Made available in DSpace on 2014-12-17T14:55:00Z (GMT). No. of bitstreams: 1 JoabsonNC.pdf: 1023745 bytes, checksum: 5c279305bf7356a4d77b64ca8e0c6261 (MD5) Previous issue date: 2005-12-19 / This work presents a theoretical and numerical analysis using the transverse resonance technique (TRT) and a proposed MTRT applied in the analysis of the dispersive characteristics of microstrip lines built on truncated isotropic and anisotropic dielectric substrates. The TRT uses the transmission lines model in the transversal section of the structure, allowing to analyze its dispersive behavior. The difference between TRT and MTRT consists basically of the resonance direction. While in the TRT the resonance is calculated in the same direction of the metallic strip normal axis, the MTRT considers the resonance in the metallic strip parallel plane. Although the application of the MTRT results in a more complex equivalent circuit, its use allows some added characterization, like longitudinal section electric mode (LSE) and longitudinal section magnetic mode (LSM), microstrips with truncated substrate, or structures with different dielectric regions. A computer program using TRT and MTRT proposed in this work is implemented for the characterization of microstrips on truncated isotropic and anisotropic substrates. In this analysis, propagating and evanescent modes are considered. Thus, it is possible to characterize both the dominant and higher order modes of the structure. Numerical results are presented for the effective permittivity, characteristic impedance and relative phase velocity for microstrip lines with different parameters and dimensions of the dielectric substrate. Agreement with the results obtained in the literature are shown, as well as experimental results. In some cases, the convergence analysis is also performed by considering the limiting conditions, like particular cases of isotropic materials or structures with dielectric of infinite size found in the literature. The numerical convergence of the formulation is also analyzed. Finally, conclusions and suggestions for the continuity of this work are presented / Este trabalho apresenta os fundamentos te?ricos da t?cnica da resson?ncia transversa (TRT) e da t?cnica da resson?ncia transversa modificada (MTRT) aplicada na an?lise das caracter?sticas dispersivas de uma microfita considerando substratos diel?tricos isotr?picos e anisotr?picos truncados. A TRT utiliza o modelo da linha de transmiss?o na se??o transversal da estrutura, permitindo analisar o seu comportamento dispersivo. A diferen?a entre a TRT e MTRT consiste basicamente na dire??o da resson?ncia. Enquanto na TRT a resson?ncia ? calculada ao longo do eixo normal ? fita met?lica, a MTRT considera a resson?ncia no plano paralelo ? fita met?lica. Embora a aplica??o da MTRT resulte num circuito equivalente mais complexo, sua utiliza??o permite a caracteriza??o mais precisa, incluindo modo el?trico de se??o longitudinal (LSE) e modo magn?tico de se??o longitudinal (LSM), microfitas com substrato truncado, ou estruturas planares com multiplas regi?es diel?tricas. Um programa computacional utilizando a TRT e MTRT ? discutido e desenvolvido para caracteriza??o de microfitas sobre substratos isotr?picos e anisotr?picos truncados. Na an?lise, consideram-se modos propagantes e evanescentes. Assim, ? poss?vel caracterizar n?o somente o modo fundamental, mas tamb?m os modos de ordem superior da estrutura. S?o apresentados resultados num?ricos para as diversas grandezas, ou seja, permissividade efetiva, imped?ncia caracter?stica e velocidade de fase relativa para microfita com diferentes par?metros e dimens?es do substrato. S?o feitas compara??es com outros resultados dispon?veis na literatura e, tamb?m, com resultados determinados experimentalmente. Em alguns casos, os resultados s?o comparados como casos particulares de materiais isotr?picos ou de estruturas com diel?tricos de tamanho infinito encontradas na literatura, tendo sido observada uma excelente concord?ncia. Apresenta-se, ainda, um estudo de converg?ncia da formula??o proposta e, finalmente, conclus?es e sugest?es para continuidade do trabalho

Static balance is the reduction or elimination of the actuating effort in quasi-static motion of a mechanical system by adding non-dissipative force interactions to the system. In recent years, there is increasing recognition that static balancing of elastic forces in compliant mechanisms leads to increased efficiency as well as good force feedback characteristics. The development of insightful and pragmatic design methods for statically balanced compliant mechanisms is the motivation for this work. In our approach, we focus on a class of compliant mechanisms that can be approximated as spring-loaded rigid-link mechanisms. Instead of developing static balancing techniques directly for the compliant mechanisms, we seek analytical balancing techniques for the simplified spring–loaded rigid–link approximations. Towards that, we first provide new static balancing techniques for a spring-loaded four-bar linkage. We also find relations between static balancing parameters of the cognates of a four-bar linkage. Later, we develop a new perfect static balancing method for a general n-degree-of-freedom revolute and spherical jointed rigid-body linkages. This general method distinguishes itself from the known techniques in the following respects: 1 It adds only springs and not any auxiliary bodies. 2 It is applicable to linkage shaving any number of links connected in any manner. 3 It is applicable to both constant(i.e., gravity type) and linear spring loads. 4 It works both in planar and spatial cases. This analytical method is applied on the approximated compliant mechanisms as well. Expectedly, the compliant mechanisms would only be approximately balanced. We study the effectiveness of this approximate balance through simulations and a prototype. The analytical static balancing technique for rigid-body linkages and the study of its application to approximated compliant mechanisms are among the main contributions of this thesis.

Orientador: Sandra Augusta Santos / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-10T21:01:17Z (GMT). No. of bitstreams: 1 SilvaJunior_EpitacioPedroda_M.pdf: 1234663 bytes, checksum: 67cac0299f5435bbce39b930a12c49c4 (MD5) Previous issue date: 2008 / Resumo: Este trabalho tem dois objetivos principais. O primeiro é apresentar um contexto aplicado para o uso do Teorema da Função Implícita. Este resultado permite analisar a influência da precisão dos relógios envolvidos no funcionamento do GPS (Global Positioning System), cujo receptor é usado para determinar as coordenadas de um ponto da Terra, O segundo objetivo é estabelecer algumas conexões entre conceitos da Geometria Analítica do Ensino Médio com a,do Ensino Superior, bem como com o Cálculo de Várias Variáveis, aparentemente desconectados para o aluno do Ensino Superior. Para tanto, a idéia foi partir do cálculo da área de regiões simples, como triângulos e polígonos, e chegar à computação de áreas de regiões mais sofisticadas, por meio do Teorema de 'Green. Este resultado permite justificar o funcionamento do aparelho mecânico denominado planímetro / Abstract: The objective of this work is twofold. First, it presents an applied context for using the Implicit Function Theorem. This result allows to analyze the influence of the accuracy of the clocks involved in the working of the GPS (Global Positioning System), the receiver of which is a device used to locate the position of a point on the surface of the earth. Second, it points some connections among concepts of Analytic Geometry, together with Calculus of Several Variables, apparently not linked for the university student. To achieve such goal, the idea was to start with the calculus of the area of simple regions, like triangles and polygons, and reach the computation of more sophisticated areas by using Green's theorem. This result allows to justify the working of the mechanical device called planimeter / Mestrado / Matematica / Mestre em Matemática

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Os conceitos de DecomposiÃÃo em Ãrvore e Largura em Ãrvore foram introduzidos por Robertson e Seymour em sua sÃrie de artigos sobre menores de grafos, publicados ao longo da dÃcada de 90. Sabe-se que muitos problemas NP - difÃceis podem ser resolvidos polinomialmente para um grafo G, dada uma decomposiÃÃo em Ãrvore de G de largura limitada. Logo, limitar a largura em Ãrvore de uma classe de grafos torna-se um objeto de estudo de grande interesse. Neste contexto, a classe dos grafos planares se mostra bastante intrigante, uma vez que, apesar de possuir outras mÃtricas limitadas em valores baixos (por exemplo, nÃmero cromÃtico), nÃo possui largura em Ãrvore limitada. Desta forma, uma alternativa à restringir a classe estudada para uma subclasse dos grafos planares. Neste trabalho, nÃs investigamos a classe dos grafos planares livres de buracos pares. NÃs mostramos que se G à um grafo planar livre de buracos pares, entÃo ele nÃo contÃm uma subdivisÃo de uma grade 10  10. Portanto, se os menores grades de G sÃo obtidos de subdivisÃes G tem largura em Ãrvore no mÃximo 49. AlÃm disso, dois algoritmos nÃo exatos polinomiais para computar uma decomposiÃÃo em Ãrvore de um grafo planar livre de buracos pares sÃo apresentados, ambos baseados em caracterizaÃÃes conhecidas de tal classe de grafos. No primeiro algoritmo, uma decomposiÃÃo em Ãrvore à construÃda a partir de grafos bÃsicos pela concatenaÃÃo de decomposiÃÃes em Ãrvores de pedaÃos pequenos via os cortes clique, k-estrelas (k = 1; 2; 3) e 2-join. No segundo, uma decomposiÃÃo em Ãrvore à construÃda pela inclusÃo dos vÃrtices de G um a um, seguindo sua ordem bi-simplicial. / The definitions of tree decomposition and treewidth were introduced by Robertson and Seymour in their series of papers on graph minors, published during the nineties. It is known that many NP-hard problems can be polynomially solved if a tree decomposition of bounded treewidth is given. So, it is of interest to bound the treewidth of certain classes of graphs. In this context, the planar graphs seem to be specially challenging because, in despite of having many known bounded metrics (for example, chromatic number), they have unbounded treewidth. So, an alternative approach is to restrict ourselves to a subclass of planar graphs. In this work, we investigate the class of even-hole-free planar graphs. We show that if G is an even-hole-free planar graph, then it does not contain a subdivision of the 10Â10 grid. So, if the grid minors of G are obtained from subdivisions, then G has treewidth at most 49. Furthermore, two polynomial, non-exact algorithms to compute a tree decomposition of a even-hole-free planar graph are given, both based on known characterizations of even-hole-free graphs. In the Ârst one, a tree decomposition is built from basic graphs by concatenating the tree decomposition of small pieces via the clique, k-stars (k = 1; 2; 3) and 2-join cutsets. In the second one, a tree decomposition is built by including one by one the vertices of G, following their bi-simplicial order.

Pour les systèmes de communication par satellite, des filtres avec de très bonnes performances électriques sont indispensables afin de rejeter les signaux indésirables dans de nombreuses parties de la chaîne de communication. Les technologies fort-Q peuvent répondre à cette exigence mais elles conduisent souvent à des dispositifs encombrants. D'autre part, les technologies compactes faible-Q souffrent généralement d'une dégradation des performances électriques en termes de pertes d'insertion, de sélectivité et de platitude. Pour répondre à une demande croissante concernant la réduction de la taille, il est essentiel de développer des filtres hyperfréquences compacts avec des performances électriques améliorées.Pour le filtre de réception, le défi est de concevoir un filtre passe-bande compact avec une réponse plate dans la bande passante et une forte réjection hors bande. Les pertes d'insertion ne sont pas cruciales et peuvent être compensées par un amplificateur en laissant ainsi un espace pour la conception de filtre à pertes. Un tel filtre accepte des pertes supplémentaires, qui peuvent être distribués dans le réseau afin de fournir une transmission plate dans la bande passante et une forte sélectivité hors bande.Dans le cadre de cette thèse, des nouvelles méthodes de synthèse de dispositifs de filtrage ont été étudiées et développées dans le but d’améliorer les performances tout en conservant un encombrement réduit. Ces méthodes ont été validées pour la conception de filtres de récepteur dans la charge utile de satellites de télécommunication dans le cadre d’une collaboration entre le laboratoire Xlim, le Centre National d’Etudes Spatiales et Thales Alenia Space. / For satellite communication systems, high performance filters are needed in order to reject unwanted signals in many parts of the communication chain. High quality factor (Q) technologies can meet this requirement, but they often lead to bulky devices. On the other hand, compact technologies are generally low Q and suffer from a degradation of electrical performances in terms of insertion loss, selectivity and flatness. To meet a growing demand concerning size reduction, it is essential to develop compact microwave filters with improved electrical performances.For a receive filter, the challenge is to design a compact bandpass filter with a flat response in the passband and a sharp transition in the passband edges. The insertion loss is not crucial and it can be compensated by the amplifier, leaving a room to the design of a lossy filter. Such a filter accepts additional losses, which can be distributed in the network in order to provide a flat transmission in the passband and a sharp selectivity.In this thesis, new synthesis methods for filtering devices have been studied and developed to improve performances while maintaining a small footprint. These methods have been validated for the design of filters for a receiver in payload satellites as part of collaboration between the Xlim laboratory, the France National Space Centre and Thales Alenia Space.

Les antennes à polarisation circulaire (CP) sont de plus en plus utilisées dans les systèmes de communications spatiaux et terrestres. Le besoin d’intégration est sans cesse plus important, il est donc nécessaire de proposer, de mettre au point des aériens toujours plus compacts et aux performances (adaptation, rayonnement, gain, efficacité, taux d’ellipticité) optimisées. L’objectif de cette thèse est donc de concevoir des antennes planaires, large bande ou multi-bande, à polarisation circulaire et aux performances optimisées. Afin d’atteindre ces objectifs, le travail a été divisée en plusieurs phase, allant de la conception d’une antenne CP à large bande jusqu’à la conception d’une antenne patch à polarisation circulaire tri bandes GNSS. Tout d’abord une étude bibliographique sur les antennes planaires a été faite. Celle-ci a permis de comparer leurs différentes performances, leurs avantages et inconvénients. Ensuite, une antenne patch CP à éléments parasites a été conçue fabriquée et mesurée. On s’est attaché à optimiser sa bande de fonctionnement. En tenant compte des études bibliographiques déjà faites, et en se basant sur la structure de l’antenne CP à large bande validée lors de la phase précédente, une nouvelle antenne plaquée CP GNSS tri bandes a également été conçue réalisée et mesurée. L’essentiel du travail a consisté à minimiser son encombrement tout en conservant des performances électromagnétiques satisfaisantes dans les trois bandes de fréquences objectifs : L2, E6 et L1. On s’est particulièrement attaché à obtenir un bon taux d’ellipticité sur une large ouverture rayonnante. La dernière étape de cette thèse a consisté à aller encore plus loin dans l’amélioration des performances de l’antenne CP GNSS multi bandes particulièrement en améliorant son efficacité. Une excitation par fente a finalement été utilisée après comparaison des performances obtenues via différentes techniques (alimentation coaxiale, fentes, etc…). / Circular polarized antennas (CP) are greatly used in space and terrestrial communication systems. Furthermore, the need for communication systems integration is increasingly important. Therefore, it is necessary to propose and develop more compact antenna design with optimized performance (adaptation, radiation, gain, efficiency, axial ratio).The objective of this thesis is to design planar antennas, broadband or multi-band, with circular polarization and optimized performances. To achieve these objectives, the work was divided into several stages, from the design of a wideband CP antenna to the design of a GNSS tri-band circular polarized patch antenna. Firstly, a literature study of planar antennas has been conducted. Different designs have been examined and contrasted to evaluate their performances. Secondly, a wideband CP patch antenna with parasitic elements has been designed manufactured and measured. It was sought to optimize its operating band. Considering the bibliographical study that was already carried out, and based on the wideband CP antenna structure that was validated during the previous phase, a new GNSS tri-band CP patch antenna was also designed, fabricated and measured. Most of the work was done on minimizing its size while maintaining satisfactory electromagnetic performance in the three required GNSS frequency bands : L2, E6 and L1. Special attention was directed towards getting a good axial ratio over a wide radiating aperture. The last phase of this thesis was to go even further in improving the CP GNSS multi-band antenna's performance, particularly by improving its efficiency. Excitation slots were finally used after a comparison was made between the different performances obtained through the different design techniques (coaxial feed, slots, etc ...).

Doctor of Philosophy / Department of Biology / Michael A. Herman / The polarities of several cells that divide asymmetrically during C. elegans development are controlled by Wnt signaling. LIN-44/Wnt and LIN-17/Fz control the polarities of cells in the tail of developing C. elegans larvae, including the male-specific blast cell, B, which divides asymmetrically to generate a larger anterior daughter and a smaller posterior daughter. We determined that the canonical Wnt pathway components are not involved in the control of B cell polarity. However, POP-1/Tcf is involved and asymmetrically distributed to B daughter nuclei. Aspects of the B cell division are reminiscent of the divisions controlled by the planar cell polarity (PCP) pathway that has been described in both Drosophila and vertebrate systems. We identified C. elegans homologs of Wnt/PCP components and have determined that many of them appear to be involved in the regulation of B cell polarity and POP-1 asymmetric distribution to B daughter nuclei. Thus a non-canonical Wnt pathway, which is different from other Wnt pathways in C. elegans, but similar to the PCP pathways, appears to regulate B cell polarity. Molecular mechanisms of this PCP pathway were also investigated. We determined that LIN-17/Fz is asymmetrically distributed to the B cell cortex prior to, during, and after, division. Furthermore, the asymmetric localization of LIN-17::GFP is controlled by LIN-44/Wnt and MIG-5/Dsh. The cysteine rich domain (CRD), seven trans-membrane domain and KTXXXW motif of LIN-17 are required for LIN-17 to rescue lin-17, while only seven trans-membrane domains and KTXXXW motif are required for LIN-17 asymmetric localization. MIG-5::GFP asymmetrically localized to the B cell prior to and after division in a LIN-17/Fz dependent manner. We examined the functions of these MIG-5 domains. The DEP domain is required for MIG-5 membrane association, while the PDZ domain is responsible for different levels of MIG-5 in the B daughters. The DEP and PDZ domain are required to rescue B cell polarity defect of mig-5 males, while the DIX domain is not that important. In summary, a novel PCP-like pathway, in which LIN-17 and MIG-5 are asymmetrically localized, is conserved in C. elegans and involved in the regulation of B cell polarity.

Les actionneurs numériques sont composés d'une partie mobile pouvant se déplacer entre des positions discrètes précisément connues et répétables. Contrairement aux actionneurs analogiques classiques, le pilotage d'actionneurs numériques est réalisé très simplement à l'aide d'une commande impulsionnelle et en boucle ouverte. De ce fait, aucun capteur n'est nécessaire ce qui facilite leur intégration dans des systèmes hôtes. La qualité de fabrication de ces actionneurs est cependant primordiale car une éventuelle erreur ne peut pas être corrigée par la commande. Les travaux présentés porteront sur un réseau composé de 25 actionneurs numériques disposant chacun de quatre positions discrètes avec un plateau glissant. L'application visée est la réalisation d'un système de convoyage planaire dans laquelle les actionneurs permettent de déplacer un plateau selon les deux directions du plan. Les résultats de la simulation sont comparés avec les résultats expérimentaux. En suite, un réseau composé de quatre actionneurs numériques avec un plateau structuré est étudié. La conception du réseau d'actionneurs puis la stratégie de pilotage permettant de réaliser le déplacement du plateau structuré seront tout d'abord présentées. Un prototype de réseau d'actionneurs et des résultats expérimentaux de convoyage selon une direction sera ensuite détaillé et l'influence d'erreurs de fabrication sur le fonctionnement du réseau sera mise en évidence. / The open loop control is widely used by the digital systems to facilitate the integration in complex systems because no sensor is needed. The research is based on digital actuator which is composed of a mobile part and a fixed part. The actuator moves between the discrete positions. The discrete displacement consumes low energy, which is controlled by impulse only needed to switch the actuator between the discrete positions. However, the stroke of digital actuator is fixed at the manufacturing. So the digital actuators array is used to obtain variable strokes. A digital actuators array used here with a structured plate is applied as a 2D planar conveyance. Firstly, an actuators array composed of 25 elementary actuators with a flat plate is studied. The simulated results are compared with the experimental results. Then another actuators array composed of four elementary actuators with a structured plate is designed. The design and the plate displacement are firstly presented. Then the prototype of the conveyance is fabricated with laser cutting machine and 3D printer. The experiment is then tested in one direction to study the plate displacement. The open loop control is simple by using current impulse. The operation can be well functioned which is observed during the experiment. The experimental results are compared with the theoretical results.

L'invention de l'antenne fût à la base de la création des communications sans fil à l'orée du XXe siècle. A l'origine des objets métalliques destinés à transmettre et recevoir des ondes électromagnétiques, les antennes n'ont cessé de se complexifier pour satisfaire l'impressionnant développement des communications sans fil. C'est dans ce contexte qu'est né le concept d'antenne « wearable » il y a moins de deux décennies ouvrant un nouveau champ de recherche sur les antennes souples. C'est dans ce cadre que ce travail de thèse se consacre à la conception d’antennes souples en bande UHF.Une première étude a permis de concevoir une antenne Vivaldi antipodale [150 - 900 MHz] souple pour la Section Technique de l'Armée de Terre. Six de ces antennes sont destinées à être placées sous un ballon gonflé à l'hélium pour réceptionner des signaux RF.Une seconde étude est effectuée en collaboration avec la société Syrlinks et le CNES. L'objectif du projet est de concevoir des antennes souples pour le suivi de personnes avec le système ARGOS (401 et 466 MHz). La solution retenue est une PIFA planaire de largeur inférieure à lambda/3. Elle a l'avantage d'être fine et légère. Le matériau souple employé est un caoutchouc silicone sélectionné parmi plusieurs matériaux souples grâce à des caractérisations diélectriques. Cependant, le problème de cette antenne est qu'elle possède un rayonnement quasi-omnidirectionnel. Etant donné qu'il n'était pas envisageable d'utiliser un plan réflecteur métallique pour des raisons de dimensions, il a été décidé de concevoir un conducteur magnétique artificiel (CMA) souple. Toutefois, la conception de CMA dans le bas de la bande UHF se heurte à des difficultés de miniaturisation. Pour contourner ce problème, il a été développé deux concepts de CMA à cellules unitaires de faibles dimensions devant la longueur d'onde. La première solution utilise des capacités interdigitées et la seconde une structure double couche. Pour ces deux concepts, un modèle circuit est proposé et validé par des mesures expérimentales. Les mesures de l'association CMA - antenne montrent une bande passante suffisante pour des applications ARGOS et un rayonnement majoritairement dirigée dans la direction opposé à celle du CMA. / The invention of antennas was the base of wireless communications appearance at the dawn of the twentieth century. Originally metal objects for transmitting and receiving electromagnetic waves, antennas have steadily become more complex to meet the impressive development of wireless communications. It is in this context that the concept of wearable antennas was born less than two decades ago opening a new field of research namely flexible antennas. It is in this framework that this thesis is dedicated to the design of flexible antennas for UHF band.A first study enabled the design of a flexible antipodal Vivaldi antenna [150-900 MHz] for Technical Section of the Army. Six of these antennas are intended to be placed under a balloon inflated with helium for receiving RF signals.A second study was conducted in collaboration with the company Syrlinks and CNES. The objective of the project is to design flexible antennas for tracking people with ARGOS system (401 and 466 MHz). The selected solution is a planar PIFA which width is smaller than lambda/3. This antenna has the advantage of being thin and light. The flexible material used is a silicone rubber and it was selected among several others due to some dielectric characterizations. However, the drawback of this antenna is that it has a quasi-omnidirectional radiation pattern. Since it was not possible to use a reflector metal plane due to size constraints, it was decided to design a flexible artificial magnetic conductor (AMC). However, the design of AMCs in the lower UHF band is challenged with the miniaturization difficulties. Two concepts of small size (compared to the wavelength) AMCs unit cells were developed to work around this problem. The first solution uses interdigitated capacitors and the second a double layer structure. For these two concepts, a circuit model is proposed and validated by experimental measurements. The measurement of the AMC associated antenna demonstrates a bandwidth sufficient for ARGOS applications and a radiation pattern mostly directed in the direction opposite to that of the AMC.

The present work is concerned with fundamental studies on the liquid fuel transport in the intake manifold of small carburetted engines. This work is motivated by the need for development of technologies to meet the stringent cold-start emission norms that are to be prescribed for two-wheelers in particular. More specifically, visualization studies conducted in a transparent manifold made of quartz in a small four-stroke 110-cc two-wheeler engine have shown the presence of gasoline films on the walls of the inlet manifold under cold start conditions. Advanced Laser diagnostic techniques such as Planar Laser Induced Fluorescence (PLIF) have been utilized to measure the thickness of the fuel films. The Sauter Mean Diameter for the fuel droplets at the carburettor exit is measured using Laser Shadowgraphy technique. It is observed that the films are present both at idling conditions and under load. This large amount of liquid fuel entering the engine leads to incomplete combustion and higher emissions of unburned hydrocarbons. A detailed analysis of the effects of heating the inlet manifold has been performed. The potential of this manifold heating strategy in reducing hydrocarbon emissions has been assessed and found to be promising. In addition, a need of proper control of the fuel exiting the carburettor is shown to reduce emissions and increase fuel efficiency.