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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.
11

Percolação direcionada em redes regulares bidimensionais. / Directed percolation on two-dimensional regular lattices.

Neves, Ubiraci Pereira da Costa 24 April 1992 (has links)
Utilizando uma técnica de matriz de transferência, expandimos em série a probabilidade de percolação P(q) para o problema da percolação por sítio na rede quadrada direcionada. Nosso método revela uma inesperada conexão entre este problema e o da enumeração dos modos de se dissecar uma bola. Mostramos que o método pode também ser usado para se expandir em série o tamanho médio do cluster S (p) . Uma análise baseada nos aproximantes de Padé fornece estimativas do valor crítico pc, e também do expoente crítico &#946. / Using a transfer matrix technique we obtain an extended series expansion of the percolation probability P(q) for the directed site percolation problem on the square lattice. Our method reveals an up to now unsuspected connection between this problem and the enumeration of the ways of dissecting a ball. We show that the method can also be used to determine a series expansion for the mean cluster size S(p). An analysis based on Padé approximants gives estimates of the critical threshold pc, and also of the critical exponent &#946.
12

Initial-boundary-value problems for the Stokes and Navier-Stokes equations on staggered grids /

Nilsson, Jonas. January 2000 (has links)
Akademisk avhandling--Institutionen för informationsteknologi--Uppsala Universitet, 2000. / Bibliogr. p. 113-118.
13

Quelques contributions sur l'approximation rationnelle et les méthodes d'extrapolation

Matos, Ana Christina Brezinski, Claude January 2007 (has links)
Reproduction de : Habilitation à diriger des recherches : Sciences mathématiques : Lille 1 : 2006. / N° d'ordre (Lille 1) : 532. Résumé. Titre provenant de la page de titre du document numérisé. Bibliogr. p. 101-107. Liste des publications.
14

Soluções solitônicas por aproximantes de Padé via método iterativo de Taylor / Solitonic solutions via Pade approximants and an iterative Taylor method

Biazotti, Herbert Antonio 28 September 2018 (has links)
Submitted by HERBERT ANTONIO BIAZOTTI (biazotti@gmail.com) on 2018-10-14T02:15:25Z No. of bitstreams: 1 Herbert Antonio Biazotti final.pdf: 1521042 bytes, checksum: 515112dfe90c1ccb1ed085960211c14a (MD5) / Rejected by Pamella Benevides Gonçalves null (pamella@feg.unesp.br), reason: Solicitamos que realize correções na submissão seguindo as orientações abaixo  As palavras-chave e keyword devem ser separadas entre si por ponto final e também finalizadas por ponto. (favor ver exemplo no template ou diretrizes)  Qualquer que seja o tipo de ilustração (figuras, desenhos, gráficos, diagramas, fluxogramas, fotografias, mapa, planta, quadro, imagem entre outros) sua identificação (título) aparece na parte superior com letra tamanho 12; o Na parte inferior, Tamanho da letra 10, indicar a fonte consultada (elemento obrigatório, mesmo que seja produção do próprio autor esta regra serve também para as tabelas), notas e outras informações necessárias à sua compreensão  Devem conter a fonte mesmo que elaborada pelo autor. o Ex: Fonte: Autor Fonte: Autoria própria o (favor ver exemplo no template ou diretrizes)  As fontes das ilustrações, tabelas e quadros não podem ser links . A referência deve ser informada ao final, seguindo os padrões da ABNT. Para indicar a fonte, deve ser colocada a autoria e o ano entre parênteses. Ex.: Martins (2010). Sobre as referências 1 VACHASPATI, T. "Kinks and Domain Walls". New York: [s.n.], 2006. (remover aspas) 2 RAJARAMAN, R. "Solitons and Instantons". North-Holland, Amsterdam: [s.n.], 1989. (remover aspas) Rever paginação de alguns periódicos, pois não há traço indicando o intervalo de páginas Mais informações acesse o link: http://www2.feg.unesp.br/Home/Biblioteca21/diretrizes-2016.pdf Agradecemos a compreensão. on 2018-10-15T14:56:30Z (GMT) / Submitted by HERBERT ANTONIO BIAZOTTI (biazotti@gmail.com) on 2018-10-16T05:43:30Z No. of bitstreams: 1 Herbert Antonio Biazotti.pdf: 1523685 bytes, checksum: 0170fcc999d5569a23643063df78c433 (MD5) / Approved for entry into archive by Pamella Benevides Gonçalves null (pamella@feg.unesp.br) on 2018-10-16T17:52:17Z (GMT) No. of bitstreams: 1 biazotti_ha_me_guara.pdf: 1523685 bytes, checksum: 0170fcc999d5569a23643063df78c433 (MD5) / Made available in DSpace on 2018-10-16T17:52:17Z (GMT). No. of bitstreams: 1 biazotti_ha_me_guara.pdf: 1523685 bytes, checksum: 0170fcc999d5569a23643063df78c433 (MD5) Previous issue date: 2018-09-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Certos sistemas físicos podem ser descritos por uma classe de equações não-lineares. Essas equações descrevem pacotes de onda chamado de sólitons que tem aplicações em diversas áreas, por exemplo, Óptica, Cosmologia, Matéria Condensada e Física de Partículas. Alguns métodos foram desenvolvidos ao longo dos anos para encontrar as soluções dessas equações. Buscaremos essas soluções usando o que chamamos de Método Iterativo de Taylor (MIT), que fornece uma solução aproximada em polinômio de Taylor de forma distinta do que se tem na literatura. Usaremos o MIT para calcular soluções por aproximantes de Padé que são razões entre dois polinômios e fornecem soluções melhores que o polinômio de Taylor que o gerou. Inicialmente resolveremos a equação de um modelo de um campo denominado λφ4 . Em seguida resolveremos um modelo com dois campos escalares acoplados e encontraremos uma solução analítica aproximada em casos onde não existe solução analítica, explorando a diversidade das soluções do modelo. Usando essa abordagem por aproximantes de Padé veremos que há algumas vantagens em relação a outros métodos. / Certain physical systems can be described by a class of non-linear differential equations. Those equations describe wave packets called solitons which have applications in several areas, for example, Optics, Cosmology, Condensed Matter, and Particle Physics. Some methods have been developed over the years to find solutions to these equations. We will look for those solutions using what we call the Taylor Iterative Method (TIM), which provides an approximate solution in terms of a Taylor’s polynomial in a unusual way, regarding the present literature. We will use TIM to calculate solutions by Padé approximants, which are ratios between two polynomials and provide better solutions than the Taylor polynomial itself. We first solve the field equation of a model called λφ4. Then we will solve a model with two coupled scalar fields and find an approximate analytic solution in cases where there is no known analytical solution, exploring the diversity of the solutions of the model. We will see that there are some advantages in using the Padè approximants as compared to other methods / 1586040
15

Percolação direcionada em redes regulares bidimensionais. / Directed percolation on two-dimensional regular lattices.

Ubiraci Pereira da Costa Neves 24 April 1992 (has links)
Utilizando uma técnica de matriz de transferência, expandimos em série a probabilidade de percolação P(q) para o problema da percolação por sítio na rede quadrada direcionada. Nosso método revela uma inesperada conexão entre este problema e o da enumeração dos modos de se dissecar uma bola. Mostramos que o método pode também ser usado para se expandir em série o tamanho médio do cluster S (p) . Uma análise baseada nos aproximantes de Padé fornece estimativas do valor crítico pc, e também do expoente crítico &#946. / Using a transfer matrix technique we obtain an extended series expansion of the percolation probability P(q) for the directed site percolation problem on the square lattice. Our method reveals an up to now unsuspected connection between this problem and the enumeration of the ways of dissecting a ball. We show that the method can also be used to determine a series expansion for the mean cluster size S(p). An analysis based on Padé approximants gives estimates of the critical threshold pc, and also of the critical exponent &#946.
16

Pade Approximants And One Of Its Applications

Fowe, Tame-kouontcho 01 January 2007 (has links)
This thesis is concerned with a brief summary of the theory of Pade approximants and one of its applications to Finance. Proofs of most of the theorems are omitted and many developments could not be mentioned due to the vastness of the field of Pade approximations. We provide reference to research papers and books that contain exhaustive treatment of the subject. This thesis is mainly divided into two parts. In the first part we derive a general expression of the Pade approximants and some of the results that will be related to the work on the second part of the thesis. The Aitken's method for quick convergence of series is highlighted as Pade[L/1] . We explore the criteria for convergence of a series approximated by Pade approximants and obtain its relationship to numerical analysis with the help of the Crank-Nicholson method. The second part shows how Pade approximants can be a smooth method to model the term structure of interest rates using stochastic processes and the no arbitrage argument. Pade approximants have been considered by physicists to be appropriate for approximating large classes of functions. This fact is used here to compare Pade approximants with very low indices and two parameters to interest rates variations provided by the Federal Reserve System in the United States.
17

Convergence et applications d'approximations rationnelles vectorielles

Le Ferrand, Hervé 29 May 1992 (has links) (PDF)
Les approximants de Padé et leurs généralisations sont depuis plusieurs années l'objet d'intenses recherches, et leurs applications sont nombreuses. Beaucoup de problèmes théoriques restent cependant en suspens: problèmes tout d'abord d'existence, d'unicité problèmes de convergence, d'accélération de convergence. L'objectif du travail présenté ici était justement d'apporter des réponses à de telles questions. Dans la première partie nous nous sommes intéressés aux approximants de Padé vectoriels de séries de matrices. Des conditions d'existence et d'unicité, des résultats de convergence sont donnés, ainsi que le lien avec la théorie de Lanczos pour la résolution de systèmes linéaires. Nous utilisons aussi les approximants de Padé vectoriels pour l'approximation simultanée d'une fonction et de sa dérivée. Dans la seconde partie une condition suffisante pour la convergence quadratique de l'epsilon algorithme topologique pour la résolution de systèmes non linéaires est donnée. Des résultats d'accélération de la convergence sont démontrés pour la deuxième colonne de l'epsilon algorithme/vectoriel et plus généralement pour des procédés quasi linéaires vectoriels. La troisième partie porte sur certains approximants de type Padé de fonctions entières. Des résultats sur l'accélération sont établis. La dernière partie fait le lien entre biorthogonalité, procédé de Gram-Schmidt, système linéaire et interpolation.
18

New formulae for higher order derivatives and a new algorithm for numerical integration

Slevinsky, Richard Unknown Date
No description available.
19

Frações contínuas que correspondem a séries de potências em dois pontos

Lima, Manuella Aparecida Felix de [UNESP] 19 February 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:26:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-19Bitstream added on 2014-06-13T20:27:27Z : No. of bitstreams: 1 lima_maf_me_sjrp.pdf: 528569 bytes, checksum: 3cad2d8f7175d945b2ead7fb45a5c4e1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O principal objetivo deste trabalho é estudar métodos para construir os numeradores e denominadores parciais da fração contínua que corresponde a duas expansões em série de potências de uma função analítica f(z); em z =0 e em z = 00. / The main purpose of this work is to two series expansions of an analytic function f(z); in z =0 and z =00 simultaneously. Furthermore we considered the case when there are zero coefficients in the series and also whwn there is symmetry in the coefficients of the two series. Some examples are given.
20

Application of Holomorphic Embedding to the Power-Flow Problem

January 2014 (has links)
abstract: With the power system being increasingly operated near its limits, there is an increasing need for a power-flow (PF) solution devoid of convergence issues. Traditional iterative methods are extremely initial-estimate dependent and not guaranteed to converge to the required solution. Holomorphic Embedding (HE) is a novel non-iterative procedure for solving the PF problem. While the theory behind a restricted version of the method is well rooted in complex analysis, holomorphic functions and algebraic curves, the practical implementation of the method requires going beyond the published details and involves numerical issues related to Taylor's series expansion, Padé approximants, convolution and solving linear matrix equations. The HE power flow was developed by a non-electrical engineer with language that is foreign to most engineers. One purpose of this document to describe the approach using electric-power engineering parlance and provide an understanding rooted in electric power concepts. This understanding of the methodology is gained by applying the approach to a two-bus dc PF problem and then gradually from moving from this simple two-bus dc PF problem to the general ac PF case. Software to implement the HE method was developed using MATLAB and numerical tests were carried out on small and medium sized systems to validate the approach. Implementation of different analytic continuation techniques is included and their relevance in applications such as evaluating the voltage solution and estimating the bifurcation point (BP) is discussed. The ability of the HE method to trace the PV curve of the system is identified. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2014

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