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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

Un Camino Puraficativo: Negación Sanjuanina y Desengaño en <i>El Pastor de Nochebuena</i> de Juan de Palafox y Mendoza

Espericueta, José Gabriel 24 April 2003 (has links)
No description available.
22

The Sin of Omission: The United States and South Africa in the Nixon Years

Morgan, Eric J. 25 June 2003 (has links)
No description available.
23

Fault Lines

Schnelle, Robert C., Jr. 11 October 2001 (has links)
No description available.
24

Wretched, Ambiguous, Abject: Ordinary Ways of Being in Selected Works by Alex la Guma, Bessie Head, and J.M Coetzee

Drbal, Susanna 10 October 2005 (has links)
No description available.
25

Serving women and the state: the league of women in Communist Poland

Nowak, Barbara Agnieszka 29 September 2004 (has links)
No description available.
26

Imagining Henry VIII: Cultural Memory and the Tudor King, 1535-1625

Rankin, Mark 10 July 2007 (has links)
No description available.
27

Projeto de controladores PID com índice de desempenho H&#8734; com mitigação seletiva de harmônicos / Design of PID controllers with H&#8734; performance index and for selective harmonic mitigation

Magossi, Rafael Fernando Quirino 28 January 2019 (has links)
Os controladores Proporcional+Integral+Derivativo (PID) são largamente empregados na indústria devido à sua estrutura contendo ações integral e derivativa e por possuir ordem fixa. Na literatura, encontram-se vários métodos para a sua sintonia. Nesse trabalho é apresentada uma forma de obter a sintonia do PID utilizando o índice de desempenho H&#8734; de forma não-iterativa. Essa sintonia é feita utilizando-se a representação em espaço de estado na forma canônica controlável. No entanto, como trata-se de um controlador de ordem fixa, variações na planta podem interferir de forma significativa no desempenho desejado e precisam ser compensadas. Assim, propõe-se também uma adaptação dos parâmetros do PID de modo a manter a função de transferência de malha fechada o mais próximo possível da nominal utilizada na sintonia. Para isso, modela-se a estrutura de controle como um sistema linear sobre-determinado com restrições lineares, advindos de conjuntos estabilizantes baseados no conceito de assinatura Hurwitz, e utiliza-se um método de otimização quadrática para obter os parâmetros do controlador. Para circunvir o conservadorismo da norma H&#8734;, um método para mitigar apenas o efeito de algumas harmônicas na saída do sistema também é proposto, restringindo-se a sensibilidade do sistema que é representada por elipses no lugar geométrico dos ganhos estabilizantes do PID. Simulações no software Matlab, Simulink e PSIM foram utilizadas para validar os modelos e metodologias propostas. Resultados experimentais demonstraram a eficácia do método para mitigação de harmônicos em um conversor CC&#8211;CC do tipo boost. / Proportional + integral + derivative (PID) controllers are widely used in the industry due to their structure containing integral and derivative actions and for having a fixed order. In the literature, there are several methods for PID tuning. In this work it is presented a way to obtain PID tuning using a non-iterative H&#8734; design. This tuning is done using the state-space representation in the controllable canonical form. However, because it is a fixed-order controller, plant variations can significantly interfere with the desired performance and need to be compensated. Thus, it is also proposed to adapt the PID parameters so as to keep the closed-loop transfer function as close as possible to the nominal used in the tuning. For this, the control structure is modeled as an over-determined linear system with linear constraints, derived from stabilizing sets based on the Hurwitz signature concept, and a quadratic optimization method is used to obtain the controller parameters. In order to circumvent the conservatism of the norm H&#8734;, a method to mitigate only the effect of selected harmonics on the output of the system is also proposed, constraining the sensitivity function of the system which is represented by ellipses in the stabilizing gains locus of the PID. Simulations in Matlab, Simulink and PSIM softwares were used to validate the proposed models and methodologies. Experimental results demonstrated the effectiveness of the harmonic mitigation method in a boost DC&#8211;DC converter.
28

Adaptive-passive and active control of vibration and wave propagation in cylindrical shells using smart materials

Xu, Mubing 23 September 2005 (has links)
No description available.
29

FIELD TEST AND ANALYSIS OF TWO PRESTRESSED CONCRETE BRIDGES AFTER DECK REPLACEMENT WITH FRP PANELS

KANTHA SAMY, MADHAN KUMAR 09 October 2007 (has links)
No description available.
30

Stochastic Material Characterization of Heterogeneous Media with Randomly Distributed Material Properties

Shang, Shen 11 December 2012 (has links)
No description available.

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