碩士 / 國立中山大學 / 海下技術研究所 / 86 / The main theme of this thesis is to study plane wave scattering from perfectly reflecting rough surfaces attempting to simulate the scenarios of wave scattering from rough sea surface and seabed. From the practical point of view, the ocean surface separating the air and water may be considered as a perfectly reflecting pressure-release surface because of the strong impedance contrast between these two media. As for the seabed, it is assumed to be a rigid rough surface. This assumption may not be completely acceptable because in reality the seafloor, particularly the upper part of the sediment layer, is a medium with finite bulk and shear modulus so that the interface allows energy to be penetrated into bottom through both compressional and shear waves. However, in this study, we shall approximate the seafloor as a rigid bottom, and consider the effect of roughness on the acoustic scattering from such interface. A complete model which considers wave scattering from a rough interface overlying on a penetrable medium with gradual variation of acoustic properties is included and discussed in the thesis. Further investigation will soon be undertaken.The rough surfaces under consideration are described by various statistical quantities, including height probability function, correlation function, power spectrum, and realization. To suit for the types of rough surfaces of our interests, we place our emphases on three kinds of power spectrum: the Pierson-Moskowitz spectrum, the Gaussian spectrum, and the Goff-Jordan spectrum. A realization process for the power spectrum is developed. The scattered pressure fields, the scattering coefficient, and the correlation function are generated and analyzed for a wide range of controlling parameters.Despite the fact that the scattering from a single rough interface is an old subject which has been studied extensively, most studies have been concerned with the solution of spectral distribution of the scattered field. Little has been done in applying modern data processing software such as matlab in solving these problems in time domain. The dynamic simulation of the scattered fields and other acoustic phenomena provide a vivid presentation of the acoustic fields, which not only eases the way of communication with others but also provides a perfect tool for classroom demonstration. Therefore, it is highly desirable that a complete toolbox in acoustic wave propagation in an oceanic environment is available, and, in this regard, the present study serves as an initiation of the development along this line.-1 aAcoustic Wave Scattering From Rough Sea Surface and Seabed
| Identifer | oai:union.ndltd.org:TW/086NSYSU637004 |
| Date | January 1998 |
| Creators | Huang,Chen-Fen, 黃千芬 |
| Contributors | Liu,Jin-Yuan, 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 | 122 |
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