En esta tesis se presenta un método para analizar antenas montadas sobre estructuras arbitrarias. La Optica Geométrica (GO) y la Teoría Uniforme de la difraccion (UTD), han sidoempleadas para analizar los efectos que la estructura produce sobre el diagrama de radiación de la antena emisora. Para la descripción geométrica de la estructura, han sido utilizados parches NURBS (Non Uniform Rational B-Spline), por lo que el método presentado, es compatible con la mayoría de los programas gráficos disponibles en el mercado.EL tratamiento de geometrías arbitrarias requiere un código eficiente en el análisis de tres dimensiones.Por otro lado, para obtener resultados satisfactorios, la descripción de la superficie de la estructura, debe ser muy próxima al modelo real, sin embargo, esto complica el tratamiento computacional. Aquí la estructura es modelada mediante un conjunto de parches NURBS, que unidos entre sí, describen el modelo completo. Esta descripción permite manipular superficies arbitrarias con un bajo numero de parches, lo que significa un volumen de información reducido.La descripción inicial por NURBS del modelo, es acompañada con información complemetaria como por ejemplo: la tipología de las superficies, las curvas frontera, el tipo de material, etc. Esto es imprescindible para la aplicación de criterios de selección dedicados a la aceleración del proceso.El método tras leer la descripción del modelo, descompone los parches NURBS en superficies racionales de Bezier. Un parche de Bezier es también una superficie paramétrica definida en términos de una combinación lineal de los polinomios de Bernstein.Las antenas son modeladas usando modelos numéricos simples basados en agrupaciones de dipolos infinitesimales eléctricos y magnéticos. Esta caracterización de la antena es muyventajosa ya que con un numero reducido de datos de entrada, la fuente queda definida para cualquier dirección del espacio y el valor del campo radiado puede ser calculado fácilmente.El análisis electromagnético de los efectos que contribuyen al campo dispersado por la geometría comienza con una selección rigurosa de la geometría iluminada desde la fuente.Unicamente los parches de Bezier iluminados serán almacenados por el ordenador durante el análisis. La filosofía de este proceso es descartar aquella parte de la geometría que no contribuye a los efectos de dispersión.El campo total calculado es la superposición de los siguientes efectos pertenecientes a la GO y a la UTD: campo directo procedente de la fuente, campo reflejado por los parches de Bezier, campo difractado por las aristas del modelo definidas como curvas de Bezier, ondas de superficie, dobles reflexiones, reflexione-difraccion y difraccion-reflexión. El método ha sido diseñado para analizar campo cercano y lejano. El mayor gasto computacional se debe a la búsqueda de los puntos de dispersión, por lo que antes de emplear los algoritmos de intersección es necesario aplicar un conjunto de criterios rápidos dependientes de la dirección de observación.El principio de Fermat en combinación con el Gradiente Conjugado (CGM) es usado para obtener de manera eficiente los puntos de dispersión sobre la estructura. Para cada efecto, laposible ocultación de la trayectoria completa del rayo es examinada, por ello, si el rayo corta alguno de los parches de Bezier su contribución será descartada. Los dobles efectos son tratados como una generalización de los simples efectos.El método desarrollado es eficiente ya que precisa de un numero reducido de superficies para modelar objetos complejos lo que se traduce en bajos requerimientos de memoria y reducidos tiempos de calculo. / In this thesis a method to analyze antennas on board of complex bodies is presented. The Geometrical Optics (GO) and Uniform Theory of Diffraction (UTD) have been used to analyze the effect of the structure in the radiation pattern of the antennas. The bodies are geometrically modelled by using NURBS (Non Uniform Rational B-Spline) surfaces. In addition to be accurate and efficient, the method is compatible with most of the modern CAGD (Computer Aided Geometric Design) available programs.The treatment of arbitrary geometries requires a code which can carry out an efficient 3D analysis. To obtain accurate results the description of the surface must be close to the real model, however this complicates the computational procedure. Here the structure is modeled by a collection of individual N.U.R.B.S. surface patches joined to form a complete description of the surface model. The NURBS description is able to manipulate free form surfaces with a low number of patches, and therefore, with a low amount of information. The initial description of the model by NURBS surfaces is accompanied with other complementary data for example : the topology of the surfaces, the boundary curves, the types of material and other inputs. It is very interesting to apply criteria to make the complete analysis faster.The method reads the NURBS description of the model and transforms the NURBS into the rational BEZIER surfaces. A rational BEZIER patch is also a parametric surface defined in terms of a linear combination of Bernstein polynomials.The antennas are modelled using simple numerical models based on arrays of electric and magnetic infinitesimal dipoles. This antenna modelization is very advantageous because with a little input data, the source is defined in any direction and the field value is readily accessible.The electromagnetic analysis of the contributive effects to the scattering field by the geometry, starts with the rigorous selection of the geometry illuminated from the source. Only the Bezier patches illuminated will be in memory of the computer during the analysis. The philosophy of this previous process is to discard in the process the part of the geometry which does not contribute to the scattering effects.The total field is the superposition of the following GO and UTD field components: direct field from the source, reflected fields from the Bezier patches of the model, diffracted fields from the arbitrary edges defined as a Bezier curves, creeping waves, double reflected field and diffracted-reflected and reflected-diffracted fields. The search of specular and diffraction points are the most CPU time consuming, thus before using the intersection algorithms it is necessary to apply a set of fast selection criteria which depend on the observation direction.The Fermat principle in conjunction with the Conjugate Gradient Method (CGM) is used for obtaining efficiently the reflection points and diffraction points on the structure. For each effect the complete ray path is examined to see whether or not it is interrupted by any Bezier patch of the model, in this case the field component is not computed. The double effects are treated using a generalization of the single effects algorithms. The method has been developed to analyze the near and far field cases for different frequencies.The developed method is quite efficient because it makes use of a small number of surfaces to model complex bodies, so it requires few memory and low computing time.

La thèse, dont le sujet est "Modélisation de la propagation électromagnétique en milieux à gradient d'indice basée sur les faisceaux gaussiens - Application à la propagation en atmosphère réaliste et à la radio-occultation entre satellites" a été commencée le 2 décembre 2013, au Département ÉlectroMagnétisme et Radar (DEMR) de l'Onera de Toulouse et avec le laboratoire LAPLACE de l'Université Paul Sabatier. Elle est co-financée par l'ONERA et par la Région Midi-Pyrénées. L'encadrement a été assuré par Jérôme Sokoloff (Laplace/UPS, directeur de thèse), Alexandre Chabory (ENAC, co-directeur) et Vincent Fabbro (ONERA). L'École Doctorale est l' "École Doctorale Génie Électrique, Électronique, Télécommunications : du système au nanosystème". Le faisceau gaussien a été principalement utilisé dans la recherche scientifique afin d'étudier les systèmes optiques tels que les lasers. Des études plus rares et plus récentes ont proposé de l'utiliser pour modéliser la propagation des ondes sismiques. Ses propriétés spatiales et spectrales ont amené certains auteurs à étudier son utilisation dans des modèles de propagation atmosphériques. Cette thèse a consisté à développer un modèle, appelé GBAR (Gaussian Beam for Atmospheric Refraction), de propagation troposphérique réaliste et déterministe en utilisant le formalisme des faisceaux gaussiens. La démarche adoptée a consisté à reprendre les équations fondamentales introduites par Cerveny et Popov décrivant de façon itérative la propagation d'un faisceau gaussien en milieu inhomogène, sous hypothèse de haute fréquence (modèle asymptotique). De nouvelles équations ont été développées à partir d'elles pour obtenir une description analytique de la propagation d'un faisceau gaussien dans un milieu troposphérique décrit par les variations spatiales de l'indice de réfraction. L'hypothèse de base pour l'obtention de la formulation analytique est que le gradient de l'indice de réfraction peut être considéré vertical et constant au voisinage du faisceau. Les équations analytiques pour la description de la propagation d'un seul faisceau ont ensuite été étendues à la modélisation d'un champ quelconque dans un milieu troposphérique pouvant contenir de fortes variations du gradient d'indice, y compris des inversions de gradient. Ceci a été réalisé en couplant les équations analytiques avec la procédure de décomposition multi-faisceaux développée dans sa thèse pas Alexandre Chabory. Le modèle GBAR a été validé dans des milieux troposphériques réalistes issus de simulations du modèle météo méso-échelle WRF (Weather Research and Forecasting). Dans un troisième temps, le modèle a été utilisé pour simuler des inversions de données de radio-occultation. Des outils existent pour fournir un modèle d'interprétation de ces données pour estimer les propriétés physiques de l'atmosphère à partir des mesures en phase, amplitude, Doppler et délai des signaux GNSS transmis entre satellites en orbite autour de la Terre / The subject of this PhD thesis is " Electromagnetic propagation modeling in inhomogeneous media with refractive index gradients based on Gaussian beams - Application to realistic atmospheric propagation and radio occultation between satellites ". The study started on december 2nd, 2013 at the DEMR (Département Électromagnétisme et Radar) department of the ONERA research laboratory, in Toulouse, France. It was funded both by the ONERA and Région Midi-Pyrénées. It was supervised by Jérôme Sokoloff (LAPLACE/UPS, thesis director), Alexandre Chabory (ENAC, thesis co-director) and Vincent Fabbro (ONERA). The doctoral school was "École Doctorale Génie Électrique, Électronique, Télécommunications : du système au nanosystème ". The Gaussian beam was mostly used in scientific investigations to study optical systems such as lasers. Rarer and more recent works suggested the use of the Gaussian beam formalism in order to model the propagation of seismic waves. The properties of the Gaussian beam also led some authors to develop models for atmospheric propagation. In this thesis a model based on Gaussian beams called GBAR (Gaussian Beam for Atmospheric Refraction) was developped for tropospheric propagation in realistic and deterministic conditions. The scientific approach consisted in rewritting the fundamental equations introduced by Cerveny and Popov describing iteratively the propagation of a Gaussian beam in inhomogeneous media, under the high-frequency assumption (asymptotic model). New equations were derived from them in order to get analytical equations of the propagation of a Gaussian beam in inhomogeneous media described by the variations of the refractive index. The basic assumption under to get the analytical equations is to consider that the refractive index gradient is vertical and constant around the beam axis. The analytical equations that describe the propagation of a Gaussian beam were extended to model the propagation of an arbitrary field in a tropospheric medium with strong variations and inversions of the refractive index. This was done by coupling the analytical equations with the multibeam expansion procedure developped by Alexandre Chabory in his PhD thesis. The GBAR model was validated in tropospheric conditions, using refractive index grids from the WRF (Weather Research and Forecasting) mesoscale meteorological model. In the third and final phase, the GBAR model was used to simulate Radio Occultation data inversions. Tools exist to allow for interpretations of Radio Occultation data in order to estimate the physical properties of the atmosphere from measured phased, amplitude, Doppler shift and delay of GNSS signals transmitted between satellites orbiting around the Earth

Submitted by Vasti Diniz (vastijpa@hotmail.com) on 2017-09-18T12:28:21Z No. of bitstreams: 1 arquivototal.pdf: 2590482 bytes, checksum: a72ba5c8c44731f3cffe38777111a92d (MD5) / Made available in DSpace on 2017-09-18T12:28:21Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2590482 bytes, checksum: a72ba5c8c44731f3cffe38777111a92d (MD5) Previous issue date: 2011-04-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Aspects of the physics of nematic liquid crystals are studied in this thesis from the viewpoint of riemannian geometry through analogue models of gravitation. The topics chosen for study were: geometric and wave optics, elastic waves, hydrodynamics and heat conduction. The main analogue model used is based on the interpretation of Fermat’s principle as a process to obtain null geodesics, where the liquid crystalline material is seen as a riemannian manifold. This approach predicts that the metric effectively felt by the light ray depends on the configuration of molecules in the liquid crystal and on the parallel and perpendicular refractive indexes to the axis of symmetry of the liquid-cristal molecule. It is known that, for the particular case of the existence of topological defects within the material, effective metric similar to cosmological defects (like global monopoles and cosmic strings) are obtained. This thesis develops itself on the situation where there are topological defects of hedgehog type and (k = 1, c = 0) disclination type in the nematic phase of the liquid crystalline material. The first problem studied, as a review, deals with the wave optics, with respect to the light diffracted by the cited defects. Since plane waves of small wavelength have identical trajectories to light rays, the use of analog model is therefore justified. Thus, we show that light scattered by these defects generates a characteristic diffraction pattern, being the location given by an algebraic expression dependent on the parallel and perpendicular refractive indexes to the axis of symmetry of the molecule. We also show how theses patterns depend on the temperature of the material. The second studied problem deals with the geometrical optics and hydrodynamics of the nematic liquid crystals. From a molecular configuration similar to a (k = 1, c = 0) disclination, we let the material flow radially towards the axis of the defect. Then, using the hydrodynamic fact that velocity gradients in the material locally change the refractive index of the molecule, we find the velocity profile that must exist around the defect so that the metric actually experienced by light traveling in the plane perpendicular to the axis the defect is the Schwarzschild one in the equatorial plane, with the Schwarzschild radius interior to the object. We found that the absolute values of the velocity of liquid crystalline fluid can be order of a few meters per second, differing greatly from the values obtained by Gordon metric for an isotropic fluid under identical conditions. The third studied problem deals with the elastic oscillations in the presence of topological defects. Similarly to the first problem, the trajectory of the sound is obtained by an elastic version of Fermat’s principle and, then, compared with a null geodesic. We show how topological defects influence the sound trajectories and the sound diffracted by them. The fourth problem deals with the heat conduction in the vicinity of defects. Considering that the defects come from an addition or removal of portion of the material, letting the medium relaxes elastically, effective metric of the space disturbed by the defect are found, with expressions similar to those obtained by the analogous model based on Fermat’s principle. These metrics generate a modified thermal conductivity tensor, allowing the study of the temperature field in this situation. We show that, depending on the values of parallel and perpendicular thermal conductivity to the axis of symmetry of the molecule and on the defect in question, the temperature gradient can be accentuated or attenuated on the defect, allowing control of the response thermal temperature of the material, according to the presence of defects. Encouraging a greater understanding of the physics of liquid crystals and its use as a background in analogue models of gravity is the main theme of each analyzed problem. / Aspectos da física dos cristais líquidos nemáticos são estudados nesta tese do ponto de vista da geometria riemannina, por meio de modelos análogos de gravitação. Os tópicos escolhidos para estudo foram: óptica geométrica e ondulatória, ondas elásticas, hidrodinâmica e condução de calor. O principal modelo análogo empregado baseia-se na interpretação do princípio de Fermat como um processo de obtenção de geodésicas nulas, onde o material líquido-cristalino é visto como sendo uma variedade riemanniana. Esta abordagem prevê que a métrica efetivamente sentida pelo raio luminoso dependa da configuração das moléculas dentro do cristal líquido e dos índices de refração paralelo e perpendicular ao eixo de simetria da molécula líquido-cristalina. É sabido que, para o caso especial da existência de defeitos topológicos dentro do material, métricas efetivas semelhantes às de defeitos cosmológicos (como monopolos globais e cordas cósmicas) são obtidas. Esta tese desenrola-se sobre a situação onde existem defeitos topológicos do tipo ouriço e do tipo desclinação (k = 1, c = 0) na fase nemática do material líquido-cristalino. O primeiro problema estudado, em caráter de revisão, trata da óptica ondulatória, no que concerne a difração de luz pelos defeitos citados. Uma vez que ondas planas de comprimento de onda pequeno possuem trajetórias idênticas aos raios luminosos, o emprego do modelo análogo é justificado. Assim, mostramos que a luz espalhada por esses defeitos gera padrões de difração bem característicos, sendo a localização dada por expressão algébrica dependente dos índices de refração paralelo e perpendicular ao eixo de simetria da molécula líquido-cristalina. Também mostramos de que forma esses padrões dependem da temperatura do material. O segundo problema estudado trata da óptica geométrica e da hidrodinâmica dos cristais líquidos nemáticos. A partir de uma configuração de moléculas semelhantes à de uma desclinação (k = 1, c = 0), permitimos que o material flua radialmente na direção do eixo do defeito. Em seguida, fazendo uso do fato hidrodinâmico de que gradientes de velocidade no material modificam localmente os índices de refração da molécula, encontramos o perfil de velocidade que deve existir em torno do defeito para que a métrica efetivamente sentida pela luz, que viaja no plano perpendicular ao eixo do defeito, seja a de Schwarzschild no plano equatorial, com raio de Schwarzschild interior ao objeto. Encontramos que os valores absolutos da velocidade de fluido líquido-cristalino podem ser da ordem de alguns metros por segundo, diferindo enormemente dos valores obtidos pela métrica de Gordon para um fluido isotrópico em condições idênticas. O terceiro problema estudado aborda as oscilações elásticas na presença de defeitos. Semelhantemente ao primeiro problema, a trajetória do som é obtida por uma versão elástica do princípio de Fermat e, então, comparada com uma geodésica nula. Mostramos como defeitos topológicos influenciam nas trajetórias sonoras, assim como no som difratado por eles. O quarto problema trata da condução de calor na vizinhança de defeitos. Considerando que os defeitos são resultantes de uma adição ou remoção de porção de material, dando-se seguimento a uma relaxação elástica do meio, métricas efetivas do espaço perturbado pelo defeito são encontradas, com expressões semelhantes às obtidas pelo modelo análogo baseado no princípio de Fermat. Essas métricas geram um tensor condutividade térmica modificado, dando cabo ao estudo do campo de temperatura nessa situação. Mostramos que, dependendo dos valores da condutividade térmica perpendicular e paralela ao eixo de simetria da molécula líquido-cristalina e do defeito em questão, o gradiente de temperatura pode ser acentuado ou atenuado sobre o defeito, permitindo o controle da resposta térmica do material à temperatura, de acordo com a presença de defeitos. Suscitar um entendimento maior da física dos cristais líquidos e de seu emprego como background em modelos análogos de gravitação é o tema principal de cada um dos problemas analisados.

Acompanha: Ciência e arte na sala de aula e atividades / Este trabalho se propôs a repensar o ensino de alguns tópicos da óptica a partir das relações entre ciência e arte, entendidas como expressões humanas inseparáveis e instrumentos de compreensão do mundo. O referencial teórico possibilitou reflexões sobre o processo ensino-aprendizagem, sobre as relações entre Ciência a Arte como áreas do conhecimento humano construídas sócio historicamente e sobre o papel da criatividade e da imaginação no ensino de ciências. Baseando-se nestas relações, foi desenvolvida uma unidade didática alternativa para transposição de conceitos da óptica geométrica no ensino médio. A intervenção teve como concepção norteadora a pedagogia dialógico-problematizadora de Paulo Freire e se utilizou dos três momentos pedagógicos Estudo da Realidade, Organização do Conhecimento e Aplicação do Conhecimento, que são proposição dos pesquisadores J.A. Angotti e D. Delizoicov. Foi desenvolvida em três etapas e envolveu seis turmas de três colégios estaduais em Curitiba. O tema gerador foi a Arte Urbana (especialmente o grafite), presente no universo dos nossos educandos. A discussão gerada abordou o conceito de Ciência e a problematização foi feita utilizando-se a tela “An Experiment on a Bird in the Air Pump” (1766), de Joseph Wright of Derby. A estratégia de pesquisa foi do tipo observação participante e o tratamento de dados pelo método comparativo constante. Os dados foram obtidos no estilo cooperativo e a categoria geral definida para análise foi a das “Perspectivas tidas pelos sujeitos”, pois esta é consoante com a concepção freiriana de educação centrada nos sujeitos envolvidos e suas vivências. A pesquisa possibilitou concluir que são promissoras as possibilidades de incrementar o ensino de Física numa abordagem que busque reflexão sobre o papel da Ciência na construção coletiva e histórica do conhecimento, enriquecida pelas suas relações com a Arte; tanto na dimensão pedagógica quanto na acadêmica de pesquisa. / A summary of the stages of a qualitative research on Education, developed at UTFPR, Brazil, is presented. The purpose of this work is to rethink Education on some topics of Optics, on the basis of the relationship between Science and Art, which are understood here as inseparable human expressions and representations of the world. Based on this relationship, an alternative didactic unit was developed, aiming the transposition of concepts on Geometrical Optics in high school. The intervention was based on the dialogical and problem-posing approach due to Paulo Freire, and it was applied to six classes at three State high schools in Curitiba. The generative theme was Street Art, ubiquitous in the universe of students. The generated discussion involved the concept of Science and questioning was made using the painting “An Experiment on a Bird in the Air Pump”, by Joseph Wright of Derby (1766). The research strategy was participant observation, and data were processed by constant comparative method. The data were obtained from the cooperative style and the general category set for analysis was that of “Perspectives taken by subject”, since this is consonant with the Freirian conception for education centered on the involved subjects and their experiences. The research made it possible to conclude that the possibilities are promising to increase the teaching of Physics in an approach that aims to reflect on the role of science in building collective and historic knowledge, enriched by their relationships with art; both in pedagogical and academic research.

Acompanha: Ciência e arte na sala de aula e atividades / Este trabalho se propôs a repensar o ensino de alguns tópicos da óptica a partir das relações entre ciência e arte, entendidas como expressões humanas inseparáveis e instrumentos de compreensão do mundo. O referencial teórico possibilitou reflexões sobre o processo ensino-aprendizagem, sobre as relações entre Ciência a Arte como áreas do conhecimento humano construídas sócio historicamente e sobre o papel da criatividade e da imaginação no ensino de ciências. Baseando-se nestas relações, foi desenvolvida uma unidade didática alternativa para transposição de conceitos da óptica geométrica no ensino médio. A intervenção teve como concepção norteadora a pedagogia dialógico-problematizadora de Paulo Freire e se utilizou dos três momentos pedagógicos Estudo da Realidade, Organização do Conhecimento e Aplicação do Conhecimento, que são proposição dos pesquisadores J.A. Angotti e D. Delizoicov. Foi desenvolvida em três etapas e envolveu seis turmas de três colégios estaduais em Curitiba. O tema gerador foi a Arte Urbana (especialmente o grafite), presente no universo dos nossos educandos. A discussão gerada abordou o conceito de Ciência e a problematização foi feita utilizando-se a tela “An Experiment on a Bird in the Air Pump” (1766), de Joseph Wright of Derby. A estratégia de pesquisa foi do tipo observação participante e o tratamento de dados pelo método comparativo constante. Os dados foram obtidos no estilo cooperativo e a categoria geral definida para análise foi a das “Perspectivas tidas pelos sujeitos”, pois esta é consoante com a concepção freiriana de educação centrada nos sujeitos envolvidos e suas vivências. A pesquisa possibilitou concluir que são promissoras as possibilidades de incrementar o ensino de Física numa abordagem que busque reflexão sobre o papel da Ciência na construção coletiva e histórica do conhecimento, enriquecida pelas suas relações com a Arte; tanto na dimensão pedagógica quanto na acadêmica de pesquisa. / A summary of the stages of a qualitative research on Education, developed at UTFPR, Brazil, is presented. The purpose of this work is to rethink Education on some topics of Optics, on the basis of the relationship between Science and Art, which are understood here as inseparable human expressions and representations of the world. Based on this relationship, an alternative didactic unit was developed, aiming the transposition of concepts on Geometrical Optics in high school. The intervention was based on the dialogical and problem-posing approach due to Paulo Freire, and it was applied to six classes at three State high schools in Curitiba. The generative theme was Street Art, ubiquitous in the universe of students. The generated discussion involved the concept of Science and questioning was made using the painting “An Experiment on a Bird in the Air Pump”, by Joseph Wright of Derby (1766). The research strategy was participant observation, and data were processed by constant comparative method. The data were obtained from the cooperative style and the general category set for analysis was that of “Perspectives taken by subject”, since this is consonant with the Freirian conception for education centered on the involved subjects and their experiences. The research made it possible to conclude that the possibilities are promising to increase the teaching of Physics in an approach that aims to reflect on the role of science in building collective and historic knowledge, enriched by their relationships with art; both in pedagogical and academic research.

To investigate near-eld contributions for installed antennas, an in-house code iswritten to incorporate near-eld terms in Shooting and Bouncing Rays (SBR). SBRis a method where rays are launched toward an object and scatter using GeometricalOptics (GO). These rays induce currents on the object, from which the totalscattered eld can be found.To gauge the eect of near-eld terms, the in-house code can be set to excludenear-eld terms. Due to this characteristic, the method is named SBR Includingor Excluding Near-eld Terms (SIENT). The SIENT implementation is thoroughlydescribed. To make SIENT more exible, the code works with triangulated meshesof objects. Antennas are represented as near-eld sources, allowing complex antennasto be represented by simple surface currents. Further, some implementedoptimizations of SIENT are shown.To test the implemented method, SIENT is compared to a reference solution andcomparable commercial SBR solvers. It is shown that SIENT compares well to thecommercial options. Further, it is shown that the inclusion of near-eld terms actsas a small correction to the far-eld of the installed antenna. / För att undersöka närfältsbidrag för installerade antenner, har en kod skrivits för‌att ta med närfältstermer i Shooting Bouncing Rays (SBR). SBR är en metod där strålar (”rays”) skjuts mot ett object och sprids via Geometrisk Optik (GO). Dessa strålar inducerar strömmar på objectet, från vilka det totala sprida fältet kan hittas. För att undersöka bidraget från närfältstermer, så kan koden exkludera dessa. På grund av denna karaktär, kallas koden SBR Including or Excluding Near-field Terms (SIENT). Implementationen av SIENT beskrivs utförligt. För att göra SIENT mer flexibel, arbetar SIENT med triangulerade nät av objekt. Antenner representeras av närfältskällor, vilket låter komplexa antenner representeras med enkla yt-strömmar.Implementerade optimeringar av SIENT visas också.För att testa den implementerade metoden, jämförs SIENT med en referenslösning och jämförbara kommerciella SBR-lösare. Det visas att SIENT överensstämmer bra med kommerciella alternativ. Det visas också att närfältstermer agerar som enmindre korrektion till fjärrfältet av den installerade antennen.

Il existe au niveau d’interfaces séparant des milieux de constantes diélectriques de signes opposés des ondes électromagnétiques confinées à proximité de ces interfaces. On parle d’ondes de surface. C’est notamment le cas des métaux et des cristaux polaires : on parle alors de plasmons-polaritons de surface et de phonons-polaritons de surface respectivement. L’objectif de cette thèse est de revisiter certains aspects théoriques associés à ces ondes de surface.Dans un premier temps, en nous basant sur le formalisme de Green, nous donnons un moyen d’obtenir une expression du champ des ondes de surface sous forme de somme de modes. En présence de pertes, ces ondes ont nécessairement un vecteur d’onde ou une pulsation complexe. Nous donnons ainsi deux expressions de leur champ, correspondant à chacun de ces deux cas, et discutons de l’opportunité d’utiliser l’une ou l’autre de ces expressions.Nous posons par la suite les bases d’une optique de Fourier et d’une optique géométrique des ondes de surface. Nous montrons comment obtenir une équation de Helmholtz à deux dimensions pour les ondes de surface, un principe d’Huygens-Fresnel pour les ondes de surface, ainsi qu’une équation eikonale pour les ondes de surface, qui s’applique sous certaines hypothèses. Nous nous intéressons également à la superlentille proposée par Pendry, qui s’appuie sur les ondes de surface. Nous étudions notamment le fonctionnement de cette superlentille en régime impulsionnel, et montrons qu’en présence de pertes, il est possible d’obtenir une meilleure résolution avec certaines formes d’impulsion par rapport au régime harmonique, au prix d’une importante baisse de signal toutefois.Nous développons ensuite un traitement quantique des ondes de surface. Nous calculons au préalable une expression de leur énergie, et nous donnons une expression de leur hamiltonien et de leurs opérateurs champ. Sans pertes, nous montrons que le facteur de Purcell prédit par notre théorie quantique est rigoureusement égal au facteur de Purcell calculé avec des outils classiques. Nous comparons ensuite ce facteur de Purcell à celui calculé classiquement avec pertes, et montrons sur un exemple que les pertes peuvent être négligées dans de nombreux cas. Nous donnons enfin une expression des coefficients d’Einstein associés aux ondes de surface permettant d’étudier la dynamique de l’inversion de population d’un milieu fournissant un gain aux ondes de surface. Nous appliquons par la suite ce formalisme quantique à l’interaction électrons-phonons-polaritons de surface dans les puits quantiques, notamment leur interaction avec un mode de phonon du puits particulièrement confiné grâce à un effet de constante diélectrique proche de zéro (epsilon near zero, ENZ). / Interfaces between materials having opposite dielectric constants support electromagnetic waves confined close to these interfaces called surface waves. For metals and polar crystals, they are respectively called surface plasmon-polaritons and surface phonon-polaritons. The goal of this thesis is to revisit some theoretical aspects associated to these surface waves.Using the Green formalism, we derive an expression of the surface wave field as a sum of modes. With losses, these waves must have a complex wave vector or frequency. Thus we give two expressions of their field, for each of these cases, and discuss when each of these expressions should be used.We then give the basis of a surface wave Fourier optics and geometrical optics. We derive a 2D Helmholtz equation for surface waves, a Huygens-Fresnel principle for surface waves, and an eikonal equation for surface waves. We then take a look at Pendry’s superlens, in which surface waves play a major role. We study the behavior of the superlens in pulsed mode taking losses into account, and show that its resolution can be increased for some pulse shapes compared to the steady state, at the expense of a signal decay.We then develop a quantum treatment of surface waves. We first calculate their energy, and then give an expression of their hamiltonian and field operators. Without losses, we show that the Purcell factor given by our quantum theory is perfectly equal to the Purcell factor given by the classical theory. We then compare this Purcell factor to the lossy case on an example, and show that losses can often be neglected. We then derive the Einstein coefficients associated to surface wave emission and absorption, which allow studying the population inversion dynamics of a gain medium. We then use this quantum formalism to study the interaction between electrons and surface phonon-polaritons in quantum wells, particularly their interaction with a phonon mode which features high confinement thanks to an epsilon near zero (ENZ) effect.

Acompanha: Óptica, Joseph Wright e Edmodo / Esta dissertação investigou a compreensão dos conceitos introdutórios de Óptica mediados por uma plataforma de mídia social – Edmodo – utilizando a observação de telas do pintor inglês Joseph Wright (1734 – 1797). No século XVIII, na Inglaterra, marcado pela Revolução Industrial e o Iluminismo, as ciências físicas, químicas e biológicas tiveram um grande desenvolvimento. E é neste contexto que Joseph Wright produz uma série de pinturas de cenas noturnas representando questões científicas e industriais. Algumas de suas obras foram utilizadas para introduzir a Óptica em turmas de 2°ano do ensino médio de duas escolas estaduais do Paraná. O Ensino de Física atualmente demanda o uso de TIC e o Edmodo, que é uma plataforma de mídia social educativa, foi escolhida para mediar Arte e Física. Três atividades foram propostas: descrição de telas de Joseph Wright, questionário sobre o contexto histórico e fotografias contextualizadas. A abordagem da pesquisa foi qualitativa com procedimentos metodológicos segundo a pesquisa-ação. A coleta de dados consistiu na observação sistemática de atividades realizadas, da participação na plataforma e das interações provocadas com esta prática e, também na observação participante na apresentação das fotografias pelos estudantes. Concluiu-se que o conjunto Arte, História e Óptica consegue potencializar o ensino de conceitos de Óptica. Considerando a complexidade dos elementos envolvidos na pesquisa - as telas de Joseph Wright e o Edmodo - a postura dialógica nas práticas mostrou que os grupos de estudantes são potencialmente colaborativos quando estes elementos novos são introduzidos junto com os conteúdos da disciplina. Contudo, um tempo maior para esta ambientação com a TIC escolhida é necessário, visando estimular e ampliar a aprendizagem colaborativa. / This thesis investigated the understanding of introductory concepts of Optics mediated by a social media platform - Edmodo - and using the viewing screen of the english painter Joseph Wright (1734-1797). In the XVIII century in England, marked by the Industrial Revolution and the Enlightenment, the physical, chemical and biological sciences had a great development. It is in this context that Joseph Wright produces a number of night scenes paintings representing scientific and industrial issues. Some of his works were used to enter the Optics in classes of 2nd year of high school to two state schools of Paraná. The teaching of Physics currently requires the use of ICT and Edmodo, which is an educational social media platform, was chosen to mediate Art and Physics. Three activities are proposed: description of Joseph Wright screens, questionnaire on the historical context and contextual photographs. The research approach was qualitative and methodological procedures according to action research. Data collection consisted of systematic observation of activities performed, participation in the platform and interactions caused by this practice and also on participant observation in the presentation of photographs by students. It was concluded that all Art, History and Optics, can enhance the teaching optics concepts. Considering the complexity of the elements involved in the research - Joseph Wright’s screens and Edmodo - dialogical approach in practice has shown that student groups are potentially collaborative when these new elements are introduced along with the contents of the subject. However, a longer time for this setting with the chosen ICT is necessary to stimulate and expand the collaborative learning.

Acompanha: Óptica, Joseph Wright e Edmodo / Esta dissertação investigou a compreensão dos conceitos introdutórios de Óptica mediados por uma plataforma de mídia social – Edmodo – utilizando a observação de telas do pintor inglês Joseph Wright (1734 – 1797). No século XVIII, na Inglaterra, marcado pela Revolução Industrial e o Iluminismo, as ciências físicas, químicas e biológicas tiveram um grande desenvolvimento. E é neste contexto que Joseph Wright produz uma série de pinturas de cenas noturnas representando questões científicas e industriais. Algumas de suas obras foram utilizadas para introduzir a Óptica em turmas de 2°ano do ensino médio de duas escolas estaduais do Paraná. O Ensino de Física atualmente demanda o uso de TIC e o Edmodo, que é uma plataforma de mídia social educativa, foi escolhida para mediar Arte e Física. Três atividades foram propostas: descrição de telas de Joseph Wright, questionário sobre o contexto histórico e fotografias contextualizadas. A abordagem da pesquisa foi qualitativa com procedimentos metodológicos segundo a pesquisa-ação. A coleta de dados consistiu na observação sistemática de atividades realizadas, da participação na plataforma e das interações provocadas com esta prática e, também na observação participante na apresentação das fotografias pelos estudantes. Concluiu-se que o conjunto Arte, História e Óptica consegue potencializar o ensino de conceitos de Óptica. Considerando a complexidade dos elementos envolvidos na pesquisa - as telas de Joseph Wright e o Edmodo - a postura dialógica nas práticas mostrou que os grupos de estudantes são potencialmente colaborativos quando estes elementos novos são introduzidos junto com os conteúdos da disciplina. Contudo, um tempo maior para esta ambientação com a TIC escolhida é necessário, visando estimular e ampliar a aprendizagem colaborativa. / This thesis investigated the understanding of introductory concepts of Optics mediated by a social media platform - Edmodo - and using the viewing screen of the english painter Joseph Wright (1734-1797). In the XVIII century in England, marked by the Industrial Revolution and the Enlightenment, the physical, chemical and biological sciences had a great development. It is in this context that Joseph Wright produces a number of night scenes paintings representing scientific and industrial issues. Some of his works were used to enter the Optics in classes of 2nd year of high school to two state schools of Paraná. The teaching of Physics currently requires the use of ICT and Edmodo, which is an educational social media platform, was chosen to mediate Art and Physics. Three activities are proposed: description of Joseph Wright screens, questionnaire on the historical context and contextual photographs. The research approach was qualitative and methodological procedures according to action research. Data collection consisted of systematic observation of activities performed, participation in the platform and interactions caused by this practice and also on participant observation in the presentation of photographs by students. It was concluded that all Art, History and Optics, can enhance the teaching optics concepts. Considering the complexity of the elements involved in the research - Joseph Wright’s screens and Edmodo - dialogical approach in practice has shown that student groups are potentially collaborative when these new elements are introduced along with the contents of the subject. However, a longer time for this setting with the chosen ICT is necessary to stimulate and expand the collaborative learning.

L'évaluation de la démarche humaine est l'une des composantes essentielles dans les soins de santé. Les systèmes à base de marqueurs avec plusieurs caméras sont largement utilisés pour faire cette analyse. Cependant, ces systèmes nécessitent généralement des équipements spécifiques à prix élevé et/ou des moyens de calcul intensif. Afin de réduire le coût de ces dispositifs, nous nous concentrons sur un système d'analyse de la marche qui utilise une seule caméra de profondeur. Le principe de notre travail est similaire aux systèmes multi-caméras, mais l'ensemble de caméras est remplacé par un seul capteur de profondeur et des miroirs. Chaque miroir dans notre configuration joue le rôle d'une caméra qui capture la scène sous un point de vue différent. Puisque nous n'utilisons qu'une seule caméra, il est ainsi possible d'éviter l'étape de synchronisation et également de réduire le coût de l'appareillage. Notre thèse peut être divisée en deux sections: reconstruction 3D et analyse de la marche. Le résultat de la première section est utilisé comme entrée de la seconde. Notre système pour la reconstruction 3D est constitué d'une caméra de profondeur et deux miroirs. Deux types de capteurs de profondeur, qui se distinguent sur la base du mécanisme d'estimation de profondeur, ont été utilisés dans nos travaux. Avec la technique de lumière structurée (SL) intégrée dans le capteur Kinect 1, nous effectuons la reconstruction 3D à partir des principes de l'optique géométrique. Pour augmenter le niveau des détails du modèle reconstruit en 3D, la Kinect 2 qui estime la profondeur par temps de vol (ToF), est ensuite utilisée pour l'acquisition d'images. Cependant, en raison de réflections multiples sur les miroirs, il se produit une distorsion de la profondeur dans notre système. Nous proposons donc une approche simple pour réduire cette distorsion avant d'appliquer les techniques d'optique géométrique pour reconstruire un nuage de points de l'objet 3D. Pour l'analyse de la démarche, nous proposons diverses alternatives centrées sur la normalité de la marche et la mesure de sa symétrie. Cela devrait être utile lors de traitements cliniques pour évaluer, par exemple, la récupération du patient après une intervention chirurgicale. Ces méthodes se composent d'approches avec ou sans modèle qui ont des inconvénients et avantages différents. Dans cette thèse, nous présentons 3 méthodes qui traitent directement les nuages de points reconstruits dans la section précédente. La première utilise la corrélation croisée des demi-corps gauche et droit pour évaluer la symétrie de la démarche, tandis que les deux autres methodes utilisent des autoencodeurs issus de l'apprentissage profond pour mesurer la normalité de la démarche. / The problem of assessing human gaits has received a great attention in the literature since gait analysis is one of key components in healthcare. Marker-based and multi-camera systems are widely employed to deal with this problem. However, such systems usually require specific equipments with high price and/or high computational cost. In order to reduce the cost of devices, we focus on a system of gait analysis which employs only one depth sensor. The principle of our work is similar to multi-camera systems, but the collection of cameras is replaced by one depth sensor and mirrors. Each mirror in our setup plays the role of a camera which captures the scene at a different viewpoint. Since we use only one camera, the step of synchronization can thus be avoided and the cost of devices is also reduced. Our studies can be separated into two categories: 3D reconstruction and gait analysis. The result of the former category is used as the input of the latter one. Our system for 3D reconstruction is built with a depth camera and two mirrors. Two types of depth sensor, which are distinguished based on the scheme of depth estimation, have been employed in our works. With the structured light (SL) technique integrated into the Kinect 1, we perform the 3D reconstruction based on geometrical optics. In order to increase the level of details of the 3D reconstructed model, the Kinect 2 with time-of-flight (ToF) depth measurement is used for image acquisition instead of the previous generation. However, due to multiple reflections on the mirrors, depth distortion occurs in our setup. We thus propose a simple approach for reducing such distortion before applying geometrical optics to reconstruct a point cloud of the 3D object. For the task of gait analysis, we propose various alternative approaches focusing on the problem of gait normality/symmetry measurement. They are expected to be useful for clinical treatments such as monitoring patient's recovery after surgery. These methods consist of model-free and model-based approaches that have different cons and pros. In this dissertation, we present 3 methods that directly process point clouds reconstructed from the previous work. The first one uses cross-correlation of left and right half-bodies to assess gait symmetry while the other ones employ deep auto-encoders to measure gait normality.