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Detecção de fugas em tubulações atraves do metodo de resposta em frequencia e reflexões de pulsos de alta frequencia / Leak detection pipes by frequency response method and reflections high frequency pulsesPalhares, Juliana Barbosa 25 August 2005 (has links)
Orientador: Edevar Luvizotto Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-05T20:04:30Z (GMT). No. of bitstreams: 1
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Previous issue date: 2005 / Resumo: Nos sistemas de transporte de fluido líquido, têm-se a preocupação em combater às fugas ou vazamentos. Dessa fonna, este trabalho tem como objetivo aperfeiçoar o método de detecção de fugas em tubulações pelo método de resposta nos domínios fteqüência e tempo, utilizando como ferramentas matemáticas o Método da Matriz Transferência / Resposta em Freqüência e o Método das Características / Transfonnada Rápida de Fourier, sendo demonstradas as vantagens e desvantagens de cada método. E, como contribuição original, propõe um método de detecção de fugas através da análise de pulso de Alta Freqüência, localizando as fugas através da detenninação do tempo que um pulso emitido pela válvula leva para percorrer toda a tubulação e retomar à esta, denominado como Pulso Refletido / Abstract: In liquid fluid transport systems, there is a concem about avoiding leaks. Thus, this work has as objective to improve the leak detection method in pipes by úequency and time domains response method, being used as mathematical tools the method ofTransfer-Matrix / by úequency response and the Method of Characteristics / the Fast Fourier Transform, being demonstrated the advantages and disadvantages of each method. And, as new contribution, propose a leak detection method through the analysis of high frequency pulse, detecting the leaks through determination of time that a pulse produced by the valve takes to go through all pipe and come back, is denominated as a reflected pulse / Mestrado / Recursos Hidricos / Mestre em Engenharia Civil
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Cálculo de harmônicos e inter-harmônicos baseado na norma IEC 61000-4-7Monteiro, Henrique Luis Moreira 17 February 2014 (has links)
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Previous issue date: 2014-02-17 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O cálculo de componentes harmônicos e inter-harmônicos é efetuado geralmente através
do cálculo da FFT (Fast Fourier Transform). Porém, com a utilização desta ferramenta,
alguns problemas podem ser ocasionados de modo que a energia do sinal original se
espalhe ao longo do espectro de frequência. Isto proporciona o surgimento de
componentes que na realidade não existem. Este fenômeno é definido como
espalhamento espectral e acontece pelo fato de haver algum componente interharmônico
fora da resolução da frequência da FFT ou pelo fato do sinal ser amostrado
de forma assíncrona. Para o primeiro caso, utiliza-se a norma IEC 61000-4-7 que
apresenta uma abordagem de grupos e subgrupos a fim de englobar a energia dos interharmônicos
espalhada ao longo do espectro de frequência. Quanto ao sinal amostrado
de forma assíncrona, são apresentados métodos de interpolação no domínio da
frequência e no domínio do tempo para corrigir o resultado obtido através da FFT.
Dessa forma, este trabalho faz uma abordagem da norma IEC e de cada método de
interpolação, comparando-os com intuito de se conhecer o melhor método a ser aplicado
para o cálculo dos componentes contidos no sinal, de acordo com a norma
IEC 61000-4-7. / The harmonic and interharmonic components calculation is usually performance by
using the FFT ( Fast Fourier Transform). However, through the use of this tool, some
problems may arise due the fact that the original signal energy can spread over the
frequency spectrum, promoting the appearance of not actually existing components.
This phenomenon is defined as spectral leakage and happens because either there is
some interharmonic component whose frequency does not match the frequency
resolution of the FFT, or because the signal is sampled asynchronously. In the first case,
IEC 61000-4-7 provides the groups and subgroups approaches to include the
interharmonic energy spreads over the frequency spectrum. In the case of asynchronous
sampled rate, interpolation methods are presented both in the frequency domain and in
time domain for correcting the result obtained through the FFT. Thus, this work
addresses IEC approach and presents how the time and frequency interpolation can be
used to improve the IEC criteria. The interpolation methods are compared in order to
find the best method to be applied for the calculation of the components contained in the
signal, in accordance with IEC 61000-4-7.
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Estimativa da retenção de água no solo a partir do uso de equipamentos não convencionais, redes neurais artificiais e funções de pedotransferência / Water retention soil estimate using nonconventional equipment, artificial neural networks and pedotransfer functionsAntonio Angelotti Netto 06 September 2007 (has links)
O desenvolvimento econômico e o aumento da produtividade agrícola intensificaram o uso de produtos químicos nas lavouras. Quando se pretende quantificar o impacto ambiental de tal uso é necessário empregar modelos que descrevam o fluxo de água e solutos na região não saturada do solo. Para esse fim, um dos parâmetros mais eficazes é conhecer a retenção de água no solo. O objetivo deste trabalho foi desenvolver funções de pedotransferência (FPTs) que estimassem a partir de análise em redes neurais artificiais (RNAs) a retenção de água nos solos da microbacia hidrográfica do ribeirão Canchim, município de São Carlos, SP. Os atributos físicos, textura (argila, silte e areia), densidade e resistência à penetração dos solos: LVAd, LVe, LVdf e NVef, manejados com e sem cobertura vegetal e sob mata foram determinados com equipamentos não convencionais na Embrapa Instrumentação Agropecuária em São Carlos, SP. Esses parâmetros foram utilizados como variáveis de entrada nas duas redes neurais artificiais. Foram obtidas, ainda, as curvas de retenção de água no solo por meio da câmara de pressão de Richards e da tomografia computadorizada, além da porosidade total e da condutividade hidráulica não saturada. O analisador granulométrico de solos e o penetrômetro associado a TDR possibilitaram a obtenção de um grande número de dados. Os atributos físicos dos solos apresentaram grande variabilidade em função da constituição granulométrica e manejos adotados. As RNAs foram eficientes no desenvolvimento de FPTs capazes de estimar a retenção de água com base em propriedades básicas de solo obtidas em grande número. / Economic development and increasing agricultural productivity have intensified the use of chemical products in farming. The quantification environmental impact of these products requires the use of models that describe the flow of water and solutes in the unsaturated region of the soil. For this purpose, one of the most effective parameters belong to the water retention curve of the soil. The purpose of this work was to develop pedotransfer functions (PTFs) to estimate the retention of water by soils of the hydrographic microbasin of the Canchim river, in the municipality of São Carlos, state of São Paulo, Brazil, based on artificial neural networks (ANNs). The physical attributes, granulometry (clay, silt and sand), density and resistance to penetration of LVAd, LVe, LVdf and NVef soils, managed with and without vegetal cover and under forest, were determined using nonconventional equipment at Embrapa Instrumentação Agropecuária in São Carlos, SP. These parameters were used as input variables for two artificial neural networks. The soils\' water retention curves were also obtained using a Richards pressure chamber and computed tomography, as well as their total porosity and unsaturated hydraulic conductivity. A soil granulometric analyzer and a penetrometer allied to TDR provided a large number of data. The soils\' physical attributes displayed a wide variability as a function of their granulometric constitution and adopted managements. The ANNs were effective in developing PTFs able to estimate the water retention based on the large number of basic soil properties.
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Aplicação da reflectometria no domínio do tempo (TDR) na estimativa da condutividade elétrica da solução do solo e de concentrações de nitrato, potássio e cloreto em coluna de solo não saturado / Applying Time domain reflectometry (TDR) on estimating electrical conductivity and nitrate, potassium and chloride concentrations under unsaturated soil columns conditionsIsaac de Matos Ponciano 17 January 2012 (has links)
Devido à importância do monitoramento da composição iônica da solução do solo, no que diz respeito ao meio ambiente e ao manejo da fertirrigação, associada às limitações práticas dos métodos tradicionais de sua determinação é crescente a procura por um método confiável que possibilite o monitoramento desta composição em tempo real e em curtos intervalos de tempo. Neste sentido a TDR tem sido uma alternativa viável. O presente trabalho objetivou, pelo uso da TDR, avaliar o desempenho de sete modelos na determinação da CEw; relacioná-los com a concentração dos íons potássio nitrato e cloreto avaliando os modelos em determinar a concentração dos íons; e por fim monitorar e determinar a concentração destes íons na água lixiviada em coluna de solo não saturado. O trabalho foi divido em dois experimentos, no primeiro os modelos foram calibrados em colunas de solo sendo formado por 24 tratamentos composto por 4 faixas de umidade volumétrica e 6 concentrações da solução de KCl. Para cada coluna de solo era realizada uma leitura com a TDR ( e CEa) e a CEw na solução do solo era determinada por condutivímetro de mesa, nesta solução foram determinadas as concentrações de potássio e cloreto. No segundo experimento o mesmo procedimento foi realizado, entretanto, foi aplicado KNO3 e determinados potássio e nitrato. Desta forma, foi possível calibrar os modelos para a estimativa da CEw, e para determinação das concentrações dos íons potássio, nitrato e cloreto. Os modelos foram avaliados pelos coeficientes de determinação (R²) e exatidão (d), pela estimativa do erro padrão (EEP) e, ainda, foram classificados de acordo com o índice c, produto dos dois coeficientes citados. Os resultados mostram que os modelos de Rhoads et al. (1976) e Vogeler et al. (1996) se ajustam melhor para solos com características texturais argilosas sendo classificados como Ótimos métodos para a determinação da CEw, tanto pela aplicação de KCl como pela aplicação de KNO3 via água de irrigação. Na estimativa da CEw no solo arenoso os modelos de Munõz-Carpena et al. (2005), Mualen e Friedman (1991), Vogeler et al. (1996) e Rhoads et al. (1976) apresentam melhores ajustes na determinação da CEw, sendo classificados com Muito bom. Na determinação do potássio pelos modelos avaliados o melhor ajuste se dá pela associação da relação K-CEw do tipo potência aplicada para solos argilosos e linear para solos arenosos, apresentando classificação de: Ótimo e Muito bom, respectivamente. Para o cloreto e o nitrato o melhor ajuste se dá pela relação de CEw-Cl e CEw-NO do tipo linear, apresentando classificação de Muito Bom e Ótimo respectivamente. A TDR é uma técnica confiável no monitoramento da concentração dos íons potássio e cloreto lixiviados no perfil do solo. / There is a growing demand for a reliable method applied to monitoring ionic composition of soil solution in real-time and short time intervals, due the importance to environmental sustainability and fertigation management and limitations of traditional methods for determination. Time domain reflectometry (TDR) is often considered a viable alternative to traditional methods. Consequently, this research looks for using TDR evaluate the performance of seven mathematical models for determining electrical conductivity (CEw) by comparing simulated and measured concentrations of potassium, nitrate and chloride, and to monitor and determine the concentration of these ions in water leached from unsaturated soil columns. The research was carried out under two experiments conditions. In the first experiment the models were calibrated with input data from 24 soil columns consisting of four soils with six different KCl concentrations. For each soil column CEw was determined by both TDR ( and CEa readings) and the CEw of soil solution was determined by direct measurements of potassium and chloride concentrations. In the second experiment the procedure was the same, but with KCl being replaced with KNO3. This was possible to calibrate the models to estimate the CEw, and to determine potassium, nitrate and chloride ions concentrations. The models were ranked using the c-index, the coefficient of determination (R²) and estimated standard error (ESE). The results showed were Rhoads et al. (1976) and Vogel et al. (1996) classified as \"Great\" for the CEw determination associated with the application of both KCl and KNO3 to irrigation water in clay soils. For estimating CEw in sandy soils, the models Muñoz-Carpena et al. (2005), Mualen and Friedman (1991), Vogel et al. (1996) and Rhoads et al. (1976) were classified as \"Very Good.\" The relationship between CEw and potassium concentration was best represented by a power function in clay soils, and a linear function in sandy soils, with index of \"Great\" and \"Very Good\", respectively. For chloride and nitrate, the best fits were obtained by representing the CEw-Cl and CEw-NO3 relationships with linear functions, which were classified as Very Good and Good, respectively. TDR proved to be a reliable technique for monitoring the concentration of potassium and chloride ions leached in soil profiles.
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Frequency and Time Domain Response Analysis of Transformer Winding for Indirect Measurement of Series Capacitance and Construction of Ladder Network ModelsPramanik, Saurav January 2013 (has links) (PDF)
This thesis proposes innovative methods to extract information embedded in the frequency and time domain response of the transformer winding, and utilizes them to suggest solutions to a few tasks that have until now been thought difficult, if not impossible, to resolve. Pursuing this philosophy originated from the basic under- standing that the response of any physical system (behaving largely as a linear time invariant system) has embedded information that characterizes it completely. So, the prerequisite is to evolve ways to extract this information from measured responses. Once that is done, a variety of interesting applications can be envisaged. The two applications considered in this thesis are-
•Investigate indirect measurement of the series capacitance of a transformer winding using the measured frequency or time domain response
•Explore the possibility of increasing the physical resolution of the ladder network used to model a fully interleaved-disk winding
In the former application, since direct measurement of series capacitance is impossible, alternatives based on indirect measurement were also not attempted. Similarly, in the latter application, the upper limit is known to be fixed by the number of distinctly observable peaks in the magnitude frequency response, so the question of increasing this limit was also never explored. Solutions to these tasks are proposed after a systematic analysis of frequency/time domain responses of a winding, initially modeled as a lumped parameter ladder network, to extract correlations that exist between them and winding parameters, and finally examine how these relations can be exploited together with the measured responses. Each of the five chapters is dedicated to describe the solution to one task. In each chapter, analytical formulation is presented first, followed by experimental results. Good agreement with the predicted results demonstrates its practicability.
In final summary, indirect measurement of the series capacitance of a winding and en- hancing physical resolution of a ladder network model to represent a fully interleaved- disk winding was successfully demonstrated and they are the main contributions of this thesis.
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Simulation de la propagation d'ondes SH dans des structures périodiques et de la diffusion multiple d'ondes de volume en milieux aléatoires / Simulation of shear surface wave propagation in periodic structures and of bulk wave scattering in random mediaGolkin, Stanislav 21 December 2012 (has links)
Cette thèse concerne l’étude de la propagation d’ondes acoustiques dans des structures hétérogènes. Le but essentiel de ces travaux est de confronter des résultats d’expériences numériques effectuées dans le domaine physique (espace, temps) à des prédictions analytiques pour la propagation des ondes de surface SH le long d’un demi-espace stratifié périodique produisant des spectres discontinus de dispersion pour les ondes, ainsi que pour la diffusion multiple dans des milieux aléatoires inclusionnaires (fissures, cavités). Le code numérique FDTD développé lors de cette étude a permis, en autres choses, de corroborer quantitativement les fenêtres spectrales théoriques d’existence des ondes de surface dans les demi-espaces périodiques,ainsi que de montrer des zones de validité fréquentielles des approches analytiques de diffusion multiple concernant les propriétés effectives de milieux aléatoires. / The study is concerned with acoustic waves in elastic media with a different nature of in homogeneity consisting in either periodically continuous or piece wise variation of material properties, or in random sets of defects embedded into a homogeneous matrix, with a given statistical distribution. The scope of problems is topical in non-destructive testing and other applications of ultrasound.Theoretical methods describing involved acoustic phenomena (complex dispersion features, coherent wave in random media, ensemble average techniques) often rely on certain a priori assumptions which render numerical verification especially important.The thesis presents results of analytical modelling of the propagation of surface acoustic waves along periodic half-space, for which the dispersion spectrum is rather complex (discontinuous spectrum of propagation for the surface waves). A 2nd order FDTD numerical code has been developed in order to perform numerical experiments in the space and time domains, and to corroborate the analytical predictions in the frequency domain. A good agreement of simulated results with analytical modelling demonstrates applicability and consistency of the numerical tool. Finally, the code has been used for extracting numerically the coherent wave regime (mean wave over ensemble averaging of the positions of scatterers) for the acoustic propagation in different types of populations of randomly distributed scatterers. The results indicate ranges of validity of some multiple scattering analytical techniques.
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Analyse numérique et expérimentale de la propagation acoustique extérieure : effets de sol en présence d'irrégularités de surface et méthodes temporelles / Numerical and experimental analysis of outdoor sound propagation : ground effects in the presence of surface irregularities and time-domain methodsFaure, Olivier 10 December 2014 (has links)
Dans le contexte de l’amélioration des modèles de prévision en acoustique extérieure, ces travaux de thèse se focalisent sur la modélisation des effets des irrégularités de la surface du sol sur la propagation acoustique. Pour ce faire, des méthodes numériques temporelles sont utilisées : d’une part, la méthode FDTD basée sur la résolution des équations de l’acoustique par des schémas aux différences finies, et d’autre part, la méthode des lignes de transmission (TLM). La modélisation des effets de la rugosité de surface est abordée en considérant le formalisme de l’impédance effective. Deux modèles d’impédance effective sont étudiés : le premier caractérise les effets d’une rugosité déterministe constituée de diffuseurs de géométrie constante, le second caractérise les effets moyens d’une rugosité aléatoire définie par un spectre de rugosité. Ce second modèle est validé expérimentalement par une campagne de mesures en salle semi-anéchoïque, audessus de surfaces rugueuses dont la rugosité a été définie très précisément. Les deux modèles d’impédance effective sont également validés par des simulations numériques FDTD et TLM. La possibilité d’implémenter ces conditions d’impédance effective dans les deux codes temporels est ainsi montrée, ce qui permet de modéliser les effets de la rugosité sans avoir à réaliser un maillage précis du profil des hauteurs de la surface du sol. Une campagne de mesures de l’impédance de différents terrains est réalisée afin d’étudier les effets de la variabilité spatiale et saisonnière de l’impédance sur la prévision des niveaux sonores. Les impédances mesurées lors de cette campagne sont également utilisées comme des données d’entrée réalistes pour le code TLM, afin de simuler et d’étudier les effets de la propagation acoustique au-dessus d’un sol hétérogène présentant une impédance spatialement variable. / In the context of prediction models improvement for outdoor sound propagation, this work focuses on the modelling of the effects of ground irregularities on sound propagation. Time-domain numerical methods are used: on one hand, the solving of the governing equations by finite difference schemes (FDTD method), and on the other hand, the transmission line matrix (TLM) method. Effective impedance is considered to model the effects of surface roughness. Two effective impedance models are studied: the first one takes into account the effects of a deterministic roughness formed by scatterers of constant geometry, the second one takes into account the mean effects of a random roughness defined by a roughness spectrum. This second model is validated experimentally by a measurements campaign carried out in a semi-anechoic chamber, above rough surfaces whose roughness profiles were precisely designed. The two effective impedance models are also validated by FDTD and TLM simulations. The possibility to use the effective impedances directly into the numerical methods is then shown, allowing the modelling of roughness effects without meshing the exact height profile of the ground surface. A measurements campaign of the impedance of different grounds is performed in order to assess the effects of space and seasonal variability of the impedance on the sound levels predictions. The results of this campaign are also used as realistic entry data for the TLM code, and the propagation above a heterogeneous ground showing spatially variable impedance is simulated.
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Modélisation et conception de circuits de réception complexes pour la transmission d'énergie sans fil à 2.45 GHz / Modeling and design of Rectenna Circuits for Wireless Power Transmission et 2.45 GHzTakhedmit, Hakim 18 October 2010 (has links)
Les travaux présentés dans ce mémoire s’inscrivent dans la thématique de la transmission d’énergie sans fil, appliquée à l’alimentation à distance de capteurs, de réseaux de capteurs et d’actionneurs à faible consommation. Cette étude porte sur la conception,l’optimisation, la réalisation et la mesure de circuits Rectennas (Rectifying antennas)compacts, à faible coût et à haut rendement de conversion RF-DC.Un outil d’analyse globale, basé sur la méthode des Différences Finies dans le Domaine Temporel (FDTD), a été développé et utilisé pour prédire avec précision la sortie DC des rectennas étudiées. Les résultats numériques obtenus se sont avérés plus précis et plus complets que ceux de simulations à base d’outils commerciaux. La diode Schottky a été rigoureusement modélisée, en tenant compte de ses éléments parasites et de son boîtier SOT23, et introduite dans le calcul itératif FDTD.Trois rectennas innovantes, en technologie micro-ruban, ont été développées,optimisées et caractérisées expérimentalement. Elles fonctionnent à 2.45 GHz et elles ne contiennent ni filtre d’entrée HF ni vias de retour à la masse. Des rendements supérieurs à 80% ont pu être mesurés avec une densité surfacique de puissance de l’ordre de 0.21 mW/cm²(E = 28 V/m). Une tension DC de 3.1 V a été mesurée aux bornes d’une charge optimale de1.05 k_, lorsque le niveau du champ électrique est égal à 34 V/m (0.31 mW/cm²).Des réseaux de rectennas connectées en série et en parallèle ont été développés. Les tensions et les puissances DC ont été doublées et quadruplées à l’aide de deux et de quatre éléments, respectivement. / The work presented in this thesis is included within the theme of wireless power transmission, applied to wireless powering of sensors, sensor nodes and actuators with low consumption. This study deals with the design, optimization, fabrication and experimental characterization of compact, low cost and efficient Rectennas (Rectifying antennas).A global analysis tool, based on the Finite Difference Time Domain method (FDTD),has been developed and used to predict with a good precision the DC output of studied rectennas. The packaged Schottky diode has been rigorously modeled, taking into account the parasitic elements, and included in the iterative FDTD calculation.Three new rectennas, with microstrip technology, have been developed and measured.They operate at 2.45 GHz and they don’t need neither input HF filter nor via hole connections. Efficiencies more than 80 % have been measured when the power density is 0.21mW/cm² (E = 28 V/m). An output DC voltage of about 3.1 V has been measured with anoptimal load of 1.05 k_, when the power density is equal to 0.31mW/cm² (34 V/m).Rectenna arrays, with series and parallel interconnections, have been developed and measured. Output DC voltages and powers have been doubled and quadrupled using two andfour rectenna elements, respectively.
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Analyse de la stabilité d'impulsion à impulsion des amplificateurs de puissance HEMT GaN pour applications radar en bande S / Pulse-to-pulse stability of GaN HEMT power amplifiers for radar applications in S-bandDelprato, Julien 08 September 2016 (has links)
Les systèmes radar nécessitent d’être de plus en plus performants et doivent émettre des impulsions les plus identiques possibles. Un critère permet de quantifier la bonne régularité des impulsions radar au cours du temps : la stabilité pulse à pulse. L’amplificateur de puissance est un élément essentiel du système radar. Dans ce sens, ce travail présente une analyse du critère de stabilité pulse à pulse dans le cas d’un amplificateur HEMT GaN. Les formules mathématiques permettant d’extraire la valeur de la stabilité pulse à pulse des mesures temporelles d’enveloppe sont présentées. La conception et la réalisation d’un amplificateur de puissance RF connectorisé 50 Ω sont décrites. Divers cas de rafales radar ont été étudiés au travers des mesures temporelles d’enveloppe pour en quantifier l’impact sur les valeurs de stabilité pulse à pulse. Un banc de mesure hétérodyne de la stabilité pulse à pulse a été spécialement développé pendant ces travaux de thèse. Finalement, ces résultats de stabilité pulse à pulse ont été utilisés pour optimiser le modèle électrique non linéaire du transistor HEMT GaN afin de prendre en compte lors des simulations temporelles d’enveloppe les effets de la thermique et des pièges. / Radar-oriented applications require stringent performances. Among them, emitting pulse train with uniform envelope characteristics in term of amplitude and phase. The criterion to quantify the self-consistency of radar signals over the pulse train is the pulse to pulse stability. The power amplifier is the most critical element in the RF radar chain because it has a strong impact on the overall pulse to pulse stability performances. In this context, this work is focused on the study of the impact of a HEMT GaN power amplifier on the pulse to pulse stability. Mathematical approach is presented to derive the pulse to pulse stability from time domain envelope measurements. Design and implementation of a 50Ω matched RF power amplifier are presented. Different radar bursts scenario are investigated and their impact on the pulse to pulse stability are quantified through extensive time domain envelope measurements. For that purpose, a dedicated experimental heterodyne time domain envelope test bench has been developed. These pulse to pulse stability measurements are finally used to optimize and fully validate a nonlinear electrical model of a HEMT GaN, allowing to quantify the relative impact of thermal and trapping effects during circuit envelope simulation in radar-oriented applications.
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Méthodes avancées d'évaluation des charges de vent sur les structures de concentrateurs solairesKaabia, Bassem January 2017 (has links)
L’énergie solaire photovoltaïque concentré (CPV) est une solution de remplacement prometteuse aux structures solaires conventionnelles. Ce type de structure modulable doit être optimisé afin d’être compétitif par rapport aux autres types de production d’énergie. Les forces de vent demeurent la première préoccupation dans la conception de la structure porteuse en acier d’un tel système. L’objectif principal de cette recherche est d’assembler des outils numériques et analytiques afin de prédire les caractéristiques de sa réponse dynamique sous charges de vent turbulent. La maîtrise de cette étape est essentielle afin d’étudier d’une façon plus générique des solutions d’optimisation de la structure support par rapport à sa réponse dynamique sous charges de vent. Pour ce faire, la méthodologie principale de cette étude est composée en trois parties : (i) étude expérimentale à grandeur nature de la réponse globale sous les conditions réelles du vent ; (ii) développement des modèles d’analyse numérique dans lesquels les caractéristiques de structures réelles et des
modèles de forces aérodynamiques adéquates sont prises en compte ; (iii) application des outils développés dans une étude paramétrique pour évaluer plusieurs solutions à partir de cas d’étude dans le contexte d’une conception préliminaire.
Cette thèse est présentée sous forme de deux articles qui ont été soumis dans des revues évaluées par des comités de lecture ainsi que d’un article soumis et présenté dans un congrès international qui démontrent les contributions de cette recherche pour améliorer les pratiques de calcul des charges de vent sur des structures de concentration solaire non conventionnelles. Ces articles sont présentés comme suit (a) Étude expérimentale à échelle réelle de la réponse d’un prototype de concentrateur solaire sous charges de vent. Ce premier article a permis la validation de calcul des coefficients de forces aérodynamiques statiques et la révision des hypothèses de l’application du code ASCE 7-10 pour prédire les forces maximales agissant sur la structure dans la direction du vent ; (b) l’analyse temporelle
de la réponse dynamique d’une structure de concentrateur solaire sous charges de
vent. Cette étude a montré que le modèle et la méthode d’analyse développés selon des hypothèses simplifiées permettaient de prédire correctement les caractéristiques statistiques de la réponse dynamique mesurée en cohérence avec la méthode spectrale stochastique ; (c) Étude des effets des configurations structurales et des paramètres de vent sur l’optimisation de structure solaires sous charges de vent. Cette étude paramétrique a mis en évidence l’importance de l’effet des paramètres structuraux et ceux définissant le vent sur l’optimisation de la conception structural pour ce type de structure. Des recommandations pour optimiser l’action dynamique dans une phase de conception préliminaire ont été proposées. Ce projet de recherche a démontré finalement l’importance d’étudier d’une façon juste et pratique la réponse dynamique sous charges de vent qui mène à résoudre des préoccupations d’optimisation liées à différents types de structures d’énergie solaire en adoptant des hypothèses pratiques pour les ingénieurs. / Abstract : Concentrated Solar Photovoltaic (CPV) is a promising alternative to conventional solar
structures. These solar traking structures need to be optimized to be competitive against
other types of energy production. Wind action is the main concern in the design of the
steel support structure of such movable system. The main purpose of this research is to
assemble advanced numerical and analytical tools that allows realistic dynamic study of
structures under wind loading. This help to study accurately optimized alternative in
term of selecting structural and wind site conditions parameters. The methodology of the
present study involves three main steps : (i) experimental full-scale study of the global
response under real life wind conditions ; (ii) numerical modeling that captures the characteristics
of the real structures and include the aerodynamic force models to conduct
time-domain dynamic analyses ; (iii) preliminary design application that include the study
of the effect of stuctural and wind parameters in optimizing the dynamic wind action and
consequently the steel support structure.
The thesis is presented as an ensemble of three articles written for refereed journals and a
conference that showcase the contributions of the present study to thoroughly understand
the wind load effect on these nonconventionnel structures. The articles presented are as
follow (a) full-scale measurement of the response of a CPV tracker structure prototype
under wind load. The results presented in this first article help design engineers to evaluate
the use of the aerodynamic force coefficients for calculating wind load on similar structures
and to apply properly the ASCE7-10 in evaluating the maximum design wind force using
the equivalent static approach ; (b) time-domain analysis of solar concentrator structure
under gust wind. This study showed that the developed time-domain model using simplified
hypothesis could successfully predict the statistical parameters of the measured
dynamic response in coherence with the stochastic spectral approach ; (c) effect of structure
configurations and wind characteristics on the design of solar concentrator support
structure under dynamic wind action. This parametric study highlighted the importance
of selecting structural and wind parameters in order to minimize the dynamic action and
the steel support structure. Recommendations for optimizing dynamic wind action in a
preliminary design phase were proposed. The present research project has shown the need
to study accurately wind response to solve optimization concerns related to different type
of solar system structures. In addition, this study proposes simplified methods that are
useful for practical engineers when there is the need to solve similar problems.
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