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一类Neumann方程正解的存在性 被引量:1
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作者 彭双阶 《孝感师专学报》 1999年第4期15-18,共4页
本文讨论了下面的Neumann边值问题这里Ω是RN的有界光滑区域,Ω是C1类的,证明了在f(x,u)、g(x,u)满足一定的条件下该方程正解的存在性。
关键词 neumann方程 存在性 Neumnn边值问题 山路引理 正解 椭圆方程
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凸形多面体个体晶粒的三维von Neumann准确方程 被引量:3
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作者 王浩 刘国权 《金属学报》 SCIE EI CAS CSCD 北大核心 2008年第11期1332-1334,共3页
由晶粒长大过程的曲率驱动本质出发,以不同于MacPherson和Srolovitz的方法,推导出凸型多面体晶粒的三维von Neumann关系式,无任何其他形状假设及晶粒尺寸分布或拓扑分布要求.在应用于凸型多面体晶粒时,本文结果与MacPherson和Srolovitz... 由晶粒长大过程的曲率驱动本质出发,以不同于MacPherson和Srolovitz的方法,推导出凸型多面体晶粒的三维von Neumann关系式,无任何其他形状假设及晶粒尺寸分布或拓扑分布要求.在应用于凸型多面体晶粒时,本文结果与MacPherson和Srolovitz给出的结果完全一致.对于凸型多面体晶粒,三维个体晶粒长大速率是晶粒平均切直径和晶粒棱总长度的函数,符合Kinderlehrer指出的n维体积的变化速率仅与胞的(n-2)维特征量有关的规律. 展开更多
关键词 三维晶粒长大 von neumann方程 曲率 平均切直径
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凸形晶粒的各向异性三维von Neumann方程研究
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作者 王浩 刘国权 栾军华 《物理学报》 SCIE EI CAS CSCD 北大核心 2012年第4期479-482,共4页
三维晶粒长大规律是材料科学研究的核心问题之一,本文通过考虑实际多晶组织中晶界能和晶界迁移率的不均匀性和各向异性因素对晶粒三晶棱处两面角大小的影响,借助经典体视学中晶粒界面积分平均曲率与平均切直径的关系,经推导得到了适合... 三维晶粒长大规律是材料科学研究的核心问题之一,本文通过考虑实际多晶组织中晶界能和晶界迁移率的不均匀性和各向异性因素对晶粒三晶棱处两面角大小的影响,借助经典体视学中晶粒界面积分平均曲率与平均切直径的关系,经推导得到了适合于凸形晶粒的一般性三维von Neumann方程,结果表明实际凸形晶粒的准确长大速率可以表示为晶粒的平均切直径、三晶棱总长度和三晶棱处两面角的函数.所得方程经过了Kelvin十四面体和5种规则多面体验证,对于三维von Neumann方程(Nature,2007,446:1053)进一步推广并应用于实际金属和陶瓷材料具有重要的意义. 展开更多
关键词 三维晶粒长大 各向异性 von neumann方程 平均切直径
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在再生核空间中求解一类二阶非线性Neumann问题 被引量:2
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作者 王洋 么焕民 《哈尔滨师范大学自然科学学报》 CAS 2009年第6期13-16,共4页
运用迭代算法在再生核空间W3[0,1]中求解一类二阶非线性Neu-mann问题.给出了精确解的级数形式的精确表达式,证明了近似解un(x)一致收敛于精确解w(x).数值算例验证了方法是高精度的和有效的.
关键词 neumann方程 再生核空间 迭代序列 精确解
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Quantum Entanglement of Parallel-Coupled Double Quantum Dots:a Theoretical Study Using the Hierarchical Equations of Motion Approach
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作者 HongGong ArifUIlah +2 位作者 LvZhouYe XiaoZheng YiJingYan 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2018年第4期510-516,615,共8页
Quantum dots comprise a type of quantum impurity system. The entanglement and co- herence of quantum states are significantly influenced by the strong electron-electron interactions among impurities and their dissipat... Quantum dots comprise a type of quantum impurity system. The entanglement and co- herence of quantum states are significantly influenced by the strong electron-electron interactions among impurities and their dissipative coupling with the surrounding environment. Competition between many-body effects and transfer couplings plays an important role in determining the entanglement among localized impurity spins. In this work, we employ the hierarchical-equations-of-rnotion approach to explore the entanglement of a strongly correlated double quantum dots system. The relation between the total system entropy and those of subsystems is also investigated. 展开更多
关键词 Double quantum dots Quantum entanglement Renyi entropy von Neurnann entropy CONCURRENCE Hierarchical-equations-of-rnotion method
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Existence of Positive Solutions to Second Order Neumann Boundary Value Problems 被引量:31
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作者 蒋达清 刘辉昭 《Journal of Mathematical Research and Exposition》 CSCD 2000年第3期360-364,共5页
The existence of positive solutions to second-order Neumann BVPs -u' + Mu = f(t, u), u'(0) = u'(1) = 0 and u' + Mu = f(t, u), u'(0) =u'(1) is proved by a simple application of a Fixed Poin... The existence of positive solutions to second-order Neumann BVPs -u' + Mu = f(t, u), u'(0) = u'(1) = 0 and u' + Mu = f(t, u), u'(0) =u'(1) is proved by a simple application of a Fixed Point Theorem in cones due to Krasnoselskii[1,6]. 展开更多
关键词 neumann BVP positive solutions the fixed point theorem.
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Exact Boundary Synchronization for a Coupled System of Wave Equations with Neumann Boundary Controls 被引量:5
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作者 Tatsien LI Xing LU Bopeng RAO 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2018年第2期233-252,共20页
In this paper, for a coupled system of wave equations with iNeumann boundary controls, the exact boundary synchronization is taken into consideration. Results are then extended to the case of synchronization by groups... In this paper, for a coupled system of wave equations with iNeumann boundary controls, the exact boundary synchronization is taken into consideration. Results are then extended to the case of synchronization by groups. Moreover, the determination of the state of synchronization by groups is discussed with details for the synchronization and for the synchronization by 3-groups, respectively. 展开更多
关键词 Exact boundary synchronization Exact boundary synchronization bygroups State of synchronization State of synchronization by groups Coupled system of wave equations neumann boundary control
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Singularly perturbed Neumann problem for fractional Schrdinger equations
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作者 Guoyuan Chen 《Science China Mathematics》 SCIE CSCD 2018年第4期695-708,共14页
This paper is concerned with a Neumann type problem for singularly perturbed fractional nonlinear Schrdinger equations with subcritical exponent. For some smooth bounded domain ? R^n, our boundary condition is given... This paper is concerned with a Neumann type problem for singularly perturbed fractional nonlinear Schrdinger equations with subcritical exponent. For some smooth bounded domain ? R^n, our boundary condition is given by∫_?u(x)-u(y)/|x-y|^(n+2s)dy = 0 for x ∈ R^n\?.We establish existence of non-negative small energy solutions, and also investigate the integrability of the solutions on Rn. 展开更多
关键词 neumann problem nonlinear fractional Schrdinger equations singular perturbation fractional Laplacian
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Quantitative conditions for time evolution in terms of the von Neumann equation
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作者 WenHua Wang HuaiXin Cao +1 位作者 ZhengLi Chen Lie Wang 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2018年第7期54-60,共7页
The adiabatic theorem describes the time evolution of the pure state and gives an adiabatic approximate solution to the Schrrdinger equation by choosing a single eigenstate of the Hamiltonian as the initial state. In ... The adiabatic theorem describes the time evolution of the pure state and gives an adiabatic approximate solution to the Schrrdinger equation by choosing a single eigenstate of the Hamiltonian as the initial state. In quantum systems, states are divided into pure states (unite vectors) and mixed states (density matrices, i.e., positive operators with trace one). Accordingly, mixed states have their own corresponding time evolution, which is described by the von Neumann equation. In this paper, we discuss the quantitative conditions for the time evolution of mixed states in terms of the von Neumann equation. First, we introduce the definitions for uniformly slowly evolving and δ-uniformly slowly evolving with respect to mixed states, then we present a necessary and sufficient condition for the Hamiltonian of the system to be uniformly slowly evolving and we obtain some upper bounds for the adiabatic approximate error. Lastly, we illustrate our results in an example. 展开更多
关键词 quantitative condition time evolution uniformly slowly evolving δ-uniformly slowly evolving upper bound
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两种三维晶粒长大理论模型的比较 被引量:2
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作者 王耀华 王浩 刘国权 《金属热处理》 CAS CSCD 北大核心 2016年第9期171-173,共3页
对两种具有代表性的晶粒长大速率模型,三维von Neumann方程和三维Hillert方程进行了比较研究,分析了两理论模型之间的异同及内在联系。结果表明:二者分别是基于晶界的积分平均曲率和平均平均曲率的曲率驱动长大速率模型;结合三维晶粒的... 对两种具有代表性的晶粒长大速率模型,三维von Neumann方程和三维Hillert方程进行了比较研究,分析了两理论模型之间的异同及内在联系。结果表明:二者分别是基于晶界的积分平均曲率和平均平均曲率的曲率驱动长大速率模型;结合三维晶粒的拓扑-尺寸抛物线统计关系,三维von Neumann方程可以转化为Hillert方程;两种速率理论模型分别从个体角度和分组统计平均角度阐述了三维晶粒长大动力学。 展开更多
关键词 三维晶粒长大理论模型 von neumann方程 Hillert方程 积分平均曲率 平均平均曲率
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REGULARITY THEORY FOR SYSTEMS OFPARTIAL DIFFERENTIAL EQUATIONS WITHNEUMANN BOUNDARY CONDITIONS
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作者 A.BENSOUSSAN J.FREHSE 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2002年第2期165-180,共16页
The objective of this paper is to consider the theory of regularity of systems of partial differential equations with Neumann boundary conditions. It complements previous works of the authors for the Dirichlet case. T... The objective of this paper is to consider the theory of regularity of systems of partial differential equations with Neumann boundary conditions. It complements previous works of the authors for the Dirichlet case. This type of problem is motivated by stochastic differential games. The Neumann case corresponds to stochastic differential equations with reflection on boundary of the domain. 展开更多
关键词 Regularity theory neumann boundary conditions Dirichlet problem
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Optimal Conditions on Generalized Solutions of Coupled Nonlinear Diffusion Systems
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作者 李锋杰 刘丙辰 郑斯宁 《Journal of Mathematical Research and Exposition》 CSCD 2009年第6期954-960,共7页
This paper studies coupled nonlinear diffusion equations with more general nonlinearities, subject to homogeneous Neumann boundary conditions. The necessary and sufficient conditions are obtained for the existence of ... This paper studies coupled nonlinear diffusion equations with more general nonlinearities, subject to homogeneous Neumann boundary conditions. The necessary and sufficient conditions are obtained for the existence of generalized solutions of the system, which extend the known results for nonlinear diffusion systems with more special nonlinearities. 展开更多
关键词 nonlinear diffusion equations generalized solution classical solution.
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