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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.
231

Contribution à la commande et l'observation des systèmes dynamiques continus sous mesures clairsemées / Contribution to the observation and control of continuous systems under sparse measurements

Khaled, Yassine 13 June 2014 (has links)
Les travaux de cette thèse portent sur l'analyse de stabilité des systèmes dynamiques impulsionnels et la synthèse d'observateurs pour les systèmes dynamiques continus avec mesures discrètes.On considère que les mesures sont prises d'une façon aléatoire pour éviter la perte d'observabilité et on montre que la synthèse d'un observateur impulsionnel couplé avec un observateur classique continu via un gain est une solution pertinente pour reconstruire l'état continu du système et commander et stabiliser ces systèmes par un retour d'état basé sur ces observateurs. De plus, ce nouveau schéma d'observateur (impulsionnel couplé avec observateur classique continu) permet de reconstruire le vecteur de sortie même si les mesures prises ne vérifient pas les conditions du Shannon-Nyquist. Ensuite, un chapitre est dédié à la détection de mode actif et à la reconstruction de son état associé, ceci pour une classe de systèmes linéaires hybrides sous mesures clairsemées. La solution que nous avons apportée à ce problème est d'une part l'analyse d'observabilité des systèmes sous échantillonnage aléatoire et d'autre part la synthèse d'observateurs impulsionnels. Ici, la première approche est basée sur le concept d'échantillonnage compressif bien connu en théorie du traitementdu signal. Une synthèse d'observateurs impulsionnels a été présentée pourquelques cas particuliers.D'autre part, une nouvelle méthode de synthèse d'observateurs spécifique aux systèmes non linéaire continus avec mesures discrètes est également proposée. Cette méthode utilise la condition de Lipchitz pour la transformation d'un système non linéaire à un système linéaire à paramètres variants basée sur l'utilisation du théorème des accroissements finis afin de synthétiser des observateurs impulsionnels.Enfin, les observateurs proposés sont testés sur une application à la synchronisation de systèmes chaotiques dédiés à la communication sécurisée. / This thesis deals with the stability analysis of impulsive systems and the design of impulsive observers for systems under sparse measurements.The measures are sparse but random in order to avoid the loss of observability.Moreover, it is highlighted that the synthesis of an impulsive observer coupled with a classical continuous observer via an observer gain is an appropriate solution to reconstruct the continuous system state and to stabilize this system by state feedback based on these observers. In addition, this new scheme (impulsive observer coupled with classical observer) can reconstruct the output vector, even if the available measurement do not verify the Nyquist-Shannon conditions. Another part is dedicated to the detection of the active mode and to the estimation of the associated continuous state for a class of linear hybrid systems under sparse measurements. The solution we found to this problem is firstly the observability of systems under random sampling and secondly the design of an impulsive observer. Here, the first approach is based on the concept of compressive sensing theory well known in signal processing. The design of the impulsive observer is presented for some special classes of nonlinear systems.Moreover, a novel observer design method for continuous nonlinear systems withdiscrete measurements is proposed. This method uses the Lipchitz conditions andthe mean value theorem in order to transform the problem in a linear one.Finally, the proposed observer are tested on application to the synchronization of chaotic systems dedicated to the secure communications
232

Observateurs d'état pour le diagnostic de comportement dynamique de véhicules automobiles en environnement réel de conduite / State observer for diagnosis of dynamic behavior of vehicle in its environment

Wang, Bin 11 December 2013 (has links)
Le contrôle de stabilité est un sujet essentiel dans les systèmes avancés d’aide à la conduite développés par les constructeurs et équipementiers automobiles. Les systèmes de sécurité actifs sont devenus un standard dans les véhicules particuliers, tels que : le contrôle électronique de la stabilité (ESC) et le système de contrôle de traction (TCS). La description du comportement dynamique du véhicule pendant le mouvement, est fondamental dans le fonctionnement des nouveaux systèmes de sécurité active. Certains systèmes actifs sont déjà implémentés dans des véhicules standards comme des options supplémentaires, pour améliorer la sécurité sur la route ou pour le confort du conducteur et des passagers. Cependant, ces systèmes ont besoin d’informations sur la dynamique de véhicule, qui représente les caractéristiques de mouvement du véhicule sur la route. L’accès à ces informations est souvent difficile, pour des raisons technologiques ou économiques. De ce fait, nous développons des algorithmes, basés sur la technique d’observation d’état, pour estimer une partie de ces variables notamment, les efforts dynamiques du contact pneumatique/chaussée et l’angle de dérive dans son environnement. En revanche, ces systèmes sont conçus pour faire face à l’état actuel du véhicule où la situation de danger a toujours eu lieu, la capacité de ces systèmes est limitée à minimiser les effets de danger. L’objectif ultime est de prévoir et d’éviter efficacement un accident avant qu’il se produise. Par conséquent, ce travail est dédié aussi à développer une méthode de prédiction des risques pour rappeler au conducteur la vitesse de sécurité pour négocier les virages à venir. Dans un premier temps, nous développons dans ce mémoire une nouvelle approche pour estimer la répartition de la charge verticale sur chaque roue dans un environnement réel. L’influence de l’angle de pente est considérée dans la phase de reconstruction du modèle du véhicule. Les forces verticales sont estimées en utilisant un filtre de Kalman. Afin d’estimer la force latérale du pneu, un filtre de Kalman entendu et un filtre Particulaire ont appliqués pour tenir compte des non-linéarités du modèle de véhicule. Deux techniques différentes d’observateurs sont proposées et comparées avec des données expérimentales. Dans un deuxième temps, nous étendons, à l’instant futur, la prise en compte de l’évaluation de risque d’accidents. La prédiction des paramètres de la dynamique du véhicule, l’évaluation du risque potentiel ainsi que la détermination d’une vitesse d’alerte à l’approche des virages, sont introduites pour réduire le risque potentiel d’accident dans les virages. Enfin, la dernière partie du mémoire est consacrée à l’application en temps réel, sur un véhicule démonstrateur, du processus d’observation d’état développé précédemment. Les résultats expérimentaux sont réalisés pour démontrer la performance des estimateurs intégrés en temps réel. / Nowadays, a variety of advanced driving assistance systems are being developed by research centers and automobile manufactures. Stability control is an essential topic in the modern industrial automobile society. Driving safety is widely concerned in the passenger cars to prevent potential risks. More and more electronic active safety systems are fitted out as a standard option, such as Electronic Stability Control (ESC) and Traction Control System (TCS). These safety systems are efficient in helping the driver maintain control of the car and also are considered highly cost-effective. However, for the future development trend of these systems, a more complex and integrated control unit requires more information about the vehicle dynamics. Some fundamental parameters such as tire road forces and sideslip angle are effective in describing vehicle dynamics. Nevertheless, it is lacking an effective and low-cost sensor to measure directly. Therefore, this study presents amethod to estimate these parameters using observer technologies and low-cost sensors which are available on the passenger cars in real environment. In addition, these systems are designed for dealing with vehicle current state where danger situation has always occurred, the capacity of these systems is limited to minimize the effects. We were wondering whether shall we predict and effectively avoid a crash before it occurred. Therefore, this work is also addressed to develop a risk prediction method for proposing driver a safe speed to negotiate the upcoming curves. First, this dissertation develops a new approach to estimate the vertical load distribution in real environment. The influence of bank angle is considered in the phase of reconstruction of vehicle model. The vertical tire force on banked road is estimated by using Kalman filter. In order to estimate the lateral tire force, two nonlinear observers are addressed to solve the nonlinearity of vehicle model. The Extended Kalman filter is widely discussed in the previous literature, while we firstly use a Particle filter to estimate the vehicle dynamics parameters. Two different observer technologies are proposed and compared using the experimental data. Second, extending the consideration of road safety to the future instant. Prediction of vehicle dynamics parameters, evaluation of potential risk as well as establishment of advisory speed on curves are introduced to reduce the possibility of crash occurrence on curves. Last but not least, the real-time sampling and process system is presented, the estimator with EKF and PF has been developed as a real-time application. Experimental results are performed to demonstrate the performance of these integrated systems in real-time.
233

Low-Dose 3D Quantitative Vascular X-ray Imaging of the Breast / Imagerie Vasculaire du Sein par Rayons X, Tridimensionnelle, Quantitative et Faible Dose

Milioni de Carvalho, Pablo 22 September 2014 (has links)
Contexte : Le cancer du sein est le cancer le plus fréquent et le deuxième cancer le plus mortel chez la femme. Les techniques d'imagerie constituent un élément essentiel pour le dépistage, le diagnostic, la stadification et le traitement du cancer du sein. L'imagerie par résonance magnétique avec injection de produit de contraste (CE-MRI) est actuellement la technique d'imagerie standard pour la détection du développement vasculaire anormal et des prises de contraste des lésions mammaires. CE-MRI est cependant très coûteuse et peu disponible. De plus, sa résolution spatiale pourrait être insuffisante pour la détection de certains types de lésions, et ne permet pas d'imager les amas de microcalcifications. Le développement de l'angiomammographie double-énergie (CESM) a permis l'utilisation des produits de contraste intraveineux en clinique avec des appareils conventionnels de mammographie. Cependant, CESM est une technique de projection 2D et présente, par conséquence, des limites pour décrire la structure 3D interne des lésions et pour fournir une information fonctionnelle 3D précise.La tomosynthèse numérique du sein avec injection de produit de contraste (CE-DBT) et le scanner dédié du sein avec injection de produit de contraste (CE-bCT) sont deux techniques d'imagerie actuellement en investigation par des groupes de recherche académiques et industriels. Il est cependant anticipé que le potentiel quantitatif de la CE-DBT soit limité, en raison de la faible résolution en profondeur due à l'ouverture angulaire limitée de la DBT. CE-bCT, avec sa résolution spatiale quasi-isotrope et son intensité de signal proportionnelle au coefficient d'atténuation linéaire, est supposée offrir une information quantitative plus précise, bien qu'une utilisation à faible dose de radiation reste toujours un défi.Objectifs : L'objectif de cette thèse a été d'étudier la faisabilité de la méthode CE-bCT et sa capacité à détecter et localiser des tumeurs vascularisées, ainsi que d'offrir de l'information morphologique et fonctionnelle précise sur les tumeurs. Pour comprendre la valeur ajoutée de la CE-bCT par rapport à CE-DBT, le potentiel quantitatif des deux méthodes a également été comparé. Nos études ont été réalisées grâce à des simulations par ordinateur, validées par des mesures expérimentales.Méthodes : Dans un premier temps, une plateforme de simulation capable de modéliser différentes techniques d'imagerie du sein par rayons X, et fournissant des images radiographiques de fantômes numériques simples et complexes, a été implémentée et validée. Deuxièmement, une étude d'optimisation pour la technique CE-bCT basée sur une approche double-énergie a été réalisée, dans le but de maximiser la qualité des images équivalentes-iode ainsi que des images morphologiques. Enfin, le potentiel quantitatif des méthodes CE-bCT et CE-DBT a été comparé au travers de l'évaluation de la détectabilité, de la caractérisation, de la localisation et de la mesure de l'étendue 3D des lésions iodées. Dans une étude impliquant des observateurs humains, la détectabilité et la caractérisation des lésions iodées de différentes tailles, formes et concentrations ont été comparées entre CE-bCT et CE-DBT, grâce à l'utilisation d'un fantôme anthropomorphique numérique du sein.Conclusions : Les études de simulation menées pendant cette thèse suggèrent que le scanner dédié du sein avec injection de produit de contraste iodé pourrait être une technique réalisable pour la détection, localisation et caractérisation des tumeurs du sein, pour un niveau de dose comparable à une mammographie standard. Bien que les comparaisons préliminaires avec CE-DBT suggèrent une performance comparable sur la détection et caractérisation, l'information 3D complète combinée avec une haute résolution spatiale font de CE-bCT une évolution intéressante de CESM vers une évaluation quantitative 3D des prises de contraste, et une alternative potentielle à CE-MRI pour certaines indications cliniques. / Background: Worldwide, breast cancer is the most common cancer and second deadliest cancer in women. Diagnostic imaging techniques are a critical part for screening, diagnosis, tumor staging and cancer therapy of the breast. Contrast-Enhanced Magnetic Resonance Imaging (CE-MRI) is the current standard imaging technique allowing detection of abnormal vascular development and lesion contrast uptake. CE-MRI is however very costly and not widely available. Moreover, its spatial resolution might not be sufficient to depict certain types of lesions including microcalcifications. The development of Contrast-Enhanced Spectral Mammography (CESM) has made the clinical use of intravenous contrast enhancement with conventional mammography possible. However, CESM is a 2D projection technique and therefore presents limitations to depict the 3D internal structures of lesions and to provide accurate quantitative 3D functional information.Contrast-Enhanced Digital Breast Tomosynthesis (CE-DBT) and dedicated Contrast-Enhanced Breast CT (CE-bCT) are two breast imaging modalities currently under investigation by academic and industrial research groups. It is however anticipated that the quantitative potential of CE-DBT is limited, due to the inherent low depth-resolution of limited opening angle DBT modality. CE-bCT with quasi-isotropic spatial resolution and voxel signal intensity proportional to the linear attenuation coefficient is believed to offer more accurate quantitative information, though a low-dose operation is still a challenge.Objectives: The purpose of this thesis has been to study the technical feasibility of CE-bCT and its potential to accurately depict and localize tumors, as well as to provide accurate quantitative morphological and functional imaging information about tumors, at low radiation dose levels. To understand the incremental value of CE-bCT over CE-DBT, the quantitative potential of both technologies have been compared. This investigation has been performed through computer simulations.Methods: At first, a simulation platform capable of modeling various X-ray breast imaging techniques and providing radiographic images of simple and complex computational phantoms was developed and validated. Secondly, an optimization study of a CE-bCT technique based on a dual-energy approach was performed, aiming to maximize image quality of iodine-enhanced and morphological images. Finally, the quantitative potential of CE-bCT and CE-DBT was compared through the assessment of iodine-enhanced lesion detectability, characterization, localization and 3D extent measurement. In a human observer study, depiction and characterization of iodine-enhanced lesions of different sizes, shapes and iodine uptakes was compared between CE-bCT and CE-DBT using a mesh-based anthropomorphic breast phantom.Conclusions: The simulation studies in this PhD thesis suggest that dual-energy iodine-injected CE-bCT could be a feasible technique for breast tumor depiction, localization and characterization, with dose levels comparable to standard mammography. While preliminary comparisons with CE-DBT suggests comparable depiction and characterization performance, the fully 3D information combined with high spatial resolution confirms CE-bCT as an interesting low-dose evolution of CESM toward 3D quantitative assessment of contrast uptakes and potential alternative to
234

Avaliação de técnicas calorimétricas aplicadas ao monitoramento de processos químicos. / Calorimetric technique evaluation applied for chemical processes monitoring.

Hirota, Wilson Hideki 01 September 2009 (has links)
A crescente demanda por produtos poliméricos com propriedades cada vez mais estritas tem forçado o desenvolvimento de técnicas de monitoramento em linha cada vez mais precisas e robustas. Infelizmente, grande parte das principais propriedades poliméricas não são quantificáveis em linha a partir das metodologias analíticas atualmente disponíveis e, portanto, na prática, as propriedades finais dos látices poliméricos são obtidas através da caracterização off line de amostras discretas coletadas do processo, resultando em um tempo de análise longo e indesejado para qualquer algoritmo de controle em tempo real. Por outro lado, como as reações de polimerização são altamente exotérmicas é possível quantificar continuamente a taxa de calor gerado pela reação a partir das medidas de temperatura e do balanço de energia que, por sua vez, pode ser usada para obter importantes informações acerca do estado do processo. Entretanto, esta técnica requer a atualização contínua do coeficiente global de troca térmica ao longo da reação, uma vez que este parâmetro está sujeito a variações temporais significativas. Portanto, o presente trabalho tem por objetivo analisar a viabilidade da aplicação conjunta dos conceitos da calorimetria e dos observadores não-lineares para a estimação dos estados de um processo químico. Para isso, serão analisadas duas reações químicas distintas: a) uma reação de hidrólise de anidrido acético, b) uma reação copolimerização em emulsão. Os resultados obtidos mostraram que essa metodologia é extremamente dependente dos parâmetros de sintonia do observador de estado, inviabilizando o seu uso para o monitoramento em linha de um processo químico. Por outro lado, a aplicação direta do balanço de energia para estimação do calor gerado pela reação, mostrou-se uma forma alternativa simples e viável para a estimação em tempo real dos estados de uma reação de polimerização. / The increasing demand for the production of polymers with more tight properties has placed great emphasis on the development of accurate and robust online monitoring techniques of polymerization reactions. Unfortunately, most of the main characteristics are not measurable online from analytical methodologies currently available and, therefore, in practice, the final properties of polymer latexes are obtained through off line characterization of discrete samples collected from the process, resulting in measurement delay which is undesirable for real-time control. On the other hand, since most of the polymerization reactions are highly exothermic, it is possible to quantify continuously the heat release rate based on temperature measurements and energy balance equations that, in turn, can be used to infer valuable information about the state of process. However, this approach requires up-dating the value of the global heat exchange coefficient through reaction, once this parameter is subject to significant time variations. Therefore, this work aims to examine the feasibility of joint implementation of the concepts of reaction calorimetry and nonlinear state observers for estimation of the states of a chemical process. In order to do that, two distinct chemical reactions will be considered: a) a hydrolysis of acetic anhydride reaction, b) an emulsion copolymerization reaction. The results showed that this approach shows a strong dependence of the tuning parameters, preventing its use for online monitoring of a chemical process. On the other hand, applying the heat balance it is possible to infer continuously the heat release rate and the states of polymerization reactions.
235

Controle de velocidade sensorless aplicado ao controle direto de torque da máquina de indução / Sensorless speed control applied to direct torque control of induction machine

Pereira, William César de Andrade 14 February 2014 (has links)
Neste trabalho é apresentado um estudo sobre o controle de velocidade sensorless aplicado ao Motor de Indução Trifásico (MIT) visando sobretudo, melhorar o desempenho da máquina de indução em aplicações na região de baixa frequência de operação. Para tanto, propõe-se uma abordagem utilizando a técnica de controle Direct Torque Control (DTC) com Space Vector Modulation (SVM) em conjunto com o Observador de Fluxo com Modelo de Tensão e Corrente (OFMTC), o que possibilita a estimação precisa da posição do vetor de fluxo do estator em baixa velocidade. Para a estimativa da velocidade do rotor é utilizado a estratégia Model Reference Adaptive System (MRAS) com mecanismo de adaptação fuzzy, a fim de se diminuir a sensibilidade aos parâmetros da máquina. O desempenho da estratégia de controle de velocidade sensorless proposta é testada em simulações com diferentes condições de operação buscando reproduzir alguns dos problemas encontrados em aplicações práticas, utilizando o software Matlab. Os resultados obtidos foram condizentes com resultados encontrados na literatura, comprovando o bom desempenho do sistema de controle de velocidade proposto. / This work deals with the sensorless speed control for Three-phase Induction Motor in order to improve its operation at low speed and low frequency. At first, a Direct Torque Control employing Space Vector Pulse with Modulation (SVPWM) based on Flux Observer (voltage and current model) is studied and evaluated due to its high accuracy of estimating the stator-flux at low speed. The Model Adaptive Reference (MRAS) with Fuzzy Controler is chosen in order to estimate the rotor speed. This choice is based on its capability of high performance during Three-phase Induction Motor operation even if the machines parameters and the load change during the operation. At last, some simulations with diferent operational conditions at low speed are carried out in order to test the sensorless control. The results show a good perfomance and agreed with the results shown in recent papers.
236

Acurácia da ressonância magnética na detecção de roturas e de instabilidade na porção intra-articular do tendão da cabeça longa do bíceps braquial em pacientes submetidos a reparo do manguito rotador / Accuracy of magnetic resonance imaging in the detection of tears and instability in the intra-articular portion of the long head of biceps tendon in patients undergoing rotator cuff repair

Baptista, Eduardo 05 February 2019 (has links)
A literatura a respeito da capacidade da ressonância magnética em avaliar as afecções do tendão da cabeça longa do bíceps é escassa, a despeito da importância destas condições na gênese da dor e da disfunção do ombro. O objetivo primário deste estudo foi analisar o desempenho diagnóstico da ressonância magnética na detecção de roturas e de instabilidade na porção intra-articular deste tendão, comparando os achados de imagem com os dados de cirurgia artroscópica (padrão de referência). Foram objetivos secundários determinar as reprodutibilidades intraobservador e interobservador, avaliar a capacidade da ressonância magnética em classificar os tipos de rotura, avaliar a acurácia da associação entre alterações tendíneas e roturas do manguito rotador na instabilidade, além de pesquisar fatores preditores da acurácia da ressonância magnética. Foi realizado estudo transversal, com segmentos retrospectivo e prospectivo. Os critérios de inclusão foram indicação de cirurgia artroscópica do ombro para reparo do manguito rotador e exame de ressonância magnética préoperatória. Os critérios de exclusão foram: manipulação cirúrgica pregressa no ombro estudado; exames com imagens de má qualidade; intervalo entre exame pré-operatório e procedimento cirúrgico superior a um ano; indicação de técnica cirúrgica por via aberta. Foram estudados 100 ombros de 98 pacientes, operados consecutivamente de abril de 2013 a março de 2017 (47 meses). Todos os pacientes realizaram ressonância magnética de 1,5 Tesla em nossa instituição, sem utilização de contraste intra-articular. Todas as cirurgias foram realizadas pelos mesmos 3 cirurgiões, com 10 a 12 anos de experiência em cirurgia do ombro e cotovelo. Dois radiologistas, com 4 e 8 anos de experiência na área musculoesquelética, avaliaram as imagens de todos os exames, de forma independente e sem conhecimento prévio dos resultados intra-operatórios. Os mesmos casos foram revistos por um dos radiologistas, 4 meses após a primeira análise. Nossos resultados demostraram desempenho diagnóstico moderado da ressonância magnética para detecção de roturas do bíceps, com sensibilidades entre 71,1% a 73,3%, especificidades de 72,7% e acurácia entre 72 e 73%. A reprodutibilidade interobservador foi substancial (coeficiente Kappa de 0,62 a 0,69) e a reprodutibilidade intraobservador foi substancial ou quase perfeita na avaliação das roturas (coeficiente Kappa de 0,74 a 0,82). Houve correlação moderada entre os métodos para classificar o tipo de rotura (coeficiente Kappa de 0,38 a 0,47). Quando consideradas roturas completas, foram calculadas especificidades entre 75,0% e 95,7%, porém sensibilidades de 55,6% a 66,7%. Para o diagnóstico de instabilidade, observa-se sensibilidade de 52,4% a 59,1%, especificidade de 70,5% a 84% e acurácia de 64,4% a 69,5%. A avaliação combinada do deslocamento tendíneo e das roturas do manguito rotador resultou em sensibilidades de 17,5% a 47,7% e especificidades de 72,7% a 90,7%. A reprodutibilidade interobservador foi substancial (coeficiente Kappa de 0,59 a 0,7) e a reprodutibilidade intraobservador foi substancial ou quase perfeita (coeficiente Kappa de 0,76 a 0,80) para avaliação de instabilidade. Não identificamos fatores preditores para acurácia da ressonância magnética na pesquisa dessas afecções / There is paucity of literature regarding the performance of magnetic resonance imaging to assess long head of the biceps tendon disorders, despite the importance of such disorders in the genesis of pain and shoulder dysfunction. The primary objective of this study was to analyze the diagnostic performance of magnetic resonance imaging in the detection of tears and instability of the intra-articular portion of this tendon, comparing imaging findings with data from arthroscopic surgery (reference standard). Secondary objectives were to determine intraobserver and interobserver reproducibility; to evaluate the capability of MRI to classify types of tears; to evaluate the accuracy of the association between tendon displacement and rotator cuff tears to predict instability; to investigate predictive factors of magnetic resonance accuracy. A cross-sectional study was carried out, with retrospective and prospective segments. Inclusion criteria were indication of arthroscopic shoulder surgery for rotator cuff repair and preoperative magnetic resonance imaging. Exclusion criteria were: previous surgical manipulation in the studied shoulder; poor quality images; interval between preoperative examination and surgical procedure above one year; and indication of open surgical technique. We studied 100 shoulders of 98 consecutively operated patients from April 2013 to March 2017 (47 months). All patients underwent magnetic resonance imaging at our institution, using a 1.5 Tesla scanner, without use of intra-articular contrast. All surgeries were performed by the same 3 surgeons, with 10 to 12 years of experience in shoulder and elbow surgery. Two radiologists, with 4 and 8 years of experience in musculoskeletal radiology, evaluated the images independently and without previous knowledge of the intraoperative results. The same cases were reviewed by one of the radiologists, 4 months after the first analysis. Our results demonstrated a moderate diagnostic performance of MRI to detect biceps tears, with sensitivities between 71.1% and 73.3%, specificities of 72.7% and accuracy between 72 and 73%. Interobserver reproducibility was substantial (Kappa coefficient ranged from 0.62 to 0.69), and intraobserver reproducibility was substantial or almost perfect (Kappa coefficient ranged from 0.74 to 0.82). There was moderate correlation between the methods when classifying the type of tear (Kappa coefficient ranged from 0.38 to 0.47). Regarding full-thickness tears, specificities were calculated between 75.0% and 95.7%, but sensitivities from 55.6% to 66.7%. For the diagnosis of instability, sensitivity was from 52.4% to 59.1%, specificity was from 70.5% to 84% and accuracy was from 64,4% to 69,5%. The combined evaluation of tendon displacement and rotator cuff tears resulted in sensitivities from 17.5% to 47.7% and specificities from 72.7% to 90.7%. Interobserver reproducibility was substantial (Kappa coefficient ranged from 0.59 to 0.7), and intraobserver reproducibility was substantial or almost perfect (Kappa coefficient ranged from 0.76 to 0.80) for instability assessment. We did not identify predictive factors for magnetic resonance imaging accuracy in the assessment of these conditions
237

Observation et commande des procédés de digestion anaérobie pour l'amélioration de la production de biogaz / Observation and Control of Anaerobic Digestion Processes for Improved Biogas Production

Chaib Draa, Khadidja 07 July 2017 (has links)
La digestion anaérobie est un procédé permettant de transformer les déchets organiques en énergie utile, telle que le biogaz. Ce procédé fait intervenir des organismes vivants dont le comportement spécifique est fortement non linéaire. Par ailleurs, il est connu pour être sensible aux perturbations et naturellement instable. Ainsi, le développement de méthodologies efficaces pour sa commande et sa supervision est essentiel afin d’obtenir des résultats satisfaisants. Par conséquent, l’objet de cette thèse porte sur la modélisation de ce système complexe, la synthèse d’observateurs et de lois de commande afin d’améliorer le fonctionnement du procédé dans les stations de biogaz. Une modélisation formelle du procédé est alors proposée où des degrés de liberté additionnels ont été introduits dans la commande de production de biogaz. En effet, deux entrées de commande supplémentaires viennent compléter le modèle standard AM2 (Acidogenèse Methanogenesis, 2 étapes), reflétant l’ajout de substrats stimulants (acides et alcalinité) qui améliorent la qualité et la quantité du biogaz. Par la suite, l’identification des paramètres du modèle non linéaire résultant est traitée, ainsi que l’analyse de la positivité et la bornitude des variables d’état. Sur la base du modèle mathématique dérivé et des résultats de l’analyse, différents observateurs sont alors étudiés afin de surmonter le manque de capteurs fiables, autonomes et bons marché. En effet, deux observateurs sont alors développés, le premier dit invariant et le second non linéaire de la même forme que l’observateur généralisé d’Arcak. En outre, dans le but de rendre la conception d’observateurs plus robuste aux perturbations, le critère H∞ est introduit dans la synthèse. Une extension de la méthodologie est proposée pour les systèmes discrets ainsi qu’aux systèmes non linéaires avec sorties non linéaires. Pour la synthèse des différents observateurs, le théorème des accroissements finis est appliqué, ce qui permet de transformer la dynamique non linéaire de l’erreur d’estimation en un système linéaire à paramètres variants. La condition de Lipschitz est alors conjointement utilisée avec la fonction classique de Lyapunov pour la synthèse des conditions de stabilité sous forme d’Inégalités Matricielles Linéaires (LMIs). Enfin, afin d’améliorer la faisabilité de ces dernières conditions, une reformulation judicieuse de l’inégalité de Young est alors introduite. Concernant la commande du procédé, une commande par retour d’état pour le suivi d’une trajectoire de référence est choisie. Prenant en compte la disponibilité partielle des mesures du vecteur d’état, un observateur exponentiel non linéaire est introduit dans la synthèse de la loi de commande. Ainsi, une commande par retour d’état basée observateur est obtenue. Pour effectuer l’analyse de stabilité du système en boucle fermée composée du procédé, de l’observateur et du contrôleur, le lemme de Barbalat est alors utilisé conjointement avec les techniques déjà mentionnées pour la synthèse d’observateurs. Enfin, deux différentes méthodes pour le calcul des paramètres du contrôleur et de l’observateur sont proposées. Séparément, dans un premier temps. Puis simultanément dans un second temps / In this thesis, we propose a formal modelling framework for the anaerobic digestion process, where we add more degrees of freedom in the control of biogas production. Indeed, we add two additional control inputs to the standardized AM2 (Acidogenesis Methanogenesis, 2 steps) model, reflecting addition of stimulating substrates which enhance the biogas quality and quantity. Then, we describe how the parameters of the resulted nonlinear model can be identified, and we analyse the positiveness and boundedness of its state variables. Based on the derived mathematical model and the analysis results, we design different software sensors to overcome the lack of reliable and cheap sensors. Indeed, we present a general class of systems to which the considered process model belongs. Then, we design an LMI-based invariant like observer as well as an LMI-based nonlinear observer of the same form as the generalized Arcak’s observer. Furthermore, with the aim to render the observer design more robust to disturbances, we include the H∞ criterion in its synthesis. Also, to promote the use of the proposed observers in real applications, we extend the methodology to the discrete time case and to the case of nonlinear systems with nonlinear outputs. For the different observers design, we use the differential mean value theorem which allows the transformation of the nonlinear estimation error to a linear parameter varying system. Then, we use the Lipschitz conditions and the Lyapunov standard function to synthesize the stability conditions in the form of linear matrix inequalities. Finally, we enhance the feasibility of the later conditions by using a judicious reformulation of the Young’s inequality. In the thesis, we also deal with the process control where we propose a control strategy to track an admissible reference trajectory planned by the plant operator. Moreover, to account for the partial availability of the state vector measurements, we include an exponential nonlinear observer in the control synthesis. Thus, we design an observer based tracking control scheme. To perform the stability analysis of the closed loop system, composed of the system, the observer and the controller, we use the Barbalat’s lemma conjointly with the techniques already mentioned for the observers design. Finally, we propose two different methods to compute the controller and the observer parameters. In the first one, we propose to compute them separately. While, in the second one we compute the parameters simultaneously
238

Estimation de l’état interne d’une batterie lithium-ion à l’aide d’un modèle électrochimique / State estimation of a lithium-ion battery based on an electrochemical model

Blondel, Pierre 10 January 2019 (has links)
En 30 ans, les batteries Li-ion ont littéralement colonisé notre environnement depuis et leur déploiement s’accélère. Puissante, efficace, légère et compacte, cette technologie présente des problèmes de sécurité. C’est pourquoi la plupart de ces batteries sont équipées de systèmes de gestion. Ils nécessitent l’accès à certains états internes qui ne sont pas tous mesurables. Cette thèse se propose d’estimer les variables en question à l’aide d’observateurs non-linéaires. Un observateur permet d’estimer des états inaccessibles à la mesure, à partir des mesures disponibles et d’un modèle mathématique des dynamiques mises en jeu. Les transports électrochimiques à l’œuvre dans les batteries sont responsables de leur comportement. Nous en proposons un modèle électrochimique adapté à l’observation. Celui-ci repose sur la discrétisation spatiale des équations aux dérivées partielles décrivant ces phénomènes et sur une série d’hypothèses. Présenté comme un système sous forme de représentation d’état, les dynamiques sont affines et l’équation de sortie est non-linéaire. Parmi les observateurs de systèmes à sortie non-linéaire dont nous avons connaissance, aucun ne peut s’appliquer directement au modèle proposé. Nous en avons donc développé de nouveaux dont la stabilité est garantie lorsqu’une inégalité matricielle est satisfaite. Nous avons ensuite confronté ces observateurs à des données expérimentales d’éléments commercialisés. Le comportement de l’observateur est encourageant et semble être un bon compromis entre sens physique et complexité numérique / Developed in the nineties, lithium batteries have colonized our environment in less than thirty years and they keep spreading faster and faster. Powerful, efficient, light and compact, this technology remains hazardous. In order to limit the danger and slow the aging of lithium cells, most of such batteries embed a management system. The latter needs to access some internal states, which are not directly measurable. This thesis intends to estimate these variables using a nonlinear observer, which is based on an electrochemical model. The behavior of the battery is driven by the transportation phenomenon of its main electrochemical species. We therefore built a finite dimensional electrochemical model of these adapted to estimation. It relies on the spatial discretization of the partial differential equations, which describe these transportation phenomena. It also formulates some assumptions, such as the fact that an electrode globally behaves like a single particle of its active material. The obtained state space model has affine dynamics and a nonlinear output. Among the existing observers for such systems that we are aware of, none can be applied directly to the developed model. Hence, we developed new ones whose stability is guaranteed provided a linear matrix inequality holds, which is used to construct the observation gain. We then confront these observers to experimental data acquired on commercialized batteries. The obtained results are encouraging and the observer seems to be a fair compromise between physical meaning and numerical complexity
239

Etude spatiale des données collectées à bord des navires de pêche : en quoi est-elle pertinente pour la gestion des rejets de la pêche ? / Spatial analysis of on-board observer programme data : how is it relevant to the management of discards?

Pointin, Fabien 05 November 2018 (has links)
Depuis 2002, les pays membres de l’Union Européenne (UE) collectent, gèrent et fournissent des données nécessaires à la gestion des pêches et des rejets en particulier. Dans ce contexte, les programmes d’observation à la mer collectent des données à bord des navires de pêche sur la composition et la quantité des captures, y compris des rejets. En s’appuyant sur ces données, cette thèse a pour but d’analyser les variabilités spatio-temporelles des débarquements et des rejets de la pêche afin de contribuer à leur gestion. Pour cela, une méthode de cartographie basée sur des grilles à mailles variables a été développée. Cette méthode a été conçue pour produire des cartes pluriannuelles, annuelles et trimestrielles des débarquements et des rejets par espèce ou groupe selon le métier de pêche.Une plateforme basée sur des technologies Big Data a ensuite été utilisée avec pour objectifs d’affiner et d’automatiser la méthode de cartographie. Grâce à un système de stockage en ligne et un système d’analyse à haute performance, un grand nombre de cartes a ainsi pu être produit automatiquement par métier en regroupant ou non les années, les trimestres et les espèces. Finalement, l’utilité des cartes produites pour la gestion des rejets a été démontrée, en particulier dans le cadre de l’Obligation de Débarquement (Règlement (UE) n° 1380/2013). En s’appuyant sur des données de coûts et de revenus de flottilles, ces cartes permettent d’envisager des stratégies d’évitement de zones et/ou périodes de pêche propices aux captures non-désirées minimisant l’impact sur les performances économi / Since 2002, the European Union (EU) Members States collect, manage and supply data forthe management of fisheries and specifically of discards. In this context, at-sea observer programmes collect data on-board fishing vessels on the composition and quantity of catch, including discards. Based on these data, this study aims to analyse the spatio-temporal distribution of landings and discards so as to contribute to their management. In doing so, amapping method based on nested grids has been developed. This method has been designed to produce pluriannual, annual and quarterly maps of landings and discards per species or group of species according to the fishing metier.A platform based on Big Data technologies has then been used with the objectives of refining and automating the mapping method. Using an online storage system and a high-performance computing system, a large number of maps were produced automatically per métier, grouping or not years, quarters and species. Finally, the usefulness of the produced maps for managing discards has been demonstrated, particularly regarding the Landing Obligation (Regulation (UE) n° 1380/2013). Based on fleet cost and revenue data, these maps open up possibilities for identifying fishing zones and/or periods to be avoided (i.e., high bycatch) while minimising the impacts on fleet’s economic performances.
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Distinção entre os tipos 1 e 2 de tireotoxicose associada à amiodarona por meio de dúplex-Doppler colorido / Differentiation between types 1 and 2 of amiodarone-associated thyrotoxicosis using color duplex sonography

Tulio Augusto Alves Macedo 10 November 2006 (has links)
INTRODUÇÃO: A amiodarona pode causar tireotoxicose, principalmente em áreas geográficas onde a ingestão de iodo é insuficiente. Dois tipos distintos de tireotoxicose associada à amiodarona (TAA) podem ser encontrados: A) o tipo 1 - a doença é secundária à sobrecarga de iodo (fenômeno Jod-Basedow), geralmente encontrada em indivíduos com doença tireóidea preexistente, B) o tipo 2 - quando a tireotoxicose deve-se a uma tireoidite destrutiva, com ruptura folicular e liberação do conteúdo folicular. A distinção entre os dois tipos é fundamental para a conduta terapêutica. Este estudo transversal, realizado no Instituto de Radiologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo entre janeiro de 2004 a março de 2006, objetivou: A) Demonstrar a utilidade da densidade de pixéis coloridos (DPC), parâmetro objetivo obtido por meio de programa de computador, na distinção entre os dois tipos de TAA. B) Determinar os melhores critérios objetivos de distinção entre os dois tipos de TAA por meio da ultra-sonografia dúplex-Doppler colorido da tireóide. C) Conhecer o grau de concordância intra-observadores e interobservadores dos padrões subjetivos de vascularização do parênquima tireóideo. MÉTODOS: Foram examinadas 158 glândulas tireóideas por meio de dúplex-Doppler colorido. Após passagem pelos critérios de seleção, 137 indivíduos foram divididos em quatro grupos: Grupo N (n = 84), grupo A (n = 30), grupo I (n = 14) e grupo II (n = 9), compostos por indivíduos normais, eutireóideos em uso de amiodarona, pacientes com tireotoxicose tipos 1 e 2, respectivamente. Todos os indivíduos foram submetidos ao estudo dúplex-Doppler colorido da tireóide e testes laboratoriais. Os pacientes em tireotoxicose também realizaram captação de iodo radioativo em 24 horas. RESULTADOS: No grupo I, tanto a densidade de pixéis coloridos (DPC = 17,22 ± 20,81%) quanto as velocidades de pico sistólico nas artérias tireóideas superiores (VSTS = 38,54 ± 18,62 cm/s) e inferiores (VSTI = 35,35 ± 18,08 cm/s) foram maiores do que nos demais grupos (p < 0,05). As análises de concordância do padrão subjetivo de vascularização do parênquima tireóideo mostraram coeficientes kappa ponderado (kw) variando de 0,78 a 0,79 para intra-observadores e de 0,83 a 0,86 para interobservadores. CONCLUSÕES: A) A DPC tem, isoladamente, boa capacidade para distinguir os dois tipos de TAA. B) Os melhores critérios objetivos na distinção entre TAA tipos 1 e 2 são a DPC e as velocidades de pico sistólico nas artérias tireóideas. C) As análises subjetivas dos padrões de vascularização apresentam boa concordância tanto intra-observadores quanto interobservadores. / INTRODUCTION: Amiodarone can cause thyrotoxicosis, mainly in geographic insufficient iodine intake areas. Two different types of amiodarone-associated thyrotoxicosis can be found: A) type 1 - it occurs in patients with preexistent thyroid disease, such as goiter or autonomous nodule, and the iodine load associated with amiodarone triggers increased synthesis of thyroid hormones (Jod-Basedow fenomenon), B) type 2 - a destructive thyroiditis is found, characterized by follicular rupture and release of its content. In order to treat appropriately, the differentiation between the two types is crucial. This transversal study, carried through at the Institute of Radiology, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo from January 2004 to March 2006, aimed to: A) demonstrate the utility of the color pixel density (CPD), a semiquantitative parameter gotten by means of computer program, in the differentiation between the two types of AAT, B) verify the best objective criteria of distinction between the two types of AAT through the duplex-Doppler sonography of the thyroid, C) investigate the agreement intra and interobservers of the subjective classification of the thyroid vascularization. METHODS: thyroid glands of 158 subjects were examined by means of duplex-Doppler sonography. After all the selection criteria, 137 individuals were selected into four groups; group N (n = 84), group A (n = 30), group I (n = 14) and II (n = 9), compounded of normal individuals, euthyroids in use of amiodarone, and patients with thyrotoxicosis types 1 and 2, respectively. All the individuals were submitted to perform the duplex-Doppler sonography of the thyroid and laboratorial tests. Also, the patients with thyrotoxicosis had also carried through 24 hour radioactive iodine uptake. RESULTS: In the group I, not only the color pixel density (CPD = 17.22 ± 20.81%) but also the values of systolic peak velocity in the superior and the inferior thyroid arteries (SPVS = 38.54 ± 18.62 cm/s and SPVI = 35.35 ± 18.08 cm/s) were greater than in the other groups (p < 0.05). The subjective agreement analysis of the vascularization patterns showed kappa weighted (kw) coefficients varying between 0.78 and 0.79 for intra-observer, and 0.83 and 0.86 for interobserver analyses. CONCLUSIONS: A) CPD is separately able to distinguish the two types of AAT. B) The best objective criteria in the distinction between AAT types 1 and 2 are the color pixel density CPD and the peak systolic velocity in the thyroid arteries. C) The subjective analyses of the vascularization pattern show good and very good intraobserver and interobserver agreements.

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