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NEW STRUCTURES FOR NON-SELFSIMILAR SOLUTIONS OF MULTI-DIMENSIONAL CONSERVATION LAWS 被引量:4
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作者 杨小舟 魏涛 《Acta Mathematica Scientia》 SCIE CSCD 2009年第5期1182-1202,共21页
In this article, we get non-selfsimilar elementary waves of the conservation laws in another kind of view, which is different from the usual self-similar transformation. The solution has different global structure. Th... In this article, we get non-selfsimilar elementary waves of the conservation laws in another kind of view, which is different from the usual self-similar transformation. The solution has different global structure. This article is divided into three parts. The first part is introduction. In the second part, we discuss non-selfsimilar elementary waves and their interactions of a class of twodimensional conservation laws. In this case, we consider the case that the initial discontinuity is parabola with u+ 〉 0, while explicit non-selfsirnilar rarefaction wave can be obtained. In the second part, we consider the solution structure of case u+ 〈 0. The new solution structures are obtained by the interactions between different elementary waves, and will continue to interact with other states. Global solutions would be very different from the situation of one dimension. 展开更多
关键词 non-selfsimilar shock wave rarefaction wave ENVELOPE multi-dimensional conservation laws
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Global Solutions and Interactions of Non-selfsimilar Elementary Waves for n-D Non-homogeneous Burgers Equation
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作者 Yuan-an ZHAO Gao-wei CAO Xiao-zhou YANG 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2023年第4期830-853,共24页
We investigate the global structures of the non-selfsimilar solutions for n-dimensional(n-D) nonhomogeneous Burgers equation, in which the initial data has two different constant states, which are separated by a(n-1)-... We investigate the global structures of the non-selfsimilar solutions for n-dimensional(n-D) nonhomogeneous Burgers equation, in which the initial data has two different constant states, which are separated by a(n-1)-dimensional sphere. We first obtain the expressions of n-D shock waves and rarefaction waves emitting from the initial discontinuity. Then, by estimating the new kind of interactions of the related elementary waves,we obtain the global structures of the non-selfsimilar solutions, in which ingenious techniques are proposed to construct the n-D shock waves. The asymptotic behaviors with geometric structures are also proved. 展开更多
关键词 non-homogeneous burgers equation n-dimensional Riemann problem global singular structure non-selfsimilar solution interactions of elementary waves
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Non-selfsimilar Global Solutions and Their Structure for the Multi-dimensional Combustion Models
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作者 Kai HU Gao-wei CAO Xiao-zhou YANG 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2017年第3期659-678,共20页
We investigate the Chapman-Jouguet model in multi-dimensional space, and construct explicitly its non-selfsimilar Riemann solutions. By the method we apply in this paper, general initial discontinuities can be dealt w... We investigate the Chapman-Jouguet model in multi-dimensional space, and construct explicitly its non-selfsimilar Riemann solutions. By the method we apply in this paper, general initial discontinuities can be dealt with, even for complex interaction of combustion waves. Furthermore, we analyze the way in which the area of unburnt gas shrinks. 展开更多
关键词 chapman-Jouguet model multi-dimensional Riemann problem non-selfsimilar solutions charac-teristic analysis
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The Singular Structure of Non-selfsimilar Global Solutions of n Dimensional Burgers Equation 被引量:6
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作者 Xiao-zhou Yang 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2005年第3期505-518,共14页
我们为 n 调查单个结构维的 non-selfsimilarglobal 解决方案和 non-selfsimilar 的相互作用 n 的基本波浪维的 Burgersequation 在起始的断绝是 n 的地方,维的光滑的表面和起始的数据就包含二个不同经常的状态,全球解决方案和一些新... 我们为 n 调查单个结构维的 non-selfsimilarglobal 解决方案和 non-selfsimilar 的相互作用 n 的基本波浪维的 Burgersequation 在起始的断绝是 n 的地方,维的光滑的表面和起始的数据就包含二个不同经常的状态,全球解决方案和一些新现象被发现。Anelegant 技术被建议构造 n 没有维的减小或并列转变的维的冲击波。 展开更多
关键词 BURGERS方程 非自相似性 球形解 初始波
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Envelope Method and More General New Global Structures of Solutions for Multi-dimensional Conservation Law
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作者 Gui-Qin Qiu Gao-Wei Cao +1 位作者 Xiao-Zhou Yang Yuan-An Zhao 《Communications on Applied Mathematics and Computation》 2023年第3期1180-1234,共55页
For the two-dimensional(2D)scalar conservation law,when the initial data contain two different constant states and the initial discontinuous curve is a general curve,then complex structures of wave interactions will b... For the two-dimensional(2D)scalar conservation law,when the initial data contain two different constant states and the initial discontinuous curve is a general curve,then complex structures of wave interactions will be generated.In this paper,by proposing and investigating the plus envelope,the minus envelope,and the mixed envelope of 2D non-selfsimilar rarefaction wave surfaces,we obtain and the prove the new structures and classifications of interactions between the 2D non-selfsimilar shock wave and the rarefaction wave.For the cases of the plus envelope and the minus envelope,we get and prove the necessary and sufficient criterion to judge these two envelopes and correspondingly get more general new structures of 2D solutions. 展开更多
关键词 Riemann problem non-selfsimilar shock wave non-selfsimilar rarefaction wave ENVELOPE Multi-dimensional conservation law
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The Non-selfsimilar Riemann Problem for 2-D Zero-Pressure Flow in Gas Dynamics 被引量:4
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作者 Wenhua SUN Wancheng SHENG 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2007年第6期701-708,共8页
为在有一条凸的曲线分开的二个经常的状态的煤气的动力学的二维的零压力的流动的 non-selfsimilar Riemann 问题被考虑。借助于概括 Rankine-Hugoniot 关系;概括典型分析方法,包含三角洲冲击波的全球答案;真空被构造。一种特殊情况... 为在有一条凸的曲线分开的二个经常的状态的煤气的动力学的二维的零压力的流动的 non-selfsimilar Riemann 问题被考虑。借助于概括 Rankine-Hugoniot 关系;概括典型分析方法,包含三角洲冲击波的全球答案;真空被构造。一种特殊情况的明确的解决方案也被给。 展开更多
关键词 黎曼 气体动力学 熵条件 三角形
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基于非局部相似和低秩矩阵逼近的SAR图像去噪 被引量:2
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作者 赵杰 王配配 门国尊 《计算机科学》 CSCD 北大核心 2017年第S1期183-187,共5页
针对合成孔径雷达图像(Synthetic Aperture Radar,SAR)受斑点噪声影响的问题,提出了一种改进的基于非局部相似和低秩矩阵逼近的SAR图像去噪方法。首先对SAR图像进行对数变换,将图像的相干乘性噪声转化为加性噪声,然后预估计图像的全局... 针对合成孔径雷达图像(Synthetic Aperture Radar,SAR)受斑点噪声影响的问题,提出了一种改进的基于非局部相似和低秩矩阵逼近的SAR图像去噪方法。首先对SAR图像进行对数变换,将图像的相干乘性噪声转化为加性噪声,然后预估计图像的全局噪声方差,利用非局部相似性引入一种新的基于欧氏距离和判定系数的联合块匹配方式,在低秩模型下采用改进残余噪声方差估计的加权核范数最小化算法(Weighted Nuclear Norm Minimization,WNNM)逼近低秩矩阵,最终实现SAR图像的噪声抑制。实验结果表明,该方法不仅使得峰值信噪比等客观指标有了明显的改善,而且更好地保存了图像的局部结构,并实现了良好的主观视觉效果。 展开更多
关键词 SAR图像去噪 联合块匹配 非局部相似性 加权核范数最小化
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非线性变换和守恒律方程的非自相似解
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作者 杨小舟 《数学物理学报(A辑)》 CSCD 北大核心 2005年第4期584-592,共9页
该文提出了一种非线性变换把一类n维单守恒律方程和初值同时降维为一维,得到非自相似形式的全局解和基本波的表达式,并发现了非自相似解和相似解之间的本质性差别和联系.
关键词 非自相似解 高维守恒律方程 激波 稀疏波
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面向对象方法学的分形论诠释
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作者 王雪 肖人彬 罗云峰 《大自然探索》 1994年第4期108-112,共5页
本文将面向对象方法学的基本内容概括为四大机制。在对分形论的简要介绍的基础上,运用该理论的观点剖析了面向对象方法学的基本思想和实现机制,指出了两者之间存在的的深刻联系,从而为面向对象的程序设计方法奠定了理论基础,并为其... 本文将面向对象方法学的基本内容概括为四大机制。在对分形论的简要介绍的基础上,运用该理论的观点剖析了面向对象方法学的基本思想和实现机制,指出了两者之间存在的的深刻联系,从而为面向对象的程序设计方法奠定了理论基础,并为其今后的发展开辟了新的思路。 展开更多
关键词 面向对象方法学 分形论 分形元
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非齐次二维Burgers方程的非自相似黎曼解的奇性结构
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作者 赵远安 曹高伟 杨小舟 《数学物理学报(A辑)》 CSCD 北大核心 2022年第4期1122-1149,共28页
该文研究了二维非齐次Burgers方程Riemann问题的激波解和稀疏波解之间相互作用的全局奇性结构及其演化,其中初值被两个相离的圆隔开并分成三片常数.首先得到了由初值间断发出的激波解和稀疏波解的表达式;其次,讨论了这些激波和稀疏波的... 该文研究了二维非齐次Burgers方程Riemann问题的激波解和稀疏波解之间相互作用的全局奇性结构及其演化,其中初值被两个相离的圆隔开并分成三片常数.首先得到了由初值间断发出的激波解和稀疏波解的表达式;其次,讨论了这些激波和稀疏波的相互作用,并发现了一些新现象,其与齐次情形相比,激波和稀疏波能一直相互作用,相互作用的时间没有使得结构发生改变的临界值;最后构造了非自相似解的全局结构,并发现了有别于齐次情形的渐近行为,即基本波区域的直径是有界的. 展开更多
关键词 非齐次Burgers方程 RIEMANN问题 全局奇性结构 非自相似解
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Envelope and Classification of Global Structures of Solutions for a Class of Two-dimensional Conservation Laws
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作者 Gao-wei CAO Kai HU Xiao-zhou YANG 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2016年第3期579-590,共12页
Two-dimensional Riemann problem for scalar conservation law are investigated and classification of global structure for its nomselfsimilar solution is given by analysis of structure and classification of envelope for ... Two-dimensional Riemann problem for scalar conservation law are investigated and classification of global structure for its nomselfsimilar solution is given by analysis of structure and classification of envelope for non-selfsimilar 2D rarefaction wave. Initial data has two different constant states which are separated by initial discontinuity. We propose the concepts of plus envelope, minus envelope and mixed envelope, and some new structures and evolution phenomena are discovered by use of these concepts. 展开更多
关键词 shock wave rarefaction wave cylinder face ENVELOPE non-selfsimilar solution
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