Browsing by Subject "Acoustic models"
Now showing items 41-60 of 84
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Multipath field representation for seabed parameter extraction using backscatter data from shadow zones
(NATO. SACLANTCEN, 1997)Inversion strategies for bottom parameter estimation in shallow water impose stringent requirements on accuracy and speed of acoustic models. We highlight the importance of second order effects as first order determinants ... -
Notes on the interpretation of ambient noise statistics
(NATO. SACLANTCEN, 1982/06)Interpretation of statements about the character of ambient sea noise, as well as schemes to measure or model noise, are sensitive to the context or underlying view of what is essentially a stochastic process. A framework ... -
Numerical modeling results for mode propagation in a wedge
(NATO. SACLANTCEN, 1987/11)A PE (parabolic equation) code is used to study propagation in a shallow water wedge with a penetrable bottom. Particular attention is given to "wedge modes" that have wave fronts that are arcs of circles centered on the ... -
Numerical modelling of acoustic scattering by smooth inclusions in a layered fluid-solid medium
(NATO. SACLANTCEN, 1997)A boundary integral equation (BIE) method as descnbed for computing the scattering of a monofrequent acoustic field by a smooth, rigid 30 object in a layered range-independent fluid-solid medium. The BIE is discretized ... -
Obtaining the ocean index of refraction spectrum from the acoustic amplitude fluctuations
(NATO. SACLANTCEN, 1997)The feasibility of using acoustic measurements to determine the properties of a shallow water internal wave field is investigated through numerical simulations. The random intemal wave field is modeled by a generalized ... -
Ocean-basin reverberation from large underwater explosions: part 1: source-level and propagation-loss modelling
(NATO. SACLANTCEN, 1975/10)Predicting the reverberant returns from ocean basin reflectors requires describing acoustic source levels for large, conventional underwater explosions, defining the two way propagation loss and signal spreading from the ... -
Ocean-basin reverberation from large underwater explosions: part 2: computer model for reverberation
(NATO. SACLANTCEN, 1975/10)Following detonation of an underwater explosion, sound reverberates from the ocean surface and bottom and from scatterers within the medium. In addition, the boundaries of the ocean basin and obstructions within it, such ... -
Ocean-bottom reflectivity (a point of view)
(NATO. SACLANTCEN, 1975/10)The analysis procedures for extracting bottom loss values from pulsed acoustic signals that have interacted with the ocean bottom do not inherently consider sub-bottom refraction and reflection of sound, which are important ... -
Passive localization using propagation models
(NATO. SACLANTCEN, 1987/06)Passive ranging using propagation models can be effected in two different ways: forward modeling -
PC-based propagation and sonar prediction models
(NATO. SACLANTCEN, 1995/12)Six acoustic models available for use on PC's are tested on a series of typical propagation situations from the North Atlantic and the Mediterranean. The model set includes both early US Navy models (ASTRAL, FACT, RAYMODE) ... -
Performance assessment of propagation models in AESS-6.0
(NATO. SACLANTCEN, 1999/08)A set of AESS propagation-loss predictions has been generated for typical operational scenarios in both deep and shallow water, for two sonar frequencies (500 and 3500 Hz) and for several source-receiver combinations. ... -
Performance assessment of the LYBIN - 2.0 propagation-loss model
(NATO. SACLANTCEN, 2001/07)A new acoustic model LYBIN has been proposed for inclusion in the AESS model set. In order to determine this model's prediction accuracy and computational efficiency, SACLANTCEN was tasked to test LYBIN on exactly the same ...