The orbit method and the Virasoro extension of Diff(S): I. Orbital integrals

Using the finite dimensional example of , the universal covering of PSU(1,1), as a guide, we revisit the orbit method as it applies to , the universal central extension of . We clarify some aspects of the classification of coadjoint orbits, determine boundedness properties of the natural height function on these orbits, and calculate orbital integrals.     

关于电磁学教学的三点建议

本文就电磁学教学中常遇到的问题谈一点教学体会。     

Influences of random disturbances on simultaneous resonances of nonlinear coupling systems

The influences of random disturbances on simultaneous resonances of nonlinear coupling systems are dealt with in this paper. First, the approximate probability distribution of behavior of nonlinear system is presented through using the stochastic averaging method. Secondly, using the Monte Carlo numerical simulation method, we study the above mentioned system. Both conclusions are nearly same. It is confirmed that the stochastic averaging method is one of efficient methods for dealing with nonlinear random vibration problems.     

Calculation of the spectral response of an arrayed-waveguide gating demultiplexer with a wide-angle beam propagation method in a cylindrical coordinate system

The spectral response of an arrayed-waveguide grating (AWG) demultiplexer is calculated by simulating the field propagation in the output section of an AWG with a wide-angle beam propagation method (BPM) in a cylindrical coordinate system. As in a practical design of an AWG demultiplexer, each output waveguide consists of two straight sections connected by a bending section. The spectral response obtained by the present algorithm is more accurate than those obtained with two popular approximate methods, namely, the conventional overlapped integral method and the standard BPM for radially straight and infinitely long output waveguides. With the present algorithm, the dependence of the spectral response on the parameters of the output section is analyzed. The channel crosstalk and the 3 dB passband width of the spectral response depend mainly on the length of the first straight section, the end separation and the angular separation of the output waveguides. The bending section results in an asymmetrical spectral response with remarkable sidelobes which can be reduced by increasing the bending radius.     

删失数据平滑非参数分位估计的Bahadur表示

本文讨论了在随机右删失情况下一种平滑非参数分位估计ｘｎ（ｐ）（ｘｎ（ｐ）是的解）．在一定的条件下获得了ｘｎ（ｐ）的Ｂａｈａｄｕｒ表示，作为推论获得了ｘｎ（ｐ）的渐近正态分布和重对数律．     

XGS—12型高速电影摄影机

XGS-12型摄影机是西安光机所新近推出的又一种16mm棱镜补偿式高速电影摄影机,其画幅尺寸为7.5×10.4mm~2时的最高拍摄频率为11000fps。该机性能优异,附件齐全,本文对该机将从光学系统摄影机和电控制系统三个部分加以介绍。     

一类中立型时滞微分方程解的渐近性

本文考虑一类非线性中立型时滞微分方程解的渐近性，给出了方程的解收敛于常数的结果．所得结论改进和推广了文献中的某些已知结果．     

稳恒磁场安培环路定理的一种证明

利用磁壳与线形闭合电流等效的证明方法，可避开使用矢量分析工具，一般地证明恒磁场安培环路定理。     

非均匀介质对强激光传播的影响

以强激光应用在化学工程中所遇到的物理问题为背景，研究介质的热透镜效应、吸收强弱、吸收饱和程度以及介质的流动等因素对激光传播的影响。根据一组简化模型，提出了描述光场行为的方程组，给出了不同情况下介质的温度分布情况、光线在介质中的变化行为以及激光光强的分布化情况。所得结果，对光化学工程设计有一定的参考价值。