Intersections of two offset parametric surfaces based on topology analysis

Conventional methods for solving intersections between two offset parametric surfaces often include iteratively using computationally expensive SSI (surface/surface intersections) algorithm. In addition, these methods ignore the relations between the intersection curves of parametric surfaces with different offset distances. The algorithm presented in this paper, makes full use of the topological relations between different intersection loops and calculates intersection loops with the help of previously calculated intersection loops. It first pre-processes two parametric surfaces to obtain the characteristic points, called topology transition points (TTPs), which can help in the subsequent finding of the topologies of the intersection curves. Then these points are categorized into several distinct groups, and we can determine the calculation strategy for searching initial points by analyzing the properties of these TTPs on the surfaces. Hence, all intersection curves can be marched from initial points by the tracing algorithm. The proposed algorithm could calculate intersection curves robustly and effectively, and has been tested to be capable of overcoming the degenerate conditions such as loop and singularities leaking that occur frequently in conventional algorithms. Project supported by the National Research Foundation for the Doctoral Program (No. 2000033554) of Higher Education of China and the Natural Science Foundation of Zhejiang Province, China (No. 6001107)     

不同覆盖层次的温、光变化及对几种蔬菜生长的影响

对春季不同覆盖层次下温度、植株干重的测定表明:不同覆盖层次下温度变化由高到低依次为:三层覆盖＞二层+草＞二层覆盖＞一层覆盖;光照强度强弱的变化为一层覆盖＞二层覆盖＞二层+草＞三层覆盖;随着覆盖层次的不断增加,植株高度不断增加,茎粗不断减小;植株干重的变化为在苗生长初期以二层覆盖和二层+草覆盖方式下最大,后期则以一层覆盖的植株干重最大;在叶绿素方面,蔬菜种类不同,其变化呈现各自不同的规律.     

英语教学中培养学生自主学习能力探研

提高学生的自主学习能力,不仅能够激发学生进一步学习和探究英语知识的兴趣,而且能够提高学生的英语学习效率。教师要用问题作为课前引导,激发学生的探究兴趣;组织相关实践活动,引导学生主动参加;采用新颖的教学方式,提高学生自主学习效率。     

基于GIS的城市规划方法——以镇江西津渡地区保护与整治为例

以地理信息系统（GIS）技术的5个主要组成部分，即硬件、软件、数据、使用及使用方法为内容，简要介绍了该技术的基本原理及其在城市规划中的应用。着重讨论了在历史遗产保护规划中使用ArcView GIS软件的可行性，并以镇江西津渡历史街区保护规划为例，分析了编制基于GIS技术的规划管理系统时所采用的具体方法。     

中国土地价格形成分析

土地价格是土地市场形成的关键，也是土地经济学理论研究的重要范畴。分析我国土地价格的形成机制应从土地市场、土地价值、土地立法和农村产业结构等几个方面入手。     

论经济全球化下民族文化的融通与发展

民族文化的发展历程伴随与异文化的融汇过程。在经济全球化下 ,中国民族文化与异文化的融通就是建立在社会存在状况趋同基础上的文化之间的竞争、交流与相互扬弃 ;我国民族文化与异文化的融通不仅不会影响其独立的发展 ,反而会带来其新的生机与活力。     

Science Content Courses: Workshop in Food Chemistry for 4th Grade School Teachers

ABSTRACT: A science content course in food chemistry was offered as a 4-day summer workshop from 1999 to 2001 to 4th grade school teachers in the Seattle School District. The objectives of the workshop were to increase the teachers' knowledge of food science, to perform simple experiments that could be used in the 4th grade classroom, and to help the teachers become more familiar with the scientific method. The workshop is described, and challenges associated with running the workshop from the instructors' perspective are discussed. Protocol for hands-on experiments used in the workshop, discussion questions/answers, and comments about each experiment are included in Appendices. The use of hands-on experiments that were easily adaptable to the 4th grade classroom and the comfortable atmosphere for discussion appear to have contributed the most to a successful workshop.     

自闭症视障儿童的个案评估

视障教育教师团队使用了 5个评定表 ,对一名刚入学的自闭症视障儿童进行评估和分析 ,发现 :该学生功能性听力异常、触觉有过敏倾向、言语无法表达、情绪和行为异常 ,但智力正常、人际关系良好、身体发育正常 ,该学生被诊断为自闭症视障儿童。针对个案评估结果 ,提出了合理的教育对策。     

蒙古族伦理思想概述

蒙古族是一个富有道德情感和道德传统的民族。蒙古族传统伦理思想是指蒙古族历史上各种伦理思想和道德观念的总称,是中国传统伦理思想的重要组成部分。蒙古族传统伦理思想在蒙古族的历史典籍、史著、史诗及格言、谚语、礼仪礼节等诸多方面均有广泛的反映,千百年来在蒙古族人们的思想观念和行为方式中起着规范与准则的作用。在全面建设小康和谐社会,实现各民族共同团结奋斗、共同繁荣发展,开创中国特色社会主义事业新局面的今天,认真发掘、整理、继承和弘扬蒙古族传统伦理道德思想及其文化,无疑是一项意义深远的工作。     

对高等院校"学生评教"的认识与实践

从提高教学质量的角度,对高校教育评估体系中"学生评教"的问题作了较为详细的探讨,并就如何有效地开展"学生评教"的实践活动进行了实例分析与阐述.