京—汉—广架空光缆工程

本文介绍我国第一条国产长途光缆一级通信干线京—汉—广架空光缆工程系统的构成,并侧重介绍京—汉—广工程的光传输系统和传输设备。     

单模光纤中光脉冲啁啾的分析

论述了啁啾光脉冲在单模光纤中传输时啁啾和脉宽的变化，以及此变化与相应的频谱相位变化的关系．详细分析了啁啾变化的规律，并讨论了其物理图像及该规律在光纤通信中的应用．实验中所获得的脉宽变化与理论计算相符。     

双绞传输线电磁兼容特性的FDTD分析

将曲线坐标系中的时域有限差分法（FDTD）拓展到空间为任意媒质情形，然后针对双绞传输线的特殊结构综合运用曲线坐标系、圆柱坐标系、旋转坐标系和子域连接法进行空间网格划分、FDTD建模，并通过求解双绞传输线和平行传输线的特性阻抗对该建模的准确度进行了验证，最后在空间线源激励下对双绞线和平行线的电磁兼容特性进行了比较，可以看出双绞线对空间电磁场的耦合能力远远低于平行线。     

微机械传输线的毫米波应用

以几种典型的毫米波波段微机械传输线结构为研究对象，讨论了近几年的最新研究成果，包括微带、带状线、开放和封闭的共面波导。微机械传输线能够充分降低介质损耗，具有传输损耗小、工作频带宽、色散小、制作工艺能与传统集成电路工艺兼容等特点，是毫米波波段平面集成传输线应用的首选技术方案，同时微机械传输线的出现为毫米波单片集成电路以及毫米波系统的微型化提供了解决方案。     

基于嵌入式LINUX的GPRS数据传输系统

简要分析了嵌入式Linux操作系统和GPRS传输原理，并结合嵌入式Linux技术和GPRS网络，提出基于嵌入式Linux操作系统的GPRS数据传输系统设计方法。目前，中国移动的GPRS网络运行稳定且支持TCP／IP协议，Linux内核也支持此协议栈，这样以很少的投入就可以开发出满足不同需要的GPRS数据传输应用。     

几种新型无线图像传输方式的比较

详细讨论几种利用CDPD网络和专用无线modem以及无线通信设备传输图像的新型无线图像传输方式,并比较了各种方式的优缺点。     

相位共轭法解决光纤传输中的信号失真

光纤传输过程中所引起的信号失真有很多补偿方法,本文对其中的相位共轭法进行了理论推导和分析。     

Mean Field Method with Different Dispersion Maps for WDM Systems

Using mean field method proposed in Ref. [4], the 40 Gb/s multi--channel WDM optical fiber transmission systems with different dispersion maps are simulated. By this method, the computation time can be greatly reduced since following only the full time evolution of a limited number of channels while treating the other ehannels as continuous wave. But since dispersion plays an important role in the process of FWM and XPM,different dispersion maps will affect the application of the method. The dependence of the method on dispersion maps is investigated. The results not only confirm the mean field method,but also give useful approach for system design.     

Focusing of electromagnetic waves into a uniaxial crystal

We derive integral representations suitable for studying the focusing of electromagnetic waves through a plane interface into a uniaxial crystal. To that end we start from existing exact solutions for the transmitted fields due to an arbitrary three-dimensional (3D) wave that is incident upon a plane interface separating two uniaxial crystals with arbitrary orientation of the optical axis in each medium. Then we specialize to the case in which the medium of the incident wave is isotropic and derive explicit expressions for the dyadic Green's functions associated with the transmitted fields as well as integral representations suitable for asymptotic analysis and efficient numerical evaluation. Relevant integral representations for focused 3D electromagnetic waves are also given. Next we consider the special case in which (i) the incident field is a two-dimensional (2D) TM wave and (ii) the optical axis in the crystal lies in the plane of incidence, implying that we have a 2D vectorial problem, and derive dyadic Green's functions, integral representations suitable for asymptotic and numerical treatment, and integral representations for focused TM fields. Numerical results for focused 2D TM fields based on these integral representations as well as corresponding experimental results will be presented in forthcoming papers.     

Reflection and transmission of obliquely incident Rayleigh surface waves by a viscoelastic interphase

The reflection and transmission of obliquely incident Rayleight surface waves by an interphase between two quarter spaces of identical or different materials, have been investigated. The mechanical behavior of the interphase is represented by a thin viscoelastic layer. By using the full space Green's functions due to a spatially harmonic line load, the mathematical statement of the 3-dimension problem is reduced to a 2-dimension system of singular integral equations. The far-field behavior of the scattered waves leads to the definition of reflection and transmission coefficients,R andT. The system of the singular integral equations are solved forR andT with the boundary element method. The results are presented for selected values of the elastic constants of the joined quarter spaces, the parameters of the interphase and the incident angles of Rayleigh surface waves.