摘要:

The absorption of sound inMnSO4solutions was studied over the frequency range 1 to 55 Mc as a function of concentration, temperature, dielectric constant, and withD2Oas solvent. The absorption maximum in the range 1 to 10 Mc was verified, and also a secondary relaxation peak, not previously reported, was observed near 30 Mc. The primary relaxation frequency was decreased when the dielectric constant was lowered, while the secondary relaxation frequency was increased. The absorption cross section was increased when the dielectric constant was decreased. The primary relaxation frequency increased with increasing temperature following Arrhenius' equation. The activation energy was determined for both isodielectric and isocomposition solutions. Substitution ofD2Oas a solvent had no effect on the primary relaxation frequency but increased the absorption cross section. The secondary relaxation was not observed inD2Osolutions.These results indicate that the hydrogen ion is not involved in the rate‐determining reaction causing the observed relaxation effects. Furthermore, the results seem to rule out the reaction between two ions of unlike sign as the rate determining step in the primary relaxation process and to make the reaction between ions of like sign improbable. All observed data can be explained on the assumption that the reaction is between two dipole molecules.

ISSN:0001-4966    

DOI:10.1121/1.1908360

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

摘要:

The ultrasonic‐wave velocity and absorption for carbon tetrachloride, benzene, and carbon disulfide are measured by a pulse‐reflection method, at several temperatures, in the pressure range of 1 to 1360 atmospheres. Generally similar pressure effects are found in the three liquids. The velocity increases with pressure to about 1.4 times the atmospheric‐pressure value, while the relative absorption decreases to about 0.4. The structural relaxation theory, which is examined with reference to carbon tetrachloride, predicts approximately the pressure effect on the absorption at constant temperature, but gives erroneous predictions of the magnitude of the absorption, and of the effects of pressure on the absorption temperature coefficient and on the relaxation frequency. The thermal relaxation theory is partially examined with reference to carbon disulfide, although more extensive data and further refinement of the theory are needed for a rigorous test. In terms of this theory, the absorption data are consistent with approximate theoretical predictions of the effect of pressure upon the relaxation frequency and upon the relaxational portion of the specific heat. Over all, the study tends to confirm the thermal relaxation theory of the excess absorption in nonassociated liquids. It is shown also that the Tonks equation of state gives approximately correct values of the pressure coefficient of sound velocity for carbon disulfide.

ISSN:0001-4966    

DOI:10.1121/1.1908362

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

摘要:

The velocity of ultrasonic waves was measured inCO2containing a 0.01 mole‐fraction of water vapor at the frequencies 1001.8 kc and 540.6 kc in the range from 0.5 Mc/atmos to 6 Mc/atmos at 35.1°C. The mixture was prepared at one fixedCO2andH2Opressure to give greater assurance of constant composition and was analyzed for water content by gravimetry. Variation of pressure within the interferometer was obtained by varying the rate of flow with a precision needle valve. Complete symmetry of current peak structure and hence a more accurate determination of wavelength was obtained by the technique of continually compensating for frequency shift due to the variation of acoustic impedance of the gas column. The velocity was found to vary from 286.2 m/sec at 6 Mc/atmos to 278.1 m/sec at 0.5 Mc/atmos. The experimental points fit the curve for asinglerelaxation time of 3.03×10−7sec corresponding to an inflection frequency of 740 kc/atmos.

ISSN:0001-4966    

DOI:10.1121/1.1908364

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

摘要:

Exact steady‐state solutions for both longitudinal waves and shear waves traveling in isotropic rods of circular cross section are analyzed. Numerical examples are described for rods of large diameter to wavelength ratio.The effect of mode conversion on the propagation of short duration longitudinal wave trains is considered; and an approximate expression for the resulting loss is developed.Experimental results for 10–25 Mc/sec longitudinal and shear waves in fused silica rods of 1.13 cm radius are described.

ISSN:0001-4966    

DOI:10.1121/1.1908366

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

摘要:

The diffraction theory developed by Sommerfeld and extended by Pauli is used to approximate the relative amplitude of the diffracted pulses from a wedge in a solid. The geometric terms are neglected and the amplitude of the diffracted wave is obtained from the contour integral. Barium titanate transducers are used for sources and receivers on tar and concentrate models to check the predictions of the theory. Several relative amplitudeversusdistance curves are given for regions where the diffracted pulse is separated from other waves. The experimental and theoretical curves agree to ±4 decibels in the regions tested.

ISSN:0001-4966    

DOI:10.1121/1.1908368

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1908370

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1908373

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

摘要:

A sing‐around ultrasonic velocimeter was used to locate the temperature for which the velocity of sound in water is a maximum at 73.95°C. It is suggested that water held near this temperature is a suitable standard for intercomparison and calibration of instruments.

ISSN:0001-4966    

DOI:10.1121/1.1908375

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

摘要:

A sing‐around ultrasonic velocimeter was used to show that dissolved air has a negligible effect (less than 10 ppm) on the speed of sound in water at 31.8°C and 0°C.

ISSN:0001-4966    

DOI:10.1121/1.1908377

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP

摘要:

Acoustical shadows observed in the transmission of sound through biological material are accounted for by refraction and total reflection.

ISSN:0001-4966    

DOI:10.1121/1.1908381

出版商:Acoustical Society of America    

年代:1956

数据来源: AIP