高速公路通信系统建设探讨

随着国民经济和社会的发展，高速公路作为拉动经济发展的大动脉，已处于高速建设和发展的时期。截止到1999年底，全国高速公路已经超过10000公里。目前我国正在建设“五纵七横”高速公路网，计划到2000年，基本建成“两纵两横和三个重要路段”，全长17000公里，到2010年，基本建成“五纵七横”主干线，届时全国高速公路将达到36000公里。     

神州六号“背后”的IT系统

当神舟六号全面执行太空飞行的任务时，围绕着“神六”的七大系统（航天员系统、飞船应用系统、载人飞船系统、运载火箭系统、发射场系统、航天测控与通信系统、着陆场系统）。从天上的宇宙飞船，到地面的指挥控制，再到天地之间的通信和监测系统，IT就象一只无形的手，在把控和操作着一切。     

GLONASS应用中的问题及解决途径

利用对GLONASS长时间的监测数据，分析了现阶段GLONASS的定位现状，定位精度，可见星的分布状况和GLONASS的可用性。指出目前GLONASS定位中存在的可见星数目少，且分布不均，变化大等问题。提出：目前单独的GLONASS只能在某时段内提供有效的三维定位数据，加强与INS等其它导航设备组合是解决上述问题，促进GLONASS应用发展的有效途径。     

介绍一种新型通信系统—DCL无线电话系统

本文介绍了一种新的通信系统，该系统吸收了无中心拨号系统的优点，在自动中继、三次中继、有无线双向拨号通信及完善的监控记费系统方面有了重大的发展。使系统成为一种信价比高，适合于中国中小城市及农村的大容量、广域覆盖的通信系统。     

铱系统与AMPS系统之比较

文章介绍了移动通信工业发展的简短历史，并比较了铱系统与现有的先进移电话系统（ＡＭＰＳ）文章指出，尽管两个系统在结构业务，用户号码格式等方面大不相同，但在呼叫登记，呼叫建立，呼叫切换和小区复用方法上却惊人地相似，文章假设读者对现有的ＡＭＰＳ蜂窝系统已相当了解。     

非独立单元的3种系统可靠性的比较

研究了遵从二维指数分布的两单元的串联，并联和冷储备系统的可靠性，比较了它们的平均寿命和寿命方差。     

高空平台（HAPS）中继通信系统——一种新型无线通信系统

高空平台(HAPS：High Attitude Platform Station)系统利用距地面20km至50km的高空平台作为基站来提供电信业务和广播业务，它的出现是为了降低卫星通信系统和地面通信系统的昂贵花费，同时也考虑到了减小对人体的电磁辐射。理论上来说，和卫星通信系统相比，它具有高容量(1000倍bps／km^2)、高频谱利用率、时延小、易维护、易升级、可迅速建设等优点；     

陆基中远程防空系统

地面固定目标和机动目标对导弹和飞机威胁的有效防御需要采用多层防御。远距离雷达平台、干扰飞机和隐形炸弹的使用，以及放弃有人驾驶飞机的直接攻击而采用远距离、巡航和弹道导弹。突出了提高中远程拦截能力的必要性。     

罗罗卜镇有线电视系统工程设计方案

《浅谈使用国产设备保证电缆长距离传输》一文在《中国有线电视》1999年第 8期发表后 ,黑龙江、陕西、江苏、湖南等地读者来信询问罗罗卜网的设计情况。现撰此文供发表 ,以飨全国读者。     

GATV前端机房运行与维护若干问题的探讨

有线电视系统一般由前端系统、传输系统和分配系统三大部分组成。前端系统作为核心部分犹如人的心脏，其重要意义不言而喻，它的运行情况直接影响到整个CATV系统的稳定性和运行质量。对前端常见故障的熟悉和修复是每个机房工作人员应该所必有的基本功。     

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.     

企业VPN技术应用实施浅析

随着企业规模逐渐扩大,远程用户、分支机构、合作伙伴也在不断增多,关键业务的需求增加,出现了一种通过公共网络（如Internet）来建立自己的专用网络的技术,这种技术就是虚拟专用网（简称VPN）。本文首先介绍了VPN的概念,对VPN的实现技术进行了分类和适用性分析,然后分析了各种类型的企业在信息安全方面的需求和限制,根据不同企业的特点提出了不同的VPN解决方案,最后,对VPN在集成电路企业中的应用做了简单的拓朴展示。     

接入控制器安全网络管理系统的设计与实现

在讨论了接入控制器(AC)网络管理系统安全重要性的基础上,分析了SNMP协议的应用,包括对其3个版本SNMPv1、SNMPv2及SNMPv3的优缺点的对比,并解释了该设备网络管理系统采用SNMPv3版本的原因.详细介绍了AC所实现的管理信息库的内容,包括RFC1213协议、IEEE 802.1x协议、RMON协议、Web DHCP、EAP_OTP、EAP_MD5、EAP_TLS、EAP_SIM等多种认证协议以及网络管理系统的五大功能.最后阐述了AC安全网络管理系统结构的设计与实现.     

SOI Technologies Overview for Low-Power Low-Voltage Radio-Frequency Applications

Thanks to their structure, the SOI technologies present several intrinsic advantages for analog and RF applications. Indeed, as it is well established now, these technologies allow the reduction of the power consumption at a given operating frequency. Moreover, the high-insulating properties of SOI substrates, in particular when high resistivity substrate is used, make that these technologies are perfect candidates for mixed-signal applications. In the present paper, we will discuss the performances of the SOI technologies in radio-frequency range. First of all, the high-frequency behavior of SOI substrates, thanks to the characterization of transmission lines, will be shown. The impact of the SOI substrate resistivity on the performances of passive components will also be analyzed. Then, an overview of RF performances of SOI MOSFETs for two different architectures, fully- and partially-depleted, will be achieved and compared to the bulk ones. Finally, the influence of some specific parasitic effects, such as the kink effect, the self-heating effect and the kink-related excess noise, on the RF performances of SOI devices will be studied, thanks to a specific high-frequency characterization.     

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.     

雷达探鸟技术发展与应用综述

探鸟雷达已成为机场鸟击防范、风力发电场鸟击风险评估、鸟类自然保护区鸟情观测与科学研究的重要工具。文中首先论述了探鸟雷达的主要组成部分。然后,分析了地面杂波、空域杂波和其他无关目标对探鸟雷达探测效果的影响,进而介绍了传统的杂波抑制方法和相参雷达杂波抑制技术,以及先进的探鸟雷达采用的目标检测、目标跟踪、目标显示、数据记录和雷达组网等数据处理技术。接着,给出了当前的探鸟雷达能够获取的目标轨迹、回波大小、回波强度、信号波动、飞行速度、飞行高度等反映飞鸟目标特性的主要指标。最后,描述了国内外四种典型雷达探鸟系统,并针对雷达探鸟技术的未来发展提出了一些思考及可行性建议。     

CPLD在雷达发射机控制检测单元中的应用

随着雷达发射机技术的不断发展,越来越多的新技术应用于发射机设计中。复杂可编程逻辑器件CPLD和现场可编程门阵列FPGA,同以往的PAL和GAL器件相比,这些器件含有数量众多的可编程逻辑宏单元或逻辑块,规模大,组合能力强,设计成功能各异的逻辑电路,适合于时序、组合等逻辑电路。本文用CPLD对发射机控制功能进行综合处理,控制命令产生部分根据信号处理机通过串行链发来的控制命令产生控制命令,然后对发射机进行相应的控制,并对相关命令根据时序和故障情况进行逻辑链锁,达到最终控制发射机的目的。     

事件科普营销模式探究

从事件的视角看科普,已形成了社会公共事件、社会热点事件、社会突发事件等社会事件中嵌入科普的应急科普模式。但从科普的视角看事件,应急科普模式只是依托事件展开科普的组成部分,结合事件营销和科普营销的已有研究基础,本文提出事件科普营销模式,界定其依借公益性、聚焦性和危机性事件的内涵和依附性、新闻性、策划性三个特征,并从科学技术渗透疆常生活、资源整合、投入产出效率等角度论述其兴起的内在依据,并提出借势方式和造势方式下的四种路径。     

基于高斯分布的基站天线最佳方向角定位算法

为提高天馈问题被发现的准确性和维护效率,提出了基于高斯分布的最佳方向角解决方案来诊断运营商天馈覆盖问题。首先计算 UE 上报的具有定位信息的每个 MR 采样点与基站之间的位置方向信息,然后按照位置方向的一定角度间隔逐个统计各区间的MR采样点占比,取MR采样点占比最大的角度区间为该扇区的、基于用户热点分布的最佳天线方向角,最后将该最佳方向角与后台天线基础数据库中基站方向角进行比对,发现天馈系统接反、天线覆盖方向不合理、后台天线数据库错误等一系列天馈相关问题。经验证,采用该算法发现天馈问题的成本、准确率和效率较现有方法有明显改善?。     

关于物流机器人配送在社区疫情隔离中的应用探讨

机器人系统通常用于人工介入成本过高、危险过大或者效率过低的任务。近年来,随着人工智能、自动驾驶、物联网等众多相关学科的全面发展,机器人在很多行业的应用也越来越广泛、成熟;与民众生活密切相关的物流机器人的配送应用也在逐步发展;互联网下,电商的充分发展为物流机器人的配送应用提供了明确的应用场景。而在抗击新型冠状病毒肺炎疫情时期,区域人群需要实行严格隔离,隔断病毒人传人的感染途径。针对这样的状况,物流机器人可发挥其巨大优势,为民众提供物资配送服务,可有效隔断病毒人际传播,避免人员配送过程中可能带来的病毒扩散风险,针对性地解决疫情隔离阶段物资供给最后一里的难题。