The waveguide invariant for a Pekeris waveguide

2021 ◽  
Vol 150 (4) ◽  
pp. A282-A282
Author(s):  
Heechun Song ◽  
Gihoon Byun
Keyword(s):  
Waveguide Invariant ◽  
Pekeris Waveguide

Dedispersion Transform Method for Extracting the Normal Modes of a Shallow Water Acoustic Signal in the Pekeris Waveguide

2015 ◽  
Vol 40 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Guang-Bing Yang ◽  
Lian-Gang Lü ◽  
Da-Zhi Gao ◽  
Ying Jiang ◽  
Hong-Ning Liu
Keyword(s):  
Normal Mode ◽  
Extraction Method ◽  
Dispersion Compensation ◽  
Normal Modes ◽  
Transform Method ◽  
Swarm Optimization ◽  
Waveguide Invariant ◽  
Source Signal ◽  
Pekeris Waveguide ◽  
Mode Extraction

Abstract The normal modes cannot be extracted even in the Pekeris waveguide when the source-receiver distance is very close. This paper introduces a normal mode extraction method based on a dedispersion transform (DDT) to solve this problem. The method presented here takes advantage of DDT, which is based on the waveguide invariant such that the dispersion associated with all of the normal modes is removed at the same time. After performing DDT on a signal received in the Pekeris waveguide, the waveform of resulting normal modes is very close to the source signal, each with different position and amplitude. Each normal mode can be extracted by determining its position and amplitude parameters by applying particle swarm optimization (PSO). The waveform of the extracted normal mode is simply the waveform of the source signal; the real waveform of the received normal mode can then be recovered by applying dispersion compensation to the source signal. The method presented needs only one receiver and is verified with experimental data

scholarly journals A Green’s Function for Acoustic Problems in Pekeris Waveguide Using a Rigorous Image Source Method

2021 ◽  
Vol 11 (6) ◽  
pp. 2722
Author(s):  
Zhiwen Qian ◽  
Dejiang Shang ◽  
Yuan Hu ◽  
Xinyang Xu ◽  
Haihan Zhao ◽  
...  
Keyword(s):  
Green’S Function ◽  
Shallow Water ◽  
Green's Function ◽  
Plane Waves ◽  
Spherical Wave ◽  
Sound Field ◽  
Efficient Computation ◽  
Image Source ◽  
Source Method ◽  
Pekeris Waveguide

The Green’s function (GF) directly eases the efficient computation for acoustic radiation problems in shallow water with the use of the Helmholtz integral equation. The difficulty in solving the GF in shallow water lies in the need to consider the boundary effects. In this paper, a rigorous theoretical model of interactions between the spherical wave and the liquid boundary is established by Fourier transform. The accurate and adaptive GF for the acoustic problems in the Pekeris waveguide with lossy seabed is derived, which is based on the image source method (ISM) and wave acoustics. First, the spherical wave is decomposed into plane waves in different incident angles. Second, each plane wave is multiplied by the corresponding reflection coefficient to obtain the reflected sound field, and the field is superposed to obtain the reflected sound field of the spherical wave. Then, the sound field of all image sources and the physical source are summed to obtain the GF in the Pekeris waveguide. The results computed by this method are compared with the standard wavenumber integration method, which verifies the accuracy of the GF for the near- and far-field acoustic problems. The influence of seabed attenuation on modal interference patterns is analyzed.

Experimental study on waveguide invariant passive ranging based on buoy

2021 ◽  
Author(s):  
Zhizhuan Wang ◽  
Mingwei Zhang ◽  
Yang Zhang ◽  
Guijuan Li ◽  
Xuegang Zhang
Keyword(s):  
Experimental Study ◽  
Waveguide Invariant ◽  
Passive Ranging

Focusing Green's function using the waveguide invariant theory

2021 ◽  
Vol 150 (4) ◽  
pp. A281-A281
Author(s):  
Daehwan Kim ◽  
Donghyeon Kim ◽  
J. S. Kim
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Invariant Theory ◽  
Waveguide Invariant

scholarly journals Measured depth-dependence of waveguide invariant in shallow water with a summer profile

2016 ◽  
Vol 139 (6) ◽  
pp. EL184-EL189 ◽  
Author(s):  
Altan Turgut ◽  
Laurie T. Fialkowski ◽  
Jeffrey A. Schindall
Keyword(s):  
Shallow Water ◽  
Depth Dependence ◽  
Waveguide Invariant
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