基模螺旋天线的研究

本文提出了一种计算基模螺旋天线的新方法.该方法采用螺旋线段对基模螺旋天线进行划分,只需少量分段就可用矩量法对其进行精确模拟分析.文中求出了螺旋天线上的电流分布和远场方向图,与直线段模拟计算结果吻合良好.求阻抗矩阵 Z时,利用螺旋天线的对称性和周期性,只需求出一小部分元素就可得到Z 矩阵的其它元素的值.该方法分段数少,使得计算时间和计算所需存储量大大减小,计算速度和精度显著提高.     

Toward better wireload models in the presence of obstacles

Wirelength estimation techniques typically contain a site density function that enumerates all possible path sites for each wirelength in an architecture and an occupation probability function that assigns a probability to each of these paths to be occupied by a wire. In this paper, we apply a generating polynomial technique to derive complete expressions for site density functions which take effects of layout region aspect ratio and the presence of obstacles into account. The effect of an obstacle is separated into two parts: the terminal redistribution effect and the blockage effect. The layout region aspect ratio and the obstacle area are observed to have a much larger effect on the wirelength distribution than the obstacle's aspect ratio and location. Accordingly, we suggest that these two parameters be included as indices of lookup tables in wireload models. Our results apply to a priori wirelength estimation schemes in chip planning tools to improve parasitic estimation accuracy and timing closure; this is particularly relevant for system-on-chip designs where IP blocks are combined with row-based layout     

整流二极管的IR对HTRB工作寿命的影响

整流器件在工作中的可靠性往往与其漏电流特别是在高温下的漏电流有密切关系,然而对高温下的漏电流往往关注不够。通过对常温与高温漏电流的对比测试,发现两者并没有一致的对应关系;通过对高温漏电流有较大差别的两组样品的高温反偏寿命试验表明:高温漏电流越大,高温反偏寿命越短,说明高温漏电流对高温反偏寿命有重要影响。依据此结果提出了通过对高温漏电流进行测试,实现对高温反偏寿命进行分档、筛选的设想。介绍了利用正向脉冲电流对二极管的pn结进行瞬态加热以实现对高温反向漏电流的快速测试的具体方法。     

手机电视发展现状及应关注的问题

介绍了全球手机市场发展现状和面向手持终端的数字电视广播网络标准化进展情况，分析了手机电视业务的市场发展前景，指出发展手机电视业务应关注的几个主要问题。     

Antiresonant reflecting optical waveguide-type vertical-cavity surface emitting lasers: comparison of full-vector finite-difference time-domain and 3-D bidirectional beam propagation methods

The cold-cavity modal characteristics of an antiresonant optical waveguide-type cylindrical vertical-cavity surface-emitting laser (VCSEL) are investigated through numerical simulations using a three-dimensional (3-D) bidirectional beam propagation method (BD-BPM) and a full-vector axisymmetric finite-difference time-domain (FDTD) method. Good agreement between the BPM- and FDTD-computed radial mode profiles as well as the mode-dependent radiation losses is obtained. The results of this paper establish the accuracy of the BD-BPM technique for simulating this class of devices and confirm effective-index method predictions that antiresonance conditions for cylindrical geometry devices (i.e., VCSELs) differ from those of planar geometry devices (i.e., edge emitters).     

LDAP在PKI应用中的缺陷研究

现今的LDAP轻量级目录访问协议,作为提供目录访问服务的协议,已成为支持PKI颁发证书和撤销证书列表的主流协议。本文讨论了LDAPv2和v3版本协议在PKI应用中存在的不足,并对LDAP在单机和多机目录服务的应用方面进行了分析,提出其缺陷和相对应的解决方案。     

HSDPA部署策略及覆盖、容量规划

本文介绍了HSDPA的发展背景,针对HSDPA的主要技术特点,依据市场发展规划、用户需求等方面对HSDPA部署进行探讨,并对HSDPA的覆盖与容量方面进行规划分析.     

基于逆浓度扩散及直方图的Mumford-Shah模型的MRA血管分割

直径的差别和造影剂的厚度不同造成血管在MRA成像中灰度不均匀,加上图像噪声的影响,使得血管的分割非常困难。而本文从血管在MRA图像中的特性出发,提出了逆浓度扩散模型,实现了血管的增强;另外本文还提出了基于直方图的Mumford-Shah模型计算方法,实现了图像的快速分割。实验表明,本文提出的方法能有效应用于二维及三维MRA图像中的血管分割。     

果蔬汁乳饮料的研制

对该饮料的配方、调合工艺的储存期进行试验，确定较为合适的工艺条件，针对沉淀分离现象，通过加入ＣＭＣ解决该问题。     

Inductor Current Sampled Feedback Control of Chaos in Current-Mode Boost Converter

A chaos control strategy for chaotic current-mode boost converter is presented by using inductor current sampled feedback control technique.The quantitative analysis of control mechanism is performed by establishing a discrete alterative map of the controlled system.The stability criterion,feedback gain,and corresponding critical duty ratio are obtained from the eigenvalue of the map.The simulation results verify the t heoretical analysis results of the control strategy.