C J S Alves
Universidade de Lisboa, Mathematics, Faculty Member
- Professor at ULisboa - IST.edit
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This volume presents a wide range of medical applications that can utilize mathematical computing. This work grew out of a workshop on optimization which was held during the 2005 CIM Thematic Term on Optimization in Coimbra, Portugal. It... more
This volume presents a wide range of medical applications that can utilize mathematical computing. This work grew out of a workshop on optimization which was held during the 2005 CIM Thematic Term on Optimization in Coimbra, Portugal. It provides an overview of the state-of-the-art in optimization in medicine and will serve as an excellent reference for researchers in the medical computing community and for those working in applied mathematics and optimization.
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ABSTRACT
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This paper presents a computationally fast methodology for the estimation of spatial and transient unknown thermal contact conductance between sandwiched materials, using non-intrusive measurements. The methodology is formulated in such a... more
This paper presents a computationally fast methodology for the estimation of spatial and transient unknown thermal contact conductance between sandwiched materials, using non-intrusive measurements. The methodology is formulated in such a way that the spatial and temporal variations of the unknown function are obtained simply by solving a linear system, whose solution vector is composed of integrals containing measured temperatures and known heat fluxes applied at an external boundary. Good estimates are obtained, even for functions containing discontinuities in both time and space. Simulated measurements with and without errors are considered, showing very good results.
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Summary In this work we apply the Method of Fundamental Solutions (MFS) to the numerical calculation of eigenfrequencies and eigenmodes of 3D simply connected domains. This meshless method was considered for 2D shapes with simply geometry... more
Summary In this work we apply the Method of Fundamental Solutions (MFS) to the numerical calculation of eigenfrequencies and eigenmodes of 3D simply connected domains. This meshless method was considered for 2D shapes with simply geometry (cf. (8)) and ex- tended for a general 2D simply connected shape (cf. (1)). Here the application to 3D simply connected domains is analysed. We propose a choice of collocation and source points in 3D adapted from the algorithm presented in (1). Some numerical examples are considered to illustrate the convergence and the good approximations obtained with the proposed algorithm.
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Density results using an infinite number of plane acoustic waves allow to de-rive meshless methods for solving the homogeneous or the nonhomogeneous Helmholtz equation. In this work we consider the numerical simulation of acoustic source... more
Density results using an infinite number of plane acoustic waves allow to de-rive meshless methods for solving the homogeneous or the nonhomogeneous Helmholtz equation. In this work we consider the numerical simulation of acoustic source problems in a bounded domain using this method. We present several tests comparing with the method of fundamental solutions and a recent extension to nonhomogeneous problems.
A Dirichlet boundary value problem (BVP) for the Laplace equation will be considered in a bounded domain with corners. Two distinct types of numerical methods will be applied for the solution of this problem. A modification of the... more
A Dirichlet boundary value problem (BVP) for the Laplace equation will be considered in a bounded domain with corners. Two distinct types of numerical methods will be applied for the solution of this problem. A modification of the Boundary Element Method (BEM), as presented in ...
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Page 1. The Method of Fundamental Solutions applied to a heat conduction inverse problem Carlos JS Alves∗, Nuno FM Martins ∗Instituto Superior Técnico Avenida Rovisco Pais, 1096 Lisboa Codex, Portugal calves@math ...
Abstract In this work, we address a problem of recovering a boundary condi-tion on an elastic cavity from a single boundary measurement on an external part of the boundary. The boundary condition is given by a Robin condition and we aim... more
Abstract In this work, we address a problem of recovering a boundary condi-tion on an elastic cavity from a single boundary measurement on an external part of the boundary. The boundary condition is given by a Robin condition and we aim to identify its Robin coefficient ...
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This volume presents a wide range of medical applications that can utilize mathematical computing. This work grew out of a workshop on optimization which was held during the 2005 CIM Thematic Term on Optimization in Coimbra, Portugal. It... more
This volume presents a wide range of medical applications that can utilize mathematical computing. This work grew out of a workshop on optimization which was held during the 2005 CIM Thematic Term on Optimization in Coimbra, Portugal. It provides an overview of the state-of-the-art in optimization in medicine and will serve as an excellent reference for researchers in the medical computing community and for those working in applied mathematics and optimization.
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A CIP Catalogue record for this book is available from the Library of Congress. ISBN 978-1-4020-6094-6 (HB) ISBN 978-1-4020-6095-3 (e-book) Published by Springer, PO Box 17, 3300 AA Dordrecht, The Netherlands. www. springer. com Printed... more
A CIP Catalogue record for this book is available from the Library of Congress. ISBN 978-1-4020-6094-6 (HB) ISBN 978-1-4020-6095-3 (e-book) Published by Springer, PO Box 17, 3300 AA Dordrecht, The Netherlands. www. springer. com Printed on acid-free paper ...
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Page 1. Boundary integral formulae for the reconstruction of electric and electromagnetic inhomogeneities of small volume H. Ammari, S. Moskow and MS Vogelius March 30, 2000 1 Introduction The problem of determining ...
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The classical method of fundamental solutions (MFS) has only been used to approximate the solution of homogeneous PDE problems. Coupled with other numerical schemes such as domain integration, dual reciprocity method (with polynomial or... more
The classical method of fundamental solutions (MFS) has only been used to approximate the solution of homogeneous PDE problems. Coupled with other numerical schemes such as domain integration, dual reciprocity method (with polynomial or radial basis functions interpolation), the MFS can be extended to solve the nonhomogeneous problems. This paper presents an extension of the MFS for the direct approximation of Poisson and nonhomogeneous Helmholtz problems. This can be done by using the fundamental solutions of the associated eigenvalue equations as a basis to approximate the nonhomogeneous term. The particular solution of the PDE can then be evaluated. An advantage of this mesh-free method is that the resolution of both homogeneous and nonhomogeneous equations can be combined in a unified way and it can be used for multiscale problems. Numerical simulations are presented and show the quality of the approximations for several test examples.
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Abstract. We consider an isotropic Lame system for an elastic medium consisting of finitely many imperfections of small diameter, embedded in a homogeneous reference medium. The Lame co-efficients of the imperfections are different from... more
Abstract. We consider an isotropic Lame system for an elastic medium consisting of finitely many imperfections of small diameter, embedded in a homogeneous reference medium. The Lame co-efficients of the imperfections are different from those of the background medium. First, ...