力学中"两体碰撞"的程序实现

“两体碰撞”是力学教学中的重要内容，也是教学中的一个难点，本以物理规律为基础，提出了在一般情况下如何用计算机模拟“两体碰撞”的程序实现方法，详细介绍了由程序控制碰撞初值进行多次碰撞的基本算法以及编写程序应注意的问题；有坐标变换方法有效地解决了任意条件下的两体碰撞问题，使教材中正碰和斜碰的分离问题有机地统一起来。     

利用两个结论速解弹性正碰速度问题

纵观高考物理压轴题中,对心弹性碰撞一直是考查动量与能量方面知识的热点题型。对这类正碰问题常常会指导学生从动量守恒,机械能守恒方面去求解,这就要求学生有比较扎实的数学知识,但由于运算量过大,仍然存在因运算出错而失分的现象。我们总结出完全弹性碰撞的两点结论,大大提升了学生的解题速度和正确率。     

In defense of scientific autonomy: The two cultures revisited

This article is adapted from a lecture delivered on April 25, 1988 at a meeting sponsored by the National Association of Scholars, at the University of Texas in Austin.     

Fun with balls and coins

Even elementary probability has a lot of interesting things to offer to the students to get excited and think about. Unfortunately our curricula are generally designed in such a way that interesting things are carefully left out. Even if the material is touched upon briefly, the discussion is reduced to simple calculation of ratios devoid of any meaning. In this article we discuss two interesting models in probability. We just throw balls into boxes as dictated by tossing coins, nothing more than that.     

Realtime vision-based surface defect inspection of steel balls

In the proposed system for online inspection of steel balls, a diffuse illumination is developed to enhance defect appearances and produce high quality images. To fully view the entire sphere, a novel unfolding method is put forward based on geometrical analysis, which only requires one-dimensional movement of the balls and a pair of cameras to capture images from different directions. Moreover, a realtime inspection algorithm is customized to improve both accuracy and efficiency. The precision and recall of the sample set were 87.7% and 98%, respectively. The average time cost on image processing and analysis for a steel ball was 47 ms, and the total time cost was less than 200 ms plus the cost of image acquisition and balls’ movement. The system can sort 18 000 balls per hour with a spatial resolution higher than 0.01 mm.     

巧析碰撞问题

动量知识是近年高考的热点内容,一维碰撞问题又是其考查的重点内容之一。本文通过建立碰撞模型形象而直观地描述碰撞的过程和简单又巧妙地分析了碰撞结果。为了避免求解方程组的繁琐,本文提出了极其简易的解题方法。     

高速碰撞仿真计算的优化方法

针对高速碰撞仿真系统中计算量较大的有限元计算部分,建立了并行有限元模型和区域划分原则,利用逐元法(Element by Element,EBE)分析有限元结构和单个有限元的物理量,利用区域划分方法对有限元网格进行划分,并采用中心差分法求解拉格朗日运动方程,用以模拟圆柱形物体高速碰撞刚性墙的过程。分析了多核CPU架构的基本通信原理,提出了1种动态负载均衡策略,能够优化多核架构上高速碰撞过程中有限元计算的运行效率,选用MPICH2和FORTRAN编写了仿真计算程序。经过多次实验,该优化方法将有限元计算程序运行效率平均提高了8.7%以上。     

目标教学新探索

<目标教学新论>一书,是广西教育学院教研部10年来进行目标教学实验研究的理论探讨的结晶.书名之所以定为"新论",我想,一是因为本书概括了广西广大中小学教师在实施目标教学中的许多新鲜经验;另一方面,更为重要的是,本书对当前教学改革面临的新问题进行了探讨.这些新问题,当然也是目标教学面临的新问题.对这些新问题的探讨,我以为是非常有意义的,很可能由此开了目标教学实验的新生面,同时对现实的教学实践也会产生深远的影响.     

Concept image revisited

Concept image and concept definition is an important construct in mathematics education. Its use, however, has been limited to cognitive studies. This article revisits concept image in the context of research on undergraduate students’ understanding of the derivative which regards the context of learning as paramount. The literature, mainly on concept image and concept definition, is considered before outlining the research study, the calculus courses and results which inform considerations of concept image. Section 6 addresses three themes: students’ developing concept images of the derivative; the relationship between teaching and students’ developing concept images; students’ developing concept images and their departmental affiliation. The conclusion states that studies of undergraduates’ concept images should not ignore their departmental affiliations. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Radio drama revisited

The purpose of this study was to investigate the validity of using two variables, topic importance and non‐commitment latitude, in operational definitions of enduring involvement. Results indicated that topic importance was an acceptable variable to consider in such a definition, but that the latitude of non‐commitment was constant across topics. Rather than serving to identify levels of enduring involvement, the size of respondents' latitude of non‐commitment appeared to be a personal characteristic of the respondents.     

再论孔子的“君子儒”之教

孔子所谓"君子之德",属于伦理道德,有别于习俗道德.在道德人格意义上,非"君子"即"小人"、非"小人"即"君子"的观念,不符合客观事实.     

弹性碰撞的几何解释

用几何方法可使弹性碰撞问题显得深刻而直观,并能方便地获得解析方法不太容易获得的重要信息。     

Gap analysis revisited

Gap analysis is an important part of the performance improvement process that fits into the International Society for Performance Improvement's 10 Standards of Performance Technology, Standard 5. This article discusses the need to set a reasonable goal to motivate people to close the performance gap and provide a milestone for measuring progress as the gap is closed. It also provides insight into the need to identify performance trends that led to the current level of performance as we define the performance gap.