Results 211 to 220 of about 21,616 (265)
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Acoustic impedance of the maternal abdomen
The Journal of the Acoustical Society of America, 1993Contact sensors to monitor fetal heart, breathing, and movement sounds with increased sensitivity and bandwidth are under development. To understand the inherent acoustical properties of the maternal abdomen and its interaction with these sensors, the driving-point impedance Z(jω) was measured in nine women during their last trimester of pregnancy.
G R, Wodicka +3 more
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Acoustic Neuromas and the Acoustic Impedance of the Ear
Journal of Speech and Hearing Disorders, 1973The acoustic impedance at the tympanic membrane was measured at frequencies in the range 100–1000 Hz and found to be abnormal on the affected side in four patients with acoustic neuroma. In all four the resistance was abnormally high at low frequencies on the affected side, and in three the reactance of the affected ear was raised relative to that of ...
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A Method of Measuring Acoustic Impedance
The Journal of the Acoustical Society of America, 1932An apparatus s described whereby acoustic impedances may be measured in terms of a known acoustic impedance and the complex ratios of two electrical potentiometer readings to a third. As a known impedance, there is chosen the reactance of a closed tube of uniform bore which is an eighth wave-length long.
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Surface acoustic impedance and causality
The Journal of the Acoustical Society of America, 2001Several models that are commonly used to calculate the surface acoustic impedance of porous materials are examined in light of the causality requirement in its nonlocal and its approximate local forms. Strict (nonlocal) causality requires that the imaginary part of the surface acoustic impedance be the Hilbert transform of the real part.
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Acoustic Impedance from Motional Impedance Diagrams
The Journal of the Acoustical Society of America, 1948When an acoustic load is coupled to an electromagnetic transducer through a length of air column, there is a critical length at which an increment in acoustic load produces a maximum increment in electrical impedance. The method described makes use of this critical coupling to obtain an optimum precision in determining an acoustical impedance.
R. D. Fay, J. E. White
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Acoustical impedance measurement.
The Journal of the Acoustical Society of America, 2008Many components of specialty transducers have extremely tight acoustic impedance tolerances and become difficult to measure in a production environment. Comparing the device to the acoustical impedance of a cavity is one method of determining its acoustical impedance. A precise method of determining the acoustical impedance is described.
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A Wide Range Adjustable Acoustic Impedance
The Journal of the Acoustical Society of America, 1944A method for obtaining a wide range of calculable impedance values has been developed. Three telescoping tubes are used, one being acoustically “infinite” in length. This “infinite” tube is used as a convenient, calculable impedance terminating the device.
Willard F. Meeker, Frank H. Slaymaker
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Tonndorf and acoustic impedance
The Journal of the Acoustical Society of America, 1990Juergen was full of ideas that reflected his excellent understanding of the limits of technology and science. At first many of his ideas seemed impractical, but in my experience, he was usually right on target and got the results or data he was after. I learned many practice things from him in the lab; almost every encounter brought a new point of view
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Acoustic impedance estimation using calibration curve for scanning acoustic impedance microscope
2016 International Conference on Knowledge Creation and Intelligent Computing (KCIC), 2016Ultrasonic has been used since several decades ago. One of ultrasonic application is used in medical field to observe mechanical properties of target, such as speed of sound, density, acoustic impedance, attenuation, etc. Several methods are also available to estimate mechanical property of target.
Agus Indra Gunawan +5 more
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Acoustic Impedance Inversion of VSP data
Proceedings, 2013During the drilling stage, VSP plays an important role in predicting the depth of target strata and the lithologic characteristics of the deep strata ahead of the drill bit. Therefore, using VSP data to predict ahead of the drill bit has become a popular topic.
Jing Wang, Yanpeng Li, Jinling Du
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