Hadoop下负载均衡的频繁项集挖掘算法研究

频繁项集挖掘FIM(Frequent Itemsets Mining)是关联规则挖掘算法的重要组成部分。而经典Apriori和FP-Growth算法在海量数据处理时面临内存占用、计算性能等方面的瓶颈。基于Hadoop云计算平台,提出适用大数据处理的频繁项集挖掘HBFP(High Balanced parallel FP-growth)算法,设计后缀模式转换的数据分割及均衡任务分组方案,使计算节点本地拥有计算所依赖的数据,实现不同节点相互独立的并行数据挖掘方法,并保证算法全局的负载均衡特性。实验数据表明,HBFP算法能均匀地将计算量分散至不同计算节点,并行且相互独立地进行FP-Growth挖掘过程,算法效率提高了约12%,算法全局稳定性及效率取得提升。     

改进FP-Growth算法在旅游线路规划中的应用研究

针对关联规则挖掘的FP-Growth算法存在对海量数据存储时消耗极大内存开销的弊端,提出一种对FP-Growth加入兴趣度的改进算法,然后与Apriori,FP-Growth算法进行比较,改进后的算法极大减少了内存开销,同时提高了系统执行效率。并且提出改进算法与旅游线路规划挖掘结合的理念,以云南旅游业作为旅游规划对象,充分应用旅游网站的大数据,设计一种旅游线路规划的挖掘系统,为旅游企业找出游客最喜欢的旅游线路以及景区之间的关联规则。     

基于FP-Growth的战略绩效关联分析算法研究

在处理战略绩效KPI关联规则挖掘的问题时,由于FP-Growth不能根据业务的需要简化计算过程,从而产生了许多冗余计算,影响了算法的效率。因此,提出了一种基于FP-Growth的战略绩效关联分析算法。通过采用基于规则的约束方法对FP-Growth算法进行改进。一方面,在挖掘的过程中添加剪枝操作,提高频繁项集的挖掘效率;另一方面,在关联规则产生过程中,添加规则约束,生成符合业务要求的关联规则,从而减少了冗余计算,提高了算法的效率。最后,以"某高校科研服务质量指标"为例,验证了该算法的可行性。     

一种基于FUP的TD-FP-Tree并行快速更新算法

TD-FP-Growth是对经典关联规则挖掘算法FP-Growth算法的改进,它采用新的数据结构TD-FP-Tree。人们已经基于Apriori和FP-Growth算法提出了多种关联规则增量挖掘算法。文中讨论了在基于TD-FP-Tree的结构上如何进行增量挖掘,对批量挖掘算法的瓶颈进行分析,指出加快更新速度的策略。文中基于FUP思想提出了TD-FP-Tree的快速更新算法,重点研究了当有单个项在新增事务加入后由非频繁变为频繁时TD-FP-Tree的处理情况。通过将项分类处理降低更新时间,并部分采用并行处理进一步提高效率。实验表明,文中提出的算法不仅可以快速更新TD-FP-Tree,而且在同基于FP-Tree结构的增量挖掘对比中也有更好的表现。     

基于Spark的并行频繁项集挖掘算法

关联规则挖掘是数据挖掘领域的重要研究方向之一。频繁项集的挖掘是关联规则挖掘的第一步,也是最重要的步骤。FP-Growth(Frequent Pattern-Growth)算法因其挖掘效率以及空间复杂度方面的优势被广泛应用于频繁项集挖掘任务中。面对海量数据,FP-Growth算法挖掘效率变得极低甚至失效。在Hadoop大数据平台上实现的基于MapReduce框架的并行FP-Growth算法——PFP算法解决在处理大规模数据时传统算法失效的问题,但是由于其将每次执行之后的中间结果输出到磁盘,降低算法执行效率。为提高并行FP-Growth算法执行效率,提出一种基于Spark的SPFPG算法。该算法运用负载均衡思想对分组策略进行改进,综合考虑分区计算量和FP-Tree规模两个因素,保证每个组之间负载总和近似相等。在Spark上实现FP-Growth算法——SFPG算法的基础上,实现优化后的SPFPG算法。实验结果表明,SPFPG算法相比SFPG算法挖掘效率更高,且算法具有良好的扩展性。     

一种基于MFP树的快速关联规则挖掘算法

在关联规则挖掘FP-Growth算法的基础上,提出一种基于MFP树的快速关联规则挖掘算法。文中给出了MFP算法的工作原理。MFP算法能在一次扫描事务数据库的过程中,把该数据库转换成MFP树,然后对MFP树进行关联规则挖掘。MFP算法比FP-Growth算法减少一次对事务数据的扫描,因此具有较高的时间效率。     

一种基于MFP树的快速关联规则挖掘算法

在关联规则挖掘FP-Growth算法的基础上,提出一种基于MFP树的快速关联规则挖掘算法。文中给出了MFP算法的工作原理。MFP算法能在一次扫描事务数据库的过程中,把该数据库转换成MFP树,然后对MFP树进行关联规则挖掘。MFP算法比FP-Growth算法减少一次对事务数据的扫描,因此具有较高的时间效率。     

基于FP-Growth的智能家居用户时序关联操控习惯挖掘方法

针对传统关联规则挖掘算法无法高效且准确地挖掘出隐含于用户操作记录中的时序关联操控习惯,提出一种基于FP-Growth的智能家居用户时序关联操控习惯挖掘算法。该算法分为三个阶段,分别为基于用户操控动作森林、改进的FP-Growth算法和一种时间约束规则进行事务集的生成、时序频繁项集的生成以及最终时序关联操控习惯的生成。最后,使用真实用户操控记录进行对比实验,结果表明该算法能提高生成事务集的效率,并能更准确地发现用户操控家居设备的时序关联习惯。     

基于局部性原理的分布式关联规则挖掘算法

针对分布式数据挖掘需要节点间进行大量数据交换的缺点,根据张春生,宋琳琳提出的关联规则局部性原理,不进行数据交换,通过节点挖掘,直接得到局部性全局关联规则,通过各节点间规则的合并,直接得到非局部全局关联规则,该算法简单易行,不需要节点间的数据交换,提高了数据挖掘效率,不仅挖掘出其他分布式数据挖掘算法挖掘出的全局关联规则,还能够发现其他算法不能发现的局部全局规则.     

一种面向高校学生体测数据的模式挖掘方法

目前,每年测试高校大学生的体质健康,会产生大量的数据,为了提高关联规则对体测数据的挖掘效率,提出了一种面向高校学生体质测试数据的模式挖掘方法。利用经典的关联规则挖掘方法如Apriori算法和频繁模式树（Frequent Pattern Tree,FP-Growth）算法,对体测数据进行关联规则挖掘。实验结果表明,该模式挖掘的最小数据集能有效提高关联规则算法对体测数据的模式挖掘效率。     

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