摘要:

The ultrasonic absorption coefficient has been measured in toluene by means of the spherical resonator method of Leonard and Wilson. Measurements were made in the temperature range 6°–40°C and in the frequency range 50–400 kc. The existence of a relaxation peak in this region, previously reported by Moen, has been confirmed, and a second peak has been identified at a lower frequency. The temperature dependence of the first peak indicates heat of reaction of 5.2 kcal/mole and an activation energy of 8.5 kcal/mole. This result is inconsistent with the hypothesis of a stretching vibration of the C–H bond, and suggests some sort of structural source for the absorption.

ISSN:0001-4966    

DOI:10.1121/1.1907489

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

The method of isochromates was used to measure the absorption of ultrasonic waves inm‐xylene, toluene, carbon tetrachloride, and benzene. The results are summarized in a table.

ISSN:0001-4966    

DOI:10.1121/1.1907497

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

When a photographic emulsion of the boiled type is treated with 800 kc ultrasonic energy at an energy level of 5 w/sq cm during the after‐ripening or digestion period, an increase the photographic sensitivity of that emulsion occurs. No significant change in the gamma or the grain size distribution of the emulsion results from this treatment. The mechanism appears to be a transport phenomenon which disrupts grain‐sensitizing‐agent concentration gradients in the intergrain gelatin matrix.

ISSN:0001-4966    

DOI:10.1121/1.1907503

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

Characteristics of spectra from relatively thick orifices differ from those from relatively thin. In a given range of Reynolds number, in many cases the jet may exist in any one of several reproducible jet‐tone states (metastable states) characteristic of the orifice. The dependence of the component frequencies of the jet‐tone spectra (expressed in terms of the orifice‐numberfd/(Δp/ρ)12)on Reynolds number[ρd(Δp/ρ)12]/μis shown, wheredis diameter of orifice;f, frequency; Δp, pressure difference across orifice; ρ, density; and μ, viscosity of gas. The orifice numbers of the components of the jet‐tone spectra generally tend to fall on a single array of equally spaced orifice‐number levels. Jet‐tones from the same orifice plate, characteristic of both thin as well as thick orifice plates, are found to coexist over a small transition range of orifice thickness‐diameter ratio. If the orifice number of the head of the most probable spectral mode for a given orifice thickness‐diameter ratio is noted, the same will be found again for the head of the most probable mode at approximate orifice thicknessest±nd, wherenis a small integer.

ISSN:0001-4966    

DOI:10.1121/1.1907475

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

The impedance presented to the inside surface of a hollow, liquid filled, radial cylinder of finite length has been determined theoretically. It was assumed that the liquid was retained by pressure‐release caps or one pressure‐release cap and one rigid cap at each end. For a loss‐free liquid it is shown that the reactance presented to the cylinder wall becomes infinite whenever the liquid has a longitudinal or coupled radial resonance.A sizeable resistance may appear when a viscous liquid is used. This is because the geometry of the arrangement is ideal for creating large shear losses. Exceptions to this occur for high frequencies where the wavelength is small in comparison to the cylinder length.

ISSN:0001-4966    

DOI:10.1121/1.1907490

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

This paper gives a theoretical study of the two‐dimensional flow of an incompressible, viscous fluid enclosed between two coaxial cylinders, one of which is oscillating. The Reynolds number is assumed to be small, and the Navier‐Stokes differential equations are solved by means of the method of successive proximations. Both for the first and second order solution the proper boundary conditions are applied. We have shown that there exist two stationary circulation systems in every quadrant, and that the direction of circulation is opposite in these two systems. The circulation velocities are calculated in detail, and the results are compared with experimental results referred to in an earlier paper. Some new experimental results, which are not published yet, are briefly mentioned. The agreement between theoretical and experimental results is excellent.In a discussion at the end of the paper we give the explanation of the remarkable fact that in some experiments the direction of circulation seems to reverse when the oscillation amplitude increases and exceeds a certain critical value.

ISSN:0001-4966    

DOI:10.1121/1.1907491

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

The time‐average forces exerted by the constraints of a vibrating system (radiation pressure, mean tension in a vibrating string, etc.) are easily computed from the adiabatic principle of Boltzmann and Ehrenfest (BE principle). The usual derivation from the “principle of varying action” is difficult.Here an equivalent principle (which gives in addition the time dependence of the forces) is derived from Lagrange's equations. It is also shown how similar results can be got from the solution of a linear differential equation with slightly variable coefficients.

ISSN:0001-4966    

DOI:10.1121/1.1907492

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

The sound field in the “shadow zone” (diffraction region) formed over a plane boundary in an atmosphere with a constant vertical temperature gradient is analyzed both theoretically and experimentally. The boundary condition at the plane is given by a normal acoustic impedance independent of the angle of incidence. As in the corresponding problem of underwater sound where the boundary is a pressure release surface, it is found that the major portion of the sound pressure in the shadow zone decays exponentially with distance at a rate proportional to the one‐third power of frequency and two‐thirds power of temperature gradient. The effect of boundary impedance enters mainly through its resistive component. The rate of sound decay for a pressure release boundary (zero impedance) is found to be 2.3 times that for a rigid boundary (infinite impedance).Sound pressure measurements in the shadow zone in a laboratory chamber in which a large temperature gradient was created were made for both hard and absorbing boundaries, and the results were found in essential agreement with theory.

ISSN:0001-4966    

DOI:10.1121/1.1907493

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

Flexural waves generated in a thin plate by a spark source are used to investigate properties of air‐coupled surface waves. Both ground shots and air shots are simulated in the model. Effects of source elevation, fetch of air pulse, and cancellation by destructive interference are studied.

ISSN:0001-4966    

DOI:10.1121/1.1907494

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP

摘要:

The problem of spherically symmetric wave propagation in homogeneous, isotropic elastic media of infinite extent has been examined frequently in recent years, and a number of analytical solutions have been reported in the literature for various initial conditions. Some interest has also been exhibited in the application of these relations to the transient phenomena occurring in metals when subjected to contact explosions. Under these conditions, an actual wave system can be approximated by postulating the existence of a spherical cavity in the interior of the medium and applying as the initial condition a pulse of exponentially decaying character. While no difficulty is encountered here in an analytic expression of the displacements, velocities and stresses occurring at each point of the medium as a function of location and time, it has been found highly desirable to represent these terms in pictorial form to permit a rapid evaluation of the nature of the disturbances in the region of interest. Consequently, numerical calculations have been performed on an IBM machine and the resultant data have been employed in a space‐time representation of these parameters.

ISSN:0001-4966    

DOI:10.1121/1.1907495

出版商:Acoustical Society of America    

年代:1955

数据来源: AIP