Evaluation of Improvements to an Underwater Acoustic Propagation Model Based on the Parabolic Equation PDF Download
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Author: Kirk A. Weatherly
Publisher:
ISBN: 9781423536963
Category :
Languages : en
Pages : 96
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Book Description
This thesis examines two implementations of the parabolic equation approximation to the acoustic wave equation aimed at removing three errors inherent to the wide-angle parabolic equation (WAPE) model. First, the selection of the range step size used by the split-step Fourier algorithm affects the convergence of the solution. Second, in certain ocean environments WAPE incorrectly computes the down-range transmission loss. Finally, WAPE does not reproduce the standard normal mode basis set as defined by normal mode theory. A double-precision implementation of the WAPE (DP-WAPE) is developed to evaluate the dependence of solution convergence on the numerical precision of the model. Finally, an implementation that is insensitive to the choice of the reference sound speed (COIPE) is evaluated for its ability to reduce or remove the latter two of these three errors. The stability other WAPE solution was found to be unaffected by the DP-WAPE implementation. The range-step dependence is inherent to the split-step algorithm. The COIPE corrects the transmission loss anomaly and satisfactorily reproduces the standard normal mode basis set.
Author: Kirk A. Weatherly
Publisher:
ISBN: 9781423536963
Category :
Languages : en
Pages : 96
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Book Description
This thesis examines two implementations of the parabolic equation approximation to the acoustic wave equation aimed at removing three errors inherent to the wide-angle parabolic equation (WAPE) model. First, the selection of the range step size used by the split-step Fourier algorithm affects the convergence of the solution. Second, in certain ocean environments WAPE incorrectly computes the down-range transmission loss. Finally, WAPE does not reproduce the standard normal mode basis set as defined by normal mode theory. A double-precision implementation of the WAPE (DP-WAPE) is developed to evaluate the dependence of solution convergence on the numerical precision of the model. Finally, an implementation that is insensitive to the choice of the reference sound speed (COIPE) is evaluated for its ability to reduce or remove the latter two of these three errors. The stability other WAPE solution was found to be unaffected by the DP-WAPE implementation. The range-step dependence is inherent to the split-step algorithm. The COIPE corrects the transmission loss anomaly and satisfactorily reproduces the standard normal mode basis set.
Author: Paul C. Etter
Publisher: CRC Press
ISBN: 1351831984
Category : Technology & Engineering
Languages : en
Pages : 557
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Book Description
Underwater Acoustic Modeling and Simulation, Fourth Edition continues to provide the most authoritative overview of currently available propagation, noise, reverberation, and sonar-performance models. This fourth edition of a bestseller discusses the fundamental processes involved in simulating the performance of underwater acoustic systems and emphasizes the importance of applying the proper modeling resources to simulate the behavior of sound in virtual ocean environments. New to the Fourth Edition Extensive new material that addresses recent advances in inverse techniques and marine-mammal protection Problem sets in each chapter Updated and expanded inventories of available models Designed for readers with an understanding of underwater acoustics but who are unfamiliar with the various aspects of modeling, the book includes sufficient mathematical derivations to demonstrate model formulations and provides guidelines for selecting and using the models. Examples of each type of model illustrate model formulations, model assumptions, and algorithm efficiency. Simulation case studies are also included to demonstrate practical applications. Providing a thorough source of information on modeling resources, this book examines the translation of our physical understanding of sound in the sea into mathematical models that simulate acoustic propagation, noise, and reverberation in the ocean. The text shows how these models are used to predict and diagnose the performance of complex sonar systems operating in the undersea environment.
Author: Yonghoon Ha
Publisher:
ISBN: 9781423531487
Category :
Languages : en
Pages : 81
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Book Description
The Monterey-Miami Parabolic Equation (MMPE) Model is a full-wave underwater acoustic propagation model that utilizes the split-step Fourier marching algorithm. Previously the MMPE model was implemented in Fortran language and ran with a simple command line interface either in a Unix or DOS command window. After the Fortran code was run, the resulting binary data output file was post-processed using Matlab routines to extract specific field data and present the results in graphical form. This approach requires the user to have installed both Matlab and Fortran compilers. The MMPE model and associated acoustic processing tools are now rewritten in the object-oriented language Java. This new version of the MMPE model built within a Windows framework is called WinMMPE. Integrating the model, the post-processing calculations and the graphics generation together with a graphic user interface has produced a more attractive tool for users. A user-friendly, efficient, and accurate full-wave acoustic propagation model with enhanced visualization can make it easier to assess the spatial transmission loss in the underwater acoustic environment.
Author: P.C. Etter
Publisher: CRC Press
ISBN: 9780419201908
Category : Architecture
Languages : en
Pages : 364
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Book Description
Underwater Acoustic Modeling provides the only comprehensive source on how to translate our physical understanding of sound in the sea into mathematical formulas solvable by computers.
Author: Finn Bruun Jensen
Publisher:
ISBN:
Category : Computer simulation
Languages : en
Pages : 68
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Book Description
Two papers given at the NATO Advanced Research Workshop on Hybrid Formulation of Wave Propagation and Scattering on 30 Aug. to 3 Sept. 1983 are published as a review of SACLANTCEN's recent programme in underwater-acoustic modelling. The first briefly reviews the physics of sound propagation in the ocean. In it the mathematical foundations of the most widely used acoustic models (ray, mode, fast field, parabolic equation) are presented and the areas of applicability of the various models are indicated. A few numerical examples are included to show the consistency among the different computer models in overlapping regimes of validity. A series of computational examples is given to demonstrate the applicability of these models to a wide range of general wave-propagation problems. The second paper presents a new numerical model, of the fast field type, where the depth-separated wave equation is solved by a numerical technique very similar to that used in finite-element programs. The speed improvement over existing models of the same type is considerable, especially in cases with many sources and receivers. The model has been used for studying both seismic pulse propagation in shallow water and reflection of pulsed ultrasonic beams from a fluid/solid interface.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Book Description
Proper characterization of underwater acoustic transmission loss (TL) relies on proper treatment of the air/water and water/sediment interfaces. This paper will focus on how the air/water interface is treated in parabolic equation (PE) models such as the range dependent acoustic model (RAM) [Collins, M.D., "Applications and time-domain solution of higher-order parabolic equations in underwater acoustics," J. Acoust. Soc. Am., 86 (3), 1097-1102, 1989] and the finite element parabolic equation (FEPE) model [Collins, M.D., "A higher-order parabolic equation for wave propagation in an ocean overlying an elastic bottom", J. Acoust. Soc. Am. 86, 1459-1464, 1989]. Two surface loss methods have been implemented in RAM, a surface loss versus angle (LVA) and a conformal mapping (CM) method. Additionally, the CM method has been implemented in FEPE. These two methods are discussed and compared for realistic test cases and a third option, which has accuracy consistent with the CM but speed more aligned with the LVA approach is discussed.
Author: D. Lee
Publisher: Elsevier
ISBN: 1483295699
Category : Science
Languages : en
Pages : 134
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Book Description
A concise guide to the theory and application of numerical methods for predicting ocean acoustic propagation, also providing an introduction to numerical methods, with an overview of those methods presently in use. An in-depth development of the implicit-finite-difference technique is presented together with bench-mark test examples included to demonstrate its application to realistic ocean environments. Other applications include atmospheric acoustics, plasma physics, quantum mechanics, optics and seismology.
Author:
Publisher:
ISBN:
Category : United States
Languages : en
Pages :
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Book Description
Author: Joseph Bishop Keller
Publisher: Springer
ISBN:
Category : Science
Languages : en
Pages : 314
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Book Description
Author: Ding Lee
Publisher: World Scientific
ISBN: 9789810223038
Category : Science
Languages : en
Pages : 224
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Book Description
This book introduces a comprehensive mathematical formulation of the three-dimensional ocean acoustic propagation problem by means of functional and operator splitting techniques in conjunction with rational function approximations. It presents various numerical solutions of the model equation such as finite difference, alternating direction and preconditioning. The detailed analysis of the concept of 3D, N x 2D and 2D problems is very useful not only mathematically and physically, but also computationally. The inclusion of a complete detailed listing of proven computer codes which have been in use by a number of universities and research organizations worldwide makes this book a valuable reference source. Advanced knowledge of numerical methods, applied mathematics and ocean acoustics is not required to understand this book. It is oriented toward graduate students and research scientists to use for research and application purposes.
