tailieunhanh - Genetic algorithms and smoothing filters in solving the geophysical inversion problem

The combination of genetic algorithms, smoothing filters and geophysical tomography is used in solving the geophysical inversion problem. This hybrid technique is developed to improve the results obtained by using genetic algorithms only. The application of smoothing filters can improve the performance of GA implementation for solving the geophysical inversion problem. Some test-examples and the obtained comparative results are presented. | Yugoslav Journal of Operations Research 12 (2002), Number 2, 215-226 GENETIC ALGORITHMS AND SMOOTHING FILTERS IN SOLVING THE GEOPHYSICAL INVERSION PROBLEM Vesna [E[UM Department of Mathematics, Faculty of Mechanical Engineering University of Belgrade, Belgrade, Yugoslavia Du{an TO[I] Faculty of Mathematics University of Belgrade, Belgrade, Yugoslavia Abstract: The combination of genetic algorithms, smoothing filters and geophysical tomography is used in solving the geophysical inversion problem. This hybrid technique is developed to improve the results obtained by using genetic algorithms only. The application of smoothing filters can improve the performance of GA implementation for solving the geophysical inversion problem. Some test-examples and the obtained comparative results are presented. Keywords: Genetic algorithms, smoothing filters, tomography. 1. INTRODUCTION Tomographic reconstruction techniques are used in different fields: geophysical exploration, medical imaging, astronomy etc. By using geophysical tomography, the characteristics of an underground region between two boreholes can be determined. The tomographic technique provides a means of estimating P-wave velocity in the region between two boreholes. In the time measuring procedure, wave transmitters are placed in one borehole and receivers in the other one in order to collect the first-arrival traveltime data. By using the first-arrival traveltime data, the distribution of wave velocities along a plan between two boreholes is calculated and displayed as a digital picture. Because of that, this problem is known as Image Reconstruction from Projections. The standard tomographic procedures for solving this problem are based on the decomposition of the cross-hole area into a number of cells and an assumption of straight raypaths. The details about the application of V. [e{um, D. To{i} / Genetic Algorithms and Smoothing Filters 216 geophysical tomography and basic notions related to this method