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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.
1

Time-domain distortion analysis of wideband electromagnetic field sensors using orthogonal polynomial subspaces

Saboktakinrizi, Shekoofeh 07 April 2011 (has links)
In this thesis, a method of distortion analysis of electromagnetic field sensors using orthogonal polynomial subspaces is presented. The effective height of the sensor is viewed as the impulse response of a linear system. The impulse response corresponds to a linear transformation which maps every electromagnetic incident field waveform to a received voltage waveform. Hermite and Laguerre orthogonal polynomials are used as the basis sets for the subspace of incident electromagnetic field waveforms. Using the selected basis set, a transformation matrix is calculated for the sensors. The transformation matrices are compared to a reference transformation matrix as a measure of distortion. The transformation matrices can describe the sensor behavior up to a certain frequency range. The limits on this frequency range are investigated for both Hermite-Gauss and Laguerre functions. The unique property of Laguerre functions is used to prove that the transformation matrix has a particular pattern. This method is applied on case studied sensors both in computer simulation and measurements.
2

Time-domain distortion analysis of wideband electromagnetic field sensors using orthogonal polynomial subspaces

Saboktakinrizi, Shekoofeh 07 April 2011 (has links)
In this thesis, a method of distortion analysis of electromagnetic field sensors using orthogonal polynomial subspaces is presented. The effective height of the sensor is viewed as the impulse response of a linear system. The impulse response corresponds to a linear transformation which maps every electromagnetic incident field waveform to a received voltage waveform. Hermite and Laguerre orthogonal polynomials are used as the basis sets for the subspace of incident electromagnetic field waveforms. Using the selected basis set, a transformation matrix is calculated for the sensors. The transformation matrices are compared to a reference transformation matrix as a measure of distortion. The transformation matrices can describe the sensor behavior up to a certain frequency range. The limits on this frequency range are investigated for both Hermite-Gauss and Laguerre functions. The unique property of Laguerre functions is used to prove that the transformation matrix has a particular pattern. This method is applied on case studied sensors both in computer simulation and measurements.
3

Influence de la recharge rapide sur les performances des accumulateurs lithium des véhicules électriques dans le cadre de l'utilisation postale / Influence of fast charging on the performances of lithium batteries for electric vehicles used in mail delivery missions.

Al jed, Habib 15 December 2014 (has links)
Cette thèse a pour objectif d’étudier l’influence de la recharge rapide sur le vieillissement des batteries lithium, et son impact sur les performances des véhicules électriques dans le cadre d’une utilisation postale. La première partie est consacrée à la modélisation de batteries lithium par un modèle à circuit électriques équivalent, dont les paramètres sont identifiables par des tests de caractérisation linéaires. La deuxième partie est dédiée à l’étude du vieillissement, et abouti sur un estimateur de vieillissement par l’exploitation des données des tests de vieillissement accélérés. Ensuite, l’utilisation postale est étudiée, et un profil de courant représentatif de la sollicitation réelle de la batterie est proposé. Ce dernier a permis de valider le modèle de la batterie dans le domaine de l’utilisation postale. Ensuite un modèle de véhicules électriques est présenté, il intègre le modèle de batterie, tout en le faisant vieillir en utilisant l’estimateur de vieillissement. Enfin, les différentes stratégies de recharges possibles sont énumérées et comparées. Pour conclure sur leurs influences sur le vieillissement des batteries, et donc les performances de véhicules. / This thesis aims to study the influence of fast charging on the aging of lithium batteries, and its impact on the performances of electric vehicles as part of a postal use. The first part is devoted to the modeling of lithium batteries with an equivalent electric circuit model, whose parameters could be identified using linear characterization tests. The second part is dedicated to the study of aging, and results in an aging estimator using data collected from accelerated aging tests programs. Then the postal usage is studied, and a power profile representative of the actual load on the battery is provided. The latter was used to validate the model of the battery in the field of postal use. Then the postal use is studied, and a current profile representative of the real behavior of the battery is provided. This profile was used to validate the model of the battery in the postal use domain. Then a model of electric vehicles is presented, it integrates the battery model, which can simulates the aging state of the battery using the ageing estimator. Finally, the various possible strategies of recharge are listed and compared, which leads to conclusions about their influences on aging of batteries, and the vehicles performance.
4

Etude et mise en œuvre d’un banc intégré et étalonné 4 canaux pour la caractérisation temporelle de dispositifs non-linéaires hyperfréquences / Study and implementation of a 4-channel integrated and calibrated time-domain characterization system for the characterization of non-linear microwave devices

Farah, Saïd 10 March 2017 (has links)
Ce travail de cette thèse propose une conception et une réalisation d’un banc intégré de caractérisation temporelle des dispositifs RF non-linéaires conçu avec des récepteurs de type THA. Ce banc est une version miniaturisée, moins onéreuse et à performances comparables d’un banc similaire « éclaté » et développé au sein d’XLIM. Le banc intégré développé dans ce travail est entièrement étalonné. Il est versatile vis-à-vis des techniques de sous échantillonnage mis en œuvre pour mesurer des signaux RF sur des temps d’acquisition très différents (<50 µs ou < quelques ms). La technique CIS est utilisée pour l’acquisition périodiques de signaux RF périodiques de durée courtes. La technique DQD est utilisée pour l’acquisition périodiques ou apériodique de signaux RF périodiques ou apériodiques. Cet outil a été utilisé pour extraire, à partir des formes d’ondes temporelles mesurées à leurs accès, plusieurs paramètres caractéristiques (AM/AM- AM/PM, EVM) d’amplificateurs GaN de gamme 10 à 50 W soumis à des excitations simples ou à des signaux modulés. Ce manuscrit décrit aussi la mise en œuvre le développement, parallèlement au travail précédent, d’une plateforme de laboratoire de travaux pratiques à distance pour le projet européen TEMPUS EOLES. / This work proposes the design and the realization of a 4-channel integrated and calibrated time-domain characterization system for the characterization of non-linear microwave devices. This integrated measurement system uses THA based receivers. This is a miniaturized, less expensive and comparable version of a similar laboratory available tool developed within XLIM. The integrated instrument developed in this work is fully calibrated. It is versatile with respect to sub-sampling techniques used to measure RF signals over very different acquisition times (<50 µs or < few ms). The CIS technique is used for the periodic acquisition of periodic short duration RF signals. The DQD technique is used for the periodic or aperiodic acquisition of periodic or aperiodic RF signals. This tool was used to extract, from the measured time-domain waveforms at their ports, several characteristic parameters (AM/AM-AM/PM, EVM) of GaN amplifiers operating in the 10 to 50 W range and excited with simple or modulated signals. This manuscript also describes the implementation, and the development, performed along with the previous work, of a laboratory platform for remote practical works in the context of the European project TEMPUS EOLES.

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