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一般区域上凹方程的Dirichlet问题(英文)
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作者 保继光 胡云娇 《北京师范大学学报(自然科学版)》 CAS CSCD 北大核心 2000年第6期729-734,共6页
在完全非线性情形 ,构造了一个关键的函数u0 ,获得了上确界的先验估计 。
关键词 凹方程 上确界估计 椭圆方程 函数uo
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序Banach空间中单调的凹算子方程正解的存在性
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作者 梁本中 《信阳师范学院学报(自然科学版)》 CAS 1989年第3期199-205,共7页
本文给出了:依赖于参数的,单调的,凹算子方程正解的存在性定理及单调的,u_o——凹算子方程正解的存在与唯一性定理。 D——半连续在本文起基本的作用。
关键词 算子方程 u0算子方程 D—半连续 正解
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复数解题的常用技巧
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作者 陆胜潮 《中学数学教学》 1995年第S1期137-138,共2页
复数是高中数学中涉及面广,知识跨度大的内容,它具有综合代数、三角、几何为一体的特点。是研究图形变换和求轨迹的有力工具,应用十分广泛。要学好复数,除要理解复数有关概念外,还要熟练地掌握出复数解题的常用技巧。 1.利用i的性质 ... 复数是高中数学中涉及面广,知识跨度大的内容,它具有综合代数、三角、几何为一体的特点。是研究图形变换和求轨迹的有力工具,应用十分广泛。要学好复数,除要理解复数有关概念外,还要熟练地掌握出复数解题的常用技巧。 1.利用i的性质 常用下列代换:1=-i<sup>2</sup>=i<sup>4</sup>,(1±i)<sup>2</sup>=±2i, (1±i)<sup>4</sup>=-4,1/i=-i,(1+i)/(1-i)=i及b+ai=i(a-bi)=-i(-a+bi)等。 例1 计算[(5<sup>1/2</sup>+(5i)<sup>1/2</sup>)<sup>2</sup>(3-4i)]/(4+3i) 解 原式=[5 5<sup>1/2</sup>(1+i)<sup>2</sup>(-i)(4+3i)]/(4+3i) =-5(5i)<sup>1/2</sup>(2i)(1+i)=10 5<sup>1/2</sup>+10(5i)<sup>1/2</sup>. 展开更多
关键词 复数解 复数辐角 图形变换 常用技巧 高中数学 轨迹方程 除运算 二项式展开 最大值 凹方程
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On the Cauchy Problem for a Class of Nonlinear Wave Equations with Damping Term 被引量:2
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作者 SONGChang-ming KONGDe-xing 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2005年第2期111-120,共10页
The paper concerns with the existence, uniqueness and nonexistence of global solution to the Cauchy problem for a class of nonlinear wave equations with damping term. It proves that under suitable assumptions on nonli... The paper concerns with the existence, uniqueness and nonexistence of global solution to the Cauchy problem for a class of nonlinear wave equations with damping term. It proves that under suitable assumptions on nonlinear the function and initial data the abovementioned problem admits a unique global solution by Fourier transform method. The sufficient conditions of nonexistence of the global solution to the above-mentioned problem are given by the concavity method. 展开更多
关键词 nonlinear wave equation Cauchy problem global solution concavity method
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Concave Minimization for Sparse Solutions of Absolute Value Equations 被引量:5
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作者 刘晓红 樊婕 李文娟 《Transactions of Tianjin University》 EI CAS 2016年第1期89-94,共6页
Based on concave function, the problem of finding the sparse solution of absolute value equations is relaxed to a concave programming, and its corresponding algorithm is proposed, whose main part is solving a series o... Based on concave function, the problem of finding the sparse solution of absolute value equations is relaxed to a concave programming, and its corresponding algorithm is proposed, whose main part is solving a series of linear programming. It is proved that a sparse solution can be found under the assumption that the connected matrixes have range space property(RSP). Numerical experiments are also conducted to verify the efficiency of the proposed algorithm. 展开更多
关键词 absolute value equations concave minimization SPARSITY linear programming range space property
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Adaptive Finite Element Method Based on Optimal Error Estimtes for Linear Elliptic Problems on Concave Corner Domains (continuation)
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作者 汤雁 郑璇 《Journal of Mathematical Research and Exposition》 CSCD 北大核心 2004年第2期273-279,共7页
This paper is the third part in a series of papers on adaptive finite elementmethods based on optimal error estimates for linear elliptic problems on the concavecorner domains. In this paper, a result is obtained. The... This paper is the third part in a series of papers on adaptive finite elementmethods based on optimal error estimates for linear elliptic problems on the concavecorner domains. In this paper, a result is obtained. The algorithms for error controlboth in the energy norm and in the maximum norm presented in part 1 and part 2 ofthis series arc based on this result. 展开更多
关键词 adaptive finite element method concave corner domain elliptic problems
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Curvature estimates for the level sets of spatial quasiconcave solutions to a class of parabolic equations 被引量:6
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作者 CHEN ChuanQiang SHI ShuJun 《Science China Mathematics》 SCIE 2011年第10期2063-2080,共18页
We prove a constant rank theorem for the second fundamental form of the spatial convex level surfaces of solutions to equations ut = F(▽2u,▽u,u,t) under a structural condition,and give a geometric lower bound of the... We prove a constant rank theorem for the second fundamental form of the spatial convex level surfaces of solutions to equations ut = F(▽2u,▽u,u,t) under a structural condition,and give a geometric lower bound of the principal curvature of the spatial level surfaces. 展开更多
关键词 curvature estimates level sets constant rank theorem spatial quasiconcave solutions
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