极限概念教学探索

极限概念教学是《高等数学》课程教学中的重点及难点.本文在分析极限概念的特性和当前极限教学现状的基础上,探索了极限教学,提出了在课堂教学中应注重的几个环节.     

极限概念教学难点分析及其突破策略

多年来,我国不少学者就极限概念教学难的问题做了大量研究,但该问题并未得到根本解决。通过对极限概念教学进行全面系统的研究,将会发现,在我国的教材体系下,极限概念教学的最大特点是难点多而密集。具体表现在极限的精确定义被高度形式化,且逻辑结构复杂、极限精确定义种类繁多、用精确定义验证极限的证明形式独特、证明技巧性强等方面。因此,为使极限概念教学难的问题得到根本解决,需采取充分铺垫、分散难点、淡化形式、借助直观、梯式演练和因材施教等策略。     

非ε-极限理论与微积分的教学改革

讨论了由第一作者提出的“非ε-极限理论”,它所提出的缘由、理论体系 ,它的合理性 ,它所需要加以解决的问题及其改进方案 .同时 ,还介绍了第二作者根据这种理论编写的教材《新微积分学》及其在教学中的实践效果 .     

基于Matlab的数学分析极限概念教学实践

极限概念是数学分析理论的基础,贯穿数学分析教学的始终,在数学分析的理论体系中占有十分重要的地位.由于极限概念的严谨性和抽象性,在教学实践当中发现学生对极限概念难以理解.本文借助Matlab软件的图形处理功能,将数列极限,一元函数极限以及多元函数极限的形成过程展示出来,从而强化学生对极限概念的理解.     

基于Matlab的数学分析极限概念教学实践

极限概念是数学分析理论的基础,贯穿数学分析教学的始终,在数学分析的理论体系中占有十分重要的地位.由于极限概念的严谨性和抽象性,在教学实践当中发现学生对极限概念难以理解.本文借助Matlab软件的图形处理功能,将数列极限,一元函数极限以及多元函数极限的形成过程展示出来,从而强化学生对极限概念的理解.     

基于“以学为中心”的数列极限教学设计研究

本文选取数列极限的定义这一部分内容,基于“以学为中心”教学理念介绍如何设计数列极限定义的教学过程,从九个环节进行设计旨在使学生更好的理解掌握数列极限的本质和内涵,达到以学为中心的教学目标.     

HPM视角下极限概念的教学案例

本文展示教学案例"数学史融入极限概念教学"的设计、实施和评价过程.从学生认知、思想方法和数学史三个维度来设计课堂教学,经试验和调查,数学史材料有机的融入到极限概念教学中有助于学生更好地理解极限的概念,并总结出数学史融入数学教学的一般流程.     

从应用角度谈两个重要极限教学

两个重要极限,在微积分中具有重要作用.但传统教学往往侧重于理论证明和例题讲解,忽略了它们的应用.本文通过"割圆术"与第一个重要极限、银行复利与第二个重要极限,阐述两个重要极限的应用,以期引起对两个重要极限实际应用的重视.     

“数列的极限（第一课时）”教学设计与反思

一、教学目标 1.通过具体例子使学生感到需要引入一种新的定义——极限,能初步理解极限的定义. 2.运用文字、图形、符号语言表述数列的极限,领略无限逼近的思想. 3.能用极限的观点看问题——不能立刻做到,可以慢慢靠近,要有锲而不舍的“极限精神”. 二、教学重点 初步理解极限定义,能解答简单问题. 三、教学难点 通过图形语言,加深对数列的极限的描述性定义的理解,逐步过渡到用符号语言表述定义.     

ISO2859与GB2828的一些差异

ISO2859是国际标准<计数抽样检查程序及表>的代号, GB2828是国家标准<计数抽样检查程序及抽样表>的代号。从单纯用于连续提交批的调整型抽样检查方案来说,它们是基本一致,大同小异。但若全面比较两个标准,需注意下列一些差别。 一、设计思想的差别 ISO-2859主要是设计为连续提交批的调整型抽样方案。但也为孤立批的标准型方案(或极限质量LQ方案)和挑选型抽样方案的使用提供了一些辅助数据。就是表V-平均检出质量上限系数,表Ⅵ-极限质量Pa=10%和表Ⅻ-极限质量 Pa= 5%。 GB2828则是只适用连续提交批的调整型抽样方案,因此,没有上述三组…     

On intermediate inquisitive and dependence logics: An algebraic study

This article provides an algebraic study of intermediate inquisitive and dependence logics. While these logics are usually investigated using team semantics, here we introduce an alternative algebraic semantics and we prove it is complete for all intermediate inquisitive and dependence logics. To this end, we define inquisitive and dependence algebras and we investigate their model-theoretic properties. We then focus on finite, core-generated, well-connected inquisitive and dependence algebras: we show they witness the validity of formulas true in inquisitive algebras, and of formulas true in well-connected dependence algebras. Finally, we obtain representation theorems for finite, core-generated, well-connected, inquisitive and dependence algebras and we prove some results connecting team and algebraic semantics.     

信用传染违约Aalen加性风险模型

本文考虑了基于加性风险模型的信用风险违约预报模型,不但考虑了宏观因素和公司个体因素,并且通过引入行业因素来刻画公司间可能存在的不同于宏观因素的信用传染效应,由此克服了以往模型对违约相关性的低估.本文在参数加性风险模型下给出极大似然估计及渐近性,提出两种估计方法并比较二者表现,得到最优权估计更加有效.同时本文还考虑了半参数的风险模型,并基于鞅的估计方程得到其估计及渐近性,均得到不错的结果.     

Optimal control of nonlinear evolution inclusions

In this paper, we study the optimal control of nonlinear evolution inclusions. First, we prove the existence of admissible trajectories and then we show that the set that they form is relatively sequentially compact and in certain cases sequentially compact in an appropriate function space. Then, with the help of a convexity hypothesis and using Cesari's approach, we solve a general Lagrange optimal control problem. After that, we drop the convexity hypothesis and pass to the relaxed system, for which we prove the existence of optimal controls, we show that it has a value equal to that of the original one, and also we prove that the original trajectories are dense in an appropriate topology to the relaxed ones. Finally, we present an example of a nonlinear parabolic optimal control that illustrates the applicability of our results.This research was supported by NSF Grant No. DMS-88-02688.     

Forecasting the integration of immigrants

In this research, we develop and introduce a theoretical and mathematical forecasting framework of immigrant integration using immigrant density as a single driver. First, we introduce the integration concepts we aim at forecasting. Thereafter, we introduce a theoretical and mathematical model of the relationship between integration and immigrant density. Based on this model, we develop a methodological forecasting framework. We test the framework using immigrant integration data from Spain. We produce the forecasts, and conduct the proper evaluation of them. Finally, we conclude with a brief discussion of the wider implications of our results.     

Exploring an unknown graph

We wish to explore all edges of an unknown directed, strongly connected graph. At each point, we have a map of all nodes and edges we have visited, we can recognize these nodes and edges if we see them again, and we know how many unexplored edges emanate from each node we have visited, but we cannot tell where each leads until we traverse it. We wish to minimize the ratio of the total number of edges traversed divided by the optimum number of traversals, had we known the graph. For Eulerian graphs, this ratio cannot be better than two, and two is achievable by a simple algorithm. In contrast, the ratio is unbounded when the deficiency of the graph (the number of edges that have to be added to make it Eulerian) is unbounded. Our main result is an algorithm that achieves a bounded ratio when the deficiency is bounded. © 1999 John Wiley & Sons, Inc. J Graph Theory 32: 265–297, 1999     

Asymptotic behaviour of a closed‐loop thermosyphon with linear friction and viscoelastic binary fluid

Viscoelastic fluids represent a major challenge both from an engineering and from a mathematical point of view. Recently, we have shown that viscoelasticity induces chaos in closed‐loop thermosyphons even when we consider binary fluids, this is, when we consider a solute in the fluid, as water and antifreezes, for example. In this work, we consider a linear friction law, and we show that in this case with the addition of a solute to the fluid we can prove, under some conditions, chaotic asymptotic behavior for suitable geometry of the circuit and heat flux or ambient temperature functions.     

Nonlinear elliptic differential equations with multivalued nonlinearities

In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all ℝ. Assuming the existence of an upper and of a lower solution, we prove the existence of a solution between them. Also for a special version of the problem, we prove the existence of extremal solutions in the order interval formed by the upper and lower solutions. Then we drop the requirement that the monotone nonlinearity is defined on all of ℝ. This case is important because it covers variational inequalities. Using the theory of operators of monotone type we show that the problem has a solution. Finally in the last part we consider an eigenvalue problem with a nonmonotone multivalued nonlinearity. Using the critical point theory for nonsmooth locally Lipschitz functionals we prove the existence of at least two nontrivial solutions (multiplicity theorem).     

Hereditary atomicity in integral domains

If every subring of an integral domain is atomic, we say that the latter is hereditarily atomic. In this paper, we study hereditarily atomic domains. First, we characterize when certain direct limits of Dedekind domains are Dedekind domains in terms of atomic overrings. Then we use this characterization to determine the fields that are hereditarily atomic. On the other hand, we investigate hereditary atomicity in the context of rings of polynomials and rings of Laurent polynomials, characterizing the fields and rings whose rings of polynomials and rings of Laurent polynomials, respectively, are hereditarily atomic. As a result, we obtain two classes of hereditarily atomic domains that cannot be embedded into any hereditarily atomic field. By contrast, we show that rings of power series are never hereditarily atomic. Finally, we make some progress on the still open question of whether every subring of a hereditarily atomic domain satisfies ACCP.     

修正的IPA算法的建立及在不等式约束凸优化问题中的应用

本文首先对IPA算法进行了修正，并证明了修正IPA算法的收敛性，然后将修正后的IPA应用到不等式约束凸优化问题中得到新的内点算法，并与传统的障碍函数法作了比较，从理论上体现了新算法的优势，并给出了其工程解求解法以及收敛性的证明．     

Orderings and Probability Functionals Consistent with Preferences

This paper unifies the classical theory of stochastic dominance and investor preferences with the recent literature on risk measures applied to the choice problem faced by investors. First, we summarize the main stochastic dominance rules used in the finance literature. Then we discuss the connection with the theory of integral stochastic orders and we introduce orderings consistent with investors' preferences. Thus, we classify them, distinguishing several categories of orderings associated with different classes of investors. Finally, we show how we can use risk measures and orderings consistent with some preferences to determine the investors' optimal choices.