On the geometry of the smallest circle enclosing a finite set of points

A number of numerical codes have been written for the problem of finding the circle of smallest radius in the Euclidean plane that encloses a finite set P of points, but these do not give much insight into the geometry of this circle. We investigate geometric properties of the minimal circle that may be useful in the theoretical analysis of applications. We show that a circle C enclosing P is minimal if and only if it is rigid in the sense that it cannot be translated while still enclosing P. We show that the center of the minimal circle is in the convex hull of P. We use this rigidity result and an analysis of the case of three points to find sharp estimates on the diameter of the minimal circle in terms of the diameter of P.     

Unsupervised word sense disambiguation for Korean through the acyclic weighted digraph using corpus and dictionary

Word sense disambiguation (WSD) is meant to assign the most appropriate sense to a polysemous word according to its context. We present a method for automatic WSD using only two resources: a raw text corpus and a machine-readable dictionary (MRD). The system learns the similarity matrix between word pairs from the unlabeled corpus, and it uses the vector representations of sense definitions from MRD, which are derived based on the similarity matrix. In order to disambiguate all occurrences of polysemous words in a sentence, the system separately constructs the acyclic weighted digraph (AWD) for every occurrence of polysemous words in a sentence. The AWD is structured based on consideration of the senses of context words which occur with a target word in a sentence. After building the AWD per each polysemous word, we can search the optimal path of the AWD using the Viterbi algorithm. We assign the most appropriate sense to the target word in sentences with the sense on the optimal path in the AWD. By experiments, our system shows 76.4% accuracy for the semantically ambiguous Korean words.     

Optimization of some factors affecting the performance of query expansion

This paper examines the factors affecting the performance of global query expansion based on term co-occurrence data and suggests a way to maximize the retrieval effectiveness. Major parameters to be optimized through experiments are term similarity measure and the weighting scheme of additional terms. The evaluation of four similarity measures tested in query expansion reveal that mutual information and Yule's Y, which emphasize low frequency terms, achieve better performance than cosine and Jaccard coefficients that have the reverse tendency. In the evaluation of three weighting schemes, similarity weight performs well only with short queries, whereas fixed weights of approximately 0.5 and similarity rank weights were effective with queries of any length. Furthermore, the optimal similarity rank weight achieving the best overall performance seems to be the least affected by test collections and the number of additional terms. For the efficiency of retrieval, the number of additional terms needs not exceed 70 in our test collections, but the optimal number may vary according to the characteristics of the similarity measure employed.     

复杂性科学与现代城市管理

随着城市人口和规模的扩大,城市的结构、层次越来越复杂。城市的复杂性决定了城市管理工作的复杂性和艰巨性,它体现在问题的动态性以及城市管理各职能部门之间的相互影响和互动。本文介绍了复杂性科学,特别是开放的复杂巨系统理论及其方法论,在对现代城市及城市管理的复杂性分析基础上,提出现代城市及其管理是一类开放的复杂巨系统,应以复杂巨系统理论来指导城市管理工作,并分析了复杂性科学在城市管理中的应用,对现代城市管理有理论价值和现实意义。     

国家治理信息机制的要素分析

文章认为信息机制不仅具有国家治理体系的属性,而且属于国家治理能力范畴,信息机制不仅是一种信息管理的制度安排,也是政府信息能力的体现。文章提出了价值观念、制度安排、组织实体和信息工具的信息机制四要素分析框架,阐述了信息机制四要素的内涵及相互关系,提出了在开放科学的理念引领下,构建信息、资源和处置权相配套的制度体系,加强多元协同的政策共同体建设,增强信息工具的公共物品属性,四要素综合协调,多维度发力的完善国家治理信息机制路径。     

"单片机技术"实践教学改革的思考

在深入分析了就业市场和有关的职业岗位技能的需求以及单片机技术教学特点的基础上,结合本课程的特点,特别是实践教学的经验及不足,对职业院校单片机实践教学进行了探讨,提出了单片机实践教学改革的主要思路和具体措施,并对课程的发展前景进行了分析.     

科学发展观教育理论的时代蕴涵

科学发展观教育理论是以科学发展观为指导,在全面和深刻总结改革开放以来我国教育事业发展经验的基础上形成的面向现代化、面向世界、面向未来的教育理论。科学发展观教育理论丰富了马克思主义教育理论,是中国特色社会主义教育理论的重要组成部分;体现了中国特色社会主义教育事业发展的内在逻辑与必然要求,开辟了马克思主义教育理论在中国发展的新境界;概括了中国特色社会主义教育事业发展的基本特征和总体要求,体现了鲜明的时代性和科学性。     

医学机能学实验室标准化管理的实践与探索

机能实验室标准化管理是一项长期而艰巨的任务,结合机能实验室几年的标准化管理的实践进行探讨,阐述实验室岗位责任制实施的体会,并提出了一些关于实验室标准化管理的方法,探索医学机能学实验室管理的新模式.     

文与道争鸣中宋代之文学宋玉批评与理学宋玉批评

宋代的宋玉批评。是在文与道争鸣的文化背景中进行的。当时,人们为了阐述自己的文道观。常常以屈原及其后学宋玉为例论证各自的主张。于是他们有关宋玉的批评就在文与道的争鸣中展开了。考察宋代的宋玉批评。绝大多数批评家对于战国末年的辞赋家宋玉与其作品给予了充分的肯定,只有极少数理学家持否定态度。这有力地说明。肯定宋玉的文学史地位。肯定宋玉作品的讽谏内容和创作艺术,不仅是宋代宋玉批评的主流。而且有着超大比例的强势。     

圆形镜平面腔数值迭代计算

从菲涅尔-基尔霍夫积分衍射方程出发,推导了圆形镜平面腔所满足的自再现模迭代方程,给出了数值迭代方程的具体形式和TEM00、TEM01、TEM10 3个模式的具体迭代方法。分析计算了3个自再现模的形成过程、单程损耗及相位等特性,并比较了不同菲涅尔数时各模式的本征值和衍射损耗。该方法为研究圆形平面镜谐振腔的激光模式、损耗特性及相位提供了可靠的理论方法,具体的数值迭代方法也可推广应用到其他类型的谐振腔。