了解积分——求和

求一个函数的黎曼积分,实际上就是一个分割、近似代替、求和、取极限的过程.求和运算是整个积分计算的轴心.就积分四部曲中的求和问题,做一个一般性的讨论.文中使用的是分析和讨论的语言,不去追求数学语言本身的严格性.目的不仅是探讨求和这个步骤,在黎曼积分意义下具体实现的过程和隐含的内容,而且对一般的积分中的求和实现的可能性、应该满足的条件、实现的过程,以及应该注意那些基本问题,也做一点儿逻辑上的探讨.已达到以知识为媒介,提高认知能力的目的.     

了解积分——由积分的概念所想到的问题

主要是由黎曼积分的概念出发,提出了人们在学习积分中应该注意的一些问题.文中将这些问题分成了几个层次,从而帮助学习积分的人们在学习知识的同时,充分发挥自己的想象,从而达到不仅仅记住概念和相关的知识,而且可以了解到这样做的必要性,以及隐藏在这些知识背后的逻辑上的深层次的必然联系,从而达到开阔读者思维和兴致的目的,也为初学者在学习中应该如何思考,进而如何创造新的知识,提供一个可以借鉴的思考方法和途径.     

黎曼积分与极限交换顺序的条件

<正> 在目前通用的数学分析或高等数学教材中,只介绍了能保证黎曼积分与极限可交换顺序的一致收敛条件.众所周知,一致收敛是一个很强的条件,做为一致收敛的自然推广,王晓斐在中引进了容度收敛的概念并研究了极限函数的黎曼可积性问题.在此工作的基础上我们能容易地给出黎曼积分与极限交换顺序的较弱条件。对于已掌握一致收敛概念并没有机会学习实变函数的大多数工科大学生来说,本文不难理解并且可看成是对所学知识的有益补充.     

切口宜求小，视角力求新——数学复习课教学新思维

在复习课的课堂中,如何让每个层次的学生都能有所得,如何实施有效的课堂内外教学策略,保持学生对数学的兴趣,让学生感觉到每节数学课都有惊喜,是一个非常值得探讨的问题．笔者认为复习课不仅仅是对知识的回顾与整理,更多承载着的是思想方法的沟通．因此,复习课应该首先做到有所侧重,集中力量解决某一块知识或某一类问题．     

黎曼可积函数列的极限理论及应用

对黎曼可积函数列的极限函数的可积性进行讨论．运用黎曼积分自身的理论依次证明了：一致收敛函数列的极限函数的黎曼可积性,黎曼积分下的控制收敛定理和广义积分下的控制收敛定理。并给出了一些应用例子．     

不等式恒成立问题中参数求解的四大策略

恒成立条件下不等式参数的取值范围问题，涉及的知识面广，综合性强，同时数学语言抽象，如何从题目中提取可借用的知识模块往往捉摸不定，难以寻觅，是同学们学习的一个难点，同时也是高考命题中的一个热点．     

培养学生创新思维能力的教学设计与实践

培养学生数学思维创新能力、数学理解创新能力、数学应用创新能力一直是大学数学教学所追求的高要求、高目标.在教学过程中如何通过重构教学内容、革新教学方法来实现培养学生用数学语言、数学知识、数学技术去描述、解释自然现象是大学数学课程教学改革的一个主方向.本文通过一个具体的教学实例来分享如何在线性代数课程教学中实现培养学生的数学思维创新和数学理解创新.     

一节“应用问题”研究课的设计与评述

一节“应用问题”研究课的设计与评述设计：丁益祥（北京陈经论中学）评述：郭立昌（北京市教育局教研部）如何培养学生应用数学的意识，提高解决数学应用问题的能力，是一个值得探索的问题．我们认为，首先要在平时教学中，注重知识形成过程。加强数学语言训练，培养应用...     

创设合理数学问题情境的方法与途径

数学问题情境是学生掌握知识、形成能力、发展心理品质的重要源泉,是沟通现实生活与数学学习、具体问题与抽象概念之间的桥梁．一个良好的数学问题情境,能集中学生的注意力,诱发学生思维的积极性,引起学生更多的联想,也比较容易调动起学生已有的知识、经验、感受和兴趣,从而更加主动地参与知识的获取过程、问题的解决过程．那么,在数学教学中,如何创设合理的问题情境呢？     

用好必要条件 优化解题策略

一、问题的提出 寻求“最优化”的解题策略是数学教学的一个重要目标．可是,现实中“小题大做”、“大题繁做”的案例比比皆是．因此,经常性地对解题策略进行研讨,避免“小题大做”,甚至实现“大题小做”,应该成为数学教学研究的一个永恒主题．     

C 1 Quintic Splines on Type-4 Tetrahedral Partitions

Starting with a partition of a rectangular box into subboxes, it is shown how to construct a natural tetrahedral (type-4) partition and associated trivariate C ¹ quintic polynomial spline spaces with a variety of useful properties, including stable local bases and full approximation power. It is also shown how the spaces can be used to solve certain Hermite and Lagrange interpolation problems.     

跳汰机的性能及统计模型

在煤用重选设备评定的国际标准（ＩＳＯ９２３）和以之为蓝本的国家标准（ＧＢ／Ｔ１５７１５）中的第一项评定指标“可能偏差”及和其有关的“不完善度”的确定是由以下步骤决定：１．由仅仅一次浮沉试验取得一组数据（一个观察值）并由此计算两段分离所得产品的分配率;２．用手工凭想象中的“Ｓ型曲线”把分配率中的两组６ 至８ 个点联起来得到两条“分配曲线”;３．由这两条粗糙的曲线“量出”各自的２５％ 和７５％ 分位点,以此得到能反映重选设备分离能力好坏的两个指标：“可能偏差”Ｅ和“不完善度”Ｉ,很难想象,这样由一个观察值得到的指标并通过没有模型的手工绘图而得到的结果会有任何实际意义,本文建议利用尽可能多的观察值来拟合ｌｏｇｉｓｔｉｃ回归模型,并依此得到分配曲线和计算出参数Ｅ和Ｉ,本文还利用一组实际数据来说明我们方法的合理性     

一种连续的谱聚类优化模型

聚类与图的划分问题在大数据分析中有着重要的应用.这类问题一般被描述为组合优化问题,因此较难快速求解.本文设计了一种新的连续优化模型,并提出了一种块坐标下降算法,数值实验显示我们的新方法在求解聚类与图的划分问题上很有潜力.我们还更进一步分析了我们的连续优化模型和组合优化模型的关系.     

矩阵的分块初等变换与分块初等阵及其应用

讨论了矩阵分块初等变换和分块初等阵的定义和性质,利用这一工具研究了行列式的分块运算,分块矩阵的求逆和对称阵的分块合同变换等问题.     

A Branch-and-Bound Based Method for Solving Monotone Optimization Problems

Monotone optimization problems are an important class of global optimization problems with various applications. In this paper, we propose a new exact method for monotone optimization problems. The method is of branch-and-bound framework that combines three basic strategies: partition, convexification and local search. The partition scheme is used to construct a union of subboxes that covers the boundary of the feasible region. The convexification outer approximation is then applied to each subbox to obtain an upper bound of the objective function on the subbox. The performance of the method can be further improved by incorporating the method with local search procedure. Illustrative examples describe how the method works. Computational results for small randomly generated problems are reported. Dedicated to Professor Alex Rubinov on the occasion of his 65th birthday. The authors appreciate very much the discussions with Professor Alex Rubinov and his suggestion of using local search. Research supported by the National Natural Science Foundation of China under Grants 10571116 and 10261001, and Guangxi University Scientific Research Foundation (No. X051022).     

How to deal with the unbounded in optimization: Theory and algorithms

The aim of this survey is to show how the unbounded arises in optimization problems and how it leads to fundamental notions which are not only useful for proving theoretical results such as convergence of algorithms and the existence of optimal solutions, but also for constructing new methods.     

Star partitions on graphs

Given an undirected graph, a star partition is a partition of the nodes into subsets with at least two nodes so that the subgraph induced by each subset has a spanning star. Star partitions are related to well-known problems concerning domination in graphs and edge covering. We focus on the Constrained Star Partition Problem (CSP) that asks for finding a star partition of given cardinality. The problem is new and presents interesting peculiarities. We explore the relation between the cardinalities of star partitions and domatic bipartitions, showing that there are star partitions of any cardinality between minimum and maximum values, and that a similar but weaker result holds for domatic bipartitions. We study the computational complexity of different versions of star partition and domatic bipartition problems, proving that most of them, in particular CSP, constrained domatic bipartition and balanced domatic bipartition, are NP-complete. We also show that star partition problems are polynomial on trees and, more generally, on bounded treewidth graphs. We introduce an integer linear programming formulation that defines a polytope containing all the star partitions of a graph, showing that its vertices have only integral components for trees, which implies that linear programming can be used to solve weighted star partition problems on trees.     

Voronoi diagrams and arrangements

We propose a uniform and general framework for defining and dealing with Voronoi diagrams. In this framework a Voronoi diagram is a partition of a domainD induced by a finite number of real valued functions onD. Valuable insight can be gained when one considers how these real valued functions partitionD ×R. With this view it turns out that the standard Euclidean Voronoi diagram of point sets inR ^d along with its order-k generalizations are intimately related to certain arrangements of hyperplanes. This fact can be used to obtain new Voronoi diagram algorithms. We also discuss how the formalism of arrangements can be used to solve certain intersection and union problems.     

New LP bound in multivariate Lipschitz optimization: Theory and applications

Most numerically promising methods for solving multivariate unconstrained Lipschitz optimization problems of dimension greater than two use rectangular or simplicial branch-and-bound techniques with computationally cheap but rather crude lower bounds.Generalizations to constrained problems, however, require additional devices to detect sufficiently many infeasible partition sets. In this article, a new lower bounding procedure is proposed for simplicial methods yielding considerably better bounds at the expense of two linear programs in each iteration. Moreover, the resulting approach can solve easily linearly constrained problems, since in this case infeasible partition sets are automatically detected by the lower bounding procedure.Finally, it is shown that the lower bounds can be further improved when the method is applied to solve systems of inequalities. Implementation issues, numerical experiments, and comparisons are discussed in some detail.The authors are indebted to the Editor-in-Chief of this journal for his valuable suggestions which have considerably improved the final version of this article.