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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.
11

Measurements and multifractal analysis of turbulent temperature and velocity near the ground

Wang, Yu, 1964- January 1995 (has links)
No description available.
12

Estudo e implementação de dispositivo de calibração de velocímetro automotivo. / Study and implementation of a calibration device for a speedometer.

Celestino, Marcelo 02 March 2007 (has links)
O presente trabalho reúne elementos para a análise dos principais problemas e dificuldades inerentes à implementação de um dispositivo para a aferição de velocímetros de veículos automotores, de forma a atender a legislação prevista no código nacional de Trânsito, determinada pela Portaria n.º 115 de 1998, que define erros máximos permitidos para velocímetros de ± 5km/h para velocidades de até 100km/h e de ± 5% para velocidades acima de 100km/h. Inicialmente são apresentados e comparados os principais métodos de medição de velocidade abordados na literatura. A partir desta análise, é implementado um método inovador decorrente do efeito de escorrimento ou blur, onde, através do estudo das características e regularidades contidas em uma única imagem borrada, será determinada a velocidade da superfície em análise. A partir de uma bancada que simula o solo em movimento e, utilizando-se uma câmera CCD (Charge Coupled Device) e um frame grabber, fez-se a aquisição de imagens da superfície asfáltica em movimento. A informação de velocidade pôde então ser determinada, através da análise das regularidades contidas na imagem dinâmica devido ao efeito de escorrimento ou efeito blur. Obteve-se resultados suficientes para a aferição de velocímetros, com erros máximos abaixo de 5%. A técnica desenvolvida e avaliada na prática através de uma bancada que simula o asfalto em movimento, demonstrou uma precisão de 0,8% numa faixa de velocidades de 0 a 20km/h , de 1,5% numa faixa de velocidades de 20 a 60km/h e de 2,5% numa faixa de velocidades de 60km/h a 80km/h. Finalmente foram investigados os fatores preponderantes que limitaram os erros nesta ordem de grandeza. / This work gathers elements for the study and analysis of the main problems and difficulties inherents to the implementation of a device to the gauging of a speedometer of automotive vehicles, in order to meet the foreseen legislation described by the governmental decree nº 115 from 1998, which defines the maximum allowed error for speedometers of ± 5km/h for speeds till 100km/h and ± 5% for speeds above 100km/h. From this study, a new method, based on the blur effect, is proposed. In the method, the speed of the target surface is determined by analyzing the characteristics and regularities contained in a single blurred image. Starting from a device that simulates the soil movement and, using a CCD (Charge Coupled Device) camera and a frame grabber, the acquisition of images of the moving asphalt surface was done. The information of speed then could be determined, through the study of the regularities contained in the dynamic image due to the blur effect. The necessary results for the gauging have been achieved with success, with precision below 5%. The developed and evaluated technique in practice through a device that simulates the asphalt in movement has demonstrated a precision of 0,8% in a range of speeds from 0 to 20km/h, 1,5% in a range of speeds from 20km/h to 60km/h and 2,5% in a range of speeds from 60km/h to 80km/h. Finally, it was investigated the preponderant factors which have limited the errors in this order of greatness.
13

Estimação de velocidade de composições usando processamento de vídeo / Speed estimation.of trains using vídeo processing

Evelyn da Silva Viana 05 August 2011 (has links)
Esta dissertação tem como objetivo estudar um método para estimar a velocidade de veículos ferroviários usando processamento de vídeo. O sistema proposto consiste na utilização de câmeras ao longo das vias férreas que permitam não só o monitoramento do tráfego ferroviário, mas cujo vídeo captado possa ser utilizado para a obtenção de estimativas para a velocidade instantânea dos trens que por ela trafegam. Tal sistema seria utilizado independentemente dos sistemas de controle já utilizados pela operadora do sistema ferroviário, permitindo que os controladores possam ter uma segunda análise no caso de falha da primeira, assim como um modelo que permita avaliar a velocidade instantânea do veículo ferroviário ao longo do percurso. Os algoritmos de rastreamento empregados para esse fim abordaram diferentes métodos. Confrontaram-se os resultados obtidos com os algoritmos propostos com os dados empíricos de forma a determinar aquele com melhor resposta dada as características do sistema. O algoritmo que apresentou os melhores resultados emprega um único bloco de referência para todos os quadros comparados. A métrica de similaridade responsável por determinar quais blocos são mais ou menos similares dentro do universo de busca estipulado é a soma de diferenças absolutas (SAD, Sum of Absolute Differences). O tempo de processamento requerido por cada um dos métodos de rastreamento estudados também foi considerado nas avaliações de resultados apresentadas. Uma comparação realizada entre as velocidades coletadas e aquelas informadas pelo sistema de controle mostraram que os resultados obtidos com o sistema atual, utilizando a sinalização apenas por circuito de via apresenta resultados pouco confiáveis com erros bastante significativos. Os resultados obtidos com o sistema proposto apresentaram erros menores quando comparados àqueles obtidos pelo sistema vigente, apresentando-se assim como uma solução viável e de baixo custo quando comparada às técnicas atualmente empregadas para a medida de velocidade de trens. / This dissertation aims to study a method of estimating the speed of railway vehicles using video processing. The proposed system uses cameras disposed alongside railways to monitor traffic as well as estimate train speeds. Such a system would allow the machinist to have a backup control system, regardless of the control systems already used by the operator of the rail system. In this dissertation, tracking algorithms with different methods are discussed. By comparing results obtained with the proposed algorithm and results from empirical data, it was possible to determine the one that best provided the desired results given the characteristics of the system. The algorithm which presented the best results was the one that employs a single block for all reference frames compared. The metric of similarity used for determining which blocks are most similar within the searched universe is the sum of absolute differences (SAD). The processing time required by each of the screening methods studied was also considered in assessing the results presented. A comparison between the rates collected and those informed by the control system showed that the results obtained with the current system, which only uses the signal track circuit, provides unreliable results with very significant errors. The results obtained with the proposed system had errors smaller than those obtained with the current system, suggesting the proposed system is viable and cost-effective compared to currently employed techniques.
14

Estimação de velocidade de composições usando processamento de vídeo / Speed estimation.of trains using vídeo processing

Evelyn da Silva Viana 05 August 2011 (has links)
Esta dissertação tem como objetivo estudar um método para estimar a velocidade de veículos ferroviários usando processamento de vídeo. O sistema proposto consiste na utilização de câmeras ao longo das vias férreas que permitam não só o monitoramento do tráfego ferroviário, mas cujo vídeo captado possa ser utilizado para a obtenção de estimativas para a velocidade instantânea dos trens que por ela trafegam. Tal sistema seria utilizado independentemente dos sistemas de controle já utilizados pela operadora do sistema ferroviário, permitindo que os controladores possam ter uma segunda análise no caso de falha da primeira, assim como um modelo que permita avaliar a velocidade instantânea do veículo ferroviário ao longo do percurso. Os algoritmos de rastreamento empregados para esse fim abordaram diferentes métodos. Confrontaram-se os resultados obtidos com os algoritmos propostos com os dados empíricos de forma a determinar aquele com melhor resposta dada as características do sistema. O algoritmo que apresentou os melhores resultados emprega um único bloco de referência para todos os quadros comparados. A métrica de similaridade responsável por determinar quais blocos são mais ou menos similares dentro do universo de busca estipulado é a soma de diferenças absolutas (SAD, Sum of Absolute Differences). O tempo de processamento requerido por cada um dos métodos de rastreamento estudados também foi considerado nas avaliações de resultados apresentadas. Uma comparação realizada entre as velocidades coletadas e aquelas informadas pelo sistema de controle mostraram que os resultados obtidos com o sistema atual, utilizando a sinalização apenas por circuito de via apresenta resultados pouco confiáveis com erros bastante significativos. Os resultados obtidos com o sistema proposto apresentaram erros menores quando comparados àqueles obtidos pelo sistema vigente, apresentando-se assim como uma solução viável e de baixo custo quando comparada às técnicas atualmente empregadas para a medida de velocidade de trens. / This dissertation aims to study a method of estimating the speed of railway vehicles using video processing. The proposed system uses cameras disposed alongside railways to monitor traffic as well as estimate train speeds. Such a system would allow the machinist to have a backup control system, regardless of the control systems already used by the operator of the rail system. In this dissertation, tracking algorithms with different methods are discussed. By comparing results obtained with the proposed algorithm and results from empirical data, it was possible to determine the one that best provided the desired results given the characteristics of the system. The algorithm which presented the best results was the one that employs a single block for all reference frames compared. The metric of similarity used for determining which blocks are most similar within the searched universe is the sum of absolute differences (SAD). The processing time required by each of the screening methods studied was also considered in assessing the results presented. A comparison between the rates collected and those informed by the control system showed that the results obtained with the current system, which only uses the signal track circuit, provides unreliable results with very significant errors. The results obtained with the proposed system had errors smaller than those obtained with the current system, suggesting the proposed system is viable and cost-effective compared to currently employed techniques.
15

Estudo e implementação de dispositivo de calibração de velocímetro automotivo. / Study and implementation of a calibration device for a speedometer.

Marcelo Celestino 02 March 2007 (has links)
O presente trabalho reúne elementos para a análise dos principais problemas e dificuldades inerentes à implementação de um dispositivo para a aferição de velocímetros de veículos automotores, de forma a atender a legislação prevista no código nacional de Trânsito, determinada pela Portaria n.º 115 de 1998, que define erros máximos permitidos para velocímetros de ± 5km/h para velocidades de até 100km/h e de ± 5% para velocidades acima de 100km/h. Inicialmente são apresentados e comparados os principais métodos de medição de velocidade abordados na literatura. A partir desta análise, é implementado um método inovador decorrente do efeito de escorrimento ou blur, onde, através do estudo das características e regularidades contidas em uma única imagem borrada, será determinada a velocidade da superfície em análise. A partir de uma bancada que simula o solo em movimento e, utilizando-se uma câmera CCD (Charge Coupled Device) e um frame grabber, fez-se a aquisição de imagens da superfície asfáltica em movimento. A informação de velocidade pôde então ser determinada, através da análise das regularidades contidas na imagem dinâmica devido ao efeito de escorrimento ou efeito blur. Obteve-se resultados suficientes para a aferição de velocímetros, com erros máximos abaixo de 5%. A técnica desenvolvida e avaliada na prática através de uma bancada que simula o asfalto em movimento, demonstrou uma precisão de 0,8% numa faixa de velocidades de 0 a 20km/h , de 1,5% numa faixa de velocidades de 20 a 60km/h e de 2,5% numa faixa de velocidades de 60km/h a 80km/h. Finalmente foram investigados os fatores preponderantes que limitaram os erros nesta ordem de grandeza. / This work gathers elements for the study and analysis of the main problems and difficulties inherents to the implementation of a device to the gauging of a speedometer of automotive vehicles, in order to meet the foreseen legislation described by the governmental decree nº 115 from 1998, which defines the maximum allowed error for speedometers of ± 5km/h for speeds till 100km/h and ± 5% for speeds above 100km/h. From this study, a new method, based on the blur effect, is proposed. In the method, the speed of the target surface is determined by analyzing the characteristics and regularities contained in a single blurred image. Starting from a device that simulates the soil movement and, using a CCD (Charge Coupled Device) camera and a frame grabber, the acquisition of images of the moving asphalt surface was done. The information of speed then could be determined, through the study of the regularities contained in the dynamic image due to the blur effect. The necessary results for the gauging have been achieved with success, with precision below 5%. The developed and evaluated technique in practice through a device that simulates the asphalt in movement has demonstrated a precision of 0,8% in a range of speeds from 0 to 20km/h, 1,5% in a range of speeds from 20km/h to 60km/h and 2,5% in a range of speeds from 60km/h to 80km/h. Finally, it was investigated the preponderant factors which have limited the errors in this order of greatness.
16

Technique et Méthodologie de Conception du Réseau de Distribution d'Alimentation d'une Carte Electronique Rapide à Haute Densité d'Interconnexion / Design Techniques and Methodology for Power Delivery Network of a High Speed High Sensity Electronic Board

Goral, Benoit 12 October 2017 (has links)
Les contraintes économiques actuelles amènent les entreprises d'électronique non seulement à innover à un rythme très soutenu mais aussi à réduire le cycle de conception des nouveaux produits. Afin de rester compétitives, ces entreprises doivent proposer régulièrement de nouveaux produits comportant de nouvelles fonctionnalités, ou améliorant les performances des produits de la génération précédente. Les progrès réalisés peuvent être quantifiés par exemple en terme de vitesse de fonctionnement, encombrement, autonomie et consommation d'énergie. La conception des cartes électroniques incluant ces contraintes est alors délicate. En effet, l'intégration de nouvelles fonctions tout comme la miniaturisation des produits entraînent une densification du circuit imprimé. Le nombre de couches utilisé augmente, l'isolement entre les signaux diminue, l'utilisation de circuits intégrés comportant différentes fonctions comme les SOC ou les SIP entraîne une multiplication du nombre de potentiels d'alimentation. L'augmentation des performances des systèmes impliquent une élévation du taux de débits de données circulant au sein du circuit imprimé et par conséquent l'augmentation des fréquences d'horloge et des signaux. Ces contraintes entraînent l'apparition de problèmes de compatibilité électromagnétique, d'intégrité du signal et d'intégrité de puissance. Il est alors nécessaire de limiter les risques de dysfonctionnement de la carte par une maîtrise des phénomènes qui se produisent d'une part par une analyse de dimensionnement précise afin d'éliminer ou de réduire les problèmes au plus tôt dans la phase de conception et d'autre part en effectuant des simulations de validation une fois la carte terminée. Cette thèse proposée par la société Thales Communications and Security en collaboration avec le laboratoire des Systèmes et Applications des Technologies de l'Information et de l’Énergie (SATIE) de l’École Normale Supérieure de Cachan dans le cadre d'une Convention Industrielle de Formation par la REcherche (CIFRE) a pour but le développement d'une méthodologie d'analyse et de conception du réseau du distribution d'énergie de cartes numériques complexes dans le but de garantir leur fonctionnement sans, ou en réduisant le nombre d'itérations de prototypage. L'introduction au contexte, une description du système étudié et des phénomènes physiques régissant son fonctionnement ainsi qu'un état de l'art des techniques d'analyse d'intégrité de puissance constituent le premier chapitre de ce mémoire. La présentation du véhicule de test, support de tous les résultats de mesure, conçu durant la deuxième année de thèse est l'objet du second chapitre. Ce chapitre dénombre et décrit l'ensemble des scenarii et des réalisations créés pour la mesure des phénomènes propres à l'intégrité de puissance et la corrélation de résultats de simulation avec ceux obtenus en mesure. Dans une troisième partie, les techniques de modélisations de chaque élément constituant le réseau de distribution d'énergie sont décrites. Afin de démontrer la validité des modèles utilisés, les résultats de simulation obtenus pour chaque élément ont été confrontés à des résultats de mesure. Le quatrième chapitre présente la méthodologie de conception et d'analyse de la stabilité des alimentations développée suite aux résultats obtenus des différentes techniques de modélisation. Les outils utilisés sont précisément décrits et les résultats de simulation confrontés à ceux de mesure du système complet du véhicule de test. Dans le chapitre 5, l'intérêt de la modélisation des réseaux de distribution d'énergie sera étendu aux études d'intégrité du signal en démontrant comment son inclusion aux simulations permet d'obtenir, lors de la mise en œuvre de co-simulations, des résultats de simulation plus proches de la réalité. Enfin, la dernière partie de ce document synthétise les travaux de la thèse, porte un regard critique et propose quelques perspectives de travaux futurs. / Today's economical context leads electronics and high-tech corporations not only to innovate with a sustained rhythm but also to reduce the design cycle of new products. In order to remain competitive, these corporations must release regularly new products with new functionalities or enhancing performances of the last generation of this product. The enhancement from one generation of the product to the other can be quantified by the speed of execution of a task, the package size or form factor, the battery life and power consumption.The design methodology following these constraints is thus very tough. Indeed, integration of new functionalities as miniaturization of products imply a densification of the printed circuit board. The number of layer in the stack up is increased, isolation between nets is reduced, the use of integrated circuits embedding different functions as SOC or SIP implies a multiplication of the number of voltages. Moreover the increase of circuit performances implies a increasing data rate exchanged between component of the same printed circuit board and occasioning a widening of the reference clock and signal frequency spectrum. These design constraints are the root cause of the apparition of electromagnetic compatibility, signal integrity and power integrity issues. Failure risks must then be limited by fully understanding phenomenon occurring on the board by, on one side, realizing a precise dimensioning pre layout analysis aiming the elimination or reduction of the issues at the beginning of the design cycle, and on the other side, validating the layout by post layout simulation once the printed circuit board routed.This study proposed by Thales Communication and Security in collaboration with public research laboratory SATIE (System and Application of Energy and Information Technologies) of Ecole Normale Supérieure de Cachan within a industrial convention for development through research aims to develop a design methodology for power delivery network of digital printed circuit board with the goal of ensuring good behavior without or by reducing the number of prototypes.The first chapter of this manuscript include an introduction to the context of the study, a precise description of the studied system and the physical phenomenon ruling its behavior, and finally a state of the art of the power integrity technique analysis. A presentation of the test vehicle, designed during the work and support of all measurement results will constitute the focus of second chapter. This chapter presents and describes all the scenarios and implementations created for the observation and measurement of Power Integrity phenomenon and realise measurement-simulation results correlation. In a third part, modeling techniques of each element of the Power Delivery Network are described. The validity of the models is proven by correlating simulation results of each element with measurement results. The fourth chapter presents the analysis and design methodology developed from the results of the different modeling techniques presented in the previous chapter. Simulation tools and their configuration are precisely described and simulation results are compared with measurement results obtained on the test vehicle for the whole system. In the fifth chapter, the interest of power delivery network model will be extended to signal integrity analysis demonstrating how including this model allows to obtain simulation results closer from measurement results by running Signal Integrity Power aware simulation. Finally, the last part of this document synthetizes the work realized and presented in this document, takes a critical look on it and proposes future works and orientations to extend knowledges and understanding of Power Integrity Phenomenon.
17

Automatická analýza dopravy z videa: Rozpoznání typů vozidel a automatické měření rychlosti / Automatic Traffic Video Surveillance: Fine-Grained Recognition of Vehicles and Automatic Speed Measurement

Sochor, Jakub January 2018 (has links)
V rámci této dizertační práce se zaměřuji na Inteligentní dopravní systémy a Počítačové vidění - především automatické měření rychlosti a rozpoznání automobilů podle typů.  Rozpoznání automobilů podle typů je úkol, ve kterém system má predikovat přesný typ (např. Škoda Octavia combi mk2) pro daný obrázek automobilu. Publikoval jsem dva články, které popisují navržený přístup k tomuto problému a tvoří jádro této dizertace. Prezentovaná metoda je založena na 3D obalových kvádrech postavených okolo automobilů, které jsou následně využity pro rozbalení obrázku automobilu do roviny a tudíž normalizaci vstupu neuronové sítě, která dělá následné rozpoznání. Přístup byl dále rozpracován v druhé publikaci, kde je navržena metoda pro určení tohoto 3D obalového kvádru z jediného obrázku - tudíž není nutné mít zkalibrovanou kameru. Experimentální výsledky ukazují, že navržená metoda zlepšuje úspěšnost rozpoznání o 12 procentních bodů - chyba rozpoznání je redukována o 50 procent.Při měření rychlosti má systém za úkol odhadnout rychlost projíždějících aut z videa. Cílem je také, ať měření probíhá plně automaticky bez jakékoli manuální kalibrace. Jelikož neexistoval žádný dataset, který by obsahoval velké množství průjezdů s přesně změřenou rychlostí, tak jsme nejprve takovýto dataset pořídili. Dále jsem navrhnul metodu pro plně automatickou kalibraci dopravní dohledové kamery což umožňuje měřit rychlost automobilů pozorovaných touto kamerou. Metoda je založena na odhadu kalibrace pomocí detekovaných úběžníků scény a následného zarovnání 3D modelů několika běžných typů automobilů. Experimentální výsledky ukazují, že navržená metoda dosahuje průměrné chyby měření rychlosti 1,10 km/h.
18

The fitting of statistical distributions to wind data in coastal areas of South Africa

Moodley, Kirshnee January 2012 (has links)
Coastal South African cities like Port Elizabeth are said to have a strong potential for wind energy. This study aims to model wind data in order to be able assess the power potential belonging to a given site. The main challenge in modelling wind direction data is that it is categorized as circular data and therefore requires special techniques for handling that are different from usual statistical samples. Statistical tools such as descriptive measures and distribution fitting, were re-invented for directional data by researchers in this field. The von Mises distribution is a predominant distribution in circular statistics and is commonly used to describe wind directions. In this study, the circular principles described by previous researchers were developed by using the statistical software, Mathematica. Graphical methods to present the wind data were developed to give an overview of the behaviour of the winds in any given area. Data collected at Coega, an area near Port Elizabeth, South Africa, was used to illustrate the models which were established in this study. Circular distributions were fit to the directional data in order to make appropriate conclusions about the prevailing wind directions in this area.
19

The fitting of statistical distributions to wind data in coastal areas of South Africa

Moodley, Kirshnee January 2013 (has links)
Coastal South African cities like Port Elizabeth are said to have a strong potential for wind energy. This study aims to model wind data in order to be able assess the power potential belonging to a given site. The main challenge in modelling wind direction data is that it is categorized as circular data and therefore requires special techniques for handling that are different from usual statistical samples. Statistical tools such as descriptive measures and distribution fitting, were re-invented for directional data by researchers in this field. The von Mises distribution is a predominant distribution in circular statistics and is commonly used to describe wind directions. In this study, the circular principles described by previous researchers were developed by using the statistical software, Mathematica. Graphical methods to present the wind data were developed to give an overview of the behaviour of the winds in any given area. Data collected at Coega, an area near Port Elizabeth, South Africa, was used to illustrate the models which were established in this study. Circular distributions were fit to the directional data in order to make appropriate conclusions about the prevailing wind directions in this area.
20

Měření rychlosti vozidel s použitím radaru / Speed Measuring of Vehicles Using Radar

Vlkovič, Vladimír January 2017 (has links)
This masters thesis is focused around the designing and implementation of an anpplication that can extract information on speed of vehicles from radar data. The radar measurements were done by using a continous wave radar. The emphasis is placed on the computation of the angle in which the car approaches the radar and on the speed correction based on this angle. The final design was implemented in Matlab. The evaluation of the implemented solution was done on reference data.

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