短脉冲强激光在稀薄等离子体中传播时的电磁类孤立子

 采用二维粒子模拟方法，研究了短脉冲强激光在稀薄等离子体中传播时电磁类孤立子的产生和时空演化过程。通过分析电磁场与等离子体波的非线性能量交换和激光场的频率谱结构等，给出了电磁类孤立子形成的基本物理图像，讨论了等离子体参数对电磁类孤立子形成的影响。模拟结果表明：类孤立子的形成是由于局部电磁波振荡频率减小至等离子体频率引起的，初始等离子体密度越高越容易形成空间局域结构。     

A second order numerical scheme for the solution of the one-dimensional Boussinesq equation

A predictor–corrector (P-C) scheme is applied successfully to a nonlinear method arising from the use of rational approximants to the matrix-exponential term in a three-time level recurrence relation. The resulting nonlinear finite-difference scheme, which is analyzed for local truncation error and stability, is solved using a P-C scheme, in which the predictor and the corrector are explicit schemes of order 2. This scheme is accelerated by using a modification (MPC) in which the already evaluated values are used for the corrector. The behaviour of the P-C/MPC schemes is tested numerically on the Boussinesq equation already known from the bibliography free of boundary conditions. The numerical results are derived for both the bad and the good Boussinesq equation and conclusions from the relevant known results are derived.      

在三通道α-螺旋蛋白质中传递生物能量的孤子的特性

用庞小峰先生提出的生物能量传递的新理论和 Runge-Kutta数值模拟方法,研究了三通道α-螺旋蛋白质中激发的孤子的动力学特性,求出在0K和300K温度下该孤子稳定地沿蛋白质链传递.由此可见,它能担任在蛋白质分子中传递生物能量的功能.从而再次证实了新理论的可利用性.     

Soliton experiments in stimulated Raman scattering

Experimental observations of solitons in stimulated Raman scattering are reported. Soliton formation resulted from the introduction of a phase shift in the incident Stokes beam as predicted by theory. Pulse sharpening and retardation on propagation in the Raman medium have been observed along with amplitude diminution. The first two features were predicted and the third was not. Spontaneous soliton formation has been observed in the absense of any amplitude modulation or apparent phase shift in the optical fields, indicating that additional sets of initial conditions may result in soliton formation.Work performed under the auspices of the U.S. Department of Energy.     

Solitons and Bäcklund transformation for a generalized (3+1)-dimensional variable-coefficient B-type Kadomtsev–Petviashvili equation in fluid dynamics

Under investigation in this paper is a generalized (3+1)-dimensional variable-coefficient B-type Kadomtsev–Petviashvili equation, which describes the propagation of nonlinear waves in fluid dynamics. Bilinear form and Bäcklund transformation are derived by virtue of the Bell polynomials. Besides, the one- and two-soliton solutions are constructed via the Hirota method.     

Multiple bright and dark soliton solutions in three component spinor Bose-Einstein condensates

We investigate a quasi one dimensional spin-1 Bose-Einstein Condensates (BEC) in the absence of an external confinement governed by a system of three coupled Gross-Pitaevskii (GP) equation. Based on the Lax-pair, we construct one soliton solution employing gauge transformation method. In addition, the multiple bright and dark soliton solutions are obtained by properly choosing amplitude dependent parameter in the Lax-pair. The results of the paper emphasizes the richness in the structure of soliton solutions admitted by the spin components, a phenomenon which has never been brought out to the fore. We have also extended the gauge transformation method to generate two soliton solutions.     

实现20Gbit/s的OTDM孤子信号56km色散位移光纤的传输

在国内最先采用孤子的方式将8×2.5Gb/s的OTDM信号在色散位移光纤中传输了56.1km,对8×2.5Gb/s的OTDM进行解复用后进行了误码测量,系统功率代价为2.9dB.系统采用增益开关半导体激光器作光孤子源,高Q电滤波方式提取时钟,非线性光学环路镜解复用。孤子脉冲最大半宽度为20ps,传输光纤平均色散1.2ps/nm/km。     

A Petrov-Galerkin method for equal width equation

The equal width equation is solved numerically by Petrov-Galerkin method using linear hat function and quadratic B-spline function as trial and test functions respectively. Product approximation has been used in this method. A linear stability analysis of the scheme is shown to be conditionally stable. Test problems including the single soliton and the interaction of solitons are used to validate the suggested method, which is found to be accurate and efficient. The Maxwellian initial condition pulse and the development of an undular bore are also studied.     

电子在蛋白质分子中的迁移机理及其特性

ATP水解作用所释放的能量能引起蛋白质分子中额外电子的激发,其激发与氨基酸残基晶格畸变相互作用,使额外电子自陷成孤子,这孤子在附着有供体(D)和受体(A)的蛋白质分子中运动时,由于孤子与供体电子的相互作用而"自局域"在孤子上进行迁移,从而可把电子供给受体.使用作者提出的孤子理论研究了这种迁移的特征,计算了在这种非平衡态过程中由孤子迁移电子的速率和动能系数,得到了一些有趣的结果,揭示了这种迁移的本质,求得了迁移的大小.     

Study of nonlinear dissipative pulse propagation under the combined effect of two-photon absorption and gain dispersion: A variational approach involving Rayleigh’s dissipation function

We try to derive some explicit equations for predicting the laws which govern the evolution of different parameters of a propagating optical pulse in a nonlinear medium under the combined influence of two-photon absorption and gain dispersion. Using the generalized Euler-Lagrange equation, the dynamics of different pulse parameters are generated. The Rayleigh’s dissipation function is incorporated in order to take recourse to the dissipative part, with an analogy with the non-conservative frictional problem in classical mechanics. It appears from the study that the influence of the dissipative part can well be explained using the proposed model. The analytically predicted results are compared with the numerical data obtained from direct simulation of the Ginzburg-Landau equation and the results are found to be quite satisfactory, supporting the prediction.