By using a ray method, a physical model that the backscattering of a tube is simplilied into reflection of a plane wave on layered media is suggested and reconstruction formulas of the parameters of a metallic tube co...By using a ray method, a physical model that the backscattering of a tube is simplilied into reflection of a plane wave on layered media is suggested and reconstruction formulas of the parameters of a metallic tube covered with sound-absorbing materials under the conditions of high frequency, fard field and thin tube are given. The internal and external radii of an aluminium tube filled by water or air and thickness of the covered material are reconstructed by using computer simulation and experimellts. The theoretical tesults obtained by this method are supported by experiments.展开更多
The remote measurement of the vertical distribution of acoustical parameters of the sea bottom is an inverse method in acoustics. The existing methods can be divided into two types: the wave method and the ray method....The remote measurement of the vertical distribution of acoustical parameters of the sea bottom is an inverse method in acoustics. The existing methods can be divided into two types: the wave method and the ray method. The former usually does not apply to cases with discontinuity in acoustical parameter profiles[1] , whereas the latter usually ignores the contributions made by multiple reflections, resulting in the appearance of pseudo interfaces. However, under certain practical circumstances, the ray method can produce satisfactory results[2,3]. In this paper, at first we use the conception of equitime layer thickness to obtain the pulse response iteration method. The anti-interference capability of this method is poor. In order to improve this capability, we develope the sample iteration method and the sample-averaging iteration method. The sample-averaging iteration method introduces a way of statistical averaging, which can further improve the anti-interference capability.展开更多
In this paper, we first discuss the direct scattering problem for a cylindrical homogeneous clastic tube with a geometrical method, and then study the inverse problem. The heuristics of B-F procedure (Best-First searc...In this paper, we first discuss the direct scattering problem for a cylindrical homogeneous clastic tube with a geometrical method, and then study the inverse problem. The heuristics of B-F procedure (Best-First search strategy) is used. The inner radius, outer radius, sound velocitics of the tube and sound velocity of the internal medium are obtained with this heuristics.展开更多
文摘By using a ray method, a physical model that the backscattering of a tube is simplilied into reflection of a plane wave on layered media is suggested and reconstruction formulas of the parameters of a metallic tube covered with sound-absorbing materials under the conditions of high frequency, fard field and thin tube are given. The internal and external radii of an aluminium tube filled by water or air and thickness of the covered material are reconstructed by using computer simulation and experimellts. The theoretical tesults obtained by this method are supported by experiments.
文摘The remote measurement of the vertical distribution of acoustical parameters of the sea bottom is an inverse method in acoustics. The existing methods can be divided into two types: the wave method and the ray method. The former usually does not apply to cases with discontinuity in acoustical parameter profiles[1] , whereas the latter usually ignores the contributions made by multiple reflections, resulting in the appearance of pseudo interfaces. However, under certain practical circumstances, the ray method can produce satisfactory results[2,3]. In this paper, at first we use the conception of equitime layer thickness to obtain the pulse response iteration method. The anti-interference capability of this method is poor. In order to improve this capability, we develope the sample iteration method and the sample-averaging iteration method. The sample-averaging iteration method introduces a way of statistical averaging, which can further improve the anti-interference capability.
文摘In this paper, we first discuss the direct scattering problem for a cylindrical homogeneous clastic tube with a geometrical method, and then study the inverse problem. The heuristics of B-F procedure (Best-First search strategy) is used. The inner radius, outer radius, sound velocitics of the tube and sound velocity of the internal medium are obtained with this heuristics.
