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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.
21

Versatilité et infaisabilité : vers la fin des théories computationnelles du comportement moteur / Versatility and intractability : towards the end of computational theories of motor behavior

Flament Fultot, Martin 08 November 2019 (has links)
Le comportement moteur est un phénomène où les différentes composantes d’un système biologique sont organisées de façon à assurer la coordination d’un mouvement intentionnel. Selon les théories computationnelles, le comportement est défini comme un problème moteur dont la solution peut être trouvée par des systèmes divisés de manière hiérarchique. Les composantes traitent et communiquent entre elles de l’information représentant les aspects pertinents du problème moteur (positions, trajectoires, vitesses, forces, etc.) lesquels sont censés être organisés à leur tour selon une hiérarchie d’abstraction et de complexité ascendante. Le défi est de faire face à quatre problèmes centraux du comportement : a) Le nombre élevé de degrés de liberté et d’interactions ; b) La redondance des degrés de liberté ; c) L’anticipation des effets du mouvement ; d) L’incertitude dans l’information. Les théories computationnelles classiques proposent des schémas explicatifs composés d’un agencement de différents modèles internes (prospectifs et inverses). Plus récemment, l’approche bayésienne propose un schéma hiérarchique plus homogène lequel est censé faire face aussi à l’incertitude de l’information. Cette recherche démontre que les théories computationnelles, y compris l’approche bayésienne, sont paralysées par un dilemme insurmontable : soit elles peuvent passer à l’échelle de manière computationnellement faisable - les calculs peuvent être réalisés en un temps raisonnable - mais dans ce cas elles ne peuvent pas reproduire la versatilité caractéristique du comportement des êtres vivants ; soit elles aspirent à reproduire la versatilité biologique mais alors elles sont infaisables. / Motor behavior is a phenomenon where the components making up a biological system are organized so as to ensure the coordination of a purposeful movement. According to computational theories, behavior is defined as a motor problem the solution of which can be found by systems divided hierarchically. The components process and communicate information representing the relevant variables of the motor problem (positions, trajectories, velocities, forces, etc.) which are, in turn, assumed to be organized as a hierarchy of increasing abstraction and complexity. The challenge is to tackle the four core problems of behavior: a) The high number of degrees of freedom and their interactions; b) The redundancy of degrees of freedom; c) The anticipation of the effects of movement; d) The uncertainty in information. Classical computational theories advance explanatory schemas made of structured sets of internal models (forward and inverse). More recently, the Bayesian approach advances a more homogeneous hierarchical schema which is supposed to account for uncertainty in information. This research shows that computational theories, including the Bayesian approach, are crippled by an unsolvable dilemma: The first horn is that if the models can scale up while staying computationally tractable, i.e. the computations can be carried out in a reasonable amount of time, then they fail to reproduce the versatility which characterizes the behavior of living beings. The second horn is that if the models aspire to reproduce biological versatility, then they are intractable.
22

Automatic Control Strategies of Mean Arterial Pressure and Cardiac Output. MIMO controllers, PID, internal model control, adaptive model reference, and neural nets are developed to regulate mean arterial pressure and cardiac output using the drugs sodium Nitroprusside and dopamine

Enbiya, Saleh A. January 2013 (has links)
High blood pressure, also called hypertension is one of the most common worldwide diseases afflicting humans and is a major risk factor for stroke, myocardial infarction, vascular disease, and chronic kidney disease. If blood pressure is controlled and oscillations in the hemodynamic variables are reduced, patients experience fewer complications after surgery. In clinical practice, this is usually achieved using manual drug delivery. Given that different patients have different sensitivity and reaction time to drugs, determining manually the right drug infusion rates may be difficult. This is a problem where automatic drug delivery can provide a solution, especially if it is designed to adapt to variations in the patient’s conditions. This research work presents an investigation into the development of abnormal blood pressure (hypertension) controllers for postoperative patients. Control of the drugs infusion rates is used to simultaneously regulate the hemodynamic variables such as the Mean Arterial Pressure (MAP) and the Cardiac Output (CO) at the desired level. The implementation of optimal control system is very essential to improve the quality of patient care and also to reduce the workload of healthcare staff and costs. Many researchers have conducted studies earlier on modelling and/or control of abnormal blood pressure for postoperative patients. However, there are still many concerns about smooth transition of blood pressure without any side effect. The blood pressure is classified in two categories: high blood pressure (Hypertension) and low blood pressure (Hypotension). The hypertension often occurred after cardiac surgery, and the hypotension occurred during cardiac surgery. To achieve the optimal control solution for these abnormal blood pressures, many methods are proposed, one of the common methods is infusing the drug related to blood pressure to maintain it at the desired level. There are several kinds of vasodilating drugs such as Sodium Nitroprusside (SNP), Dopamine (DPM), Nitro-glycerine (NTG), and so on, which can be used to treat postoperative patients, also used for hypertensive emergencies to keep the blood pressure at safety level. A comparative performance of two types of algorithms has been presented in chapter four. These include the Internal Model Control (IMC), and Proportional-Integral-Derivative (PID) controller. The resulting controllers are implemented, tested and verified for three sensitivity patient response. SNP is used for all three patients’ situation in order to reduce the pressure smoothly and maintain it at the desire level. A Genetic Algorithms (GAs) optimization technique has been implemented to optimise the controllers’ parameters. A set of experiments are presented to demonstrate the merits and capabilities of the control algorithms. The simulation results in chapter four have demonstrated that the performance criteria are satisfied with the IMC, and PID controllers. On the other hand, the settling time for the PID control of all three patients’ response is shorter than the settling time with IMC controller. Using multiple interacting drugs to control both the MAP and CO of patients with different sensitivity to drugs is a challenging task. A Multivariable Model Reference Adaptive Control (MMRAC) algorithm is developed using a two-input, two-output patient model. Because of the difference in patient’s sensitivity to the drug, and in order to cover the wide ranges of patients, Model Reference Adaptive Control (MRAC) has been implemented to obtain the optimal infusion rates of DPM and SNP. This is developed in chapters five and six. Computer simulations were carried out to investigate the performance of this controller. The results show that the proposed adaptive scheme is robust with respect to disturbances and variations in model parameters, the simulation results have demonstrated that this algorithm cannot cover the wide range of patient’s sensitivity to drugs, due to that shortcoming, a PID controller using a Neural Network that tunes the controller parameters was designed and implemented. The parameters of the PID controller were optimised offline using Matlab genetic algorithm. The proposed Neuro-PID controller has been tested and validated to demonstrate its merits and capabilities compared to the existing approaches to cover wide range of patients. / Libyan Ministry of Higher Education scholarship
23

Rôle de la vision pour le contrôle de la dynamique du mouvement lors d'un geste de pointage manuel chez l'adulte ainsi que chez l'enfant

Mackrous, Isabelle January 2009 (has links)
Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.
24

Optimisation des performances de réseaux de capteurs dynamiques par le contrôle de synchronisation dans les systèmes ultra large bande / Optimizing the performance of dynamic sensor networks by controlling the synchronization in ultra wide band systems

Alhakim, Rshdee 29 January 2013 (has links)
Dans cette thèse nous nous sommes principalement concentrés sur les transmissions impulsion radio Ultra Large Bande (UWB-IR) qui a plusieurs avantages grâce à la nature de sa bande très large (entre 3.1GHZ et 10.6GHz) qui permet un débit élevé et une très bonne résolution temporelle. Ainsi, la très courte durée des impulsions émises assure une transmission robuste dans un canal multi-trajets dense. Enfin la faible densité spectrale de puissance du signal permet au système UWB de coexister avec les applications existantes. En raison de toutes ces caractéristiques, la technologie UWB a été considérée comme une technologie prometteuse pour les applications WSN. Cependant, il existe plusieurs défis technologiques pour l'implémentation des systèmes UWB. A savoir, une distorsion différente de la forme d'onde du signal reçu pour chaque trajet, la conception d'antennes très larges bandes de petites dimensions et non coûteuses, la synchronisation d'un signal impulsionnel, l'utilisation de modulation d'onde d'ordre élevé pour améliorer le débit etc. Dans ce travail, Nous allons nous intéresser à l'étude et l'amélioration de la synchronisation temporelle dans les systèmes ULB. / The basic concept of Impulse-Radio UWB (IR-UWB) technology is to transmit and receive baseband impulse waveform streams of very low power density and ultra-short duration pulses (typically at nanosecond scale). These properties of UWB give rise to fine time-domain resolution, rich multipath diversity, low power and low cost on-chip implementation facility, high secure and safety, enhanced penetration capability, high user capacity, and potential spectrum compatibility with existing narrowband systems. Due to all these features, UWB technology has been considered as a feasible technology for WSN applications. While UWB has many reasons to make it a useful and exciting technology for wireless sensor networks and many other applications, it also has some challenges which must be overcome for it to become a popular approach, such as interference from other UWB users, accurate modelling of the UWB channel in various environments, wideband RF component (antennas, low noise amplifiers) designs, accurate synchronization, high sampling rate for digital implementations, and so on. In this thesis, we will focus only on one of the most critical issues in ultra wideband systems: Timing Synchronization.
25

Observateurs et régulation de sortie robuste pour des systèmes non linéaires / Observers and robust output regulation for nonlinear systems

Astolfi, Daniele 27 May 2016 (has links)
Les observateurs et la régulation de sortie sont deux thèmes centraux de la théorie des système non linéaires. Bien que de nombreux chercheurs ont consacré leur attention à ces questions depuis plus de trente ans, il y a encore de nombreuses questions ouvertes. Dans la théorie des observateurs un rôle clé est joué par les observateurs à grand gain. Le but de la première partie de la thèse est d'etudier nouvelles techniques qui permettent de surmonter ou au moins d'atténuer les principaux problèmes qui caractérisent cette classe d'observateurs. Nous proposons une nouvelle classe d'observateurs à grand gain, appelé "low-power", qui permet de surmonter les problèmes numériques, d'éviter le phénomène de peaking et d'améliorer les propriétés de sensibilité aux bruit de mesure à haute fréquence. La deuxième partie de la thèse aborde du problème de la régulation de sortie, qui a été résolu pour les systèmes linéaires au cours des années 70, par Francis et Wonham qui ont énoncé le célèbre «principe de modèle interne". Des solutions constructives ont aussi été proposées dans le cadre non linéaire mais sous des hypothèses restrictives qui réduisent la classe des systèmes auxquels cette méthodologie peut être appliquée. Dans la thèse, nous nous concentrons sur le problème de la régulation de sortie en présence de perturbations périodiques, et nous proposons une nouvelle approche qui nous permet de considérer une classe plus large de systèmes non linéaires. La technique obtenué est robuste au sens défini par Francis et Wonham. / Observers and output regulation are two central topics in nonlinear control system theory. Although many researchers have devoted their attention to these issues for more than 30 years, there are still many open questions. In the observer theory a key role is played by the so called high-gain observers. The purpose of the first part of the thesis is to study novel techniques which allow to overcome or at least to mitigate some of the main drawbacks characterizing this class of observers. We propose a novel class of high-gain observers, denoted as ``low-power'', which allows to overcome numerical problems, to avoid the peaking phenomenon and to improve the sensitivity properties to high-frequency measurement noise. The second part of the thesis addresses the output regulation problem, solved for linear systems during the 70's by Francis and Wonham who coined the celebrated ``internal model principle''. Constructive solutions have also been proposed in the nonlinear framework but under restrictive assumptions that reduce the class of systems to which this methodology can be applied. In this thesis we focus on the output regulation problem in presence of periodic disturbances and we propose a novel approach which allows to consider a broader class of nonlinear systems. The resulting design is robust in the sense defined by Francis and Wonham.
26

Rôle de la vision pour le contrôle de la dynamique du mouvement lors d'un geste de pointage manuel chez l'adulte ainsi que chez l'enfant

Mackrous, Isabelle January 2009 (has links)
Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal
27

Otimização meta heurística e controle baseado no modelo interno aplicados em sistemas de geração fotovoltaica conectados à rede elétrica monofásica

Chaves, Eric Nery 18 November 2016 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho apresenta o estudo, desenvolvimento e aplicação de novas técnicas de controle aos sistemas de geração de energia fotovoltaica, conectados à rede elétrica monofásica, visando a melhoria da eficiência destes sistemas em relação aos métodos de controle tipicamente utilizados. O trabalho é dividido em duas partes principais, as quais estão relacionadas ao rastreamento do ponto de máxima potência (Maximum Power Point Tracking – MPPT) e, depois, ao controlador interno dos conversores boost-quadrático – lado dos painéis fotovoltaicos – assim como aos controladores do inversor de tensão, no lado da rede elétrica monofásica. A primeira parte do trabalho consiste no desenvolvimento de um algoritmo de meta heurística para o MPPT, o qual é baseado no método do recozimento simulado (Simulated Annealing - SA) e tem como objetivo a determinação do ponto de máximo global, buscando soluções fora de uma vizinhança próxima, de modo a evitar o atracamento em máximos locais da curva de potência de saída do arranjo de painéis fotovoltaicos, melhorando, assim, o aproveitamento da energia em situações de sombreamento parcial. A segunda parte do trabalho apresenta o projeto de controladores baseados no modelo interno (Internal Model Control – IMC) com 1 grau de liberdade (1 Degree of Freedom – 1 DOF) aplicados, primeiramente, ao conversor CC-CC Boost Quadrático, utilizado para o MPPT, e, posteriormente, a um inversor de tensão com filtro LCL, conectado à rede elétrica monofásica, operando no modo de injeção de corrente. É apresentada a modelagem matemática de ambos os conversores e analisada a compensação da realimentação interna ao sistema do inversor de tensão, correspondente ao desacoplamento da tensão da rede, através da estratégia de alimentação à frente (Feedforward). Visando-se uma base de comparação, para a análise de desempenho do conversor IMC – 1DOF, também é aplicado ao sistema de injeção de corrente, o controlador Proporcional-Ressonante (P+Res). São apresentados resultados de simulação computacional e experimentais de ambos os 8 controladores, os quais permitem verificar o desempenho do sistema em situação de rede fraca e carga local não-linear. / This paper presents the study, development and application of new control techniques for photovoltaic power generation systems, connected to single-phase power grid in order to improve the efficiency of these systems in relation to control methods typically used. The work is divided into two main parts, which are related to tracking the maximum power point (Maximum Power Point Tracking - MPPT) and then the internal controller of boost quadratic converters - side of the photovoltaic panels - as well as the controllers the voltage inverter, the side of the single-phase mains. The first part of the work is the development of a heuristic goal algorithm for MPPT, which is based on the method of simulated annealing (Simulated Annealing - SA) and aims at determining the overall maximum point, seeking out solutions in a close vicinity, so as to prevent the docking local maxima in the curve of power output of the photovoltaic array, thereby improving the utilization of energy in partial shading situations. The second part presents the design of controllers based on internal model (Internal Model Control - IMC) with 1 degree of freedom (1 Degree of Freedom - 1 DOF) applied, first, the DC-DC Boost Quadratic converter, used for MPPT, and thereafter, a voltage inverter with LCL filter connected to the single phase power supply operating in current injection mode. A mathematical modeling of both converters and analyzed the compensation of internal feedback to the voltage inverter system corresponding to the disconnection of the mains voltage through the power strategy a head (feedforward). A basis of comparison for the performance analysis of IMC-1DOF converter is aiming at, is also applied to the current injection system, Proportional-Resonant Controller (P + Res). They are presented computer simulation and experimental results of both controllers, which allow you to check the system performance in low and non-linear local load network situation. / Tese (Doutorado)
28

Controladores baseados no princípio do modelo interno com ação Anti-Windup / Controllers basead on internal model principle with anti-windup

Soares, Claudio Eduardo 28 April 2011 (has links)
Made available in DSpace on 2016-12-12T17:38:37Z (GMT). No. of bitstreams: 1 CLAUDIO EDUARDO SOARES.pdf: 20046362 bytes, checksum: 135e6d7d3a6f98bef9152afe645904c4 (MD5) Previous issue date: 2011-04-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The controllers based on the internal model principle have found emphasis on control systems due to its ability to perform robust tracking of signals whose generator models are embedded in their internal structures. Controllers with integral, resonant and repetitive terms are examples of this principle. However, the control systems are subject to physical limitations that restrict their operation under certain conditions. The amplitude saturation of the control action is the most common type of restriction found in real systems. The impacts of the saturation of control action are known as windup and its consequences for systems with integral action have already been exhaustive examined. However, the impacts of saturation of control action are not restricted to this type of controller. Other controllers based on the internal model principle are also affected by the windup phenomenon due to saturation of the action control. The impacts of the windup phenomenon for resonant, multi-resonant and repetitive controllers are investigated in this dissertation and an anti-windup technique is suggested to mitigate the impacts of the control saturation on these controllers. The proposed anti-windup technique is based on the conditional integration technique, originally developed for the controllers with integral action, and it is named conditional update. Simulation results are presented to validate the proposed technique. / Os controladores baseados no princípio do modelo interno têm encontrado destaque no controle de sistemas devido a sua capacidade de realizar o rastreamento robusto dos sinais cujos modelos geradores estejam embutidos nas suas estruturas internas. Os controladores com ação integral, ressonantes e repetitivos são exemplos da aplicação deste princípio. Contudo, os sistemas de controle estão sujeitos a limitações físicas que restringem suas condições de operação. A saturação da amplitude da ação de controle é o tipo de limitação mais comum encontrada nos sistemas reais. Os impactos da saturação da ação de controle são conhecidos como windup e suas consequências para os sistemas com ação integral já foram exaustivamente analisadas. Porém, os impactos da saturação da ação de controle não se restringem a este tipo de controlador. Outros controladores baseados no princípio do modelo interno também são afetados pelo fenômeno windup decorrente da saturação da ação de controle. Os impactos do fenômeno windup sobre os controladores ressonantes, multiressonantes e repetitivos são investigados nesta dissertação e uma técnica anti-windup é sugerida para atenuar os impactos da saturação da ação de controle sobre estes controladores. A técnica anti-windup proposta é baseada na técnica da integração condicional, originalmente desenvolvida para os controladores com ação integral e, por isso, denominada de atualização condicional. Resultados de simulação são apresentados para validação da técnica proposta.
29

Karel Teige, Jan Mukařovský a Bohuslav Brouk jako teoretikové surrealismu / Karel Teige, Jan Mukařovský and Bohuslav Brouk as Theorists of Surrealism

Kuchařová, Markéta January 2016 (has links)
The content of the thesis is the surrealistic object and its reflection among the czech theorists. The first part of the thesis describes the problematic of surrealistic object and subject-objective relations in surrealism. Breton's philosophical approach is introduced, as well as his concept of object's crisis. The first part also outlines the meaning of found object, concept of convulsive beauty and Dali's paranoic-critical method as a source of surrealistic imagery. The second part of the thesis is focused on the reflection of surrealistic object presentation and on relations between arts and reality according to the concepts of Jan Mukařovský. The third part of the thesis is dedicated to conceptualization of aesthetics of Bohuslav Brouk in the light of surrealism. In this part the scope of Brouk's understanding of subject-objective relations is briefly described, as well his interpretation of surrealistic object.The last part of the thesis outlines the Teige's conception of surrealistic work in the terms of the sources of surrealistic imagination.
30

[en] MODEL FOR CALCULATING THE NEED FOR CAPITAL TO COVER THE UNDERWRITING RISKS OF NON-LIFE OPERATIONS / [pt] MODELO DE CÁLCULO DA NECESSIDADE DE CAPITAL PARA COBRIR OS RISCOS DE SUBSCRIÇÃO DE OPERAÇÕES NÃO VIDA

EDUARDO HENRIQUE ALTIERI 03 May 2019 (has links)
[pt] Importante questão que se coloca atualmente é a capacidade de medição do volume de capital necessário, às sociedades seguradoras, para fazer frente aos diversos tipos de risco que tais companhias suportam no exercício de suas atividades. Esse volume de capital necessário deve ser tal que permita à companhia suportar variabilidades no negócio. As motivações para o desenvolvimento de modelos matemáticos visando à determinação desta necessidade de capital são tanto a preocupação das próprias companhias com a sua gestão de risco, como também aspectos relacionados ao estabelecimento de requerimentos de capital exigidos pelo regulador de seguro às sociedades seguradoras para fazer frente aos riscos suportados. Entre tais riscos, encontra-se a categoria dos riscos de subscrição, relacionados diretamente à operação central de uma seguradora (design de produto, precificação, processo de aceitação, regulação de sinistros e provisionamento). Esta dissertação apresenta uma proposta de modelo para determinação do volume necessário de capital para fazer frente aos riscos de subscrição, na qual tal categoria de riscos é segregada nos riscos de provisão de sinistros (relativos aos sinistros ocorridos e, assim, relacionados às provisões de sinistros) e nos riscos de emissão/precificação (relativos aos sinistros à ocorrer num horizonte de tempo de 1 ano, considerando novos negócios). Em especial, o modelo proposto utiliza processos de simulação que levam em consideração a estrutura de dependência das variáveis envolvidas e linhas de negócio, fazendo uso do conceito de cópulas condicionais. / [en] Important question that arises today is the ability to measure the amount of capital necessary to insurance companies, to cope with various types of risk that these companies support in performing their activities. This volume of capital required must be such as to enable the company to bear variability in business. The motivations for the development of mathematical models aimed at the determination of those capital needs are both the concern of companies with their own risk management, as well as aspects related to establishing capital requirements required by the insurance regulator to insurance companies to face the risks borne. Among such risks, is the category of underwriting risks, directly related to the core operation of an insurance company (product design, pricing, underwriting process, loss settlement and provisioning). This dissertation proposes a model for determining the appropriate amount of capital to cope with the underwriting risks, where such risk category is segregated in reserving risks (relative to incurred events) and pricing risks (relative to events occurring in the time horizon of 1 year, considering new businesses). In particular, the proposed model uses simulation processes that take into account the dependence structure of the variables involved and lines of business, making use of the concept of conditional copulas.

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