RDF数据存储模式研究及实现

随着Web信息呈指数级增加,目前存储模式已难以适应大规模RDF数据高效存储的需求.本文通过分析比较现有的存储模式,提出一种基于关系数据库的RDF数据存储模式,根据RDF数据特点,将RDF数据中的各个关系分解,分别存储在不同的关系表中.实验结果表明,该模式提高了RDF数据存储效率,而且具有良好的可扩展性,适用于大规模RDF数据的存储.     

基于RDF的Web挖掘系统框架设计与实现

利用RDF语义性特点，结合ASP和DOM等中间件技术进行数据预处理，在此基础上提出一种基于RDF技术的Web数据挖掘系统框架，并给出系统框架实现策略，为解决Web数据挖掘所遇到的难题提供有效途径。     

Towards an information retrieval language based on a relational view of data

Among the problems associated with modern information retrieval systems is the lack of any systematic approach to the design of query language interfaces. In this paper we attempt to show how a relationally organised data base is well suited to bibliographic data management, and how, given such a relational organisation it is possible to construct an interface which separates the query language from the physical representation of the data base. It is also shown how such a query language organisation may be usefully interfaced to existing retrieval systems. Finally a query language for retrieval applications is proposed.     

基于资源描述框架的图书馆科学数据组织初探

MARC等传统信息描述方式不适用于科学数据组织。RDA可描述各类型信息资源,基于资源描述框架理论,构建科学数据资源描述框架模型,包括科学数据集描述、数据集一数据文档描述、数据集一访问描述等,为图书馆应用RDA组织和管理科学数据提供基础。     

Cardinality estimation in numeric on-line databases

Numeric on-line databases (NDBs) have become essential in information retrieval (IR). NDBs differ from traditional bibliographic databases (BDBs) with respect to their content, structural complexity, data manipulation capabilities and the complexity of the user interfaces and user charging schemes. Recent trends in user charging for all on-line IR are toward charging for the information actually retrieved from the database rather than for the connect-time. However, the viability of such charging schemes depends on the user's possibilities of estimating the charges in advance, during the query negotiating phase. The problem of advance charge estimation in NDBs is addressed in this paper. In order to solve this problem, a method for estimating the numbers of data items satisfying the query expressions, i.e. the query cardinalities, is required. In this paper, an approach for advance estimation of query charges is developed and, based on it, a systematic and general method for query cardinality estimation is defined. The approach and the method are based on the well-known relational data model (RDM). The method is adapted to the new application area, user charge estimation in NDBs, and provides several improvements with respect to earlier cardinality estimation methods. Based on the method, several types of user charges can be estimated in advance. Tools based on the method are necessary components of query interfaces to NDBs if non-connect-timebased charging is used. The approach and the method are directly applicable to RDM-based NDBs.     

基于网络新闻语料的公共危机事件知识图谱构建

【目的/意义】本文提出了借助知识图谱的知识互联和可视化分析等功能,为公共危机事件智能治理提供知 识支撑的观点。【方法/过程】以“港独”为例,从新华网、人民网、中国新闻网等“港独”新闻语料中抽取实体,构建公 共危机事件知识图谱模型。从知识图谱本体构建和实体数据填充两个方面,对“港独”知识图谱的实体抽取、关系 抽取、知识融合、知识加工和知识推理等构建环节进行重点论述和实践,最后,利用Neo4j数据库实现知识存储,生 成的“港独”知识图谱。【结果/结论】通过Cypher语句对“港独”知识图谱进行查询,能够呈现可视化语义网结构图, 利于知识隐重发现。【创新/局限】本文的创新之处在于把知识图谱技术应用于公共危机事件治理中,为其智能查 询和决策分析提供数据支持。在今后实践中,数据源的选取不必局限于网络新闻语料,还可以适当对“港独”人员 的微博、微信、论坛中的信息进行采集和抽取,以此扩大知识关联,从而更为全面、高效地进行公共危机事件智能 治理。     

A common interface for accessing document retrieval systems and DBMS for retrieval of bibliographic data

Due to their ready availability, database management systems are being applied to bibliographic databases with increasing frequency. This is being done in spite of the fact that although DBMS query languages tend to be very powerful, they are far too complex for the casual user. It is proposed that PSI, an existing virtual-system intermediary for document retrieval systems, be extended to include access to DBMS containing bibliographic data in order to circumvent the complexity problem or the casual user. PSI currently provides a common command language for access to multiple document retrieval systems. It is shown that PSI could be extended to provide this same command language to access DBMS, whether the DBMS are relational or network.     

LABRADOR: Efficiently publishing relational databases on the web by using keyword-based query interfaces

A vast amount of valuable information, produced and consumed by people and institutions, is currently stored in relational databases. For many purposes, there is an ever increasing demand for having these databases published on the Web, so that users can query the data available in them. An important requirement for this to happen is that query interfaces must be as simple and intuitive as possible. In this paper we present LABRADOR, a system for efficiently publishing relational databases on the Web by using a simple text box query interface. The system operates by taking an unstructured keyword-based query posed by a user and automatically deriving an equivalent SQL query that fits the user’s information needs, as expressed by the original query. The SQL query is then sent to a DBMS and its results are processed by LABRADOR to create a relevance-based ranking of the answers. Experiments we present show that LABRADOR can automatically find the most suitable SQL query in more than 75% of the cases, and that the overhead introduced by the system in the overall query processing time is almost insignificant. Furthermore, the system operates in a non-intrusive way, since it requires no modifications to the target database schema.     

关系数据库查询优化策略研究

作为数据的承载平台,数据库在各行各业都得到了广泛应用。查询操作是数据库管理系统最重要的功能之一,使用频率最高。以关系型数据库为基础,从不同的角度出发,对数据库查询优化策略进行了研究。     

云计算环境下NOSQL数据库技术及应用研究

目前关系型数据库在云计算的平台下已经成为制约整个Web架构敏捷性和扩展性的瓶颈,而NoSQL可扩展的松耦合类型数据模式,以及在易用性、高度伸缩性、支持海量数据等方面所表现出来的优点,使其在云计算领域被广泛应用。分析了NoSQL数据库技术特点,并对目前应用的几种典型NOSQL数据库进行了分析比较。     

RDF可视化软件Isaviz的应用研究

RDF是一个开放的元数据框架,文章在对RDF做了简要的介绍之后。引出了RDF可视化软件Isaviz,这是一个可视化的RDF浏览和编辑工具。文章简要介绍了Isaviz的下载、安装和正确配置等,最后使用Isaviz创建了一个RDF数据模型,并给出了相应的RDF／XML代码。     

数字校园网络教学资源建设中RDF/XML的应用研究

本文首先介绍了RDF和XML,并且基于RDF/XML实现数字校园网络的教学资源建设.研究表明,RDF/XHL在教学资源数据共享中具有十分广阔的应用前景.     

RDL:一个基于RDF的数字图书馆

文章介绍了一个基于RDF的数字图书馆RDL,并重点介绍了其中的RDF数据的存储与查询,为了达到最优存储查询效率,RDL采用前向推理和后向推理结合的推理策略;前向推理导致RDF数据之间的依赖性,并且RDFS推理规则本身存在循环依赖的问题,本文给出一个算法解决了这些问题.     

常识知识查询

给出了在一个面向Agent、本体和关系的常识知识库中如何实现常识知识查询的过程。在查询过程中,用自然语言形式描述的查询先被转化成一种我们所定义的面向Agent和本体的描述性查询语言。接着,描述性查询被翻译成SQL查询语句。用SQL查询语句对已转化成为关系形式的常识知识库进行查询后,自然语言生成算法把以关系表为形式的查询结果转化成自然语言。实验表明,新的查询方法在查询时间上优于原有的直接在agent和本体上查询知识的旧方法。实验数据表明,查询时间缩短了大约80 %。     

湖州市台风查询系统及其应用前景

简介了湖州台风服务系统的资料整编及查询检索过程,各模块的结构及原理和链接关系．提供了详细的检索方法,基于GPS（global positioning system）和GIS（geographical information systems）本系统以资料套用的方式将全国的台风资料与影响浙江和湖州市的台风资料有机地互相引用,达到资源共享的目的,既可以及时了解分析全国乃至西太平洋、南海台风的活动情况．以便及时掌握台风可能对浙江、湖州的侵害。又可在需要查询台风可能对湖州带来的灾害时,直接进行沏州台风模块的检索．进行历史资料路径、风雨、影响时间、危害程度的对比,因此本系统资料翔实、项目齐全、模块分类清晰、链接查询方便。     

基于Hibernate的数据持久化应用研究

Hibernate是一个对象持久化工具,它通过其强大的O/R映射功能将Java对象同存放于关系数据库中的数据进行映射,避免了开发人员使用大量的SQL语句通过JDBC的方式对数据库进行操作,可以有效地提高开发的效率。将其应用于企业在线资产管理系统,可充分利用其优点。     

A comparative study of multiple attribute tree and inverted file structures for large bibliographic files

A variety of data structures such as inverted file, multi-lists, quad tree, k-d tree, range tree, polygon tree, quintary tree, multidimensional tries, segment tree, doubly chained tree, the grid file, d-fold tree. super B-tree, Multiple Attribute Tree (MAT), etc. have been studied for multidimensional searching and related problems. Physical data base organization, which is an important application of multidimensional searching, is traditionally and mostly handled by employing inverted file. This study proposes MAT data structure for bibliographic file systems, by illustrating the superiority of MAT data structure over inverted file. Both the methods are compared in terms of preprocessing, storage and query costs. Worst-case complexity analysis of both the methods, for a partial match query, is carried out in two cases: (a) when directory resides in main memory, (b) when directory resides in secondary memory. In both cases, MAT data structure is shown to be more efficient than the inverted file method. Arguments are given to illustrate the superiority of MAT data structure in an average case also. An efficient adaptation of MAT data structure, that exploits the special features of MAT structure and bibliographic files, is proposed for bibliographic file systems. In this adaptation, suitable techniques for fixing and ranking of the attributes for MAT data structure are proposed. Conclusions and proposals for future research are presented.     

基于关系约束的XML元素近似查询研究

近年来,XML已成为信息表示、交换和发布的标准,因此,XML数据查询已成数据库(DB)和信息检索(IR)领域广发研究的问题。XML通常被视为一个标签树,常用的方法是近似查询。由于在用户查询通常有一定的关系约束出现,在分析了用户查询对XML元素和值关系约束之后,本文提出了使用关系约束近似提取XML元素的方法