Search
Now showing items 1-10 of 62
Measurements and modelling of high-frequency acoustic scattering by a rough seafloor and sea surface
(NURC, 2009/12)
Acoustic scattering by a rough, possibly dynamic interface is experimentally studied by insonifying the seabed and the sea surface at high frequency at various incidentangles. A directional source working at 300 kHz was ...
Areal seabed classification using backscatter angular response at 95kHz
(NATO. SACLANTCEN, 1997)
A sediment classification scheme is developed based on the angular response (AR) of the seabed backscatter strength. The AR is characterised based on its mean level and slope over predefined angular sectors, and the presence ...
A note on attenuation and dispersion in marine sediments
(NATO. SACLANTCEN, 1989/04)
From the more recent investigations reported ill the literature,
Modelling scattering from partially buried cylinders = Acoustic scattering from cylindrical objects embedded between two half-spaces/The computation of the scattered pressure field from a cylinder embedded between two half-spaces = The computation of the scattered pressure field from a cylinder embedded between two half-spaces with different densities
(NATO. SACLANTCEN, 1996/12)
1. A boundary integral equation method is presented for the computation of the acoustic field scattered from a cylindrical object which is totally within the water column, totally buried in sediment, or partially buried. ...
Seabed characterization by inversion of parametric sonar data: selection of the cost function
(NATO. SACLANTCEN, 1997)
A class of possible cost functions to be used in model-based estimation of bottom parameters from highfrequency backscatter signals is introduced. The cost is based on the properttes of the signal in the wavelettransformed ...
Bottom time spread and bistatic scattering by rough basalt
(NATO. SACLANTCEN, 1993/08)
Scattering from oceanic basalt affects low-frequency active sonar systems in at least two important ways: (1) Significant time, angle and frequency spreading reduces target echo levels when systems over-resolve the spread; ...
Shallow-water seafloor characterization for high-frequency multibeam echosounder: image segmentation using angular backscatter
(NATO. SACLANTCEN, 1997)
Sonar images from multibeam echosounders are submitted to various degradations, partly due to the sensor itself: Signal artefacts and corresponding corrections are presented, both for signal processing and for array ...
The effect source movements on shallow water bottom backscatter
(NATO. SACLANTCEN, 1997)
The time-evolution model BORIS is used to study the effects of source movements on bottom backscatter. Changes in the backscattend time domain signals as functions of source depth, position and incident angles are simulated ...
Shallow-water sound transmission measurements taken on the New Jersey continental shelf
(NATO. SACLANTCEN, 1993/08)
Calibrated acoustic measurements were made under calm sea state conditions on the New Jersey shelf near the AMCOR 6010 borehole, a surveyed area with known geophysical properties. The experiment was conducted in 73 m water ...
High-resolution characterization of seafloor sediments for modeling acoustic backscatter
(NATO. SACLANTCEN, 1997)
Quantitative information on fine-scale sediment inhomogeneity is extremely scarce and sorely needed for developing realistic volume scattering models. To address this deficiency, we present a novel approach for sediment ...