Forward Modeling And Data Inversion For Beam Propagation In A Stratified Medium. Ii: Numerical Results

The general theory of both forward and inverse modelings for beam propagation in stratified media developed in Part I of this presentation [I-Tai Lu, J. Acoust. Soc. Am. 91, 1228-1238 (1992)] is examined in detail by numerical simulations. Modes, collective beams, and conventional beams have been employed to calculate the beam-excited wave phenomena in both piecewise-homogeneous and arbitrarily inhomogeneous layered media. These algorithms are formulated in the same framework and yield essentially the same results. Efficient data inversion procedures to minimize least-square errors for localizing a beam source are also presented and examined by numerical simulations. The conventional modal-filtering procedure using inner products of the received signals with the orthonormal eigenfunctions is proved to be a special case of a weighted least-square scheme.