This thesis investigates various active control aspects of large aperture telescopes; both Earth-based and space telescopes are considered.The first part proposes a concept of piezoelectric adaptive thin shell reflector for future space telescopes; it exhibits excellent areal density and stowability, and thus, paves the way to future large aperture space telescopes. Controlling the surface figure of spherical or parabolic shell with in-plane stresses induced by a piezoelectric layer raises two problems: (i) Doubly curved shells are significantly stiffer than flat plates (especially for the optical modes associated with hoop strains) and (ii) When using segmented electrodes with different voltages, the surface figure is subject to edge fluctuations with a characteristic length depending on the reflector curvature R_c and thickness t according to sqrt(R_ct). Accurate surface figure corrections require that the electrode size D_e satisfies D_e<sqrt(R_ct). This results in a very large number of electrodes, leading to ill-conditioning in the Jacobian matrix of the system; to solve this, a hierarchical approach is proposed to inverse the Jacobian, based on Saint-Venant's principle. This chapter also proposes a petal configuration which aims at reducing the hoop stiffness and improving the foldability of the reflector. A small scale technology demonstrator has been manufactured in the framework of the ESA-GSTP project Multilayer Adaptive Thin Shell Reflectors for Future Space Telescopes (MATS). The demonstrator includes a polymer substrate (PEEK) and a spin-coated PVDF-TrFE piezoelectric layer activated by independent electrodes; it is used to validate the manufacturing process and the independent actuation of the electrodes.The second part deals with control-structure interaction in flat deformable mirrors for Adaptive Optics. The problem arises because of the increasing size of AO mirrors, leading to lower resonance frequencies, and the control bandwidth requirements to achieve a good wavefront error compensation. This chapter studies the conditions for spillover instability and highlights the main parameters controlling the phenomenon: the ratio between the control bandwidth and the resonance frequency and the modal damping. Two methods for damping augmentation are discussed, one passive, using inductive shunting of piezoelectric elements, and the other active, using the wavefront sensor and the array of control actuators as a modal filter.The third part focuses on the field stabilization control of the tip/tilt mirror under wind disturbances of the E-ELT telescope (a distinctive feature of the E-ELT as compared to other smaller telescopes is that it will be a wind-limited instead of a seeing-limited telescope). A literature survey is conducted of the spectral content of the wind disturbances on large telescopes, with a special attention on the high frequency decay rate. The analysis confirms the adequacy of a decoupled design of the field stabilization (M5) control loop. However, the reaction torques necessary to control the tip/tilt mirror M5 have been found to depend critically on the asymptotic decay rate of the wind tilt disturbance. These torques act as a disturbance on the telescope structure and, if the wind disturbance does not decay fast enough with the frequency (a>-3), it may generate significant wavefront errors in the primary mirror M1, in a frequency range (30-100Hz) which may be difficult to eliminate by Adaptive Optics. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

Mudanças na política agrícola brasileira têm preconizado a adoção de mecanismos de mercado para o fortalecimento da comercialização, financiamento à produção e mitigação dos riscos agropecuários, tanto o climático, quanto o de mercado. O seguro rural é um dos instrumentos mais promissores nesse novo estágio da política agrícola, pois permite a administração do risco agrícola, ao mesmo tempo em que lastreia as operações de comercialização e financiamento agrícola. O seguro de receita emerge como um instrumento ainda mais robusto de estabilização a receita agrícola, na medida em que garante a variação de produtividade e preço, simultaneamente. O instrumento já é consolidado nos Estados Unidos e começa a ser estudado no Brasil. Por essa razão, a primeira parte do estudo, capítulo 2, visa analisar os planos de seguro existentes e indicar os modelos que devem ser fomentados no Brasil. Constatou-se que os modelos estadunidenses baseados no plano de Proteção de Renda (IP - Income Protection) e Receita Garantida (RA - Revenue Assurance), substituídos pelo plano Proteção de Receita (RP - Revenue Protection), são os mais adequados para iniciar o desenvolvimento dessa modalidade de seguro no Brasil. Na segunda parte do trabalho, capítulo 3, é apresentado modelo teórico de plano de seguro de receita, bem como procedimento metodológico de cálculo da taxa de prêmio, de modo univariado e bivariado. Aplicada a metodologia ao caso da soja no Paraná, concluiu-se que as taxas calculadas no estudo são inferiores às praticadas nos dois projetos experimentais existentes. O distanciamento entre as taxas praticadas no mercado e a diferença em relação às estimadas na nesta pesquisa indicam imprecisão no cálculo das taxas de prêmio e são evidências de superestimação das taxas pelas seguradoras. / Changes in Brazilian agricultural policies have advocated the adoption of market mechanisms for strengthening the marketing, the financing to production, and both climate and market farming risk mitigation. Rural insurance is one of the most promising instruments in this new stage of agricultural policy, for crop risk administration at the same time it serves as collateral to marketing operations and agricultural funding. The insurance revenue emerges as an even more robust stabilization of agricultural revenue instrument to the extent that it ensures the variation of productivity and price simultaneously. The instrument is already consolidated in the United States and begins to be studied in Brazil. For this reason, the first part of the study, Chapter 2, aims to analyze existing insurance plans and indicate the models that should be encouraged in Brazil. It was found that models based on U.S. Income Protection (IP) and Revenue Assurance (RA), replaced by the plan Revenue Protection are best suited to start the development of this type of insurance in Brazil. In the second part of the dissertation, Chapter 3, the theoretical model of revenue insurance plan is presented, as well as a methodology for univariate and bivariate premium ratemaking. The methodology was applied to the case of soybean in Paraná, and it was concluded that the rates calculated in this study are lower than those of the two existing experimental projects. The gap between the market rates and the difference in relation to the rates estimated in the study indicate inaccuracy in the calculation of premium rates and are evidence of rate overestimation by insurers.

Doctor of Philosophy / Department of Civil Engineering / Mustaque A. Hossain / Stacey E. Kulesza / Recycled concrete aggregate (RCA) is the byproduct of the demolition of concrete structures and pavements. An estimated 140 million tons of concrete waste is produced annually in the United States, most of which ends up in landfills. The use of RCA to replace quarried aggregates in paving projects is one way to utilize these materials and alleviate concerns regarding this increasing waste stream. RCA usage prevents waste concrete disposal into landfills, resulting in more sustainable use of mineral aggregate sources, and may further reduce costs associated with paving projects. However, the inferior physical properties of RCA, such as the presence of recycled mortar, complicate the incorporation of RCA into new concrete mixtures. State highway agencies such as the Kansas Department of Transportation are facing further issues with RCA from D-cracked pavements, raising the question if D-cracked aggregates should be used in paving operations. No known work has evaluated the effect of RCA from D-cracked pavements in subgrade soil stabilization. This study stabilized a low-plasticity clay in Kansas using RCA and three stabilizing materials (lime, Class C fly ash, and a combination of Portland cement and fly ash). Candidate mixtures with varying proportions of chemical stabilizers and D-cracked aggregates were evaluated using the standard Proctor, unconfined compressive strength, linear shrinkage, and California Bearing Ratio tests. Microstructure characteristics of selected mixtures were explored using scanning electron microscopy (SEM) and energy dispersive X-ray tests. Laboratory test results indicated that RCA, in conjunction with all cementitious materials except lime, improved clay strength, stiffness, and shrinkage properties. SEM results indicated that RCA caused a low void space and a dense arrangement of soil particles. RCA effectively improved evaluated mixture properties when an adequate soil-RCA bond was reached using chemical agents. The long-term performance of full-depth flexible pavements with stabilized mixtures as subgrade was assessed in the AASHTOWare Pavement ME Design (commonly known as MEPDG) software. The life-cycle cost of flexible pavements with stabilized mixtures was estimated for a 40-year design period. Economic analysis results indicated that RCA was cost effective only if it was used with a combination of fly ash and Portland cement.

Submitted by Maicon Juliano Schmidt (maicons) on 2015-08-07T11:57:52Z No. of bitstreams: 1 Elenize Ferreira Maciel.pdf: 3841486 bytes, checksum: 9a3420d2d48e3deb4c30dfb972dfe8cc (MD5) / Made available in DSpace on 2015-08-07T11:57:52Z (GMT). No. of bitstreams: 1 Elenize Ferreira Maciel.pdf: 3841486 bytes, checksum: 9a3420d2d48e3deb4c30dfb972dfe8cc (MD5) Previous issue date: 2015-03-25 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / FINEP - Financiadora de Estudos e Projetos / Atualmente a busca por alternativas que minimizem o consumo de matérias-primas e energia e, consequentemente leva à redução de custos, exige estudos voltados para as questões ambientais. Por isso, cada vez mais, pesquisas científicas e tecnológicas estão sendo realizadas visando encontrar maneiras dos resíduos voltarem para o ciclo produtivo e, com isso, reduzirem sua geração e disposição em aterros industriais. Com o advento da industrialização e da variedade de resíduos contendo metais pesados, como o cromo (Cr) presente em solos ou efluentes industriais, estes são estabilizados pela imobilização de seus teores, utilizando-se a técnica de estabilização por solidificação (E/S) em matrizes de concreto. Apesar disso, a forma de tratamento de um resíduo pode causar impactos ambientais negativos, devido ao tipo de resíduo, tecnologia utilizada e seu emprego como novo material a partir do uso combinado do resíduo com a matéria-prima e, até mesmo, com outros tipos de resíduos. Observa-se que as normas brasileiras existentes atualmente para analisar resíduos estão sendo utilizadas para avaliar os produtos provenientes da E/S, onde geralmente simulam situações de disposição final em aterro, somente focando no resíduo, não considerando o real comportamento destes produtos ao longo do seu uso. Neste contexto, o objetivo geral desta pesquisa é avaliar o método Unisinos/Inovatec para a obtenção de extrato lixiviado em produtos estabilizados e solidificados (E/S) com Cr em matriz de concreto de cimento Portland, com vistas ao emprego na avaliação ambiental de materiais e componentes da construção civil. Para isso, foram confeccionados corpos de prova com e sem adição de 2% de óxido de cromo (Cr2O3), os quais foram submetidos a testes de lixiviação por imersão e irrigação. As propriedades do concreto foram avaliadas através dos ensaios de abatimento do tronco de cone, resistência à compressão e porosimetria. A caracterização química das amostras de pasta de cimento foi realizada através de análises de DRX, MEV, ICP-OES e pH. A água deionizada e o ácido utilizados na solução lixiviante, assim como os extratos lixiviados coletados nos tanques dos testes de imersão e irrigação foram analisados por ICP-OES. A partir dos resultados obtidos nos dois testes de lixiviação, por imersão e por irrigação, foi verificado o encapsulamento de 99,99% do Cr no concreto. As duas formas de avaliação da lixiviação de Cr total em monólitos de concreto, durante a fase de uso, apresentaram encapsulamento do Cr no 1º ciclo de lixiviação, o mesmo não sendo mais detectado nos próximos ciclos. A proposta do Método Unisinos/Inovatec para obtenção de extrato lixiviado em concretos com Cr teve a mesma tendência de comportamento observada em estudo com cerâmica vermelha. Entre outros, este fato pode ser considerado como um aspecto positivo para a adoção da proposta do Método, tendo em vista a avaliação ambiental da incorporação de resíduos em componentes de construção civil. / Nowadays the search for alternatives that minimize the consumption of raw materials and energy and thus reduce costs requires studies focused on environmental issues. Therefore, increasingly, scientific research and technology are being conducted to find ways of waste back to the production cycle and thus reduce their generation and disposal in landfills. With the industrialization and the variety of wastes containing heavy metals such as chromium (Cr), present in soil or industrial wastewater, these are stabilized by immobilization of its contents, using a solidification by solidification (S/S) technique in concrete matrix. Nevertheless, the way how the waste is treated can cause negative environmental impacts due to the waste type, technology used and its use as new material from the combined use of the residue with the raw material and even with other waste. It is observed that the existing Brazilian standards today to analyze waste are being used to evaluate the products from the S/S which usually simulate final disposal situations in landfill, only focusing on waste, not considering the actual behavior of these products, over its use. In this context, the aim of this study is to evaluate the Unisinos/Inovatec method for obtaining leached extract stabilized and solidified products (S/S) analyzing the Cr in cement concrete matrix, , overlooking to employment in the environmental assessment of materials and construction components. For this, specimens were prepared with and without addition of 2% chromium oxide (Cr2O3) and were subjected to leaching tests by immersion and irrigation. The concrete properties were evaluated through the Slump test, compressive strength and porosimetry. The chemical characterization of cement paste samples was made through analysis of XRD, SEM, ICP-OES and pH. The deionized water used in the acid leaching solution, and leaching extracts collected in the immersion and irrigation tests were analyzed by ICP-OES. From the results obtained in the two leaching tests, by immersion and irrigation, it was found that 99.99% of Cr was encapsulated. The proposed Unisinos/Inovatec method for obtaining leached extract in concrete with Cr showed the same trend of behavior observed in a study with red ceramic. Among others, this fact can be considered as a positive aspect to the adoption of the proposed method, in view of the environmental assessment of the incorporation of waste in construction components.

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2016-08-16T12:40:11Z No. of bitstreams: 1 Carlos Eduardo Jorge Bernardini.pdf: 1295593 bytes, checksum: f5886fe78f9e706b503e453b2021a91b (MD5) / Made available in DSpace on 2016-08-16T12:40:11Z (GMT). No. of bitstreams: 1 Carlos Eduardo Jorge Bernardini.pdf: 1295593 bytes, checksum: f5886fe78f9e706b503e453b2021a91b (MD5) Previous issue date: 2016-04-27 / The scope of this dissertation consists in analyzing the non-ordinary court protection and its possibility of stabilization regarding preliminary relief and its effects. The work analyses its characters, limitations and possible effects that these kind of decision may have. For this, it is analyzed the concept of court protection, some historical aspects and classification. In light of those concepts, it will be analyzed the non-ordinary court protection types, provision proceedings (preliminary relief), evidence court decision, especially in regards to the New Procedure Civil Code. Furthermore, it will be developed the new ruling concept and some constitutional principles, such as due process of law, the principle of equality and critical Court precedents that encompass the subject matter. In addition, in this chapter cognition techniques will be pointed out and analyzed. We addressed the topic of the unappealeble decisions, historical aspects and classification settling a comparison among CPC/73 and CPC/15. Finally, the preliminary injunction will be analyzed; its proceedings stated in the CPC/15 and some critical aspects / O escopo do presente trabalho é analisar a tutela jurisdicional que concede a antecipação de tutela antecedente, as características, as limitações e os possíveis efeitos que podem ser atribuídos a ela. Com essa finalidade abordaremos, inicialmente, o conceito de tutela jurisdicional, suas classificações segundo a doutrina clássica e também segundo uma perspectiva constitucional. Abordar-se-ão, ainda, no capítulo atinente à tutela jurisdicional, o conceito de tutela jurisdicional diferenciada, alguns exemplos e também, mais especificamente, as tutelas de urgência e da evidência consagradas pelo Novo Código de Processo Civil. Tratar-se-á, outrossim, do conceito de sentença no Novo Código de Processo Civil e de alguns princípios constitucionais julgados importantes e que permeiam a concessão de qualquer tutela jurisdicional, tendo o autor optado por aqueles julgados mais relevantes sobre o assunto, como o princípio do juiz natural, a imparcialidade e a motivação das decisões judiciais. Ainda nesse capítulo, serão examinadas as técnicas de cognição e suas espécies, por constituírem de traço característico da tutela jurisdicional diferenciada, na qual se insere a tutela de urgência. Essa análise é muito importante para se aferir quais os possíveis efeitos que podem ser atribuídos à estabilização da tutela antecipada antecedente. Como não poderia deixar de ser, no capítulo seguinte àquele em que tratada a tutela jurisdicional será abordado o conceito de coisa julgada, sua natureza jurídica, suas características e sua eficácia preclusiva. Nesse capítulo, em específico, serão demonstradas algumas modificações trazidas pelo Novo Código de Processo Civil quanto à coisa julgada e à possível ampliação de seus limites objetivos, face à questão das questões prejudiciais e da ação declaratória incidental. Em seguida, será tratado, de forma sucinta, do que é preclusão, dos aspectos que a diferenciam da coisa julgada e, após isso, da ação rescisória. Atinente à ação rescisória, julgou-se importante saber o seu conceito e cabimento, sobretudo face às alterações que o Novo Código de Processo Civil trouxe em relação ao conceito de sentença, à possibilidade de julgamento antecipado e parcial do mérito e, enfim, aos aspectos e ao alcance da coisa julgada. Finalmente, no último capítulo, pretende-se demonstrar qual a natureza jurídica da tutela antecipada antecedente estabilizada, em face ao que foi abordado no trabalho ─ a finalidade para a qual foi criada, as características e o procedimento para requerimento. Ademais, serão tratados, igualmente, questões controvertidas acerca da nova medida no Código de Processo Civil e possíveis efeitos que podem ser a ela atribuídos. Importante salientar que o trabalho analisou, no que necessário, doutrina e jurisprudência nacionais e internacionais, para relacioná-las com o escopo que se pretende

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2017-10-31T11:52:29Z No. of bitstreams: 1 Mariel Liberato Schwartz.pdf: 1113987 bytes, checksum: 3a33148ee69f1ca00795ddbb306c5724 (MD5) / Made available in DSpace on 2017-10-31T11:52:29Z (GMT). No. of bitstreams: 1 Mariel Liberato Schwartz.pdf: 1113987 bytes, checksum: 3a33148ee69f1ca00795ddbb306c5724 (MD5) Previous issue date: 2017-10-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The critical analysis of the processes of accumulation, concentration and centralization of capital in the Brazilian economy define the core of this Dissertation. It starts from Marx's critical perspective in the context of a supposed expansion of competition in market economies. From this theoretical basis it is possible to return to the understanding of the influence of leading companies in price formation, following the path stressed by Kalecki, as well as to make clear the association between neoliberalism and concentration of capital in the Brazilian economy, with emphasis on some strategic sectors. Within this horizon, the forms of control exercised by corporations over their competitors, supported by their most advanced level of technological dominance, their scale of production and the advantages derived therefrom, limit both the entry of new capital and competition, resulting in centralization of capital in the form of mergers and acquisitions, leading to the narrowing of the capital base involved in the dispute. For Chesnais (1996, 2016), the world oligopoly must be regarded as the general form of contemporary market structures. Since the 1970s the concentration and centralization of the world economy has increased, either in specific forms of reducing competition or through the power of collective monopoly by large economic groups. The internationalization of capital is the process which transforms the production and appropriation of surplus value into a movement realized beyond the original, domestic spaces of capitalist accumulation. The insertion of the Brazilian economy in this world process was accentuated in the 1990s and consolidated in the 2000s: it was a question of accelerating the opening of the economy leading to an increase in the centralization of capital and consequent internationalization of the Brazilian economy, especially through mergers and acquisitions, a historical process of extensive productive reengineering, weakening the participation of the Brazilian State in the mediation and regulation of capitalist accumulation. The central result of the dissertation is to make explicit, with reference to Marx's legacy, the relation between the evolution of the processes of concentration and centralization of capitals in Brazil and a new stage of globalization, allowing to illuminate the rising power of corporations, their power over the determination of prices and on the dynamics of economic policies, inserting the Brazilian case in the changes implied by the recent crisis. If our work of synthesis and conceptual revision serves the eminently pedagogic purpose of alerting clearly and objectively to the risks of the neoliberal orthodoxy, it will have paid, albeit in a preliminary way, to the anguish of a generation that has not given up hope, while facing an unprecedented onslaught of economic and political forces that rule through fear, ignorance and consenting subordination / A revisão teórica, histórica e de indicadores dos processos de acumulação, concentração e centralização de capital na economia brasileira a partir da mundialização nos anos 90 constitui o cerne desta Dissertação. Trata-se de recuperar a perspectiva aberta por Marx no contexto de uma suposta ampliação da concorrência em economias de mercado, especialmente na periferia capitalista. A partir dessa perspectiva teórica e histórica é possível retomar o entendimento da influência das empresas líderes na formação de preços, seguindo a trilha apontada por Kalecki, assim como deixar clara a associação entre neoliberalismo e concentração de capitais na economia brasileira, com destaque para alguns setores estratégicos após a estabilização de preços (Plano Real). Ganham relevância as formas captura da política econômica assim como os mecanismos de controle que as corporações impõem aos concorrentes, amparadas em seu nível mais avançado de domínio tecnológico, na sua escala de produção e nas vantagens que daí derivam, dificultando a entrada de capitais ou acirrando a rivalidade com os concorrentes, resultando em centralização de capital na forma de fusões e aquisições, levando ao estreitamento da base de capitais envolvidos na disputa. A perspectiva histórica, amparada pela obra de Chesnais, ressalta o oligopólio mundial como a forma geral das estruturas contemporâneas de mercado. Desde os anos 1970 a concentração e centralização da economia mundial são elevadas, seja na forma específica de limitação à competição, seja via poder de monopólio dos grandes grupos econômicos. A internacionalização do capital é um processo em que a produção e a apropriação de mais-valia são realizadas para além dos espaços de origem dos capitalistas. A inserção da economia brasileira nesse processo de mundialização acentua-se na década de 1990 e se consolida nos anos 2000: tratou-se de acelerar a abertura da economia e fomentar a centralização de capital, processo histórico de ampla reengenharia produtiva, fragilizando a participação do Estado brasileiro na mediação de conflitos e direcionamento do ajuste produtivo. O resultado central da dissertação é explicitar, tendo como referência o legado de Marx, a relação entre a evolução dos processos de concentração e centralização de capitais no Brasil e uma nova etapa da mundialização, permitindo iluminar o processo de ampliação do poder das corporações, inclusive na determinação de preços e na dinâmica da política econômica, inserindo o caso brasileiro nas mudanças implicadas pela crise recente. Se este nosso trabalho de síntese e revisão conceitual servir ao propósito eminentemente didático de alertar com clareza e objetividade para os riscos da ortodoxia doutrinária liberal já terá atendido, ainda que de modo preliminar, à angústia de uma geração que não perdeu a esperança, mas se depara com uma ofensiva sem precedentes das forças econômicas e políticas que imperam através do medo, da ignorância e da subordinação consentida

O presente trabalho examina as políticas econômicas adotadas pelo Brasil como medidas de enfrentamento à crise econômica mundial iniciada em 2007-2008. Para isso, apresenta-se a conceituação de crise econômica e suas flutuações, além de um breve histórico de crises econômicas em alguns países em determinados períodos. Em sequência, é apresentada a definição de política econômica, com ênfase na política fiscal e na política monetária e creditícia, bem como seus instrumentos de estabilização ou precaução às crises. Após essa etapa, o trabalho registra os principais efeitos da crise econômica no mundo, expondo os principais indicadores e os principais efeitos da crise econômica no Brasil. Para cumprir sua proposta, explora as principais medidas de políticas econômicas adotadas no Brasil como forma de conter a crise mundialmente instaurada. Os procedimentos metodológicos utilizados são: revisão bibliográfica e pesquisa empírica de dados secundários para apresentação da crise internacional; pesquisa teórica e empírica secundária sobre as medidas econômicas adotadas pelo Brasil e a análise do conteúdo apurado, estabelecendo a avaliação baseada no respectivo levantamento bibliográfico. / This paper examines the economic policies adopted by Brazil as measures to fight the global economic crisis that began in 2007-2008. In order to accomplish that, the concept of economic crisis and its fluctuations is presented, as well as a brief history of economic crises in s few countries over certain times. Then, the definition of economic policy, with an emphasis on tax policy and monetary and credit policy, highlighting their stabilization instruments or measures of precaution against crises are presented. After this step, the research reports the main effects of the economic crisis in the world economy, exposing the key indicators and the main effects of the economic crisis in Brazil. To fulfill its main proposal, the study explores the key measures of economic policies adopted in Brazil as a way to stem the worldwide crisis. The methodological procedures used are: literature review and empirical research of secondary data to present the international crisis; theoretical and secondary empirical research on economic measures adopted by Brazil, and the analysis of the discussed points, developing an assessment based on the respective literature.

Cette thèse est consacrée à l'étude de problèmes de stabilisation exponentielle par retour d'état ou "feedback" des équations de Navier-Stokes dans un domaine borné Ω ⊂ Rd, d = 2 ou 3. Le cas d'un contrôle localisé sur la frontière du domaine est considéré. Le contrôle s'exprime en fonction du champ de vitesse à l'aide d'une loi de feedback non-linéaire. Celle-ci est fournie grâce aux techniques d'estimation a priori via la procédure de Faedo-Galerkin laquelle consiste à construire une suite de solutions approchées en utilisant une base de Galerkin adéquate. Cette loi de feedback assure la décroissance exponentielle de l'énergie du problème discret correspondant et grâce au résultat de compacité, nous passons à la limite dans le système satisfait par les solutions approchées. Le chapitre 1 étudie le problème de stabilisation des équations de Navier- Stokes autour d'un état stationnaire donné, tandis que le chapitre 2 examine le problème de stabilisation autour d'un état non-stationnaire prescrit. Le chapitre 3 est consacré à l'étude de la stabilisation du problème de Navier-Stokes avec des conditions aux bords mixtes (Dirichlet- Neumann) autour d'un état d'équilibre donné. Enfin, nous présentons dans le chapitre 4, des résultats numériques dans le cas d'un écoulement autour d'un obstacle circulaire / In this thesis we study the exponential stabilization of the two and three-dimensional Navier- Stokes equations in a bounded domain Ω, by means of a boundary control. The Control is expressed in terms of the velocity field by using a non-linear feedback law. In order to determine a feedback law, we consider an extended system coupling the Navier-Stokes equations with an equation satisfied by the control on the domain boundary. While most traditional approaches apply a feedback controller via an algebraic Riccati equation, the Stokes-Oseen operator or extension operators, a Galerkin method is proposed instead in this study. The Galerkin method permits to construct a stabilizing boundary control and by using energy a priori estimation technics, the exponential decay is obtained. A compactness result then allows us to pass to the limit in the nonlinear system satisfied by the approximated solutions. Chapter 1 deals with the stabilization problem of the Navier-Stokes equations around a given steady state, while Chapter 2 examines the stabilization problem around a prescribed non-stationary state. Chapter 3 is devoted to the stabilization of the Navier-Stokes problem with mixed-boundary conditions (Dirichlet-Neumann), around to a given steady-state. Finally, we present in Chapter 4, numerical results in the case of a flow around a circular obstacle

Ce travail est basé sur l’étude expérimentale, étape par étape, du procédé de lyophilisation, afin de comprendre les impacts des différents paramètres du procédé sur la viabilité d’une souche modèle probiotique de type lactobacillus casei. Nous avons tout d’abord étudié les propriétés thermodynamiques des formulations considérées à base de lactose et de polyvinylpyrrolidone, (PVP) en commençant dans un premier temps par l’obtention du diagramme d’état du système amorphe constitué du binaire eau-PVP, puis le diagramme de fusion du ternaire eau-PVP-lactose afin d’en déduire les paramètres clefs pour l’optimisation des cycles de lyophilisation de ces suspensions bactériennes. Dans la deuxième partie, nous avons caractérisé par microscopie électronique à balayage (MEB) la localisation des bactéries au sein de la phase solide amorphe des lyophilisats poreux. Ensuite, les différentes formulations ont été soumises à différents protocoles de congélation (vitesse de refroidissement ; recuit) afin d’obtenir les meilleurs résultats en termes de taux de survie des bactéries. Avec la formulation sélectionnée précédemment nous nous sommes intéressés à l’influence des paramètres opératoires de sublimation (température étagère et pression totale de sublimation) conduisant aux meilleurs taux de survie des bactéries. Nous avons observé que nos cellules probiotiques, avec ces formulations, pouvaient être lyophilisées, au-dessus de la température limite de collapse, sans impacter la viabilité des cellules présentes ou insérées au sein de la phase matrice poreuse du lyophilisat final, ce dernier présentant de plus, de bonnes propriétés d’usage en termes de stabilité en vue d’une mise en forme galénique ou d’un stockage ultérieur / This work is based on the experimental study, step by step, of the freeze-drying process of a model probiotic strain of lactobacillus caseï type to understand the impact of the numerous factors (formulation; freezing protocol; operating conditions) on the survival rates of these bacteria in the final lyophilisate. Firstly, we investigated the thermo-dynamical and physical properties (vitreous transition and melting temperatures) of formulations based on lactose and polyvinylpyrrolidone (PVP) protectants and their mixture. Thus, we have determined the phase diagrams and the melting diagram of the water+PVP binary system and of the ternary water-PVP-lactose system. Next, we determined the optimal freezing protocol (freezing rates; annealing treatment) with different formulations which led to the best survival rates. Next, in a preliminary study we have characterized by SEM (scanning electron microscopy) the location of the cells inserted inside the solid amorphous phase of the porous matrix of the different lyophilisates. Secondly, with the pre-selected formulation, we experienced the influence of the main operating sublimation parameters (shelf temperature and total gas pressure), leading to highest product quality in terms of bacteria survival ratios of the final lyophilisates. We observed that these probiotics cells, with this formulation, could be freeze-dried above the limit collapse temperature without impacting significantly the viability of the freeze-dried cells and with lyophilisates of high stability attributes

Les travaux présentés dans cette thèse s'inscrivent dans le cadre de la chaire OXYTEC qui regroupe l'entreprise Air Liquide, CentraleSupélec et le CNRS. Ce travail bénéficie également de l'appui de l'ANR. Ce manuscrit fait état des premiers développements et résultats sur le plan expérimental. Un dispositif complet a été développé au laboratoire EM2C pour étudier l'oxy-combustion de flammes stabilisées sur un injecteur tourbillonneur jusqu'à des pressions de 30 bar. Les résultats présentés dans cette thèse ont traits à des prémélanges dont le combustible est du méthane lorsque le foyer opère à pression atmosphérique. Les techniques de LIF-OH, la PIV, la LDV complétées par des mesures de chimiluminescence et de température sont utilisées (1) pour accumuler des données sur la structure de trois flammes de référence CH4/air, CH4/O2/N2 et CH4/O2/CO2 qui sont utilisées pour valider des outils de simulation de la combustion et des transferts thermiques, (2) élucider les mécanismes de stabilisation des oxy-flammes swirlés pré-mélangées à partir d'études paramétriques sur le nombre de swirl, la vitesse débitante, la vitesse laminaire de flamme et l'angle de l'ouvreau de l'injecteur, et (3) comparer la structure des oxy-flammes diluées au CO2 avec des flammes CH4/air en examinant notamment la position de pied de flamme, la topologie générale de la flamme et les températures des parois du foyer. / The work presented in this thesis falls within the framework of the OXYTEC chair, a partnership between Air Liquide, CentraleSupélec and the CNRS. This work also benefits from the support of the ANR. This manuscript reports the first developments and results on the experimental level. A test rig has been developed to study oxy-combustion of swirl-stabilized flames up to pressures of 30 bar. The results presented deal with premixed conditions where the fuel is methaneand the setup is operated at atmospheric pressure. Laser induced fluorescence on the hydroxyl radical, particle imaging velocimetry, Doppler laser velocimetry completed by chemiluminescence imaging and temperature measurements are used to (1) gather data on the structure of three reference flames CH4/air, CH4/O2/N2 and CH4/O2/CO2 which are used to validate simulations of the reacting flow and heat transfer and (2) elucidate the stabilization mechanisms of premixed swirling oxy-flames from parametric studies by varying the swirl number, the bulk injection velocity, the laminar burning velocity and the injector cup angle and (3) compare the structure of CO2 diluted oxy-flames with CH4/air flames by examining the position of the flame leading edge, the general topology of the flame and the temperatures of flow and the combustor walls.