Internal gravity waves are generated in a stratified fluid by arbitrary forced oscillations of a horizontal disc. The wave fields are calculated in both the time domain and the frequency domain. In the time domain, an initial-value problem is solved using Laplace transforms; causality is imposed. In the frequency domain (time-harmonic oscillations), a radiation condition is imposed: a plane-wav...

Communicated June 30, 1964 The problem of the diffraction of obliquely incident scalar waves by finite slits and strips with various boundary conditions has been considered previously.' Reference may be made to the work of other authors on the diffraction of scalar waves by finite slits.2 The problem of the diffraction of obliquely incident vector elastic waves by a clamped finite strip has als...

We propose a numerical-asymptotic boundary element method for problems of time-harmonic acoustic scattering of an incident plane wave by a soundsoft two-dimensional (2D) screen. Standard numerical schemes have a computational cost that grows at least linearly with respect to the frequency of the incident wave. Here, we enrich our approximation space with oscillatory basis functions carefully de...

This paper uses a method for shape reconstruction of a 2-D homogeneous object with arbitrary geometry and known electrical properties. In this method, the object is illuminated by a Gaussian pulse, modulated with sinusoidal carrier plane wave and the time domains’ footprint signal due to object presence is used for the shape reconstruction. A nonlinear feedback loop is used to minimize the diff...

We develop an efficient numerical method for analyzing second harmonic generation (SHG) in two-dimensional photonic crystals composed of nonlinear circular cylinders embedded in a linear background medium. Instead of solving the governing inhomogeneous Helmholtz equation for the second harmonic wave in the entire structure directly, we define and solve a locally generated second harmonic field ...

In order to enhance torque density of five-phase permanent magnetic synchronous motor with third harmonic injection for electric vehicles (EVs) applications, optimum seeking method for injection ratio of third harmonic was proposed adopting theoretical derivation and finite element analysis method, under the constraint of same amplitude for current and air-gap flux. By five-dimension space vect...

A method of complex orthogonal decomposition is summarized for the time-domain, and then formulated and justified for application in the frequency-domain. The method is then applied to the extraction of modes from simulation data of sampled multi-modal traveling waves for estimating wave parameters in one-dimensional continua. The decomposition is first performed on a transient nondispersive pu...

For second harmonic generation in two-dimensional wave-guiding structures composed of segments that are invariant in the longitudinal direction, we develop an efficient numerical method based on the Dirichlet-to-Neumann (DtN) maps of the segments and a marching scheme using two operators and two functions. A Chebyshev collocation method is used to discretize the longitudinal variable for comput...