Biomedical subjects
Publications and source records attributed to G A Kyriacou.
A 32-electrode data collection system for Electrical Impedance Tomography (EIT) will be presented. In this system, the demodulator is a multiplexed sample and hold (S&H) circuit followed by a voltage difference stage. This configuration provides high CMRR due to the low (almost DC) operating frequency of the signals the difference stage is required to process.
In this paper an efficient finite-element method (FEM) algorithm for complicated three-dimensional (3D) layered type models has been developed. Its unique feature is that it can handle, with memory requirements within the abilities of a simple PC, arbitrarily shaped 3D elements. This task is achieved by storing only the non-zero coefficients of the sparse FEM system of equations. The algorithm is applied to the solution of the Laplace equation in models with up to 79 layers of trilinear general hexahedron elements. The system of equations is solved with the Gauss-Seidel iterative technique.
A modified perturbation method (MPM) arising from the replacement of the sensitivity matrix by the Jacobian matrix is presented. Our results have been made using an array processor board with four T-800 INMOS transputers. The numerical algorithm has been matched to the new system and the procedure reached a minimum 50 times faster than for a single PC/AT with mathematical co-processor. Several phantoms have been reconstructed. From the results one can see the applicability of the MPM algorithm to complicated models.