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Acoustic underwater acoustics as a branch of the main research the spread of sound waves in the water, radiation, the scattering and receive the law to solve the acoustic problems associated with underwater target detection and information transmission process. Study the scattering properties of sound waves to the discovery and summary of acoustic wave propagation in the water to follow the law and the corresponding mechanism. Common underwater scattering geometry of the body, such as submarines, torpedoes, mines, reef of the same, but generally speaking, they are either close to spherical, or close to cylindrical, so for convenience of mathematical treatment, usually approximate seen as a sphere or cylinder. This approximation process, tend to make the mathematical operations greatly simplified, while the results obtained also apply to the actual scattering body, and thus this study the scattering characteristics of the underwater unsteady three-dimensional canonical elastic body such as a sphere, spherical, cylindrical, cylindrical shell . This paper first reviews the history of the development of the water acoustics, and a brief introduction to the underwater typical elastomer backscatter problems at home and abroad theoretical research profiles and numerical methods. In the far-field acoustic scattering calculation underwater elastic shell, the general ray method, this method is more suitable for high frequency. According to PWS (partial wave series) echo formula to calculate the shape function of the sphere, spherical, cylindrical and cylindrical shells. Comparing these shape functions found the shell significantly enhanced in the mid-range called IF enhance phenomenon, and several other elastomers are not in a similar situation. The study found that IF Enhancement is by La Mubo in subsonic antisymmetric a0? Waves cause. In this paper, corrected ray theory to calculate the different thickness of the shell s0, a 0?, A 0-wave dispersion curves, and estimate the dispersion curves of different thickness of the shell a0? Dimensionless frequency wave echo contribution maximum xp and the delay factor corresponding to dimensionless ΔT 0l, analysis of these values ??are found, the spherical shell of thickness to diameter ratio h / a, the dimensionless delay factor ΔT 0l xp largest enhanced when the frequency of approximately a linear relationship, and in accordance with this an attribute derived two linear formulas used to estimate the thin shell of radius and thickness. Also proposed using high-frequency short-time sine wave echo estimate a0? The wave frequency wm p and the corresponding delay time Δt 0ml simple. Using this method may be a more accurate estimate of the underwater thin spherical shell radius and thickness values, has a certain value in engineering.
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