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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.
521

Impact sur l'intelligibilité dans les troubles de la production de la parole pathologique

Woisard, Virginie 14 June 2011 (has links)
L’intelligibilité de la parole est un véritable enjeu dans la prise en charge des personnes présentant un trouble de la production de la parole pathologique (TPPP). L’usage de ce terme, avec un sens commun recouvrant le domaine de la compréhension, et un sens restreint répondant à la mesure du transfert d’information linguistique dans un contexte de test, entretient une ambigüité ; ambigüité qui entrave le développement des concepts de prise en charge. L’objectif de ce travail de thèse est, à travers trois groupes d’expériences autour de la notion d’intelligibilité, de proposer un cadre conceptuel pouvant servir à organiser la prise en charge des TPPP et à identifier les questions de recherche fondamentale impliquées dans la problématique de l’intelligibilité dans les TPPP.L’objectif principal du premier groupe d’expériences est d’étudier la place de l’intelligibilité dans les stratégies cognitives sous-jacentes à la perception de la parole pathologique. La méthode utilisée est une catégorisation libre..La deuxième série d’expériences est consacrée à la manière dont un groupe d’experts réalise une tâche de jugement de sévérité comparée à une tâche de jugement d’intelligibilité. Le troisième groupe d’expériences cherche à déterminer les cibles les plus efficaces dans la prise en charge des TPPP. Elle repose sur l’hypothèse suivante : la conservation d’une perception juste d’un phonème ou d’une syllabe malgré sa distorsion pathologique permet de déterminer sa contribution à l’intelligibilité et participe à la définition de la notion de robustesse perceptive. Pour tester cette hypothèse, une méthode d’analyse du taux de perception obtenu par un jury d’auditeurs, en fonction du degré de vraisemblance issu d’un système automatique de reconnaissance a été formalisée. Les résultats de ces expériences, interprétées sous l’éclairage croisé des théories sur la perception et de la production de la parole et des modèles de santé, nous ont permis de proposer une définition des différents concepts dans la perspective de la classification internationale du fonctionnement. / The intelligibility of speech is a real challenge for the management of speech disorders. The use of this word, with a common meaning of comprehension and, a specific meaning in a context of test, of measurement of the information transfer, carries some ambiguity, which could hinder the concept of management.The purpose of this work is to propose a conceptual framework for the management of pathological speech production (PSP) through three kinds of experiments. The aim of the first set of experiments is to study the place of the intelligibility within the underlying cognitive strategies of the perception of pathological speech.A free classification method is used with a corpus of sentences read by 33 speakers: 20 patients with speech disorders (a pathological speech production due to neurological diseases or sequellae of cancer or malformative lesions) and 13 normal subjects. The second set of experiments studies the way an expert group performs evaluation of severity compared to evaluation of intelligibility. During an off line experiment, the corpus of the previous study filled by a corpus of different sentences by speaker, was presented to 5 judges (logopedists and phoniatriciansThe third group of experiments looks for the most efficient targets for managing speech disorders. It‘s based on the following assumption: the preservation of a correct perception of a phoneme or a syllable, despite its pathological distortion, allows to determine its contribution to intelligibility and participates to the notion of perceptive robustness. For testing this assumption, was proposed a method of analysis by the identification score (obtained by a jury of listeners) function of the degree of” plausibility (obtained by an automatic system for speech recognition). The outcome of these experiments, adopting the points of view of some perception theories of SD mixed with health models allow us to precise the definition of the main concepts in the prospect of the international classification of functioning.
522

Power electronic systems design co-ordination for doubly-fed induction generator wind turbines

Ozakturk, Meliksah January 2012 (has links)
Wind turbine modelling using doubly-fed induction generators is a well-known subject. However, studies have tended to focus on optimising the components of the system rather than considering the interaction between the components. This research examines the interaction of the control methods for a doubly-fed induction generator (DFIG) in a wind turbine application integrating them with the crowbar protection control and DC-link brake control to make the best use of the converter. The controls of the rotor-side and the grid-side converters of the DFIG model are both well established and have been shown to work. Typically the crowbar protection is designed in order to protect the rotor-side converter and the power electronic components of the DFIG system from high currents occurring in the rotor due to the faults. The DC-link brake-overvoltage protection is also designed to prevent the overcharging of the DC-link capacitor placed between the rotor-side converter and the grid-side converter. In order to show that these protection schemes work and with thought can co-ordinate with each other, tests consisting of a number of balanced three-, two- and one-phase voltage sags are applied to the network voltage. The main contributions of this thesis are establishing operational tuning and design limits for the controllers and system subassemblies. This is to minimise the electrical subsystem interaction while maintaining adequate performance, and have an improved DC-link control. This work also includes a full electrical system study of the wind turbine and an essential literature review on significant references in the field of the DFIG wind turbine system modelling, control and protection. Specifically this research project makes a number of novel contributions to the literature: enhanced DC voltage control including operating point sensitivity analysis and dynamic stiffness assessment, sensitivity and robustness analyses of the power loop control and control loop segmentation by appropriately tuning the controller loops.
523

Robustness in fire of steel framed structures with realistic connections

Chen, Lu January 2013 (has links)
Joints are the most critical elements in a steel framed structure. In most design guides or codes, the joints are assumed to a have higher fire resistance than the connected structural members because of the lower temperatures in the joints. However, in severe fire conditions, a connected beam's temperature may be higher than its limiting temperature and the beam may develop catenary action when the beam’s axial shortening from large deflections becomes greater than the beam’s thermal expansion. This beam catenary action force could fracture the joints, increasing the risk of progressive collapse. This research focuses on the interaction between joints and the connected steel beams and columns in steel framed structures in fire, including how the behaviour of a joint-beam assembly may be efficiently analyzed and how the joints may be constructed to achieve high degrees of catenary action. Three methods of simulating the joint behaviour in fire have been developed and implemented in the commercial finite element software ABAQUS. In the first modelling method, all structural members, including the connections, were simulated using detailed solid elements to enable detailed behaviour of the structure to be faithfully represented. In the second method, the columns were represented by conventional line (beam) elements, the joints were represented using springs (Connector Elements) based on the component based method, and the beam was modelled using solid elements. In the third method, the joints were modelled using springs as in the second method and the beam and columns were simulated using line (beam) elements. As expected, the detailed simulation method was extremely time-consuming, but was able to produce detailed and accurate results. The simulation results from the second and third methods contained some inaccuracies, but depending on the simulation objective, their simulation results may be acceptable. In particular, the third simulation method was very efficient, suitable for simulating complete frame structures under very large deflections in fire. The first method (detailed finite element method) was then used to investigate how to change the joint details to increase the survivability of restrained steel beams and beam-column assemblies at high temperatures since it enables detailed behaviour of the structure to be faithfully represented. It is found that by improving joint deformation capacity, in particular, using extended endplate connection with fire resistant bolts, very high temperatures can be resisted. The frame robustness in fire was investigated using the third simulation method to save computation time. The simulation structure was three-bay by three-floor and different scenarios of fire location, fire spread and initial structural damage were considered. The simulation results show that once failure of a column occurs, progressive collapse of the structure could be easily triggered and it would be rather futile to only enhance the joint capacity. Therefore, in addition to the measures of improving joint capacities (both rotation and strength), design of the affected columns should include consideration of the additional catenary forces from the connected beams and the increased effective lengths. Furthermore, the lateral bracing system should be ensured to provide the structure with lateral restraint.
524

Um sistema de rastreamento de olhar tolerante a movimentações da face / A tracking system to look tolerant movements of the face

Flávio Luiz Coutinho 05 May 2006 (has links)
A crescente capacidade do poder computacional e a proliferação de dispositivos ao nosso redor vem permitindo o desenvolvimento de novas e sofisticadas interfaces para interação humano-computador que reagem à presença e ao estado de seus usuários. Como o olhar tem a capacidade de transmitir muitas informações sobre o usuário, rastreadores de olhar, dispositivos que estimam a direção para onde uma pessoa olha, tem papel importante no desenvolvimento de tais interfaces. Entre suas aplicações temos o auxílio a pessoas com dificuldades motoras, que podem utilizar um rastreador de olhar como substituto ao mouse, aplicações de diagnóstico, que estudam evidências do comportamento humano, ou ainda o desenvolvimento de interfaces que utilizem a informação sobre o olhar como um canal a mais de comunicação com o usuário para perceber suas intenções. Muitas técnicas para atingir tal objetivo foram desenvolvidas mas as tradicionais ainda oferecem certas dificuldades de uso para seus usuários como a intolerância a movimentos de cabeça e a necessidade de calibração por sessão de uso. Neste trabalho fizemos um levantamento de uma série de técnicas de rastreamento de olhar, indo das mais tradicionais até algumas mais recentes que visam melhorar a facilidade de uso destes sistemas. Uma das técnicas mais promissoras utiliza múltiplas fontes de luz fixadas nos cantos do monitor do computador. Através da análise da posição dos reflexos gerados por essas fontes de luz sobre a córnea, juntamente com a informação da posição da pupila, presentes em imagens capturadas do olho, é possível estimar o ponto observado no monitor. Devido às suas vantagens ela foi escolhida para estudo mais detalhado e implementação. Extensos testes utilizando simulações foram realizados para avaliar seu desempenho. Foi também desenvolvida uma extensão dessa técnica, utilizando um modelo mais preciso do olho, visando melhorar sua precisão. Ao final apresentamos nossa implementação, baseada nessa extensão da técnica original, que é tolerante a movimentação da face e mostramos os resultados obtidos em testes realizados com um grupo de usuários. / Recent advances in computing power and the proliferation of computing devices around us allowed the development of new computer interfaces which can react to the presence and state of its users. Since gaze can transmit a lot of information about the user, gaze trackers, devices that can estimate the direction which a person is looking at, have an important role in the development of such interfaces. Among gaze tracking applications, we have aid for people with limited motor skills, human behavior studies, and the development of interfaces that can take gaze information as an additional communication channel with the user. Lots of techniques have been developed to reach this goal, but they have some problems that make them hard to be widely used. These problems are the need of calibration for each use session and the need to keep the user\'s head still. In this work we studied some of the existing gaze tracking techniques, from the more traditional ones to more recent ones. One of the most interesting techniques makes use of multiple light sources fixed at the monitor\'s corners. By analyzing the positions of corneal reflections and the pupil present in captured images of the eye, it is possible to estimate the gaze point on the monitor screen. Due to its advantages this technique was chosen for a deeper study and implementation. Lots of experiments using simulated data have been carried out to validate the technique. Using a more accurate model of the eye, an extension for this technique was also developed to increase its precision. Finally, we present our implementation, that allows for large head movement, as well as test results obtained from real users.
525

Dual-user haptic training system / Dual-utilisateurs systèmes haptiques de formation

Liu, Fei 22 September 2016 (has links)
Dans le secteur médical tout particulièrement, la qualité du geste est primordiale et les professionnels doivent être formés par la pratique pour acquérir un niveau de compétences compatible avec l'exercice de leur métier. Depuis une dizaine d'année, les simulateurs informatiques aident les apprenants dans de nombreux apprentissages mais ils doivent encore être associés à des travaux pratiques sur mannequins, animaux ou cadavres, qui pourtant n'offrent pas toujours suffisamment de réalisme par rapport aux vrais patients, et sont coûteux à l'usage. Aussi, leur formation s'achève généralement sur de vrais patients, ce qui présente des risques. Les simulateurs haptiques (fournissant une sensation d'effort) deviennent aujourd'hui une solution plus appropriée car ils peuvent reproduire des efforts résistant réalistes et proposer une infinité de cas d'étude pré-enregistrés. Cependant, apprendre seul sur un simulateur n'est pas toujours aussi efficace qu'un apprentissage "à quatre mains" (celles de l'instructeur et de l'apprenant manipulant les mêmes outils en coopération). Cette étude propose donc un système haptique de formation pratique à deux utilisateurs : l'instructeur et l'apprenant, interagissant chacun à travers leur propre interface haptique. Ils collaborent ainsi, avec des outils et un environnement de travail soit réels (l'outil est manipulé par un robot) soit virtuels. Une approche énergétique, faisant appel notamment à la modélisation par port-Hamiltonien, a été utilisée pour garantir la stabilité et la robustesse du système. Une étude comparative (en simulation) avec deux autres systèmes haptiques multi utilisateurs a montré l'intérêt de ce nouveau système pour la formation pratique. Il a été développé et validé expérimentalement sur des interfaces à un seul degré de liberté. Son extension à six degrés de liberté est facilitée par les choix de modélisation. Afin de pouvoir utiliser le système quand les deux protagonistes sont éloignés, cette étude propose des pistes d'amélioration qui ne sont pas encore optimisées. / More particularly in the medical field, gesture quality is primordial. Professionals have to follow hands-on trainings to acquire a sufficient level of skills in the call of duty. For a decade, computer based simulators have helped the learners in numerous learnings, but these simulations still have to be associated with hands-on trainings on manikins, animals or cadavers, even if they do not always provide a sufficient level of realism and they are costly in the long term. Therefore, their training period has to finish on real patients, which is risky. Haptic simulators (furnishing an effort feeling) are becoming a more appropriated solution as they can reproduce realist efforts applied by organs onto the tools and they can provide countless prerecorded use cases. However, learning alone on a simulator is not always efficient compared to a fellowship training (or supervised training) where the instructor and the trainee manipulate together the same tools. Thus, this study introduces an haptic system for supervised hands-on training: the instructor and the trainee interoperate through their own haptic interface. They collaborate either with a real tool dived into a real environment (the tool is handled by a robotic arm), or with a virtual tool/environment. An energetic approach, using in particular the port-Hamiltonian modeling, has been used to ensure the stability and the robustness of the system. This system has been designed and validated experimentally on a one degree of freedom haptic interface. A comparative study with two other dual-user haptic systems (in simulation) showed the interest of this new architecture for hands-on training. In order to use this system when both users are away from each other, this study proposes some enhancements to cope with constant communication time delays, but they are not optimized yet.
526

Akcelerace výpočtu stínů a osvětlení / Shadowing and Lighting Acceleration

Milet, Tomáš January 2021 (has links)
Cílem této práce je prezentovat metody pro akceleraci výpočtů stínů a osvětlení.  Práce se zabývá akcelerací na vzorek přesných stínů pomocí stínových těles na různých platformách. Obsahem práce je také zvýšení přesnosti stínových map a zvýšení přesnosti osvětlování scény s mnoha světly.
527

Klimatická změna a její vliv na vodohospodářské řešení zásobního objemu nádrže / Climate Change and Its Impact on Water Management Analysis of Reservoir Storage Capacity

Hudec, Martin January 2018 (has links)
The diploma thesis describes Climate Change and impacts of Climate Change on the development of the water management analyis of reservoir strorage capacity. The development of climate chang influence on reserviors storage capacity is presented until 2100. It also gives a detailed online downscaling description.
528

Monte Carlo simulace elektronového rozptylu v rastrovacím prozařovacím elektronovém mikroskopu / Monte Carlo simulations of electron scattering in scanning transmission electron microscopy

Záchej, Samuel January 2016 (has links)
This thesis deals with an electron scattering in STEM microscopy on objects with dif-ferent shapes, such as cuboid, sphere and hollow capsule. Monte Carlo simulations are used for description of multiple electron scattering. Except the theoretical analysis of the electron scattering and simulation methods, the thesis contains design and realiza-tion of an algorithm simulating electron scattering in given objects. In addition, there is a design for robustness evaluation of the simulation, based on comparison between results and known signals for a given object. Reliability of the algorithm was verified by experimental measurements of the electron scattering on a carbon layer.
529

Fiabilité et analyse physique des défaillances des composants électroniques sous contraintes électro-thermiques pour des applications en mécatronique. / Reliability and failure analysis of electronic devices under electro-thermal constraints for mecatronic applications

Mbarek, Safa 22 December 2017 (has links)
L’amélioration des systèmes de conversion d’énergie rend les dispositifs à base de SiC très attractifs pour leur efficacité, compacité et robustesse. Cependant, leur comportement en réponse à un défaut de court-circuit doit être soigneusement étudié pour assurer la fiabilité des systèmes. Ce travail de recherche porte sur les problèmes de robustesse et de fiabilité du MOSFET SiC sous contraintes de court-circuit. Cette étude repose sur des caractérisations électriques et microstructurales. La somme de toutes les caractérisations avant, pendant et après les tests de robustesse ainsi que l’analyse microstructurale permet de définir des hypothèses sur l’origine physique de la défaillance pour ce type de composants. De plus, la mesure de la capacité est introduite au cours des tests de vieillissement en tant qu’indicateur de santé et outil clé pour remonter à l’origine physique du défaut. / The improvement of power conversion systems makes SiC devices very attractive for efficiency, compacity and robustness. However, their behavior in response to short circuit mode must be carefulli studied to ensure the reliability of systems. This research work deals with the SiC MOSFET robustness and reliability issues under short-circuit constraints. It is based upon electrical and microstructural characterizations. The sum of all the characterizations before, during and after the robustness tests as well as microstructural analysis allow to define hypotheses regarding the physical origin of failure of such components. Also, caoacitance measurement is introduced during aging tests as a health indicator and a key tool to go back to the physical origin of the defect.
530

Etude et modélisation des dégradations des composants de puissance grand gap soumis à des contraintes thermiques et électriques / Study and modeling of large gap power components degradations subjected to thermal and electrical constraints

Jouha, Wadia 29 November 2018 (has links)
Ce travail vise à étudier la robustesse de trois générations de MOSFET SiC de puissance (Silicon Carbide Metal Oxide Semiconductor Field E_ect Transistors). Plusieurs approches sont suivies : la caractérisation électrique, la modélisation physique, les tests de vieillissement et la simulation physique. Un modèle compact basé sur une nouvelle méthode d'extraction de paramètres et sur les résultats de caractérisation électrique est présenté. Les paramètres extraits du modèle (tensionde seuil, transconductance de la région de saturation et paramètre du champ électrique transverse) sont utilisés pour analyser avec précision le comportement statique de trois générations de MOSFET SiC. La robustesse de ces dispositifs sont étudiées par deux tests : le test HTRB (High Temperature Reverse Bias) et le test ESD (Electrostatic Discharge). Une simulation physique est réalisée pour comprendre l'impact de la température et des paramètres physiques sur les caractérisations électriques des MOSFETs SiC. / This work aims to investigate the robustness of three generations of power SiC MOSFETs (SiliconCarbide Metal Oxide Semiconductor Field E_ect Transistors). Several approaches are followed :electrical characterization, device modeling, ageing tests and physical simulation. An improvedcompact model based on an accurate parameters extraction method and one electrical characterization results is presented. The parameters extracted precisely from the model (thresholdvoltage, saturation region transconductance...) are used to accurately analyze the static behaviorof two generations of SiC MOSFETs. The robustness of these devices are investigated bytwo tests : HTRB (High Temperature Reverse Bias) stress and an ESD (Electrostatic Discharge)stress. Physical simulation is conducted to understand the impact of the temperature and thephysical parameters on the device electrical characterizations.

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