Probabilistic D-Clustering

We present a new iterative method for probabilistic clustering of data. Given clusters, their centers and the distances of data points from these centers, the probability of cluster membership at any point is assumed inversely proportional to the distance from (the center of) the cluster in question. This assumption is our working principle. The method is a generalization, to several centers, of theWeiszfeld method for solving the Fermat–Weber location problem. At each iteration, the distances (Euclidean, Mahalanobis, etc.) from the cluster centers are computed for all data points, and the centers are updated as convex combinations of these points, with weights determined by the above principle. Computations stop when the centers stop moving.     

Number crunching vs. number theory: computers and FLT,from Kummer to SWAC (1850–1960), and beyond

The present article discusses the computational tools (both conceptual and material) used in various attempts to deal with individual cases of FLT, as well as the changing historical contexts in which these tools were developed and used, and affected research. It also explores the changing conceptions about the role of computations within the overall disciplinary picture of number theory, how they influenced research on the theorem, and the kinds of general insights thus achieved. After an overview of Kummer’s contributions and its immediate influence, I present work that favored intensive computations of particular cases of FLT as a legitimate, fruitful, and worth-pursuing number-theoretical endeavor, and that were part of a coherent and active, but essentially low-profile tradition within nineteenth century number theory. This work was related to table making activity that was encouraged by institutions and individuals whose motivations came mainly from applied mathematics, astronomy, and engineering, and seldom from number theory proper. A main section of the article is devoted to the fruitful collaboration between Harry S. Vandiver and Emma and Dick Lehmer. I show how their early work led to the hesitant introduction of electronic computers for research related with FLT. Their joint work became a milestone for computer-assisted activity in number theory at large.     

基于PVAR模型三峡库区基础设施与经济增长的互动效应

基础设施与经济增长具有动态互促互进的理论关联,但对于外部援助下的贫困地区发展而言,二者关系具有现实特殊性;三峡库区既有历史贫困特征,又受到外部援助资金的大力支持,运用面板向量自回归模型对库区15个区县2000—2018年的基础设施和经济增长进行了实证分析;研究结果发现:三峡库区基础设施对经济增长具有动态促进作用,反之则不显著,二者具有单向互动关系,在脉冲响应分析中,二者互动效应呈现"倒U型"特征,时滞效应呈现"反J型"特征;现阶段,三峡库区基础设施与经济增长互动效应还不明显,在一系列帮扶政策收官期限之前,建议从两方面来增强基础设施与经济增长的内生互动,一是要明确各类帮扶政策分类分阶段有序退出的时间表,二是以区县为主体共建三峡库区基础设施发展基金。     

一类非线性自治大系统的全局稳定性

本文研究非线性自治大系统 dx_i/dt=sum from i=1 to r(f_(ij)(x_j)) (i=1,…,r) 这里,x_i∈R~(ni),f_(ij)∈C(R~(nj),R~(ni),f_(ij)(o)=0,得到保证其零解为全局一致渐近稳定的充分条件(见定理1)。     

AUTOMATIC DECISION-MAKING： NEURAL FIRING AND RESPONSE

1. Introduction This is the fourth exposition on theAnalytic Hierarchy Process. It is true thatmany decisions we make subconsciously ariseout of our physical and biological needs andderive from the pressure to survive physically.We also make subconsciou…     

MAN-MACHINE COLLABORATED KNOWLEDGE CREATION IN HWMSE

1 Introduction Science of complexity and complex systems is a relatively new area In wide fields from chemistry, biology, environment, geo-science, climatology to economics and sociology, complexity has been studied from diverse views and understandings Systems science, which could be traced back to Ludwig von Bertalanffy’foundational work on general system theory, plays an active role in complexity studies From system perspectives, relevant concepts often include interaction, feedback, evol…     

焊缝熔透检测及控制的国内外发展概况

介绍了国内外关于焊缝熔透自动控制的发展概况，对各类焊缝熔透控制方法进行了分析，为了解焊缝熔透自动控制提供了一定的参考价值．     

梯度投影法在测量平差中的应用

本文以梯度投影法迭代直接求解出观测值的改正数,并在最后给出一个简单算例,以资验证。     

极大子群的指数复合与有限群的可解性

建立了以有限群的极大子群的指数复合刻划可解性的两个新定理。     

Preparation and characteristics of flexible all-organic thin-film field-effect transistor

Much attention has been attracted to organic thin-film field-effect transistors (OTFFETs) in the past decades[1—4]. Because of their lower cost and easier preparation, OTFFETs are considered to be useful in driving liquid crystal displays (LCD) and organic light-emitting diodes (OLED). Furthermore, flexible OTFFETs will be one of the most useful electronic devices for flexible active matrix driving circuits. OTFFETs based on pentacene single crystal have been reported to be of g…