A computation-oriented multimedia data streams model for content-based information retrieval

Multimedia applications nowadays are becoming prevalent. In the past the relational database model was generalized to the multimedia database model. More recently the relational database model was generalized to the data streams model, as the technology advanced and data became bulky and unbounded in size due to the utilization of sensor networks. In this paper we take one more step of generalization by providing a multimedia data streams model. The objective is to furnish a formal framework to design multimedia data streams (MMDS) schema for efficient content based information retrieval. We also extend the functional dependency theory and the normalization framework to handle multimedia data streams. Finally we present algorithmic methods of generating continuous multimedia queries along with examples for illustration.     

次协调数据库中的域关系演算

次协调数据库的数据模型是用来处理数据库中两类不确定信息,即不完全信息和不一致信息(矛盾信息)。关系演算语言是表达关系数据模型中的数据操作的一种方式。域关系演算是以域为变量进行的关系演算。文中提出了一种4值的域关系演算来查询次协调数据库,它的语法与普通关系上的2值域关系演算相似,但是这种新的4值语义能够有效的查询不完全信息和不一致信息。这为次协调数据库中的类SQL语言及实现提供了理论依据,进而为次协调数据库的应用打下坚实基础。     

Integrating relational and object-oriented database systems using a metaclass concept

This paper presents a specific approach of integrating a relational database system into a federated database system. The underlying database integration process consist of three steps: first, the external database systems have to be connected to the integrated database system environment and the external data models have to be mapped into a canonical data model. This step is often called syntactic transformation including structural enrichment and leads to component schemas for each external DBMS. Second, the resulting schemas from the first step are used to construct export schemas which are then integrated into global, individual schemas or views in the third step. In this paper we focus on the first step for relational databases, i.e., the connection of a relational database system and the mapping of the relational model into a canonical data model. We take POSTGRES as the relational database system and the object-oriented federated database system VODAK as the integration platform which provides the open, object-oriented data model as the canonical data model for the integration. We show different variations of mapping the relational model. By exploiting the metaclass concept provided by VML, the modelling language of VODAK, we show how to tailor VML such that the canonical data model meets the requirements of integrating POSTGRES into the global database system VODAK in an efficient way.     

基于内容的多媒体数据库系统引擎CDB

CDB(Content-based DataBase)是一种基于内容的多媒体数据库引擎，可以嵌入到通用的对象一关系数据库中，使数据库系统综合支持对多媒体数据的常规和基于内容的壹询．本文首先阐述CDB的体系结构，它把信息检索和数据检索结合到数据库中，支持多媒体数据库的基于内容的建立、操纵和维护；然后给出其层次型内容模型，描述多媒体内容的时空结构特征以及信息线索；最后描述用于CDB的基于内容信息检索技术及其设计和实现的用户壹询和操纵接口，包括示例壹询、主观颜色壹询、视频概要和浏览、扩展SQL内容壹询等．     

Information source tracking method: efficiency issues

This paper is devoted to the study and analysis of query processing efficiency in the information source tracking (IST) technique, an approach to the representation and manipulation of uncertain and inaccurate data. We show that the efficiency depends on the average number of information sources confirming the same data in the database. If this number is close to unity, then the efficiency of query processing for the IST model is comparable to conventional relational database systems. For the case where multiple information sources confirm the same data in the database, we present a variation of IST, called the Dual IST method, which provides efficient query processing. Extended relational algebra operations are presented for Dual IST, and proven to be correct under the “alternate worlds” semantics interpretation. The complexity of reliability calculation in IST and Dual IST methods is also studied     

Uncertainty in a nested relational database model

Some database models have already been developed to deal with complex values but they have constrains that data stored is precise and queries are crisp. However, as many researchers have pointed out, there is a need to present, manipulate, and query complex and uncertain data of various non-traditional database applications such as oceanography, multimedia, meteorology, office automation systems, engineering designs, expert database systems and geographic information systems. In this paper, we present a logical database model, which is an extension of a nested relational data model (also known as an NF² data model), for representing and manipulating complex and uncertain data in databases. We also introduce a possible physical representation of such complex and uncertain values in databases and describe the query processing of the model that we discuss here.     

地理信息系统与数据库结合研究

鉴于地理信息系统需要对外提供灵活高效的地理信息访问途径,因此采用数据库管理地理信息是发展趋势,目前存在关系型,对象-关系型,面向对象型3类数据库产品,在讨论它们与地理信息系统结合可行性的基础上,重点介绍了纯关系模型,空间扩展模型,包装模型3种结合方案,还通过对这3种方案实现原理的分析及其优缺点的比较,指出了各方面的应用前景,并由此归纳出,在GIS与数据库结合中需要注意的问题及解决这些问题的关键技术。     

对象模式到关系模式转换的软件框架研究

数据在信息系统中的使用面临着这样一个困难，即数据存储是以关系模型为基础，而软件开发以对象模型来进行，造成了软件开发中数据访问技术的不和谐。在软件实现上陷入两种模式的转换工作，破坏面向对象语言的面向对象性，造成开发效率低下，代码重用率变低。提出并建立了一个软件框架，利用它提供的处于关系数据库和客户端之间的API来进行基于对象的数据库访问，充分发挥两种不同模式的优点，以提高软件开发的效率。     

基于GIS的农产品指标数据库表结构设计研究

为了将GIS(地理信息系统)有效地应用到农产品统计中,阐述了农产品指标的3种维度——属性维度、时间维度、空间维度。分析了全关系数据库模型、面向对象数据库模型、对象关系混合数据库模型对GIS数据存储的各类特点,考虑到农产品指标数据本身的特点,提出了采用关系型数据库存储GIS数据与农产品指标数据,并以此模型为基础,设计和分析了数据库物理设计中农产品指标横向与纵向存储的两种结构方案。通过测试数据验证了两者的优缺点,并提出了数据库分区和面向时间或空间维度独立建表的优化途径。     

一种基于FCA的面向关系数据库的本体学习方法

从已有的数据模型中进行语义提取,经过一定的规则映射生成本体的过程称为本体学习。关系数据库模型是当前数据的存取与组织的主要模型,从中学习得到本体,一直是本体工程领域研究的热点之一。利用手工定义的E-R模型到本体的映射规则来完成本体的构建,是国内外大部分学者采用的方法。但这样获得的本体概念层次关系主观依赖性强,不利于本体的实际应用。为了能更加客观地获取数据之间的概念层次关系与语义信息,提出了一种基于FCA(形式概念分析)从关系数据库进行本体学习的方法。该方法既保持了关系数据表中原有的数据语义关系,又发挥了FCA自动提取语义信息的特点,提高了最终本体生成的质量,有利于在具体的领域应用中使用本体。最后结合材料服役安全数据库的数据信息,演示了运用所提出的方法学习得到领域本体的过程。     

Constructing the Bayesian network structure from dependencies implied in multiple relational schemas

Relational models are the most common representation of structured data, and acyclic database theory is important in relational databases. In this paper, we propose the method for constructing the Bayesian network structure from dependencies implied in multiple relational schemas. Based on the acyclic database theory and its relationships with probabilistic networks, we are to construct the Bayesian network structure starting from implied independence information instead of mining database instances. We first give the method to find the maximum harmoniousness subset for the multi-valued dependencies on an acyclic schema, and thus the most information of conditional independencies can be retained. Further, aiming at multi-relational environments, we discuss the properties of join graphs of multiple 3NF database schemas, and thus the dependencies between separate relational schemas can be obtained. In addition, on the given cyclic join dependency, the transformation from cyclic to acyclic database schemas is proposed by virtue of finding a minimal acyclic augmentation. An applied example shows that our proposed methods are feasible.     

Handling indefinite and maybe information in logical fuzzy relational databases

In this article, fuzzy set theory uses an extension of the classical logical relational database model. A logical fuzzy relational database model was developed with the aim of manipulating imprecise information and adding deduction capabilities to the database system. The essence of this work is the detailed discussion on fuzzy definite, fuzzy indefinite, and fuzzy maybe information and the development of an information theoretical approach of query evaluation on the logical fuzzy relational database. We define redundancies among fuzzy tuples and the operator of their removal. A complete set of fuzzy relational operations in relational algebra and the calculus of linguistically quantified propositions are included also. © 2004 Wiley Periodicals, Inc.     

Storing and querying fuzzy XML data in relational databases

Information imprecision and uncertainty exist in many real-world applications and for this reason fuzzy data management has been extensively investigated in various database management systems. Currently, introducing native support for XML data in relational database management systems (RDBMs) has attracted considerable interest with a view to leveraging the powerful and reliable data management services provided by RDBMs. Although there is a rich literature on XML-to-relational storage, none of the existing solutions satisfactorily addresses the problem of storing fuzzy XML data in RDBMs. In this paper, we study the methodology of storing and querying fuzzy XML data in relational databases. In particular, we present an edge-based approach to shred fuzzy XML data into relational data. The unique feature of our approach is that no schema information is required for our data storage. On this basis, we present a generic approach to translate path expression queries into SQL for processing XML queries.     

Fuzzy rough set techniques for uncertainty processing in a relational database

This paper concerns the modeling of imprecision, vagueness, and uncertainty in databases through an extension of the relational model of data: the fuzzy rough relational database, an approach which uses both fuzzy set and rough set theories for knowledge representation of imprecise data in a relational database model. The fuzzy rough relational database is formally defined, along with a fuzzy rough relational algebra for querying. Comparisons of theoretical properties of operators in this model with those in the standard relational model are discussed. An example application is used to illustrate other aspects of this model, including a fuzzy entity–relationship type diagram for database design, a fuzzy rough data definition language, and an SQL‐like query language supportive of the fuzzy rough relational database model. This example also illustrates the ease of use of the fuzzy rough relational database, which often produces results that are better than those of conventional databases since it more accurately models the uncertainty of real‐world enterprises than do conventional databases through the use of indiscernibility and fuzzy membership values. ©2000 John Wiley & Sons, Inc.     

Constraint Preserving Transformation from Relational Schema to XML Schema

XML has become the standard for publishing and exchanging data on the Web. However, most business data is managed and will remain to be managed by relational database management systems. As such, there is an increasing need to efficiently and accurately publish relational data as XML documents for Internet-based applications. One way to publish relational data is to provide virtual XML documents for relational data via an XML schema which is transformed from the underlying relational database schema such that users can access the relational database through the XML schema. In this paper, we discuss issues in transforming a relational database schema into the corresponding XML schema. We aim to preserve all integrity constraints defined in a relational database schema, to achieve high level of nesting and to avoid introducing data redundancy in the transformed XML schema. In the paper, we first propose a basic transformation algorithm which introduces no data redundancy, then we improve the algorithm by exploring further nesting of the transformed XML schema.     

粗糙关系数据库空间结构及其粗糙集模型

粗糙关系数据库模型从本质上来说就是多值信息系统,它继承和扩展了经典的粗糙集理论,但与经典粗糙集理论又有着很大的不同。该文扩展了多值信息系统模型的定义,分析了粗糙关系数据库模型的空间结构,为粗糙数据库的不确定性进行度量提供一个依据,同时通过对粗糙关系数据库空间结构的分析,导出了基于粗糙关系数据库的上、下近似以及值约简,进一步基于粗糙关系数据库的空间结构定义了属性集之间的部分、传递依赖关系和粗糙关系数据库的规范,定义粗糙关系数据库的连接算子,并以此为基础得出了粗糙关系数据库的关系模式分解定理,为粗糙关系数据库模型的进一步研究提供了理论基础。     

一种模仿XML的灵活的关系数据库设计

该文针对传统关系数据库设计难以应对数据模型变化的缺点,借鉴XML技术中的文档结构和数据组织的方式,设计一个具有灵活性、可扩展性的,可以在不修改数据库表结构条件下方便的应对数据模型变化的关系数据库,并使其可以方便的与XML进行相互转换,以使其更适应面向对象的技术要求。     

An algebra for probabilistic databases

An algebra is presented for a simple probabilistic data model that may be regarded as an extension of the standard relational model. The probabilistic algebra is developed in such a way that (restricted to α-acyclic database schemes) the relational algebra is a homomorphic image of it. Strictly probabilistic results are emphasized. Variations on the basic probabilistic data model are discussed. The algebra is used to explicate a commonly used statistical smoothing procedure and is shown to be potentially very useful for decision support with uncertain information     

对象模式到关系模式转换的软件框架研究

数据在信息系统中的使用面临着这样一个困难,即数据存储是以关系模型为基础,而软件开发以对象模型来进行,造成了软件开发中数据访问技术的不和谐。在软件实现上陷入两种模式的转换工作,破坏面向对象语言的面向对象性,造成开发效率低下,代码重用率变低。提出并建立了一个软件框架,利用它提供的处于关系数据库和客户端之间的API来进行基于对象的数据库访问,充分发挥两种不同模式的优点,以提高软件开发的效率。     

PostgreSQL数据库运行状态数据的统计收集机制分析

对象关系数据库是新一代的数据库管理系统,它将关系数据库系统与面向对象数据库系统两方面的特征相结合,不仅能很好地支持对象管理和规则管理,而且能更好地支持原有的关系数据管理.要维护一个对象关系数据库管理系统长期正常有效地运行,其中一个不可忽略的机制就是数据库的清理机制.PostgreSQL是一个面向公众的、开放源代码的对象关系数据库管理系统,受到了人们的普遍认可和欢迎.对该系统数据清理机制的一个重要组成部分--数据库运行状态的数据统计收集机制进行了全面分析,给出了统计收集信息的种类、主要函数、数据结构和实现算法,这将有助于维护和完善该数据库系统.