苯和甲苯差分吸收光谱方法的实验室测量研究

本文介绍了差分光学吸收光谱法(DOAS)测量大气污染气体浓度的基本原理。DOAS方法就是利用氙灯发出的紫外—可见光，经望远镜准直后再经过一段距离的传输，由望远镜来接收．在传输中，由于各种不同的分子在不同的波段对光有不同的吸收特征，使光谱具有了污染物的特征，再通过与光源发出的光进行比较，反演这些气体在大气中浓度．我们将DOAS方法应用在监测有机物上，在分析光谱的过程中，应用多项式拟合和最小二乘法，从而精确地从测量光谱中来反演出大气中污染气体的浓度．文中用DOAS方法测量了苯和甲苯的样品，并分析了结果，结果和理论吻合．可为环境中有机污染物监测提供可靠的方法。     

Joint coding-precoding with low-complexity turbo-decoding

We combine error-control coding with linear precoding (LP) for flat-fading channels, as well as for wireless orthogonal frequency-division multiplexing transmissions through frequency-selective fading channels. The performance is analyzed and compared with the corresponding error-control-coded system without precoding. By wedding LP with conventional error-control coding, the diversity order becomes equal to the error-control code's minimum Hamming distance times the precoder size. We also derive a low-complexity turbo-decoding algorithm for joint coded-precoded transmissions. We analyze the decoding complexity and compare it with an error-control-coded system without LP. Extensive simulations with convolutional and turbo codes for HiperLan/2 channels support the analysis and demonstrate superior performance of the proposed system.     

基于TMS320C6x实现多载波QPSK信号全数字化整体解调

提出并证明了一种群路FDMA/QPSK(频分多址/正交相移键控)信号全数字化整体解调的新方法,该方法根据信道构成特点和信号调制方式,将直接分路法和常规多相FFT(快速傅里叶变换)分离法相结合,构成了一种简化的等效多相FFT分路方法,再将输出的数字信号送到数字式解调器,实现了多载波信号的全数字化整体解调,其特点是软件和硬件结构简单、系统计算量小,且易于DSP实时实现,现已用该算法进行了32路FDMA/QPSK信号整体解调的计算机仿真实验,结果表明该方法是可行的.     

虚拟仪器在教学中的应用

主要介绍了Multisim2001中虚拟仪器库中函数发生器、示波器的使用方法及功能；并在Multisim2001环境中仿真单管放大电路、桥式整流滤波电路。由调试结果，分析了其在教学中应用的可行性。     

YAG：Nd激光照射犬气管粘膜的实验研究

An experimental study for the pathologic changes of the canine tracheal mucosa under YAG:Nd laser ablation was performed in order to master the appropriate parameters for the clinical treatment of YAG:Nd laser. 6 male and female Mongolia dogs weighing 13-18 kg were received 20W YAG:Nd laser treatment and their pathologic changes were examined instantly and 3, 7, 14 and 28 days after ablation.     

固定波形时间保护间隔OFDM系统循环卷积特性研究

针对固定波形时间保护间隔OFDM系统接收端OFDM信息符号和信道冲击响应之间不具有循环卷积特性的系统特点,本文提出一种简单有效的信号处理算法对该系统接收端OFDM信息符号和信道冲击响应之间的循环卷积特性进行恢复。理论分析和计算机仿真表明,该算法能够恢复接收端此循环卷积特性;在时延扩展和AWGN信道条件下,系统误符号性能受到的影响微弱。     

CDMA位置服务系统的本地定位平台建设

移动位置业务是移动通信网络的一项特色增值业务．将成为今后几年的业务增长亮点之一。中国联通总部的增值业务部于2002年采用集中设置方案，进行了CDMA位置服务系统一期工程的建设。本地定位平台建立于中国联通CDMA位置服务系统基础之上．其功能由以下的一项或多项组合而成：门户功能、中间件功能、GIS系统的的功能和对本地的CP进行管理和计费的功能。     

Effect of Stress State on Growth of Interfacial Intermetallic Compounds Between Sn-Ag-Cu Solder and Cu Substrates Coated with Electroless Ni Immersion Au

Excessive intermetallic compound (IMC) growth in solder joints will significantly decrease the reliability of the joints. IMC growth is known to be influenced by numerous factors during the component fabrication process and in service. It is reported that, other than temperature and holding time, stress can also influence the IMC growth behavior. However, no existing method can be used to study the effect of stress state on IMC growth in a controlled manner. This paper presents a novel method to study the effect of stress on interfacial IMC growth between Sn-Ag-Cu solder and a Cu substrate coated with electroless Ni immersion Au (ENIG). A C-ring was used and in-plane bending induced tensile and compressive stresses were applied by tightening the C-ring. Results revealed that in-plane compressive stress led to faster IMC growth as compared with in-plane tensile stress.     

OMA协议下的TS节目DRM解决方案

数字版权保护技术已经成为网络电视中除了视频编码技术以外的又一项核心技术。它用于保护内容所有人的版权,控制客户对于内容的使用。文章在阐述OMADRM标准的基础上,提出了一种适应国内广电系统实际播控环境的TS制式节目的DRM解决方案,并根据自行开发的演示系统,就其加密效率加以论证。