ISSN:0001-4966    

DOI:10.1121/1.414665

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414669

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414567

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414569

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:10.1121/1.414570

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

Rudimentary acoustical measurements performed inside six diverse ancient structures revealed that each sustained a strong resonance at a frequency between 95 and 120 Hz, despite major differences in chamber shapes and sizes. The resonant modal patterns all featured strong antinodes at the outer walls, with appropriately configured nodes and antinodes interspersed toward the central source. In some cases, interior and exterior rock drawings resembled these acoustical patterns. Since the resonance frequencies are well within the adult male voice range, one may speculate that some forms of human chanting, enhanced by the cavity resonance, were invoked for ritual purposes.

ISSN:0001-4966    

DOI:10.1121/1.414642

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

Ray techniques resolve individual physical mechanisms in describing wave radiation and scattering, and have been successfully applied to reparametrize the sound field of source excited elastic shells immersed in fluid but without internal load. Motivated on the same grounds, this paper reexamines, in ray acoustic terms, a submerged thin cylindrical shell mounted with an interior mass‐spring oscillator. The formulation is facilitated by spectral theory, just as for the empty shell case. As is well known now, internal loading is equivalent to inducing forces, and moments in more general situations, at the internal‐shell joints that act on the shell as external forces. However, the strengths of such forces are determined by the dynamical balance of the composite system at those joints, and may be ultimately expressed in terms of the empty shell displacements excited (by unit‐amplitude forces) and observed at the joints. Both flexural and membrane waves contribute to the latter, and hence their distinctive characteristics evince in the overall response via radiation of the coupling forces. With the modified ray acoustic algorithm developed recently for near‐field scattering, all the ray fields are represented uniformly over the entire azimuthal domain, and they yield accurate numerical results compared to the normal mode series in the frequency range 1≤ka≤25 considered here.

ISSN:0001-4966    

DOI:10.1121/1.414643

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

Scattering of an acoustic wave from a thin rough circular disk is studied using an integral equation method. The T matrix (transition matrix), which governs the relation between the incident and scattered fields, is determined using an integral representation of the Helmholtz equation. The rough surface is modeled by a superposition of a number of sinusoidal surfaces that are randomly translated and rotated with respect to each other. Some numerical results for the scattered field are presented in the case of an incident plane wave. One conclusion is that the amplitude of the backscattered field is not only dependent on parameters like frequency, angle of incidence, and overall characteristics of the surface like rms height and correlation function. The exact geometry of the rough object is also vitally important for its scattering properties, which implies that a statistical approach to the problem is of limited value.

ISSN:0001-4966    

DOI:10.1121/1.414644

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

The nonaxisymmetric acoustic field excited by a cylindrical tool placed off the axis of a fluid‐filled borehole is investigated. It is shown that the acoustic fields are composed of infinite numbers of the multipole fields with different orders. In cases in which the medium outside the borehole is an isotropic homogeneous elastic solid and a two‐phase medium, the dispersion and excitation of the mode waves such as Stoneley waves, pseudo‐Rayleigh waves, flexural waves, and screw waves are studied. The full waveforms in the time domain are also simulated and analyzed. It is pointed out that the components of the symmetric and nonsymmetric acoustic fields could be strengthened or weakened by adding and subtracting the two full waveforms logged in some opposite azimuths in a horizontal plane. A method of extraction of the shear wave is presented, and the relationship of the nonsymmetric acoustic field to the shear wave logging is analyzed.

ISSN:0001-4966    

DOI:10.1121/1.414645

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

A theoretical model was developed to evaluate the reduction of flexural wave that is generated by a line force applied on an infinite plate using a compliant baffle. The compliant baffle layer placed between the plate excited by a line force and a signal conditioning plate is designed for reducing pressure fluctuations from the vibrating plate. The baffle layer considered here is the compliant‐tube array, modeled by Junger [J. Acoust. Soc. Am.78, 1010 (1985)] to represent a homogeneous (dispersive) fluid layer. Effects of various parameters such as the aspect ratio of the compliant tube, the distance between tubes, and the damping of the tube material on the flexural wave reduction are presented. Calculations of noise reductions were made for both the dispersive and nondispersive fluid baffles.

ISSN:0001-4966    

DOI:10.1121/1.415231

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP