Underwater sound

Titanium forms a series of oxoanions called titanates, which are prepared by heating Ti02 with a stoichiometric amount of the oxide or carbonate of a second metal. One of these compounds, barium titanate, BaTi03, is piezoelectric, which means that it becomes electrically charged when it is mechanically distorted. The ability to convert mechanical vibration into an electrical signal makes barium titanate useful for underwater sound detection. 

A bomb, when dropped by a disabled vessel or aircraft, sinks into the ocean to a predetermined depth, where the hydrostatic pressure causes it to expld. This provides an underwater sound signal which can be picked up at distances up to 3000 miles away, enabling triangulation to the site of the expln (Refs 1 2). A modification of this concept (Ref 3) resulted in the design of a... 

C.L. Darner, Sonic cavitation in water, Naval Research Laboratory Underwater Sound Research Division Report 7131, ADA031182, NRL-USRD, 1970. 

ProdjiclsrMatermls for Underwater Sound Applications, B. F. Goodrich Aerospace and Defense Products Publication... 

C. L. Darner, An Anechoic Tank for Underwater Sound Measurements... 

W. J. Toulis. Simple Anechoic Tank for Underwater Sound , J. Acoust. 

W. S. Cramer, T. F. Johnston, Underwater Sound Absorbing Structures ,... 

Lastinger, J. L. and Sabin, G. A. A PDP-8 Fortan Program for Reduction of Acoustic-Impedance Data. Naval Research Laboratory, Underwater Sound Reference Detachment, Rept 6906,... 

Underwater Sound Reference Detachment, U.S. Naval Research Laboratory, P.O. Box 568337, Orlando, FL 32856-8337 Polymer Technologies, Inc., University of Detroit, Detroit, MI 48221... 

Portions of this work were funded by the Naval Research Laboratory/Underwater Sound Reference Detachment, Orlando, Florida and by the Robert A. Welch Foundation, Houston, Texas. 

For medical applications, in our view, mechanical resonances (see Section 9.4.2.3) present barriers to antibody interaction such that these soft elastic biomaterials exhibit a remarkable biocompatibility otherwise considered impossible for foreign proteins. As a specific example for medical and nonmedical applications, the author believes that the finding of mechanical resonances, so innovative as to be denounced as artifact by those constrained by the idols of the present, constitutes opportunities for the future ranging from biosensors capable of single molecule detection to hearing protection and underwater sound absorption. 

John Frederick Ripken was educated at University of Minnesota, Minneapolis MN, obtaining the BS degree in civil engineering in 1934, and in 1941 the MS degree. He was there an instructor at the Dept, of Mathematics and Mechanics from 1937 to 1941, a research engineer at the Columbia University until 1945 within the Navy Underwater Sound Laboratory, and then until 1946 a hydraulic engineer of the Navy Department, at its David Taylor Model Basin,... 

Underwater Sound. Applications for underwater acoustics include devices for underwater communication by acoustic means, remote control devices, underwater navigation and positioning systems, acoustic thermometers to measure ocean temperature, and echo sounders to locate schools of fish or other biota. Low-frequency devices can be used to explore the seabed for seismic research. 

Smith, L.G., Photographic Investigation of the Reflection of Plane Shocks in Air, USRD Rept. No. 6271, Underwater Sound Reference Detachment, U.S. Navy or NORC Rep. No. A 2350, Naval Ordnance Research Center, U.S. Navy, 1945. 

Introduction Underwater Propagation Underwater Sound Systems Components and Processes Signal Processing Functions Advanced Signal Processing Application... 

D = depth, m S = salinity, parts per thousand T = temperature, °C. (Source Urick, R.J. 1983. Principles of Underwater Sound, p. 113. McGraw-Hill, New York.)... 

If the sound speed is a minimum at a certain depth below the surface, then this depth is called the axis of the underwater sound channel (also called the sound fixing and ranging (SOFAR) channel.) The sound velocity increases both above and below this axis. When the sound wave travels through a medium with a sound speed gradient, the direction of travel of the sound wave is bent toward the area of lower sound speed. 

FIGURE 17.40 Typical sound paths between source and receiver, in fathom unit of length or depth generally used for underwater measurements where 1 fethom = 6 ft. (Source Cox, A.W. 1974. Sonar and Underwater Sound, p. 25. Lexington Books, D.C. Heath and Co., Lexington, MA.)... 

Urick, R.J. 1983. Principles of Underwater Sound. McGraw-Hill Book Company, New York. 

Digital Signal Processing for Sonar, (Knight, Pridham, and Kay, 1981) and Sonar System Technology (Winder, 1975) are informative and detailed tutorials on underwater sound systems. Also the March 1972 issue of The Journal of Acoustical Society of America, Vol. 51, No. 3 (Part 2), has historical and review papers on underwater acoustics related topics. 

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