碩士 / 國立中山大學 / 海下技術研究所 / 89 / In the traditional analysis of acoustic wave propagation in an ocean waveguide, it's generally assumed that acoustic properties, including density and sound speed profile at seabed are taken to be constant. However, recent experimental data provided by Hamilton~(1980)~ have shown that the sediment layer in the seabed experiences a transitional change in which the density and the sound speed vary continuously from one value at the top to another at the bottom of the layer. The objective of this study is to investigate the surface-generated ambient noise in an isovelocity waveguide with a non-homogeneous fluid sediment layer.
The noise model was first proposed by Kuperman and Ingenito~(1980) in the study of surface-generated ambient noise using normal mode approach, and the model proposed by Robins (1993) in the study of the sediment layer change in which the density and the sound speed vary continuously. It is demonstrated that the noise intensity may be affected by the stratification mainly through the continuous spectrum, in that the continuous spectrum is equally important as the normal modes in the present analysis.
The continuous variation of the sediment layer reduces the contrast of the interface, which in turn affects the wavenumber spectrum, particularly in the continuous spectrum region. The results show that the horizontal correlation length of the noise field increases as that of the noise random sourse increase, but the vertical correlation length of the noise field decreases as that of the noise random sourse increase.
| Identifer | oai:union.ndltd.org:TW/089NSYS5637001 |
| Date | January 2001 |
| Creators | Shih-Tzung Hsu, 許世宗 |
| Contributors | Jin-Yuan Liu, 劉金源 |
| 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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