Measurement of surface displacements resulting from acoustic wave propagation in solids has been used extensively in determining elastic properties of materials [1], [2]. Additionally, examination of acoustic wave propagation in materials has been used as a nondestructive tool in testing the integrity of structures, evaluating the size and position of bulk material defects, determining material...

The 2022 volcanic eruption in Tonga caused an unusually large tsunami around the Pacific. It travels with a faster apparent velocity and has larger amplitudes at long distances than what would be expected from conventional source. This was generated by moving atmospheric Lamb wave traveled speed of (0.31 km/s). Japanese data showed amplitude this first becomes small when approaching coast, due ...

Seismograms observed at Longmire, Washington, for four eruptions of Mt. St. Helens (May 18, June 13, August 7, and August 8, 1980), can be interpreted as Lamb pulses excited by a nearly vertical single force that represents the counter force of the eruption. These data provide reliable estimates of the impulse of the force K (time integral of the force) from which the total momentum and the kin...

doppler ultrasound can provide important information about vascular problems through the analysis of blood flow wave-form. the purpose of this study was obtaining the normal images of color doppler and estimation of blood flow velocity parameters of femoral artery in rabbits. left and right femoral arteries of 8 healthy adult new zealand rabbits were evaluated. color and spectral doppler images...

The model developed in this paper allows to predict the propagation of Lamb waves in an anisotropic wafer. More generally it can account for the linear dispersive propagation of scalar waves in an anisotropic and finite plate and for any local alteration in the displacement component of the Lamb Wave. The validation has been done using a solid-solid contact as an emitter-receiver.

Exact solutions of the time-dependent three-dimensional nonlinear vorticity equation for Euler flows with spherical geometry are provided. The velocity solution is sum a multipolar oscillatory function and rigid cylindrical motion swirl. oscillation mode whose radial angular dependencies given by Bessel functions vector harmonics, respectively. local frequency oscillations equals speed flow tim...

After an explosive eruption of the Hunga Tonga volcano on January 15, 2022, disturbances were observed at a distance about 12000km in Northern Tien Shan among variations atmosphere pressure, telluric current, and Doppler frequency shift ionospheric signal. At 16:00:55UTC pulse atmospheric pressure was detected there with peak amplitude 1.3hPa propagation speed 0.3056km/s, equal to velocity Lamb...

The aging world-wide aviation fleet requires methods for accurately predicting the presence of structural flaws that compromise airworthiness in aircraft structures. Nondestructive Evaluation (NDE) provides the means to assess these structures quickly, quantitatively, and noninvasively. Ultrasonic guided waves, Lamb waves, are useful for evaluating the plate and shell structures common in aeros...

The capability of embedded piezoelectric wafer active sensors (PWAS) to excite and detect tuned Lamb waves for structural health monitoring is explored. First, a brief review of Lamb waves theory is presented. Second, the PWAS operating principles and their structural coupling through a thin adhesive layer are analyzed. Then, a model of the Lamb waves tuning mechanism with PWAS transducers is d...

Introduction Compared to ultrasonic bulk waves that travel in infinite media with no boundary influence, guided waves require a structural boundary for propagation. As an example, some guided wave possibilities are illustrated in Figure 1 for a Rayleigh surface wave, a Lamb wave, and a Stonely wave at an interface between two materials.