Practice for Measurement of Ultrasonic Attenuation Coefficients of Advanced Ceramics by Pulse-Echo Contact Technique

2018 ◽  
Author(s):  
Keyword(s):  
Ultrasonic Attenuation ◽  
Advanced Ceramics ◽  
Attenuation Coefficients ◽  
Pulse Echo

Ultrasonic Attenuation Measurements of in Vivo Human Muscle

1982 ◽  
Vol 4 (3) ◽  
pp. 290-295 ◽  
Author(s):  
J. Ophir ◽  
N. F. Maklad ◽  
R. H. Bigelow
Keyword(s):  
Analysis Of Variance ◽  
Ultrasonic Attenuation ◽  
Human Muscle ◽  
Normal Range ◽  
Attenuation Coefficients ◽  
Quadriceps Femoris Muscle ◽  
Pulse Echo ◽  
Pulse Echo Method ◽  
Femoris Muscle

Attenuation measurements were performed on the quadriceps femoris muscle of 10 normal volunteers. The measurements were made using a statistical narrowband pulse echo method operating at 4.3 MHz. The results show a normal range of 4.71 ± 0.44 dB cm-1 (mean ± S.D.). A one-way analysis of variance was performed on the data which concluded that the populations of attenuation coefficients among the subjects were indeed distinct at the p < 0.0005 level.

Evaluation of Thermal Degradation of 2.25Cr-1Mo Steel by High Frequency Ultrasonic Attenuation Measurement

2005 ◽  
Vol 475-479 ◽  
pp. 257-260 ◽  
Author(s):  
Jai Won Byeon ◽  
C.S. Kim ◽  
S.I. Kwun ◽  
S.J. Hong
Keyword(s):  
Attenuation Coefficient ◽  
High Frequency ◽  
Ultrasonic Attenuation ◽  
Attenuation Coefficients ◽  
Low Frequencies ◽  
High Frequencies ◽  
Noticeable Increase ◽  
Mean Size ◽  
Longitudinal Ultrasonic Wave ◽  
Degradation Time

It was attempted to assess nondestructively the degree of isothermal degradation of 2.25Cr-1Mo steel by using high frequency longitudinal ultrasonic wave. Microstructural parameter (mean size of carbides), mechanical property (Vickers hardness) and ultrasonic attenuation coefficient were measured for the 2.25Cr-1Mo steel isothermally degraded at 630°C for up to 4800 hours in order to find the correlation among these parameters. The ultrasonic attenuation coefficients at high frequencies (over 35MHz) were observed to increase rapidly in the initial 1000 hours of degradation time and then slowly thereafter, while the ones at low frequencies showed no noticeable increase. Ultrasonic attenuation at high frequencies increased as a function of mean size of carbides. Ultrasonic attenuation coefficient was found to have a linear correlation with the hardness, and suggested accordingly as a potential nondestructive evaluation parameter for assessing the mechanical strength reduction of the isothermally degraded 2.25Cr-1Mo steel.

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