نتایج جستجو برای: shear waves

تعداد نتایج: 181758  

A. Vakil and B. Firoozabadi,

Water-hammer is a transient condition which may occur in a network as a result of rapid or slow valve closures, pump failures, changes in turbine loading, etc. It creates high and low pressure waves which travel along the system and decay as a result of wall shear stress. Comparison o experimental and theoretical results revealed the failure of steady or quasi-steady models in correctly predict...

Journal: :Optics letters 2014
Sinan Li Yi Cheng Lipei Song Robert J Eckersley Daniel S Elson Meng-Xing Tang

Shear wave propagation provides rich information for material mechanical characterization, including elasticity and viscosity. This Letter reports tracking of shear wave propagation in turbid media by laser-speckle-contrast analysis. The theory is described, and a Monte Carlo simulation of light shear wave interaction was developed. Simulation and experiments on tissue-mimicking phantoms agree ...

2004
Nico F. Declercq Joris Degrieck Rudy Briers Oswald Leroy

Recently the authors have described the diffraction of horizontally polarized sound on periodically rough solid-liquid interfaces [Nico F. Declercq et al., IEEEUFFC 49(11), 1516-1521]. This has lead to the simulation of generated Love waves. This in combination with the theory of the diffraction of vertically polarized sound, where the generation of Scholte-Stoneley waves can be simulated, has ...

S Karmakar S Nirwal Sanjeev A Sahu,

An approach of Green’s function is adopted to solve the inhomogeneous linear differential equations representing wave equations in piezo-composite materials. In particular, transference of horizontally polarised shear (SH) waves is considered in bedded structure comprising of porous-piezo electric layer lying over a heterogeneous half-space. Propagation of SH-waves is considered to be influence...

2007
G. L. Brown

We examine the transmission of internal gravity waves through a non-uniformly stratified fluid with vertically varying background shear. To quantify wave transmission we show that the appropriate measure is the ratio of the flux of transmitted to incident pseudoenergy, T. We derive an analytic prediction of T for the transmission of waves through a piecewise-linear shear flow in two cases. In b...

2012
C. H. Cheng Y.

Direct determination of formation shear wave travel time is impossible in "slow" formations where the shear wave velocity is lower than the borehole fluid (mud) velocity. However, the Stoneley waves in these formations are very sensitive to changes in formation shear wave properties and can be used to indirectly determine the formation shear velocity, In addition, the P wave packet is highly de...

Journal: :Physics in medicine and biology 2015
Simon Chatelin Jean-Luc Gennisson Miguel Bernal Mickael Tanter Mathieu Pernot

The generation of shear waves from an ultrasound focused beam has been developed as a major concept for remote palpation using shear wave elastography (SWE). For muscular diagnostic applications, characteristics of the shear wave profile will strongly depend on characteristics of the transducer as well as the orientation of muscular fibers and the tissue viscoelastic properties. The numerical s...

Journal: :Physical review letters 2006
T A Carter B Brugman P Pribyl W Lybarger

An experimental investigation of nonlinear interactions between shear Alfvén waves in a laboratory plasma is presented. Two Alfvén waves, generated by a resonant cavity, are observed to beat together, driving a pseudomode at the beat frequency. The pseudomode then scatters the Alfvén waves, generating a series of sidebands. The observed interaction is very strong, with the normalized amplitude ...

Journal: :Physics in medicine and biology 2017
Kevin J Parker Juvenal Ormachea Fernando Zvietcovich Benjamin Castaneda

The determination of shear wave speed is an important subject in the field of elastography, since elevated shear wave speeds can be directly linked to increased stiffness of tissues. MRI and ultrasound scanners are frequently used to detect shear waves and a variety of estimators are applied to calculate the underlying shear wave speed. The estimators can be relatively simple if plane wave beha...

2009
Samuel N. Stechmann Andrew J. Majda

It is known that gravity waves in the troposphere, which are often excited by preexisting convection, can favor or suppress the formation of new convection. Here it is shown that, in the presence of wind shear or barotropic wind, the gravity waves can create a more favorable environment on one side of preexisting convection than the other side. Both the nonlinear and linear analytic models deve...

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