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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Contribuição para proteção de distância em linhas compensadas com dispositivos UPFC

Rodríguez Paz, Martín Cruz January 2015 (has links)
Dispositivos baseados em eletrônica de potência, conhecidos na literatura como Dispositivos FACTS (Flexible AC Transmission Systems) permitem aumentar a capacidade de transmissão diminuindo a margem de segurança necessária para uma operação segura do sistema elétrico de potência (SEP) sem construir novas linhas, permitindo controlar os fluxos nas linhas e assim permitindo que os contratos entre as empresas de transmissão sejam respeitados. Entre os dispositivos FACTS, o de maior versatilidade é o Unified Power Flow Controller (UPFC), capaz de controlar três variáveis do sistema. No entanto, a inclusão desses dispositivos traz outros problemas ao SEP, um deles, a proteção das linhas. Este trabalho apresenta uma contribuição para uma nova formulação matemática, adaptativa e compensada para a proteção de distância baseada na impedância aparente para a proteção de linhas compensadas com dispositivos UPFC. A formulação proposta se baseia em uma modelagem trifásica do sistema e na compensação da impedância aparente calculada através dos parâmetros controlados do UPFC e da estimação da impedância da falta. Resultados obtidos através da simulação exaustiva de faltas, mostram que esta formulação apresenta um excelente desempenho para a proteção de distância de linhas compensadas por dispositivos UPFC. / Power electronics-based devices, known as FACTS devices (Flexible Alternating current Transmission Systems) allow to increase transmission capacity by decreasing the safety margin required for a secure operation of the Electric Power System (EPS). It is possible without need to build new lines, allowing to control the flows in lines and thus allowing contracts between the transmission companies are respected. Among the FACTS devices, the most versatile is the Unified Power Flow Controller (UPFC) capable of controlling three variables of the system. However, the inclusion of these devices brings other problems to the EPS, one of them, the transmission lines protection. This Thesis presents a contribution to a new mathematical formulation, adaptive and compensated for the distance protection based on the apparent impedance to protect transmission lines compensated by UPFC devices. The proposed formulation is based on a three-phase frame reference and the compensation of apparent impedance by the UPFC controlled parameters and the estimation of the fault impedance. Results obtained, through the comprehensive simulation of faults, show that it formulation present excellent performance for distance protection of transmission lines compensated by UPFC devices.
232

Modélisation et commande robuste des systèmes biologiques : exemple de la production d’acide lactique en fermenteur industriel / Modeling and robust control of biological systems : example of lactic acid production in industrial fermenter

Gonzalez, Karen Vanessa 25 September 2015 (has links)
Cette thèse de doctorat porte sur l’optimisation du bioprocédé de production d’acide lactique à partir de la farine de blé. L'acide lactique s’avère en effet de plus en plus attractif pour la production de PLA (acide poly lactique), un bio polymère, d’autant plus que différentes matières premières peu coûteuses comme la farine de blé sont désormais utilisées comme sources de carbone pour sa production. Cette thèse comprend trois parties principales. Une première partie propose pour l’optimisation du procédé de transformation du blé un schéma innovant composé de trois étapes successives : une liquéfaction, suivi d’une étape de saccharification et hydrolyse des protéines simultanées (SSPH) et une étape finale de saccharification, hydrolyse des protéines et fermentation simultanées (SSPHF). La deuxième partie s’intéresse à la modélisation de l’étape SSPHF (étape limitante) dans un bioréacteur continu. La détermination des paramètres du modèle ainsi que leur validation sont réalisées à l’aide de campagnes d’essais sur un bioréacteur de 5 L.Enfin, la dernière partie développe la mise en oeuvre de stratégies de commande permettant de maintenir le bioprocédé à son point optimal de fonctionnement. Pour ce faire, du fait de l’absence de capteurs pour la mesure en temps réel des concentrations des variables clé dans le bioréacteur, des estimateurs de ces concentrations ainsi que du taux de production en acide lactique sont tout d’abord élaborés. Des stratégies de commande régulant la concentration d’acide lactique à sa valeur optimale sont ensuite synthétisées et comparées en simulation. Une commande adaptative combinant une commande linéarisante par retour d’état et un estimateur du taux de production en acide lactique est finalement retenue et validée expérimentalement sur un réacteur instrumenté. Cette dernière s’est avérée robuste vis-à-vis des erreurs de modélisation et a permis lors des expériences de doubler la productivité de l’acide lactique. / This PhD thesis focuses on the optimization of the bioprocess of lactic acid production from wheat flour. Indeed, lactic acid has received much attention for the production of PLA (Poly Lactic Acid), a biopolymer, since different inexpensive raw material such as wheat flour are now used as carbon source for its production. This work was performed in three main steps. In the first step, an innovative wheat transformation process is proposed, whose main steps are the following: a liquefaction followed by a simultaneous saccharification, proteins hydrolysis (SSPH) and and a final simultaneous saccharification, proteins hydrolysis and fermentation (SSPHF). Secondly, the modeling of the SSPHF (limiting step) in a continuous bioreactor is considered. The determination and validation of model parameters is performed by means of experimental campaigns in a 5 L bioreactor.In the last step, the development of control strategies to maintain the process at its optimal operating point is considered. To do so, due to the absence of sensors for real-time measurement of the concentrations of key variables of the bioreactor, estimators of these concentrations and of the lactic acid production rate are first developed. Then, control strategies for regulating the lactic acid concentration at its optimal value are designed and compared in simulation. An adaptive control combining a state feedback linearizing control and an estimator of the lactic acid production rate is finally chosen to be experimentally validated on an instrumented reactor. This strategy showed good robustness features with respect to modeling mismatches and was able during experiments to increase twice the lactic acid productivity.
233

Adaptive control of deterministic and stochastic approximation errors in simulations of compressible flow / Contrôle adaptatif des erreurs d'approximation stochastique et déterministe dans la simulation des écoulements compressible

Van Langenhove, Jan Willem 25 October 2017 (has links)
La simulation de systèmes d'ingénierie non linéaire complexes tels que les écoulements de fluide compressibles peut être ciblée pour rendre plus efficace et précise l'approximation d'une quantité spécifique (scalaire) d'intérêt du système. En mettant de côté l'erreur de modélisation et l'incertitude paramétrique, on peut y parvenir en combinant des estimations d'erreurs axées sur des objectifs et des raffinements adaptatifs de maillage spatial anisotrope. A cette fin, un cadre élégant et efficace est celui de l'adaptation dite basé-métrique où une estimation d'erreur a priori est utilisée comme indicateur d’adaptation de maillage. Dans cette thèse on propose une nouvelle extension de cette approche au cas des approximations de système portant une composante stochastique. Dans ce cas, un problème d'optimisation est formulé et résolu pour un meilleur contrôle des sources d'erreurs. Ce problème est posé dans le cadre continu de l'espace de métrique riemannien. Des développements algorithmiques sont également proposés afin de déterminer les sources dominates d’erreur et effectuer l’adaptation dans les espaces physique ou des paramètres incertains. L’approche proposé est testée sur divers problèmes comprenant une entrée de scramjet supersonique soumise à des incertitudes paramétriques géométriques et opérationnelles. Il est démontré que cette approche est capable de bien capturé les singularités dans l’escape stochastique, tout en équilibrant le budget de calcul et les raffinements de maillage dans les deux espaces. / The simulation of complex nonlinear engineering systems such as compressible fluid flows may be targeted to make more efficient and accurate the approximation of a specific (scalar) quantity of interest of the system. Putting aside modeling error and parametric uncertainty, this may be achieved by combining goal-oriented error estimates and adaptive anisotropic spatial mesh refinements. To this end, an elegant and efficient framework is the one of (Riemannian) metric-based adaptation where a goal-based a priori error estimation is used as indicator for adaptivity. This thesis proposes a novel extension of this approach to the case of aforementioned system approximations bearing a stochastic component. In this case, an optimisation problem leading to the best control of the distinct sources of errors is formulated in the continuous framework of the Riemannian metric space. Algorithmic developments are also presented in order to quantify and adaptively adjust the error components in the deterministic and stochastic approximation spaces. The capability of the proposed method is tested on various problems including a supersonic scramjet inlet subject to geometrical and operational parametric uncertainties. It is demonstrated to accurately capture discontinuous features of stochastic compressible flows impacting pressure-related quantities of interest, while balancing computational budget and refinements in both spaces.
234

Contribuição para proteção de distância em linhas compensadas com dispositivos UPFC

Rodríguez Paz, Martín Cruz January 2015 (has links)
Dispositivos baseados em eletrônica de potência, conhecidos na literatura como Dispositivos FACTS (Flexible AC Transmission Systems) permitem aumentar a capacidade de transmissão diminuindo a margem de segurança necessária para uma operação segura do sistema elétrico de potência (SEP) sem construir novas linhas, permitindo controlar os fluxos nas linhas e assim permitindo que os contratos entre as empresas de transmissão sejam respeitados. Entre os dispositivos FACTS, o de maior versatilidade é o Unified Power Flow Controller (UPFC), capaz de controlar três variáveis do sistema. No entanto, a inclusão desses dispositivos traz outros problemas ao SEP, um deles, a proteção das linhas. Este trabalho apresenta uma contribuição para uma nova formulação matemática, adaptativa e compensada para a proteção de distância baseada na impedância aparente para a proteção de linhas compensadas com dispositivos UPFC. A formulação proposta se baseia em uma modelagem trifásica do sistema e na compensação da impedância aparente calculada através dos parâmetros controlados do UPFC e da estimação da impedância da falta. Resultados obtidos através da simulação exaustiva de faltas, mostram que esta formulação apresenta um excelente desempenho para a proteção de distância de linhas compensadas por dispositivos UPFC. / Power electronics-based devices, known as FACTS devices (Flexible Alternating current Transmission Systems) allow to increase transmission capacity by decreasing the safety margin required for a secure operation of the Electric Power System (EPS). It is possible without need to build new lines, allowing to control the flows in lines and thus allowing contracts between the transmission companies are respected. Among the FACTS devices, the most versatile is the Unified Power Flow Controller (UPFC) capable of controlling three variables of the system. However, the inclusion of these devices brings other problems to the EPS, one of them, the transmission lines protection. This Thesis presents a contribution to a new mathematical formulation, adaptive and compensated for the distance protection based on the apparent impedance to protect transmission lines compensated by UPFC devices. The proposed formulation is based on a three-phase frame reference and the compensation of apparent impedance by the UPFC controlled parameters and the estimation of the fault impedance. Results obtained, through the comprehensive simulation of faults, show that it formulation present excellent performance for distance protection of transmission lines compensated by UPFC devices.
235

Avaliação e desenvolvimento de algoritmos de controle aplicado a um processo extrativo de fermentação alcoolica continua / Development and evaluating the performance of predictive and adaptative controllers applied to an extractive fermentative process

Duarte, Elis Regina 14 August 2007 (has links)
Orientadores: Rubens Maciel Filho, Laercio Ender / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-08T18:03:43Z (GMT). No. of bitstreams: 1 Duarte_ElisRegina_D.pdf: 5707651 bytes, checksum: d1348f1129ff1981af5a94400a0f9040 (MD5) Previous issue date: 2007 / Resumo:0 objetivo deste trabalho foi desenvolver e avaliar diferentes algoritmos de controle para o processo extrativo de fermentação alcoólica contínua. Para isto foram comparados controladores do tipo preditivo e adaptativo. Para o controle preditivo, foi avaliado o Controle por Matriz Dinâmica (DMC) e foi desenvolvido um algoritmo de controle preditivo baseado em modelo usando redes neurais artificiais (MPC Neural) com aprendizagem em tempo real das redes. Para o controle adaptativo, foi proposto o aperfeiçoamento do algoritmo de controle CONDEG (Controle Neural Direto Baseado no Erro Global) Modificado, desenvolvido por Duarte (2004), O algoritmo está baseado em redes neurais artificiais, com aprendizagem em tempo real, de acordo com as alterações que ocorrem no processo. Os parâmetros de penalização das ações de controle, que são parâmetros de projeto do controlador, foram ajustados ao longo do tempo através da aplicação de um algoritmo do Filtro de Kalman. Para o procedimento de investigação foi utilizada a simulação computacional para o qual todos os algoritmos de controle estudados foram implementados em linguagem de programação Fortran 90 e aplicados a um processo extrativo de fermentação alcoólica contínua para produção de etanol desenvolvido por Silva (1999). O modelo matemático utilizado foi desenvolvido por Costa et al(2001). As simulações em malha fechada realizadas utilizando os algoritmos propostos mostraram melhores resultados para os algoritmos de controle usando redes com aprendizagem ao longo do tempo e que o algoritmo de controle CONDEG Modificado usando filtro de Kalman com fator de velocidade associado foi eficiente e robusto, pois apresentou bons resultados em problemas dos tipos servos e regulador. / Abstract: The objective of the present work is to develop and to evaluate the performance of predictive and adaptive controllers, applied to an extractive fermentative process. As predictive controllers the Dynamical Matrix Control (DMC) and a model predictive control based on artificial neural networks with on-line learning were considered. The adaptive controller is an improvement of the Modified Condeg strategy control (Direct Neural Control based on Global Error), developed by Duarte (2004). The strategy is based on artificial neural networks, with on-line learning, according to modifications that occur in the process. The control actions penalization parameters, that are in fact controller design parameters, are on-line adjusted through an algorithm based on Kalman filter. The performance evaluation was carried out through computer simulation with all algorithms implemented in Fortran 90,.As a case study, an extractive fermentation alcoholic process developed by Silva (1999) was taken into account with the mathematical model developed by Costa et. al (2001). The results obtained from closed-loop simulations using the proposed algorithms showed better results for the neural networks with on-line learning. The Modified Condeg wsth Kalman Filter plus velocity factor is efficient and robust for servo and regulatory applications. / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química
236

Diagnóstico adaptativo familiar: um estudo piloto / Adaptive family diagnosis: a pilot study

Janaina Coniaric 10 August 2011 (has links)
A Psicologia Clínica Preventiva vem se desenvolvendo no campo da pesquisa e prática, com o intuito de aprimorar modelos de intervenção clínica que possibilitem a promoção de saúde e a prevenção de problemas psíquicos na comunidade. O atendimento preventivo familiar é um meio de se alcançar a comunidade. Em projetos psicossociais com famílias, constatou-se a necessidade de um instrumento diagnóstico familiar que abrangesse a detecção precoce de sinais e sintomas, abreviando uma ação mais eficaz. Perante essa demanda, o presente trabalho teve por objetivo geral: o estudo piloto de um modelo diagnóstico familiar, com base na concepção da Teoria da Adaptação e da Escala Diagnóstica Adaptativa Operacionalizada (EDAO), para utilização no campo da Prevenção em Psicologia Clínica; e por objetivos específicos: 1) avaliar a adequação das relações familiares nos setores adaptativos; 2) verificar as situações-problema intrafamiliares; e, 3) averiguar quantas entrevistas preventivas são suficientes para abarcar a compreensão psicodinâmica/adaptativa da família. Para tanto, foram realizadas entrevistas preventivas domiciliares com cinco famílias inscritas no Programa de Saúde da Família (PSF). Verificou-se que três a quatro entrevistas preventivas, com duração de uma hora e meia, foram suficientes para obter os dados dos setores adaptativos e definir as situações-problema intrafamiliares. Os principais fatores que influenciaram na duração das entrevistas foram: indicação de brevidade, motivação de cada família, interrupções, capacidade da família em abordar assuntos ansiógenos, a superação ou não de resistências e, a participação de vários membros familiares. Uma das famílias interrompeu sua participação, mas seus dados puderam ser considerados na análise de resultados. A avaliação da adequação setorial indicou que: nenhuma família apresentou respostas adequadas no setor Afetivorelacional, somente, uma apresentou pouco adequada e, a maioria apresentou pouquíssimo adequadas; no setor Produtividade: duas famílias apresentaram respostas adequadas, duas apresentaram pouco adequadas e, uma pouquíssimo adequadas; no Orgânico duas famílias apresentaram respostas adequadas, uma pouco adequadas e duas pouquíssimo adequadas; já no Sociocultural todas as famílias apresentaram respostas adequadas. As situações-problemas foram passíveis de definição e, eram desencadeadas predominantemente por conflitos no setor Afetivo-relacional. Estes dados revelaram maior comprometimento no setor Afetivorelacional com influência no setor Orgânico. Assim, o estudo mostrou que este modelo de diagnóstico é uma proposta possível no que tange ao trabalho preventivo com famílias. Entende-se que a importância deste estudo, recai na possibilidade de promover recursos teóricos e técnicos que inspirem trabalho clínico e preventivo com famílias / Preventive Clinical Psychology has been developing in the research and practical fields with a view to improving clinical intervention models to enable health promotion and psychicproblem prevention in the community. Preventive family assistance is understood as tool to reach the community. In psychosocial projects involving families, the author found the need for a family diagnosis tool to cover the early detection of signs and symptoms, therefore accelerating a more effective action. In view of such demand, the general purpose of this paper is: to develop a pilot study for a family diagnosis model, based on the concept of the Adaptation Theory and Operational Adaptive Diagnostic Scale (EDAO, in Portuguese) to be used in the field of Clinical Psychology Prevention; its specific purposes were: 1) to evaluate the adequacy of family relations in the adaptive areas; 2) to check intra-family problem situations; and 3) to investigate how many preventive interviews are sufficient to cover the psychodynamic/adaptive understanding of the family. For this reason, preventive home interviews were be conducted with five families registered with the Family Health Program (PSF, in Portuguese). We observed that three to four one-hour-and-a-half preventive interviews were sufficient to obtain data from adaptive areas and define intra-family problem situations. The main factors affecting the duration of interviews were: indication of brevity, motivation of each family, interruptions, family ability to address anxiogenic matters, overcoming or not resistance, and participation of several family members. One of the families discontinued participation, but their data could be considered in the results analysis. The evaluation of area adequacy suggested that: none of the families presented proper responses in the affection-relational area, only one of them presented a poor response, most of them presented very poor response; in the productivity area: two families presented proper responses, two presented poor response and one of them presented very poor responses; in the organic area, two families presented proper responses, one of them presented poor responses and two of them presented very poor responses; however, in the social-cultural area, all families presented proper responses. Problem situations were possible to define and were triggered predominantly by conflicts in the affection-relational area. Those data revealed greater commitment in the affection-relational area with influence on the organic area. Therefore, the study showed that this diagnosis model is a viable proposal in regard to preventive work with families. The importance of this study is understood to be related to the possibility of promoting theoretical and technical courses to make feasible a clinical and preventive work with families
237

Adictos a drogas em tratamento: um estudo sobre o funcionamento psíquico de suas mães / Drug addicts in treatment: a study on the psychological functioning of their mothers

Aline Esteves Basaglia 11 May 2010 (has links)
Nos pressupostos winnicotianos, experiências provenientes de uma maternagem insatisfatória podem não propiciaro desenvolvimento adequado dos fenômenos tradicionais, resultando em patologias como a adicção. Devido aos poucos estudos existentes relacionando o fenômeno adicção com a maternagem, decidiu-se investigar o funcionamento psíquico de mães de adictos a drogas, a fim de se verificar quais características deste funcionamento poderiam dificultar o desempenho adequado da função materna. Fizeram parte deste estudo 10 mães de adictos a drogas (cocaína), que foram atendidas individualmente em situação de psicodiagnóstico, incluindo Entrevista semidirigida sobre o filho, Entrevista baseada na Escala Diagnóstica Adaptativa Operacionalizada (EDAO) sobre elas próprias e aplicação do Método de Rorschach. As mães foram convidadas a participar desta pesquisa à medida que seus filhos - do sexo masculino e adicto à droga cocaína - davam entrada para tratamento no Centro de Atenção Psicossocial em Álcool e Droga (CAPS-AD) do município de Santana de Parnaíba (região oeste da Grande São Paulo, Brasil). Os filhos adictos não apresentavam perturbação neurológica ou psicológica grave e foram avaliados por outro profissional diferente do resposnável por esta coleta de dados. Na região atendida, predomina uma população de baixa renda. Os dados foram analisados e relacionados entre si, privilegiando os processos de pensamento, de socialização e a dinâmica afetiva, utilizando-se o referencial psicanalítico winnicottiano. Os resultados do grupo no Método de Rorschach e nas Entrevistas configuraram um perfil marcado por um funcionamento psíquico imaturo, por um embotamento afetivo e intelectual, dificuldades de relacionamento objetal adulto, atitudes ambíguas e tendência à repetição de vivências conjugais geradoras de sofrimento, decorrentes de violência e abusos. Tal funcionamento parece derivar-se das próprias vivências precoces, permeadas por uma maternagem não suficientemente boa, que compromete o desenvolvimento do processo de sepração e individuação. A partir deste funcionamento, estas mães não se mostraram capazes de favorecer o desenvolvimento adequado de seus filhos pelas próprias dificuldades na passagem da dependência para a independência e no desenvolvimento de um espaço transicional. / Winnicott reported that an unsatisfatory good-enough mothering experience may not provide the appropriate transitional phenomena development leading to pathologies, for instance the addition. Considering the few studies regarding the relations between the addictive phenomenon and mothering from the mother perspective, was decided upon the investigation on the drug-addicted mother\'s psychic functioning, in order to verify if these performance characteristics could disturb the proper mother\'s function development. This study copes with 10 drug-addict mothers (cocain) that were attended individually in psychodiagnostic assessment, including a semi-structured interview referring to their son, an Adaptive Operational Diagnostic Scale (EDAO) interview and the Rorschach Method. The mothers were invited to participate in the study as long as that their sons, also drug addicted (cocain), had been brought for the treatment at the Alcohool and Drugs Psychological Care Center (CAPS-AD) in the Santana de Parnaíba municipality (São Paulo west region, Brazil), and this is predominantly low-income population. Theis sons were addicts and they did not present neurological or psychological severe disturbance, they were evaluated by another professional other than the person responsible for data collection. Using the Winnicott\'s psychoanalitic reference the data was analyzed and related among each other, focusing on the thought and socialization processes, and on the affective dynamics. The Rorschach Method and interviews results suggested a group with an immature psychological functioning profile, distinguished by an affective flattening, an intellectual blunting, a difficulty in an adult object-reaction, double-meaning attitudes and repeated marital experiences that causes suffering by its violence and abuse. These characterists seem to be a consequence of their own previous experiences and from an unsatisfactory good-enough mothering, hindering their separation/individuation process development. Consequently, the mothers were not able to assist their sons with a proper development considering their own difficulties related to the dependence-independence process and their transitional area development.
238

Resolução numérica de equações de advecção-difusão empregando malhas adaptativas / Numerical solution of advection-diusion equations using adaptative mesh renement

Alexandre Garcia de Oliveira 07 July 2015 (has links)
Este trabalho apresenta um estudo sobre a solução numérica da equação geral de advecção-difusão usando uma metodologia numérica conservativa. Para a discretização espacial, é usado o Método de Volumes Finitos devido à natureza conservativa da equação em questão. O método é configurado de modo a ter suas variáveis centradas em centro de célula e, para as variáveis, como a velocidade, centradas nas faces um método de interpolação de segunda ordem é utilizado para um ajuste numérico ao centro. Embora a implementação computacional tenha sido feita de forma paramétrica de maneira a acomodar outros esquemas numéricos, a discretização temporal dá ênfase ao Método de Crank-Nicolson. Tal método numérico, sendo ele implícito, dá origem a um sistema linear de equações que, aqui, é resolvido empregando-se o Método Multigrid-Multinível. A corretude do código implementado é verificada a partir de testes por soluções manufaturadas, de modo a checar se a ordem de convergência prevista em teoria é alcançada pelos métodos numéricos. Um jato laminar é simulado, com o acoplamento entre a equação de Navier-Stokes e a equação geral de advecção-difusão, em um domínio computacional tridimensional. O jato é uma forma de vericar se o algoritmo de geração de malhas adaptativas funciona corretamente. O módulo produzido neste trabalho é baseado no código computacional AMR3D-P desenvolvido pelos grupos de pesquisa do IME-USP e o MFLab/FEMEC-UFU (Laboratório de Dinâmica de Fluidos da Universidade Federal de Uberlândia). A linguagem FORTRAN é utilizada para o desenvolvimento da metodologia numérica e as simulações foram executadas nos computadores do LabMAP(Laboratório da Matemática Aplicada do IME-USP) e do MFLab/FEMEC-UFU. / This work presents a study about the numerical solution of variable coecients advectiondi usion equation, or simply, general advection-diusion equation using a conservative numerical methodology. The Finite Volume Method is choosen as discretisation of the spatial domain because the conservative nature of the focused equation. This method is set up to have the scalar variable in a cell centered scheme and the vector quantities, such velocity, are face centered and they need a second order interpolation to get adjusted to the cell center. The computational code is parametric, in which, any implicit temporal discretisation can be choosen, but the emphasis relies on Crank-Nicolson method, a well-known second order method. The implicit nature of aforementioned method gives a linear system of equations which is solved here by the Multilevel-Multigrid method. The correctness of the computational code is checked by manufactured solution method used to inspect if the theoretical order of convergence is attained by the numerical methods. A laminar jet is simulated, coupling the Navier-Stokes equation and the general advection-diusion equation in a 3D computational domain. The jet is a good way to check the corectness of adaptative mesh renement algorithm. The module designed here is based in a previous implemented code AMR3D-P designed by IME-USP and MFLab/FEMEC-UFU (Fluid Dynamics Laboratory, Federal University of Uberlândia). The programming language used is FORTRAN and the simulations were run in LabMAP(Applied Mathematics Laboratoy at IME-USP) and MFLab/FEMEC-UFU computers.
239

Développement d'un microscope bi-photon à front d'onde optimisé pour l'imagerie calcique profonde dans le cerveau de souris / Development of a wavefront optimized two-photon microscope for deep calcium imaging in the mouse brain

Champelovier, Dorian 01 December 2016 (has links)
L'hippocampe, structure cérébrale située dans le lobe temporal, est au coeur de la gestion de nombreuses fonctions cognitives comme l'encodage des informations spatiotemporelles ou encore la mémoire épisodique. A l'heure actuelle, l'hippocampe est étudié via de nombreuses méthodes notamment l'imagerie de fluorescence qui, utilisée sur des animaux éveillés, permet d'accéder au fonctionnement du réseau neuronal. Malgré cela, une sous-région : le gyrus denté a encore un rôle mal élucidé car profondément enfoui dans le cerveau. Son étude permettrait d'apporter de nouveaux éléments sur le fonctionnement de l'hippocampe. De part sa profondeur d’environs 1 mm, son imagerie demeure très difficile. En effet, la diffusion ainsi que les aberrations optiques introduites par les couches successives de matière dégradent fortement la qualité d'imagerie. Pourtant l'optique adaptative, une technique héritée de l'astronomie, pourrait changer cela. En l'intégrant à un microscope bi-photon, il serait possible de compenser les aberrations optiques introduites par le cerveau et ainsi d'arriver à effectuer l'imagerie in vivo du gyrus denté. Durant ma thèse, j'ai donc travaillé à la conception complète tant du point de vue matériel que logiciel d'un microscope bi-photon adapté à l'imagerie in vivo et équipé d'un dispositif de correction de front d'onde. J'ai également développé une méthode d'optimisation prometteuse basée sur l'approche modale de la correction des aberrations optiques couplée à l'utilisation d'une métrique adaptée à l'imagerie non-linéaire en profondeur. Enfin, j'ai pu appliquer cette méthode dans des conditions in vitro et in vivo permettant de montrer son efficacité. / The hippocampus, a cortical structure located in the temporal lobe, is at the heart of the management of many cognitive functions such as spatiotemporal information encoding or episodic memory. At present, the hippocampus is studied through many methods including fluorescence imaging, and used on awake animals, allows access for the study of the neural network function. Despite this, a sub-region: the dentate gyrus has still a poorly elucidated role because it is deeply buried in the brain. His study would bring new elements on the hippocampus functioning. Due to its depth of about 1 mm, its imagery remains very difficult. Indeed, scattering as well as optical aberrations introduced by the successive layers of matter strongly degrade the imaging quality. Yet adaptive optics, a technique inherited from astronomy, could change that. By integrating it into a bi-photon microscope, it would be possible to compensate optical aberrations introduced by the brain and thus to achieve the in vivo imaging of the dentate gyrus. During my PhD, I worked on the complete design both in hardware and software of a bi-photon microscope suitable for in vivo imaging and equipped with a wavefront correction device. I also developed a promising optimization method based on the modal approach of optical aberration correction coupled with the use of a metric adapted to nonlinear depth imaging. Finally, I was able to apply this method in in vitro and in vivo conditions to show its effectiveness.
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Perte de masse des étoiles massives évoluées : l'environnement circumstellaire à haute résolution angulaire / Mass loss of evolved massive stars : the circumstellar environment at high angular resolution

Montarges, Miguel 20 October 2014 (has links)
Les mécanismes physiques de la perte de masse des étoiles évoluées sont encore largement inconnus. Ce processus essentiel est pourtant le moteur principal de l'évolution chimique du milieu interstellaire. Pour les supergéantes rouges (SGR), le déclenchement de l'éjection de la matière et les mécanismes de condensation de la poussière demeurent mal compris. La façon dont les géantes rouges parviennent à former des nébuleuses planétaires non-Sphériques est aussi inconnue. Au cours de ma thèse j'ai étudié des étoiles évoluées grâce à des techniques de haute résolution angulaire permettant de détailler leur surface et leur environnement proche où se trouve l'origine de la perte de masse. À partir d'observations interférométriques en infrarouge (IR), j'ai caractérisé l'enveloppe de vapeur d'eau et de monoxyde de carbone de la SGR Bételgeuse. J'ai également suivi l'évolution d'un point chaud à sa surface et analysé la structure de sa convection ainsi que celle d'Antarès (une autre SGR très proche) grâce à des simulations hydrodynamiques radiatives. L'imagerie à la limite de diffraction (optique adaptative en IR, télescope spatial en ultraviolet) m'a permis d'étudier l'évolution des inhomogénéités de l'enveloppe circumstellaire de Bételgeuse et découvrir un disque circumstellaire autour de L2 Puppis, une étoile de la branche asymptotique des géantes. Ces observations multi-Longueurs d'onde, répétées à plusieurs époques, m'ont permis d'initier un suivi temporel et d'apporter des informations sur la dynamique en jeu. Renouvelé sur un plus grand échantillon d'étoiles dans les années à venir, ce programme permettra de mieux appréhender la perte de masse des étoiles évoluées. / Mass loss of evolved stars is still largely mysterious, despite its importance as the main evolution engine for the chemical composition of the interstellar medium. For red supergiants (RSG), the triggering of the outflow and the mechanism of dust condensation remain unknown. Concerning red giant stars, we still do not know how their mass loss is able to form a bipolar planetary nebula. During my PhD thesis, I observed evolved stars with high angular resolution techniques. They allowed us to study the surface and the close environment of these stars, from where mass loss originates. With near-Infrared interferometric observations, I characterized the water vapor and carbon monoxide envelope of the nearby RSG Betelgeuse. I also monitored a hot spot on its surface and analyzed the structure of its convection, as well as that of Antares (another very nearby supergiant) thanks to radiative hydrodynamical simulations. Diffraction-Limited imaging techniques (near-Infrared adaptive optics, ultraviolet space telescope) allowed me to observe the evolution of inhomogeneities in the circumstellar envelope of Betelgeuse and to discover a circumstellar disk around L2 Puppis, an asymptotic giant branch star. These multi-Scale and multi-Wavelength observations obtained at several epochs allowed us to monitor the evolution of the structures and to derive information on the dynamics of the stellar environment. With a wider stellar sample expected in the next few years, this observing program will allow a better understanding of the mass loss of evolved stars.

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