摘要:

It has been shown how the standing‐wave ratio of an ultrasonic field can be obtained by the use of a particular holographic method that permits spatial separation and independent measurement of the light intensities of all the optical subcomponents present in the diffraction spectrum of an ultrasonic grating. Experimental measurements have been performed relative to ultrasonic fields with arbitrary standing‐wave ratios, obtained by making use of acoustic transmission lines having particular termination impedances.

ISSN:0001-4966    

DOI:10.1121/1.1911829

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Additional velocity measurements and first absorption measurements indicate a single relaxation process in freon 113. There is some discrepancy between the relaxation time calculated from velocity dispersion and that from absorption, but the absorption data fit theoretical calculations very well. Calculations indicate that the effect of rotational isomerism is too small to be measured in this vapor with present apparatus. The relaxation time measured in freon 113 at 53°C is 0.53 × 10−8sec from absorption data.

ISSN:0001-4966    

DOI:10.1121/1.1911830

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The propagation of initial disturbances in gas mixtures is studied by means of an asymptotic analysis. Three new nonpropagating diffusively damped modes are found to exist in addition to the three modes (two propagating and one nonpropagating) found in a simple gas. Of the three original modes, only the nonpropagating heat‐conduction mode is unaffected by diffusion, while the two propagating modes are now diffusively as well as viscously damped. The analysis shows that, in certain mixtures, the diffusive damping can be as large as viscous damping.

ISSN:0001-4966    

DOI:10.1121/1.1911831

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The acoustic radiation force on a solid sphere suspended freely in a plane progressive sound field is calculated taking into account the elasticity of the sphere. The radiation force versuskacurve,kabeing the radius times the wavenumber in the surrounding medium, shows sharp maximums or minimums corresponding to resonance in every normal mode of free vibration of the sphere. The measurements made in our laboratory are in good agreement with the theory. The accuracy of absolute acoustic‐intensity determination by the radiation‐force method will be improved by the use of the present theory instead of King's.

ISSN:0001-4966    

DOI:10.1121/1.1911832

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

An acoustical interferometer that operates at 1 GHz at both room and cryogenic temperatures is described. The experimental system features a method yielding a direct measurement of the absolute attenuation.

ISSN:0001-4966    

DOI:10.1121/1.1911833

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Sound‐wave attenuation measurements were made in air contained in a 0.016‐in.‐diam tube at 15–30 Hz. The data obtained are at room temperature and at pressure of 1 atm. The measured attenuation coefficients provide substantial verification of the existing small‐tube theory of Weston [Proc. Phys. Soc. (London)B66, 695–709 (1953)]. The results suggest a possible method of determining viscosities of gases.

ISSN:0001-4966    

DOI:10.1121/1.1911834

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The differential equation of acoustic rays in two‐dimensional rotating flows is derived, and is integrated for the cases of rigid‐body rotation and the potential vortex, with a point acoustic source. In the case of rigid‐body rotation, the rays are bent in the direction of rotation, resulting in defocusing on the side of the acoustic source near the center of rotation and focusing on the opposite side. In the case of the potential vortex, a number of rays are trapped by the vortex and spiral towards the center. Other rays at first appear to be trapped, but then reach a turning point and leave the vortex. These rays are substantially deflected and defocused. In addition, with a circulation corresponding to a Mach number of 0.5 at the acoustic source, a caustic is formed. However, with one‐half that circulation, the caustic does not appear.

ISSN:0001-4966    

DOI:10.1121/1.1911835

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

A method is presented for reconstructing the shape of an object from a measurement of the diffraction pattern of the object when placed in the path of a monochromatic sound wave. It is shown that measurements of amplitude and phase in a plane at a distance from the object enable reconstruction of the wavefront everywhere. It is further shown that measurements at only a discrete set of points (a square lattice of suitable dimensions) suffice. The results of computer simulation, as well as of an experiment conducted in an anechoic chamber, are presented.

ISSN:0001-4966    

DOI:10.1121/1.1911836

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Upper and lower bounds of the first four natural frequencies of elastic clamped arcs, which vibrate in a plane perpendicular to that of the initial curvature of the arcs, are obtained by applying to curved beams a method, based on differential operator theory, originally proposed by Lehmann and Maehly. The principal advantage of the method is that it provides, at the same time, the set of upper and lower bounds of natural frequencies of vibrating systems. The center lines of the arcs are in the forms of circles, cycloids, catenaries, and parabolas. Numerical results are presented in tabular form. The upper‐bound frequencies so obtained are compared with those obtained by the application of the Rayleigh‐Ritz method.

ISSN:0001-4966    

DOI:10.1121/1.1911837

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The equation for longitudinal displacement in each ofksections of a composite elastic solid is solved. The elastic composite consists ofkdiscrete plates (separately isotropic), each of different material, joined solidly at theirk− 1 interfaces. The composite plates are initially unstressed, and are acted upon, at their two mutual external boundaries, by separate arbitrary time‐dependent stresses. The internal boundary conditions maintain across each interface the equality of displacement and stress. The solution is obtained using a new orthogonality relationship. The solution for the displacement given for arbitraryk.

ISSN:0001-4966    

DOI:10.1121/1.1911838

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP