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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.
121

Modelagem da carga de poluição difusa em escala de bacia com valores de concentração média por evento a partir de dados de uma rede de monitoramento local / Modeling the diffuse pollution load at basin scale with event mean concentration values based on data from a local monitoring network

Martins, Renata Genova 06 April 2017 (has links)
As águas superficiais vêm sofrendo impactos em diversas cidades e o escoamento superficial tem sido uma das causas primárias de degradação dos recursos hídricos devido à poluição difusa, além das fontes pontuais, como efluentes domésticos e industriais. A Concentração Média do Evento (CME) tem sido muito utilizada para caracterizar a poluição difusa gerada no escoamento superficial durante o evento de precipitação, além de ser empregada como parâmetro de entrada na estimativa de carga de origem difusa por meio de modelos hidrológicos. Este estudo se dedicou especialmente à avaliação de como a CME influencia a estimativa de cargas difusas quando parâmetro de entrada para modelos hidrológicos. Para isso, além de atividades de campo visando à confecção de modelos de previsão da CME com base em dados reais de uma bacia hidrográfica urbana (Mineirinho, São Carlos, SP) em resposta a eventos chuvosos, buscou-se ajustar, à realidade brasileira, um modelo consagrado para estimativa de cargas difusas e aplicado principalmente em países com clima temperado. Os resultados desta pesquisa mostraram que, em geral, os valores de CME observados são de 2 a 12 vezes maiores que os encontrados na literatura internacional. Em comparação com estudos nacionais, observou-se uma variação nos dados encontrados dependendo das características da bacia hidrográfica monitorada. Além disso, ao adequar o modelo hidrológico L-THIA às características locais, verificou-se um aumento na estimativa da carga de origem difusa quando se utilizavam dados locais. Por fim, com base nas análises realizadas neste estudo, foi possível verificar que os valores de CME que melhor representam as características da bacia hidrográfica do Mineirinho são: nitrogênio total Kjeldahl 6,19 mg.L-1, fósforo total 1,00 mg.L-1, sólidos suspensos totais 870 mg.L-1, chumbo 0,78 mg.L-1, cobre 0,09 mg.L-1 e zinco 0,34 mg.L-1. Reforça-se, portanto, a necessidade de estudos locais para análise da poluição difusa para o planejamento de ações de mitigação de poluição difusa no Brasil. / Surface water has been impacted in several cities and surface runoff has been one of the primary causes of degradation of this resource due to nonpoint source pollution besides the point sources, like domestic effluents and industries. The Event Mean Concentration (EMC) has been widely used to characterize the diffuse pollution generated in the surface runoff during the precipitation event, and it is still used as input parameter in hydrological models that seek to estimate diffuse load. This study focused particularly on the evaluation of how the EMC influences the estimation of diffuse loads as input parameter for hydrological models. To that end, in addition to field activities for the preparation of EMC forecast models based on real data from a river basin in response to rainy events, we attempted to adjust to the Brazilian reality a well-established model for estimating diffuse loads and mainly applied in countries with temperate climate. The results of this research showed that, overall, the EMC observed values are from 2 to 12 times higher than those found in the international literature. Compared with national studies, a variation was observed in the data found depending on the characteristics of the monitored watershed. In addition, when adapting the L-THIA hydrological model to local characteristics, there was an increase in the diffuse source load estimate when using local data. Finally, based on the analyzes carried out in this study, it was possible to verify that the EMC values which best represent the characteristics of the Mineirinho river basin are: Total Kjeldahl Nitrogen 6.19 mg.L-1, Total Phosphorous 1.00 mg.L-1, Total Suspended Solids 870 mg.L-1, Lead 0.78 mg.L-1, Copper 0.09 mg.L-1 and Zinc 0.34 mg.L-1. Therefore, it is necessary to carry out local studies to analyze diffuse pollution in order to create a more solid basis for the planning of mitigation actions to control diffuse pollution in Brazil.
122

Modélisation du rayonnement électromagnétique de boîtiers de blindage par sources équivalentes : application aux matériaux composites / Modelling of shielding enclosures electromagnetic radiation by equivalent sources : application to composite materials

Abdelli, Wassim 15 June 2015 (has links)
La modélisation de matériaux composites est un domaine d’étude qui bénéficie d’un intérêt croissant. En effet, la vulgarisation de l’utilisation de tels matériaux nécessite le développement de nouveaux modèles afin de mieux comprendre leur comportement. L’industrie automobile et aéronautique s’efforce d’optimiser le choix des matériaux en fonction des spécificités de chaque application, afin de réduire la masse des équipements et de leur assurer de meilleurs caractéristiques mécaniques et thermiques. Les matériaux composites se sont aussi présentés comme une éventuelle alternative au métal pour le rôle de blindage électromagnétique. Leur généralisation dans cette optique se heurte néanmoins à une relative méconnaissance de leur comportement électromagnétique. A cet effet, il est nécessaire de disposer de méthodologies permettant d'évaluer l'efficacité de blindage de boîtiers en matériaux composites et de cerner les différents mécanismes et paramètres correspondants.Par ailleurs, le déploiement de ces matériaux alternatifs à plus grande échelle est freiné par d'autres contraintes liées essentiellement à la difficulté de l'analyse électromagnétiques 3D complète de systèmes complexes abritant des boîtiers en matériaux composites. En effet, la complexité topologique de certains composants complique considérablement leur insertion dans les outils de simulation électromagnétique existants. De plus, le rapport d'échelle entre les différents niveaux (système, boîtiers composites, cartes, circuits, composants) est trop important ; cette disparité d'échelle complexifie considérablement la discrétisation géométrique de l'ensemble. L'association de ces différentes contraintes conduisent à des difficultés réelles aux quelles les ingénieurs CEM sont confrontés. C'est pourquoi il est nécessaire de développer des modèles performants permettant de faciliter l'analyse 3D du système hôte complet. Ce travail de thèse s'est donc réparti sur deux volets :- dans un premier temps, nous présentons une méthodologie de calcul de l'efficacité de blindage des boîtiers en matériaux composites, afin d'évaluer la potentialité de ces matériaux en termes de blindage électromagnétique et de cerner les principaux facteurs qui y contribuent.- dans un second temps et dans l'objectif de fournir une approche permettant de mettre les systèmes électroniques complexes intégrant des boîtiers de blindage composites en conformité avec les exigences strictes de CEM, nous proposons une méthodologie de modélisation des rayonnements électromagnétiques. Cette modélisation (à base d’algorithmes génétiques) permet de remplacer les dispositifs ou les boîtiers rayonnants (composites notamment) par un ensemble de dipôles élémentaires. Le modèle équivalent, de type "boîte noire", est ainsi représentatif de l’ensemble de la structure en termes de rayonnement électromagnétique en hautes fréquences et est facilement intégrable dans le maillage de structures hôtes. Ce modèle multipolaire fournit des prédictions spatiales et fréquentielles du champ électrique et magnétique permettant entre autres de calculer l'efficacité de blindage du boîtier dans l'espace, donnant ainsi un moyen de quantifier son impact perturbateur sur son environnement. D'autre part, cette approche permet de simplifier l'analyse 3D d'un système complet abritant des boîtiers composites en contrôlant le comportement EM à tous les niveaux : système, boîtiers, cartes, circuits et composants. / The modeling of composite materials is a domain of study which benefits of increasingly interest. Indeed, the popularization of the use of such materials requires the development of new models in order to better understand their behavior. The automotive and aerospace industry strives to optimize material selection based on the specificities of each application in order to reduce the weight of the equipment and to provide better mechanical and thermal characteristics. Composite materials have been also presented as a potential alternative to metals for the role of electromagnetic shielding. Their generalization in this context is nevertheless hampered by a relative lack of knowledge of their electromagnetic behavior. For this purpose, it is necessary to have methodologies to evaluate the shielding effectiveness of composite enclosures and identify the different corresponding mechanisms and parameters.Moreover, the deployment of these alternative materials on a larger scale is hindered by other constraints related mainly to the difficulty of complete 3D analysis of complex systems including composite enclosures. In fact, the topological complexity of certain components greatly complicates their integration into existing electromagnetic simulation tools. Moreover, the scale ratio between the different levels (system, composite enclosures, electronic card, circuit, component) is too large ; This disparity of scale complexifies considerably the geometrical discretization of the entire system. The combination of these different constraints leads to real difficulties to which EMC engineers face. That is why it is necessary to develop efficient models to facilitate the 3D analysis of the complete host system.This work is therefore divided in two sections :- In a first time, we present a methodology to calculate shielding effectiveness of composite enclosures of electronic equipment. The goal is to evaluate the potential of these materials in terms of electromagnetic shielding and to identify the main contributing factors.- In a second time, and in order to ensure compliance of complex electronic systems incorporating composite shielding enclosures with the stringent requirements of EMC, we propose a modeling methodology of electronic devices radiation. This modeling (based on genetic algorithms) allows to replace the radiating devices and enclosures (especially composites) by a set of elementary dipoles. The equivalent model, "black box" type, is thus representative of the entire structure in terms of high frequency electromagnetic radiation and is easily integrable in the mesh of host structures. This multipolar model provides spatial and frequency predictions of the electric and magnetic field, enabling among others to calculate the shielding effectiveness of the radiating enclosure in space, thereby giving a way to quantify its disruptive impact on its environment. Moreover, this approach allow to simplify the 3D analysis of a complete system comprising composite enclosures by controlling the EM behavior at all levels: system, enclosures, cards, circuits and components.
123

"Dis-lui qu'il n'existe pas". La propagation de la transe grisi siknis chez les Miskitos du Nicaragua / "Tell him he doesn't exist". The Propagation of Grisi siknis Hallucinatory Trance among the Miskitos of Nicaragua

Canna, Maddalena 29 September 2017 (has links)
Grisi Siknis est le calque miskito de l’anglais "crazy sickness". Au-dessous de cette étiquette opaque se cachent une série de crises de transe de masse se reproduisant depuis plus de cinquante ans dans la région de la Moskitia, entre le Nicaragua et le Honduras orientaux. La grisi siknis est un raptus de transe involontaire qui atteint de préférence les jeunes femmes miskitos, une ethnie afro-indigène de langue Misumalpa. Au cours de la transe, les attaqués de grisi siknis (lasa praprukra) tombent en proie à un comportement agressif et/ou auto-agressif associé à des hallucinations récurrentes, ce qui est généralement interprété comme l'attaque d'un esprit maléfique. La diffusion de la maladie est perçue par les affectés comme une épidémie contagieuse redoutable aux thérapies controversées. Néanmoins, le comportement des lasa praprukra présente un certain degré de ritualisation. L’objectif primaire de cette étude, qui s'est appuyée sur une année de recherches ethnographiques au Nicaragua, est de décrire la force de propagation de la grisi siknis, en analysant sa dynamique interactionnelle et la constitution de l'imaginaire qui l'impulse. L’imaginaire iconique lié aux hallucinations de la grisi siknis a été étudié en proposant aux attaqués de dessiner leurs contenus hallucinatoires. Cette pratique, en analogie avec certains traitement chamaniques locaux, a été appréhendée comme une forme de thérapie. Le corpus iconographique produit est analysé dans son double statut de représentation et d’imaginaire incarné doté d’agentivité. En deuxième lieu, la thèse décrit les soubassements neurocognitifs de la crise de transe en esquissant un modèle bayésien de l'induction d'hallucinations sans prise de psychotropes dans des sujets sains. Enfin, le statut social des attaqués de grisi siknis est comparé à ceux de spécialistes rituels tels que les chamanes et des guérisseurs. Une place importante est accordée à la nature ontologiquement instable des esprits impliqués et au rôle de la métacognition dans les modifications psycho-physiologiques qui en favorisent l’expérience et la croyance. / Grisi siknis is a Miskito calque of the English expression « crazy sickness ». Behind this secretive label lies a series of mass trance seizures that have been happening for more than fifty years in the Moskitia region, between Eastern Nicaragua and Honduras. Grisi siknis is an involuntary trance attack, mainly affecting young Miskito women, an afro-indigenous population whose language belongs to the Misumalpa family. During the trance, those attacked by grisi siknis (lasa praprukra) show an aggressive/auto-aggressive behaviour associated with repeated hallucinations, which is generally interpreted as the attack of an evil spirit. The spread of the disease is seen by those affected as a dangerous epidemic which therapies are still controversial. Nevertheless, the lasa praprukra behaviour presents a certain degree of ritualization. The main goal of this study, which relies on one year of ethnographic research in Nicaragua, is to describe grisi siknis propagation by analysing its interactional dynamics and the constitution of the imagery impulsing its spread. The iconic imagery of grisi siknis has been studied by proposing to patients to draw their hallucinatory contents. As it shares some analogies with local shamanic treatment, this practice has been apprehended as a form of therapy. The iconographic corpus of grisi siknis drawings is analysed both in representation and in agentive embodied imagery terms. Secondly, this thesis describes the neurocognitive processes behind the seizure by sketching a Bayesian model of the induction of hallucinations in healthy subjects without psychotropic intake.Finally, the social status of lasa praprukra is compared to those of some local ritual specialists as shamans and healers. An important place is accorded to the fluctuating ontology of the spirits mobilized during the trance, as well as to the role held by metacognition in the psycho-physiological modifications encouraging spirits experience and belief.
124

Design of high frequency operating mechatronic systems : tools and methods of characterization of electromagnetic couplings between electromechanic converters and power electronics converters / Conception d’ensembles mécatroniques à haute fréquence de fonctionnement : outils et méthodes de caractérisation des couplages électromagnétiques entre convertisseur électromécanique et électronique de puissance

Ramos Chavez, Jose Ioav 21 November 2016 (has links)
De l’avion plus électrique, en passant par l’hybridation de véhicules automobiles et jusqu’aux implants cardiaques d’assistance circulatoire, la compacité est devenue le graal de l’électrotechnique embarquée moderne. En effet, la densité de puissance des systèmes électromécaniques ne cesse de s’accroitre. Ainsi, pour répondre aux besoins de forte intégration, les convertisseurs en électronique de puissance trouvent un vecteur de développement dans l’augmentation de leur température et des fréquences de fonctionnement mais aussi dans la réduction des temps de commutation des interrupteurs, leur permettant de réduire leurs pertes thermiques et ainsi, de réduire leurs besoins en refroidissement. Les moteurs et générateurs électriques évoluent avec des topologies aussi diverses qu’innovantes pour répondre aux besoins d’intégration, robustesse et sureté de fonctionnement. Particulièrement, les bobinages des moteurs sont les premiers éléments sur le front de bataille. Au sein du bobinage s’effectuent les échanges entre moteur et convertisseur. L’augmentation des contraintes fréquentielles et transitoires sous forme de fronts de courant et tension issus des ensembles d’électronique de puissance constituent des défis en termes de compatibilité électromagnétique (CEM) pour les systèmes embarqués. Le travail présenté ici est le fruit d’une étroite collaboration entre la société NOVATEM et le laboratoire Génie de Production de l’ENIT de Tarbes au travers d’un financement CIFRE, en association avec la plateforme Labceem de l’IUT de Tarbes. Il propose d’apporter des modèles prédictifs permettant de déterminer les conséquences de ces contraintes d’intégration dans les systèmes mécatroniques de puissance dès les premières étapes de leur conception. Les perturbations conduites dont la source HF est au sein des interrupteurs de puissance du convertisseur, sont façonnées par les impédances caractérisant le chemin de couplage dont le moteur fait partie intégrante. Ce travail vise à élaborer des méthodes et outils pour contribuer à l’étude prédictive de la compatibilité électromagnétique (CEM) des ensembles mécatroniques en essayant de couvrir une plage de fréquence allant de 0 à 300 MHz. Dans une première partie, un état de l’art est détaillé afin de délimiter le contexte et les frontières de l’étude. Puis, un deuxième chapitre porte sur la modélisation analytique de bobinages concentrés de moteurs électriques. Les modèles analytiques établis permettent de déterminer les paramètres de réseaux de circuits pour effectuer des simulations dans le domaine temporel et harmonique. Contrairement aux modèles comportementaux de moteurs répandus dans la littérature, les modèles ici synthétisés prennent en compte les paramètres physiques des bobinages. Ils donnent la possibilité à l’utilisateur de paramétrer les architectures de bobinages concentrés en changeant des paramètres tels que la géométrie des bobines, les matériaux d’isolation ou encore la perméabilité des culasses. Un troisième chapitre, détaille l’établissement d’une méthode rationnelle d’extraction numérique de paramètres fonctionnels et parasites des PCB multicouches de puissance. Cette méthode, de par la prise en compte de paramètres physiques, s’inscrit dans une logique générique et prédictive. Finalement, dans le dernier chapitre, les outils et méthodes précédemment établis sont appliqués à l’étude d’un système réel de motorisation de véhicule électrique développé par la société partenaire Novatem. Le caractère physique et prédictif de ces outils vise à permettre l’expérimentation virtuelle sur l’ensemble moteur-convertisseur sans la nécessité de prototypes. Ce dernier chapitre illustre l’intérêt d’une approche physique en modélisation pour la compatibilité électromagnétique de systèmes mécatroniques. / From the more electrically operated aircraft, to the hybridization of motor vehicles, all the way to electromechanic cardiac implants, compactness has become the holy grail of modern embedded electrical engineering. Indeed, the power-to-weight ratio demands for electromechanical systems has greatly increased. To meet these high integration needs, power electronic converters find a vector of development by increasing their temperature and operating frequencies but also by reducing the switching time of power switches, thus enabling them to reduce their power losses and thereby reducing their cooling requirements. Electric motors and generators operate with various innovative topologies that meet integration, robustness and reliability needs. Motor windings, particularly, are the first motor components on the battle front. It is at the heart of the winding that occur the exchanges between motor and converter. In terms of electromagnetic compatibility (EMC) for embedded systems, the increased frequency and transient stresses in the form of current and voltage edges from the power electronic assemblies are considered steep challenges. The work presented herein is the result of a close cooperation between the company Novatem and the laboratory Génie de Production of ENIT de Tarbes, through CIFRE funding, in combination with the Labceem platform of IUT of Tarbes. Its aim is to develop predictive models that will serve to determine the consequences of such integration constraints in power mechatronic systems that are in the early stages of design. Conducted disturbances whose HF source is located at the inverter power switches are shaped by the impedances characterizing the coupling path of which the electrical machine is an integral part. This work proposes to develop methods and tools to support the predictive study of electromagnetic compatibility (EMC) of mechatronic assemblies, by attempting to cover a modeling frequency range that goes from 0 to 300 MHz’s. In the first chapter of this work, a literature review is detailed for the definition of the context and boundaries of the study. A second chapter focuses on the analytical modeling of concentrated windings in electric motors. The analytical models that are established allow determination of circuit networks settings to perform time- and frequency- domain simulations. Unlike the widespread behavioral models of electrical machine in the literature, the models that are synthesized here take into account the physical parameters of the coils. The user of such models is offered the opportunity to account for the different winding architectures, by changing core parameters such as geometry, insulation materials or permeability. A third chapter describes the establishment of a rational method for extraction of functional and parasitic parameters in multilayer Power PCBs. This method being of a generic and predictive logic aims to account for physical parameters. Finally, in the last chapter, the previously established tools and methods are applied to the study of a real electric vehicle drive system developed by the company Novatem. The physical and predictive value of these tools allows for execution of virtual experimentations on the motorconverter assembly without the need for prototypes. This chapter illustrates the value of a physical approach to modeling the electromagnetic compatibility of mechatronic systems.
125

Méthodologie de prédiction des niveaux d'émission conduite dans les circuits intégrés, à l'aide de VHDL-AMS / A VHDL-AMS based prediction methodology of conducted emission in integrated circuits

Perdriau, Richard 25 March 2004 (has links)
Depuis de nombreuses années, la prise en compte des critères de compatibilité électromagnétique (CEM) constitue une étape capitale dans la conception des systèmes électroniques. Or, l'augmentation de la complexité des circuits intégrés rend indispensable l'étude du comportement électromagnétique directement au niveau du silicium. L'objectif de ces travaux est la définition d'une méthodologie de prédiction, avant fonderie, de l'émission conduite des circuits intégrés. Celle-ci s'appuie sur le langage VHDL-AMS et le modèle ICEM (Integrated Circuit Electromagnetic Model), et peut s'intégrer dans un flot de conception industriel. / For many years, taking into account electromagnetic compatibility (EMC) constraints has been a fundamental requirement in electronic system design. However, the increase in complexity of integrated circuits now demands the study of their electromagnetic behavior at chip level. The objective of this work is the definition of a methodology aimed at predicting conducted emission in integrated circuits. This methodology is based on the VHDL-AMS language and the ICEM (Integrated Circuit Electromagnetic Model) model, and can be integrated into an industrial design flow.
126

Alternative electronic packaging concepts for high frequency electronics

Siebert, Wolfgang Peter January 2005 (has links)
The aim of the research work presented here, is to contribute to the adaptation of electronic packaging towards the needs of high frequency applications. As the field of electronic packaging stretches over several very different professional areas, it takes an interdisciplinary approach to optimize the technology of electronic packaging. Besides this, an extensive knowledge of industrial engineering should be an essential part of this undertaking to improve electronic packaging. Customary advances in technology are driven by new findings and a continuous development of processes in clearly defined fields. However, in the field of the higher levels of the interconnection hierarchy, that is external to the chip level interconnections and chip packaging, it is supposed that a wide combination of disciplines and technical creativity, instead of advanced technology in a special area should produce most added value. The thesis is divided into five areas, interlinked by the overall aim of there advantages to the common goal. These areas are the Printed Wiring Board (PWB) technology, PWB connections using flexible printed circuit boards, multiconductor cable connections, shielded enclosures and the related EMC issues, and finally the cooling of electronics. A central issue was to improve the shielded enclosures to be effective also at very high frequencies; it will be shown that shielded enclosures without apertures can cope with frequencies up to and above 15 GHz. Due to this enclosure without apertures, it was necessary to develop a novel cooling structure. This cooling structure consists of a heat sink where the PCB’s are inserted in close contact to the cooling fins on one side, whereas the other side of the heat sink is cooled by forced ventilation. The heat transfer between these parts is completely inside the same body. Tests carried out on a prototype have shown that the performance of the cooling structure is satisfactory for electronic cooling. Another problem area that is addressed are the interconnect problems in high frequency applications. Interconnections between parts of a local electronic system, or as within the telecom and datacom field between subscribers, are commonly accomplished by cable connections. In this research work multiconductor cables are examined and a patented novel cable-connector for high frequency use is presented. Further, an experimental complex soldering method between flexible printed circuits boards and rigid printed circuits boards, as part of connections between PCBs, is shown. Finally, different sectors of the PCB technology for high frequency applications are scrutinized and measurements on microstrip structures are presented. / QC 20101006
127

Thin Internal Planar Antennas for Mobile Communication Devices

Lin, Yuan-chih 16 December 2006 (has links)
In this dissertation, thin internal antennas for mobile communication devices with a total thickness of less than 10 mm are proposed. There are mainly two differences in the antenna¡¦s construction between the proposed thin internal antennas and conventional planar inverted-F antenna. The first proposed antenna for thin internal antenna is a combo type formed by combining the conventional inverted-F antenna with the monopole antenna. The second proposed antenna is obtained by integrating two radiating arms into a radiating patch. By adjusting the tapering angle and the direction of the end portions, thin internal planar antenna with a thickness of less than 4 mm can be successfully achieved. In these two antennas, their Q-value can be lowered, and then the impedance bandwidth can be effectively improved. This kind of thin internal antennas not only has good impedance matching but also shows good radiation performance. Additionally, by adding a vertical metal wall acting as a RF shielding wall, EM fringing fields between the thin internal EMC antenna and nearby metal components can be effectively supressed. This kind of EMC antennas can effectively eliminate the isolation distance between the antenna and nearby conducting elements to increase the available space on the printed circuit board for additional functions. Besides, multi-band operation is another important function in current mobile devices. In this dissertation, we also studied the effects of the plastic casing and the user¡¦s hand and head on the antenna charateristics. For studying the antenna with the presence of the user¡¦s hand and head, the simulation model provided by SPEAG simulation software SEMCAD is used. From the results obtained, it is seen that the frequency detuning is greatly dependent on the presence of the user¡¦s hand and head. Owing to the presence of the user¡¦s hand and head, large decrease in the radiation efficiency is seen. It also indicates that the radiation efficiency decrease and radiation pattern distortion are mainly owing to the radiation power absorption by the user¡¦s hand and head.
128

Numerische Berechnung elektromagnetischer Felder - Erweiterung einer Hybridmethode aus Momentenmethode und Einheitlicher Geometrischer Beugungstheorie um die Verallgemeinerte Multipoltechnik

Balling, Stefan 30 October 2007 (has links) (PDF)
Drei numerische Feldberechnungsverfahren - die Momentenmehtode, die Einheitliche Geometrische Beugungstheorie und die Verallgemeinerte Multipoltechnik - werden schrittweise zu einer Erweiterten Hybridmethode (EHM) kombiniert. Dabei wird jeder einzelne Kombinationsschritt anschaulich anhand von Beispielen erläutert, die den Vorteil der EHM verdeutlichen: Mit diesem Verfahren lassen sich bestimmte Anordnungen äußerst effektiv analysieren.
129

Assessment and Development of Advanced Power Saving and Supply Concepts For Small Automotive Electronics

TARHAN, Muhammed Mustafa January 2013 (has links)
With rising fuel prices, increasing electrification, and imminent fines on CO2 emission within the EU, the requirement for energy and cost efficient supply concepts is becomingmore and more important in the automotive industry. This thesis presents an assessmentof, and improvement for energy and cost efficient power supply concepts for low-end automotiveand light e-mobility electronic control units, containing small µCs, and analogand logic components. Specifically, linear regulators, synchronous and non-synchronous buck converters, andswitched capacitor converters are investigated and assessed theoretically. The mostpromising concept, namely a discrete buck converter, is further studied using theoreticalassessment, experiment, and simulations. The key result of this work is a concept for replacing commonly used linear regulatorsin small electronic control units (ECUs) by a more efficient supply with only a smallcost adder. Specifically, since no low-end switched converter ICs are available today, wedeveloped a buck converter with discrete control circuit. This concept provides a cheap,yet efficient alternative to linear regulators for a wide range of applications. In addition,the application of this concept is supported by component selection criteria, and also bythe developed simulation models.
130

Μελέτη θαλάμου ηλεκτρομαγνητικής συμβατότητας

Θεοδωρακόπουλος, Ευστάθιος 11 January 2011 (has links)
Ο σκοπός αυτής της εργασίας είναι να προωθηθεί ένας οδηγός σχετικά με τις κατασκευαστικές προδιαγραφές και την απόδοση των ηλεκτρομαγνητικών ανηχοικών θαλάμων και των εσωτερικών εγκαταστάσεων δοκιμής. Εντούτοις, απαιτείται κάποια γνώση ηλεκτρομαγνητικών μετρήσεων, για να εξασφαλιστεί ότι όλοι οι εφαρμόσιμοι κατασκευαστικοί παράγοντες, έχουν εφαρμοστεί στις καταστάσεις που θα ζητηθούν. Η μέτρηση των ηλεκτρομαγνητικών κυμάτων περιλαμβάνει μεγάλο αριθμό ηλεκτρονικών συσκευών. Αυτές οι συσκευές μπορούν να ταξινομηθούν σε άμεσους ή σε έμμεσους εκπομπούς. Η μέτρηση των άμεσων εκπομπών (όπως οι κεραίες) ή η εκπομπή της ηλεκτρομαγνητικής ενέργειας, όπως στη διατομή του ραντάρ, απαιτεί εξειδικευμένες εγκαταστάσεις. Ο καθορισμός του επιπέδου ακτινοβολίας από τους έμμεσους εκπομπούς όπως οι ψηφιακές συσκευές ή ο καθορισμός του επιπέδου «ευαισθησίας» που έχει μια ηλεκτρονική συσκευή, όσον αφορά ένα εισερχόμενο ηλεκτρομαγνητικό κύμα περιλαμβάνει επίσης τη μέτρηση των ηλεκτρομαγνητικών κυμάτων στις εγκαταστάσεις που σχεδιάζονται συγκεκριμένα για τη μέτρηση που πραγματοποιείται. Ηλεκτρομαγνητικό κύμα είναι το αποτέλεσμα από την επιτάχυνση των ηλεκτρικών φορτίων. Το ηλεκτρικό πεδίο λόγω μιας ανεπιθύμητης φόρτισης (σε κάποια δοκιμή ή στην ομοιόμορφη κίνηση σε μια ευθεία γραμμή) κατευθύνεται ακτινωτά και μειώνεται ως το τετράγωνο της απόστασης από τη φόρτιση. Εντούτοις, η επιτάχυνση της φόρτισης προκαλεί αύξηση του ηλεκτρικού πεδίου, και μειώνεται γραμμικά με την απόσταση. Στην πράξη, σχεδόν πάντα υπάρχει ενδιαφέρον για τα μακροσκοπικά αποτελέσματα. Στην μακροσκοπική κλίμακα, η αλληλεξάρτηση μεταξύ των ηλεκτρικών και μαγνητικών πεδίων περιγράφεται από μαθηματική άποψη από τις εξισώσεις Maxwell [ 2 ..3 ]. Τα μαθηματικά των ηλεκτρομαγνητικών πεδίων και των σχετικών μέσων χρησιμοποιούν την διανυσματική ανάλυση. Η ανάλυση μπορεί να αναμιχθεί πολύ, σε πολλά προβλήματα, ειδικά εκείνα που περιλαμβάνουν τη διάδοση στα μη ισοτροπικά , μη-αμοιβαία, μη γραμμικά, ή ανομοιογενή μέσα. Αν και ορισμένα προβλήματα στις ηλεκτρομαγνητικές μετρήσεις μπορούν να απαιτήσουν την εφαρμογή πιο λεπτομερών μαθηματικών. Στους ανηχοικούς θαλάμους πραγματοποιούνται δύο ειδών δοκιμές, η δοκιμή ηλεκτρομαγνητικής παρεμβολής (EMI) και η δοκιμή ηλεκτρομαγνητικής συμβατότητας (EMC). Ηλεκτρομαγνητική παρεμβολή (EMI) είναι κάθε σήμα ή εκπομπή που ακτινοβολείται στον χώρο ή άγεται σε καλώδια τροφοδοσίας ή σημάτων και θέτει σε κίνδυνο τη λειτουργία συστημάτων ασύρματης πλοήγησης ή άλλες υπηρεσίες ασφαλείας ή υποβαθμίζει, παρεμποδίζει ή διακόπτει επανειλημμένα μια αδειοδοτημένη υπηρεσία ασύρματων επικοινωνιών. Στις υπηρεσίες ασυρμάτων επικοινωνιών περιλαμβάνονται, ενδεικτικά, οι εμπορικές εκπομπές AM/FM, η τηλεόραση, η κινητή τηλεφωνία, τα ραντάρ, ο έλεγχος εναέριας κυκλοφορίας, η τηλεειδοποίηση και οι Υπηρεσίες Προσωπικής Επικοινωνίας (Personal Communication Services ή PCS). Αυτές οι αδειοδοτημένες και οι μη αδειδοτημένες υπηρεσίες ασυρμάτων επικοινωνιών, όπως το WLAN ή το Bluetooth, μαζί με ακούσιους πομπούς όπως ψηφιακές συσκευές, συμπεριλαμβανομένων συστημάτων υπολογιστών, συμβάλλουν στο ηλεκτρομαγνητικό περιβάλλον. Η ηλεκτρομαγνητική συμβατότητα (ΗΜΣ) είναι η δυνατότητα στοιχείων του ηλεκτρονικού εξοπλισμού να λειτουργούν ομαλά μαζί, μέσα σε ηλεκτρονικό περιβάλλον. Παρόλο που το συγκεκριμένο σύστημα υπολογιστή έχει σχεδιαστεί και έχει προσδιοριστεί ως συμβατό με τα όρια που καθορίζονται από το φορέα κανονισμών για ηλεκτρομαγνητικές παρεμβολές, δεν παρέχεται κανενός είδους εγγύηση ότι δεν θα υπάρξει παρεμβολή σε μία συγκεκριμένη εγκατάσταση. Τα προϊόντα της EMC Corporation είναι σχεδιασμένα, ελεγμένα και κατηγοριοποιημένα σύμφωνα με το συγκεκριμένο ηλεκτρομαγνητικό περιβάλλον χρήσης τους. Αυτές οι κατηγορίες ηλεκτρομαγνητικού περιβάλλοντος αναφέρονται γενικά στους ακόλουθους εναρμονισμένους ορισμούς: • Τα προϊόντα κατηγορίας B προορίζονται για χρήση σε οικιακά περιβάλλοντα, αλλά μπορούν επίσης να χρησιμοποιηθούν σε μη οικιακά περιβάλλοντα. Σημείωση: Οικιακό περιβάλλον είναι ένα περιβάλλον όπου η χρήση πομπών ραδιοσυχνοτήτων και τηλεοπτικών δεκτών μπορεί να είναι αναμενόμενη σε απόσταση 10 m από το σημείο που χρησιμοποιείται το προϊόν. • Τα προϊόντα κατηγορίας A προορίζονται για χρήση σε μη οικιακά περιβάλλοντα. Τα προϊόντα κατηγορίας A μπορούν επίσης να χρησιμοποιηθούν σε οικιακά περιβάλλοντα, αλλά ενδέχεται να προκαλέσουν παρεμβολές και να απαιτηθεί η λήψη διορθωτικών μέτρων από το χρήστη. Εάν αυτός ο εξοπλισμός προκαλέσει παρεμβολή σε υπηρεσίες ραδιοεπικοινωνιών, η οποία παρεμβολή διαπιστώνεται ενεργοποιώντας και απενεργοποιώντας τον εξοπλισμό, επιχειρήστε να διορθώσετε την παρεμβολή ενεργώντας ως εξής: • Επαναπροσανατολισμός της κεραίας λήψης. • Αλλαγή θέσης του υπολογιστή σε σχέση με το δέκτη. • Μετακίνηση του υπολογιστή μακριά από το δέκτη. • Σύνδεση του υπολογιστή σε διαφορετική πρίζα έτσι ώστε ο υπολογιστής και ο δέκτης να βρίσκονται σε διαφορετικά κυκλώματα. Εάν είναι απαραίτητο, επικοινωνήστε με έναν τεχνικό υποστήριξης της EMC Corporation ή κάποιο εξειδικευμένο τεχνικό ραδιοφώνων/τηλεοράσεων ή ειδικό ΗΜΣ για περαιτέρω υποδείξεις. Ο εξοπλισμός τεχνολογίας πληροφοριών (ITE) που περιλαμβάνει περιφερειακά όπως κάρτες επέκτασης, εκτυπωτές, συσκευές εισόδου/εξόδου (I/O), οθόνες κ.λπ., και οι οποίες είναι ενσωματωμένες μέσα στο σύστημα ή συνδεδεμένες σε αυτόν, πρέπει να συμμορφώνεται με την κατηγορία ηλεκτρομαγνητικού περιβάλλοντος του υπολογιστή. / The purpose of this paper is to provide a guide on the design and performance specification of electromagnetic anechoic chambers or indoor test facilities. However, some knowledge of electromagnetic measurements is required to ensure that all applicable design factors have been applied in any given design situation. The measurement of electromagnetic waves involves a large number of electronic devices. These devices can be categorized as intentional or unintentional radiators. Measurement of intentional radiators (such as antennas) or the scattering facilities. Determining the level of radiation from unintentional radiators such as digital devices or determining the level of immunity an electronic device has with respect to an impinging electromagnetic wave also involves the measurement of electromagnetic waves in testing facilities designed specifically for the measurement to be performed. Electromagnetic waves result from the acceleration of electric charges. The electric field due to an unaccelerated charge (one at rest or in uniform motion in a straight line) is radially directed and decreases as the square of the distance from the charge. However, the acceleration of the charge gives rise to a tangential component of the electric field, and this decreases linearly with distance. This time-varying electric field has associated with it a time varying magnetic field, together, they comprise an electromagnetic field. An electromagnetic field that decreases linearly with distance represents an outward radiation. In practice, one is almost always concerned with macroscopic effects resulting from acceleration of gross numbers of charges. On the macroscopic scale, the interrelationship between electric and magnetic fields is described mathematically by Maxwell’s equations. An additional set of equations called constitutive relationships specifies the characteristics of the medium in which the field exists. The mathematics of electromagnetic fields and the associated media makes use of vector and tensor analysis. The analysis can become very involved in many problems, especially those involving propagation in nonisotropic, nonreciprocal, nonlinear, or nonhomogeneous media. Although certain problems in electromagnetic measurements can require application of more detailed mathematics. In anechoic chambers, take place two types of tests, the electromagnetic interference test (EMI) and the electromagnetic compatibility testing (EMC). Electromagnetic interference (EMI) is any signal or emission radiated in space or is induced in cables or signals and threatening the operation of wireless navigation services or other security or degrade, obstruct or repeatedly interrupts a licensed radio communications service. In wireless communications services including, without limitation, commercial broadcasting AM / FM, TV, mobile telephony, radar, air traffic control, paging and personal communications services (Personal Communication Services or PCS). These licensed and non licensed wireless communications such as WLAN or Bluetooth, along with unintentional transmitters such as digital devices, including computer systems, contribute to the electromagnetic environment. The electromagnetic compatibility (EMC) is the potential components of electronic equipment to operate seamlessly together in an electronic environment. While this computer system has been designed and determined to be compatible with the limits set by the service regulations for electromagnetic interference, there is no guarantee that interference will not occur in a particular installation. Its products are EMC Corporation is designed, tested and categorized according to the specific electromagnetic environment of use. These types of electromagnetic environment generally refers to the following harmonized definitions: • Products category B for use in domestic environments, but can also be used in non-domestic environments. Note: the domestic environment is an environment where the use of RF transmitters and television receivers may be expected within 10 m from where the product is used. • Class A products are intended for use in non-domestic environments. Class A products can also be used in domestic environments, but it may cause interference and require remedial action by the user. If this equipment cause interference to radio services, which insert shows activating and disabling the equipment, try to correct the interference by acting as follows: • Reorient the receiving antenna. • Relocating the computer to the receiver. • Move the computer away from the receiver. • Connect the computer into a different outlet so that computer and receiver are on different circuits. If necessary, contact technical support EMC Corporation or any qualified radio / TV technician or special EMC for further instructions. Information technology equipment (ITE), including peripherals such as expansion cards, printers, input / output (I / O), monitors, etc., which are embedded in the system or connected to it, must comply with Category electromagnetic environment of the computer.

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