Research On Inversion Of Sea Bottom Parameters Using A Horizontal Line Array

Acoustic propagation in the oceans shallow waters is influenced by different environmental factors. The sea bottom often has the strongest effect on sound propagation and its properties are probably the most difficult things to be measured directly. The expected acoustic parameters can be extracted by inversion from the measurement of forward propagation of sound signal in sea duct, therefore inversion method has attracted much attention in these years.This paper is written based on the ray theory of acoustics, which had been developed earliest and has the simplest physical figure. The inversion model of the sea bottom parameters are established in nonparallel layered bottom, in which the sound velocity and the depth of each layer should be determined. Since Genetic Algorithms(GA) can be used for global search with self-consistent probability and can overcome the difficulties while solving nonlinear problems using linear methods, so it had been used to solve the nonlinear least square problem of inversion model, where the cost function has non-singular extrema. The global optimization or the second best solution had been obtained. At first, the forward prediction models are established by simulation to get the parameters needed for inversion. It had been proved theoretically by simulation results that the inversion method is effective for determination of acoustic parameters in sea bottom.In chapter 5 the experiment data in Songhua Lake are processed by inversion method, the results give a good proof that this method can be used to reconstruct the sound velocity and the depth of layered bottom.