1 edition of Parabolic Equation Modeling of Bottom Interface and Volume Reverberation in Shallow Water found in the catalog.
Parabolic Equation Modeling of Bottom Interface and Volume Reverberation in Shallow Water
by Storming Media
Written in English
|The Physical Object|
The shallow water equations are a set of hyperbolic partial differential equations (or parabolic if viscous shear is considered) that describe the flow below a pressure surface in a fluid (sometimes, but not necessarily, a free surface).The shallow water equations in unidirectional form are also called Saint-Venant equations, after Adhémar Jean Claude Barré de Saint-Venant (see the related. The parabolic-equation (PE) approximation, first introduced by Tappert (b), 9. Tappert, F. D. (b). “ Parabolic equation method in underwater acoustics,” J. Am. 55, S has been shown to be an effective numerical technique for modeling underwater sound propagation in the ocean. This technique transforms the Helmholtz wave equation into a one-way wave equation that can Cited by:
Sea-Bottom Reverberation: The Role of Volume Inhomogeneities of the Sediment. M. Gensane. Reverberation Modeling with the Two-Way Parabolic Equation. M. D. Collins, G. J. Orris, W. A. Kuperman More recently this interest has been extended to very high frequencies in shallow water. Reverberation often limits the detection performance of. In this paper, a two-way parabolic equation (PE) method is developed for modeling rough interface reverberation. The model is employed to estimate the reverberation envelope probability density function from bottom roughness with Gaussian and exponential height distributions.
A good homogeneous, anisotropic bottom rough surface spectral model that is used in shallow water is the so-called “Goff–Jordan” model. If one combines the input parameters to this spectrum with the water and sediment sound speeds and densities near the water–sediment interface, the basic scattering problem is posed and can in theory Cited by: Abstract. The three-dimensional acoustic reverberation from bottom facets in a stratified, seismo-acoustic ocean environment is modeled using a hybrid approach where the environment is divided into two regions, one being a stratified model of the environment outside the scatterer, and the other being the scattering facet by: 1.
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THE REVERBERATION PROBLEM - SHALLOW WATER REVERBERATION AND SCATTERING THEORY 5. BOTTOM INTERFACE SCATTERING 5 1. Forward Propagation 10 2. Backward Propagation 10 3. Forcing Function 11 4. Statistical Treatment of the Scattered Field 14 5. Mean Squared Reverberation Pressure Level, RPL 19 B.
VOLUME SCATTERING 21 C. TIME-DOMAIN. Parabolic Equation Modeling of Bottom Interface and Volume Reverberation in Shallow Water Article September with 7 Reads How we measure 'reads'. Environmental Influence on Shallow Water Bottom Reverberation [Lee Boon Chuan] on *FREE* shipping on qualifying offers.
This is a NAVAL POSTGRADUATE SCHOOL MONTEREY CA report procured by the Pentagon and made available for public release. It has been reproduced in the best form available to the Pentagon.
It is not spiral-bound. A reverberation model based on the parabolic approximation is developed that includes sediment interface and volume perturbations. A multiple forward/single. A reverberation model based on the parabolic approximation is developed that includes sediment interface and volume perturbations.
A multiple forward/single backscatter approximation is made, and the structure of the solution is found to depend on the two-way propagation with a scattering strength scaling dependent on the local properties of the : Lit Siew.
A numerical implementation of the multiple forward, single backscattering approximation [F. Tappert, The Parabolic Approximation Method (Springer‐Verlag, New York, )] has been used to solve the parabolic wave equation for the prediction of bottom reverberation levels. Bathymetry for selected sites in the Mediterranean Sea is extracted from standard ocean databases and various Cited by: 1.
Reverberation Modelling using a Parabolic Equation Method Mr. Craig A. Hamm Dr. Gary H. Brooke volume and bottom reverberation Clutter is one of the most important effects affecting sonar performance in shallow water. Reverberation and target echo models are giving consistent results for flat bottom by: 1.
In this work, the influences of various environmental scenarios on the bottom interface and volume reverberation in shallow water were numerically analyzed. Based on similar modeling reverberation geometry defined in previous works, the numerical analyses were conducted for broadband pulse signals to generate complex reverberation structures in.
The principle of the PE method is to approximate the Helmholtz wave equation of elliptic type to a one-way wave equation of parabolic type by first factorizing the Helmholtz operator to forward and backward propagation components of square-root power and then neglecting the backward component for backscattering (Hardin and Tappert Hardin, R.
H., and Tappert, F. The mild-slope equation is exact for deep water and for water of constant nite depth (when it reduces to (3)). For shallow water (kh!0), it reduces to the shallow-water equation (formally, replace p(x) by h(x) in (7)). Finally, it is known that the mild-slope equation is valid for intermediate depths, provided h(x) does not change too rapidly.
Ocean reverberation is an important issue in underwater acoustics due to the significant influence on working performance of the active sonars. In this paper, a uniform bottom-reverberation model is proposed based on ray theory, which can calculate monostatic and bistatic reverberation intensity and explain the generation process of deep-water : Longhao Wang, Jixing Qin, Zhenglin Li, Jianjun Liu.
In this work, the influences of various environmental scenarios on the bottom interface and volume reverberation in shallow water were numerically : Boon Chuan. Lee. Abstract. Approved for public release; distribution in this thesis, the Monterey-Miami Parabolic Equation (MMPE) model is used to generate predictions from numerical analysis of the reverberation loss structure and peak vertical correlation structure generated by the water/bottom interface, the bottom/sub-bottom interface, and the bottom volume for a shallow water : Robert M.
Hill. Finite Differences: Parabolic Problems B. Khoo Lecture 5. SMA-HPC © NUS Outline • Governing Equation • Stability Analysis • 3 Examples • Relationship between σand λh • Implicit Time-Marching Scheme • Summary 2. SMA-HPC © NUS [2 2 0, u x t υ π ∂ = ∂ ∂x Governing Equation 3 Consider the Parabolic PDE in 1-D.
Abstract. The two-way parabolic equation and separation of variables are applied to develop an efficient method for solving acoustic reverberation problems involving a point source in an ocean that varies with both depth and one of the horizontal Cartesian by: 1.
The reverberation model used is based on the well-documented Parabolic Equation (PE) approximation. The environmental scenarios are divided into three main categories. They include different sound speed profiles, different levels of bottom interface roughness and different bottom volume : Boon Chuan.
Lee. Abstract In this thesis, the Monterey-Miami Parabolic Equation (MMPE) model is used to generate predictions from numerical analysis of the reverberation loss structure and peak vertical correlation.
It is also shown that the reverberation from a sub-bottom horizon is typically governed by higher grazing angles than the case where the scattering occurs at the water–sediment interface. There was generally very close agreement between the models as a function of frequency (– Hz), layer thickness (0–8 m), and range (1–15 km).Cited by: Abstract: In this paper, a two-way parabolic equation (PE) method is developed for modeling rough interface reverberation.
The model is employed to estimate the reverberation envelope probability density function from bottom roughness with Gaussian and exponential height by: In this thesis, the Monterey-Miami Parabolic Equation (MMPE) model is used to generate predictions from numerical analysis of the reverberation loss structure and peak vertical correlation Author: Han Kao.
A finite element model for the reverberation and propagation in a shallow water waveguide with a sandy bottom was calculated for five different environments at a center frequency of Hz. The various environments included a rough water/sediment interface, a rough air/water interface, roughness at both interfaces and downward and upward refracting sound speed profiles Cited by: type of reverberation predicted (water/bottom interface, bottom/subbottom interface, and bottom volume) as the roughness of the interfaces is varied.
These results indicate that, while typically the volume reverberation exhibits a more diffuse signal with noticeably less vertical coherence, an increase in interface roughness can cause the.In this paper, a two-way parabolic equation (PE) method is developed for modeling rough interface reverberation.
The model is employed to estimate the reverberation envelope probability density.