模式数据库在智能规划中的应用

该规划器通过对智能规划领域里传统的构造模式数据库的方法进行改进,从而改进模式数据库启发式的效率：通过分析和移除一些在实际问题空间里不可能存在对应的完整状态的模式有效地减少了模式数据库的构造时间,并提高了模式数据库启发值的紧致性,使得模式数据库启发式能更好的指导搜索算法以求得问题的最优解。该规划器在linux系统下设计,通过使用规划器解决积木世界领域的规划问题来研究改进前后模式数据库启发式在搜索过程中所起的作用。     

A Sequence-Based Object-Oriented Model for Video Databases

Structuration, annotation and composition are amidst the most crucial modeling issues that video editing and querying in the context of a database entail. In this paper, we propose a sequence-based, object-oriented data model that addresses them in an unified, yet orthogonal way. Thanks to this orthogonality, the interactions between these three aspects are properly captured, i.e., annotations may be attached to any level of video structuration, and all the composition operators preserve the structurations and annotations of the argument videos. We also propose to query both the structuration and the annotations of videos using an extension of ODMG's OQL which integrates a set of algebraic operators on sequences. The overall proposal is formalized and implemented on top of an object-oriented DBMS.     

KWSDS:关系数据库中Top-k关键词搜索系统

关系数据库中的关键词搜索技术已经成为信息检索领域的研究热点,它为没有任何SQL语法知识的用户提供了一个简单友好的接口.但是现存的关键词搜索系统主要依赖于数据图或模式图,而单独使用数据图或模式图的算法搜索效率不高,结果准确率也较低.设计实现了一个Top-k关键词搜索系统(keyword search system based on database graph and schema graph,KWSDS),用户提交关键词后,系统对关键词进行预处理,消除一些脏关键词.首次提出使用数据图与模式图相结合的方法,设计了同表查询算法和异表查询算法,分析了算法的正确性和时间复杂度,并且提出了相关性结果排序方法.KWSDS系统的搜索算法运行时间短,搜索结果准确性高,具有良好的查询性能.最后通过实验验证了KWSDS的效率.     

Survey of Spatio-Temporal Databases

Spatio-temporal databases aim to support extensions to existing models of Spatial Information Systems (SIS) to include time in order to better describe our dynamic environment. Although interest into this area has increased in the past decade, a number of important issues remain to be investigated. With the advances made in temporal database research, we can expect a more unified approach towards aspatial temporal data in SIS and a wider discussion on spatio-temporal data models. This paper provides an overview of previous achievements within the field and highlights areas currently receiving or requiring further investigation.     

高效的稀有序列模式挖掘方法

序列模式挖掘是数据挖掘领域的一个经典研究问题,目前的研究主要关注于频繁序列模式的挖掘。但是不频繁的序列模式,即“稀有序列模式（rare sequential pattern,RSP）”也可能蕴含着一些不寻常的规律,具有更高的挖掘价值。因此,给出了稀有序列模式挖掘的定义,并且提出了两种逐层挖掘稀有序列模式完全集的方法。为克服挖掘稀有序列模式全集时产生的组合爆炸问题,提出了一种高效的基于二分查找的算法来挖掘“最小稀有序列模式（minimal rare sequential pattern,MRSP）”全集,它包含了稀有序列模式全集的完整信息。通过实验验证了提出的算法可以有效地挖掘稀有序列模式。     

Constraints in Databases

Recently, interest in constraints and databases has increased significantly as the databases field has started to consider broader application domains. In this short position statement, I identify some of the most promising direcrtions, in my opinion, for the use of constraints in the context of databaes management systems.     

关系数据库中支持语义的Top-K关键字搜索

为了增强关系数据库中的关键字搜索查询结果,考虑了多表之间以及元组之间的语义关系,提出了一种语义评分函数.该语义评分函数不仅涵盖了当前的评分思想,并且加入新指标来衡量查询结果与查询关键字之间的相关性.基于该评分函数,提出两种以数据块为处理单位的Top-K搜索算法,分别为BA(blocking algorithm)算法和EBA(early-stopping blocking algorithm)算法.EBA在BA基础上引入了过滤域值,以便尽早终止算法的迭代次数.最后实验结果显示语义评分函数保证了搜索结果的高查准率和查全率,所提出的BA算法和EBA算法改善了现有方法的查询性能.     

SIOC化学数据库的网络化进展

介绍了ＳＩＯＣ上网的４个化学数据库,包括两个化工企业和厂商数据库,一个化学文献数据库和一个红外光谱数据库。     

基于Hadamard变换的高维图像检索方法

传统索引方法对高维数据进行近邻搜索时会面临维数灾难问题,向量近似方法是一种有效的高维检索方法。提出一种 Hadamard 变换域上的向量近似方法,在变换域能量最大的分量上建立顺序索引,然后建立近似向量文件。同时提出低維过滤算法,可以在近邻搜索过程中高效排除不匹配近似向量,减少 I/O 访问时间,提高查询效率。在大型高维图像特征库上的实验表明,该方法性能优于小波变换域的向量近似方法。     

A Graphical Navigator for viewing Databases

This paper describes the architecture and implementation of Graphical Navigator, a system for visualizing and querying databases. The schema of a database is represented by classes and associations between the classes. Thus, a database is viewed as a labeled graph. A graphical query notation was developed to query databases. The query notation allows formulation of recursive and predicated queries. The system facilitates incremental querying by way of workspaces. The formulation, execution and incremental querying are all done in a highly interactive and visual environment.     

面向对象数据库系统中的查询执行规划生成

本文首先定义了一个对象管理器接口，它由一系列操作组成，而查询执行规划就是以接口中的这些操作作为基本可执行单元。根据面向对象数据库查询的具体特点，我们提出了一个为基于对象代数表示的查询生成相应查询执行规划的算法，该算法能快速地生成查询执行规划。     

Constraint Databases: Promising Technology or Just Intellectual Exercise?

This paper describes the state of Constraint Databases (CDBs), a young discipline at the intersection of Database Management, Constraint Programming, Computational Geometry and Operations Research. As in Constraint Logic Programming, constraints in CDBs are a first class data type, and can play many modeling roles including spatial and temporal behavior, complex design requirements, and partial and incomplete information, for which existing databases have proven inadequate. We motivate the importance of CDBs, outline the work in the area that has been done, the current trends, and future directions and challenges. We briefly discuss (1) constraint modeling, canonical forms and algebras, (2) data models and query languages, (3) indexing and approximation-based filtering, (4) constraint algebra algorithms and global optimization, and (5) systems and case studies. We argue that CDBs are a promising technology that will impact many important application realms, and furthermore have the potential to be integrated into future database systems, and operations research and constraint programming tools.     

约束优化模式搜索法研究进展

实际工程应用中的优化问题通常包含复杂的约束条件,其目标函数可能是非线性、非连续、不可微甚至随机函数;而约束函数可能是线性、非线性、离散变量集,甚至黑盒函数(例如,由程序代码生成的值集合);约束变量也可能是包含连续、离散或分类值的混合变量.这些复杂的情况,使得没有任何导数/梯度信息可供利用,因此无法利用现有的凸优化技术求解.文中研究如何利用模式搜索法对常见的混合变量约束优化模型进行求解.首先对直接搜索法的发展历史进行概述;特别地,给出模式搜索法统一的数学描述和收敛性分析.对约束条件从无约束(一般模式搜索)到线性约束(广义模式搜索GPS)、非线性约束(GPS过滤法)和混合约束(广义混合变量规划GMVP)的推广以及在边界约束条件下,算法搜索方向从有限集向紧致集的扩展(网格自适应直接搜索MADS),进行了全面分析;在此基础上对该领域尚存在的问题及进一步的研究方向进行了总结.     

A Framework for Cache Management for Mobile Databases: Design and Evaluation

In a mobile computing environment, database servers disseminate information to multiple mobile clients via wireless channels. Due to the low bandwidth and low reliability of wireless channels, it is important for a mobile client to cache its frequently accessed database items into its local storage. This improves performance of database queries and improves availability of database items for query processing during disconnection. In this paper, we investigate issues on caching granularity, coherence strategy, and replacement policy of caching mechanisms for a mobile environment utilizing point-to-point communication paradigm.We first illustrate that page-based caching is not suitable in the mobile context due to the lack of locality among database items. We propose three different levels of caching granularity: attribute caching, object caching, and hybrid caching, a hybrid approach of attribute and object caching. Next, we show that existing coherence strategies are inappropriate due to frequent disconnection in a mobile environment, and propose a cache coherence strategy, based on the update patterns of database items. Via a detail simulation model, we examine the performance of various levels of caching granularity with our cache coherence strategy. We observe, in general, that hybrid caching could achieve a better performance. Finally, we propose several cache replacement policies that can adapt to the access patterns of database items. For each given caching granularity, we discover that our replacement policies outperform conventional ones in most situations.     

基于实时日志的嵌入式实时数据库恢复策略

在分析嵌入式实时数据库数据和事务特征的基础上,讨论了嵌入式实时数据及事务的一致性约束,包括内部一致性、时间一致性(外部一致性和相互一致性).为满足各种一致性,针对不同类型的数据和事务给出了识时恢复的正确性准则.基于这些约束,设计了实时日志及相应的恢复算法.性能分析结果表明,所给出的恢复方法在减低超截止期事务比率、节省系统开销等方面都具有较好性能.     

Object-Oriented Databases with Relational DBMSs

The expediency of the use of object-oriented models of data as datalogical models in designing databases is shown, and methods of integration of relational and object-oriented models are considered. A relational scheme for storage of attributes and relations of object-oriented models is proposed.     

生物化学分子数据库分析和设计研究

讨论了在新药物发现与设计中化学分子数据库的设计和应用这一较新的应用领域,通过对分子数据库结构和特征的分析,提出了一种可行的数据库的设计模型,分析了模型中的各个模块的结构和功能,讨论了数据冗余的处理和数据库的管理,并提出了一些有待解决的问题。     

关系数据库中支持语义的Top-K关键字搜索

为了增强关系数据库中的关键字搜索查询结果,考虑了多表之间以及元组之间的语义关系,提出了一种语义评分函数.该语义评分函数不仅涵盖了当前的评分思想,并且加入新指标来衡量查询结果与查询关键字之间的相关性.基于该评分函数,提出两种以数据块为处理单位的Top-K搜索算法,分别为BA(blocking algorithm)算法和EBA(early-stopping blocking algorithm)算法.EBA在BA基础上引入了过滤域值,以便尽早终止算法的迭代次数.最后实验结果显示语义评分函数保证了     

基于PVM的启发式搜索的并行计算模型设计

通过分析人工智能中的A和A^*启发式搜索,提出了通过PVM工具包,设计和实现A和A^*启发式搜索的并行计算模型。在启发搜索过程中同时进行评估函数计算,使计算的速度加快。解决了在搜索解空间庞大,评估函数计算复杂的情况下,使用单计算机计算速度慢的问题。该文实现了基于PVM的启发式搜索过程,该模型可应用于一般性启发式搜索问题的并行计算模型。     

Context-Aware Fuzzy Databases

The development of mechanisms to ease human machine interaction is an issue about which there is increasing interest within both the software world in general, and database systems in particular. A way to tackle this problem is to try to approach the natural way of user expression. The Fuzzy Sets Theory and its application to build Fuzzy Databases constitute a consolidated advance in the literature. Another way is to adapt the interaction of the system to the context where it is running. In this sense, this paper presents an approach to build a model of Fuzzy Databases that dynamically adapts to user context. In order to do this, we have studied the management of the context in Fuzzy Database applications and we propose an architecture for the development of intelligent, flexible and customized context-aware database systems. We also present a proof of concept implementation to be used with SQL:99 standard in Oracle ORDBMS. Finally, through a real application in the medical area, we demonstrate the feasibility of the proposal.