Improved harmony search for detection with photon density wave

Based on the solution of the diffusion equation for photon density wave in rectangular coordinates, a model of a three dimensional cubic tissue with an abnormity for the inverse problem is established. By use of the analytic expression of the photon density and the least squares (LS) method, the objective function for solving the inverse problem is constructed. Then, an adaptive Harmony Search (HS) is presented and employed to seek the possible solution. In the improved algorithm, the harmony memory considering rate (HMCR) and the pitch adjusting rate (PAR) are adjusted in the searching process to obtain more accurate solution of the detection problem. The numerical experiments for comparisons of the conventional HS and the adaptive HS are given. The results show that the improved algorithm can be used to localize the abnormity embedded in the tissue with a good agreement with the presupposed location parameters. It can be concluded that AHS algorithm is more effective than the conventional HS for the inverse problems similar to the detection using photon density wave.