基于PCA改进的SOR-LS-SVM公路旅游客流量预测模型

影响公路交通旅游客流量的众多因素增加了预测模型中的输入变量复杂性,减少了模型运行速度和预测准确度。首先,采用主成分分析法对影响公路旅游客流量的指标进行分析得到了主成分即输入变量,然后建立以主成分为输入变量、以旅游客流量为输出变量的基于超松弛改进的最小二乘支持向量机预测模型。通过实际例子验证和比较,揭示了基于主成分分析法改进的超松弛的最小二乘支持向量机公路交通旅游客流量预测模型具有较好的预测精度和较高的应用前景。     

基于PCA改进的SOR-LS-SVM旅游流量预测模型

利用主成分分析法建立以主成分为输入变量而以入境旅游客流量为输出变量的超松弛最小二乘支持向量机预测模型.通过实例验证和比较,演示了基于主成分分析改进的超松弛最小二乘支持向量机入境旅游客流量预测模型有较好的预测效果和较高的推广价值.     

基于PCA-SOR-LS-SVM模型的入境游客流量预测研究

入境旅游客流量预测模型中输入变量的多少在一定程度上制约了模型的模拟速度和预测效果。首先,由主成分分析法对影响入境游客流量的指标进行综合分析从而确定出少数几个主要指标作为预测模型的输入变量,然后建立以主要指标为输入变量以客流量为输出变量的基于超松弛改进的最小二乘支持向量机预测模型。通过实验仿真,结果显示了基于PCA-SOR-LS-SVM的入境游客流量预测模型具有较好的预测精度和较强的推广价值。     

基于PCA改进的LS-SVM入境旅游客流量预测模型

影响入境旅游客流量的众多因素加大了预测模型输入变量的复杂化,限制了模型的运行速度和预测精确。首先,利用主成分分析对影响入境旅游客流量的众多指标进行综合分析得到主成分,然后建立以主成分为输入变量以入境旅游客流量为输出变量的最小二乘支持向量机预测模型。通过实例验证和比较,展示了基于主成分分析改进的最小二乘支持向量机入境旅游客流量预测模型具有较好的预测效果和较高的推广价值。     

基于LS-SVM的大理州入境游客流量组合预测模型

大理州入境旅游客流量的持续增长引起了大理州政府和旅游业界的高度关注。而对未来入境旅游客流量及时准确的预测成为制定旅游规划的重要依据。依据大理州历年游客流量的数据,提出了基于线性回归、算术移动平均、指数平滑和灰色系统等方法的最小二乘支持向量机大理州入境旅客流量组合预测模型。通过实验仿真,表明该模型具有较高的预测精度,为大理州入境游客流量预测提供了新的方法。     

基于最小二乘支持向量机的非线性广义预测控制

为了解决目前常用的非线性预测模型算法中过学习、存在局部极小值等不易解决的问题,本文提出一种基于最小二乘支持向量机对非线性过程建模并用广义预测控制进行在线滚动控制的算法。仿真结果表明,该控制算法具有很好的控制性能。     

基于混沌优化的支持向量机地下水位动态预测

地下水位动态受到自然因素和人为因素的影响,随机性明显,因此在地下水物理过程分析的基础上构建地下水位动态预测的随机性模型对地下水资源评价具有重要意义。本文将小样本机器学习理论——统计学习理论中的支持向量机理论引入地下水位动态预测。最小二乘支持向量机是支持向量机的一种,考虑到地下水位动态序列的长度和峰值突变性的特点,本文提出一种改进的支持向量机-峰值识别最小二乘支持向量机;并针对支持向量机算法存在的参数优化、训练和测试速度等问题,结合混沌优化方法,建立了基于混沌优化的峰值识别最小二乘支持向量机地下水位动态预测模型;最后本文以内蒙古河套灌区义长灌域1990年~2004年3个灌期(夏灌(4月~6月)、秋灌(7月~9月)和秋浇(10月~11月)降水量、平均气温、蒸发量、引水量、地下水开采量、地下水排泄量和地下水位埋深共15年45个样本资料为数据源,将该模型和原最小二乘支持向量机模型分别用于义长灌域地下水位动态预测。结果表明,该模型的拟合值、检验值和预测值与实际值复合的很好,拟合的平均相对误差绝对值为2.0868%,检验的平均相对误差绝对值为3.4777%,预测的平均相对误差绝对值为6.8589%,且训练和测试速度快,而原最小二乘支持向量机模型预测的平均相对误差绝对值为20.6767%。因此,该模型用于地下水位动态预测是可行和有效的。     

基于混沌搜索的LS-SVM预测算法

为利用最小二乘支持向量机(LS-SVM)来进行预测,首先要确定影响LS-SVM模型的两个主要参数γ和σ,针对该问题提出了采用混沌搜索算法来搜索该模型的最优参数组合。混沌搜索的运动轨迹具有遍历性,随机性,可以进行全局和局部寻优,利用该算法搜索最优参数来确定预测模型,然后将该预测模型用于预测实践。实验结果表明,该模型具有较精确的预测精度和适用性。     

基于最小二乘支持向量机的数据挖掘应用研究

随着数据仓库技术、联机分析技术的发展。基于数据库的数据挖掘已成为一种重要的数据处理手段。最小二乘支持向量机作为一种新的机器学习方法。具有全局收敛性和良好的泛化能力。本文将其应用于数据挖掘的分类与预测研究。通过棱函数的选择及参数优化，并结合支持向量机、多层感知器神经网络模型及判别分析方法进行比较研究，证明最小二乘支持向量机作为一种有效的数据挖掘算法具有较高精度。     

PSO-LSSVM的电力负荷预测研究

对影响电力负荷因素之间的非线性,有效提高电力负荷的预测精度,本文提出了一种最小二乘支持向量机(LSSVM)和粒子群优化技术(PSO)相结合的电力负荷预测方法。以历史负荷数据气象因素等作为输入,建立预测模型,对未来时刻电力负荷进行预测。该模型利用结构风险最小化原则代替传统的经验风险最小化,以充分挖掘原始数据的信息,并采用粒子群优化算法来优化最小二乘支持向量机的参数,旨在提高预测模型的训练预测精度。实际算例表明,使用PSO-LSSVM方法进行电力负荷预测,具有良好的可行性和有效性,与BP神经网络和LSSVM方法的预测结果相比,所提出的PSO-LSSVM模型预测平均误差仅为0.85%,具有更高的精度,适用于电力负荷预测。     

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.     

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.     

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.     

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.     

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."     

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.