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Low Frequency Sound Propagation Modeling Over A Locally Reacting Boundary Using The Parabolic Approximation
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Book Synopsis Low-Frequency Sound Propagation Modeling Over a Locally-Reacting Boundary Using the Parabolic Approximation by : National Aeronautics and Space Adm Nasa
Download or read book Low-Frequency Sound Propagation Modeling Over a Locally-Reacting Boundary Using the Parabolic Approximation written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-21 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is substantial interest in the analytical and numerical modeling of low-frequency, long-range atmospheric acoustic propagation. Ray-based models, because of frequency limitations, do not always give an adequate prediction of quantities such as sound pressure or intensity levels. However, the parabolic approximation method, widely used in ocean acoustics, and often more accurate than ray models for lower frequencies of interest, can be applied to acoustic propagation in the atmosphere. Modifications of an existing implicit finite-difference implementation for computing solutions to the parabolic approximation are discussed. A locally-reacting boundary is used together with a one-parameter impedance model. Intensity calculations are performed for a number of flow resistivity values in both quiescent and windy atmospheres. Variations in the value of this parameter are shown to have substantial effects on the spatial variation of the acoustic signal. Robertson, J. S. and Siegman, W. L. and Jacobson, M. J. Unspecified Center NAG1-929...
Book Synopsis Low-frequency Sound Propagation Modeling Over a Locally-reacting Boundary Using the Parabolic Approximation by : J. S. Robertson
Download or read book Low-frequency Sound Propagation Modeling Over a Locally-reacting Boundary Using the Parabolic Approximation written by J. S. Robertson and published by . This book was released on 1989 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Book Synopsis Computational Atmospheric Acoustics by : E.M. Salomons
Download or read book Computational Atmospheric Acoustics written by E.M. Salomons and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 331 pages. Available in PDF, EPUB and Kindle. Book excerpt: Noise from cars, trains, and aeroplanes can be heard at large distances from the source. Accurate predictions of the loudness of the noise require accurate computations of sound propagation in the atmosphere. This book describes models that can be used for these computations. The models take into account complex effects of the atmosphere and the ground surface on sound waves, including the effects of wind and temperature distributions, atmospheric turbulence, irregular terrain, and noise barriers. The main text of the book focuses on physical effects in atmospheric acoustics. The effects are illustrated by many numerical examples. The main text requires a very limited mathematical background from the reader; detailed mathematical descriptions of the models, developed from the basic principles of acoustics, are presented in appendices. Models for moving media are compared with models that are based on the effective sound speed approach. Both two-dimensional models and three-dimensional models are presented. As meteorological effects play an important role in atmospheric acoustics, selected topics from boundary layer meteorology and the theory of turbulence are also presented.
Book Synopsis Theoretical And Computational Acoustics - Proceedings Of The International Conference (In 2 Volumes) by : John E Ffowcs Williams
Download or read book Theoretical And Computational Acoustics - Proceedings Of The International Conference (In 2 Volumes) written by John E Ffowcs Williams and published by World Scientific. This book was released on 1994-10-25 with total page 1028 pages. Available in PDF, EPUB and Kindle. Book excerpt: This conference provided a forum for active researchers to discuss the state of the art in theoretical and computational acoustics. Topics covered structural acoustics, scattering, 3-dimensional propagational problems, fluid/elastic interfaces, wavelets and their impact on acoustics, computational methods and supercomputing.
Book Synopsis Theoretical And Computational Acoustics 2003 by : Alexandra Tolstoy
Download or read book Theoretical And Computational Acoustics 2003 written by Alexandra Tolstoy and published by World Scientific. This book was released on 2004-08-24 with total page 493 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ICTCA conference provides an interdisciplinary forum for active researchers in academia and industry who are of varying backgrounds to discuss the state-of-the-art developments and results in theoretical and computational acoustics and related topics. The papers presented at the meeting cover acoustical problems of common interest across disciplines and their accurate mathematical and numerical modeling.This volume collects papers that were presented at the sixth meeting. The subjects include geophysics, scattering and diffraction, the parabolic equation (with special sessions in honor of Dr Fred Tappert), seismic exploration, boundary element methods, visualization, oil industry applications, shallow water acoustics, matched field tracking, bubbles, waves in complex media, seabed interactions, ocean acoustic inversion, and mathematical issues in underwater acoustics.
Book Synopsis The Propagation of Low Frequency Sound Through an Audience by : Elena Shabalina
Download or read book The Propagation of Low Frequency Sound Through an Audience written by Elena Shabalina and published by Logos Verlag Berlin GmbH. This book was released on 2014 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: At large outdoor concerts or festivals subwoofers, the dedicated low frequency loudspeakers, are often placed in a row in front of the stage as an evenly spaced array in order to control the directivity of sound at low frequencies. The audience itself often stands tightly packed in front of the array, so that sound waves propagate partly through the audience and partly over it. This thesis presents an investigation on how exactly the presence of the audience influences the propagation of sound. A mathematical model of an audience as an equivalent fluid is constructed with the help of the porous medium theory. The equivalent fluid parameters, such as the wave impedance, the speed of sound and the reflection coefficient from the audience/air boundary, are calculated both for a constant and a variable concentration of an audience. The model is verified by a Boundary Element Method simulation, scale measurements and live concert measurements. A new live measurement method is developed to evaluate the low frequency sound pressure level distribution without disturbing the ongoing event. The study reaches the conclusion that at low frequencies an audience forms a medium with the impedance significantly different from the impedance of the air, which leads to the reflection of sound waves from the boundaries back into the audience and increase of the sound pressure level as well as interference effects. Possible applications of the findings are mainly sound system design and event planning.
Book Synopsis The Journal of the Acoustical Society of America by :
Download or read book The Journal of the Acoustical Society of America written by and published by . This book was released on 2009 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Springer Handbook of Acoustics by : Thomas Rossing
Download or read book Springer Handbook of Acoustics written by Thomas Rossing and published by Springer Science & Business Media. This book was released on 2007-06-21 with total page 1179 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is an unparalleled modern handbook reflecting the richly interdisciplinary nature of acoustics edited by an acknowledged master in the field. The handbook reviews the most important areas of the subject, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest research and applications are incorporated throughout, including computer recognition and synthesis of speech, physiological acoustics, diagnostic imaging and therapeutic applications and acoustical oceanography. An accompanying CD-ROM contains audio and video files.
Book Synopsis Meteorological and Geoastrophysical Abstracts by :
Download or read book Meteorological and Geoastrophysical Abstracts written by and published by . This book was released on 1995 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering the world's literature on meteorology, climatology, atmospheric chemistry and physics, physical oceanography, hydrology, glaciology, and related environmental sciences.
Book Synopsis Government Reports Annual Index by :
Download or read book Government Reports Annual Index written by and published by . This book was released on 1989 with total page 1708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Proceedings of the ... International Congress on Acoustics by :
Download or read book Proceedings of the ... International Congress on Acoustics written by and published by . This book was released on 1992 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Proceedings by : International Congress on Acoustics
Download or read book Proceedings written by International Congress on Acoustics and published by . This book was released on 1992 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Theoretical Models to Investigate Sound Propagation Over Irregular Terrain by : Santosh Parakkal
Download or read book Theoretical Models to Investigate Sound Propagation Over Irregular Terrain written by Santosh Parakkal and published by . This book was released on 2010 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this work is to establish an accurate and practical numerical method to determine the acoustic field at any point on the Earth's surface in the presence of range-dependent (atmosphere and terrain) conditions. In the sound propagation over irregular terrain, the approach is to map the terrain coordinates in to a flat or smooth earth coordinate system. This results in a modified parabolic equation (PE) which is subjected to modified surface boundary conditions. The Beilis and Tappert PE method is studied in applications of sound propagation over irregular terrain. The correct ground impedance boundary condition for porous ground is derived and applied to the propagation predictions over hills with different slope angles. The Generalized Polar Coordinate parabolic equation method (Polar-PE method) was developed partly to provide a very solid numerical benchmark to the Beilis and Tappert PE method. The Polar-PE method makes it possible to compute sound propagation over arbitrary large-scale terrain where the local radii of curvature are large compared to the acoustic wavelength. Both approaches are outlined and a comparison is made of the accuracy and computational demands of the methods. Also, the theoretical predictions from the two methods are compared to acoustic field measurements.
Book Synopsis Archives of Acoustics Quarterly by :
Download or read book Archives of Acoustics Quarterly written by and published by . This book was released on 2012 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Congress Reports written by and published by . This book was released on 1992 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt:
