[1] The unusual reactivation of the North China Craton (NCC) challenges the classical views concerning the strength and stability of cratonic lithosphere. By using teleseismic body-waves recorded at 250 seismic stations, this paper presents high-resolution North China Models of Pand S-wave velocity based on finite-frequency kernel tomography. Both Pand S-wave velocity models reveal that: (1) an...

Apparent phase velocities in the main pulmonary artery were calculated from simultaneous measurements of pressure at two sites in 11 anesthetized, open-chest dogs, at heart rates ranging from 24 to 240 beat/min. The distribution of apparent phase velocity with harmonic frequency was similar to that reported previously for input impedance and frequency. Phase velocity in the absence of reflectio...

A thin low-velocity layer that continues from the surface down to at least 135 km depth has been detected within the subducted slab through the analysis of a three-component short-period set of digital data from seismic stations in southern Taiwan. Two distinct phases in the first few seconds of the P-waves generated by nine intermediate-depth earthquakes are observed at one station (TAW) locat...

In the electromagnetic theory, the vacuum impedance Z0 is a universal constant, which is as important as the velocity of light c0 in vacuum. Unfortunately, however, its significance is not appreciated so well and sometimes the presence itself is ignored. It is partly because in the Gaussian system of units, which has widely been used for long time, Z0 is a dimensionless constant and of unit mag...

Piezoelectric wafer active sensors can be applied to aging aircraft structures to monitor the onset and progress of structural damage such as fatigue cracks and corrosion. Two main detection strategies are considered: (a) the wave propagation method for far-field damage detection; and (b) the electro-mechanical (E/M) impedance method for near-field damage detection. These methods are developed ...

Velocity measurement errors were investigated for an array-based preclinical ultrasound scanner (Vevo 2100, FUJIFILM VisualSonics, Toronto, ON, Canada). Using a small-size rotating phantom made from a tissue-mimicking material, errors in pulse-wave Doppler maximum velocity measurements were observed. The extent of these errors was dependent on the Doppler angle, gate length, gate depth, gate ho...

pore pressure is an important parameter, in exploration and production of hydrocarbon resources. lack of accurate knowledge about pore pressure, before drilling phase, leads to serious dangers in drilling process. accurate knowledge about distribution of pore pressure in a field, leads to reduce risks in drilling, improve well planning and mud weight calculations. during burial, normally pressu...

In atmospheric acoustics, the subject of surface waves has been an area of discussion for many years. The existence of an acoustic surface wave is now well established theoretically. The mathematical solution for spherical wave propagation above an impedance boundary includes the possibility of a contribution that possesses all the standard properties for a surface wave. Surface waves exist whe...

Void detection is challenging due to the complexity of near-surface materials and the limited resolution of geophysical methods. Although multichannel, high-frequency, surface-wave techniques can provide reliable shear (S)-wave velocities in different geological settings, they are not suitable for detecting voids directly based on anomalies of the S-wave velocity because of limitations on the r...

An improved single sided Rayleigh wave (R-wave) measurement was suggested to characterize surface breaking crack in steel reinforced concrete structures. Numerical simulations were performed to clarify the behavior of R-waves interacting with surface breaking crack with different depths and degrees of inclinations. Through analysis of simulation results, correlations between R-wave parameters o...