一种新的求解Min-Max问题的逼近算法

针对极大极小(Min-Max)问题中极大值函数的不可微性,构造了一种针对极大值函数新的光滑逼近函数,并讨论了该逼近函数的若干性质,给出一种求解极大极小问题的具有大范围收敛性的算法,数值结果表明算法是有效的.     

随机连续系统基于Laguerre多项式逼近的Markov参数估计

先讨论基于Ｌａｇｕｅｒｒｅ多项式逼近、有连续Ｗｉｅｎｅｒ过程扰动的随机连续线性系统最小二乘参数估计，然后讨论Ｗｉｅｎｅｒ过程的Ｌａｇｕｅｒｒｅ多项式逼近值的相关性和最小二乘估计的有偏性，在此基础上，提出无偏一致的Ｍａｒｋｏｖ估计（最小方差估计）算法，仿真结果显示本文方法的有效性．     

一种基于DE-SVR的逼近算法及其在CPI预测中的应用

利用逐级逼近思想建立起一种基于DE-SVR的逼近算法.通过运用该算法对居民消费价格指数(CPI)进行预测的实验证实,该算法有着很高的预测精度,是一种进行回归拟合的新算法.     

一个关于MAC伪随机性与不可伪造性的注记

文献[1]证明了XOR-MAC的伪随机性,即XOR-MAC的标签生成算法和随机函数不可区分,进而宣称给出了XOR-MAC的安全性新证明.本文通过对Wegman-Carter MAC的研究, 说明了随机的或者带状态的MAC的伪随机性并不意味着MAC的安全性,即不可伪造性.     

基于离散余弦变换和支持向量机的数字图像水印算法

为了加强数字图像版权保护,提出一种基于离散余弦变换(DCT)和支持向量机(SVM)的数字图像水印算法.该算法首先充分利用SVM很强的非线性逼近能力,计算水印的嵌入强度,然后将水印自适应地嵌入到DCT变换各系数中,从而解决水印嵌入强度和DCT系数的选择难题.实验结果表明,该算法不仅具有水印具有不可感知性,而且抗各种攻击能力强.     

基于数值方法的龙格函数分析

通过使用不同的数值插值算法和函数逼近方法对提出的龙格函数进行分析总结,得出在对应不同类型的算法时,龙格函数是否显出病态性,插值方法是否对于高阶的问题仍然适用的相关结论.对拉格朗日插值、牛顿插值、切比雪夫多项式零点插值、三次样条插值、曲线拟合等数值算法通过具体的Matlab程序,做出他们的相应的函数图形并进行结果分析,以得出每个数值方法的性质,适用范围和优缺点.     

中国PPP项目可融资性差吗?——基于集成LightGBM-Blending算法

可融资性是PPP可持续发展的前提和基础.针对PPP项目可融资性存在行业差异性高及评价类别型字段过多问题,为防止评估过程出现严重过拟合现象和因二次加工产生的误差,提出集成LightGBM-Blending算法.基于社会资本视角构建可融资性评估体系,借鉴集成思想按行业划分训练集,构建以LightGBM算法为基础的多基分类器...     

基于遗传算法的数字曲线多边形逼近的实现

平面曲线的多边形逼近是模式识别和计算机舰觉研究中的常用算法,为克服顶点的检测只依靠局部区域、缺乏全局信息的弱点。提出了一种利用遗传算法的最优多边形逼近算法。     

基于随机微分方程的易逝性高科技产品更新时机研究

基于易逝性高科技产品的价值易逝性与高新技术特性，构建基于随机微分方程的易逝性高科技产品更新时机模型以解决易逝性高科技产品更新时机不确定性问题。首先，利用威布尔分布和多项式逼近函数构造无技术进步与价值易逝等外部因素干扰的易逝性高科技产品使用寿命模型；其次，采用布朗运动来模拟外部因素对易逝性高科技产品更新时机的影响情况，进而建立技术进步和价值易逝影响下易逝性高科技产品更新时机波动率模型；最后，选取i Pad作为易逝性高科技产品案例验证所构建的易逝性高科技产品更新时机模型，研究结果表明该模型具有较强的稳健性，可为高新技术生产企业在产品更新换代时提供一定的参考。     

新院士主要科技成就(十一) 我在随机系统研究中的工作成绩

我1961年毕业于列宁格勒大学数学力学系,30多年来一直研究控制理论.主要工作分四方面.一、状态估计和随机控制.能观性和能控性是控制理论中的基本概念.我对随机系统给出了随机能观性和能控性的新定义,揭示了系统这种属性的本质,并用这证明了不用初始条件的各种状态估计的联系,为工程中常用的方法提供了理论依据.对二次指标下的     

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.     

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.     

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."     

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.     

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.     

Rough Justice: A Statistical Assessment of ICANN's Uniform Dispute Resolution Policy

Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP.     

Prevalence of soft neurological signs in Chinese people

Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.     

Stern-Gerlach effect goes chiral

Prof. SUN Changpu from the CAS Institute of Theoretical Physics and coworkers from University of Basel in Switzerland have worked out a way --at least in theory --to split a beam of molecules according to their chirality. The technique involves passing the molecules through three different laser beams and is similar to the famous Stern-Gerlach effect, whereby a beam of atoms passing through a magnetic field is split in two according to the atoms＇ spin states （Phys. Rev. Lett. 99 130403）.