Fourier methods for harmonic scalar waves in general waveguides

Cosmological Waveguides for Gravitational Waves

We study the linearized equations describing the propagation of gravitational waves through dust. In the leading order of the WKB approximation, dust behaves as a nondispersive, non-dissipative medium. Taking advantage of these features, we explore the possibility that a gravitational wave from a distant source gets trapped by the gravitational field of a long filament of galaxies of the kind s...

Evaluation of Čerenkov Second Harmonic Generation in Planar Waveguides in the Fourier Domain

Analytical expressions for Čerenkov second-harmonic-generation in planar waveguiding structures are derived, based on evaluation of the conversion in the Fourier domain, assuming no depletion of the fundamental guided beam. The derivation is much shorter than that in existing methods and allows for a relatively simple interpretation of the main features.

Elastic waves in helical waveguides

Fourier Analysis of Multigrid Methods for General Systems of Pdes

Most iteration methods for solving boundary value problems can be viewed as approximations of a time-dependent differential equation. In this paper we show that the multigrid method has the effect of increasing the timestep for the smooth part of the solution leading back to an increase of the convergence rate. For the nonsmooth part the convergence is an effect of damping. Fourier analysis is ...

islanding detection methods for microgrids

امروزه استفاده از منابع انرژی پراکنده کاربرد وسیعی یافته است . اگر چه این منابع بسیاری از مشکلات شبکه را حل می کنند اما زیاد شدن آنها مسائل فراوانی برای سیستم قدرت به همراه دارد . استفاده از میکروشبکه راه حلی است که علاوه بر استفاده از مزایای منابع انرژی پراکنده برخی از مشکلات ایجاد شده توسط آنها را نیز منتفی می کند . همچنین میکروشبکه ها کیفیت برق و قابلیت اطمینان تامین انرژی مشترکان را افزایش ...