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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

Um método para identificação de parâmetros modais em tempo real / A method for modal parameters identification in real time

Rebolho, Daniela Cristina 19 April 2006 (has links)
Na Indústria Aeronáutica, é de extrema importância a qualidade e o desempenho de seus produtos, que estão diretamente relacionados ao projeto e ao desenvolvimento de estruturas adequadas, pois além de seu caráter funcional deve-se também garantir a sua integridade nas mais diversas condições de operação. O comportamento dinâmico destas estruturas é um dos seus principais aspectos, principalmente devido à demanda contínua para estruturas mais leves e consequentemente mais flexíveis. Tradicionalmente, as estruturas aeroespaciais devem ser submetidas a alguma forma de verificação antes do voo, de forma a assegurar que a aeronave esteja livre de qualquer fenômeno de instabilidade aeroelástica, que pode ocorrer provocando problemas de fadiga ou falhas estruturais. Um dos fenômenos de instabilidade mais importantes é denominado flutter. As técnicas de ensaio em voo para identificação de flutter são de extrema importância para o conhecimento dos limites de voo seguro. Um dos elementos essenciais para a realização de ensaios de flutter em voo é o processo de identificação dos parâmetros modais estruturais da aeronave sob teste. A identificação precisa e rápida dos parâmetros modais permite determinar com antecedência e segurança as condições de voo em que o fenômeno de flutter irá ocorrer. Atualmente as pesquisas nesta área apontam na direção do desenvolvimento de tecnologia que permita a identificação em tempo real dos parâmetros modais associados ao flutter. Neste trabalho foi realizado o estudo de um método de identificação de parâmetros modais para ser aplicado em tempo real. O método de identificação utilizado para este estudo é o EERA - Extended Eigensystem Realization Algorithm, um método de identificação no domínio do tempo considerado eficiente e poderoso, pois é capaz de identificar o comportamento dinâmico complexo em estruturas. O algoritmo foi validado através de um ensaio experimental num modelo de asa no túnel de vento, onde foram determinados os parâmetros modais envolvidos no flutter. Também foi realizado um ensaio experimental numa placa de alumínio, onde foram identificados os seus parâmetros modais, frequências naturais e fatores de amortecimento. Após sua validação, o método EERA foi adaptado e programado no equipamento de aquisição e processamento de sinais dSPACE®, que é destinado a realizar identificação em tempo real. Por último foi realizado um ensaio experimental em tempo real na placa de alumínio utilizada anteriormente, onde os parâmetros modais identificados on-line foram comparados com os identificados off-line, comprovando assim a eficiência do método na identificação em tempo real. / In the Aeronautical Industry, the quality and the performance of its products, that are directly related to the project and the development of adequate structures, are of extreme importance, since, beyond their functional characteristics, their integrity, in the most diverse operation conditions, must also be guaranteed. The dynamic behavior of these structures is one of its main aspects, mainly due to continuous demand for lighter and consequently more flexible structures. Traditionally, the aerospace structures must be submitted to some form of verification before the flight, to assure that the aircraft is free of any aeroelastic instability phenomenon, which when occurring will provoke structural fatigue problems or failure. One of the more important instability phenomena is called flutter. The techniques of flight test for identification of flutter are of extreme importance for the knowledge of the limits of safe flight. One of the essential elements for the accomplishment of flutter tests in flight is the process of identification of the structural modal parameters of the aircraft under test. The accurate and fast identification of the modal parameters allows determining, with antecedence and security, the flight conditions where the phenomenon of flutter will occur. Currently the research in this area points in the direction of developing the technology that allows the identification in real time of the modal parameters associated to flutter. In this work the study of a method of identification of modal parameters was carried through to be applied in real time. The method of identification used for this study is the EERA - Extended Eigensystem Realization Algorithm, a method of identification in the time domain considered efficient and powerful, since it is capable to identifying complex dynamic behavior in structures. The algorithm was validated with an experimental test in a model of wing in the wind tunnel, where the involved modal parameters in flutter had been determined. Also an experimental test was carried out with an aluminum plate, where its modal parameters, natural frequencies and damping factors, had been identified. After its validation, the method EERA was adapted and programmed in the dSPACE® signals acquisition and processing equipment, which is used for carrying out identification in real time. Finally an experimental test, in real time, with the previously used aluminum plate was carried out, when the modal parameters identified on-line were compared with those identified off-line, thus proving the efficiency of the method for identification in real time.
2

RFID technologie a její použití ve zvoleném podniku / RFID Technology and its Use in Selected Enterprise

Brožová, Natálie January 2016 (has links)
This thesis focuses on the topic of RFID - radio frequency identification of objects. The theoretical part is focused on the definition and history of RFID systems, the main components of this technology, regulation and standards in the use of RFID, categories of RFID and its implementing into business processes. The theoretical part also describes the costs of RFID, potential benefits arising from its implementation and examples of areas in which RFID technology is applied. The practical part deals with the implementation of RFID in a particular company and describes situation of the company before and after the RFID implementation. Furthermore, practical part summarizes the results of interviews with employees of the company and a listing of key benefits that RFID has brought. At the end of the practical part the author proposes some improvements to the existing use of RFID system.
3

Um método para identificação de parâmetros modais em tempo real / A method for modal parameters identification in real time

Daniela Cristina Rebolho 19 April 2006 (has links)
Na Indústria Aeronáutica, é de extrema importância a qualidade e o desempenho de seus produtos, que estão diretamente relacionados ao projeto e ao desenvolvimento de estruturas adequadas, pois além de seu caráter funcional deve-se também garantir a sua integridade nas mais diversas condições de operação. O comportamento dinâmico destas estruturas é um dos seus principais aspectos, principalmente devido à demanda contínua para estruturas mais leves e consequentemente mais flexíveis. Tradicionalmente, as estruturas aeroespaciais devem ser submetidas a alguma forma de verificação antes do voo, de forma a assegurar que a aeronave esteja livre de qualquer fenômeno de instabilidade aeroelástica, que pode ocorrer provocando problemas de fadiga ou falhas estruturais. Um dos fenômenos de instabilidade mais importantes é denominado flutter. As técnicas de ensaio em voo para identificação de flutter são de extrema importância para o conhecimento dos limites de voo seguro. Um dos elementos essenciais para a realização de ensaios de flutter em voo é o processo de identificação dos parâmetros modais estruturais da aeronave sob teste. A identificação precisa e rápida dos parâmetros modais permite determinar com antecedência e segurança as condições de voo em que o fenômeno de flutter irá ocorrer. Atualmente as pesquisas nesta área apontam na direção do desenvolvimento de tecnologia que permita a identificação em tempo real dos parâmetros modais associados ao flutter. Neste trabalho foi realizado o estudo de um método de identificação de parâmetros modais para ser aplicado em tempo real. O método de identificação utilizado para este estudo é o EERA - Extended Eigensystem Realization Algorithm, um método de identificação no domínio do tempo considerado eficiente e poderoso, pois é capaz de identificar o comportamento dinâmico complexo em estruturas. O algoritmo foi validado através de um ensaio experimental num modelo de asa no túnel de vento, onde foram determinados os parâmetros modais envolvidos no flutter. Também foi realizado um ensaio experimental numa placa de alumínio, onde foram identificados os seus parâmetros modais, frequências naturais e fatores de amortecimento. Após sua validação, o método EERA foi adaptado e programado no equipamento de aquisição e processamento de sinais dSPACE®, que é destinado a realizar identificação em tempo real. Por último foi realizado um ensaio experimental em tempo real na placa de alumínio utilizada anteriormente, onde os parâmetros modais identificados on-line foram comparados com os identificados off-line, comprovando assim a eficiência do método na identificação em tempo real. / In the Aeronautical Industry, the quality and the performance of its products, that are directly related to the project and the development of adequate structures, are of extreme importance, since, beyond their functional characteristics, their integrity, in the most diverse operation conditions, must also be guaranteed. The dynamic behavior of these structures is one of its main aspects, mainly due to continuous demand for lighter and consequently more flexible structures. Traditionally, the aerospace structures must be submitted to some form of verification before the flight, to assure that the aircraft is free of any aeroelastic instability phenomenon, which when occurring will provoke structural fatigue problems or failure. One of the more important instability phenomena is called flutter. The techniques of flight test for identification of flutter are of extreme importance for the knowledge of the limits of safe flight. One of the essential elements for the accomplishment of flutter tests in flight is the process of identification of the structural modal parameters of the aircraft under test. The accurate and fast identification of the modal parameters allows determining, with antecedence and security, the flight conditions where the phenomenon of flutter will occur. Currently the research in this area points in the direction of developing the technology that allows the identification in real time of the modal parameters associated to flutter. In this work the study of a method of identification of modal parameters was carried through to be applied in real time. The method of identification used for this study is the EERA - Extended Eigensystem Realization Algorithm, a method of identification in the time domain considered efficient and powerful, since it is capable to identifying complex dynamic behavior in structures. The algorithm was validated with an experimental test in a model of wing in the wind tunnel, where the involved modal parameters in flutter had been determined. Also an experimental test was carried out with an aluminum plate, where its modal parameters, natural frequencies and damping factors, had been identified. After its validation, the method EERA was adapted and programmed in the dSPACE® signals acquisition and processing equipment, which is used for carrying out identification in real time. Finally an experimental test, in real time, with the previously used aluminum plate was carried out, when the modal parameters identified on-line were compared with those identified off-line, thus proving the efficiency of the method for identification in real time.
4

Automated fish detection and identification / Détection et identification automatique de poissons

Wong, Poh Lee 04 September 2015 (has links)
L’utilisation de techniques informatiques pour la reconnaissance et l'identification des poissons est devenue assez populaire parmi les chercheurs. Ces nouvelles approches sont importantes, puisque les informations extraites sur les poissons telles que leurs trajectoires, leurs positions ou leurs couleurs, permettent de déterminer si les poissons sont en bonne santé ou en état de stress. Les méthodes existantes ne sont pas assez précises notamment lorsque des éléments tels que les bulles ou des zones éclairées peuvent être identifiées comme étant des poissons. De plus, les taux de reconnaissance et d'identification des systèmes existants peuvent encore être améliorés afin d’obtenir des résultats à la fois meilleurs et plus précis. Afin d’obtenir de meilleurs taux de reconnaissance et d'identification, un système amélioré a été construit en combinant plusieurs méthodes de détection et d’analyse. Tout d'abord, la première étape a consisté à proposer une méthode de suivi d'objets dans le but de localiser en temps réel la position des poissons à partir de vidéos. Celle-ci inclut le suivi automatisé multi-cibles de poissons dans un aquarium. Les performances en termes de détection et d’identification risquaient d’être faibles notamment en raison du processus de suivi dans un environnement temps réel. Une méthode de suivi des poissons plus précise est donc proposée ainsi qu'une méthode complète pour identifier et détecter les modèles de nage des poissons. Dans ces travaux, nous proposons, pour le suivi des poissons, une amélioration de l’algorithme du filtre particulaire en l’associant à un algorithme de détection de mouvement. Un système doté de deux caméras est également proposé afin d'obtenir un meilleur taux de détection. La seconde étape comprend la conception et le développement d'une méthode améliorée pour le recadrage et la segmentation dynamique des images dans un environnement temps réel. Ce procédé est proposé pour extraire de la vidéo les images représentant les poissons en éliminant les éléments provenant de l’arrière-plan. La troisième étape consiste à caractériser les objets (les poissons). La méthode proposée est basée sur des descripteurs utilisant la couleur pour caractériser les poissons. Ces descripteurs sont ensuite utilisés dans la suite des traitements. Dans nos travaux, les descripteurs couleurs généralisés de Fourier (GCFD : Generalized Color Fourier Descriptor) sont utilisés et une adaptation basée sur la détection de l’environnement est proposée afin d’obtenir une identification plus précise des poissons. Une méthode de mise en correspondance basée sur un calcul de distance est utilisée pour comparer les vecteurs de caractéristiques des images segmentées afin de classifier les poissons présents dans la vidéo. Un prototype dont le but est de modéliser les profils de nage des poissons a été développé. Celui-ci intègre toutes les méthodes proposées et a permis d’évaluer la validité de notre approche. Les résultats montrent que les méthodes proposées améliorent la reconnaissance et l’identification en temps réel des poissons. La méthode de suivi proposée montre une amélioration par rapport au procédé basé sur le filtre particulaire classique. Le recadrage dynamique et la méthode de segmentation temps-réel présentent en termes de précision un pourcentage moyen de 84,71%. La méthode de caractérisation des objets développée pour reconnaitre et identifier en temps réel les poissons montre également une amélioration par rapport aux descripteurs couleurs classiques. Le travail réalisé peut trouver une application directe auprès des aquaculteurs afin de suivre en temps réel et de manière automatique le comportement des poissons et éviter ainsi un suivi « visuel » tel qu’il est réalisé actuellement. / Recognition and identification of fish using computational methods have increasingly become a popular research endeavour among researchers. The methods are important as the information displayed by the fish such as trajectory patterns, location and colour could determine whether the fish are healthy or under stress. Current methods are not accurate especially when there exist thresholds such as bubbles and some lighted areas which might be identified as fish. Besides, the recognition and identification rate of the existing systems can still be improved to obtain better and more accurate results. In order to achieve a better recognition and identification rate, an improved scheme consisting of a combination of several methods is constructed. First of all, the first approach is to propose an object tracking method for the purpose of locating the position of fish for real-time videos. This includes the consideration of tracking multiple fish in a single tank in an automated way. The detection and identification rate may be slow due to the on-going tracking process especially in a real-time environment. A more accurate fish tracking method is proposed as well as a systematic method to identify and detect fish swimming patterns. In this research, the particle filter algorithm is enhanced and further combined with the motion detection algorithm for fish tracking. A dual camera system is also proposed to obtain better detection rate. The second approach includes the design and development of an enhanced method for dynamically cropping and segmenting images in real-time environment. This method is proposed to extract each image of the fish from every successive video frame to reduce the tendency of detecting the background as an object. The third approach includes an adapted object characterisation method which utilises colour feature descriptors to represent the fish in a computational form for further processing. In this study, an object characterisation method, GCFD (Generalized Colour Fourier Descriptor) is adapted to suit the environment for more accurate identification of the fish. A feature matching method based on distance matching is used to match the feature vectors of the segmented images for classifying the specific fish in the recorded video. In addition, a real-time prototype system which models the fish swimming pattern incorporating all the proposed methods is developed to evaluate the methods proposed in this study. Based on the results, the proposed methods show improvements which result in a better real-time fish recognition and identification system. The proposed object tracking method shows improvement over the original particle filter method. Based on the average percentage in terms of the accuracy for the dynamic cropping and segmentation method in real time, an acceptable value of 84.71% was recorded. The object characterisation method which is adapted for fish recognition and identification in real time shows an improvement over existing colour feature descriptors. As a whole, the main output of this research could be used by aquaculturist to track and monitor fish in the water computationally in real-time instead of manually.
5

Controle de posição de um robô cartesiano por meio de técnicas adaptativas / Position control of a cartesian robot through adaptives techniques

Vale, Valentina Alessandra Carvalho do 18 August 2011 (has links)
Made available in DSpace on 2015-05-08T14:59:33Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1500049 bytes, checksum: 6ca75eb148e850e602c9b480f4d4015c (MD5) Previous issue date: 2011-08-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This paper presents a design of a predictive adaptive controller and a hybrid controller for a electro pneumatic manipulator robot with three Cartesian degrees of freedom (3 DOF). The manipulator robot is composed by three electro-pneumatic valves and pneumatic cylinders for three, two with 500mm forming the XZ axis and a 400mm on the vertical axis Y. The cylinders are driven by three electro-pneumatic proportional valves controlled by computer, which directs the flow of compressed air as the needed position. Attached to the rods of each cylinder, there are scales for potentiometric measurement of their respective positions. Through two acquisition boards, electro-pneumatic valves and potentiometric scales are connected to the computer and the data is processed using the software LabVIEW® and MATLAB®. The controllers are developed through explicit models of the electropneumatic manipulator robot estimated in real time by Recursive Least Squares Algorithm (RLS). / Neste trabalho apresentam-se projetos de um controlador adaptativo preditivo e de um híbrido para um robô manipulador eletropneumático de três graus de liberdade (3 GDL) cartesiano. O robô manipulador é composto basicamente por três válvulas eletropneumáticas e por três cilindros pneumáticos, dois de 500mm formando o plano XZ e um de 400mm no eixo vertical Y. Os cilindros são acionados através de três válvulas eletropneumáticas proporcionais comandadas por computador, que direcionam o fluxo de ar comprimido conforme a necessidade de posicionamento. Acopladas às hastes de cada cilindro, estão réguas potenciométricas para medição de suas respectivas posições. Através de duas placas de aquisição, as válvulas eletropneumáticas e as réguas potenciométricas são conectadas ao computador e os dados são processados utilizando os softwares LabVIEW® e Matlab®. Os controladores são desenvolvidos através de modelos explícitos do robô manipulador eletropneumático estimados em tempo real pelo Algoritmo dos Mínimos Quadrados Recursivo (MQR).
6

Étude et élaboration d’un système de surveillance et de maintenance prédictive pour les condensateurs et les batteries utilisés dans les Alimentations Sans Interruptions (ASI) / Study and elaboration of a monitoring and predictive maintenance system for capacitors and batteries used in Uninterruptible Power Supplies (UPS)

Abdennadher, Mohamed Karim 25 June 2010 (has links)
Pour assurer une énergie électrique de qualité et de façon permanente, il existe des systèmes électroniques d’alimentation spécifiques. Il s’agit des Alimentations Sans Interruptions (ASI). Une ASI comme tout autre système peut tomber en panne ce qui peut entrainer une perte de redondance. Cette perte induit une maintenance corrective donc une forme d’indisponibilité ce qui représente un coût. Nous proposons dans cette thèse de travailler sur deux composants parmi les plus sensibles dans les ASI à savoir les condensateurs électrolytiques et les batteries au plomb. Dans une première phase, nous présentons, les systèmes de surveillance existants pour ces deux composants en soulignant leurs principaux inconvénients. Ceci nous permet de proposer le cahier des charges à mettre en œuvre. Pour les condensateurs électrolytiques, nous détaillons les différentes étapes de caractérisation et de vieillissement ainsi que la procédure expérimentale de vieillissement standard accéléré et les résultats associés. D’autre part, nous présentons les résultats de simulation du système de surveillance et de prédiction de pannes retenu. Nous abordons la validation expérimentale en décrivant le système développé. Nous détaillons les cartes électroniques conçues, les algorithmes mis en œuvre et leurs contraintes d’implémentation respectifs pour une réalisation temps réel. Enfin, pour les batteries au plomb étanches, nous présentons les résultats de simulation du système de surveillance retenu permettant d’obtenir le SOC et le SOH. Nous détaillons la procédure expérimentale de vieillissement en cycles de charge et décharge de la batterie nécessaire pour avoir un modèle électrique simple et précis. Nous expliquons les résultats expérimentaux de vieillissement pour finir avec des propositions d’amélioration de notre système afin d’obtenir un SOH plus précis. / To ensure power quality and permanently, some electronic system supplies exist. These supplies are the Uninterrupted Power Supplies (UPS). An UPS like any other system may have some failures. This can be a cause of redundancy loss. This load loss causes a maintenance downtime which may represent a high cost. We propose in this thesis to work on two of the most sensitive components in the UPS namely electrolytic capacitors and lead acid batteries. In a first phase, we present the existing surveillance systems for these two components, highlighting their main drawbacks. This allows us to propose the specifications which have to be implemented for this system. For electrolytic capacitors, we detail different stages of characterization ; the aging accelerated standard experimental procedure and their associated results. On the other hand, we present the simulation results of monitoring and failure prediction system retained. We discuss the experimental validation, describing the developed system. We detail the electronic boards designed, implemented algorithms and their respective constraints for a real time implementation. Finally, for lead acid batteries, we present the simulation results of the monitoring system adopted to obtain the SOC and SOH. We describe the aging experimental procedure of charging and discharging cycles of the batteries needed to find a simple and accurate electric models. We explain the aging experimental results and in the end we give suggestions for improving our system to get a more accurate SOH.

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