Two sample applications of a classical isoperimetric problem of the calculus of variations to fluid mechanical problems in fluidization and spouting

This paper is devoted to outlining precisely the basic mathematics of a classical isoperimetric problem of the calculus of variations and showing how significant fluid mechanical problems in fluidization and spouting can be addressed using this approach.     

Surrogate-based modeling and dimension reduction techniques for multi-scale mechanics problems

Successful modeling and/or design of engineering systems often requires one to address the impact of multiple "design variables" on the prescribed outcome.There are often multiple,competing objectives based on which we assess the outcome of optimization.Since accurate,high fidelity models are typically time consuming and computationally expensive,comprehensive evaluations can be conducted only if an efficient framework is available.Furthermore,informed decisions of the model/hardware’s overall performance rely on an adequate understanding of the global,not local,sensitivity of the individual design variables on the objectives.The surrogate-based approach,which involves approximating the objectives as continuous functions of design variables from limited data,offers a rational framework to reduce the number of important input variables,i.e.,the dimension of a design or modeling space.In this paper,we review the fundamental issues that arise in surrogate-based analysis and optimization,highlighting concepts,methods,techniques,as well as modeling implications for mechanics problems.To aid the discussions of the issues involved,we summarize recent efforts in investigating cryogenic cavitating flows,active flow control based on dielectric barrier discharge concepts,and lithium(Li)-ion batteries.It is also stressed that many multi-scale mechanics problems can naturally benefit from the surrogate approach for "scale bridging."     

高考中的有限、无穷与所有型问题解析

众所周知,恒成立问题在函数与不等式中一直备受高考的青睐,它很好地考查了分类与分步、数形结合、化归与转化、函数与方程等数学思想.而近年来,此类问题又延伸到了其它领域并作了进一步的拓展升华,出现了与有限、无穷和所有（恒成立）有关的考题.     

用面积法解题

用面积法解题就是根据题目给出的条件,利用等积变换原理有和关面积计算的公式、定理或图形的面积关系进行解题.所谓高效解题就是转化的环节少一些,不走弯路.有时我们选用面积法将问题转化,就能恰到好处地达到这一目的.     

命名等高点 关注临界性

在学习的过程中，我们发现某些典型性问题，它具有一定的难度，隔一段时间再做类似问题时又极易出错，并且在阶段性的精简提炼笔记或错题集时，以及平时的同学间、师生问的交流时，又不易简捷地说清具体是哪类问题，原因是这类问题还从来没有其约定俗成的名称．对此，笔者建议不妨发挥自己的创造力，对这些问题大胆命名，     

巧用转化法解决椭圆问题

椭圆是一种规则图形，但关于椭圆的问题解决起来却并不方便：通常的解析法中繁长的推导过程不仅易使人陷入困境，而且也极容易使人出错，现在我向大家介绍一种巧妙解决椭圆问题的方法——转化法。     

一类特殊初值柯西问题的简易解法

通过对初始条件为平面波的三维波动方程柯西问题的研究,利用变量变换,将三维波动方程柯西问题转化为一维波动方程柯西问题,以利用达朗贝尔公式来求解,从而避开了使用复杂的泊松公式.     

例说建立递推关系式解题

在解某些数学问题时,若能根据问题的实质和特征,建立递推关系式,就会使问题很巧妙地得到解决.下面举例说明,供读者参考.     

浅谈物理规律教学的有效性

美国的著名学者波斯纳（Posner）提出的教师成长公式：成长=经验＋反思，新课标的实行，要求我们教师必须要从单纯的知识传递者走向研究者、反思者。在新时期，我们教师不仅仅需要有较为丰富的专业学识，还必须要善于对教学问题进行研究和反思。面对新形式，我们教师必须要积极地对自己的学科教学进行反思。本文主要就在新课标下高中物理教学进行反思。