一阶导数形式不变性

针对数学教材中由导数基本公式到复合函数求导法则过渡形式不一致现象,提出一阶导数的一致形式、修订复合函数求导法则、给出导数基本公式的一般形式.     

例谈构造法解导数与不等式问题

<正>导数的思想最初是由法国数学家费马提出的,在中学数学中,导数的思想为研究函数的图像和性质起到了重要的作用,是高考数学的重要考点之一,本文从构造法的角度来谈一谈解导数与不等式的问题.一、基本求导法则与公式要想通过题目中的导数构造辅助函数,就必须对基本求导法则与公式非常熟悉,现在把基本求导法则与基本初等函数的导数公式列     

方向导数的计算公式的注记

方向导数本质上也是函数的一种变化率.利用向量的Schmidt正交化方法进行坐标变换,将方向导数转换为对新变量的偏导数,再结合多元复合函数的求导法则,给出方向导数计算公式的一种新的证明.     

反函数导数教学中的两点建议

提出了反函数导数教学中的两点建议:其一是用复合函数的极限运算法则合理解释求导公式的推导中求极限时用到的换元法;其二是在计算反函数的高阶导数时正确分析低阶导数的复合结构.同时为加深学生对求导公式的理解,教学中可引入具体例题验证公式.     

导数公式推导的启发式教学方法

针对一般微积分教材中函数的积、商求导法则、反三角函数的求导公式和参数式函数的二阶求导公式,提供几种简明易懂的启发式教学方法,对导数的运算有很好的参考价值.     

幂指函数的求导法则

<正> 形如y=u(x)~(v(x))(u(x)>0)的函数称为幂指函数。幂指函数属于初等函数的一部分,它是微分学中经常迂到的函数类型之一。求幂指函数的导数通常有两种方法,一是利用“对数求导法”,也即先对函数表达式取对数,然后再求导数;二是利用对数恒等式将幂指函数化为以e为底的复合指数函数形式,再求其导数,本质上都是用复合函数求导法则。先看下面的例子:     

利用偏反函数求解多元隐函数的偏导数

本文利用类比联想给出了一种类似于一元函数利用反函数求导法则的新方法来求解多元隐函数的偏导数,并在此基础上利用多元函数的一阶微分形式不变性得出了以二元函数为例6个偏导数中的某三个满足特殊的链式法则,并将此法则推广到任意n元函数.     

解谈2005年高考导数试题

导数是新教材新增加的内容,是解决数学问题的重要工具,是高考数学的重点内容之一.笔者就05年出现的导数试题作以下点评:一、试题贴近基础,注重理解和推理以导数为背景或依托的试题,虽然有易有难,但通常总是紧贴着导数基础知识(如导数的概念、求导的公式和求导的法则)和导数的简单应用(包括求函数的极值和最值、单调区间),把考查理解能力和推理运算能力作为基本的要求.例1(广东卷)函数f(x)=x3-3x2 1是减函数的区间为()(A)(2, ∞)(B)(-∞,2)(C)(-∞,0)(D)(0,2)本题考查了导数的简单应用,只要根据连续函数在某区间上单调递减,则导数小于零,便…     

扩大的积分微分方程组的解

提出几类扩大的积分微分方程组,利用函数迭代法及变上限函数的求导法则,证明其可积性,得出相应的求解公式.     

有理函数的高阶导数公式

导数是微积分学的重要研究对象,寻求函数的高阶导数公式是困难的,只有极少数类型的函数可以得到高阶导数公式.本文给出了有理函数的高阶导数的公式,我们从分解真分式入手,由于任意一个真分式都可以分解成最高分式之和,再利用导数的运算法则及公式,把复数部分转换为三角式进行化简,进而推算出有理函数的高阶导数的公式.最后本文结合实例对有理函数的高阶求导做出了讨论.     

A version of Hörmander’s theorem for the fractional Brownian motion

It is shown that the law of an SDE driven by fractional Brownian motion with Hurst parameter greater than 1/2 has a smooth density with respect to Lebesgue measure, provided that the driving vector fields satisfy Hörmander’s condition. The main new ingredient of the proof is an extension of Norris’ lemma to this situation.     

关于ζ函数的积分表示

主要研究了ζ函数的积分表示形式;通过解析数论的研究方法,利用黎曼ζ函数方程,给出了关于赫尔维茨ζ函数的埃尔米特公式,利用埃尔米特公式得出关于Γ函数的比内第二表达式,通过ζ函数得出Γ函数一些性质.     

Stochastic motion under G-framework: II. Kinematics

Continuing the study of stochastic motion that we started [11 Zhang, H., and Kannan, D. 2014. Stochastic motion under G-framework: I. Nelson stochastic derivatives. Stoch Anal Appl 32:1067–1096.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]], we present in this article the kinematics of such a motion. We begin by defining the quadratic derivative of an S2-process, and show that this derivative of the Brownian motion captures the variance uncertainty. We show, under certain vanishing derivatives and independence conditions, the martingale properties of an S1-process. Starting with an S1-process, we derive the equation of motion, an Itô equation corresponding to a G-diffusion process.     

A nonlinear stochastic heat equation: Hölder continuity and smoothness of the density of the solution

In this paper, we establish a version of the Feynman–Kac formula for multidimensional stochastic heat equation driven by a general semimartingale. This Feynman–Kac formula is then applied to study some nonlinear stochastic heat equations driven by nonhomogeneous Gaussian noise: first, an explicit expression for the Malliavin derivatives of the solutions is obtained. Based on the representation we obtain the smooth property of the density of the law of the solution. On the other hand, we also obtain the Hölder continuity of the solutions.     

Rough path limits of the Wong-Zakai type with a modified drift term

The Wong-Zakai theorem asserts that ODEs driven by “reasonable” (e.g. piecewise linear) approximations of Brownian motion converge to the corresponding Stratonovich stochastic differential equation. With the aid of rough path analysis, we study “non-reasonable” approximations and go beyond a well-known criterion of [Ikeda, Watanabe, North Holland, 1989] in the sense that our result applies to perturbations on all levels, exhibiting additional drift terms involving any iterated Lie brackets of the driving vector fields. In particular, this applies to the approximations by McShane ('72) and Sussmann ('91). Our approach is not restricted to Brownian driving signals. At last, these ideas can be used to prove optimality of certain rough path estimates.     

基于组合赋权和灰色关联投影法的区域能源供应系统评价研究

通过分析区域能源供应系统综合性能评价影响因素,设计系统评价指标体系,运用层次分析法(AHP)和熵权法结合的组合赋权法确定指标权重,构建加权灰色关联决策矩阵,最终提出了一种基于组合赋权和灰色关联投影法的区域能源供应系统方案优选方法.运用灰色关联投影值对备选方案进行优劣排序,案例分析表明该模型具有程序化、科学实用、便于操作等特点,具有推广和应用价值.     

Projection pressure and Bowen’s equation for a class of self-similar fractals with overlap structure

Let {Si}il=1 be an iterated function system (IFS) on Rd with attractor K. Let π be the canonical projection. In this paper, we define a new concept called "projection pressure" Pπ(φ) for ∈ C(Rd) under certain affine IFS, and show the variational principle about the projection pressure. Furthermore, we check that the unique zero root of "projection pressure" still satisfies Bowen’s equation when each Si is the similar map with the same compression ratio. Using the root of Bowen’s equation, we can get the Hausdorff dimension of the attractor K.     

零化多项式的一个应用

利用矩阵的零化多项式 ,给出计算标准基解矩阵 e At的一个公式 .利用向量关于矩阵的零化多项式 ,给出常系数齐次线性微分方程组初值问题的一个求解公式 .相应地 ,可以推出常系数齐次线性差分方程组在给定的初始条件下的一个求解公式 .     

A Carleman Function and the Cauchy Problem for the Laplace Equation

We suggest an explicit formula for reconstruction of a harmonic function in a domain from its values and the values of its normal derivative on part of the boundary; i.e., we give an explicit continuation formula and a regularization procedure for a solution to the Cauchy problem for the Laplace equation.     

Stochastic Volterra equations driven by fractional Brownian motion

This paper is devoted to study a class of stochastic Volterra equations driven by fractional Brownian motion. We first prove the Driver type integration by parts formula and the shift Harnack type inequalities. As a direct application, we provide an alternative method to describe the regularities of the law of the solution. Secondly, by using the Malliavin calculus, the Bismut type derivative formula is established, which is then applied to the study of the gradient estimate and the strong Feller property. Finally, we establish the Talagrand type transportation cost inequalities for the law of the solution on the path space with respect to both the uniform metric and the L₂-metric.