基于协议栈芯片的嵌入式WEB服务器低成本实现方法

现在所存在的WEB服务器设计大多采用向微处理器上移植TCP／IP协议栈的方法，这些实现一般对微控制器的处理能力要求比较高，而且成本比较高，虽然数据传输速度较快，但在有些情况下这并不必要。本文介绍了一种利用集成了TCP／IP协议栈的接口芯片S7600以及MODEM模块接入Interact来构成WEB服务器的方式，这种方式对处理器性能要求不高，成本低，结构简单，性能稳定，在小规模的应用场合非常合适。     

WEB设计及网页制作中的几点考虑

Ｉｔｎｅｒｅｔ已经成为当今进行信息交流的重要手段，而其上一个站点信息资源的组织和制作是这个站点得以维持和发展的关键。在介绍了Ｉｎｔｅｒｎｅｔ基本概念的基础上，着重分析了ＷＥＢ上信息资源如何组织，总体风格如何定位，主页制作的一般原则问题，并就具体设计网页上应注意的问题进行了讨论。     

基于WEB的交互式统计分析系统设计

设计了一种基于WEB的交互式统计分析系统，科研人员可以通过其将费时费力的统计计算交给性能更强大的服务器去处理。从而发挥了服务器的计算能力，减轻了科研人员的计算负荷，提高了工作效率。     

网格阔步在后WWW时代

Oracle OpenWorld刚刚落下帷幕，从不曾平静的网格市场再次沸腾。Oracle发出的信号又一次聚焦了人们的目光，他向我们传递着这样一种声音，网格究竟会一举成为WEB服务的主流，还是沦落为昙花一现的科技垃圾，不仅仅取决于技术，更依赖于人的培育和引导。     

一把钥匙开一把锁 让你的无线更安全

泡一杯香浓的咖啡，倚在舒适的沙发上，捧着自己心爱的本本上网冲浪是一件多么惬意的事情。如果此时此刻，正有一名不知身份的“黑客”正“惬意”，而你却全然不知那该是件多么郁闷的事情。如果没有对你的无线网络及时加密，那么这种自己挣钱却便宜了别人的事情很有可能会发生在你身上，而且这还不算什么，如果“黑客”共享了你的网络，他们便可以轻松盗取你硬盘上的资料，这难道不是更郁闷的事情吗?其实，每个AP都具备一套完善的基站管理控制功能，通过一个简单的设置便可以为你的无线AP上一把锁，让你真正享受这份独有的快感。     

使用存储过程提高ASP的数据处理速度

在WEB应用系统中，WEB服务器在短时间内要响应大量请求，在这些请求中以查询、修改、更新数据库中的数据最为耗时，因此，查询、修改、更新数据库中数据通常成为整个WEB应用系统执行效率的瓶颈。存储过程是一组为了完成特定功能的SQL语句集，经编译后存储在数据库中，存储过程具有执行速度快、安全性高等优点。利用数据库管理系统处理数据快的特点，在ASP网页中调用存储过程提高系统的执行效率。     

WEB与数据库动态信息交换的CGI实现

探讨Ｗｒｂ服务与后台数据库信息的交换技术，给出客户既能浏览Ｗｅｂ服务器上的信息又能访问后台数据库的方法。该方法通过ＨＴＭＬ超文本标记语言的数据采集表ＦＯＲＭ接收用户的数据，并将这些数据提交给服务器，服务器再将其传递给ＣＧＩ程序，执行ＳＱＬ语句来实现对数据库的访问，并且在ＣＧＩ程序中将取回的记录转换成ＨＴＭＬ格式，再经服务器送给浏览器。     

数控教学系统研究现状与存在问题

本文分析了目前国内外数控教学系统研究概况以及目前国内数控技术及数控教学系统的现状，针对其不足提出了基于wEB的数控机床教学系统。     

一种新的通用报表模型的研究与实现

针对现有报表软件的不足，通过对报表数据结构的深入研究，提出了一种基于XML的报表模型，利用此模型开发出一套通过Web方式访问的通用报表系统。在该系统中，用户根据需求定义一个XML报表文件，系统即可动态加载并生成相应报表，使报表开发效率大大提升。     

CGI在Web开发中的应用

介绍ＣＧＩ的工作原理以及开发ＣＧＩ程序的一些基本方法，给出了ＰＥＲＬ语言编写的一用户验证程序以说明ＣＧＩ程序是如何工作的。     

Graphene‐Based Nanomaterials: Synthesis,Properties, and Optical and Optoelectronic Applications

Graphene, a two‐dimensional, single‐atom‐thick carbon crystal arranged in a honeycomb lattice, shows extraordinary electronic, mechanical, thermal, optical, and optoelectronic properties, and has great potential in next‐generation electronics, optics, and optoelectronics. Graphene and graphene‐based nanomaterials have witnessed a very fast development of both fundamental and practical aspects in optics and optoelectronics since 2008. In this Feature Article, the synthesis techniques and main electronic and optical properties of graphene‐based nanomaterials are introduced with a comprehensive view. Recent progress of graphene‐based nanomaterials in optical and optoelectronic applications is then reviewed, including transparent conductive electrodes, photodetectors and phototransistors, photovoltaics and light emitting devices, saturable absorbers for ultrafast lasers, and biological and photocatalytic applications. In the final section, perspectives are given and future challenges in optical and optoelectronic applications of graphene‐based nanomaterials are addressed.     

高速光纤综合通信网络平台研究

现代通信网络应能满足各种通信业务和通信容量日益发展的需求,实现话音、数据、视频、IP等业务的一体化综合交换和传输。在比较TDM、IP和ATM三种协议的基础上,提出"采用内置RPR和MPLS功能的MSTP平台"建设光纤综合通信网络平台的实现方法。MSTP采用SDH的数据帧结构,保持了SDH标准光接口、灵活分插低速信号、自愈环保护和功能强大的网管等优点,可对TDM、IP和ATM协议进行优化传输。     

Wireless IP and Its Challenges for the Heterogeneous Environment

The tremendous momentum toward building a mobile wireless Internet using the Internet Protocol (IP) has thrust many challenges upon the technology developers and the operators. These challenges encompass the 2.5G, 3G, and future solutions and standards. Some of the key issues deal with supporting IP traffic across different wireless and MAC protocols, end-to-end QoS and mobility, traffic engineering and scalability, protection/restoration, operations and management, authentication/privacy/security, billing, and content and context aware networking. This article addresses the drivers, the issues, and solutions (wherever possible) in the above areas, and concludes with a summarization of the challenges that lie ahead.     

卫星遥感温室气体的大气观测技术进展

全球、区域及城市的碳浓度、碳源汇信息是应对气候变化、达成双碳目标、完善国际谈判、支持治理政策制定与执行的重要依据。国际认可的“自上而下” 方法将卫星观测作为基础的通量计算技术, 是验证温室气体排放清单的重要手段。系统介绍了温室气体的卫星探测载荷原理、类别和发展, 以及反演、估算CO2、CH4 和N2O 的浓度和排放通量的方法, 还有探测缺失和误差存在的影响因素等; 分析了对卫星探测温室气体能力提高的迫切需求, 浓度反演和排放量估算精度不足, 以及N2O、氟化物等其他温室气体遥感研究缺乏、地基遥感验证能力薄弱等问题; 最后总结了我国温室气体卫星遥感技术的发展趋势, 主要是面向主被动高时空分辨率卫星的研制应用、高精度多尺度排放量估算(特别针对城市、小区域和点源尺度)、氟化物遥感评估等主题, 以加强对碳排放的量化观测, 并增强对碳循环的理解, 提高感知和应对气候变化的能力。     

卫星通信组呼业务MAC层研究

组呼通信在指挥调度中有着重要作用,而在一些地面没有基站的地方,就无法正常使用。卫星通信具有无视地形,通信范围广,不易受陆地灾害影响,易于建设等优点。把卫星通信和组呼通信结合在一起的卫星组呼通信技术兼顾两者的优点,能更好的发挥指挥调度这一作用。当前卫星组呼通信采用固定频率方式,组呼成员在一个频率下进行通信,这种方式实用性不好。本文研究的是移动卫星组呼,在GMR-1系统的基础上研究了卫星组呼通信中MAC层的功能,提出了MAC-Ready-Gcc、MAC-Dedicated-Gcc这两个为了支持组呼的状态,并针对在MAC层发生的PTT竞争提出了一种回退策略。     

机动6m抛物面天线车结构总体方案探讨

文章遵循策划、分解、综合及优化的总体方案研究思路,根据要求,提出了三个机动6 m抛物面天线车结构总体备选方案;针对系统结构组成,详细分析了天馈线、天线座、拖车以及系统标定等子系统所有可能的结构方案;最后综合权衡研究三个备选方案在技术、质量、成本、周期等多方面的优劣,选择了最佳结构总体方案,确保了所选方案具有合理性、可行性、经济性、先进性和科学性。实践证明,所选方案用户满意,实施效果良好。     

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.     

MATLAB在地理信息系统开发中的应用

GIS是计算机科学、地理学、测绘学、地图学等多门科学综合的技术,其核心是计算机科学,基本技术是数据库、地图可视化及空间分析。MATLAB是当前流行应用软件和编程语言,它集数学计算、可视化和编程于一体,易学易用。本文介绍了MATLAB软件的主要特点,阐述了MATLAB地图工具箱、数据库工具箱、用户图形界面及其与外部程序的接口等技术,并探讨了它们在地理信息系统开发中的应用。     

基于声卡的虚拟示波器设计

随着现代科学和信息技术的不断进步,示波器作为一种电子测量处理仪器也在不断发展并且已经变的越来越精密,也越来越智能.传统的模拟示波器受到低频响应能力和带宽限制等多方面因素影响在很多领域已显得力不从心,虚拟示波器的出现很好的解决了这些问题.本文以LabVIEW18版本为开发平台,设计制作了一款基于声卡的虚拟示波器.重点介绍...     

The effect of soldering process variables on the microstructure and mechanical properties of eutectic Sn-Ag/Cu solder joints

Fundamental understanding of the relationship among process, microstructure, and mechanical properties is essential to solder alloy design, soldering process development, and joint reliability prediction and optimization. This research focused on the process-structure-property relationship in eutectic Sn-Ag/Cu solder joints. As a Pb-free alternative, eutectic Sn-Ag solder offers enhanced mechanical properties, good wettability on Cu and Cu alloys, and the potential for a broader range of application compared to eutectic Sn-Pb solder. The relationship between soldering process parameters (soldering temperature, reflow time, and cooling rate) and joint microstructure was studied systemati-cally. Microhardness, tensile shear strength, and shear creep strength were measured and the relationship between the joint microstructures and mechani-cal properties was determined. Based on these results, low soldering tempera-tures, fast cooling rates, and short reflow times are suggested for producing joints with the best shear strength, ductility, and creep resistance.