A new far-field closure condition for a CFD-based numerical wave tank that uses a potential wave solution to overlay the outer computational domain of a CFD solution is described. A prescribed potential wave solution covers the region beyond a diameter more than 10 times of floater footprints. The diffracted waves from the body are absorbed by the ‘potential-attractor’ terms applied in the inte...

Time-of-flight diffraction method (ToFD) is an amplitude-independent sizing method which is based on the measurement of time-of-flight of defect tip diffracted waves. Although ToFD can measure through-wall length of defect accurately, this method is not capable of measuring horizontal defect size. In this paper, a new ToFD method for evaluating horizontal planar defects is presented. The finite...

An x-ray-diffraction method that directly senses the phase of the structure factor is demonstrated and used for determining the local polarity of thin ferroelectric films. This method is based on the excitation of an x-ray standing-wave field inside the film as a result of the interference between the strong incident x-ray wave and the weak kinematically Bragg-diffracted x-ray wave from the fil...

TOFD technique is based on diffraction of ultrasonic waves on the tips of discontinuities instead of reflection on the interface of discontinuities. When ultrasound is incident at linear discontinuities such as crack diffraction takes place at its extremities in addition to the usual reflected wave. The diffracted energy is emitted over a wide angular range, presumed to originate at the extremi...

A quasi-collinear and partially degenerate four-wave mixing model is proposed to explain the optical phase-conjugation property of various types of stimulated backscattering. According to this model, after passing through a phase-disturbed medium or an aberration plate, the input pump beam can be resolved into two portions: a stronger undisturbed regular portion and a weaker phase-disturbed irr...

The thin-film x-ray standing wave ~XSW! technique is used for an atomic-scale study of polarization switching in ferroelectric Pb~Zr0.3Ti0.7!O3 ~PZT!/electrode heterostructures grown on SrTiO3(001). The XSW is selectively generated in the PZT by the interference between the incident x-ray wave and the weak ~001! Bragg diffracted wave from the film. The XSW excites a fluorescence signal from the...

The geometrical diffraction theory, in the sense of Keller, is here reconsidered as an obstacle problem in the Riemannian geometry. The first result is the proof of the existence and the analysis of the main properties of the diffracted rays, which follow from the non-uniqueness of the Cauchy problem for geodesics in a Riemannian manifold with boundary. Then, the axial caustic is here regarded ...

This paper addresses the need to know the unsteady forces and moments on an underwater vehicle in finite depth water, at small enough submergences for it to be influenced by sea waves. The forces are those due to the waves themselves as well as the radiation forces due to unsteady vehicle motions. Knowledge of these forces and the mass distribution of the vehicle allow solution of the equations...