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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Electromagnétisme non-maxwellien en astrophysique et applications spatiales à très basses fréquences / Non-Maxwellian electromagnetism in astrophysics and in space applications at low radio frequencies

Bonetti, Luca 21 December 2016 (has links)
L’univers est largement observé avec les signaux électromagnétiques – supposés maxwelliens – bien que la fenêtre d’onde gravitationnelle vient juste d’être ouverte. La cosmologie est depuis longtemps confrontée à un univers à 96% noir et inconnu. Donc, il est pertinent pour la physique fondamentale de débuter une vérification théorique et expérimentale de l’électromagnétisme et de son messager, le photon. La thèse aborde les théories non-maxwelliennes, en se focalisant sur les effets vérifiables. Nous traitons d’une série d’applications et évaluons le degré d’utilité des théories électromagnétiques alternatives. Nous revoyons les théories les plus importantes, qu’elles soient non-linéaires ou massives. Pour la première catégorie, pour l’analyse de la force propre, nous considérons la radiation d’une charge de Born-Infeld uniformément accélérée ; dans la théorie d’Heisenberg-Euler, nous trouvons un décalage en fréquence induit par un dipôle magnétique surcritique, associé à un magnétar. Le photon étant la seule particule sans masse dans le Modèle Standard (MS), nous explorons les extensions de MS. En effet, pour la catégorie massive, dans un contexte supersymétrique, nous trouvons des comportements non-maxwelliens survenant dans des cas paires et impairs de symétrie CPT (Charge-Parity-Time Reversal) : soit une propagation à vitesse sous lumineuse ou un comportement massif dispersif proportionnel au vecteur qui provoque la rupture de la symétrie de Lorentz. Plus loin, nous déterminons une limite supérieure de la masse de 3.2 x 10-50 kg en analysant les Fast Radio Bursts. Les différences des temps d’arrivée d’un photon massif (à la de Broglie-Proca) s’expriment comme l’inverse de la fréquence au carrée, comme les photons traversant un plasma.De là provient notre intérêt pour la radioastronomie à basse fréquence au sol ou dans l’espace. Un domaine inexploré cachant des pulsars se situe en-dessous de 15 MHz, et sera accessible par un essaim de nano satellites. / The universe is largely observed with electromagnetic signals – supposedly Maxwellian – though thegravitational wave window was just unbarred. Meanwhile, cosmology is since long confronted with anuniverse for 96% dark and unknown. Thus, it is pertinent for fundamental physics to start a theoretical andexperimental verification of electromagnetism, and its photon messenger. The thesis discusses non-Maxwellian theories, focusing on testable effects. We deal with a range of applications and assess howalternative electromagnetic theories are helpful. We revise the most notable theories, either non-linear ormassive. In the former class, for analysis of the self-force, we consider the radiation of an uniformlyaccelerating Born-Infeld charge; in the Heisenberg-Euler theory, we find a frequency shift induced by anovercritical magnetic dipole, associated to a magnetar. Being the photon the only massless particle in theStandard Model (SM), we explore SM extensions. Indeed for the massive class, in a supersymmetriccontext, we find non-Maxwellian behaviors arising in even and odd cases of Charge-Parity-Time Reversal(CPT) symmetry: either subluminal propagation or massive dispersive behavior proportional to the Lorentzsymmetry breaking vector. Further on, we determine an upper mass limit of 3.2 x 10-50 kg by analyzing FastRadio Bursts. Massive (à la de Broglie-Proca) photon arrival time delays go with the inverse of frequencysquared, as photons passing through plasma. Thereby, our interest for low frequency radio-astronomy onground or in space. An unexplored domain hiding pulsars lies below 15 MHz, and it will be accessible by aswarm of nano-satellites.
192

Some problems in field theory

Smith, B. G. January 1964 (has links)
No description available.
193

Simulation électromagnétique utilisant une méthode modale de décomposition en ondelettes / Electromagnetic modeling using modal method and wavelet expansion

Armeanu, Ana 17 June 2011 (has links)
La scattéromètrie requiert le calcul de la réponse optique de structures périodiques. Parmi les méthodes numériques de calcul électromagnétique de la diffraction par des réseaux, la méthode la plus couramment utilisée est la Méthode Modale de Fourier (FMM). Celle cis'avère peu efficace pour la caractérisation de structures très isolées ou très denses et peut même ne pas marcher du tout. L'objectif de cette thèse est de dépasser les limitations de la FMM. Nous restons dans le cadre des méthodes modales mais nous explorons de nouvelles voies en utilisant des bases de développement différentes qui ne présentent pas les inconvénients des bases de Fourier. Tout d'abord, nous avons introduit les fonctions B-spline qui sont le premier pas vers l'analyse multi-résolution avec les ondelettes splines. Nous avons formulé le problème de la diffraction par un réseau 1D comme un problème aux valeurs propres que nous avons résolu numériquement à l'aide de la méthode de Galerkin. Nous avons étudié en détail l'importance de la discrétisation par rapport aux discontinuités de la fonction permittivité. Ensuite, nous avons introduit les ondelettes et l'analyse à plusieurs niveaux de détails pour le problème de diffraction. La thèse contient une palette variée d'exemples numériques concernant des réseaux diélectriques et métalliques. Nous avons comparé soigneusement la convergence de nos méthodes avec celle d?autres méthodes, notamment avec la FMM. Nous avons montré que l'analyse multirésolution permet de traiter des cas pour lesquels la FMM échoue. / The scatterometry requires calculating the optical response of periodic structures. Among the numerical methods for calculating electromagnetic diffraction by gratings, the most commonly used is the Fourier Modal Method (FMM). This seems to be ineffective for characterizing structures very isolated or very dense and can even fail. The objective of this thesis is to overcome the limitations of the FMM. We remain within the framework of modal methods but we are exploring new ways of using different bases of development that do not have the drawbacks of Fourier bases. First, we introduced the B-spline functions which are the first step towards multi-resolution analysis with wavelet splines. We formulated the problem of diffraction by a 1D grating as an eigenvalue problem that we solved numerically using the Galerkin method. We studied in detail the importance of the discretization compared to the discontinuities of permittivity function. Then we introduced the wavelet analysis at multiple levels of detail for the diffraction problem. The thesis contains a diversity of numerical examples concerning dielectric and metal gratings. We have carefully compared the convergence of our methods with that of other methods, especially with the FMM. We showed that multiresolution analysis can deal with cases where the FMM fails.
194

Uso de técnicas de realidade aumentada no processo de ensino–aprendizagem de eletromagnetismo

Macedo, Suzana da Hora January 2011 (has links)
Este estudo tem como objetivo melhorar o processo de ensino-aprendizagem dos conceitos de Eletromagnetismo usando Realidade Aumentada (RA). Eletromagnetismo é a base científica para a compreensão do princípio de funcionamento das máquinas elétricas rotativas. No entanto, verificou-se através de um estudo preliminar que existem dificuldades no processo de ensino-aprendizagem de Eletromagnetismo e que estas dificuldades estão concentradas basicamente em dois fatores: tanto na visualização da representação correta do campo magnético quanto na base matemática para trabalhar com esses conceitos, os quais permitiriam a aquisição de novos conceitos na área de Eletromagnetismo. O estudo preliminar foi realizado através de questionários aplicados aos alunos e aos professores da disciplina Eletricidade, que aborda os referidos conceitos. O resultado do estudo revelou que 85% dos professores percebem as dificuldades dos alunos em aprender e, confirmada esta percepção pelos próprios alunos, dos quais apenas 39,5% demonstraram ter aprendido estes conceitos. Este trabalho foi baseado na teoria da Aprendizagem Significativa, que, de acordo com Ausubel, ocorre quando um conceito está relacionado de forma significativa e não arbitrária, com conceitos preexistentes na estrutura cognitiva do indivíduo. Na busca de nivelar os alunos para que todos tivessem os subsunçores necessários que permitissem melhorar o processo de ensino-aprendizagem de novos conceitos, os subsunçores de outros conceitos foram definidos e desenvolvidos três Objetos de Aprendizagem. A descoberta dos subsunçores e a ordem do uso dos Objetos de Aprendizagem permitiram melhorar o processo de ensino-aprendizagem de novos conceitos com o objetivo de atingir o conceito principal de campo girante fundamental no processo de ensinoaprendizagem de Máquinas Elétricas. Neste trabalho, foram utilizados três Objetos de Aprendizagem como ferramentas no processo de ensino-aprendizagem de conceitos de Eletromagnetismo para se superar o obstáculo da visualização dos campos magnéticos. Estes Objetos de Aprendizagem foram testados com os alunos dos cursos técnicos do IFF – campus Itaperuna, onde o aluno pode visualizar e interagir com os mesmos. A partir dos resultados obtidos com a interação dos alunos com os Objetos de Aprendizagem foi possível fazer análises e avaliações que permitiram concluir o presente trabalho. / This study aims to improve teaching-learning process of the concepts of Electromagnetism using Augmented Reality (AR). Electromagnetism is the scientific bases for understanding the operating principle of rotating electrical machines. However, it was found through a preliminary study, that there are difficulties in the teaching-learning process of Electromagnetism and these difficulties are concentrated primarily on two factors: the correct view of the representation of the magnetic field and in the mathematical basis to work with these concepts, concepts that allow the acquisition of new concepts in Electromagnetism area. The preliminary study was realized through questionnaires to students and professors of Electricity that addresses these concepts. The study results revealed that 85% of teachers perceive students’ difficulties in learning and confirming this perception by the students, where only 39,5% of these demonstrate to have learned these concepts. This work was based on the Meaningful Learning theory, which, according to Ausubel, occurs when a concept is related significantly and not arbitrary, with pre-existing concepts in cognitive structure of the individual. Aiming to put all students at the same level, there was necessary subsumers for improving the teaching-learning of new concepts, another subsumers about other concepts were defined and were developed three Learning Objects. The discovery of subsumers and the order the use of the Learning Objects allowed to improve the teaching-learning process of new concepts in order to achieve the main concept of the rotating fields, key in the teaching-learning process of Electrical Machines. In this study, there were employed three Learning Objects as tools in the teaching-learning process of Electromagnetism concepts to overcome the obstacle of the visualization of the magnetic fields. These Learning Objects have been tested with students of technical courses of IFF – campus Itaperuna, where students could view and interact with them. From the results, analysis and evaluations were made to complete the work.
195

Réduction de modèles issus de la méthode PEEC pour la modélisation électromagnétique des interconnexions électriques / Reduced PEEC model for electromagnetism modelisation of eletrical interconnections

Nguyen, Trung Son 22 October 2012 (has links)
Le sujet de cette thèse traite de l'amélioration de la méthode PEEC inductive (permettant une modélisation des interconnexions électriques d'un point de vue électromagnétique basse fréquence) en employant une méthode de compression matricielle FMM. L'introduction de ces compressions entraîne des restrictions concernant les opérations algébriques autorisées, seule les opérations de type produit matrice - vecteur sont permises. L'objectif était de proposer des méthodes pour déterminer : Les courants en tout point du dispositif Des impédances équivalentes entre différents ports d'entrées-sorties. Le premier point a pu être traité en mettant en place une méthode originale de recherche d'un jeu d'équations indépendantes ainsi qu'un préconditionneur spécifique dans la phase de résolution compatible avec les méthodes de compression matricielle. Le second point a nécessité l'utilisation de méthode de réduction d'ordre à base de sous espace de Krylov afin de construire un développement limité des jeux d'impédance recherché. Ensuite, nous avons mis en place une technique de synthèse de circuit afin d'obtenir un circuit électrique simple permettant de modéliser le comportement du dispositif avec de simples éléments de type résistance, inductance (non couplée) et capacité. Cette démarche permet l'utilisation dans tous les simulateurs temporels et ainsi permet d'avoir une vision système légère du dispositif d'interconnexion électrique. / This thesis deals with the improvement of the inductive PEEC method (for modelling electrical interconnections of low frequency) using the matrix compression Fast Multipole Method (FMM). The introduction of FMM leads to only algebraic operation of type matrix - vector product is permitted. The objective of this thesis was to propose some methods to determine: • Currents at any point of the device • The equivalent impedances between different input-output ports. The first point has been treated by introducing a novel method to determine a set of independent equations. The choice of iterative methods in solving linear system imposed on the establishment of a specific preconditioner compatible with matrix compression methods. The second point require to describe the Kirchoff law in the form of state space equation and to use model order reduction method based on Krylov subspace to compute Taylor series of impedance matrix. Once again, all the steps are necessary to be taked into account the use of matrix compression method FMM. Following our order reduction method, we implemented a circuit synthesis technique to obtain a simple electrical circuit which conserve the behavior of the device by simple elements like resistance, inductance (uncoupled) and capacity. This approach allows the reuse of reduction model in all time domain simulation software. For global system, it provides also a light model of electrical interconnection device.
196

Uso de técnicas de realidade aumentada no processo de ensino–aprendizagem de eletromagnetismo

Macedo, Suzana da Hora January 2011 (has links)
Este estudo tem como objetivo melhorar o processo de ensino-aprendizagem dos conceitos de Eletromagnetismo usando Realidade Aumentada (RA). Eletromagnetismo é a base científica para a compreensão do princípio de funcionamento das máquinas elétricas rotativas. No entanto, verificou-se através de um estudo preliminar que existem dificuldades no processo de ensino-aprendizagem de Eletromagnetismo e que estas dificuldades estão concentradas basicamente em dois fatores: tanto na visualização da representação correta do campo magnético quanto na base matemática para trabalhar com esses conceitos, os quais permitiriam a aquisição de novos conceitos na área de Eletromagnetismo. O estudo preliminar foi realizado através de questionários aplicados aos alunos e aos professores da disciplina Eletricidade, que aborda os referidos conceitos. O resultado do estudo revelou que 85% dos professores percebem as dificuldades dos alunos em aprender e, confirmada esta percepção pelos próprios alunos, dos quais apenas 39,5% demonstraram ter aprendido estes conceitos. Este trabalho foi baseado na teoria da Aprendizagem Significativa, que, de acordo com Ausubel, ocorre quando um conceito está relacionado de forma significativa e não arbitrária, com conceitos preexistentes na estrutura cognitiva do indivíduo. Na busca de nivelar os alunos para que todos tivessem os subsunçores necessários que permitissem melhorar o processo de ensino-aprendizagem de novos conceitos, os subsunçores de outros conceitos foram definidos e desenvolvidos três Objetos de Aprendizagem. A descoberta dos subsunçores e a ordem do uso dos Objetos de Aprendizagem permitiram melhorar o processo de ensino-aprendizagem de novos conceitos com o objetivo de atingir o conceito principal de campo girante fundamental no processo de ensinoaprendizagem de Máquinas Elétricas. Neste trabalho, foram utilizados três Objetos de Aprendizagem como ferramentas no processo de ensino-aprendizagem de conceitos de Eletromagnetismo para se superar o obstáculo da visualização dos campos magnéticos. Estes Objetos de Aprendizagem foram testados com os alunos dos cursos técnicos do IFF – campus Itaperuna, onde o aluno pode visualizar e interagir com os mesmos. A partir dos resultados obtidos com a interação dos alunos com os Objetos de Aprendizagem foi possível fazer análises e avaliações que permitiram concluir o presente trabalho. / This study aims to improve teaching-learning process of the concepts of Electromagnetism using Augmented Reality (AR). Electromagnetism is the scientific bases for understanding the operating principle of rotating electrical machines. However, it was found through a preliminary study, that there are difficulties in the teaching-learning process of Electromagnetism and these difficulties are concentrated primarily on two factors: the correct view of the representation of the magnetic field and in the mathematical basis to work with these concepts, concepts that allow the acquisition of new concepts in Electromagnetism area. The preliminary study was realized through questionnaires to students and professors of Electricity that addresses these concepts. The study results revealed that 85% of teachers perceive students’ difficulties in learning and confirming this perception by the students, where only 39,5% of these demonstrate to have learned these concepts. This work was based on the Meaningful Learning theory, which, according to Ausubel, occurs when a concept is related significantly and not arbitrary, with pre-existing concepts in cognitive structure of the individual. Aiming to put all students at the same level, there was necessary subsumers for improving the teaching-learning of new concepts, another subsumers about other concepts were defined and were developed three Learning Objects. The discovery of subsumers and the order the use of the Learning Objects allowed to improve the teaching-learning process of new concepts in order to achieve the main concept of the rotating fields, key in the teaching-learning process of Electrical Machines. In this study, there were employed three Learning Objects as tools in the teaching-learning process of Electromagnetism concepts to overcome the obstacle of the visualization of the magnetic fields. These Learning Objects have been tested with students of technical courses of IFF – campus Itaperuna, where students could view and interact with them. From the results, analysis and evaluations were made to complete the work.
197

Uso de técnicas de realidade aumentada no processo de ensino–aprendizagem de eletromagnetismo

Macedo, Suzana da Hora January 2011 (has links)
Este estudo tem como objetivo melhorar o processo de ensino-aprendizagem dos conceitos de Eletromagnetismo usando Realidade Aumentada (RA). Eletromagnetismo é a base científica para a compreensão do princípio de funcionamento das máquinas elétricas rotativas. No entanto, verificou-se através de um estudo preliminar que existem dificuldades no processo de ensino-aprendizagem de Eletromagnetismo e que estas dificuldades estão concentradas basicamente em dois fatores: tanto na visualização da representação correta do campo magnético quanto na base matemática para trabalhar com esses conceitos, os quais permitiriam a aquisição de novos conceitos na área de Eletromagnetismo. O estudo preliminar foi realizado através de questionários aplicados aos alunos e aos professores da disciplina Eletricidade, que aborda os referidos conceitos. O resultado do estudo revelou que 85% dos professores percebem as dificuldades dos alunos em aprender e, confirmada esta percepção pelos próprios alunos, dos quais apenas 39,5% demonstraram ter aprendido estes conceitos. Este trabalho foi baseado na teoria da Aprendizagem Significativa, que, de acordo com Ausubel, ocorre quando um conceito está relacionado de forma significativa e não arbitrária, com conceitos preexistentes na estrutura cognitiva do indivíduo. Na busca de nivelar os alunos para que todos tivessem os subsunçores necessários que permitissem melhorar o processo de ensino-aprendizagem de novos conceitos, os subsunçores de outros conceitos foram definidos e desenvolvidos três Objetos de Aprendizagem. A descoberta dos subsunçores e a ordem do uso dos Objetos de Aprendizagem permitiram melhorar o processo de ensino-aprendizagem de novos conceitos com o objetivo de atingir o conceito principal de campo girante fundamental no processo de ensinoaprendizagem de Máquinas Elétricas. Neste trabalho, foram utilizados três Objetos de Aprendizagem como ferramentas no processo de ensino-aprendizagem de conceitos de Eletromagnetismo para se superar o obstáculo da visualização dos campos magnéticos. Estes Objetos de Aprendizagem foram testados com os alunos dos cursos técnicos do IFF – campus Itaperuna, onde o aluno pode visualizar e interagir com os mesmos. A partir dos resultados obtidos com a interação dos alunos com os Objetos de Aprendizagem foi possível fazer análises e avaliações que permitiram concluir o presente trabalho. / This study aims to improve teaching-learning process of the concepts of Electromagnetism using Augmented Reality (AR). Electromagnetism is the scientific bases for understanding the operating principle of rotating electrical machines. However, it was found through a preliminary study, that there are difficulties in the teaching-learning process of Electromagnetism and these difficulties are concentrated primarily on two factors: the correct view of the representation of the magnetic field and in the mathematical basis to work with these concepts, concepts that allow the acquisition of new concepts in Electromagnetism area. The preliminary study was realized through questionnaires to students and professors of Electricity that addresses these concepts. The study results revealed that 85% of teachers perceive students’ difficulties in learning and confirming this perception by the students, where only 39,5% of these demonstrate to have learned these concepts. This work was based on the Meaningful Learning theory, which, according to Ausubel, occurs when a concept is related significantly and not arbitrary, with pre-existing concepts in cognitive structure of the individual. Aiming to put all students at the same level, there was necessary subsumers for improving the teaching-learning of new concepts, another subsumers about other concepts were defined and were developed three Learning Objects. The discovery of subsumers and the order the use of the Learning Objects allowed to improve the teaching-learning process of new concepts in order to achieve the main concept of the rotating fields, key in the teaching-learning process of Electrical Machines. In this study, there were employed three Learning Objects as tools in the teaching-learning process of Electromagnetism concepts to overcome the obstacle of the visualization of the magnetic fields. These Learning Objects have been tested with students of technical courses of IFF – campus Itaperuna, where students could view and interact with them. From the results, analysis and evaluations were made to complete the work.
198

Nouveau système de contrôle Radiofréquence de micro-algues pour la santé et le bien-être / New Radiofrequency Monitoring of microalgae cultivation for health and welfare

Zhou, Xi 06 December 2016 (has links)
Le développement des produits à base de polysaccharides issus de microalgues implique une étude poussée des voies biotechnologiques de culture. Afin d'optimiser ces nouveaux produits dès la formation des microalgues, un nouveau système de contrôle non-destructif en ligne et sans contact a été développé dans le cadre de cette thèse. Il s'appuie sur la mesure par induction des propriétés diélectriques (conductivité et permittivité) dans le domaine des radiofréquences (1-400MHz). Ce document montre, qu'à l'échelle d'investigation correspondante, il est possible de suivre aussi bien l'évolution du milieu de culture que la formation d'exopolymères via la mesure de la permittivité complexe de ces matériaux. La preuve de concept a nécessité la mise au point d'un circuit résonant bas coût particulièrement sensible, utilisé en émission-réception, et la résolution théorique et expérimentale d'un problème inverse adapté aux champs proches. Ce système implanté dans un photobioréacteur prototype a permis d'extraire l'évolution de grandeurs caractéristiques propres au suivi de culture de microalgues. Cette thèse s'inscrit dans un projet collaboratif plus large de valorisation d'actifs issus de microalgues avec les sociétés Phycosource, Pronovalg, Bio-EC, et LVMH dans le cadre d'un FUI. / The development of products based on polysaccharides from microalgae involves extensive study of biotechnological ways of cultivation. In order to optimize these new products, from the formation of microalgae, a new non-destructive testing system online and without contact has been developed as part of this thesis. It is based on the measurement by induction of dielectric properties (permittivity and conductivity) in the field of radio frequency (1-400MHz). This document shows that inside the corresponding scale of investigation, it is possible to follow both the evolution of the culture medium and the exopolymer formation, via the measurement of complex permittivity of these materials. The proof of concept, required the development of a resonant low cost system particularly sensitive, used as a transceiver, and theoretical and experimental solution of an inverse problem in near fields. This system that operates in a photobioreactor prototype, was used to extract the evolution of characteristics variables of microalgae cultivation. This thesis is part of a larger collaborative project valuation of assets derived from microalgae with Phycosource companies Pronovalg, Bio-EC, and LVMH as part of a FUI.
199

Modélisation électromagnétique rapide de problèmes multi-échelles incluant une partie variable - Application à la dosimétrie numérique et au couplage entre antennes / Fast electromagnetic modeling of multiscale problems including a variable part - Application to numerical dosimetry and antennas coupling

Guelilia, Zakaria 21 October 2014 (has links)
La simulation numérique est un outil indispensable pour la résolution de problèmes électromagnétiques. Le temps de calcul ainsi que la précision des résultats dépendent du niveau de description utilisé et des dimensions électriques du problème analysé. Dans le cas de figure où il est nécessaire de modéliser un environnement électriquement grand, l'emploi de méthodes classiques comme la méthode des différences finies dans le domaine temporel (FDTD) se heurte à des difficultés en termes de temps de simulation. Cet aspect devient particulièrement problématique quand l'analyse doit être menée pour plusieurs valeurs d'un ou plusieurs paramètres définissant le problème étudié. Face à cette variabilité et afin d'éviter la multiplication de simulations coûteuses, Il est nécessaire d'opter pour des méthodes appropriées. Les travaux de cette thèse sont consacrés au développement d'une nouvelle approche permettant de résoudre de manière efficace l'aspect variable rencontré dans un problème multiéchelle. Cette nouvelle méthode issue de l'association de la FDTD à Grille Double (DG-FDTD) avec un modèle de substitution se nomme la MM-DG-FDTD (Macro-Modèle basé sur la DG-FDTD). L'emploi de la DG-FDTD vise à traiter l'aspect multi-échelle en divisant le problème étudié en sous-volumes FDTD possédant chacun ses propres paramètres de simulation. L'utilisation d'un modèle de substitution rapide construit en peu de simulations électromagnétiques permet de remplacer rigoureusement et rapidement la dernière simulation de la DGFDTD. Après avoir validé le bon fonctionnement du modèle de substitution sur des cas simples, une utilisation de la MM-DGFDTD est effectuée sur deux applications inscrites dans deux contextes : la dosimétrie numérique et le couplage entre antennes. La première propose d'estimer la valeur du champ électrique à l'intérieur de l'oeil gauche d'un modèle de corps humain. Ce dernier est soumis au rayonnement électromagnétique d'une antenne localisée sur un véhicule. Cette étude est effectuée pour un grand nombre de positions du corps autour du véhicule. La seconde application consiste à évaluer la valeur du coefficient de transmission entre deux antennes ULB (Ultra-Large Bande). La position de l'antenne de réception évolue au sein d'un grand environnement. Pour ces deux études, la MM-DG-FDTD montre sa capacité à donner des résultats rapides et précis en comparaison d'une utilisation classique de la DG-FDTD. / Numerical modelling is an essential tool for solving electromagnetic problems. The computation time and the accuracy of the results depend on the description level used and electrical dimensions of the analyzed problem. When it is necessary to model an electrically large environment, the use of conventional methods such as the finite difference time domain (FDTD) face difficulties in terms of simulation time. This becomes particularly problematic when the analysis must be carried out for several values of one or more parameters defining the studied problem. Considering this variability aspect and in order to avoid multiplication of costly simulations, it is necessary to choose suitable methods. This thesis aims to develop a new approach to solve effectively the variable feature encountered in some multi-scale problems. This new method called the MM-DG-FDTD (MacroModel based Dual Grid-FDTD) results from the association of the Dual Grid- FDTD (DG-FDTD) method with a substitution model. The use of the DG-FDTD permits to treat multiscale aspect dividing the studied problem into FDTD sub-volumes. Each step has its own simulation parameters. The fast substitution model built in few electromagnetic simulations replaces in a rigorous and efficient way the last expensive DG-FDTD simulation. The proper operation of the substitution model is firstly validated using simple cases. Next, a use of the MM-DG-FDTD is performed on two applications belonging to two contexts: numerical dosimetry and antennas coupling. The first one proposes to estimate the value of the electric field inside the left eye of a human body model. It receives electromagnetic radiation from an antenna located onboard a vehicle. This study is carried out for a large number of positions of the body around the vehicle. The second application is to assess the value of the transmission coefficient between two UWB (Utra-Wide Band) antennas. The position of the receiving antenna changes in a large environment. For both studies, MM-DG-FDTD shows its ability to give fast and accurate results compared to a classic use of the DG-FDTD.
200

Electromagnetic aftereffects of near-death experiences.

Nouri, Farnoosh Massoudian 08 1900 (has links)
The purpose of this quantitative study was first to investigate the comparative incidence of electromagnetic aftereffects (EMEs) during the past year among near-death experiencers (NDErs), people who experienced a close brush with death without an NDE (CBrs), and people who reported never having experienced a close brush with death (LCErs). The second purpose was to investigate a possible change in EME incidence among the three groups before and after a critical life event. The third purpose was to investigate the relationship between the reported overall depth and specific components of the subjective experiences of people who have had a close brush with death -- NDErs and CBrs -- and their reported incidence of EMEs. I used the Near-Death Experience Scale (Greyson, 1983), and developed the Close Brush with Death Question form, Life Changing Event Question form, and Electromagnetic Effects Questionnaire for this study. The final sample included 36 NDErs, 20 CBrs, and 46 LCErs. The results of this study firmly supported more reported problems with EM devices experienced by NDErs compared to CBrs or LCErs. Especially with respect to EM devices such as lights and cell phones, as well as the emotional state of individuals affecting EM devices, this study showed more reports of problems with these devices between before and after NDEs for NDErs compared to before and after a life changing event for LCErs. Moreover, findings of this study showed a correlation between the depth of NDEs and EMEs. This study has important implications for counselors working with NDErs. Findings from this study show that NDErs have a strong possibility of experiencing electromagnetic interferences when close to electromagnetic devices such as cell phones, computers, lights, and watches after their NDEs. This phenomenon can be a stressor in the lives of NDErs and their families and friends. As some participants in this study indicated, information about EMEs can reduce NDErs' stress. Thus, counselors can use information from this study to psychoeducate their NDEr clients and work with them to develop strategies to cope with EMEs, thereby hopefully reducing the stress of EME-related NDE aftereffects.

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