Simulation of Underwater Acoustic Propagation in Rugged Topography
Date Issued
2009
Date
2009
Author(s)
Kuo, Tsung-Sheng
Abstract
The purpose of this research is to improve the defect of numerical calculation of sound propagation in the rugged topography. In such a sea bed, some parameters become unable to obtain because of the affection of sharp corners or the large slope of the topography. In order to solve this problem, two methods, the Hilbert-Huang Transform and the Least Square Method are adopted to smooth the topography. In the first step, Empirical Mode Decomposition in the Hilbert-Huang Transform is used to obtain a new topography. Next, the Least Square Method is applied to calculate the cubic spline equations for the new topography. For comparison, the Fourier Transform Method is applied in some test cases. The simulation results indicate that the Gaussian Beam Method without smoothing works well in the mild variation region in topography. In the rugged regions, such as Baimianhua canyon and Kaoping canyon. The Gaussian Beam Method without the smoothing needs very dense beams in order to obtain the convergent results. However, when the topography is smoothed, a regular beam density is enough in the test areas.
Subjects
Hilbert-Huang Transform
Least Square Method
Gaussian Beam Method
Ray
Type
thesis
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