Shear‐wave amplitude anomalies in south‐central Wyoming

1996 ◽  
Vol 15 (8) ◽  
pp. 913-920 ◽  
Author(s):  
Robert R. Kendall ◽  
J-Michael Kendall
Keyword(s):  
Shear Wave ◽  
Wave Amplitude ◽  
South Central

scholarly journals Absolute stress measurement of structural steel members with ultrasonic shear-wave spectral analysis method

2017 ◽  
Vol 18 (1) ◽  
pp. 216-231 ◽  
Author(s):  
Zuohua Li ◽  
Jingbo He ◽  
Jun Teng ◽  
Qin Huang ◽  
Ying Wang
Keyword(s):  
Spectral Analysis ◽  
Structural Steel ◽  
Shear Wave ◽  
Wave Amplitude ◽  
Stress Measurement ◽  
Amplitude Spectrum ◽  
Uniaxial Stress ◽  
Wave Pulse ◽  
Steel Members ◽  
Pulse Echo

Absolute stress in structural steel members is an important parameter for the design, construction, and servicing of steel structures. However, it is difficult to measure via traditional approaches to structural health monitoring. The ultrasonic time-of-flight method has been widely studied for monitoring absolute stress by measuring the change in ultrasonic propagation time induced by stress. The time-of-flight of the two separated shear-wave modes induced by birefringence, which is particular to shear waves, is also affected by stress to different degrees. Their synthesis signal amplitude spectrum exhibits a minimum that varies with stress, which makes it a potential approach to evaluating uniaxial stress using the shear-wave amplitude spectrum. In this study, the effect of steel-member stress on the shear-wave amplitude spectrum from the interference of two shear waves produced by birefringence is investigated, and a method of uniaxial absolute stress measurement using shear-wave spectral analysis is proposed. Specifically, a theoretical expression is derived for the shear-wave pulse-echo amplitude spectrum, leading to a formula for evaluating uniaxial absolute stress. Three steel-member specimens are employed to investigate the influence of uniaxial stress on the shear-wave pulse-echo amplitude spectrum. The testing results indicate that the amplitude spectrum changes with stress and that the inverse of the first characteristic frequency in the amplitude spectrum and its corresponding stress exhibit a near-perfect linear relationship. On this basis, the uniaxial absolute stress of steel members loaded by a test machine is measured by the proposed method. Parametric studies are further performed on three groups of steel members made of 65# steel and Q235 steel to investigate the factors that influence the testing results. The results show that the proposed method can measure and monitor steel-members uniaxial absolute stress on the laboratory scale and has potential to be used in practical engineering with specific calibration.

Measurement of Ultrasonic Shear Wave Amplitude Using Raman-Nath Parameter

1987 ◽  
Vol 26 (S1) ◽  
pp. 247
Author(s):  
Hiroki Kojoh ◽  
Kazuo Arakawa ◽  
Kiyoshi Takahashi ◽  
Satoshi Nagai
Keyword(s):  
Shear Wave ◽  
Wave Amplitude ◽  
Ultrasonic Shear

scholarly journals Development of an intravascular ultrasound elastography based on a dual-element transducer

2018 ◽  
Vol 5 (4) ◽  
pp. 180138 ◽  
Author(s):  
Cho-Chiang Shih ◽  
Pei-Yu Chen ◽  
Teng Ma ◽  
Qifa Zhou ◽  
K. Kirk Shung ◽  
...  
Keyword(s):  
Shear Wave ◽  
Intravascular Ultrasound ◽  
Elastic Properties ◽  
Wave Velocity ◽  
Wave Amplitude ◽  
Ex Vivo ◽  
Ultrasound Elastography ◽  
Elasticity Imaging ◽  
Dual Frequency ◽  
Peak Displacement

The ability to measure the elastic properties of plaques and vessels would be useful in clinical diagnoses, particularly for detecting a vulnerable plaque. This study demonstrates the feasibility of the combination of intravascular ultrasound (IVUS) and acoustic radiation force elasticity imaging for detecting the distribution of stiffness within atherosclerotic arteries ex vivo . A dual-frequency IVUS transducer with two elements was used to induce the propagation of the shear wave (by the 8.5 MHz pushing element) which could be simultaneously monitored by the 31 MHz imaging element. The wave-amplitude image and the wave-velocity image were reconstructed by measuring the peak displacement and wave velocity of shear wave propagation, respectively. System performance was verified using gelatin phantoms. The phantom results demonstrate that the stiffness differences of shear modulus of 1.6 kPa can be distinguished through the wave-amplitude and wave-velocity images. The stiffness distributions of the atherosclerotic aorta from a rabbit were obtained, for which the values of peak displacement and the shear wave velocity were 3.7 ± 1.2 µm and 0.38 ± 0.19 m s −1 for the lipid-rich plaques, and 1.0 ± 0.2 µm and 3.45 ± 0.45 m s −1 for the arterial walls, respectively. These results indicate that IVUS elasticity imaging can be used to distinguish the elastic properties of plaques and vessels.

scholarly journals Three-dimensional shear-wave quality factor, Qs(f), model for south-central Gulf of California, Mexico obtained from inversion of broadband data

2021 ◽  
Vol 60 (2) ◽  
pp. 140-160
Author(s):  
Sanjay Kumar ◽  
Anand Joshi ◽  
Raul R. Castro ◽  
Sandeep Singh ◽  
Shri Krishna Singh
Keyword(s):  
Quality Factor ◽  
Shear Wave ◽  
Gulf Of California ◽  
Wave Attenuation ◽  
Three Dimensional ◽  
Ocean Bottom ◽  
Inversion Algorithm ◽  
Attenuation Relations ◽  
South Central ◽  
Dependent Relation

Abstract          We apply an iterative inversion scheme, initially developed by Hashida and Shimazaki (1984) and later modified by Joshi et al., (2010), to estimate three - dimensional shear - wave quality factor, Qs(f), of south-central Gulf of California, Mexico. An area of 230 km x 288 km in this region is divided into 108 rectangular blocks of different Qs(f). We use 25 well-located earthquakes recorded at three broadband stations of the regional network RESBAN operated by CICESE (Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California) and three Ocean Bottom Seismographs (OBS) of the Sea of Cortez Ocean Bottom Array (SCOOBA) experiment.  This dataset permits us to obtain Qs(f) estimates of different blocks using the modified inversion algorithm. Qs(f) is obtained at various frequencies in 0.16 - 7.94 Hz range. We found that the estimated Qs structure correlates with geological and tectonic models of the region proposed in previous studies. A regional frequency-dependent relation using all 1944 values of shear-wave quality factor is obtained at 18 different frequencies in all blocks can be approximated by a function of the form Qs(f) = 20 f 1.2. This relation is typical in a tectonically active region with high S-wave attenuation and is similar to attenuation relations reported by other authors for the Imperial Valley, California region.

Variation of shear-wave amplitude during frictional sliding

1993 ◽  
Vol 30 (7) ◽  
pp. 779-784 ◽  
Author(s):  
W.-Y. Chen ◽  
C.W. Lovell ◽  
G.M. Haley ◽  
L.J. Pyrak-Nolte
Keyword(s):  
Shear Wave ◽  
Wave Amplitude ◽  
Frictional Sliding

scholarly journals Characteristics of mantle fabrics beneath the south-central United States: Constraints from shear-wave splitting measurements

Geosphere ◽  
2008 ◽  
Vol 4 (2) ◽  
pp. 411 ◽  
Author(s):  
Stephen S. Gao ◽  
Kelly H. Liu ◽  
Robert J. Stern ◽  
G. Randy Keller ◽  
John P. Hogan ◽  
...  
Keyword(s):  
United States ◽  
Shear Wave ◽  
Shear Wave Splitting ◽  
The South ◽  
South Central ◽  
Wave Splitting ◽  
Central United States

scholarly journals MR elastography of the human heart: Noninvasive assessment of myocardial elasticity changes by shear wave amplitude variations

2008 ◽  
Vol 61 (3) ◽  
pp. 668-677 ◽  
Author(s):  
Ingolf Sack ◽  
Jens Rump ◽  
Thomas Elgeti ◽  
Abbas Samani ◽  
Jürgen Braun
Keyword(s):  
Shear Wave ◽  
Human Heart ◽  
Wave Amplitude ◽  
Mr Elastography ◽  
Noninvasive Assessment ◽  
Myocardial Elasticity
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