Browsing CMRE Publications by Issue Date
Now showing items 541-560 of 882
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An automated instrument for testing and monitoring oceanographic mooring cables and ropes
(NATO. SACLANTCEN, 1997/09)Underwater acoustic experiments at the NATO SACLANT Undersea Research Centre, La Spezia, Italy (SACLANTCEN) are largely dependent on moored and towed instrumentation. Every year up to 500 cable terminations am made and ... -
Resonance scattering analysis by autoregressive models applied to air-filled, cylindrical, thin walled shells in water
(NATO. SACLANTCEN, 1997/10)Autoregressive (AR) parametric spectral estimation of the scatterer transfer function is applied to the analysis of acoustic scattering by elastic objects. In accordance with Resonance Scattering Theory (RST), the specular ... -
Channel sensitive processor: sensitivity and optimization study
(NATO. SACLANTCEN, 1997/10)The detection performance of the Channel-Sensitive Processor (CSP) has been tested in dense multipath conditions. It was demonstrated that, for a known propagation channel, the CSP outperforms the conventional matched ... -
Observations of Mediterranean flow into the Black Sea
(NATO. SACLANTCEN, 1997/10)Mediterranean Sea water inflow into the Black Sea is investigated using acoustic and oceanographic data obtained in the Black Sea exit region. The path of Mediterranean water and the resulting spreading on the continental ... -
An approach to robust map generation from multibeam bathymetric data
(NATO. SACLANTCEN, 1997/10)During the last twenty years, many multibeam bathymetric sonars have been produced. The instrumentation is usually accompanied by a system able to produce a seafloor map from the sonar data. There are also several public ... -
Comparison of a time domain spectral collocation method and the time-evolution backscatter model BORIS
(NATO. SACLANTCEN, 1997/11)A model based on the time-domain spectral collocation method has been implemented at Forsvarets -
A parametric synthetic aperure sonar for detection of proud and buried mines
(NATO. SACLANTCEN, 1997/12)This paper describes an experimental comparison between a parametric sonar and a conventional sonar for the detection of small objects on and in, the sea bed. Two experiments were performed in France (GESMA site) in October ... -
Reduction of low frequency active sonar clutter through image processing
(NATO. SACLANTCEN, 1997/12)Large numbers of false clutter detections arise in the use of low frequency active sonar for the detection of low Doppler submarine targets in shallow water. Traditional detection algorithms operate individually on each ... -
Modelling of scattering by objects on the seabed
(NATO. SACLANTCEN, 1997/12)This paper describes some of the theory and implementation issues of modeling the backscattered -
The application of parametric side scan sonar to the detection of proud and buried targets
(NATO. SACLANTCEN, 1998/01)This paper describes an experiment designed to evaluate the feasibility of using the TOPAS parametric transmitter mounted in side scan mode, for the detection of buried targets. The concept was tested with proud targets ... -
Channel sensitive processor: real data processing
(NATO. SACLANTCEN, 1998/02)The CSP is applied to data collected during the DUSS97 sea trial. A one-way geometry is used and the transmitted signal propagation time is known a priori. As predicted by analytical and simulation studies, the CSP detector ... -
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 ... -
Numerical simulation of the effects of bathymetry on underwater sound propagation using three-dimensional parabolic models
(NATO. SACLANTCEN, 1998/03)Two different three-dimensional parabolic equation (PE) methods are -
Broadband geo-acoustic inversion from sparse data using genetic algorithms: results from the 1997 Geo-Acoustic Inversion Workshop
(NATO. SACLANTCEN, 1998/03)Matched field acoustic inversion techniques were investigated -
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 ... -
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 ... -
Detection of buried objects at low grazing angles: preliminary experimental results
(NATO. SACLANTCEN, 1998/06)This report considers the acoustic detection of objects buried in the seabed, and especially the possibility of using subcritical insonification geometries in order to increase coverage rate. -
Oceanographic measurements of the West Black Sea: November 26 to December 14, 1995
(NATO. SACLANTCEN, 1998/06)Mediterranean water inflow into the Black Sea is investigated using acoustic and oceanographic data obtained in the Black Sea exit region. Temporal and spatial variability in the flow and their relation to atmospheric and ... -
Yellow Shark Spring '95: inversion results from sparse broadband acoustic measurements over a highly range dependent soft clay layer
(NATO. SACLANTCEN, 1998/06)In May 1995, SACLANTCEN performed broad-band (200-800 Hz) acoustic measurements in the Giglio basin off the coast of Italy as part of the Yellow Shark inversion experiments. In this paper, inversion of sparse, broad-band ... -
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