Nonlinear shear wave beams

2007 ◽  
Vol 121 (5) ◽  
pp. 3182-3182
Author(s):  
Mark S. Wochner ◽  
Mark F. Hamilton ◽  
Evgenia A. Zabolotskaya
Keyword(s):  
Shear Wave ◽  
Nonlinear Shear

scholarly journals Observation of nonlinear shear wave propagation using magnetic resonance elastography

2004 ◽  
Vol 52 (4) ◽  
pp. 842-850 ◽  
Author(s):  
Ingolf Sack ◽  
Christopher K. Mcgowan ◽  
Abbas Samani ◽  
Chris Luginbuhl ◽  
Wendy Oakden ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Magnetic Resonance ◽  
Shear Wave ◽  
Magnetic Resonance Elastography ◽  
Nonlinear Shear

scholarly journals Nonlinear shear wave in a non Newtonian visco-elastic medium

2012 ◽  
Vol 19 (6) ◽  
pp. 062301 ◽  
Author(s):  
D. Banerjee ◽  
M. S. Janaki ◽  
N. Chakrabarti ◽  
M. Chaudhuri
Keyword(s):  
Elastic Medium ◽  
Shear Wave ◽  
Nonlinear Shear

Nonlinear shear wave resonator consisting of a relaxing material

2017 ◽  
Vol 142 (4) ◽  
pp. 2723-2723 ◽  
Author(s):  
John M. Cormack ◽  
Mark F. Hamilton
Keyword(s):  
Shear Wave ◽  
Wave Resonator ◽  
Nonlinear Shear

Weakly nonlinear shear waves

1998 ◽  
Vol 372 ◽  
pp. 71-91 ◽  
Author(s):  
FALK FEDDERSEN
Keyword(s):  
Shear Wave ◽  
Surf Zone ◽  
Second Harmonic ◽  
Shear Waves ◽  
Finite Amplitude ◽  
Shear Instability ◽  
Weakly Nonlinear ◽  
Wide Range ◽  
Alongshore Current ◽  
Nonlinear Shear

Alongshore propagating low-frequency O(0.01 Hz) waves related to the direction and intensity of the alongshore current were first observed in the surf zone by Oltman-Shay, Howd & Birkemeier (1989). Based on a linear stability analysis, Bowen & Holman (1989) demonstrated that a shear instability of the alongshore current gives rise to alongshore propagating shear (vorticity) waves. The fully nonlinear dynamics of finite-amplitude shear waves, investigated numerically by Allen, Newberger & Holman (1996), depend on α, the non-dimensional ratio of frictional to nonlinear terms, essentially an inverse Reynolds number. A wide range of shear wave environments are reported as a function of α, from equilibrated waves at larger α to fully turbulent flow at smaller α. When α is above the critical level αc, the system is stable. In this paper, a weakly nonlinear theory, applicable to α just below αc, is developed. The amplitude of the instability is governed by a complex Ginzburg–Landau equation. For the same beach slope and base-state alongshore current used in Allen et al. (1996), an equilibrated shear wave is found analytically. The finite-amplitude behaviour of the analytic shear wave, including a forced second-harmonic correction to the mean alongshore current, and amplitude dispersion, agree well with the numerical results of Allen et al. (1996). Limitations in their numerical model prevent the development of a side-band instability. The stability of the equilibrated shear wave is demonstrated analytically. The analytical results confirm that the Allen et al. (1996) model correctly reproduces many important features of weakly nonlinear shear waves.

Nonlinear shear wave interaction in soft solids

2007 ◽  
Vol 122 (4) ◽  
pp. 1917-1926 ◽  
Author(s):  
Xavier Jacob ◽  
Stefan Catheline ◽  
Jean-Luc Gennisson ◽  
Christophe Barrière ◽  
Daniel Royer ◽  
...  
Keyword(s):  
Shear Wave ◽  
Wave Interaction ◽  
Soft Solids ◽  
Nonlinear Shear

Liver Elastography in Healthy Children Using Three Different Systems – How Many Measurements Are Necessary?

2020 ◽  
Author(s):  
Anders Batman Mjelle ◽  
Anesa Mulabecirovic ◽  
Roald Flesland Havre ◽  
Edda Jonina Olafsdottir ◽  
Odd Helge Gilja ◽  
...  
Keyword(s):  
Shear Wave ◽  
Transient Elastography ◽  
Intraclass Correlation ◽  
Age Groups ◽  
Liver Stiffness ◽  
Shear Wave Elastography ◽  
Healthy Children ◽  
Significant Difference ◽  
Pediatric Liver Disease ◽  
Liver Elastography

Abstract Purpose Liver elastography is increasingly being applied in screening for and follow-up of pediatric liver disease, and has been shown to correlate well with fibrosis staging through liver biopsy. Because time is of the essence when examining children, we wanted to evaluate if a reliable result can be achieved with fewer acquisitions. Materials and Methods 243 healthy children aged 4–17 years were examined after three hours of fasting. Participants were divided into four age groups: 4–7 years; 8–11 years; 12–14 years and 15–17 years. Both two-dimensional shear wave elastography (2D-SWE; GE Logiq E9) and point shear wave elastography (pSWE; Samsung RS80A with Prestige) were performed in all participants, while transient elastography (TE, Fibroscan) was performed in a subset of 87 children aged 8–17 years. Median liver stiffness measurement (LSM) values of 3, 4, 5, 6, 7, and 8 acquisitions were compared with the median value of 10 acquisitions (reference standard). Comparison was performed for all participants together as well as within every specific age group. We investigated both the intraclass correlation coefficient (ICC) with absolute agreement and all outliers more than 10 %, 20 % or ≥ 0.5 or 1.0 kPa from the median of 10 acquisitions. Results For all three systems there was no significant difference between three and ten acquisitions, with ICCs ≥ 0.97. All systems needed 4 acquisitions to achieve no LSM deviating ≥ 1.0 kPa of a median of ten. To achieve no LSM deviating ≥ 20 % of a median of ten acquisitions, pSWE and TE needed 4 acquisitions, while 2D-SWE required 6 acquisitions. Conclusion Our results contradict recommendations of 10 acquisitions for pSWE and TE and only 3 for 2D-SWE.

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