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Article
The Influence of Bottom Sediment on the Propagation of Caustic Beams in Oceanic Waveguides
Abstract—Numerical modeling with the use of mode theory was used to investigate the regularities of the spatial (depth and horizontal distance) distribution of the acoustic field intensity formed by multiple inte...
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Article
Influence of Bottom Irregularities on Caustic Beam Propagation in Oceanic Waveguides
Using the geometrical acoustics approximation and parabolic equation, we investigated the regularities in the spatial distribution of the acoustic field intensity generated by interaction between a caustic bea...
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Article
Caustic and Weakly Diverging Beams in Horizontally Inhomogeneous Oceanic Waveguides
Using approximate analytical calculations based on the WKB and adiabatic approximations for the mode representation of the field, as well as numerical simulation based on the theory of adiabatic modes, geometr...
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Article
Features of the Invariant of the Spatial–Frequency Interference Structure of Acoustic Fields in Oceanic Waveguides
The paper considers the regular patterns that can be manifested in the behavior of the invariant of the spatial–frequency interference structure of an acoustic field in oceanic waveguides that are homogeneous ...
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Article
Formation of a weakly diverging caustic beam in an underwater sound channel open to the bottom
The paper studies the patterns manifesting themselves in the formation and propagation of caustic and weakly diverging beams using the geometric acoustic approximation and mode theory applied to the simplest m...
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Article
Algorithms for converting 3D surface roughness spectra when calculating frequency-angle reverberation characteristics
On the basis of an earlier developed model of sound scattering by surface disturbances characterized by 3D roughness spectra, we propose and test a sufficiently fast algorithm for calculating the spectral powe...
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Article
The spatio-temporal structure of wideband acoustic pulses in shallow sea
We study the influence of a bottom-sediment layer on the spatio-temporal structure of wideband acoustic pulses in shallow sea. The shallow sea is modeled as a uniform liquid layer above a layer of liquid sedim...
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Article
Manifestation of weakly diverging beams of rays in the spatiotemporal structure of the acoustic signal field in oceanic waveguides
It is established that the existence of weakly divergent beams in an oceanic waveguides leads, in a certain time interval and depth range, to the formation of a characteristic triplet structure of wavefronts. ...
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Article
Estimation of surface roughness effect on spectral characteristics of tone signals propagating along stationary paths in a shallow sea
Scattering of a tonal low-frequency (up to 400 Hz) acoustic signal on a rough surface during its propagation along stationary paths in a shallow water area is considered. A calculation technique of estimating ...
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Article
Estimation of space-time characteristics of surface roughness based on video images
The technique of operative measurements of wind-induced wave characteristics based on video imaging of the sea surface and simultaneously measuring the current spectra of wind waves using an anchored buoy is p...
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Article
Azimuthal dependence of reverberation from a harmonic signal propagating in shallow water
The problem of scattering from a rough sea surface is considered for a harmonic low-frequency (200–400 Hz) acoustic signal propagating in a shallow water area. An experimental study of the azimuthal reverberat...
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Article
Characteristics of the reverberation signal at a vertical array with tonal insonification of a shallow-water basin
The angular and spectral characteristics of reverberation signals on a fixed path are studied by using vertical receiving arrays with a tonal insonification of the basin. The choice of the frequency range F ∼ 200...
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Article
Phase conjugation in an acoustic waveguide
A method for holographic observation of sound sources and passive inhomogeneities in acoustic waveguides is proposed. The method is based on the principle of coherent phase conjugation. A possibility of visual...
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Article
Caustics and weakly divergent beams in oceanic waveguides
It is found that the weakly divergent beam formed around the reference ray with minimal cycle length does not stand out in intensity against the background of the total field. It is shown that, under the same ...
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Article
Effect of the sound velocity stratification in the bottom sediment layer on the diffraction focusing of an acoustic field in a shallow sea
It is shown that an increase in the sound velocity gradient in the bottom sediment layer results in the formation of additional zones of diffraction focusing of the acoustic field generated by a vertical line ...
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Article
Effect of the sediment layer on the diffraction focusing of an acoustic field in a shallow sea
Features characterizing the formation of the spatial (in depth and horizontal distance) interference structure of an acoustic field generated by a point tone source or a vertically distributed tone source in a...
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Article
Specific features of the space-time structure of acoustic signals in multimode waveguides
The effect of the diffraction focusing of an acoustic field on the space-time intensity distribution of narrow-band pulsed signals in multimode oceanic waveguides is analytically and numerically studied. The l...
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Article
Space-Frequency Interference Structure of Acoustic Fields in Oceanic Waveguides
Laws manifesting themselves in the formation of the space-frequency distribution of the intensity of the acoustic field generated by a point source of wide-band radiation are considered. Most attention is conc...
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Article
Effect of the sediment layer on the excitation of acoustic modes and lateral waves in shallow sea
The simplest model of a shallow sea in the form of an isovelocity water layer and a fluid sediment layer overlying a homogeneous elastic halfspace is used to investigate the effect of the thickness of the sedi...
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Chapter
Multi-View Imaging in Oceanic Waveguides by Dark Field Method
A full understanding of the problem of visualization the acoustic sources (“an acousticvision” )1,2, i.e. forming the spatial signal intensity distribution pattern, is fundamental to most developments in a large ...
