نتایج جستجو برای: rayleigh
تعداد نتایج: 15031 فیلتر نتایج به سال:
We study the localization of Rayleigh waves propagating in a semi-infinite and isotropic medium with inhomogeneities that are modeled as rods parallel to the incoming wave front and are distributed randomly up to a maximum depth. For a perfectly smooth surface, the localization length of a Rayleigh wave is predicted to reach a minimum at intermediate wavelength l and to diverge for both low and...
The accuracy and physical significance of the classical Rayleigh-Sommerfeld and Kirchhoff diffraction integrals are assessed in the context of Sommerfeld's rigorous theory of half-plane diffraction and Maxwell's equations. It is shown that the Rayleigh-Sommerfeld integrals are in satisfactory agreement with Sommerfeld's theory in most of the positive near zone, except at sub-wavelength distance...
In this paper, we look for non-uniform Rayleigh beams isospectral to a given uniform Rayleigh beam. Isospectral systems are those that have the same spectral properties, i.e. the same free vibration natural frequencies for a given boundary condition. A transformation is proposed that converts the fourth-order governing differential equation of non-uniform Rayleigh beam into a uniform Rayleigh b...
Software reliability modeling and prediction are important issues during software development, especially when one has to reach a desired reliability prior to software release. Various techniques, both static and dynamic, are used for reliability modeling and prediction in the context of software risk management. The single-phase Rayleigh model is a dynamic reliability model; however, it is not...
The fast transmission power control problem in a cellular network is studied when the signal attenuation is subject to a fast time-varying multipath Rayleigh fading. An asymptotic representation of the link gain evolution in time is first derived, and then used for constructing a Fast Time Variant distributed constrained Power Control (FTVPC). The proposed FTVPC power control successfully count...
by growing the population and need for settlement, many cities have been built on soft sediments and seismic areas. it emphasizes the need for a careful and reliable assessment of site effect phenomena. beyond the methods of studying site effects, microtremor recordings has become popular over the last decades as it offers a convenient, practical and low cost tool to be used in urbanized areas....
We prove a new upper bound on the vertical heat transport in Rayleigh-Bénard convection of the form c Ra 1 3 (lnRa) 2 3 under the assumption that the ratio of Prandtl number over Rayleigh number satisfies Pr Ra ≥ c0 where the non-dimensional constant c0 depends on the aspect ratio of the domain only. This new rigorous bound agrees with the (optimal) Ra 1 3 bound (modulo logarithmic correction) ...
Ultrasonic testing for fatigue crack detection in metallic members are commonly performed using time domain analysis of Rayleigh waves. This approach will be successful only if the fatigue cracks produce strong interaction with the Rayleigh waves. The optimum frequency range of ultrasonic Rayleigh waves for scanning long structural members in the field is from 0.5 to 2.25 MHz because higher fre...
Laser guide stars created by Rayleigh scattering provide a reasonable means to monitor atmospheric wavefront distortions for real-time correction by adaptive optics systems. Because of the l 4 wavelength dependence of Rayleigh scattering, short-wavelength lasers are a logical first choice for astronomical laser guide star systems, and in this paper we describe the results from a sustained exper...
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