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Geometric and boundary element metho...

The University of Nebraska - Lincoln., Architectural Engineering.

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Geometric and boundary element method simulations of acoustic reflections from rough, finite, or non-planar surfaces.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Geometric and boundary element method simulations of acoustic reflections from rough, finite, or non-planar surfaces./
Author:	Rathsam, Jonathan.
Description:	176 p.
Notes:	Adviser: Lily M. Wang.
Contained By:	Dissertation Abstracts International69-03B.
Subject:	Architecture. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3297864
ISBN:	9780549491767

Geometric and boundary element method simulations of acoustic reflections from rough, finite, or non-planar surfaces.
Rathsam, Jonathan.

Geometric and boundary element method simulations of acoustic reflections from rough, finite, or non-planar surfaces. - 176 p.

Adviser: Lily M. Wang.

Thesis (Ph.D.)--The University of Nebraska - Lincoln, 2008.

This dissertation seeks to advance the current state of computer-based sound field simulations for room acoustics. The first part of the dissertation assesses the reliability of geometric sound-field simulations, which are approximate in nature. The second part of the dissertation uses the rigorous boundary element method (BEM) to learn more about reflections from finite reflectors: planar and non-planar.

ISBN: 9780549491767Subjects--Topical Terms:

523581
Architecture.

Geometric and boundary element method simulations of acoustic reflections from rough, finite, or non-planar surfaces.
LDR:03543nmm 2200349 a 45 001 885987
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020 $a 9780549491767
035 $a (UMI)AAI3297864
035 $a AAI3297864
040 $a UMI $c UMI
100 1 $a Rathsam, Jonathan. $3 1057651
245 1 0 $a Geometric and boundary element method simulations of acoustic reflections from rough, finite, or non-planar surfaces.
300 $a 176 p.
500 $a Adviser: Lily M. Wang.
500 $a Source: Dissertation Abstracts International, Volume: 69-03, Section: B, page: 1693.
502 $a Thesis (Ph.D.)--The University of Nebraska - Lincoln, 2008.
520 $a This dissertation seeks to advance the current state of computer-based sound field simulations for room acoustics. The first part of the dissertation assesses the reliability of geometric sound-field simulations, which are approximate in nature. The second part of the dissertation uses the rigorous boundary element method (BEM) to learn more about reflections from finite reflectors: planar and non-planar.
520 $a Acoustical designers commonly use geometric simulations to predict sound fields quickly. Geometric simulation of reflections from rough surfaces is still under refinement. The first project in this dissertation investigates the scattering coefficient, which quantifies the degree of diffuse reflection from rough surfaces. The main result is that predicted reverberation time varies inversely with scattering coefficient if the sound field is nondiffuse. Additional results include a flow chart that enables acoustical designers to gauge how sensitive predicted results are to their choice of scattering coefficient.
520 $a Geometric acoustics is a high-frequency approximation to wave acoustics. At low frequencies, more pronounced wave phenomena cause deviations between real-world values and geometric predictions. Acoustical designers encounter the limits of geometric acoustics in particular when simulating the low frequency response from finite suspended reflector panels. This dissertation uses the rigorous BEM to develop an improved low-frequency radiation model for smooth, finite reflectors. The improved low frequency model is suggested in two forms for implementation in geometric models.
520 $a Although BEM simulations require more computation time than geometric simulations, BEM results are highly accurate. The final section of this dissertation uses the BEM to investigate the sound field around non-planar reflectors. The author has added convex edges rounded away from the source side of finite, smooth reflectors to minimize coloration of reflections caused by interference from boundary waves. Although the coloration could not be fully eliminated, the convex edge increases the sound energy reflected into previously nonspecular zones. This excess reflected energy is marginally audible using a standard of 20 dB below direct sound energy. The convex-edged panel is recommended for use when designers want to extend reflected energy spatially beyond the specular reflection zone of a planar panel.
590 $a School code: 0138.
650 4 $a Architecture. $3 523581
650 4 $a Physics, Acoustics. $3 1019086
690 $a 0729
690 $a 0986
710 2 $a The University of Nebraska - Lincoln. $b Architectural Engineering. $3 1057650
773 0 $t Dissertation Abstracts International $g 69-03B.
790 $a 0138
790 1 0 $a Barton, John P. $e committee member
790 1 0 $a Erdogmus, Ece $e committee member
790 1 0 $a Houser, Kevin W. $e committee member
790 1 0 $a Wang, Lily M., $e advisor
791 $a Ph.D.
792 $a 2008
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3297864