GaSb衬底上InAsxSb1-x合金的低压MOCVD生长和表征

采用自制的低压金属有机化学气相淀积设备,用三甲基镓、三甲基铟作为Ⅲ族源,三甲基锑和砷烷作为Ⅴ族源在(100)面GaSb和GaAs单晶衬底上分别外延生长了InAsSb材料.用X射线双晶衍射、原子力显微镜、扫描电镜和电子探针能谱仪等对材料特性进行了表征,研究了生长温度、Ⅴ/Ⅲ比、过渡层等生长参数对外延层质量的影响.获得了与GaSb衬底晶格失配度为0.4%的表面光亮且晶体质量较好的InAs0.85Sb0.15外延层.     

光学期刊联合编辑部成功参展中国国际光电周

第十一届ILOPE展会于2006年12月5-7日在北京召开,此次展会包含了一个光电展览,四个技术/产业论坛和一个中外贸易交流会.吸引了来自14个国家近400家参展商,展出面积达1万多平米.国内主流的激光、光学和红外厂商悉数到场,同时国外FLIR、光谱物理、相干、镭宝、贰陆、HGH、Senko、美国Photonics、尼康等国际知名企业也携新产品、新技术参与.     

Graph Laplacian Matrix Learning from Smooth Time-Vertex Signal

In this paper,we focus on inferring graph Laplacian matrix from the spatiotemporal signal which is defined as“time-vertex signal”.To realize this,we first represent the signals on a joint graph which is the Cartesian product graph of the time-and vertex-graphs.By assuming the signals follow a Gaussian prior distribution on the joint graph,a meaningful representation that promotes the smoothness property of the joint graph signal is derived.Furthermore,by decoupling the joint graph,the graph learning framework is formulated as a joint optimization problem which includes signal denoising,timeand vertex-graphs learning together.Specifically,two algorithms are proposed to solve the optimization problem,where the discrete second-order difference operator with reversed sign(DSODO)in the time domain is used as the time-graph Laplacian operator to recover the signal and infer a vertex-graph in the first algorithm,and the time-graph,as well as the vertex-graph,is estimated by the other algorithm.Experiments on both synthetic and real-world datasets demonstrate that the proposed algorithms can effectively infer meaningful time-and vertex-graphs from noisy and incomplete data.     

产品线落后是外资平板战略衰退的核心表现

"本土厂商的败退,导致外资品牌平板电视在国内市场的整体销售额比重增至59%,外资品牌再次超越国产品牌"<涨或降?国产平板价格走向两难>,"商业",2007年8月20日).现在看来,贵刊这篇文章借用的德国人提供的数据,并未对国产品牌彩电提供商的现状故到准确了解.而笔者在参观了今年高交会的家电展厅后,更加认识到外资品牌已被国内同行甩在了身后.     

8848从顶峰走向衰微的历史见证

人不可能两次迈进同一条河流，而8848却似乎可以。近段时间，因为速达的“收购传闻”，8848再一次成为业界关注的焦点。因为如今的8848内部风雨飘摇，外部官司缠身，它有何被收购的价值?公司总裁吕春维为何早早投怀送抱、急于为收购造势?谁是这一出“收购闹剧”的幕后主使?在诸多疑问背后，很少有人能看清事情本质。老8848的创始人王峻涛知道，但他不说，因为此8848已非当年之彼8848。几年前，盛极一时的老8848就是这样被幕后资本强行拉入分拆和兼并的资本游戏，被胜利冲昏头脑的大股东妄图运用资本力量主导企业发展，对他们来说，更重要的是上市圈钱。但因为牵扯的利益太多，诱惑太多，8848的发展最终陷入极度迷茫中，在资本疯狂追逐最大利益的时候，企业却错过了发展的最佳时机，并从此一步步走向衰微。6年来，8848经历了最辉煌的巅峰时期，同样也经历了无数是是非非。即使当时剩下的钱仍可使8848运营数十年，但是，商人们已经对8848的未来失去了耐心与信心，老8848最终难逃遭清算厄运。后来，所谓“王者归来”的新8848更是虚有其表，连核心业务也惹上纠纷，最后股东终于按捺不住……现在经常有人问王峻涛，如果当时不要上市，如果当时不分拆，如果……但王说：假设没有意义，我懂得了一点：创业者要坚持、坚持、再坚持。张朝阳也说：做自己的，不要听华尔街的。或许这就是本文要寻找的答案。     

中国这样进行专利谈判肯定不行——美国移通半径公司亚太区总裁雷鸣硅谷对话《IT时代周刊》

3G谈判受阻的主要原因是在谈判中，电信研究院作为一家研究机构实力太弱，如果能聘请外国在专利谈判上有丰富经验的律师或律师行主谈，加上中国政府的免费授权政策和运营商有关采购3G设备政策的出台，专利谈判可能是另外一个结果。     

收视价值的迷失 高端人群在远离卫视 2008目睹中国电视之怪现状

近两个月来,本刊网站的论坛里又不太安静。有个叫"高清迷"的香港网友遭到了广东一些网友的质疑。彼此论战的焦点大部分在说香港电视好看或不好看。"高清迷"网友说大陆电视越来越好,水平已经超过香港的电视节目。广东网友们则是缅怀香港电视的辉煌历史。这原本是简单的我说你好你说我好,互相捧场的事情,但是网络的奇妙性在于事情并没有朝积极的方向发展,其结果是吵架不可避免的发生了。外来的和尚是不是会念经,我们先不去管他。重要的是我们要弄清楚自己是怎么回事。本文,是专业电视人对我国各省卫视台做的调查评估。让我们了解一下我国的电视台的现状吧。     

上海慕尼黑电子展暨同期展会见闻

2007年3月21日～23日的上海新国际博览中心是格外的热闹,超过2万名来自电子行业的专业观众汇聚与此.吸引他们来到这里的原因就是慕尼黑上海电子展,慕尼黑上海激光、光电展(LASER. World of Photonics China)、中国国际半导体设备、材料、生产和服务展览暨研讨会(SEMICON China),以及中国国际电子电路展览会(CPCA Show)四大电子业权威品牌展联合在此举行.     

ADSL服务

现在使用ADSL上宽带网的用户是越来越多了,对ADSL设备的维护也成了一个不容忽视的问题.只有维护保养好它,不但让你的"宽带之旅"省心又省力,还能延长其寿命.ADSL的维护可分为软件和硬件两个方面来分析,软件主要是PPPOE协议的问题,和计算机本身的气操作系统,和网卡方面的事情.硬件主要是局端的节点设备,和用户端猫的问题.还有通信的线路等一些因素.     

Intelligent Passive Detection of Aerial Target in Space-Air-Ground Integrated Networks

Passive detection of moving target is an important part of intelligent surveillance. Satellite has the potential to play a key role in many applications of space-air-ground integrated networks(SAGIN). In this paper, we propose a novel intelligent passive detection method for aerial target based on reservoir computing networks. Specifically, delayed feedback networks are utilized to refine the direct signals from the satellite in the reference channels. In addition, the satellite direct wave interference in the monitoring channels adopts adaptive interference suppression using the minimum mean square error filter. Furthermore, we employ decoupling echo state networks to predict the clutter interference in the monitoring channels and construct the detection statistics accordingly. Finally, a multilayer perceptron is adopted to detect the echo signal after interference suppression. Extensive simulations is conducted to evaluate the performance of our proposed method. Results show that the detection probability is almost 100% when the signal-to-interference ratio of echo signal is-36 dB, which demonstrates that our proposed method achieves efficient passive detection for aerial targets in typical SAGIN scenarios.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

电磁兼容检测实验室测试系统相符性比对研究

电磁兼容测试结果与检测实验室可靠性程度直接相关,检测实验室自身质量是保证电磁兼容测试结果准确性先决条件,检测实验室测试系统相符性则成为电磁兼容系统性能评估中需要考虑的关键内容和重要指标。因此,检测实验室测试系统相符性比对是实现电磁兼容系统评估研究的基础工作之一。本文首先针对电磁兼容检测实验室测试系统相符性比对的特点,结合自己几年来的测试实践论述了电磁兼容检测实验室测试系统相符性对比方案,然后提出了具体的案例同时进行了详细的分析,最后总结出了影响电磁兼容检测实验室测试系统相符性因素,整个案例和分析过程及结果可作为电磁兼容检测实验室测试系统相符性比对的手段和依据,具有重要的现实指导意义。     

圆球微腔对水蒸汽的敏感特性仿真实验研究

研究了圆球微腔在水蒸汽传感中应用的可行性。通过测试在有/无水蒸汽的气室环境下,圆球微腔透射光谱的变化来对气室水蒸汽浓度情况进行传感测试。仿真实验结果显示:在有无水蒸汽干扰的条件下系统输出光强有明显的变化,即研制基于圆球微腔的传感器是可行的。     

量化秩非参数CFAR检测器在杂波边缘中的性能分析

人们常用均匀背景、多目标和杂波边缘3种典型背景来衡量雷达目标检测器的性能,但在现有文献中缺乏量化秩（Rank Quantization,RQ）非参数检测器在杂波边缘中虚警概率的理论模型,缺乏RQ非参数检测器与经典的参量型检测器在杂波边缘中虚警控制能力的比较.本文给出了RQ检测器在杂波边缘中虚警概率的解析表达式,并比较了它与非相干积累CA （Cell Averaging）,GO （Greatest Of）,OS （Ordered Statistic）恒虚警方法在杂波边缘中的虚警控制能力.可以看出,采用高秩量化门限的RQ检测器的虚警控制能力要优于低秩量化门限的情况,在瑞利分布杂波边缘情况下,RQ检测器的虚警控制能力与非相干积累OS方法接近.但是当强杂波变为长拖尾分布的非高斯杂波时,非相干积累CA,GO和OS参量型检测方法的虚警概率产生了3个数量级以上的上升,且不能降回到原始设定的虚警概率.而RQ检测器显示出了非参量检测器的优势,即当杂波背景的分布类型发生变化后,它仍然可以保持虚警概率的恒定.     

一种改善LED背光亮度均匀性的新型反射膜研究

在LCD的LED背光腔体的底面设计了新型曲面形状及性能的反光膜,将扩散膜反射回灯腔底部的光重新反射回出光口以改善亮度均匀性能;在侧面设计了镜面反射膜,将位于LED矩阵边缘区域由LED射向灯腔侧壁的光反射重新射向出光口,增加了LED背光边缘区域的亮度,从而改善了背光边缘区域较暗的亮度不均匀状况.根据此类反射膜的设计完成了反射膜的制备,并应用于38 cm LED背光源样品.测试结果显示,设置反射膜的LED背光的亮度均匀性值为10.2%,明显优于未设置反射膜的值16.8%,亮度提高了29%左右,表明该种新型反射膜可以提高亮度并改善亮度均匀性.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

红外热像在石化设备检测中的应用

本文在概述红外热象技术应用于石化设备检测的基本原理和方法的同时，着重介绍了对石化重点装置催化再生器的检测及其衬时故障诊断，以及热管道、阀门外保温效果评估等方面的应用情况。并对此项技术在石化企业的应用前景和研究方向做了一定的介绍。     

DMSS-动态Merkle可信树签名方案

 本文通过构造子树及密钥的动态循环更新实现了二叉树的动态更新,改进了Merkle可信树签名方案中,签名数量的增加使得二叉树庞大导致签名效率低下的缺陷,使签名的数量不在受到二叉树大小的影响.此外,本文对改进后的方案进行了安全分析,分析结果表明,该签名方案具有原始Merkle可信树签名方案的安全性,并且,由于采用了分时间段的密钥管理方式,该方案还具有前向安全性.     

Alternative Schemes for Dynamic Secure VPN Deployment in UMTS

Three alternative schemes for secure Virtual Private Network (VPN) deployment over the Universal Mobile Telecommunication System (UMTS) are proposed and analyzed. The proposed schemes enable a mobile node to voluntarily establish an IPsec-based secure channel to a private network. The alternative schemes differ in the location where the IPsec functionality is placed within the UMTS network architecture (mobile node, access network, and UMTS network border), depending on the employed security model, and whether data in transit are ever in clear-text, or available to be tapped by outsiders. The provided levels of privacy in the deployed VPN schemes, as well as the employed authentication models are examined. An analysis in terms of cost, complexity, and performance overhead that each method imposes to the underlying network architecture, as well as to the mobile devices is presented. The level of system reliability and scalability in granting security services is presented. The VPN management, usability, and trusted relations, as well as their behavior when a mobile user moves are analyzed. The use of special applications that require access to encapsulated data traffic is explored. Finally, an overall comparison of the proposed schemes from the security and operation point of view summarizes their relative performance. Christos Xenakis received his B.Sc. degree in computer science in 1993 and his M.Sc. degree in telecommunication and computer networks in 1996, both from the Department of Informatics and Telecommunications, University of Athens, Greece. In 2004 he received his Ph.D. from the University of Athens (Department of Informatics and Telecommunications). From 1998–2000 was with the Greek telecoms system development firm Teletel S.A., where was involved in the design and development of advanced telecommunications subsystems for ISDN, ATM, GSM, and GPRS. Since 1996 he has been a member of the Communication Networks Laboratory of the University of Athens. He has participated in numerous projects realized in the context of EU Programs (ACTS, ESPRIT, IST). His research interests are in the field of mobile/wireless networks, security and distributed network management. He is the author of over 15 papers in the above areas. Lazaros Merakos received the Diploma in electrical and mechanical engineering from the National Technical University of Athens, Greece, in 1978, and the M.S. and Ph.D. degrees in electrical engineering from the State University of New York, Buffalo, in 1981 and 1984, respectively. From 1983 to 1986, he was on the faculty of Electrical Engineering and Computer Science at the University of Connecticut, Storrs. From 1986 to 1994 he was on the faculty of the Electrical and Computer Engineering Department at Northeastern University, Boston, MA. During the period 1993–1994 he served as Director of the Communications and Digital Processing Research Center at Northeastern University. During the summers of 1990 and 1991, he was a Visiting Scientist at the IBM T. J. Watson Research Center, Yorktown Heights, NY. In 1994, he joined the faculty of the University of Athens, Athens, Greece, where he is presently a Professor in the Department of Informatics and Telecommunications, and Director of the Communication Networks Laboratory (UoA-CNL) and the Networks Operations and Management Center. His research interests are in the design and performance analysis of broadband networks, and wireless/mobile communication systems and services. He has authored more than 150 papers in the above areas. Since 1995, he is leading the research activities of UoA-CNL in the area of mobile communications, in the framework of the Advanced Communication Technologies & Services (ACTS) and Information Society Technologies (IST) programmes funded by the European Union (projects RAINBOW, Magic WAND, WINE, MOBIVAS, POLOS, ANWIRE). He is chairman of the board of the Greek Universities Network, the Greek Schools Network, and member of the board of the Greek Research Network. In 1994, he received the Guanella Award for the Best Paper presented at the International Zurich Seminar on Mobile Communications.     

自动测试系统中的总线技术

自动测试系统满足现代科研生产中对测试高速度和高精度的要求,其发展方向是标准化、模块化和系列化,而标准的总线技术是满足这三化的关键技术,总线技术作为自动测试系统的核心,其发展推动了自动测试系统的更新换代.按照自动测试系统中出现的总线技术的顺序,依次对GPIB,VXI,PXI,LXI的基本特性、优缺点及应用进行概括,重点是结合在实际中组建自动测试系统对总线的选型,从宏观上比较了选取传统的卡式仪器总线或基于以太网的新型总线的因素.从而使用户在选取总线时更有针对性和目的性.