Conjugate Gradient Methods
Mostrando 1-11 de 11 artigos, teses e dissertações.
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1. Heuristics for implementation of a hybrid preconditioner for interior-point methods
This article presents improvements to the hybrid preconditioner previously developed for the solution through the conjugate gradient method of the linear systems which arise from interior-point methods. The hybrid preconditioner consists of combining two preconditioners: controlled Cholesky factorization and the splitting preconditioner used in different pha
Pesquisa Operacional. Publicado em: 2011-12
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2. Estudo de alguns metodos determinsticos de otimização irrestrita / Study of some deterministic methods for unconstrained optimization
In this work some classical methods of linear search for unconstrained optimization are studied. The main mathematical formulations for the optimization problem are presented. Two strategies, linear search and trust region, for the algorithm to move from one iteration to another are discussed. Furthermore, the main considerations about the choice of step len
Publicado em: 2010
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3. A new approach for estimation of PVT properties of pure gases based on artificial neural network model
Equations of state are useful for description of fluid properties such as pressure-volume-temperature (PVT). However, the success estimation of such correlations depends mainly on the range of data which have originated. Therefore new models are highly required. In this work a new method is proposed based on Artificial Neural Network (ANN) for estimation of
Brazilian Journal of Chemical Engineering. Publicado em: 2009-03
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4. New versions of the Hestenes-Stiefel nonlinear conjugate gradient method based on the secant condition for optimization
Based on the secant condition often satisfied by quasi-Newton methods, two new versions of the Hestenes-Stiefel (HS) nonlinear conjugate gradient method are proposed, which are descent methods even with inexact line searches. The search directions of the proposed methods have the form d k = - θkg k + βkHSd k-1, or d k = -g k + βkHSd k-1+ θky k-1. When ex
Computational & Applied Mathematics. Publicado em: 2009
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5. Comparação de métodos de otimização para o problema de ajuste de histórico em ambientes paralelos
The process of history matching aims on the determination of the models parameters from a petroleum reservoir. Once adjusted, the models can be used for the prediction of the reservoir behavior. This work presents a comparsion of dierent optimization methods for this problem s solution. Derivative based methods are compared to a genetic algorithm. In particu
Publicado em: 2009
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6. A new algorithm of nonlinear conjugate gradient method with strong convergence
The nonlinear conjugate gradient method is a very useful technique for solving large scale minimization problems and has wide applications in many fields. In this paper, we present a new algorithm of nonlinear conjugate gradient method with strong convergence for unconstrained minimization problems. The new algorithm can generate an adequate trust region rad
Computational & Applied Mathematics. Publicado em: 2008
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7. Comparative study of spectral steplengths and nonmonotone linear searches / Estudo comparativo de passos espectrais e buscas lineares não monótonas
The Spectral Gradient method, introduced by Barzilai and Borwein and analized by Raydan for unconstrained minimization, is a simple method whose performance is comparable to traditional methods, such as conjugate gradients. Since the introduction of method, as well as its extension to minimization of convex sets, there were introduced various combinations of
Publicado em: 2008
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8. Método das direções conjugadas no núcleo das restrições para minimização de uma função quadrática sujeita a restrições lineares de igualdade
Este trabalho trata do problema de minimizar uma função quadrática sujeita a restrições lineares de igualdade que aparece em geral como um subproblema nos problemas de programação não linear com restrições. Uma grande variedade de algoritmos de otimização com restrições lineares e não lineares usam resolver a cada iteração um subproblema da
Publicado em: 2005
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9. New developments on BE/BE multi-zone algorithms based on krylov solvers: applications to 3D frequency-dependent problems
In this paper, new developments concerning the use of BE/BE coupling algorithms for solving 3D time-harmonic problems are reported. The algorithms are derived by considering different iterative solvers. Their chief idea is to work with the global sparse matrix of the coupled system, however without considering the many zero blocks associated with the non-cou
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2004-06
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10. Modelo para analise de deslocamento miscivel no meio poroso usando a teoria dos canais de fluxo
This work describes a model for the analysis of a two-components, single phase miscible displacement, considering both homogeneous and heterogeneous reservoirs, and constant total mobility (M =1). The streamtubes are computed from the solution of the partial differential equation of the Stream Function. The discretization of such equation results in a pentad
Publicado em: 1998
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11. On the use of low-frequency normal modes to enforce collective movements in refining macromolecular structural models
As more and more structures of macromolecular complexes get solved in different conditions, it has become apparent that flexibility is an inherent part of their biological function. Normal mode analysis using simplified models of proteins such as the elastic network model has proved very effective in showing that many of the structural transitions derived fr
National Academy of Sciences.