焊膏工艺性要求及性能检测方法

焊膏是SMT工艺中不可缺少的钎焊材料,广泛应用于再流焊中;它是由一定的合金粉末和助焊剂均匀混合而成的膏状体。主要对SMT中焊膏的组成及焊膏性能检测方法进行了简要分析。     

基于形态学top-hat算子的多传感器图像融合

本文根据形态学top-hat算子能够提取图像中极大值与极小值区域的特点,将其应用于多传感器图像融合的两个重要领域——多聚焦图像融合和高分辨、多光谱图像融合.实验中将本文方法与Laplacian塔型变换、子波变换、主分量分析等方法进行了比较,结果表明本文所提的基于top-hat算子的融合方法具有优越的性能,拓广了top-hat算子的应用范围.     

A call admission and rate control scheme for multimedia support over IEEE 802.11 wireless LANs

Quality of service (QoS) support for multimedia services in the IEEE 802.11 wireless LAN is an important issue for such WLANs to become a viable wireless access to the Internet. In this paper, we endeavor to propose a practical scheme to achieve this goal without changing the channel access mechanism. To this end, a novel call admission and rate control (CARC) scheme is proposed. The key idea of this scheme is to regulate the arriving traffic of the WLAN such that the network can work at an optimal point. We first show that the channel busyness ratio is a good indicator of the network status in the sense that it is easy to obtain and can accurately and timely represent channel utilization. Then we propose two algorithms based on the channel busyness ratio. The call admission control algorithm is used to regulate the admission of real-time or streaming traffic and the rate control algorithm to control the transmission rate of best effort traffic. As a result, the real-time or streaming traffic is supported with statistical QoS guarantees and the best effort traffic can fully utilize the residual channel capacity left by the real-time and streaming traffic. In addition, the rate control algorithm itself provides a solution that could be used above the media access mechanism to approach the maximal theoretical channel utilization. A comprehensive simulation study in ns-2 has verified the performance of our proposed CARC scheme, showing that the original 802.11 DCF protocol can statically support strict QoS requirements, such as those required by voice over IP or streaming video, and at the same time, achieve a high channel utilization. Hongqiang Zhai received the B.E. and M.E. degrees in electrical engineering from Tsinghua University, Beijing, China, in July 1999 and January 2002 respectively. He worked as a research intern in Bell Labs Research China from June 2001 to December 2001, and in Microsoft Research Asia from January 2002 to July 2002. Currently he is pursuing the PhD degree in the Department of Electrical and Computer Engineering, University of Florida. He is a student member of IEEE. Xiang Chen received the B.E. and M.E. degrees in electrical engineering from Shanghai Jiao Tong University, Shanghai, China, in 1997 and 2000, respectively, and the Ph.D. degree in electrical and computer engineering from the University of Florida, Gainesville, in 2005. He is currently a Senior Research Engineer at Motorola Labs, Arlington Heights, IL. His research interests include resource management, medium access control, and quality of service (QoS) in wireless networks. He is a Member of Tau Beta Pi and a student member of IEEE. Yuguang Fang received a Ph.D degree in Systems and Control Engineering from Case Western Reserve University in January 1994, and a Ph.D degree in Electrical Engineering from Boston University in May 1997. From June 1997 to July 1998, he was a Visiting Assistant Professor in Department of Electrical Engineering at the University of Texas at Dallas. From July 1998 to May 2000, he was an Assistant Professor in the Department of Electrical and Computer Engineering at New Jersey Institute of Technology. In May 2000, he joined the Department of Electrical and Computer Engineering at University of Florida where he got the early promotion with tenure in August 2003 and has been an Associate Professor since then. He has published over one hundred (100) papers in refereed professional journals and conferences. He received the National Science Foundation Faculty Early Career Award in 2001 and the Office of Naval Research Young Investigator Award in 2002. He is currently serving as an Editor for many journals including IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing, and ACM Wireless Networks. He is also actively participating in conference organization such as the Program Vice-Chair for IEEE INFOCOM’2005, Program Co-Chair for the Global Internet and Next Generation Networks Symposium in IEEE Globecom’2004 and the Program Vice Chair for 2000 IEEE Wireless Communications and Networking Conference (WCNC’2000).     

胶性材料在混凝土坝裂缝处理中的应用

介绍了观音阁坝被埋水下6年越冬停浇面水平裂缝采用“粘贴T1密封胶及表面粘三元乙丙后锚固”的处理方案。结果表明,利用胶性材料处理运行中的重力坝迎水面裂缝,技术可靠,方法简单,经济合理。     

GSM-R无线网络设计方案探讨

本文就GSM-R无线网络设计中的几个方面进行了分析,包括设备的选型、频率配置、切换处理等.     

基于Agilent-VEE平台的测试系统设计与应用

美国安捷伦公司(原惠普公司)的Agilent-VEE，NI公司的Lab VIEW和Lab Windows／CVI开发软件等是国际上公认的优秀的虚拟仪器开发平台软件，人们对以应用后两者开发测试系统比较了解，但对VEE在测试系统中的应用少有介绍。本文介绍基于Agilent-VEE平台和GPIB总线的实用测试系统的组成、特点及仪器控制方式。     

基于JSP技术的Web网站安全性研究

通过对基于JSP技术的Web网站的体系结构的介绍．从Web服务器安全、JSP脚本编程及数据库安全等几方面分析研究了web网站存在的安全问题，并探讨了web网站开发时应采取的安全措施。     

测量光纤放大器小信号增益谱的一种简便方法

提出了一种用小功率宽带光源较精确测量光纤放大器小信号增益谱的方法。数值模拟表明 ,该方法是完全可行的 ,并且实验结果与数值模拟结果一致。该方法具有简便、易操作的特点。     

铝薄膜CMP影响因素分析

提出了在碱性抛光液中铝薄膜化学机械抛光的机理模型,对抛光液的pH值、磨料、氧化剂浓度对过程参数的影响做了一些试验分析。试验结果表面粗糙度的铝薄膜所需的最优化CMP过程参数:硅溶胶粒径为15～20nm,pH值为10.8～11.2,氧化剂浓度为2.5%～3%。     

下一代无线通信概念和技术

下一代无线通信(NextG:Next-generationwireless)的主流是随时随地的无线通信系统和无缝的高质量无线业务。概述了随时随地的无线通信和业务发展情况,并且介绍了为下一代无线通信的发展提供基础的关键技术。