改进的Apriori算法在云计算挖掘下的研究

云计算下的数据挖掘一直都是研究的重点,本文以基本的Apriori算法为基础,提出了构建适合云计算下的数据集分解方式,减少扫描数据库次数和减少频繁项集自连接比较次数的三个策略,并从挖掘频繁1项集,2项集和多项集进行描述。仿真实验中将本文算法与基本Apriori算法、改进的Apriori算法进行比较,取得了比较好的效果。     

并行拓展及关联分析的户外运动资源整合模型

为了更好的对户外运动资源进行整合,以提高资源利用率,本文采用数据挖掘技术构建了一种并行拓展及关联分析的户外运动资源整合模型。首先将整个数据集随机分割成若干个非重叠子数据集,并且每个子数据集还可继续划分成更小的子集,进而并行分层地挖掘出局部频繁项集,然后根据频繁项集先验性质,连接局部频繁项集得到全局候选项集;最后扫描数据集统计出每个候选项集的实际支持度,以确定全局频繁项集。算法实例仿真结果表明,本文提出的改进算法与普通Apriori算法相比更高效,并且在户外运动资源整合的应用中,本文提出的算法表现出更好的挖掘效率。     

基于径向基函数神经网络的数据关联挖掘算法设计

为了提高用户需求数据挖掘的时效性及准确性,提出基于径向基函数神经网络的数据关联挖掘算法。在对数据频繁项集约束性关联规则研究的条件下,通过约简计算,得到满足约束条件的候选数据集,并对用户需求数据频繁项集更新;利用径向基函数神经网络对候选数据集进行训练优化,通过上界剪枝法,获取用户需求数据,并实现其实时挖掘。实验结果表明,所提数据挖掘算法执行效率受数据规模变化的影响较小,挖掘效率更高,扩展性更好。     

基于单次扫描无构造调节的频繁模式挖掘算法

研究频繁项集模式挖掘优化问题。传统的挖掘算法常产生大规模的候选项集,并且反复扫描数据库,导致频繁项集挖掘时间过长,空间效率太低。为了改进频繁项集挖掘时时间与空间效率低的问题,提出一种高效频繁项集挖掘算法CPT-Mine。此算法利用编码模式树存储事务数据库中的频繁项集信息,构建FP数组,加快产生频繁项集,引入CPT-Mine算法,快速地挖掘数据库中所包含的频繁项集,无需递归构造条件模式树,只需两次扫描数据库即可生成所有频繁项集。最后的实验证明了该算法能缩短挖掘时间3～10 s,空间效率提高43%。     

大数据下的一种挖掘算法的研究

在大数据背景下进行数据挖掘越来越受到重视,针对Apriori挖掘算法中存在消耗时间长,算法效率低的特点,采用添加数据库、改进频繁1-项集,改进频繁2-项集和引入动态存储空间等措施,提高Apriori算法的性能,仿真实验中,本文算法在时间消耗、CPU耗能和挖掘效果上都取得了良好的效果。     

一种小区域分类关联的高冗余空间挖掘算法

传统的关联规则挖掘技术过于依赖数据之间的关联属性,造成挖掘算法在高冗余知识空间关联规则不明显或者较弱的情况下挖掘耗时。本文提出一种应用与高冗余知识空间的优化数据挖掘算法。该算法首先找出最大频繁项集和频繁1-项集进行区域分类,然后利用已有频繁项集找出所有的其它频繁项集,去除冗余关联环境,节省了计算频繁项集的时间,节约了存储空间,使算法的效率得到提高。仿真实验结果证明了改进算法的可行性和有效性。     

频繁项集挖掘算法研究

在数据库中挖掘频繁项集是数据挖掘领域的最基本、最重要的问题。自从Agrawal的开创性工作以来,有关研究从未停止过。然而由于其内在的计算复杂性,这一问题并未完全解决。通过描述频繁项集挖掘的特点,并根据解空间的分类对已有各种频繁项集、闭频繁项集、最大闭频项集和不生成频繁项集的挖掘算法进行了分析和比较。     

一种利用逻辑"与"运算挖掘频繁项集的算法

在挖掘关联规则的过程中,关键步骤是产生频繁项集。文中利用逻辑与运算并建立频繁项集支持矩阵,提出一种有效的频繁项集挖掘算法—LA。算法利用逻辑与运算挖掘频繁项集,不产生候选项集,且只需扫描数据库一次,所以此算法是非常有效的。     

一种利用逻辑“与”运算挖掘频繁项集的算法

在挖掘关联规则的过程中，关键步骤是产生频繁项集。文中利用逻辑与运算并建立频繁项集支持矩阵，提出一种有效的频繁项集挖掘算法-LA。算法利用逻辑与运算挖掘频繁项集，不产生候选项集，且只需扫描数据库一次，所以此算法是非常有效的。     

基于关系数据库的教学评价数据的关联规则挖掘

频繁项集的挖掘是数据挖掘中的一个十分重要的组成部分。本文结合关系数据库的特殊性,利用标准SQL语言,提出适合于关系型数据库频繁项关联规则挖掘的算法,应用于教学评价数据的挖掘,得出一些潜在的关联信息,为教学管理提供决策。     

Low doses of a red wine ingredient figh diabetes in mice

Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said.     

To serve and promote science development via innovation

CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing.     

Tracing the origin and early radiation of birds——Paleornithologist ZHOU Zhonghe

With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants."     

Students' Reactions to the Introduction of Videoconferencing for Classroom Instruction

This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors.     

Molecular motor assembly of a biomimetic system

Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction.     

Cooler temperatures inductive to locust outbreaks

Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007.     

Exploring Multiplexity: Social Network Structures in a Computer-Supported Distance Learning Class

A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction.     

The Role of Intermediating Institutions in the Diffusion of Electronic Data Interchange (EDI): How Industry Associations Intervened in Denmark, Finland, and Hong Kong

Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies.     

The Information Environment and Universal Service

This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment.     

How Electronic Publishers are Protecting Against Piracy: Doubts About Technical Systems of Protection

The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means.