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952.
提出大调制度下光擦除双光束耦合两级放大的中间段理论,在这种条件下,耦合波方程只能进行数值求解,并将该理论和其他几种理论的结果进行了比较。 相似文献
953.
We have solved a self-consistent problem on interaction of two dipole atoms located at an arbitrary distance from each other
with the field of a quasiresonance light wave, whose intensity is sufficient for the system to manifest nonlinear properties.
The atoms are considered as two-level systems described by means of Bloch optical equations, while the field inside of the
system includes both Coulomb and retarded parts. We consider a situation where atoms are identical and the distance between
them is much smaller than the length of an outer light wave. The distribution of an electric field both inside of a small
object and outside of it is found numerically. It is shown that the amplitude of the electric field in a wave zone depends
substantially on the frequency of the external field and interatomic distance, while the field distribution differs from the
field pattern of an electric dipole. At definite values of the external field intensity an optical multistability is a feature
of the system under investigation. We have elucidated the conditions under which the multistability is manifested in the present
system. The results obtained are considered as the near-field effect in the optics of small objects, which makes it possible
to investigate the structure of small objects by means of optical radiation.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 3, pp. 375–378, May–June, 2000.
The present work was supported by the Russian Foundation for Fundamental Research (grant 98-02-16035) and by a grant from
the Federal Purpose-Oriented Program “Integration.” 相似文献
954.
考虑了有界区域上一类非线性退化波动方程的初边值问题.通过改进Vitillaro,Li和Tsai的方法,建立了非正的初始能量以及正的初始能量下解的爆破结果.同时,还给出了解的生命跨度估计. 相似文献
955.
ZHANG Huan ;TIAN Bo ;ZHANG Hai-Qiang ;GENG Tao ;MENG Xiang-Hua ;LIU Wen-Jun ;CAI Ke-Jie 《理论物理通讯》2008,50(11):1169-1176
For describing various complex nonlinear phenomena in the realistic world, the higher-dimensional nonlinear evolution equations appear more attractive in many fields of physical and engineering sciences. In this paper, by virtue of the Hirota bilinear method and Riemann theta functions, the periodic wave solutions for the (2+1)-dimensional Boussinesq equation and (3+1)-dimensional Kadomtsev Petviashvili (KP) equation are obtained. Furthermore, it is shown that the known soliton solutions for the two equations can be reduced from the periodic wave solutions. 相似文献
956.
基于弹性波散射对二维障碍物边界的识别 总被引:1,自引:0,他引:1
给出了二维障碍物弹性波散射场的一种近似积分形式 ,基于 Fourier变换法建立了均匀障碍物特征函数与其远场散射振幅中形状因子的关系式 ,最后就基体为锌 ,对圆形和椭圆形截面铁夹杂进行了计算机模拟 ,结果表明该反演方法对定量无损检测技术具有应用价值。 相似文献
957.
The long-time behaviour of spectral semi-discretisations of weakly non-linear wave equations is analysed. It is shown that
the harmonic actions are approximately conserved for the semi-discretised system as well. This permits to prove that the energy
of the wave equation along the interpolated semi-discrete solution remains well conserved over long times and close to the
Hamiltonian of the semi-discrete equation. Although the momentum is no longer an exact invariant of the semi-discretisation,
it is shown to be approximately conserved. All these results are obtained with the technique of modulated Fourier expansions.
Dedicated to Professor Arieh Iserles on the Occasion of his Sixtieth Birthday. 相似文献
958.
959.
The propagation of phonons in one-dimensional quasicrystals is investigated. We use the projection method which has been recently proposed to generate almost periodic tilings of the line. We define a natural Laplace operator on these structures, which models phonon (and also tight-binding electron) propagation. The selfsimilarity properties of the spectrum are discussed, as well as some characteristic features of the eigenstates, which are neither extended nor localized. The long-wavelength limit is examined in more detail; it is argued that one is the lower critical dimension for this type of models. 相似文献
960.
In this paper, we propose a high order Fourier spectral-discontinuous Galerkin method for time-dependent Schrödinger–Poisson equations in 3-D spaces. The Fourier spectral Galerkin method is used for the two periodic transverse directions and a high order discontinuous Galerkin method for the longitudinal propagation direction. Such a combination results in a diagonal form for the differential operators along the transverse directions and a flexible method to handle the discontinuous potentials present in quantum heterojunction and supperlattice structures. As the derivative matrices are required for various time integration schemes such as the exponential time differencing and Crank Nicholson methods, explicit derivative matrices of the discontinuous Galerkin method of various orders are derived. Numerical results, using the proposed method with various time integration schemes, are provided to validate the method. 相似文献