共查询到20条相似文献,搜索用时 296 毫秒
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一、专题的背景与分析
1. 背景
闵行区的沪闵路─春申路口是交通特别拥挤的交叉路口之一.家住莘庄地区的同学有一个共同的感受,在他们到校或回家路上必经的沪闵路─春申路口时常遇到塞车现象.…… 相似文献
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"牛吃草"问题又称为消长问题,是17世纪英国伟大的科学家牛顿提出来的.典型牛吃草问题的条件是假设草的生长速度固定不变,不同头数的牛吃光同一片草地所需的天数各不相同,求若干头牛吃这片草地可以吃多少天.由于吃的天数不同,草又是天天在生长的,所以草的存量随吃的天数不断地变化.…… 相似文献
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2010-2011学年度武汉市部分学校新高三起点调研测试的一道试题引起了我的注意.原题如下:
在正四面体P-ABC中,M为△ABC内(含边界)一动点,且点M到三个侧面PAB,PBC,PCA的距离成等差数列,则点M的轨迹是
A.一条线段 B.椭圆的一部分
C.双曲线的一部分 D.抛物线的一部分 相似文献
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通过在动态变形网格上求解N-S方程的方法,研究了昆虫拍动翅的非定常变形对其气动力的影响.其中,拍动翅的扭转变形对气动力影响很小,拱形变形则会产生显著的影响,扭转和拱形组合变形的效果与拱形变形单独的效果基本相同.在6%拱形和20度扭转组合变形的情况下(此为对大量昆虫观察所得到的典型值),相对于无变形平板翅,升力增加了10~20%,升阻比增加了约10%.翅膀的变形可增大最大升力系数;同时,可减小飞行的能耗,例如,对于做悬停飞行的熊蜂,其翅膀的动态变形(6%拱形和20度扭转组合变形)使其飞行中的能耗比无变形情况降低了约16%. 相似文献
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导数作为大学的重要内容,进入中学数学教材后,给传统的内容注入了生机与活力,为中学数学命题的研究提供了新视角,新方法.由于导数是研究函数性质的一个很好的工具,它的用途十分广泛,它在解决函数、不等式、解析几何等问题有独到的功能.因此,近几年的高考正逐年加大对导数问题的考查力度,本文通过对07年全国各地高考题的整理和分析寻找命题规律,希望能对今后的教学提供一点复习思路.…… 相似文献
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M. G. Zavgorodnij 《Differential Equations》2014,50(4):441-452
We consider boundary value problems of arbitrary order for linear differential equations on a geometric graph. Solutions of boundary value problems are coordinated at the interior vertices of the graph and satisfy given conditions at the boundary vertices. For considered boundary value problems, we construct adjoint boundary value problems and obtain a self-adjointness criterion. We describe the structure of the solution set of homogeneous self-adjoint boundary value problems with alternating coefficients of a differential equation and obtain nondegeneracy conditions for these boundary value problems. 相似文献
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In this article we present a new fixed point theorem for a class of general mixed monotone operators, which extends the existing corresponding results. Moreover, we establish some pleasant properties of nonlinear eigenvalue problems for mixed monotone operators. Based on them the local existence-uniqueness of positive solutions for nonlinear boundary value problems which include Neumann boundary value problems, three-point boundary value problems and elliptic boundary value problems for Lane-Emden-Fowler equations is proved. The theorems for nonlinear boundary value problems obtained here are very general. 相似文献
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一类Dirichlet边值逆问题 总被引:2,自引:0,他引:2
给出解析函数的一类Dirichlet边值逆问题的数学提法.依据解析函数Dirichlet边值问题和广义Dirichlet边值问题的理论,讨论了此边值逆问题的可解性.利用解析函数Dirichlet边值问题的Schwarz公式,给出了该边值逆问题的可解条件和解的表示式. 相似文献
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Thomas Krainer 《Journal of Functional Analysis》2007,244(2):351-386
We investigate general Shapiro-Lopatinsky elliptic boundary value problems on manifolds with polycylindrical ends. This is accomplished by compactifying such a manifold to a manifold with corners of in general higher codimension, and we then deal with boundary value problems for cusp differential operators. We introduce an adapted Boutet de Monvel's calculus of pseudodifferential boundary value problems, and construct parametrices for elliptic cusp operators within this calculus. Fredholm solvability and elliptic regularity up to the boundary and up to infinity for boundary value problems on manifolds with polycylindrical ends follows. 相似文献
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We suggest a new approach to the statement of boundary value problems for elliptic partial differential equations on arbitrary Riemannian manifolds which is based on the consideration of equivalence classes of functions on a manifold. Using this approach, we establish some interrelation between the solvability of boundary value problems and solvability of exterior boundary problems for the stationary Schrodinger equation. Also we prove the comparison and uniqueness theorems for solutions to boundary value problems in this statement and obtain sufficient conditions for solvability of boundary value problems when the coefficient in the Schrodinger equation is changed. 相似文献
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一类广义解析函数的Riemann边值逆问题 总被引:8,自引:0,他引:8
本文给出了一类有关广义解析函数Riemann边值逆问题的数学提法.在将此边值逆问题转化为边值问题的基础上,借助于广义解析函数边值问题的相关理论,分别获得了此边值逆问题在正则型和非正则型情况下的解. 相似文献
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L. A. Alexeyeva 《Differential Equations》2010,46(4):515-522
We consider boundary value problems for an elastic medium bounded by a cylindrical surface on which a load with a constant-in-time
form is moving at a constant subsonic velocity. This class of problems is a model class for the dynamics of underground structures
like transport tunnels and ground transport. The method of generalized functions is developed for the solution of boundary
value problems. We construct dynamic analogs of Green formulas and use them to derive singular boundary integral equations,
which solve the considered boundary value problems. 相似文献
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This paper investigates the analytical approximate solutions of third order three-point boundary value problems using reproducing kernel method. The solution obtained by using the method takes the form of a convergent series with easily computable components. However, the reproducing kernel method can not be used directly to solve third order three-point boundary value problems, since there is no method of obtaining reproducing kernel satisfying three-point boundary conditions. This paper presents a method for solving reproducing kernel satisfying three-point boundary conditions so that reproducing kernel method can be used to solve third order three-point boundary value problems. Results of numerical examples demonstrate that the method is quite accurate and efficient for singular second order three-point boundary value problems. 相似文献
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We study subsolutions for semilinear elliptic boundary value problems in L1. We consider as well nonlinear as linear boundary conditions. The nonlinear functions may be multivated. We characterize in terms of p.d.e. the subsolutions defined by a nonlinear functional analysis argument. Applications are given to obtain existence results for semilinear elliptic boundary value problems and comparison and estimates for nonlinear parabolic boundary value problems. 相似文献
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《Applied Mathematics Letters》2005,18(8):875-879
Assuming a uniqueness assumption on the variational boundary value problems, uniqueness and existence is established for problems which generalize focal boundary value problems. 相似文献