Simulated annealing for vertical magnetic dipole TEM ID inversion

摘要

Simulated annealing is one kind of global optimization methods, which needn't calculate Jacobian matrix, is less dependent on starting model and isn't easily trapped in local minima. Using Gaver-Stehfest transform, impulse response of magnetic induction excited by vertical magnetic dipole on the surface of layered medium was deduced from electric field in frequency domain. Simulated annealing was applied in TEM 1D inversion, numerical calculation model was two-layer geoelectric model. We demonstrate the simulated annealing flexibility for starting models by allowing the model parameters to vary in a large range (far away from the true model). For verifying the algorithm is suitable of TEM 1D inversion, the inversion starts from 10 different starting models and has 500 temperature reductions (iterations). All runs converge to the true parameters and the discrepancy between inversion results and true parameters are less than 3%. However, the efficiency of simulated annealing for TEM 1D inversion is low.