ISSN:0001-4966    

DOI:10.1121/1.414686

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414772

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414773

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414774

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.414775

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:10.1121/1.414777

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

Sound is more than an ‘‘oscillation...in a medium’’ or ‘‘an auditory sensation evoked by the oscillation.’’ From an academic standpoint it involves physical sciences, engineering, life sciences, and art. From an application standpoint it is also related to invention, design, economics, business, and even legislation. These relationships can be described and diagrammed in several different ways. The field of musical acoustics is used as an example of the interaction among the various disciplines.

ISSN:0001-4966    

DOI:10.1121/1.414706

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

In the interaction of an acoustic field with a moving airframe, a canonical initial value problem for an acoustic field induced by an unsteady source distributionq(t,x) withq≡0 fort≤0, in a medium moving with a uniform unsteady velocityU(t)î in the coordinate systemxfixed on the airframe, is encountered. Signals issued from a source pointSin the domain of dependenceDof an observation pointPat timetwill arrive at pointPmore than once corresponding to different retarded times τ in the interval [0,t]. The number of arrivals is called the multiplicity of the pointS. The multiplicity equals one if the velocityUremains subsonic and can be greater whenUbecomes supersonic. For an unsteady uniform flowU(t)î, rules are formulated for defining the smallest number ofIsubdomainsViofDwith the union ofViequal toD. Each subdomain has multiplicity 1 and a formula for the corresponding retarded time. The number of subdomainsViwith nonempty intersection is the multiplicitymof the intersection. The multiplicity is at mostI. Examples demonstrating these rules are presented for media at accelerating and/or decelerating supersonic speed.

ISSN:0001-4966    

DOI:10.1121/1.414707

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

Two iterative methods for the calculation of acoustic transmission through a rough interface between two media are compared. The methods employ a continuous version of the conjugate gradient technique. One method is based on plane‐wave expansions and the other on boundary integral equations and Green’s functions. A preconditioner is presented which improves the convergence for spectra that include evanescent modes. The methods are compared with regard to computational efficiency, rate of convergence, and residual error. The sound field differences are determined for a focused ultrasound beam distorted by surfaces having a Gaussian roughness spectrum. The differences are evaluated from the root‐mean‐square differences on the rough surface and in the focal plane.

ISSN:0001-4966    

DOI:10.1121/1.414708

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP

摘要:

The antiplane shear, SH or scalar problem of scattering from an interface characterized by a narrow region of heterogeneity is considered. An approximate integral representation of the scattered wave fields in terms of a Green’s function for a reference problem, and the stress and momentum polarizations averaged through the thickness of the interface is derived. Providing certain material contrast parameters areO(1), the error in this expression is formallyO(kh)2, wherekis the wave number and 2his the thickness of the interface. To find the unknown polarizations we specialize to a model configuration that is periodic over a length scale much greater than the characteristic length scales of the heterogenities in the interface. This allows an exact formulation in terms of an infinite system of algebraic equations. Expressions modeling the reflection and transmission measured by a coaxial, confocal pair of transducers are then derived so that the effects of the transducer can be included in the modeling. These coefficients are calculated in terms of the solution of the algebraic system. Numerical results for several different model interfaces are presented.

ISSN:0001-4966    

DOI:10.1121/1.414709

出版商:Acoustical Society of America    

年代:1996

数据来源: AIP