A broad line n.m.r. study of oriented poly(vinylidene fluoride)

Broadline nuclear magnetic resonance measurements have been carried out for the proton resonance in oriented poly(vinylidene fluoride). The spectra in general show two component lines with distinctly different line widths. The broad component shows a high degree of molecular orientation and can be satisfactorily assigned to the crystalline regions of the polymer. The narrow component corresponds to an oriented non crystalline phase which is sufficiently constrained to allow motion about the chain axis only. An appreciable decrease in the value of the rigid mass fraction was observed in both of the samples over the temperature range examined. Our calculations indicate that this could play an important role in the temperature dependence of the pyroelectric response of this material.     

分布式光纤喇曼放大技术及其在WDM系统中的应用

介绍了分布式光纤喇曼放大技术的原理、特点和应用 ,并从受此影响的 WDM传输系统的信噪比、噪声指数和品质因数三个方面讨论了光纤喇曼放大技术在提升光纤通信系统性能方面的重要作用。     

有耗传输线的TLM模型法

本文从传输线理论出发，介绍了一种解决传输线问题的新方法－－TLM法。     

编码解码芯片HD3-6408-9及其应用

编码解码芯片HD3 64 0 8 9是一种高性能的CMOS器件。这种大规模芯片主要由编码器和解码器两部分组成。在数据传输应用中 ,采用两个独立的单片机系统 ,利用编码解码芯片 (HD3 64 0 8 9)组成数字信号的接收、发送及显示部分来完成数据传输功能     

Discrete singular convolution and its application to the analysis of plates with internal supports. Part 2: Applications

Part 2 of this series of two papers presents the applications of the discrete singular convolution (DSC) algorithm. The main purpose of this paper is to explore the utility, test the accuracy and examine the convergence of the proposed approach for the vibration analysis of rectangular plates with internal supports. Both partial internal line supports and complex internal supports are considered for 21 square plates of various combinations of edge support conditions. The effects of different size, shape and topology of the internal supports and different boundary conditions on the vibration response of plates are investigated. The partial internal line supports may vary from a central point support to a full range of cross or diagonal line supports. Several closed‐loop supports, such as ring, square and rhombus, and their combinations are studied for complex internal supports. Convergence and comparison studies are carried out to establish the correctness and accuracy of the DSC algorithm. The DSC results are compared with those in the available literature obtained by using other methods. Numerical results indicate that the DSC algorithm exhibits controllable accuracy for plate analysis and shows excellent flexibility in handling complex geometries, boundary conditions and support conditions. Copyright © 2002 John Wiley & Sons, Ltd.     

长距离钢带传动的张紧机构设计与应用

比较了几种长距离传动方式的特点与适用场合，重点探讨了实现长距离精密传动的技术要点。结合实际工程，完成了长距离钢带精密传动的应用，并指出张紧机构的设计与应用是钢带实现长距离精密传动的关键。为此文中对钢带传动的典型张紧机构进行了比较，并分析了这几类张紧机构的应用情况，有参考和应用价值。     

I/OIMAGESYSTEM微波中继应用

微波中继的应用非常广泛 ,目前在二维、三维施工中跨越障碍物时 ,一般都使用微波中继站来传输命令和数据。文章就微波中继及I/OIMAGESYSTEM“蛇形排列”先进功能的实际应用进行了详细的阐述 ,同时提出了使用微波中继站应注意的问题。     

一种联合信源信道匹配的视频传输方法

介绍了一种实现联合信源-信道编码的通用的新方法—联合信源-信道匹配。该方法思想巧妙,通过将有限的通信系统资源在信源和信道编码器之间进行巧妙合理的分配,从而获得最优的系统整体传输性能。并且,该方法并不仅局限于特定的信源-信道编码器对,可适用于任何一种信源-信道编码器对共享有限系统资源的情况,具有很好的通用性。仿真实验证明了JSCM通用视频传输系统能获得比传统的固定码率分配系统更高的整体性能增益。     

浅谈小鹤立河水库兴利调度图的编制

针对小鹤河水库来水情况及需水要求，确定该水库调节方式为多年调节，通过该水库兴利规划调度原则进行长系列法多年调节计算，依据选定的兴利调节计算结果，绘制水库兴利调度图，供水库管理部门在水库运行期间正确调度运用，合理利用水起到指导作用。     

适用于快速平台测井的多通道核能谱测井仪设计

介绍一种基于快速平台测井要求的多通道核能谱测井仪设计方案。复杂可编程逻辑器件的应用使仪器功能增强，规模减小。该系统可对岩性密度长短源距脉冲信号、自然γ能谱脉冲信号进行多道脉冲幅度分析，并对补偿中子测井信号及井下多路常规模拟信号、脉冲信号进行数字化采集。数据传输采用曼彻斯特编码，传输方式可选择20kB／s半双工(兼容Atlas 3508)或下行20kB／s、上行41．66或93．75kB／s全双工方式(兼容Atlas WTS)，适应挂接到不同测井系统的需要。