ISSN:0001-4966    

DOI:10.1121/1.414847

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414824

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414827

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414828

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414882

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

The purpose of these acoustical patent reviews is to provide enough information for a Journal reader to decide whether to seek more information from the patent itself. Any opinions expressed here are those of the reviewers as individuals and are not legal opinions. Printed copies of United States Patents may be ordered at $3.00 each from the Commissioner of Patents and Trademarks, Washington, DC 20231. Patents are available via the Internet athttp://www.uspto.gov.

ISSN:0001-4966    

DOI:10.1121/1.414829

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

This study examines the known acoustical attributes of concert halls and depicts the ways in which they interrelate with the music performed in them. The first section distinguishes between direct sound, early sound, and reverberant sound. The second section concerns how musical factors and acoustical attributes affect vertical and horizontal definition of the music. Figures illustrate the ways that the sounds of fast and slow music are altered by different acoustical conditions. The final section discusses the important acoustical attributes, intimacy, spaciousness, timbre, and tone color.

ISSN:0001-4966    

DOI:10.1121/1.414808

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

Porous media are anisotropic due to bedding, compaction, and the presence of aligned microcracks and fractures. Here, it is assumed that the skeleton (and not the solid itself) is anisotropic. The rheological model also includes anisotropic tortuosity and permeability. The poroelastic equations are based on a transversely isotropic extension of Biot’s theory, and the problem is of plane strain type, i.e., two dimensional, describingqP−qSpropagation. In the high‐frequency case, the (two) viscodynamic operators are approximated by Zener relaxation functions that allow a closed differential formulation of Biot’s equation of motion. A plane‐wave analysis derives expressions for the slowness, attenuation, and energy velocity vectors, and quality factor for homogeneous viscoelastic waves. The slow wave shows an anomalous polarization behavior. In particular, when the medium is strongly anisotropic the polarization is quasishear and the wave presents cuspidal triangles. Anisotropic tortuosity affects mainly the slow wavefront, and anisotropic permeability produces strong anisotropic attenuation of the three modes. The diffusive characteristics of the slow mode are predicted by the plane‐wave analysis. As in the single‐phase case, it is confirmed that the phase velocity is the projection of the energy velocity vector onto the propagation direction. Moreover, some fundamental energy relations, valid for a single‐phase medium, are generalized to two‐phase media. Transient propagation is solved with a direct grid method and a time‐splitting integration algorithm, allowing the solution of the stiff part of the differential equations in closed analytical form. The snapshots show that the three waves are propagative when the fluid is ideal (zero viscosity). It is confirmed that, when the fluid is viscous, the slow wave becomes diffusive and appears as a static mode at the source location. The modeling confirms the triplication (cusps) of the slow wave and the polarization behavior predicted by the plane analysis.

ISSN:0001-4966    

DOI:10.1121/1.414809

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

Weighted residual methods are frequently used for solving a variety of problems in electromagnetics, solid mechanics, weather prediction, and fluid mechanics. Amidst these weighted residual methods, the electromagnetics research community frequently uses a technique known as the method of moments (MM). MM can be used to systematically form the whole set of expansion functions needed to construct the approximate solution of the problem based on one given basis function. This property of the method of moments can be exploited to solve acoustic field equations in irregular domains. The method of moments with finite difference operator approximation is explored in this paper. As illustrations of the applications of this method, both one‐ and two‐dimensional acoustic problems are solved in this paper. These applications help to highlight the potential of the method of moments.

ISSN:0001-4966    

DOI:10.1121/1.414810

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

A new and effective analytical perturbation method is presented for the multipole acoustic logging in a transversely isotropic elastic solid whose symmetric principal axis is perpendicular to the borehole axis. The transversely isotropic elastic solid is regarded as a relevant isotropic elastic solid added to the perturbations, and three perturbation quantities about moduli deviated from the isotropic medium are introduced. By selecting a group of displacement potentials and a cylindrical coordinate system oriented along the borehole axis, the zero‐ and first‐order perturbation solutions of the multipole acoustic field are derived for the weak transversely isotropic elastic solid which has its symmetric principal axis perpendicular to the borehole axis. The acoustic fields inside and outside the borehole excited by a multipole source are investigated. It is found that not only thenth multipole acoustic field can be excited by annth multipole source, but the multipole fields whose orders are higher and lower thannalso can be excited by annth multipole source.

ISSN:0001-4966    

DOI:10.1121/1.414855

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP