Estudo do aumento do desempenho de um sistema de tomografia de impedância elétrica através do método de otimização topológica. / Increasing electrial impedance tomography system performance through the topology optimization method.

AUTOR(ES)

Luís Augusto Motta Mello

DATA DE PUBLICAÇÃO

2010

RESUMO

Electrical Impedance Tomography images the interior of a body based on electrical quantities measured on the surface of it. Mathematically, the technique finds the electric admittivity distribution in a given body model which reproduces the boundary measurements of electric currents and potentials on electrodes attached to that body. Therefore, the admittivity distribution is the solution of a non-linear and ill-posed problem, which is unstable and have local minima, requiring specific inversion techniques. Electrical Impedance Tomography systems which obtain images corresponding to absolute values present limitations. For instance, the results are usually smooth and underestimated, the sensitivity to errors in the positioning of electrodes and wrong values of contact parameters and the sensitivity to measurement noise are high, the data processing time is high, etc. In this work, techniques based on the Topology Optimization Method intended for improving the performance of the particular Electrical Impedance Tomography system applied to absolute images are proposed and evaluated. More specifically, the following techniques are evaluated: 1) a method intended to obtain contact parameters together with images, and a regularization method based on the explicit control of the spatial variation regarding the image, 2) a formulation applied to handle uncertainties, 3) a formulation applied to correct the position of electrodes, 4) a formulation applied to design electrodes, 5) and a new solver for large-scale linear systems. Results show the effectiveness of most of the proposed techniques, and suggest new research topics in Electrical Impedance Tomography.

ASSUNTO(S)

otimização topológica posicionamento de eletrodos topology optimization medical images electrodes placement electrical impedance tomography tomografia de impedância elétrica método de otimização topológica baseado em confiabilidade solução de sistemas lineares de larga escala large-scale linear system solution reliability-based topology optimization imagens médicas

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