THE MEAN VALUE THEOREM AND CONVERSE THEOREM OF ONE CLASS THE FOURTH-ORDER PARTIAL DIFFERENTIAL EQUATIONS

For the formal presentation about the definite problems of ultra-hyperbolic equations, the famous Asgeirsson mean value theorem has answered that Cauchy problems are ill-posed to ultra-hyperbolic partial differential equations of the second-order. So it is important to develop Asgeirsson mean value theorem. The mean value of solution for the higher order equation hay been discussed primarily and has no exact result at present. The mean value theorem for the higher order equation can be deduced and satisfied generalized biaxial symmetry potential equation by using the result of Asgeirsson mean value theorem and the properties of derivation and integration. Moreover, the mean value formula can be obtained by using the regular solutions of potential equation and the special properties of Jacobi polynomials. Its converse theorem is also proved. The obtained results make it possible to discuss on continuation of the solutions and well posed problem.

A Note on the Mean Value Theorems

The mean value theorem for derivatives says that for a given function over a closed and bounded interval, there is a point P on the graph such that the tangent at P is parallel to the secant through the two endpoints. The mean value theorem for definite integrals says that the area under the function is equal to the area of a rectangle whose base is the length of the interval and height of some point Q on the graph. These two theorems have been studied and utilized extensively and they form the backbone of many important theorems in different branches of mathematics. In this note, we pose the question: for what functions do the two points P and Q always coincide? We find that the only analytic functions satisfying this condition are linear or exponential functions.

一个新的积分第二中值定理

在加强了假设条件的基础上,得到了一个新的积分第二中值定理.与原定理相比较,新的定理具有明显的几何意义,更富有数学美感.另外,说明了不同形式的积分第二中值定理的相互等价性.

柯西中值定理的证明及其应用探索

为促进高职学生深入理解柯西中值定理的内容及应用,探索了两种证明柯西中值定理的方法,并阐释了三个中值定理之间的关系.介绍了柯西中值定理在等式证明、不等式证明、函数单调性判断及极限计算中的应用,并进一步应用柯西中值定理证明了洛必达法则、积分中值定理及泰勒定理.对柯西中值定理的证明、内涵及其在解题中的应用进行探索,为微分中值定理的学习和应用提供参考.

泰勒公式的一个教学注记

文中利用行列式作工具泰勒公式的余项有多种形式,它们在不同的应用中各有所长.本文汇总了泰勒公式常见的4种余项,并论述了它们之间的关系与特点,同时给出了余项的几个新的变式,以供教学参考.

“一轴双线三全育人”理念下高等数学课程思政探索与实践

该文以高等数学课程为载体,遵循“一轴双线三全育人”的理念,以立德树人为“主轴”,以“理论+技能”培养的知识线和“学科素养+使命担当”传承的思想线为“双线”进行运作,构建全员、全程、全课程育人格局。以高等数学课程体系里相应的知识单元为立足点,以最新的思政理念为引领,以“专业”+“思政”融合为目标,以“润物细无声”为标准,扎实推进高等数学课程承载思政的教学改革,为培养高素质创新型人才奠定坚实的基础。

Observer design for induction motor： an approach based on the mean value theorem

In this paper, observer design for an induction motor has been investigated. The peculiarity of this paper is the synthesis of a mono-Luenberger observer for highly coupled system. To transform the nonlinear error dynamics for the induction motor into the linear parametric varying （LPV） system, the differential mean value theorem combined with the sector nonlinearity transformation has been used. Stability conditions based on the Lyapunov function lead to solvability of a set of linear matrix inequalities. The proposed observer guarantees the global exponential convergence to zero of the estimation error. Finally, the simulation results are given to show the performance of the observer design.

基于换相角预测计算的高压直流输电双桥共同换相预判方法

高压直流输电系统交流故障下出现双桥共同换相会增大换相失败的风险,提前判断双桥共同换相的发生有利于及时采取措施避免换相失败。为获取对双桥共同换相进行预判所需的高精度换相角预测计算结果,利用拉格朗日中值定理建立换相角与中值时刻的关系,并构造虚拟换相过程用于确定中值时刻。仿真结果表明,所提换相角预测计算方法具有良好的鲁棒性和精度,用于双桥共同换相预判中能有效预判双桥共同换相的发生。

微分中值定理中思政元素的探讨

数学分析课程不仅传授数学知识,而且蕴含着丰富的思政元素。以微分中值定理教学为例,通过细致解读三大中值定理的核心内容,并结合实际问题中的应用,巧妙地融入哲学思想、价值观教育和科学家精神等思政元素。在教学实践中,通过将思想政治教育与数学分析教学的有机结合,旨在培养学生的数学思维品质,使其树立正确的世界观、人生观和价值观,同时激发学生对数学分析课程的学习兴趣和热情。

几类新型中值定理中值点的渐近性

研究几类新型中值定理中值点的渐近性,利用比较函数和引理,在一定条件下,建立了几类新型中值定理中值点更广泛的渐近估计式,所得结果推广和改进了有关文献中的相应结果。

基于一阶偏导数判定多元函数极值的一个充分条件

在一元函数极值充分条件的基础上,用类比的方法给出二元函数极值的一阶充分条件,并推广到多元函数,且该充分条件适用于驻点和偏导数不存在点的判断,其证明过程只涉及到拉格朗日中值定理和偏导数的计算.

A Different Version of Flett's Mean Value Theorem and an Associated Functional Equation

In this paper we present a mean value theorem derived from Flett's mean value theorem. It turns out that cubic polynomials have the midpoint of the interval as their mean value point.To answer what class of functions have this property,we consider a functional equation associated with this mean value theorem.This equation is then solved in a general setting on abelian groups.

Generation of a Problem about Mean Value Theorem

This paper presents a generalized form and its application to a problem, which was proposed by F.P. Callham.

Classical state feedback controller for nonlinear systems using mean value theorem： closed Ioop-FOC of PMSM motor application

The problem of state feedback controllers for a class of Takagi-Sugeno （T-S） Lipschitz nonlinear systems is investigated. A simple systematic and useful synthesis method is proposed based on the use of the differential mean value theorem （DMVT） and convex theory. The proposed design approach is based on the mean value theorem （MVT） to express the nonlinear error dynamics as a convex combination of known matrices with time varying coefficients as linear parameter varying （LPV） systems. Using the Lyapunov theory, stability conditions are obtained and expressed in terms of linear matrix inequalities （LMIs）. The controller gains are then obtained by solving linear matrix inequalities. The effectiveness of the proposed approach for closed loop-field oriented control （CL-FOC） of permanent magnet synchronous machine （PMSM） drives is demonstrated through an illustrative simulation for the proof of these approaches. Furthermore, an extension for controller design with parameter uncertainties and perturbation performance is discussed.

Nonlinear unknown input observer using mean value theorem and genetic algorithm

In this note,we consider a new unknown input observer design for nonlinear systems.The main idea consists in determining the estimation error and mean value theorem parameters(β)to introduce them into proposed observer structure.This process is designed on the basis of mean value theorem and genetic algorithm.The stability study relies on the use of a classical quadratic Lyapunov function.The observer’s gains are determined systematically.For the validation of theoretical development proposed in this paper,we consider two practical realizations that deals with the secure communication problem.

A Bombieri-type mean-value theorem concerning exponential sums over primes

In several classical problems in number theory,like the Goldbach problem or the twinprime problem,one has to treat the exponential

一类积分型中值定理的渐近性讨论

在适当的条件下,将Lagrange中值定理、Cauchy微分中值定理、第一积分中值定理和推广的第一积分中值定理统一起来,得到了一类积分型中值定理,并讨论它们"中间点"的渐近性,得出了相应的结论.

预测-校正EKF算法在自主导航中的应用

为提高航天器自主导航系统非线性估计精度,通过分析EKF线性化方法的缺点,基于数学分析理论研究了非线性函数线性化展开点以及雅可比矩阵取值点不同对线性化逼近程度的影响,然后对传统EKF算法的线性化展开方式进行了改进,提出了一种基于中值定理和平滑估计的预测-校正EKF(FR-EKF)新算法。仿真结果表明,该算法在精度上优于EKF算法。

截面分析法对任意凸形粒子周围界面过渡区厚度过高估计的解析解

借助于几何概率中的一些相关理论,从理论分析的角度,对表面为凸形曲线或曲面的二维和三维任意形状粒子建立了表观界面过渡区厚度统计平均值和实际界面过渡区厚度之间的定量关系。结果表明,对于二维凸形粒子,截面分析法所得的表观界面过渡区厚度的统计平均值与实际界面过渡区厚度之间的比值小于π/2。精确比值与粒子的形状有关。如果实际界面过渡区厚度与粒子的尺寸相比可以忽略的话,截面分析法所得的表观界面过渡区厚度的统计平均值与实际界面过渡区厚度之间的比值约等于π/2。对于三维凸形粒子,截面分析法所得的表观界面过渡区厚度的统计平均值与实际界面过渡区厚度之间的比值小于2,比值的精确解与粒子的形状有关。如果实际界面过渡区厚度与粒子的尺寸相比可以忽略的话,截面分析法所得的表观界面过渡区厚度的统计平均值与实际界面过渡区厚度之间的比值约等于2。

抗频散有限差分波动方程数值模拟及逆时偏移

数值频散是有限差分法求解波动方程时的最突出问题,严重降低了波场模拟的分辨率,通常使用更精细的计算网格或较长的差分算子来解决,但都会显著地增加计算成本。为此,本文构造了一种新的波动方程差分格式压制数值频散,通过在常规的差分方程中增加了频散校正项,能够有效地衰减高波数成分,抑制频散;根据相速度和群速度对频散的影响,推导了二阶和四阶差分格式频散校正项的最优参数值,当校正参数等于该值时,相应频散曲线图中相速度最接近群速度,频散误差最小。数值模拟和逆时偏移的实验结果表明:本文构造的抗频散算法对数值频散的抑制效果明显,新方法的二阶差分抗频散性能不低于常规四阶差分,而计算效率近似于常规二阶差分;抗频散差分格式与同阶常规差分格式相比,逆时偏移成像效果更好,精度更高。