Teses em Engenharia Elétrica (Doutorado) - PPGEE/UNICAMP
URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/9607
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Item Acesso aberto (Open Access) Otimização com restrições lineares e pre-condicionamento periódico: teoria e experimentos(Universidade Estadual de Campinas, 1987-09-18) GOMES, Hermínio Simões; MARTINEZ, José Mário; http://lattes.cnpq.br/8543703316798123Item Acesso aberto (Open Access) Transformada seno discreta com rotação de eixos bidimensional (DSTr -2D): aplicações na codificação e interpolação de imagens para redução de efeito de blocos(Universidade Estadual de Campinas, 1998-10-29) PELAES, Evaldo Gonçalves; IANO, Yuzo; http://lattes.cnpq.br/1819902045004845This work presents a new tool for image coding and image interpolation based on the two-dimensional discrete sine transform with axis rotation (DSTr-2D). The main characteristics of this transform are the few blocking effects found in the reconstructed image and its computational simplicity. In this work, the DSTr-2D is applied to image interpolation and its performance is compared with results obtained from DCT. A method of interpolation using DCT without extrapolation is also presented. The DSTr-2D achieves a performance better than the other interpolation methods used for comparison purposes. Indeed the better performance is obtained when the sample rate is increased. The DSTr-2D is also applied to the image coding, and it was verified that its advantage relative to DCT in terms of blocking effects in the reconstructed image. The results obtained in image coding using DSTr-2D are compared with results obtained from DCT and LOT. The images were coded using scalar, gaussian, laplacian and Lloid-Max quantization Finally, the DSTr-2D is applied to performs the image coding and the image interpolation, simultaneously.Item Acesso aberto (Open Access) Problema de autovalores, otimização de funções matriciais e robustez de sistemas dinâmicos: uma abordagem algoritmica(Universidade Estadual de Campinas, 1988) ESPIRITO SANTO, Adilson Oliveira do; YAMAKAMI, Akebo; http://lattes.cnpq.br/7091050557018479In this work we analyse three problems. In the first, we present some algorithms to solve the eigenvector and eigenvalue problems of the symmetric matrix, In lhe second we analyse the optimization problems with matricial constraints and finally in the third some robustness properties of linear continuons time dynamic systems are studied. The eigenvector and etgenvalue problems are two methods: the decomposition technique on the matrix and the optimization of the Rayleigh quotient. In the propose two algorithms based on the Newton method gradient method. To solve a class of lhe optimization problems with matricial constraints we propose a methodologie based on the cutting plane technique. Two exemples are treated. Finally, for a given linear continuons time we determine sufflcient conditlons for the existence feedback matrix such that the closed-Ioop system is sense that the pertubed system is asymptocally stable, analysed using of the system, second one we and conjugated dynamic systems of a constant robust in the sense that the perturbed system is asymptocally stable.Item Acesso aberto (Open Access) Propagação de ondas eletromagnéticas em meios com camadas múltiplas usando funções de Green diádicas e sua aplicação no modelamento de florestas(Universidade Estadual de Campinas, 1982) CAVALCANTE, Gervásio Protásio dos Santos; ROGERS, David Antony; GIAROLA, Attilio José; http://lattes.cnpq.br/7834721061998959Item Acesso aberto (Open Access) Método rigoroso das diferenças finitas em análise de estruturas de guias dielétricos anisotrópicos com perfil de índice de refração variável(Universidade Estadual de Campinas, 1992-07-13) SOUZA SOBRINHO, Carlos Leônidas da Silva; GIAROLA, Attilio José; http://lattes.cnpq.br/7834721061998959A rigorous, general and versatil finite-difference formulation for the analysis of the propagation characteristics in structures, having the dielectric waveguide as the basic element, is presented here. In this formulation, the finite-diff erence method is used in the numerical solution of the scalar wave equation, written in terms of the transverse components of the magnetic field. As a result, a conventional eigenvalue problem is obtained without the presence of spurious modes (present in previous formulations), due to the implicit inclusion of the divergence of the magnetic field equal to zero. The general case of biaxial anisotropic dielectrics is considered, with the refractive index profile varying arbitrarily in the waveguide cross section. Dispersion characteristics for isolated and parallel coupled dielectric waveguides are calculated. The theoretical development was then used to solve particular problems and the results agree with those available from other methods. Results were obtained for a variety of guiding wave structures, of much interest, particularly for the development of integrated optics.Item Acesso aberto (Open Access) Contribuição para o planejamento econômico de sistemas de energias elétrica: um algoritmo para a expansão simultânea da geração e transmissão usando aproximação linear(Universidade Estadual de Campinas, 1983) BRANCO, Tadeu da Mata Medeiros; KOO, Robert Liang; http://lattes.cnpq.br/0610628446391103Contribution tho the eletric power systems economic planning: an algorithm for the simultaneos expansion of generation and transmission using linear approximation. Economic Planning of Generation and Transmission in Electrical Power Systems constitutes a Nonlinear Optimization Problem which has some complexity and must be treated in a global manner. Several iteractive methods has been proposed to solve problems of this nature but sometimes are unaceptable due time and large computer storage requirements. This complexity is enlarged if generation and transmission were simultaneously optimized. Linear programming has been considered as a promissing tool to solve these problems but due the linearization of nonlinear functions the results presents some loss of accuracy, even so, for planning purposes these results are aceptable. In this work we propose a Global Algorithm for the Economic Planning of Simultaneous Expansion of Generation and Transmission in Electrical Power Systems based on the application of a Linear Programming Method and Minimum Cost Flow Algorithm which permits discret addition of generation and circuits units to the system with minimum investment cost in each period. Losses and maximum capacity of the lines are included in the algorithm, some examples are shown and at the end we suggest some extensions to further works.Item Acesso aberto (Open Access) Método das Diferenças Finitas no Domínio do Tempo (FDTD) aplicado a guias dielétricos controlados por plasma(Universidade Estadual de Campinas, 1996-02-09) FARIAS, Rubem Gonçalves; GIAROLA, Attilio José; http://lattes.cnpq.br/7834721061998959A finite-difference in the time domain (FDTD) formulation is developed for plasmas magnetized along an arbitrary direction and applicable to two dimensions (2D-FDTD) and to three dimensions (3D-FDTD) dielectric devices. Emphasis is given to the iterative calculation of the convolution between the electric field vector and the electric susceptibility tensor of the magnetized plasma. Various types of devices are also proposed for the propagation of signals in the millimeter-wave band. The method is applied to structures controlled by plasma. This plasma may be induced by an optical beam applied to a semiconductor layer deposited on the waveguide. In this case, the propagation characteristic of the waveguide is controlled by an optical beam with appropiate energy. This plasma may also also be introduced in the semiconductor by means of doping. For these devices the waveguide core is completely filled with plasma. With this option the propagation of the RF fields is controlled by a static magnetic field. Some devices with single and coupled waveguides are analyzed. The possibility of an effective control of phase and coupling, as well as the operating bandwidth with a single mode was examined, particularly with optically controlled waveguides. Due to the lack of data in the specialized literature, gradual discretization criteria and rigorous tests of convergence are proposed. Various types of data are used to accomplish this objective. As a result, a kind of discretization profile is obtained and is applied to the remaining devices.Item Acesso aberto (Open Access) Métodos de projeção de convergência finita para sistemas lineares e quadrados mínimos(Universidade Estadual de Campinas, 1987-03-20) GUERRA, Renato Borges; MARTÍNEZ PÉREZ, José Mário; http://lattes.cnpq.br/8543703316798123