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21.
The spontaneous drift of the spiral wave in a finite domain in the complex Ginzburg-Landau equation is investigated numerically. By using the interactions between the spiral wave and its images, we propose a phenomenological theory to explain the observations. 相似文献
22.
23.
J. L. Hernández–Pastora O. V. Manko V. S. Manko J. Martín E. Ruiz 《General Relativity and Gravitation》2004,36(4):781-797
The extended quadruple–Kerr metric is used to consider equilibrium states of four collinear Kerr particles. We explain our previous failure to solve numerically the full set of the balance equations, and we derive a self–consistent system of the axis conditions leading to the equilibrium of all four constituents which can be black holes or hyperextreme objects. The equilibrium configurations obtained in this paper exhibit similar features with those occurring in the systems of two Kerr particles, for instance, the balance of four Kerr black holes with positive masses does not seem possible. Equilibrium states of two identical compound Kerr objects are also discussed. 相似文献
24.
聚芳香杂环甲烯的三阶非线性光学效应与时间分辨光克尔效应 总被引:6,自引:4,他引:2
合成了一系列聚芳香杂环甲烯,包括聚吡咯甲烯和聚噻吩甲烯.采用四波混频法研究材料的共振三阶非线性光学效应(λ=532nm),其共振二阶超分子极化率γ三阶非线性光学系数分别达到10-30esu和10-8esu.选择具有良好溶解性、成膜性的聚吡咯对二甲氨基苯甲烯(PPDMAB),采用飞秒时间分辨光克尔效应方法研究材料的非共振三阶非线性光学效应(λ=790nm).实验表明,翠绿亚胺碱溶液的光克尔信号仅表现一超快响应的成分,归功于π电子云扭转产生的非共振激发.PPDMAB的非共振二阶超分子极化率γ三阶非线性光学系数分别达到γ=5.78×10-32esu和χ(3)=1.26×10-10esu. 相似文献
25.
Akhlesh Lakhtakia 《Optik》2004,115(4):151-158
26.
Nonlinear susceptibility of a quantum dot (QD) embedded in a two-sided cavity, is studied theoretically from a weak-coupling to a strong-coupling regime. In the relevance of a quantum logic gate, the corresponding nonlinear phase shifts (Kerr effect) are estimated for coherent wavepackets including one photon on average. In the weak-coupling regime, the phase shift enhances strongly as a function of a coupling constant between the cavity photon and QD, and eventually saturates in the strong-coupling regime. We also show transmission spectra to evaluate the efficiency of the phase shift. Although the efficiency decreases monotonically in the weak-coupling regime, it rises in the strong-coupling regime. 相似文献
27.
Fiber-Optic Backscattering Profile Measurements for Determination of the Optical Coefficients of Turbid Media 总被引:1,自引:0,他引:1
A. M. Maiorova S. P. Kotova M. A. Rakhmatulin V. V. Yakutkin 《Journal of Russian Laser Research》2003,24(1):1-13
The necessity of using anisotropic approximation in techniques for determining optical parameters from the backscattered radiation profile is shown. A fiber-optic technique for simultaneous determination of the anisotropy parameter as well as the scattering and absorption coefficients of turbid media is proposed. It is based on the comparison of the experimental backscattered radiation profiles and those obtained by the numerical Monte Carlo method. 相似文献
28.
In this paper we prove the existence of a solution of a coupled system involving a two phase incompressible flow in the ground and the mechanical deformation of the porous medium where the porosity is a function of the global pressure. The model is strongly coupled and involves a nonlinear degenerate parabolic equation. In order to show the existence of a weak solution, we consider a sequence of related uniformly parabolic problems and apply the Schauder fixed point theorem to show that they possess a classical solution. We then prove the relative compactness of sequences of solutions by means of the Fréchet-Kolmogorov theorem; this yields the convergence of a subsequence to a weak solution of the parabolic system. 相似文献
29.
Zhang Tao 《中国科学G辑(英文版)》2007,50(5):591-600
The roles of the magnetic field and electric field of the light are investigated when the light is refracted in the medium.
The model of the electron cloud conductor is presented. Electron cloud in a molecule is treated as a conductor and the Faraday’s
Law is applied to this conductor that is in the alternating magnetic field of the light. dB
M/dt of the light gives rise to an alternating induced current on the electron cloud conductor, and the light exchanges energy,
i.e. the refractive energy, with the electron cloud conductor. Formulas of refractive index, which is the ratio of light speed
in vacuum to that in the medium, are derived with this model. These formulas are tested with several mediums and Langevin’s
diamagnetic susceptibility of helium gas, and the results are in good agreement with the measured data. The anisotropy and
the nonlinearity of the refractive index are explained with the theory described in this work.
Supported by Beijing Science and Technology New Star Program (Grant No. 952870400), the Beijing Municipal Commission of Education
and the Excellent Young Teachers Program of Ministry of Education of China 相似文献
30.
S.K. Mahapatra B.K. Dandapat 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,102(2):277-292
The current study addresses the mathematical modeling aspects of coupled conductive and radiative heat transfer in the presence of absorbing, emitting and isotropic scattering gray medium within two-dimensional square enclosure. A blended method where the concepts of modified differential approximation employed by combining discrete ordinate method and spherical harmonics method, has been developed for modeling the radiative transport equation. The gray participating medium is bounded by isothermal walls of two-dimensional enclosure which are considered to be opaque, diffuse and gray. The effect of various influencing parameters i.e., radiation-conduction parameter, surface emissivity, single scattering albedo and optical thickness has been illustrated. The adaptability of the present method has also been addressed. 相似文献