语义Web中RDF元数据的存储与管理

语义Web的实现首要解决的问题就是对资源的描述,RDF是描述信息资源的基础,管理和存储RDF数据成为必须要解决的问题。如果把RDF数据存储在关系数据库中,就可以有效地利用现有的数据库资源来管理RDF数据。本文用垂直Scheme的格式来构造RDF数据存储表,通过模式映射把RDF数据映射成RDF数据存储表中的记录;此外又给出了用RDF视图查询RDF数据的方法为实现语义查询打下了基础。     

NoSQL数据管理技术

社交网络和微博等新型应用对数据管理技术提出了新的挑战,如海量数据高效存储、高并发访问、高可扩展性和高可用性等。而传统的关系数据库技术无法满足这些新型应用的需求,因此,NoSQL数据管理技术的研究、开发和应用越来越受到重视。本文从NoSQL数据模型、数据存储、查询处理以及SQL与NoSQL混合数据库解决方案等方面,综述了NoSQL数据管理技术发展现状和趋势,并介绍了几种典型的NoSQL产品。     

NoSQL数据库系统

大数据的出现与不断发展促进了NoSQL数据库技术的发展及其产品应用,为大数据的存储、传输与处理创造了生态环境。文章介绍NoSQL数据库的产生过程、特点与潜力、存储方式与分类以及目前常用的NoSQL数据库系统。     

大数据中RDF语义数据存储优化探讨

结合大数据的特点和语义Web的理论,对大数据中的RDF语义数据的描述和存储进行研究。分析各种数据库存储RDF语义数据的优点和缺点,指出图数据库存储RDF语义数据的优势。最后采用Neo4j开源Java代码实现了一个图数据库系统,通过运行实例验证了以上结论。     

基于Neo4j的领域本体存储方法研究*

在分析民航突发事件应急管理领域本体及其存储特点的基础上,提出了一种基于Neo4j的领域本体RDF图数据存储方法,研究了领域本体RDF有向标记图结构与Neo4j图数据库存储模型的关系,结合民航突发事件应急管理领域本体的实例查询,给出了RDF图与Neo4j之间的映射关系及其实现过程。实验验证了Neo4j图数据库在满足领域本体RDF图数据查询的同时,进一步提高了查询的效率,为大数据平台下的RDF图数据语义检索与推理提供了方法支撑。     

基于列数据库的RDF数据管理实现

随着语义网的发展,Web上越来越多的开放数据以RDF格式发布,对海量RDF的有效管理是实现语义网的一个重要条件.文中讨论并分析了现有的几种RDF数据存储方法,针对垂直划分的方法,基于列数据库MonetDB,实现了一个RDF数据管理方案.该方案将RDF和RDFS信息分开存储,并在Barton数据集上,设计了包含几种连接的基准查询,对比RDF管理系统Sesame的三元组模式,分别进行了存储空间和查询效率测试.实验结果验证了基于列数据库的垂直划分方案的有效性.     

基于文档数据库的NoSQL建模方法

电子商务、大型社交网站的出现对数据存储、查询和管理带来了新的挑战,也引起了非结构化的面向信息的数据爆炸,海量数据的存储对信息的查询和管理提出了更高的要求。而传统的关系数据技术在应对超大规模和高并发的数据处理方面已经显得力不从心,NoSQL作为一种针对大规模数据应用的新型数据库技术,越来越受到重视。本文以NoSQL数据模型的基础,介绍文档型数据库建模的方法。     

基于分布式NoSQL数据库的档案大数据存储与检索方案研究

随着数字档案资源体系建设的不断加快,档案数据的种类日趋丰富,数量迅猛增长,呈现出大数据的特征。传统关系型数据库与集中式存储在档案大数据处理方面存在着适应性、可靠性和扩展性不足的问题。针对当前遇到的问题,通过分析传统档案数据存储模式的局限性,将分布式NoSQL数据库、分布式文件系统、分布式搜索引擎应用于档案大数据的管理。设计一套基于分布式NoSQL数据库的档案大数据存储与检索方案,并开发原型系统进行验证。     

基于图数据库的RDF数据分布式存储

RDF数据模型具有天然的图结构,因此以图结构存储可以避免RDF逻辑数据模型到物理数据模型的转换。基于图数据库的RDF数据分布式存储方案,重点讨论RDF图数据流分割、图数据库分布式扩展、SPARQL查询语言转CYPHER图形查询语言等。实验对比了基于Neo4j图数据库与基于MySQL关系型数据库的RDF数据存储方案的处理性能,并验证了RDF图数据流分割算法的有效性。     

基于分布式的RDF数据分割方法研究

基于分布式的RDF数据分割方法能够解决大规模RDF数据的分割和存储问题。为保证RDF数据的分布式存储和解决数据分割效率提出了一种基于贪婪策略的分割方法。先通过启发式贪心策略根据子图的负载均衡，依次选择度数最高的节点或者度数相对较高的节点，将其放入同一个子图中，后进行相邻顶点的优化。然后通过分区策略将子图分配到对应节点，存储到neo4j数据库并建立相应的索引将数据保存到Redis数据库。实验对比了几种数据分割算法以及图形数据库与关系型数据库的RDF数据存储方案，并验证了RDF图数据的存储方案和分割算法的有效性。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate