the power transference between the generator and the system. This last is not a desirable behavior since it can put on risk the voltage stability of the electric system. It is the aim of this dissertation to introduce and compare five of those protection strategies, through the computational simulation of their performance in case of balanced voltage dips. In order to achieve this, the electromagnetic dynamic model of the DFIG was theoretically developed, as well as the models of the strategies of interest. Subsequently, the computational model of the system was assembled in the software Matlabs Simulink to finally perform the desired simulations and its corresponding analysis. / A maioria das turbinas eólicas modernas é baseada em geradores de indução duplamente alimentados (GIDE), com um back to back conversor de energia que liga o rotor para a rede. Sabe-se que as quedas de tensão nos terminais do estator podem causar sobrecorrentes nos enrolamentos do rotor, que podem ameaçar a integridade do conversor. A fim de proteger o conversor, várias estratégias têm sido propostas na literatura técnica, exigindo, em alguns casos, a desativação do conversor, o qual desativa o controlo do conversor, que possui ao longo da transferência de energia entre o gerador e o sistema. Este último não é um comportamento desejável, uma vez que pode colocar em risco a estabilidade de tensão do sistema elétrico. É o objetivo desta dissertação apresentar e comparar cinco dessas estratégias de proteção, através da simulação computacional de seu desempenho em caso de quedas de tensão equilibrada. A fim de alcançar este objetivo, o modelo dinâmico eletromagnética do DFIG teoricamente foi desenvolvido, bem como os modelos das estratégias de interesse. Subsequentemente, o modelo computacional do sistema foi montado no software Simulink do Matlab para finalmente executar as simulações desejadas e sua análise correspondente.

Bibliography: leaves 116-127.

Uncoated defects in hot dip metal-coated steel products result from non-wetting of the steel surface by the molten alloy. The occurrence of uncoated defects is highly detrimental to product quality and production efficiency; uncoated defects compromise the appearance and anti-corrosion performance of hot dip metal-coated steel products and causes time delays in the application of subsequent surface treatments. Although many studies have been directed towards evaluating the effect of steel pre-heat temperature and oxidation on the formation of uncoated defects, fewer investigations have analysed how oil-derived residues remaining on steel surface following the cold rolling and furnace cleaning processes impact upon hot dip metallic coating quality. Furthermore, although a considerable amount of research has focussed on the process of deposit formation in lubricants used in other applications, the composition of oily residues remaining after the continuous annealing process, and the origins of these residues in the original rolling oil formulation, are poorly understood. The primary focus of the present work has been to gain an improved understanding of relationships between cold rolling oil composition, oil residue-formation characteristics and the occurrence of uncoated defects in 55Al-43.4Zn-1.6Si hot dip metallic coatings. Several key classes of rolling oil ingredients which decompose to leave high levels of thermally-stable residue have been identified. The thermal decomposition processes undergone by a variety ingredients within these classes have been studied under both oxidising and reducing conditions using Thermogravimetric Analysis (TGA) and Pressure Differential Scanning Calorimetry (PDSC) techniques, with chemical characterisation of the decomposition process and the resultant thermally-stable residue by infrared spectroscopy. Model blends of each ingredient in a typical cold rolling oil base ester have also been evaluated by TGA and PDSC to identify the impact of ingredient concentration and chemical structure on the amount of oily residue formed. The results of these investigations have been related to the impact of the ingredients on 55Al-43.4Zn-1.6Si hot dip metallic coating quality through the performance of industrial-scale hot dipping trials and hot dip simulation studies. In order to translate these results into a context more closely aligned with industrial conditions, the effect of processing variables, including furnace atmosphere and the availability/concentration of iron in contact with the rolling oil at the steel surface, on the decomposition process of a fully-formulated commercial cold rolling oil has also been investigated. The information gained can potentially be used to tailor operating conditions within the cold rolling/continuous hot dip metallic coating processes to enhance steel surface cleanliness. Finally, the deposit-forming tendencies of an array of different commercial cold rolling oils have been evaluated, leading to the development of a thermal analysis-based test for screening cold rolling oils with respect to their likely impact upon 55Al-43.4Zn-1.6Si hot dip metallic coating quality. This test, together with the understanding obtained on the effect of different rolling oil ingredients on hot dip metallic coating quality, can be used within the industry to formulate improved cold rolling oils.

Cette étude se place dans le contexte de réalisation de nouveaux matériaux à bas coût pour l'optique non linéaire. Pour cela, nous avons développé une approche nanocomposite, basée sur la fabrication de films Laponite/ LiIO3. Ces films sont réalisés à l'aide d'une technologie issue du procédé sol-gel puis recuits pour cristalliser LiIO3, matériau optiquement non linéaire, et ils présentent de bonnes potentialités en raison d'une concentration en nanocristaux actifs importante. De plus, la possibilité d'orienter les nanocristaux pendant la cristallisation par l'application d'un champ électrique permet d'obtenir un matériau présentant des propriétés optiques non linéaires comparables à celles des matériaux usuels de ce domaine.<br /><br />Au cours de ce travail, nous avons tout d'abord affiné le modèle de structure des films composites en mettant en évidence l'absence d'intercalation du LiIO3 dans l'espace interplaquette. Par la suite, nous avons optimisé le processus de dépôt des films. En particulier, nous avons amélioré sa reproductibilité en déterminant les principaux paramètres intervenant durant le process : pH, viscosité, température de recuit, champ électrique d'orientation. Par ailleurs, nous avons montré que le vieillissement des films, une limitation importante de ce procédé, pouvait être ralenti par le dépôt d'un film protecteur. Nous sommes ainsi parvenus à définir un ensemble de critères permettant la réalisation de films nanocomposites aux propriétés optiques linéaires et non linéaires satisfaisantes.<br /><br />Dans une seconde partie, nous nous sommes attachés à caractériser et modéliser les propriétés optiques linéaires et non linéaires des films nanocomposites Laponite/LiIO3. Nous avons cherché à établir le lien entre ces propriétés et la structure des films, et nous avons observé l'influence de la distribution d'orientation des nanocristaux d'iodate de lithium au sein de la matrice de Laponite sur les propriétés optiques non linéaire et pour le guidage. Cette étude, au caractère plus fondamental, a permis de construire des modèles adaptés à ce type de matériaux composites permettant d'interpréter les résultats expérimentaux et de prévoir les indices de réfraction et les propriétés optiques non linéaires de ce type de matériau.