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Penetration of acoustic waves into sandy seafloors at low grazing angles: the Helmholtz-Kirchhoff approach
(NATO. SACLANTCEN, 1998/08)
The Helmholtz-Kirchhoff integral is applied to model the penetration of sound waves into sandy seafloors at grazing angles above and below the critical angle. Although the conditions for the validity
Detection of buried objects in the seabed: a simple model study
(NATO. SACLANTCEN, 1998/10)
The problem of detecting an object buried in the seabed is studied by means of a simple model. In this model, the object is a rigid sphere buried in a bottom modelled as a fluid half space. The scattered field is determined ...
Modelling of scattering by partially buried elastic cylinders
(NATO. SACLANTCEN, 1998/02)
The work of a previous memorandum on the modelling of scattering by a partially buried cylinder is extended to allow the cylinder to have full elasticity (and not just be a fluid structure as in the previous work). The ...
Mechanisms for subcritical penetration into a sandy bottom: experimental and modelling results
(NATO. SACLANTCEN, 1998/05)
This paper presents the results of a recent study whose overall objectives are to determine the mechanism(s) contributing to subcritical acoustic penetration into ocean sediments, and to quantify the results for use in ...
Coupled-mode modelling of acoustic scattering from three-dimensional, axisymmetric objects
(NATO. SACLANTCEN, 1997/01)
In this memorandum a coupled-mode method for computing the wavefield scattered by three-dimensional, axisymmetric objects is presented. The method provides a unified approach to solving three-dimensional scattering problems ...
Generic Oceanographic Array Technologies (GOATS)'98: bi-static seabed scattering measurements using autonomous underwater vehicles
(NATO. SACLANTCEN, 1998/10)
The GOATS'98 experiment was performed May 5-29, 1998 in shallow water off Marciana Marina, on the island of Elba, Italy. The experiment addressed some of the fundamental issues associated with using the new Autonomous Ocean ...
Physics of 3-D scattering from rippled seabeds and buried targets in shallow water
(NATO. SACLANTCEN, 1998/05)
The new OASES-3D code developed at MIT is used to investigate the spatial and temporal characteristics of reverberation from rippled seabeds insonified by narrow beam sonars such as the TOPAS parametric source. It is shown ...
Scattering by spheres buried in sediment
(NATO. SACLANTCEN, 1997/01)
In this report the scattering of acoustic energy by an elastic sphere buried in sediment is examined. The geoacoustic model consists of two homogeneous fluid halfspaces separated by an intermediate layer. The source field ...
Modelling acousto-elastic waveguide/object scattering with the Rayleigh hypothesis
(NATO. SACLANTCEN, 1998/06)
In this memorandum the plane wave scattering matrices for a range-dependent seabed and upper free surface are computed using the