多项式混沌方法在偶然不确定度量化中的应用

复杂工程建模与模拟中必然存在误差与不确定度,分析与辨识其不确定度的来源,对不确定度进行量化,对建模与模拟可信度评估具有重要意义。本文给出建模与模拟中误差与不确定度的概念及不确定度的量化过程,并以质量弹簧阻尼系统为例说明量化偶然不确定度的过程,验证了非嵌入多项式混沌方法在非光滑系统不确定度量化中的有效性,对建模与模拟中不确定度量化具有重要的参考价值。     

数学分析中一类与存在性有关的错误解法原因剖析

从"忽略极限定义中δ对ε的依赖""忽略介值与中值定理中介值点与中值点对其它因素的依赖""二元函数中的存在性问题与一致性"等三个方面深入剖析数学分析中一类与存在性有关的错误解法,反思在教学中应注意的地方并给出一些对策与教学建议.     

有限元理论中的科学研究方法

有限元方法是目前计算数学最活跃的分支之一 ,关于它的基础数学理论和数值实现广泛受到理论界和工程界的重视 .本文为作者在对有限元方法的学习研究中 ,结合自然辩证法、科学技术革命与当代社会、马克思主义哲学原理课程的学习 ,对该领域中几对范畴如连续与离散、有限与无限、部分与整体、协调与非协调、空间与时间复杂度之间关系的认识和体会 .揭示了科学方法论对该领域研究探索中的指导作用 .     

谱与Tilings关系中的测度估计和平移对

本文将在两种特有的情形下研究谱与tilings之间的关系.首先,估计和比较谱与tilings关系中集合的Lebesgue测度,这包括一些不能直接用密度方法所得结果的推广,以及在正交对、填充对与覆盖对中集合的Lebesgue测度的比较.其次,明确了平移对(D,∧+Г)与(D+Г,∧)之间的一些谱与tilings关系.这里的研究是基于谱与tilings的基本性质,与共轭Fuglede猜想密切相关.     

G-分次环与G-集的冲积(Smash Product)

对任意群G,[1]中研究了G-分次环与可迁有限G-集的冲积.在本文中我们对任意可迁G-集A,讨论了G-分次环R与G-集A的冲积,从而推广了[2][3]中给出的关于G-分次环与群G的冲积的主要结果.     

从例题中学习

例题,作为巩固和加深对所学数学知识与方法的理解的载体,在课本中占有重要的位置.在数学学习中,采取什么样的方法来进行例题的学习,将直接影响到对数学知识与方法的理解掌握,从而导致迥异的数学学习效果.从课本的一道例题中,除了从表面上的学习概念、公式与定理的运用之外,我们还可以从中学到什么？     

不同教材中高等数学概念的辩析

对同济六版高等数学与西安交大版高等数学中关于多元函数微分学中概念的比较分析,结合例题给出它们区别与联系.     

G-分次环与G-集的冲积(Smash Product)

对任意群G,[1]中研究了G-分次环与可迁有限G-集的冲积.在本文中我们对任意可迁G-集A,讨论了G-分次环R与G-集A的冲积,从而推广了[2][3]中给出的关于G-分次环与群G的冲积的主要结果.     

数学课堂概念引入的过渡与衔接策略

平常在听课与评课的过程中,许多新教师会感叹执教教师教学环节流畅自然,教学内容一气呵成,感叹老教师的教学设计与课堂艺术．而关注这一现象,其视角的落脚点就是关注教师在课堂设计中对知识的合理建构,关注教学内容的呈现是过渡与衔接．尤其是数学概念课课堂教学中,从情景与概念（性质）,到例题与小结,最后到作业,课堂结构明显,如何处理好各环节的衔接和过渡,能充分体现教师的教学水平．笔者结合教学实践,对在数学概念课堂教学中引入教学内容时的过渡与衔接进行了研究．     

高等数学中几个概念之间的关系

对高等数学中导数的单侧极限与单侧导数、可导与连续、函数单调性与函数极值之间的关系进行探讨,对相关命题的正误进行辨析,以利于学生对概念的理解和相关知识的掌握.     

Problem Formulation: Insights from Student Generated Questions

This article describes an exploration of one facet of problem formulation. Prospective elementary and secondary teachers were presented with a mathematical situation consisting of data and conditions, but no questions were presented. They were asked to create questions that could be answered using the given information. In the spirit of exploration, this paper analyzes the student-formulated questions from two perspectives—the nature of the information contained within the questions posed and the responses which those questions elicited. A careful analysis of questions posed by students will enable education professionals to understand and promote better problem posing in mathematics classrooms.     

Student teachers’ types of probing questions in inquiry-based mathematics teaching with and without GeoGebra

Previous studies have produced several typologies of teacher questions in mathematics. Probing questions that ask students to explain are often included in the types of questions. However, only rare studies have created subtypes for probing questions or investigated how questioning differs depending on whether technology is used or not. The aims of this study are to elaborate on different ways of asking students to give explanations in inquiry-based mathematics teaching and to investigate whether questioning in GeoGebra lessons differs from questioning in other lessons. Data was collected by video recording 29 Finnish mathematics student teachers’ lessons in secondary and upper secondary schools. The lesson videos were coded for the student teachers’ probing questions. After this, categories for the types of probing questions were created, which is elaborated in this paper. It was found that the student teachers who used GeoGebra emphasized conceptual probing questions during the explore phase of a lesson slightly more than the other student teachers.     

Limit sets for maps of the circle

A trick which reduces some questions concerning the dynamics of self-maps of the circle to similar questions about self-maps of the interval is suggested and applied to answer two questions of Block and Coppel.     

一种基于二部图的试题知识点标注方法

针对在线教育中试题知识点自动标注问题,本文提出了一种基于二部图的试题知识点标注方法。首先,为了合理划分知识点粒度,本文构建了知识点知识图谱来融合知识点;其次,基于教材等语料抽取知识点与特征词二部图和试题与特征词二部图,并利用TF-IDF公式计算知识点与特征词、试题与特征词之间的边权,以构建试题-知识点二部图模型;再次,提出词频加权的相似性度量方法计算试题和知识点之间的相似度,将相似度最高的知识点作为试题知识点标签。最后,以某在线教育平台提供的高中历史试题为实验数据集进行数值实验,实验结果表明该方法的效果显著优于朴素贝叶斯、K最近邻、随机森林以及支持向量机。     

Creating discussions with classroom voting in linear algebra

We present a study of classroom voting in linear algebra, in which the instructors posed multiple-choice questions to the class and then allowed a few minutes for consideration and small-group discussion. After each student in the class voted on the correct answer using a classroom response system, a set of clickers, the instructor then guided a class-wide discussion of the results. We recorded the percentage of students voting for each option on each question used in 18 sections of linear algebra, taught by 10 instructors, at 8 institutions, over the course of 5 years, together recording the results of 781 votes on a collection of 311 questions. To find the questions most likely to provoke significant discussions, we identify the six questions for which votes were most broadly distributed. Here we present these questions, we discuss how we used them to advance student learning, and we discuss the common features of these questions, to identify why they were so good at stimulating discussions.     

Cultivating inquiry about space in a middle school mathematics classroom

During 46 lessons in Euclidean geometry, sixth-grade students (ages 11, 12) were initiated in the mathematical practice of inquiry. Teachers supported inquiry by soliciting student questions and orienting students to related mathematical habits-of-mind such as generalizing, developing relations, and seeking invariants in light of change, to sustain investigations of their questions. When earlier and later phases of instruction were compared, student questions reflected an increasing disposition to seek generalization and to explore mathematical relations, forms of thinking valued by the discipline. Less prevalent were questions directed toward search for invariants in light of change. But when they were posed, questions about change tended to be oriented toward generalizing and establishing relations among mathematical objects and properties. As instruction proceeded, students developed an aesthetic that emphasized the value of questions oriented toward the collective pursuit of knowledge. Post-instructional interviews revealed that students experienced the forms of inquiry and investigation cultivated in the classroom as self-expressive.     

用基础解系解某些条件极值问题

通过对线性的目标函数在线性的约束条件下的极值问题的分析,得到这类极值问题一般是不能用拉格朗日乘数法求解.通过用基础解系的方法进行求解这类问题,实例表明,这种方法是可行有效的.     

货运列车的优化编组调度方案与实现方法

针对2008年全国研究生数学建模竞赛C题"货运列车的编组调度问题",首先介绍了问题的背景和问题的构成,并提出了6个要解决的问题;然后概要地分析介绍了解决这6个具体问题的思想方法;接着给出了具体解决问题的实现方法、主要模型和求解思路;最后对参赛队的总体做法和存在问题情况做了较详细的分析,并就与这个题目有关的几个问题做了说明.