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...

Characterizing the wave field produced by an ultrasonic transducer is one important part of developing a complete measurement model of an ultrasonic NDE system. Within the paraxial approximation [1], this wave field can be expressed as a quasi plane wave field modified by a diffraction correction tenn to account for the 3-D effects of having a finite beam generated by the transducer. Previously...

Void detection is challenging due to the complexity of near-surface materials and the limited resolution of geophysical methods. Although multichannel, high-frequency, surfacewave techniques can provide reliable 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 resolution...

A detailed and comprehensive theoretical description of X-ray diffraction moiré fringes for a bicrystal specimen is given on the basis of a calculation by plane-wave dynamical diffraction theory. Firstly, prior to discussing the main subject of the paper, a previous article [Yoshimura (1997). Acta Cryst. A53, 810-812] on the two-dimensionality of diffraction moiré patterns is restated on a thor...

We discuss electron diffraction from two counterpropagating light waves with two different frequencies. We show that, even though these waves do not form a standing wave, electron diffraction similar to the conventional Kapitza-Dirac effect, i.e., scattering on a standing wave, is still possible. The nonlinear response of the electron to the laser fields creates a stationary diffraction grating...

An occulter is a large diffracting screen which may be flown in conjunction with a telescope to image extrasolar planets. The edge is shaped to minimize the diffracted light in a region beyond the occulter, and a telescope may be placed in this dark shadow to view an extrasolar system with the starlight removed. Errors in position, orientation, and shape of the occulter will diffract additional...

This paper is concerned with the diffraction of an electromagnetic wave by a perfectly conducting half-plane in a homogeneous bi-isotropic medium (asymptotically). Similar analysis in a source-free field is done in S. Asghar and A. Lakhtakia (1994), Planewave diffraction by a perfectly conducting half-plane in a homogeneous bi-isotropic medium. Int. J. Appl. Electromagnetics in materials, 5, (1...

Experiments were carried out in FY04 on detonation wave structure, detonation wave diffraction, and the fracture of thin-walled tubes by detonation waves. Computations were performed on detonation wave propagation and the elastic response of tubes to detonation loading. One new effort was initiated on the diffraction of detonation waves, and the other activities were a continuation of previous ...