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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.
41

Análise do impacto da comunicação via rede FlexRay em sistemas de controle

Michelin, Thiago José January 2014 (has links)
A importância das redes de comunicação industriais em modernos sistemas de automação e controle industriais tem aumentado significativamente nos últimos anos, devido aos avanços nas áreas de processadores e softwares embarcados, que permitem o desenvolvimento de dispositivos com elevada capacidade de processamento a custos reduzidos. Estas características também são muito importantes em sistemas automotivos, visto que existe uma tendência para a substituição de sistemas mecânicos e hidráulicos em veículos e o espaço disponível para implementação é bastante reduzido. Esta substituição passa pela elaboração de complexos algoritmos de controle, os quais, quando operam sobre uma rede de comunicação, precisam considerar explicitamente os efeitos do canal de comunicação compartilhado na dinâmica do sistema em malha fechada. Este trabalho apresenta uma análise do impacto da comunicação em rede sobre sistemas de controle. Mais especificamente, analisa-se o comportamento do protocolo Flexray, recentemente desenvolvido por um consórcio de importantes empresas e que incorpora interessantes conceitos para escalonamento de mensagens síncronas e assíncronas. No trabalho foram realizados experimentos com três diferentes tipos de controladores aplicados ao estudo de caso de uma suspensão ativa, onde o sistema tem sua malha fechada sobre a rede FlexRay. / The importance of communication networks on modern automation systems has increased significantly over the last years, mostly due to advances in embedded microprocessor and software technologies, which enable the development of devices with high processing power at reduced costs. These characteristics are very important for vehicle systems, since there is nowadays a trend to replace mechanical and hydraulic systems, and the space available for implementation is limited. This replacement requires very complex control algorithms, which, when operating on a communication network, have to consider explicitly the effects introduced by the shared communication channel on the closed loop system dynamics. This work presents an analysis of the network communication impact over control systems. More specifically, it is of interest to analyse the behavior of the FlexRay protocol, which has been recently developed by a Consortium of important companies and incorporates interesting concepts of synchronous and asynchronous message scheduling. In this work, some experiments were performed with three controllers, which were developed using different methodologies, applied to the case study of an active suspension system, where the loop is closed over the FlexRay protocol.
42

Formulation de capsules à cœur aqueux pour la délivrance stimulable de protéines / Formulation of aqueous core capsules for the triggered release of proteins

Brun, Geoffrey 18 December 2015 (has links)
Les gradients de concentration de peptides ou de protéines, ou leur relargage localisé, jouent un rôle primordial dans les voies de communication inter-cellulaire. L'activation locale de cellules est étudiée in vitro à l'aide de sources artificielles contraignantes ou invasives de protéines (pipettes, dispositifs microfluidiques). Des méthodes plus douces et moins invasives sont très demandées. À cet effet, nous avons développé deux types de capsules capables de libérer des macromolécules sous l'effet d'une stimulation extérieure. Le premier système emploie des liposomes additionnés d'un amphiphile à azobenzène, tensioactif ou polyélectrolyte, capable de générer des pores à travers la membrane sous l'effet de la lumière. Les temps de dissolution des assemblages lipides/tensioactifs et les cinétiques de relargage (perméabilité) sous irradiation lumineuse ont été étudiées par diffusion dynamique de la lumière et fluorescence. Le second système repose sur des capsules à cœur aqueux et à coque polymère, formées par polyaddition interfaciale. Nous avons montré que l'inclusion de chaînes thermosensibles dans la membrane (polyNIPAM, par ex.) rendait la stabilité de la capsule dépendante de la température. Nous avons démontré sur des capsules millimétriques, chargées avec du dextrane ou des protéines, que cela permettait le contrôle du relargage. L'utilisation de polymère à UCST en milieu aqueux nous a permis d'obtenir les premières capsules thermosensibles capables de libérer leur contenu par élévation de la température au dessus d'une valeur critique. Cela ouvre une voie prometteuse au développement d'un système biocompatible de libération de protéines. / Concentration gradients and local delivery of peptides or proteins play a crucial role in intercellular communication. In vitro, the effects of local activation of cells are studied with constrained or invasive artificial protein sources (pipettes, microfluidics). Milder and remotely-triggered techniques for the release of encapsulated biomolecules are highly in demand. To this aim we developed two classes of capsules able to release macromolecules upon an external stimulation. The first system is based on liposomes sensitized with azobenzene-containing amphiphiles (surfactants or polyelectrolytes) that can open pores in the membrane upon exposure to light. The dissolution time of lipids/surfactants assemblies and rate of release (permeability) under light irradiation has been assessed by dynamic light scattering and fluorescence measurements. The second system is a model of capsules with an aqueous core and a polymer shell, formed by interfacial polyaddition. We showed that inclusion of temperature-responsive chains in the membrane, e.g. polyNIPAM, confers temperature-dependant stability to the capsules; we demonstrated with millimeter-sized capsules loaded with dextran or proteins that this can be used to trigger the release. Using chains with UCST in water, we obtained the first temperature-sensitive capsules able to release their content upon increasing the temperature above a threshold. This represents a promising route to the biocompatible delivery of proteins.
43

A study of particle structure and film formation mechanism on the mechanical properties of synthetic rubber films

Tungchaiwattana, Somjit January 2014 (has links)
This thesis investigated a new group of poly(Bd)/poly(Bd-co-MAA) core-shell particles that were ionically crosslinked and cast as nanostructured ionomer films from aqueous dispersions. The new group of poly(Bd)/poly(Bd-co-MAA) core-shell particles were studied for structure-property relationships and morphology. The covalent crosslinking content in the core and the shell were varied at constant ionic crosslinking. Stress-strain data showed control of the nanostructured films. The chain transfer agent used during the preparation of the nanoparticles core-shells was shown to independently tune the mechanical properties of the films.
44

Emotionally triggered involuntary violent behaviour not attributed to a mental disorder : conceptual criteria and their reliability

Joubert, Pierre M. January 2015 (has links)
Emotionally triggered involuntary violent behaviour not attributed to a mental disorder: conceptual criteria and their reliability. This study conceptualised emotionally triggered involuntary violent behaviour (ETIVB), developed criteria for the identification of ETIVB, and examined their validity and reliability. South Africa criminal courts allow for a defence called “non-pathological criminal incapacity”. It refers inter alia to extreme emotional arousal triggering involuntary violent behaviour. This is usually called an “emotional storm” or a so-called “psychological blow automatism”. Psychiatrists are often called to give expert testimony in this regard, but there is no conceptual clarity or criteria upon which to base it. This difficulty is compounded by the requirement set by the criminal courts that the behaviour may not be attributed to a mental disorder (in this thesis the terms mental disorder and mental illness are used interchangeably). The first advance in obtaining clarity was afforded by focusing on the behaviour as distinct from 1) legal and jurisprudential considerations as well as 2) whether the behaviour is (not) attributed to mental disorder. The subsequent research questions driving the study were, “what counts as ETIVB?” In particular, what counts respectively as „emotional triggered‟, „involuntary‟, „violent‟, and „behaviour‟. Through conceptual methods suggested in the work of J.L. Austin, draft ETIVB-criteria were developed and then repetitively applied to a set of 28 cases. Twenty seven of these cases involved a charge of murder. The other one had behaved violently, but was not charged. The criteria were refined and their content validity derived by a repetitive to-and-fro process between comparative exploration of the concepts and their empirical application to the set of cases. The criteria were formulated into an instrument by which a psychiatrist can identify ETIVB. In addition provision was made to record whether ETIVB is, or is not, attributed to specific causes including mental disorder, but only as an attribution that follows after ETIVB has been identified. The ETIVB-instrument was subjected to reliability testing among 14 psychiatrists and 10 psychiatrists in training. They applied the ETIVB-criteria to a set of 5 externally validated case summaries. The participants had first been trained in the use of the instrument by considering other example cases. Statistical analyses of inter-rater reliability were performed. The modified kappa agreement ranged from 0.388 (fair) to 0.636 (substantial) across study cases for all criteria A.1 – H.1. The criteria for violence had exceptionally high inter-rater agreement, all being 0.947 and higher. The complexity of the ETIVB-construct transpired when inter-rater reliability analyses were compared between cases in that different cases posed different challenges for inter-rater agreement. The reliability testing across cases however, showed which less agreed-upon items would benefit from refinement. / Thesis (PhD)--University of Pretoria, 2015. / gm2015 / Psychiatry / PhD / Unrestricted
45

Adaptive learning and robust model predictive control for uncertain dynamic systems

Zhang, Kunwu 07 January 2022 (has links)
Recent decades have witnessed the phenomenal success of model predictive control (MPC) in a wide spectrum of domains, such as process industries, intelligent transportation, automotive applications, power systems, cyber security, and robotics. For constrained dynamic systems subject to uncertainties, robust MPC is attractive due to its capability of effectively dealing with various types of uncertainties while ensuring optimal performance concerning prescribed performance indices. But most robust MPC schemes require prior knowledge on the uncertainty, which may not be satisfied in practical applications. Therefore, it is desired to design robust MPC algorithms that proactively update the uncertainty description based on the history of inputs and measurements, motivating the development of adaptive MPC. This dissertation investigates four problems in robust and adaptive MPC from theoretical and application points of view. New algorithms are developed to address these issues efficiently with theoretical guarantees of closed-loop performance. Chapter 1 provides an overview of robust MPC, adaptive MPC, and self-triggered MPC, where the recent advances in these fields are reviewed. Chapter 2 presents notations and preliminary results that are used in this dissertation. Chapter 3 investigates adaptive MPC for a class of constrained linear systems with unknown model parameters. Based on the recursive least-squares (RLS) technique, we design an online set-membership system identification scheme to estimate unknown parameters. Then a novel integration of the proposed estimator and homothetic tube MPC is developed to improve closed-loop performance and reduce conservatism. In Chapter 4, a self-triggered adaptive MPC method is proposed for constrained discrete-time nonlinear systems subject to parametric uncertainties and additive disturbances. Based on the zonotope-based reachable set computation, a set-membership parameter estimator is developed to refine a set-valued description of the time-varying parametric uncertainty under the self-triggered scheduling. We leverage this estimation scheme to design a novel self-triggered adaptive MPC approach for uncertain nonlinear systems. The resultant adaptive MPC method can reduce the average sampling frequency further while preserving comparable closed-loop performance compared with the periodic adaptive MPC method. Chapter 5 proposes a robust nonlinear MPC scheme for the visual servoing of quadrotors subject to external disturbances. By using the virtual camera approach, an image-based visual servoing (IBVS) system model is established with decoupled image kinematics and quadrotor dynamics. A robust MPC scheme is developed to maintain the visual target stay within the field of view of the camera, where the tightened state constraints are constructed based on the Lipschitz condition to tackle external disturbances. In Chapter 6, an adaptive MPC scheme is proposed for the trajectory tracking of perturbed autonomous ground vehicles (AGVs) subject to input constraints. We develop an RLS-based set-membership based parameter to improve the prediction accuracy. In the proposed adaptive MPC scheme, a robustness constraint is designed to handle parametric and additive uncertainties. The proposed constraint has the offline computed shape and online updated shrinkage rate, leading to further reduced conservatism and slightly increased computational complexity compared with the robust MPC methods. Chapter 7 shows some conclusion remarks and future research directions. / Graduate
46

Biophysical Approaches for the Multi-System Analysis of Neural Control of Movement and Neurologic Rehabilitation

Hulbert, Sarah Marie, HULBERT January 2018 (has links)
No description available.
47

NEW METHODS FOR DETECTING EARTHQUAKE SWARMS AND TRANSIENT MOTION TO CHARACTERIZE HOW FAULTS SLIP

Holtkamp, Stephen Gregg 05 June 2013 (has links)
No description available.
48

Study on Whistler-mode Triggered Emissions in the Magnetosphere / 磁気圏におけるホイッスラーモード・トリガード放射の研究

Nogi, Takeshi 23 March 2023 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第24618号 / 工博第5124号 / 新制||工||1979(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 大村 善治, 教授 松尾 哲司, 教授 小嶋 浩嗣 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
49

Spontaneous Calcium Oscillations During Diastole in the Whole Heart: The Influence of Ryanodine Reception Function and Gap Junction Coupling

Plummer, Bradley N. January 2010 (has links)
No description available.
50

UV-Triggered and Thermo-Induced Crosslinking of Polymers Containing 1-Functionalized Benzocyclobutenes

Xing, Liwen January 2017 (has links)
No description available.

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