Performance Evaluation of Distributed Database Architectures for UMTS Service Deployed in an Urban Area

The design of distributed databases (DDBs) destined to store user information is a key issue in third-generation mobile communication systems such as UMTS. In particular, the problem of determining the most appropriate DDB architectures for UMTS is critical due to the anticipated requirements of high distribution and adaptability of information. This paper presents a model which allows different DDB architectures to be evaluated, in terms of query loads and average search times. The model proposed puts no constraints on either the DDB structure arrangement or the user position characterization. The paper also discusses a real, significant case study, concerning a query operation arising from an access procedure performed on the DDB of a communication network covering an urban area.     

全分布式位置管理策略的负载和位置更新性能研究

分布式位置管理策略及其分布式数据库结构与传统位置管理策略和HLR－VLR结构有显著区别，本文基于一种对DDB结构新的性能估计方法，从用户的移动性概率分布出发，对DDB结构下的数据库负载和位置更新性能进行了研究。     

分布式数据查询策略的性能估计算法

分布式数据查询策略及其结构(DDB结构),与传统的HLR-VLR结构有很大的不同.本文提出了一种对DDB结构的性能估计方法,其基础是用户的移动性和呼叫特性的概率分布.本文对DDB结构的代价和呼叫传递时延等性能参数进行了研究,证明了DDB结构的性能优越性.     

Design and evaluation of a replicated database for mobile systems

The new generation mobile systems are anticipated to provide mobile users with new broadband services such as wireless multimedia, including real‐time video and high‐speed data. In these systems, the requirement on service transparency placed by the handling of mobility, both personal and terminal, implies a remarkable increase in the complexity of data management. Therefore, appropriate distributed databases (DDB) must be designed to guarantee speed in the processing and updating of user information, and a high level of reliability and performance. In this paper we analyze a minimally replicated DDB in which different strategies for the redundancy of user data are discussed. First, we develop a Petri net based model in order to analyze the consequences on dependability deriving from faults in nodes at different levels in the DDB structure. Then, we investigate the performance offered by the system through a queueing network model. The measures of interest include reliability, availability, mean time to failure, and mean response time to service access. This revised version was published online in August 2006 with corrections to the Cover Date.     

软件质量平台中关联规则挖掘的应用

本文介绍了软件质量平台中关联规则挖掘的应用,利用关联规则挖掘的原理,将其运用到软件开发过程中,依据大量的客观数据来支持关联规律,提高规律的可信度。根据规模、配置申请、风险问题、错误缺陷、小组士气、任务进度六种属性来测量关联规则。     

Spontaneous Group Management in Mobile Ad Hoc Networks

This paper deals with the problem of Location Management in mobile ad hoc networks where users are organized in groups. In the following this type of systems are referred to as Mobile Ad hoc Networks for Group Operations (MANGO). This paper proposes a framework for location management which exploits the trend of mobile users to spontaneously form groups in MANGOs. The management procedures required to support such spontaneous groups, which are by nature dynamic, are introduced as well. The proposed spontaneous group management is based on a hierarchical location database architecture and the concept of Group Leader, which is a terminal responsible for the location update of a group of terminals. Objective of the proposed framework is minimizing the burden on location databases and, at the same time, the signaling issued by terminals. In this paper, distributed operations required to support the whole framework are properly introduced and described. Simulation experiments have been run in order to assess the proposed scheme. Performance results show that the introduced methodology allows reduced signaling and location updating.     

个性化搜索中一种基于位置服务的隐私保护方法

在基于位置服务的个性化搜索中,利用可信第三方服务器以及对等节点是保护用户隐私的主要方法,但在现实生活中,它们却是不完全可信的。为了解决这一问题,该文提出一种个性化搜索中基于位置服务的隐私保护方法。该方法通过转换用户的位置信息,并根据用户的查询类型生成用户模型,进而形成带有用户位置信息的查询矩阵,然后利用矩阵加密用户的查询,隐藏查询矩阵中的用户信息,最后根据安全内积计算返回相关性得分最高的前K个查询文件给用户。安全性分析表明该方法能有效地保护用户的查询隐私和位置隐私,通过分析与实验表明,该方法大幅度地缩短了索引构建时间,降低了通信开销,同时为用户提供了基于位置的个性化搜索结果,一定程度上解决了移动设备屏幕小带来的弊端。     

Introduction to the Special Issue on Communication Issues in User–Database Interaction

Research on user–database interaction studies the communication issues among users with various roles, such as end-user, requirement analyst, database designer, query programmer, as well as between users and databases through various database management systems. Many topics are included. Common topics include the formal languages used in database models and queries, with focus on designer and user writing effectiveness and efficiency, as well as end-user comprehension and problem solving capabilities. Research results are generally applicable to the communication processes for users, user training, and the design of database management systems, such as query interfaces and choice of database models.     

The Role of Artificial Intelligence in the Integration of Remotely Sensed Data with Geographic Information Systems

Although databases for geographic information systems (GIS) have been developed to manage digital map data, the integration of remotely sensed imagery and other collateral non-map information is rarely performed. For the most part, the use of sophisticated intelligent spatial databases, in which the user can query interactively about map, terrain, or associated imagery, is unknown in the GIS and cartographic community. In standard GIS systems, the ability to formulate complex queries requiring dynamic computation of factual and geometric properties is severely limited, often reflecting its origin as collections of thematic map overlays. Spatial database research requires the integration of ideas and techniques from many disciplines such as computer graphics, computational geometry, database methodology, image analysis, photogrammetry, and artificial intelligence. In this paper we discuss some ideas on how the scope of geographic information systems can be expanded by utilizing techniques from the Al community that may remedy deficiencies in user interfaces, spatial data representation, and its utilization. We draw on ongoing research at Carnegie Mellon University for examples of these techniques in the areas of image/map database and knowledge-based image interpretation.     

城市公交查询系统的设计

以城市的实际情况对公交查询系统进行研究,对详细的问题定义与用户需求进行合理的设计,并实现了面向用户的城市公交信息系统.本系统前台开发用JAVA语言,后台管理用MySQL数据库.系统主要包括线路查询功能、站点查询功能、换乘查询功能、留言板功能,以方便用户更便捷地查询到所需乘坐的车次,从而节约出行时间.     

DB2数据库查询优化策略

数据库的查询优化是改善应用程序性能的重要手段。通过分析IBM DB2数据库系统的最优化处理器的工作原理,对查询性能影响较大的统计信息更新、索引建立、SQL查询语句构造3个方面提出具体优化建议。建立了一套完整的测试方案,对每一条优化建议都使用具体SQL语句进行严格的验证。开发者要注意分析查询语句的时间开销和空间开销,才能写出较优的查询语句。     

基于代理的移动数据库研究

近年来,无线技术的发展促进了移动计算的研究,但是多数移动数据库系统使用传统的客户机/服务器模式或单代理模式处理移动查询,进而产生了数据大量迁移的问题。文章提出了一种基于多移动代理技术的移动数据库查询处理模型,旨在减少处理过程中的数据迁移量,提高移动环境下查询分布式异构数据库的性能。     

Mobility modeling, location tracking, and trajectory prediction inwireless ATM networks

Wireless ATM networks require efficient mobility management to cope with frequent mobile handoff and rerouting of connections. Although much attention has been given in the literature to network architecture design to support wide-area mobility in public ATM networks, little has been done to the important issue of user mobility estimation and prediction to improve the connection reliability and bandwidth efficiency of the underlying system architecture. This paper treats the problem by developing a hierarchical user mobility model that closely represents the movement behavior of a mobile user, and that, when used with appropriate pattern matching and Kalman filtering techniques, yields an accurate location prediction algorithm, HLP, or hierarchical location prediction, which provides necessary information for advance resource reservation and advance optimal route establishment in wireless ATM networks     

人类SNP数据查询平台的开发与优化

单核苷酸多态性（SNP,Single Nucleotide Polymorphism）作为重要遗传标记,在遗传学研究中得到了广泛关注。针对从海量人类基因数据中获取SNP信息并实现数据共享的问题,本文构建了基于Web的SNP数据查询平台并进行性能调优。该数据库系统用户界面友好,数据查询操作简单且能够快速查询SNP数据,实现了SNP数据实时查询和共享,一定程度上解决了许多小型实验室以及非生物专业研究人员所面临的问题,为后续算法研究和软件开发提供了有力帮助。     

The Application Model of Moving Objects in Cargo Delivery System

Consider a database that represents and manages the information about moving objects and their locations such as the material delivery system, the communication is vital and constant among the database (delivery center), the moving objects (the material on road) and database application users (the owner of the material). We need to establish the new model for moving objects such as location model, indexing, dynamic attributes, spatial and temporal query, etc. in database management system (DBM…     

VFP中通用查询的实现

数据查询是数据库信息管理系统的重要功能。而通用查询程序具有良好的数据界面，用户可以选取任意输出字段，设置关于任意字段的查询条件；而且在实例值的输入时不必输入定界符，实现数据类型的自动匹配。同时也可以方便地移植到其他的数据库信息管理系统中。     

基于用户数据字典的通用动态查询组件的研究与实现

为了提高管理信息系统中查询的通用性，解决系统应用程序对具体数据库结构及开发语言依赖性过大的问题．本文介绍了一种基于用户数据字典的通用动态查询的设计与实现方法，利用组件技术封装了数据库接口、查询功能和用户数据字典维护功能，使查询更加灵活、易操作，并可以在不同数据库和开发语言环境下应用，提高了软件的复用性及系统开发的效率，文末给出了具体的应用。     

Architecture and enablers for optimized radio resource usage in heterogeneous wireless access networks: The IEEE 1900.4 Working Group

Over the past decade or so, the wireless industry has undergone many significant changes. Radio systems have moved toward forming heterogeneous wireless networks: collaborations of multiple radio access networks, which in some cases operate different radio access technologies, such as second- and third-generation cellular RATs, IEEE 802.x wireless standards, and so on. On the other hand, multimode reconfigurable user devices with the ability to choose among various supported RATs have become a reality, and devices and networks with dynamic spectrum access capabilities, allowing real-time sharing of spectrum resource usage among different systems, are expected to be a part of the future radio eco-space. As a result of these changes, there is a need to develop a standard that addresses the requirements and leverages the opportunities posed by such a versatile radio environment. To this end, IEEE 1900.4 aims to standardize the overall system architecture and information exchange between the network and mobile devices, which will allow these elements to optimally choose from available radio resources. In other words, the standard facilitates the distributed dynamic optimization of the usage of spectrum offered by the heterogeneous wireless network, relying on a collaborative information exchange between networks and mobile devices, thereby acting as a common means to improve overall composite capacity and quality of service for the served networks. This article provides a snapshot of IEEE P1900.4 in its current form, covering the scope and purpose of the standard, reference use cases for which the standard is applicable, its system and functional architectures, and finally, the information model for its main interfaces.