A conjugate gradient type method for linear ill posed problems with operator perturbations

A conjugate gradient type method for linear ill posed problems with operator perturbations PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 46

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A conjugate gradient type method for linear ill posed problems with operator perturbations

A conjugate gradient type method for linear ill posed problems with operator perturbations PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 46

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Book Description


Conjugate Gradient Type Methods for Ill-Posed Problems

Conjugate Gradient Type Methods for Ill-Posed Problems PDF Author: Martin Hanke
Publisher: CRC Press
ISBN: 1351458337
Category : Mathematics
Languages : en
Pages : 144

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Book Description
The conjugate gradient method is a powerful tool for the iterative solution of self-adjoint operator equations in Hilbert space.This volume summarizes and extends the developments of the past decade concerning the applicability of the conjugate gradient method (and some of its variants) to ill posed problems and their regularization. Such problems occur in applications from almost all natural and technical sciences, including astronomical and geophysical imaging, signal analysis, computerized tomography, inverse heat transfer problems, and many more This Research Note presents a unifying analysis of an entire family of conjugate gradient type methods. Most of the results are as yet unpublished, or obscured in the Russian literature. Beginning with the original results by Nemirovskii and others for minimal residual type methods, equally sharp convergence results are then derived with a different technique for the classical Hestenes-Stiefel algorithm. In the final chapter some of these results are extended to selfadjoint indefinite operator equations. The main tool for the analysis is the connection of conjugate gradient type methods to real orthogonal polynomials, and elementary properties of these polynomials. These prerequisites are provided in a first chapter. Applications to image reconstruction and inverse heat transfer problems are pointed out, and exemplarily numerical results are shown for these applications.

A Conjugate Gradient Type Method for Linear Ill Posed Problems with Operator Pertubations

A Conjugate Gradient Type Method for Linear Ill Posed Problems with Operator Pertubations PDF Author: Robert Plato
Publisher:
ISBN:
Category :
Languages : en
Pages : 46

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Regularization of ill-posed problems by conjugate gradient type methods

Regularization of ill-posed problems by conjugate gradient type methods PDF Author: Martin Hanke-Bourgeois
Publisher:
ISBN:
Category :
Languages : de
Pages : 69

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Operator Theory and Its Applications

Operator Theory and Its Applications PDF Author: Alexander G. Ramm
Publisher: American Mathematical Soc.
ISBN: 0821819909
Category : Mathematics
Languages : en
Pages : 594

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Book Description
Together with the papers on the abstract operator theory are many papers on the theory of differential operators, boundary value problems, inverse scattering and other inverse problems, and on applications to biology, chemistry, wave propagation, and many other areas."--BOOK JACKET.

Conjugate Gradient Algorithms and Finite Element Methods

Conjugate Gradient Algorithms and Finite Element Methods PDF Author: Michal Krizek
Publisher: Springer Science & Business Media
ISBN: 3642185606
Category : Science
Languages : en
Pages : 405

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Book Description
The position taken in this collection of pedagogically written essays is that conjugate gradient algorithms and finite element methods complement each other extremely well. Via their combinations practitioners have been able to solve complicated, direct and inverse, multidemensional problems modeled by ordinary or partial differential equations and inequalities, not necessarily linear, optimal control and optimal design being part of these problems. The aim of this book is to present both methods in the context of complicated problems modeled by linear and nonlinear partial differential equations, to provide an in-depth discussion on their implementation aspects. The authors show that conjugate gradient methods and finite element methods apply to the solution of real-life problems. They address graduate students as well as experts in scientific computing.

Regularization of Ill-Posed Problems by Iteration Methods

Regularization of Ill-Posed Problems by Iteration Methods PDF Author: S.F. Gilyazov
Publisher: Springer Science & Business Media
ISBN: 9401594821
Category : Mathematics
Languages : en
Pages : 348

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Book Description
Iteration regularization, i.e., utilization of iteration methods of any form for the stable approximate solution of ill-posed problems, is one of the most important but still insufficiently developed topics of the new theory of ill-posed problems. In this monograph, a general approach to the justification of iteration regulari zation algorithms is developed, which allows us to consider linear and nonlinear methods from unified positions. Regularization algorithms are the 'classical' iterative methods (steepest descent methods, conjugate direction methods, gradient projection methods, etc.) complemented by the stopping rule depending on level of errors in input data. They are investigated for solving linear and nonlinear operator equations in Hilbert spaces. Great attention is given to the choice of iteration index as the regularization parameter and to estimates of errors of approximate solutions. Stabilizing properties such as smoothness and shape constraints imposed on the solution are used. On the basis of these investigations, we propose and establish efficient regularization algorithms for stable numerical solution of a wide class of ill-posed problems. In particular, descriptive regularization algorithms, utilizing a priori information about the qualitative behavior of the sought solution and ensuring a substantial saving in computational costs, are considered for model and applied problems in nonlinear thermophysics. The results of calculations for important applications in various technical fields (a continuous casting, the treatment of materials and perfection of heat-protective systems using laser and composite technologies) are given.

Inverse Problems in the Mathematical Sciences

Inverse Problems in the Mathematical Sciences PDF Author: Charles W. Groetsch
Publisher: Springer Science & Business Media
ISBN: 3322992020
Category : Technology & Engineering
Languages : en
Pages : 159

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Book Description
Inverse problems are immensely important in modern science and technology. However, the broad mathematical issues raised by inverse problems receive scant attention in the university curriculum. This book aims to remedy this state of affairs by supplying an accessible introduction, at a modest mathematical level, to the alluring field of inverse problems. Many models of inverse problems from science and engineering are dealt with and nearly a hundred exercises, of varying difficulty, involving mathematical analysis, numerical treatment, or modelling of inverse problems, are provided. The main themes of the book are: causation problem modeled as integral equations; model identification problems, posed as coefficient determination problems in differential equations; the functional analytic framework for inverse problems; and a survey of the principal numerical methods for inverse problems. An extensive annotated bibliography furnishes leads on the history of inverse problems and a guide to the frontiers of current research.

Inverse Linear Problems on Hilbert Space and their Krylov Solvability

Inverse Linear Problems on Hilbert Space and their Krylov Solvability PDF Author: Noè Angelo Caruso
Publisher: Springer Nature
ISBN: 3030881598
Category : Mathematics
Languages : en
Pages : 150

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Book Description
This book presents a thorough discussion of the theory of abstract inverse linear problems on Hilbert space. Given an unknown vector f in a Hilbert space H, a linear operator A acting on H, and a vector g in H satisfying Af=g, one is interested in approximating f by finite linear combinations of g, Ag, A2g, A3g, ... The closed subspace generated by the latter vectors is called the Krylov subspace of H generated by g and A. The possibility of solving this inverse problem by means of projection methods on the Krylov subspace is the main focus of this text. After giving a broad introduction to the subject, examples and counterexamples of Krylov-solvable and non-solvable inverse problems are provided, together with results on uniqueness of solutions, classes of operators inducing Krylov-solvable inverse problems, and the behaviour of Krylov subspaces under small perturbations. An appendix collects material on weaker convergence phenomena in general projection methods. This subject of this book lies at the boundary of functional analysis/operator theory and numerical analysis/approximation theory and will be of interest to graduate students and researchers in any of these fields.

Conjugate gradient method for the solution of optimal control problems governed by weakly singular Volterra integral equations with the use of the collocation method

Conjugate gradient method for the solution of optimal control problems governed by weakly singular Volterra integral equations with the use of the collocation method PDF Author: Henry Ekah-Kunde
Publisher: GRIN Verlag
ISBN: 3668494150
Category : Mathematics
Languages : en
Pages : 29

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Book Description
Seminar paper from the year 2015 in the subject Mathematics - Applied Mathematics, grade: A, , language: English, abstract: In this research, a novel method to approximate the solution of optimal control problems governed by Volterra integral equations of weakly singular types is proposed. The method introduced here is the conjugate gradient method with a discretization of the problem based on the collocation approach on graded mesh points for non linear Volterra integral equations with singular kernels. Necessary and sufficient optimality conditions for optimal control problems are also discussed. Some examples are presented to demonstrate the efficiency of the method.