偏微分方程平衡解的稳定性分析

偏微分方程的平衡解稳定性分析在线性系统控制性能方面具有较好的应用性。通过研究偏微分方程的初值和稳定性问题,基于非线性动力系统在Cauchy核中的时滞性,进行偏微分方程的自适应李雅普诺夫指数泛函,对方程进行初值的二阶泰勒级数展开,采用共轭梯度法对偏微分方程求解平衡解,对平衡解进行边界条件分析,通过求解平衡解边界值,进行偏微分方程的平衡解稳定性证明。数学理论推导得出,该类偏微分方程的平衡解渐进稳定的,结论为稳定性控制提供理论基础。     

重积分微分方程重叠型稳定解估计算法

结合重积分微分方程的稳定性理论,得知重积分微分方程中多复变微分方程的初值解不一定可逆,使用近似矩阵进行渐进逼近,根据自相关函数信息矢量迭代模型,得到当自相关向量的最小互信息量达到渐进稳定,求解双边界条件下的稳定性平衡点,实现全局渐进稳定,在重积分微分方程中对多复变微分方程进行时空分叉问题的分析和初值解的稳定性和收敛性分析,通过数学推导和数值分析,得出重积分微分方程重叠型稳定解存在,且具有收敛性。     

一类随机泛函微分方程的边值问题收敛性分析

随机泛函微分方程模型对大规模海量数据集的处理和训练上,有其独特的优势,解决随机泛函微分方程的边值问题,并进行收敛性分析,具有重要的意义。通过数学推导证明了半正定最小正特征带状稀疏条件下的稳定特性,对随机泛函的连续边值就行稳定误差逼近分析,采用共轭梯度法进行奇异分解,将边值收敛条件代入随机泛函椭圆函数,得到一个自回归线性最优解集,根据多目标优化理论,构建随机泛函微分方程扰动夹逼定理,根据复值函数凸组合优化定理,给定刚度矩阵小的半正定最小特征,求得该类随机泛函微分方程的边值凸组合模型渐进收敛条件。研究理论将在位移逼近和稳定性控制等领域具有较好的应用价值。     

Bochner-Riesz空间估计生成的对称复矩阵稳定解

采用Bochner-Riesz矩阵构造对称复矩阵,根据极大熵准则,利用强度离散性微分边界方程不稳定的边界平衡点,动态描述Bochner-Riesz空间中多复变微分方程的线性初值解,用一种鲁棒非平衡的ELM方法,求解一类由Bochner-Riesz空间估计生成的对称复矩阵稳定解,提高系统的稳定性能。     

无穷维Bernoulli空间中微分方程的连续逆平稳解

无穷维Bernoulli空间中的微分方程连续逆平稳解是实现对特征灵敏的二阶模糊逻辑系统稳定性控制的关键理论基础。在二阶模糊逻辑控制系统中,讨论无穷维Bernoulli空间中微分方程和(2+1)维GIR方程的波动结构平衡点变化特点。采用变尺度思想,将广义梯度投影算法引入道无穷维Ber-noulli空间中微分方程的连续逆平稳解求解过程中,并推广到带线性不等式约束优化问题上。结合特征函数在渐进性条件下的Lyapunov-Krasovskii泛函算法,对无穷维Bernoulli空间中微分方程的渐进性条件临界阈值确定,以有效分析微分方程的稳定解存在性,研究分析得到在一类时间尺度上无穷维Bernoulli空间中的微分方程调控函数式具有连续逆平稳解的,进行指导模糊推理控制系统获得最优的控制品质。     

有限Morrey空间内一类离散时滞系统的周期解唯一性分析

分析有限Morrey空间内离散时滞系统周期解唯一性问题,为该类离散时滞系统控制的稳定性和收敛性提供理论基础。采用微分方程求解和Lyapunove泛函方法进行系统模型构建和特征解求取,构建五次波动微分方程,结合Lyapunov泛函进行有限Morrey空间内离散时滞系统的稳定性分析,在能量超临界情况下,构建有限Morrey空间内一类离散时滞系统的Terminal滑模面,得到在有限时间域内系统具有稳定周期解唯一性条件,进行了周期解的存在性、唯一性和渐进收敛性的判决分析和推导证明,为时滞控制提供理论基础。     

Fouerier变换法求解弦振动方程Cauchy问题

本文探讨了主要利用Fourier变换法求解弦振动方程Cauchy问题。首先,利用Fourier变换的定义及性质把要求解的偏微分方程转化成常微分方程。然后,利用常微分方程的基本方法求解出常微分方程的解。最后再取逆变换,用三种方法通过Fourier的性质得到原定解问题的解,改变了以往的用行波法推导弦振动方程Cauchy问题的达朗贝尔公式的方法。     

分数阶广义积分-微分方程Riesz基的置信域估计

分数阶广义积分-微分方程Riesz基的置信域估计关系到方程是否存在稳定解,由分数阶广义积分-微分方程的初值解构成Riesz基,采用广义最小二乘估计(GLS)方法构成Riesz基的回归参数的置信域,广义积分-微分方程局部解存在性根据广义特征函数的分数阶非线性增长性约束条件进行验证。在重特征值的根子空间中通过Lyapunov泛函分析分数阶广义积分-微分方程Riesz基的置信域,通过计算最小二乘估计(OLS)估计的经验覆盖概率提高置信域估计的精度。     

拟线性微分方程边值解的稳定性及收敛性分析

拟线性微分方程边值解的稳定性问题以及收敛性问题是进行时滞系统稳定性控制的关键因素,分析该类微分方程边值解的稳定性及收敛性,首先通过计算微分方程的连续逆平稳的二阶梯度,构建微分方程的连续逆平稳约束模型;其次引入微分方程的逆特征值有稳定解的边界条件,采用时滞关联度特征泛函进行拟线性微分方程的特征解空间遍历,求得具有的拟线性微分方程的边值解;在此基础之上,进行了边值的稳定性和渐进收敛性分析。研究得出,该类微分方程存在边值周期解,在时滞系统控制中具有较好的收敛性。     

线性模型中二阶微分方程的超稳定振动性定理

分析线性模型中二阶微分方程的超稳定振动性,为解决系统的稳定性控制问题提供数学理论基础。对线性模型中二阶微分方程的超稳定性进行幅相裕度优化控制研究,构建二阶微分方程,采用向量Lyapunov函数方法进行了时滞相关特征分解,在异变平衡点分解中采用幅相裕度优化控制方法对微分系统的时滞参数进行稳定性分析,得到了线性模型中二阶微分方程超稳定解,给出了超稳定振动性定理,数学分析得出,线性模型中的二阶微分方程具有超稳定振动性特征,给出的超稳定振动性定理可靠,微分方程的特征解是稳定收敛的,以此指导稳定性控制,提高控制精度和可靠性。     

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.     

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.     

Monoculture Rubber Plantations Have Negative Ef ects on Controlling Splash Erosion

<正>In Xishuangbanna,one of China’s most biodiverse regions,landscape has changed dramatically during the past three decades due to the conversion of tropical rainforest to rubber plantations.In steep areas,terraces are often constructed before planting rubber trees,which causes two important changes in the soil:the destabilization of soil in the bench terraces and the increased vulnerability of unvegetated riser faces to erosion.Few studies have documented the nature and intensity of erosion on bench terraces.Prof.LIU Wenjie and his colleagues from the Xishuangbanna Tropical Botanical Garden(XTBG)conducted a study in Menglun County(21°5′39″N,101°15′55″E),Xishuangbanna to evaluate the influence     

Chinese Scientists Use Earth Observation Technologies to Study and Protect Wild Camels

<正>Chinese scientists plan to apply Earth Observation technologies to protect the critically endangered wild camels(Camelus ferus).With the help of remote sensing,satellite positioning,geographical information system and wireless sensors networks,they will be able to access the distribution and population of the wild camels and protect their habitats.The project will be carried out by the International Research Center for Wild Camel Conservation,which was jointly established earlier this year by the Institute of Remote Sensing and Digital Earth(RADI)of the Chinese     

More than Skin Deep – Understand Skin Biology by Means of Dermatogenomics

<正>The Paul Gerson Unna Research Group on Dermatogenomics was founded in October 2012 at the Partner Institute for Computational Biology.The ultimate goal of the group is to understand the biology of skin and skin appendages.