On the Mavroyannis–Stephen relativistic long-range interaction energy term between optically active molecules

The relativistic long-range intermolecular interaction energy term of Mavroyannis and Stephen is estimated for some amino acids by using optical rotatory dispersion data and for hexahelicene by using theoretical values of excitation energies and rotational strengths. The result shows that the interaction energy may be significant for the interaction between some essentially dissymmetric chromophores such as hexahelicene, but that it is unimportant for other cases.     

基于微分干涉仪的新型光纤声传感器

基于微分干涉仪原理，建立了一套新型光纤声传感器系统。对该系统进行了理论分析，建立了系统的数学模型，推导并分析了干涉仪的输出信号，并以宽频信号做声源进行了实验研究。实验结果与理论分析相吻合，解决了目前双干涉仪线性范围窄的问题，简化了信号处理电路，可使用低相干光源，并且系统不受外界缓变因素的影响，对宽频声源定位的误差小于1％。     

两种航空电子光纤统一网络标准的比较及结合

根据美军最新一代战斗机研制计划提出的"航空电子光纤统一网络"的概念,从拓扑结构、可扩展性和机载应用等方面对FC和SCI两种航空电子光纤统一网络标准进行了比较.根据比较的结果,探索了综合使用两者的模型.     

光纤光栅传感器信号解调方法综述

当光纤光栅传感器上的温度或应力发生变化时,布拉格反射波长也随之发生漂移,根据这个漂移量便可判断待测量大小,因此,人们提出了许多解调方法.文章论述了几种常用的光纤光栅传感器信号解调方法,分类评述了这几种方法的工作原理和性能,分别给出了其典型的实验原理图,并对其优点和缺点进行了分析比较.     

Feasibility study of the application of voltage contrast to printed circuit board

Voltage contrast (VC) has been a powerful tool for the failure analysis of integrated circuits and multichip module. As the packing density of printed circuit board (PCB) is increasing, conventional failure analysis methods to detect open or short circuit in PCBs are no longer adequate, and voltage contrast method could be a method for this purpose. However, unlike the cases of integrated circuits and multichip module, there are many areas in PCB that will produce serious charging effect when examine under the scanning electron microscope. One of the areas is the presence of solder mask on PCB.This work examines the feasibility of using voltage contrast for PCB failure analysis. Specially designed PCB is used for experimentation, and it is found that positive bias on one track and zero bias on another copper track provide a better image contrast as compared to negative and zero biases on the tracks. Also, the variation of the image contrast with different spacing between inter copper tracks has studied. It is found that the variation depends on the presence of solder mask and its location. The variation can be very different for negative bias case as compared to the positive bias case.Finite element analysis is also performed to explain the experimental observations. All the observations can be well explained by the charging effect of the solder masks. The charging effect of solder mask is indeed very significant in affecting the image contrast, and it could reduce the contrast to almost zero in some cases.     

一种改进的夜视图像增强处理算法

图像增强是夜视图像处理的一种重要方法,而直方图均衡是最经典的图像增强算法之一.但将它直接用于夜视图像处理有如下缺点:(1)丢失原始图像的亮度信息;(2)处理过程中有灰度合并现象发生.结合夜视图像的特点,提出了一种保持亮度和克服灰度合并的新算法,即采用不同灰度区间分别均衡,并且采用设定最小灰度间隔和最大拉伸系数的均衡函数的方法,从一定程度上克服了上述缺点.     

语音增强用于坦克驾驶舱内无线语音通信

讨论了一种基于传统谱相减算法的改进方法。利用语音的短时平稳性,通过先验幅度比来连续更新噪声谱的估计,从而代替复杂的VAD(话音活性检测)。计算机仿真结果表明,这种改进方法有效抑制了噪声干扰,语音得到了增强,在极大地提高信噪比的同时,将残留的音乐噪声和语音失真保持在人耳听觉容忍的范围以内,从而较好的保持了语音自然度。     

采用FPGA通过BT.656接口实现传输4路视频流的方法

提出一种使用FPGA(现场可编程门阵列)实现一个ITU-R BT.656并行硬件接口传输4路CIF格式视频流的方法。该方法说明了从视频处理器到FPGA传输4路CIF格式视频流的数据结构,利用该数据结构,一个ITU-R BT.656的硬件接口可传输4路不同的CIF格式的视频数据流。FP-GA将4路视频数据流分离、插值生成D1(720×576像素)格式的数据输出给视频处理器。这种方法提高了视频处理器的扩展性,增加了视频处理器输出视频的路数。     

电爆炸箔断路开关的理论和实验研究

 采用金属箔电爆炸过程的二维数值计算模型，对含电爆炸金属箔断路开关的电感储能脉冲功率调节系统进行了数值计算。以此为基础，研制出了一种低电感型的电爆炸箔断路开关，并以4μF/75kV脉冲电容器组作为初级能源，13Ω电阻作为负载进行实验研究。研究结果表明：在负载上可获得约250kV，脉宽大于400ns的脉冲电压。