关键词： 名字   可移动即插即用网络   计算机网络   移动计算  

摘要： 计算机网络给用户带来了很大的方便 .但是 ,在目前仍然存在着配置复杂 ,不能够有效满足用户移动计算的需求等问题 ;虽然 IPv6为解决上述问题提供了一定的机制 ,但是仍然存在一些问题 .本文在 IPv6基础上结合 DNS和移动计算技术 ,提出了一种基于名字的可移动即插即用网络技术 ,并就其中可能出现的三种安全性问题提出了相应的解决方案 .它具有主机的即插即用、可移动性和更安全等特点 .

关键词： 中间件   面向对象   移动计算   计算机   软件  

摘要： 一、应用背景 伴随功能更强的计算机的产生,银行内部许多新的需求相继出现;移动计算也给传统的以主机为中心的计算模式带来了新的挑战,业务人员经常需要在不太安全的公共网上传送银行内部信息.在银行业务延伸服务的过程中,需要将结算系统的数据与客户数据进行组合才能提供新的服务,从而需要新的办法来把分布在不同环境中的大量应用有效集成起来.这些需求要与银行原有的信息系统实现无缝的连接.

关键词： 个人电脑   发展历史   计算能力   手提式计算机   移动计算   微型化  

摘要： 个人电脑在一刻不停地更新换代,处理器运算速度越来越快,数据存储容量越来越大、操作系统功能越来越强、应用程序也越来越丰富。但这些进步都属于计算能力的范畴。

关键词： 无线移动Ad hoc网络   自组网   网络连通性   网络性能分析   多跳网络   移动计算   移动通信   Ad hoc技术   节点连接  

摘要： 论文首先对当前Ad hoc的研究现状进行了归纳总结,提出了\"Ad hoc技术\"的一般性概念;随后给出节点连接概率的一般性理论推导,以节点连接概率为基础,依据随机图论的数学工具,探讨了区域形状参数、节点覆盖范围、节点移动性等因素对网络连通性的影响,以及网络连通性与相邻节点个数、路径长度等因素的关系,得出了保持网络全连通时对不同参数的要求的一般性结论.最后,论文通过计算机仿真对以上的理论分析进行了验证,并在此基础上给出了Ad hoc网络实验系统的仿真结果.

关键词： 嵌入式移动数据库管理系统   移动计算   事务   双向复制   XML  

摘要： 随着计算机技术和无线网络技术的进一步发展,移动计算环境下的应用也越来越普及.数据量和处理复杂度不断增加,移动应用要求在移动设备上有合适的DBMS来管理.嵌入式移动数据库就此孕育而生,它可针对移动商务的要求而定制,是移动计算环境下基于数据库应用的基础和核心.事务处理是数据库管理的一个基本功能.在移动计算环境下,无线网络连接的断接性、上行和下行网络链路的不对称性以及终端的移动性和资源的有限性,都给传统的事务处理带来了新情况,提出了新的挑战.在研究国内外文献和原型的基础上,并且在仔细分析目前移动应用最终需求的前提下,该文结合我们项目小组开发的,嵌入式移动数据库管理SwiftDB,提出了基于代理层的三层结构模式来处理移动事务,由代理层的功能屏蔽终端的移动性.第三章和第四章对此做了详细的探讨并介绍了SwiftDB中同步管理模块对此的实现.移动设备内存资源有限,该文结合Windows CE内存管理的特点,在第五章中首先探讨了各种优化内存的方法及其对事务处理的影响;接着分析了如何优化移动设备上用户控制界面等问题;最后简单介绍了在移动计算环境下的数据库应用必须面对一系列的安全问题.这些都结合SwiftDB系统的实现做了相应的描述.在SwiftDB的实现中做到了尽可能优化系统的各项性能,实现系统的自动配置,提高事务处理能力.

关键词： channel allocation   mobile computing   simulated annealing   wireless networks  

摘要： A mobile network is a distributed communication system that uses radio signals as its information medium. Since the popularization of mobile networks, the rate of connectivity has soared and the subsequent load on the networks is much more significant than original projections. Hence, resource management becomes an important issue when designing mobile networks. This work concentrates on the most important resource available to mobile networks, that is, the limited allocated bandwidth. With the given amount of bandwidth, the network is expected to meet a minimum quality of service, to provide subscribers with access to the network. As the network is based on a cellular design, the way to improve utilization of the bandwidth is to reuse frequencies or channels. However, this reuse comes at a cost. The allocation of reused channels must be subject to the avoidance of interference between allocated channels. This is known as the channel allocation problem (CAP). It will be shown that the problem can be formalized into an optimization problem, for which there are many solution methodologies. In order to meet the demands of solution quality and algorithm efficiency, the decision of which method to use is critical. Biologically inspired techniques provide effective search strategies that enable the discovery of near optimal solutions. They are ideal for problems with large and complex solution spaces such as the CAP. However, the performance of these algorithms in terms of solution quality and efficiency varies greatly with the problems to which they are applied. This work makes an assessment of the application of the simulated annealing for finding optimal solutions to the CAP for a fixed or static allocation of channels. Simulated annealing is based on the annealing process employed to enhance the strength of malleable materials. It provides unique search characteristics that allow the solution space to be searched without the difficulties of other random search methods

关键词： distributed object computing   mobile communication   invocation semantics   adaptive programming  

摘要： The widespread use of wireless and mobile networks and devices requires special programming techniques and solutions. The object request brokers of mobile environments have to adopt these techniques and offer services dealing with the problems of mobility. Most of the existing object request brokers however were developed for fixed networks assuming reliable transport protocols (mostly TCP), while the mobile networks cannot offer high quality transport. In this paper we give an overview of the challenges and solutions in mobile computing and present our ORB(M) framework implementing services based on the solutions. Extending the framework doesn't require the assistance of its developers, the user can implement application-specific semantic elements and deploy various new methods bound to the process of remote invocation. The user can form arbitrary new invocation semantics based on these elements and customise the invocation semantics used by a given method. Our new mobility-related semantic elements offer solutions to the challenges of mobility allowing the user to concentrate on the essential problems of the application and handling.

关键词： effective polarizability   line widths and line shifts of H2O  

摘要： The expressions for the second-order rotational correction terms of the effective polarizability operator of asymmetric rotors have been derived using the method of contact transformation. The correction terms have been calculated for the H2O molecule. The influence of the rotational contributions on the halfwidths and shifts of some selected lines of H2O perturbed by the atoms of inert gases and N-2 molecule is investigated. (C) 2003 Elsevier Science B.V. All rights reserved.

关键词： 地理信息系统   移动计算   空间定位信息服务  

摘要： 计算机与通信技术使得移动计算成为当今一种主流计算方法 ,基于移动计算的地理信息系统 (称做移动 GIS)就是在这种条件下产生的。可以预见 ,移动地理信息系统将会是 GIS产业发展的下一个亮点。本文用 GIS发展的观点叙述了移动GIS发展的必然性 ,以及移动 GIS发展过程中的变化和特点 ,并且讨论了移动

关键词： 嵌入式系统   嵌入式移动数据库   移动计算  

摘要： 本文介绍了用于移动计算、数据检索和查询的嵌入式移动数据库的基本概念、基本特征,论述了嵌入式移动数据库的关键技术、应用解决方案及其在各领域中的广泛应用。