摘要:

A generalized theoretical treatment is presented of a problem which has direct application tothe phenomenon of multiple-echo patterns as employed for propagational studies of high frequency sound waves in various media. An analysis is made of the functional dependence of the number of observable echoesNin terms of a prescribed threshold sensitivitydb* of a detecting device, and the storage medium parameters, which are the effective absorption coefficientaand the boundary reflection coefficientR. The equation derived is:N = {db*/10+logR − log(1 − R )}/{logR − αd loge}, wheredis the length of the storage system. This relation has valuesRoptfor whichNis a maximum, and it is shown thatNmax = 1/1 − Ropt. The solutions forNmaxare actually difficult to express explicitly sinceRoptmust be evaluated from the condition for a maximumRopt1 − Ropt logRopt+log(1 − Ropt) −αd loge1 − Ropt=db*10. Asymptotic solutions are discussed, and detailed examination of the case of zero loss is given in the form of several graphical results.

ISSN:0001-4966    

DOI:10.1121/1.1906747

出版商:Acoustical Society of America    

年代:1951

数据来源: AIP

摘要:

Laboratory measurements of sound velocity in sea water samples from the Caribbean and Middle Atlantic have been made by means of a three‐megacycle ultrasonic interferometer. The results at various salinities and temperatures show that the velocity values in current use (Kuwahara's tables) are too low by approximately three meters/second.In addition, variations in the dissolved air content were found to have negligible effect on sound velocity and absorption. The sulfate/chloride ratio was determined as quite constant in a given region of the sea. Finally, it was established that the velocity and adiabatic compressibility observed for sea water are explainable on the basis of a linear summation of the effects of the individual dissolved salts.

ISSN:0001-4966    

DOI:10.1121/1.1906748

出版商:Acoustical Society of America    

年代:1951

数据来源: AIP

摘要:

Publications by other investigators on the production of cavitation in liquids and its effects are discussed. Several points in favor of low frequency cavitation studies are listed. Two methods were used by the author to feed power at about 30 cycles/sec into the liquids. In one method a thick‐walled Lucite tube containing the liquid was attached to the vibrating element of a Sonntag Universal Fatigue Machine. Similar results were obtained with a modified paint spraying compressor which had a vibrating diaphragm instead of a metal piston. Photographs show both methods. Emulsions and suspensions were made in a few minutes, the cleansing effect on cloth soiled in a standard manner was tested and the oxide coating on aluminum foil was removed. Probably greater corrosive effects could be obtained with the same power at higher frequencies.

ISSN:0001-4966    

DOI:10.1121/1.1906749

出版商:Acoustical Society of America    

年代:1951

数据来源: AIP

摘要:

The possibility of excitation of nonlinear elastic system by the combination frequencies produced when two forces of different frequencies act on the system is investigated, using the approximate method of Rayleigh. Experimental evidence is cited to support the results of the calculations, namely, that the combination frequencies need not be considered as potential sources of excitation.

ISSN:0001-4966    

DOI:10.1121/1.1906750

出版商:Acoustical Society of America    

年代:1951

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1906752

出版商:Acoustical Society of America    

年代:1951

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1906754

出版商:Acoustical Society of America    

年代:1951

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1906755

出版商:Acoustical Society of America    

年代:1951

数据来源: AIP