关键词： service discovery   Jini   multi-agent system   Intelligent agents   Jini   Ethers  

摘要： The emergence of ad-hoc pervasive connectivity for devices based on Bluetooth-like systems provides a new way to create applications for mobile systems. We seek to realize ubiquitous computing systems based on the cooperation of autonomous, dynamic and adaptive components (hardware as well as software) which are located in vicinity of one another. In this paper we present this vision. We also describe a prototype system we have developed that implements parts of this vision – in particular a system that combines agent oriented and service oriented approaches and provides dynamic service discovery. We point out why existing systems such as Jini are not suited for this task, and how our system improves on them.

关键词： NMR   chemical shift calculation   DNA   nucleic acids   kissing complex  

摘要： The large majority of analytical NMR methods in chemistry or biochemistry are based on the quality of the chemical shift dispersion. The purpose of this work is to show that theoretical chemical shift back calculation starting from structures can be used to select molecular modeling structures in order to differentiate several conformational possibilities. Here we report the result of the chemical shift calculation carried out on two original structures corresponding to two DNA 'kissing complexes'. The 46 nucleotides sequence corresponds to the RNA deoxyribose analogous implied in the HIV-1(Lai) dimerization process. It is interesting to note that, even in cases we are very far from the classical helical structure (loop-loop interaction, AA base pairing, base stacking, misappariement...), the theoretical chemical shift is in very good agreement with the experimental chemical shift (+/-0.25 ppm). The satisfactory results obtained enable us to conclude that the comparison of the proton chemical shifts is an invaluable tool making it possible to select or to validate oligonucleotides structures. (C) 2001 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.

关键词： 移动IP   多播   移动计算   Interent   路由器   代理   计算机网络  

摘要： 分析了移动ＩＰ和多播实现的原理，在此基础上，讨论了使移动ＩＰ支持多播的方案，包括多播组管理和报文路由的实现，并对它们进行了分析比较。

关键词： 宽带互联网   分布式计算   地理信息系统   移动计算   RTOS   微型嵌入式操作系统   微型嵌入式GIS  

摘要： 近年来 ,嵌入式应用技术蓬勃发展 ,市场迅猛扩大 ,产品已经深入到工业生产和人们生活的各个角落 .制造工业、过程控制、通讯、汽车、船舶、航空、航天、军事装备、消费类产品等都已成为嵌入式计算机的应用领域 ,给微型嵌入式 GIS软件的研究与发展提供了良好的机遇 .本文从技术发展背景、含义及特点、应用发展前景、国内外发展动态、我国微型嵌入式 GIS软件平台发展的重要意义以及发展微型嵌入式 GIS软件平台的技术探讨与建议等几方面对微型嵌入式 GIS软件平台进行了详细的论述 .

关键词： 计算机通信网   体系结构   移动通信  

摘要： 移动计算机通信网络是用户计算机可以在网内随意移动的计算机通信网络,因此,用户计算机是便携的,如笔记本电脑、手持机、PDA和Wearable Computer(可穿戴计算机)等,并装有无线通信设备.使用时就像移动电话一样,用户可以在无线网络覆盖的任何地方随意发送和接收各种数据信息.用户可以在室内或室外,可以处于静止或运动状态,而且可以在不同的地区,甚至不同的国家之间进行漫游.移动计算机通信网络与计算机网络一样可以是局域网,也可以是广域网.

关键词： 分布式计算机系统   分布系统   可靠性评估   检测与诊断   分布式信息系统   会议录   移动计算   容错技术   实时系统   无线网络  

摘要： Y2001-62790 01158272000年 IEEE 可靠性分布系统会议录=2000 IEEEsymposium on reliable distributed systems[会,英]/IEEEComputer Society Technical Committee on DistributedComputing.—IEEE,2000.—263P.(EC)本会议录收集了于2000年10月16～18日在德国 Nurnberg 召开的可靠分布系统会议上发表的26篇论文,内容涉及无线网络与移动计算,可靠性规约,检测与诊断,实时系统,容错与复现,数据库与数据访问,可靠性评估,分布式信息系统中的集成容错技术与安全性。

关键词： 移动Agent   移动计算   标准   人工智能   通信网  

摘要： 移动Agent计算模式是传统计算模式的拓展,它集中了移动计算和Agent的优势,为分布计算提供了新的发展。为了促进移动Agent技术的发展,OMG和FIPA相继推出了相关标准。本文将对移动Agent技术标准进行剖析,并介绍第一个符合标准的移动Agent平台——Grasshopper。

关键词： 回国创业   留学生归国   嵌入式系统   留学工作   核心软件   人性化管理   留住人才   美国邮政总局   移动计算   管理运作模式  

摘要： 同前几年的出国热相反,近年来中国又掀起了一股留学生归国创业热。究竟是什么原因使当年的游子纷纷回家?记者为此采访了曾在美国留学工作了六年,回国创业已两年的移软科技(南京)有限公司总裁王继平先生。

关键词： 移动计算   计算机网络   移动通信  

关键词： prewrite   mobile transaction   pre-commit   data availability  

摘要： We incorporate a prewrite operation before a write operation in a mobile transaction to improve data availability. A prewrite operation does not update the state of a data object but only makes visible the future value that the data object will have after the final commit of the transaction. Once a transaction reads all the values and declares all the prewrites, it can pre-commit at mobile host (MH) (computer connected to unreliable mobile communication network). The remaining transaction's execution (writes on database) is shifted to the mobile service station (MSS) (computer connected to thr reliable fixed network). Writes on database consume time and resources and are therefore shifted to MSS and delayed. This reduces wireless network traffic congestion. Since the responsibility of expensive parr of the transaction's execution is shifted to the MSS, it also reduces the computing expenses at mobile host. A pre-committed transaction's prewrite values are made visible both at mobile and at fixed database servers before the final commit of the transaction. Thus, it increases data availability during frequent disconnection common in mobile computing. Since a pre-committed transaction does not abort, no undo recovery needs to be performed in our model. A mobile host needs to cache only prewrite values of the data objects which take less memory, transmission time, energy and can be transmitted over low bandwidth. We have analysed various possible schedules of running transactions concurrently both at mobile and fixed database servers. We have discussed the concurrency control algorithm for our transaction model and proved that the concurrent execution of our transaction processing model produces only serializable schedules. Our performance study shows that our model increases throughput and decreases transaction-abort-ratio in comparison to other lock based schemes. We have briefly discussed the recovery issues and implementation of our model.