São crescentes as pesquisas e os projetos envolvendo o eletromagnetismo. Tanto para as pesquisas quanto para os projetos, tem-se o recurso de realizar simulações computacionais dos problemas envolvidos, a fim de investigar o comportamento dos fenômenos eletromagnéticos diante da situação na qual encontram-se. Há casos, contudo, em que o problema pode ficar computacionalmente grande, requisitando maior quantidade de memória e maior tempo de processamento, devido às geometrias envolvidas ou à acuracidade desejada. Com o objetivo de contornar estas questões, tem-se o desenvolvimento da computação paralela. Uma das implementações possíveis de sistema paralelizado é por meio de uma rede de computadores e, empregando-se programas gratuitos, tem-se sua realização a custo praticamente nulo. O presente trabalho, utilizando o método FDTD, visa a implementação de tal sistema paralelizado. Entretanto, na etapa de desenvolvimento, uma especial atenção foi dada às boas práticas de programação, com o objetivo de garantir ao programa flexibilidade, modularidade e expansibilidade. Adicionalmente, desenvolveu-se uma ferramenta matemática para estimar o tempo de processamento total de uma simulação paralelizada, além de fornecer indicativos de ajustes de parâmetros para que este tempo seja o menor possível. Validam-se o código, o sistema paralelizado e a ferramenta matemática com alguns exemplos. Finalmente, realiza-se um estudo para uma aplicação prática de interesse com a ferramenta desenvolvida. / Researches and projects involving electromagnetic problems are continuously increasing. As much for researches as for projects, there is a resource of achieving computer simulations for the involved problems aiming to investigate the electromagnetic phenomenons behavior, in the situation they are. There are cases, however, the problem results in high computational size, requesting more memories sizes and high processing times, because of the given geometries or high accuracy wanted. With the intent of solving these questions, the parallel computation developing becomes interesting. One of the possible implementations of this parallel system is the use of a computer network. Besides, using free programms, the implementation has almost any costs. The present work, using the FDTD method, aims at the implementation of this parallel system. However, during the development stage, a special attention was given to the programming practices, with the intent of guaranteeing the flexibility, modularity and expansibility of the program. In addition, a mathematic tool was developed to estimate the total processing time of the parallel simulation and to predict indications for adjustments of parameters to reach the minimum time possible. The code, the parallel system and the mathematic tool are validated with some examples. Finally, a study for a practical aplication of interest is done with the developed tool.

São crescentes as pesquisas e os projetos envolvendo o eletromagnetismo. Tanto para as pesquisas quanto para os projetos, tem-se o recurso de realizar simulações computacionais dos problemas envolvidos, a fim de investigar o comportamento dos fenômenos eletromagnéticos diante da situação na qual encontram-se. Há casos, contudo, em que o problema pode ficar computacionalmente grande, requisitando maior quantidade de memória e maior tempo de processamento, devido às geometrias envolvidas ou à acuracidade desejada. Com o objetivo de contornar estas questões, tem-se o desenvolvimento da computação paralela. Uma das implementações possíveis de sistema paralelizado é por meio de uma rede de computadores e, empregando-se programas gratuitos, tem-se sua realização a custo praticamente nulo. O presente trabalho, utilizando o método FDTD, visa a implementação de tal sistema paralelizado. Entretanto, na etapa de desenvolvimento, uma especial atenção foi dada às boas práticas de programação, com o objetivo de garantir ao programa flexibilidade, modularidade e expansibilidade. Adicionalmente, desenvolveu-se uma ferramenta matemática para estimar o tempo de processamento total de uma simulação paralelizada, além de fornecer indicativos de ajustes de parâmetros para que este tempo seja o menor possível. Validam-se o código, o sistema paralelizado e a ferramenta matemática com alguns exemplos. Finalmente, realiza-se um estudo para uma aplicação prática de interesse com a ferramenta desenvolvida. / Researches and projects involving electromagnetic problems are continuously increasing. As much for researches as for projects, there is a resource of achieving computer simulations for the involved problems aiming to investigate the electromagnetic phenomenons behavior, in the situation they are. There are cases, however, the problem results in high computational size, requesting more memories sizes and high processing times, because of the given geometries or high accuracy wanted. With the intent of solving these questions, the parallel computation developing becomes interesting. One of the possible implementations of this parallel system is the use of a computer network. Besides, using free programms, the implementation has almost any costs. The present work, using the FDTD method, aims at the implementation of this parallel system. However, during the development stage, a special attention was given to the programming practices, with the intent of guaranteeing the flexibility, modularity and expansibility of the program. In addition, a mathematic tool was developed to estimate the total processing time of the parallel simulation and to predict indications for adjustments of parameters to reach the minimum time possible. The code, the parallel system and the mathematic tool are validated with some examples. Finally, a study for a practical aplication of interest is done with the developed tool.

Made available in DSpace on 2014-12-17T14:55:39Z (GMT). No. of bitstreams: 1 LincolnMA.pdf: 1667449 bytes, checksum: b8113389f31903ba22cf94dbc22192c1 (MD5) Previous issue date: 2009-08-13 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / This work presents a theoretical and numerical analysis of structures using frequency selective surfaces applied on patch antennas. The FDTD method is used to determine the time domain reflected fields. Applications of frequency selective surfaces and patch antennas cover a wide area of telecommunications, especially mobile communications, filters and WB antennas. scattering parameters are obteained from Fourier Transformer of transmited and reflected fields in time domain. The PML are used as absorbing boundary condition, allowing the determination of the fields with a small interference of reflections from discretized limit space. Rectangular patches are considered on dielectric layer and fed by microstrip line. Frequency selective surfaces with periodic and quasi-periodic structures are analyzed on both sides of antenna. A literature review of the use of frequency selective surfaces in patch antennas are also performed. Numerical results are also compared with measured results for return loss of analyzed structures. It is also presented suggestions of continuity to this work / Este trabalho apresenta uma an?lise te?rica e num?rica de estruturas que utilizam superf?cies seletivas de frequ?ncia aplicadas a antenas do tipo patch. Para isso, ? utilizado o m?todo das diferen?as finitas no dom?nio do tempo (FDTD) visando determinar os campos refletidos a partir de uma onda plana incidente no dom?nio do tempo. As aplica??es das superf?cies seletivas de freq??ncia e antenas patch abrangem uma grande ?rea das Telecomunica??es, principalmente em comunica??es m?veis e v?o desde filtros at? as antenas banda larga. Especificamente, a an?lise usa os campos transmitidos e refletidos obtidos no dom?nio do tempo, em conjunto com transformada de Fourier permitindo a obten??o dos par?metros de transmiss?o da antena. A condi??o de contorno absorvedora utilizada foi a de camada perfeitamente casada (PML), permitindo a determina??o num?rica dos campos com uma quantidade menor de interfer?ncias provenientes de reflex?es nos limites do espa?o discretizado. S?o considerados patches retangulares condutores sobre uma camada diel?trica e alimentados por linha de microfita. Foram analisadas superf?cies seletivas de frequ?ncia peri?dicas e quase peri?dicas tanto no plano de terra quanto no plano do pr?prio patch. ? realizada uma revis?o bibliogr?fica a respeito da utiliza??o de superf?cies seletivas de frequ?ncia em antenas patch. Tamb?m s?o comparados resultados num?ricos e medidos para a perda de retorno das estruturas analisadas. S?o apresentadas, ainda, sugest?es de continuidade para este trabalho

Perfectly matched layer (PML) is a commonly used method of absorbing waves at a computational boundary for partial differential equation (PDE) problems. In this thesis, methods for improving the usability of implementations in Comsol Multiphysics is addressed. The study looks at complex coordinate stretching PMLs in the context of Helmholtz equation using the finite element method (FEM). For a PML to work it has to be set up properly with parameters that takes into account the properties of the problem. It is not always straight forward. Some theory behind PMLs is presented and experimentation on PML properties performed. Methods for PML optimization and adaption is presented. Currently, the way PMLs is applied in COMSOL Multiphysics requires the user to perform many tasks; setting up a geometry, meshing and choosing a suitable complex coordinate stretching. Using a so-called extra-dimension implementation it is possible to attach PMLs as boundary conditions in COMSOL Multiphysics. This simplifies for the user since the geometry and mesh is handled by the software. / Perfectly matched layer (PML) är en metod som ofta används för vågabsorbering vid randen för problem med partiella differentialekvationer (PDE). I det här examensarbetet presenteras metoder som förenklar användingen av PMLer i COMSOL Multiphysics. Studien kollar på PMLer baserade på komplex-koordinatsträckning med fokus på Helmholtz ekvation och finita elementmetoden (FEM). För att en PML ska fungera måste den sättas upp på rätt sätt med parametrar anpassade efter det givna problemet. Att göra detta är inte alltid enkelt. Teori presenteras och experiment på PMLer görs. Flera metoder för optimisering och adaption av PMLer presenteras. I nuläget kräver appliceringen av PMLer i COMSOL Multiphysics att användaren sätter upp en geometri, ett beräkningsnät och väljer den komplexa koordinatsträckningen. Genom att använda COMSOLs implementation av extra dimensioner är det möjligt att applicera PMLer som randvilkor. I en sådan implementation kan geometri och beräkningsnät skötas av mjukvaran vilket underlättar för användaren.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Ce travail s'intéresse à la résolution du système de Maxwell dans le domaine temporel sur des maillages héxaédriques orthogonaux localement raffinés de manière conforme ou non-conforme. Une méthode de Galerkin discontinu, reposant sur une approximation centrée pour le calcul des intégrales de surface et un schéma saute-mouton d'ordre 2 pour l'intégration temporelle est présentée. On définit ainsi une classe de schémas non-diffusifs : un équivalent discret de l'énergie électromagnétique est conservée.

Les travaux de cette thèse concernent le rayonnement acoustique d'une source périodique en temps placée dans un conduit Infini, contenant un guide en écoulement parallèle cisaille. Le phénomène est modélise a l'aide de l'équation de Galbrun, dont l'inconnue u est la perturbation de déplacement. L'objectif de cette étude est de développer une méthode éléments Nis, susceptible d'être étendue à des géométries et des écoulements plus complexes. Cette thèse fait suite a celle de Guillaume Legendre qui a établi, dans le cas d'un ecoulement uniforme, une formulation dite régularisée de l'´equation de Galbrun afin de corriger un défaut d'ellipticité. Le but de ce manuscrit est détendre cette méthode à un écoulement non uniforme. La difficulte supplémentaire vient du fait que la vorticite ψ = rot u (qui intervient dans le terme de régularisation) ne peut plus être calculée a priori car le cisaillement induit un couplage entre acoustique et hydrodynamique. En régime dissipatif, nous avons explicite ψ en fonction de u à l'aide d'une convolution (le long des lignes de courant). Si l'ecoulement est lent, cette formule de convolution (qui devient une intégrale très oscillante) peut être approchée par une formule differentielle beaucoup plus simple dont l'utilisation conduit a un modèle ”faible Mach”. Des idées similaires ont ensuite été utilisées pour résoudre le problème non dissipatif, a l'aide de couches PML. Les deux approches (exacte et ”faible Mach”) ont été validées par des tests numériques en 2D et en 3D.

PML et les corps nucléaires (CN) sont impliqués dans la défense antivirale. En effet, notre équipe a montré que la surexpression de PMLIII confère la résistance au virus de la stomatite vésiculaire, au virus de l'influenza, au virus foamy mais pas au virus de l'encéphalomyocardite (EMCV). J'ai montré dans mon travail de thèse que l'EMCV contrecarre le pouvoir antiviral de PMLIII en induisant sa dégradation par un processus dépendant du protéasome et de SUMO. Cependant, les cellules de souris invalidées pour PML sont plus sensibles à l'infection par l'EMCV que les cellules issues de souris parentales. Pour déterminer l'isoforme de PML responsable de cet effet antiviral, j'ai analysé l'effet des sept isoformes de PML (PMLI-VII) et j'ai montré que seule l'expression en stable de PMLIV confère la résistance à l'EMCV en séquestrant la polymérase virale 3Dpol au sein des CN PML. De plus la déplétion de PMLIV augmente la production de l'EMCV dans les cellules traitées par l'interféron. Ces données indiquent le mécanisme par lequel PML confère la résistance à l'EMCV et révèlent que PML est l'une des protéines médiatrices des effets anti-EMCV de l'interféron.

Epstein-Barr virus (EBV) latent infection is associated with lymphoid and epithelial tumours, including nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC). Since EBNA1 protein is expressed in all EBV tumours, I explored whether EBNA1 alters the cellular environment in ways that would contribute to the development of these epithelial tumours. I have shown that EBNA1 disrupts nuclear bodies (NBs) formed by the PML tumor suppressor and degrades PML proteins in a proteasome dependent manner in NPC and GC cell lines. I have verified the role of EBNA1 in disrupting PML NBs through overexpression and silencing of EBNA1 and shown that EBNA1 alone is sufficient to mediate these effects. Using EBNA1 mutants I found that USP7 and protein kinase CK2 (two enzymes that negatively regulate PML NBs) are important for EBNA1-mediated disruption of PML NBs. Furthermore, I have shown that EBNA1 localizes to PML NBs, and interacts with PML IV, which mediates the enrichment of USP7 and CK2β with PML NBs and increases CK2 phosphorylation of PML proteins, a known prerequisite for PML degradation. Consequently, functions downstream of PML were impaired in the presence of EBNA1. In particular, cells expressing EBNA1 had decreased levels of p53acetylation, p21 and apoptosis in response to DNA damage. Furthermore, DNA repair was markedly impaired in these cells, despite the fact that they survived better after induction of DNA damage than cells lacking EBNA1. In keeping with these observations, immunohistochemistry staining of GC biopsies showed that EBV-positive GC biopsies had lower PML staining compared to EBV-negative samples. These results show that EBNA1 directly affects host cell processes that would be expected to promote malignant transformation. Additionally, I have shown that EBNA1's ability to disrupt PML NBs is important for reactivation of EBV from latency; hence, is required for efficient spread of EBV from host to host.

Epstein-Barr virus (EBV) latent infection is associated with lymphoid and epithelial tumours, including nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC). Since EBNA1 protein is expressed in all EBV tumours, I explored whether EBNA1 alters the cellular environment in ways that would contribute to the development of these epithelial tumours. I have shown that EBNA1 disrupts nuclear bodies (NBs) formed by the PML tumor suppressor and degrades PML proteins in a proteasome dependent manner in NPC and GC cell lines. I have verified the role of EBNA1 in disrupting PML NBs through overexpression and silencing of EBNA1 and shown that EBNA1 alone is sufficient to mediate these effects. Using EBNA1 mutants I found that USP7 and protein kinase CK2 (two enzymes that negatively regulate PML NBs) are important for EBNA1-mediated disruption of PML NBs. Furthermore, I have shown that EBNA1 localizes to PML NBs, and interacts with PML IV, which mediates the enrichment of USP7 and CK2β with PML NBs and increases CK2 phosphorylation of PML proteins, a known prerequisite for PML degradation. Consequently, functions downstream of PML were impaired in the presence of EBNA1. In particular, cells expressing EBNA1 had decreased levels of p53acetylation, p21 and apoptosis in response to DNA damage. Furthermore, DNA repair was markedly impaired in these cells, despite the fact that they survived better after induction of DNA damage than cells lacking EBNA1. In keeping with these observations, immunohistochemistry staining of GC biopsies showed that EBV-positive GC biopsies had lower PML staining compared to EBV-negative samples. These results show that EBNA1 directly affects host cell processes that would be expected to promote malignant transformation. Additionally, I have shown that EBNA1's ability to disrupt PML NBs is important for reactivation of EBV from latency; hence, is required for efficient spread of EBV from host to host.