广播电视传输覆盖技术体系的构建探讨

本文主要简单介绍了广播电视传输覆盖技术的三大系统,通过对现阶段广播电视传输覆盖技术的应用状况进行分析,来探讨构建广播电视传输覆盖技术体系的有效措施,研究广播电视传输覆盖技术的未来发展方向,以充分发挥广播电视传输覆盖技术,提高广播电视传输覆盖技术的应用效果,使其体系更加完善,扩大广播电视信号传输的覆盖面积,让更多地区的用户能够享受广播电视服务,推动广播电视行业的可持续发展,促进人们生活娱乐水平的提升。     

采用高增益塔康天线构建战术导航网

通过对塔康导航系统作用距离的估算,得出提高塔康导航系统作用距离的有效措施是提高塔康系统地面信标天线的增益,建议塔康地面信标采用高增益塔康天线构建战术导航网络。     

“电路分析”课程混合式教学探索与实践

本文以“电路分析”课程为例，借助云班课平台，采用“SPOC”与“BOPPPS”相结合的混合式教学模式，开展探究式、个性化、参与式教学。形成了“学生中心，产出导向，持续改进”闭环。经过近年来的不断改进，课程建设已初步完成。通过对三届学生的教学实践，发现采用“SPOC+BOPPPS”的线上线下混合式教学模式，学生学习积极性、主动性明显增强，同时学习效果也得到了显著提升。     

EPON在广电HFC网络双向改造建设中的应用

介绍了有线电视网络几种传统双向改造技术后,研究了如何将EPON这种基于以太网的无源光网络技术应用到有线电视HFC网络改造中,以最低的代价实现传统HFC网络的双向改造,同时指出了在应用中应该注意的几点问题,为当前及今后我国有线电视网络双向建设开辟了一条网络发展新路。     

基于Web的对话应用设计系统

信息技术领域的客服系统存在人力资源的运用效率低等问题,这给企业带来了大量的维护成本,对企业创新带来了一定的阻碍.因此本文提出一种新型的基于Web的对话应用设计系统,不仅提供了基于分支、循环、顺序等设计对话的基础流程控制单元,还包含大量垂直领域内的话题通用组件以辅助在短时间内设计出快速响应、容错率高的场景对话机器人,并提...     

Algorithm design for a class of base station location problems in sensor networks

Base station placement has significant impact on sensor network performance. Despite its significance, results on this problem remain limited, particularly theoretical results that can provide performance guarantee. This paper proposes a set of procedure to design (1− ε) approximation algorithms for base station placement problems under any desired small error bound ε > 0. It offers a general framework to transform infinite search space to a finite-element search space with performance guarantee. We apply this procedure to solve two practical problems. In the first problem where the objective is to maximize network lifetime, an approximation algorithm designed through this procedure offers 1/ε² complexity reduction when compared to a state-of-the-art algorithm. This represents the best known result to this problem. In the second problem, we apply the design procedure to address base station placement problem when the optimization objective is to maximize network capacity. Our (1− ε) approximation algorithm is the first theoretical result on this problem. Yi Shi received his B.S. degree from University of Science and Technology of China, Hefei, China, in 1998, a M.S. degree from Institute of Software, Chinese Academy of Science, Beijing, China, in 2001, and a second M.S. degree from Virginia Tech, Blacksburg, VA, in 2003, all in computer science. He is currently working toward his Ph.D. degree in electrical and computer engineering at Virginia Tech. While in undergraduate, he was a recipient of Meritorious Award in International Mathematical Contest in Modeling and 1997 and 1998, respectively. His current research focuses on algorithms and optimizations for wireless sensor networks, wireless ad hoc networks, UWB-based networks, and SDR-based networks. His work has appeared in journals and highly selective international conferences (ACM Mobicom, ACM Mobihoc, and IEEE Infocom). Y. Thomas Hou received the B.E. degree from the City College of New York in 1991, the M.S. degree from Columbia University in 1993, and the Ph.D. degree from Polytechnic University, Brooklyn, New York, in 1998, all in Electrical Engineering. Since Fall 2002, he has been an Assistant Professor at Virginia Tech, the Bradley Department of Electrical and Computer Engineering, Blacksburg, VA. His current research interests are radio resource (spectrum) management and networking for software-defined radio wireless networks, optimization and algorithm design for wireless ad hoc and sensor networks, and video communications over dynamic ad hoc networks. From 1997 to 2002, Dr. Hou was a Researcher at Fujitsu Laboratories of America, Sunnyvale, CA, where he worked on scalable architectures, protocols, and implementations for differentiated services Internet, service overlay networking, video streaming, and network bandwidth allocation policies and distributed flow control algorithms. Prof. Hou is a recipient of an Office of Naval Research (ONR) Young Investigator Award (2003) and a National Science Foundation (NSF) CAREER Award (2004). He is a Co-Chair of Technical Program Committee of the Second International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM 2007), Orlando, FL, August 1–3, 2007. He also was the Chair of the First IEEE Workshop on Networking Technologies for Software Defined Radio Networks, September 25, 2006, Reston, VA. Prof. Hou holds two U.S. patents and has three more pending. Alon Efrat earned his Bachelor in Applied Mathematics from the Technion (Israel’s Institute of Technology) in 1991, his Master in Computer Science from the Technion in 1993, and his Ph.D in Computer Science from Tel-Aviv University in 1998. During 1998–2000 he was a Post Doctorate Research Associate at the Computer Science Department of Stanford University, and at IBM Almaden Research Center. Since 2000, he is an assistant professor at the Computer Science Department of the University of Arizona. His main research areas are Computational Geometry, and its applications to sensor networks and medical imaging.     

有机/聚合物异质结电致发光器件的光电性能

器件结构是影响有机发光器件(OLED)性能的重要因素之一.采用8-hydroxyquinoline-aluminum(AlQ)作为发光层(EML)和电子传输层(ETL),polyvinylcarbazole (PVK)作为空穴传输层(HTL),制备了具有有机小分子/聚合物异质结结构的OLED器件,通过其电压-电流-发光亮度(V-J-B)特性测试,研究了HTL的引入及其膜厚对器件性能的影响.实验结果表明,HTL的引入有效地改善了OLED的光电性能,同时HTL膜厚对器件性能具有显著影响,当HTL膜厚为20 nm时,所制备的OLED器件具有最小的驱动电压和启亮电压、最大的发光亮度和发光效率.

Abstract：

The device construction plays an important role in improving the optoelectronic performance of organic electroluminescence devices (OLEDs). Heterojunction OLEDs with a configuration of glass/ITO/PVK/AlQ/Mg/Al were fabricated by using 8-hydroxyquinoline-aluminum (AlQ) as the emission layer (EML) and electron transport layer (ETL) and polyvinylcarbazole (PVK) as the hole transport layer (HTL). The effect of the HTL thickness on the performance of OLEDs was investigated with respect to the driving voltage, turn-on voltage, electroluminescence brightness and efficiency of the devices. Experimental results demonstrate that the optical and electrical properies of OLEDs are closely related to the HTL thickness. The device fabricated with the HTL thickness of 20 nm possesses the best photoelectric properties such as the minimum driving voltage and turn-on voltage, and the maximum electroluminescence brightness and efficiency.     

信息网络战新趋势研究

随着信息和网络技术的飞速发展,信息网络战的发展趋势及作战形式成为军事界热门话题.新时期的信息网络战已经成为一种优先被考虑的,贯穿战争整个过程的,破坏性极大的“顶级”作战形式,它的成败将直接关系到国家的安危与存亡.文章通过对最近几年信息网络战经典案例研究,总结分析了其所呈现出的新趋势,并为军队适应信息网络战的发展变化提出了几点建议.     

Enabling multiparty karaoke over Internet based on low‐level computers: practice and experiment

Karaoke is a system for amateur singing. The traditional online karaoke system does not allow multi‐singers to sing a song in one session. This study designs and implements multiparty karaoke over Internet (MKI) based on low‐level computers. The MKI is an online karaoke system of distributed architecture that allows multi‐singers to sing a song in one session. The MKI must deal with the problems of feedback, asynchronous audio latency at singers’ nodes, round‐trip latency at an inviter's node, and multi‐singers singing a song in one session. The acoustic isolation between microphone and speakers avoids feedback. Network Time Protocol avoids asynchronous audio latency. The third method's round‐trip latency in this study is within 86 ms, and all participants experience the simultaneous singing of the inviter and the invitees. MKI can be used for increasing leisure time, singing skills, and interpersonal relationships. Copyright © 2011 John Wiley & Sons, Ltd.     

数据中心用列间空调的优化布局方案研究

为研究列间空调在机柜列内的合理位置布局以提高冷量利用率,本文对某工程实例基于实地查勘数据采用专业的CFD模拟软件建立起仿真模型进行了数值模拟研究,分析当前建设方案的可优化之处,进而研究了两种调整方案并与原方案展开了横向对比.综合3种建设方案的结果得出优化方案以对相关类似建设工程提供有益参考.