碩士 / 國立臺灣大學 / 工程科學及海洋工程學研究所 / 97 / 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.
| Identifer | oai:union.ndltd.org:TW/097NTU05345020 |
| Date | January 2009 |
| Creators | Tsung-Sheng Kuo, 郭宗聖 |
| Contributors | 黃維信 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 61 |
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