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PERIODIC SYSTEMS WITH TIME DEPENDENT MAXIMAL MONOTONE OPERATORS
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作者 zhenhai liu Nikolaos S.PAPAGEORGIOU 《Acta Mathematica Scientia》 SCIE CSCD 2024年第4期1280-1300,共21页
We consider a first order periodic system in R^(N),involving a time dependent maximal monotone operator which need not have a full domain and a multivalued perturbation.We prove the existence theorems for both the con... We consider a first order periodic system in R^(N),involving a time dependent maximal monotone operator which need not have a full domain and a multivalued perturbation.We prove the existence theorems for both the convex and nonconvex problems.We also show the existence of extremal periodic solutions and provide a strong relaxation theorem.Finally,we provide an application to nonlinear periodic control systems. 展开更多
关键词 periodic boundary condition time-dependent maximal monotone operator convex and nonconvex problems extremal solutions strong relaxation
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EXISTENCE AND CONTROLLABILITY FOR NONLINEAR FRACTIONAL CONTROL SYSTEMS WITH DAMPING IN HILBERT SPACES 被引量:4
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作者 Xiuwen LI zhenhai liu +1 位作者 Jing LI Chris TISDELL 《Acta Mathematica Scientia》 SCIE CSCD 2019年第1期229-242,共14页
In this paper, we are concerned with the existence of mild solution and controllability for a class of nonlinear fractional control systems with damping in Hilbert spaces.Our first step is to give the representation o... In this paper, we are concerned with the existence of mild solution and controllability for a class of nonlinear fractional control systems with damping in Hilbert spaces.Our first step is to give the representation of mild solution for this control system by utilizing the general method of Laplace transform and the theory of(α, γ)-regularized families of operators. Next, we study the solvability and controllability of nonlinear fractional control systems with damping under some suitable sufficient conditions. Finally, two examples are given to illustrate the theory. 展开更多
关键词 EXISTENCE controllability fractional control systems DAMPING REGULARIZED RESOLVENT family
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SINGULAR DOUBLE PHASE EQUATIONS
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作者 刘振海 Nikolaos S.PAPAGEORGIOU 《Acta Mathematica Scientia》 SCIE CSCD 2023年第3期1031-1044,共14页
We study a double phase Dirichlet problem with a reaction that has a parametric singular term. Using the Nehari manifold method, we show that for all small values of the parameter, the problem has at least two positiv... We study a double phase Dirichlet problem with a reaction that has a parametric singular term. Using the Nehari manifold method, we show that for all small values of the parameter, the problem has at least two positive, energy minimizing solutions. 展开更多
关键词 double phase singular term unbalanced growth Musielak-Orlice spaces Nehari manifold positive solutions
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ANISOTROPIC(p,q)-EQUATIONS WITH COMPETITION PHENOMENA
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作者 zhenhai liu Nikolaos S.PAPAGEORGIOU 《Acta Mathematica Scientia》 SCIE CSCD 2022年第1期299-322,共24页
We consider a nonlinear Robin problem driven by the anisotropic(p,q)-Laplacian and with a reaction exhibiting the competing effects of a parametric sublinear(concave) term and of a superlinear(convex) term.We prove a ... We consider a nonlinear Robin problem driven by the anisotropic(p,q)-Laplacian and with a reaction exhibiting the competing effects of a parametric sublinear(concave) term and of a superlinear(convex) term.We prove a bifurcation-type theorem describing the changes in the set of positive solutions as the parameter varies.We also prove the existence of a minimal positive solution and determine the monotonicity and continuity properties of the minimal solution map. 展开更多
关键词 concave-convex nonlinearities anisotropic operators regularity theory maximum principle minimal positive solution
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燃料棒接触问题的新型自适应预处理方法
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作者 刘威震 刘振海 +2 位作者 辛勇 叶舒愉 张世全 《计算物理》 CSCD 北大核心 2024年第5期596-606,共11页
通过分析接触前后雅可比矩阵的稀疏结构,构造基于接触压力判断准则的新型自适应预处理方法。在接触压力为零时使用完全的雅可比矩阵作为Preconditioned Jacobian-free Newton-Krylov(PJFNK)方法的预处理矩阵,在接触压力非零时使用雅可... 通过分析接触前后雅可比矩阵的稀疏结构,构造基于接触压力判断准则的新型自适应预处理方法。在接触压力为零时使用完全的雅可比矩阵作为Preconditioned Jacobian-free Newton-Krylov(PJFNK)方法的预处理矩阵,在接触压力非零时使用雅可比矩阵的块对角作为预处理矩阵。数值试验表明:本文的自适应预处理方法能够有效提升模拟效率,求解总时间与Multiphysics Object-Oriented Simulation Environment(MOOSE)中现有方法相比减少了15.2%~33.1%。 展开更多
关键词 MOOSE PJFNK 燃料棒 力学接触 自适应预处理
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由拟线性反应扩散方程所驱动的非静态不可压缩Navier-Stokes系统
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作者 曾生达 Stanislaw Migdrski 刘振海 《中国科学:数学》 CSCD 北大核心 2022年第3期331-354,共24页
本文考虑一类由非单调多值边界条件的非静态不可压缩Navier-Stokes方程和Neumann边界条件的广义拟线性反应扩散方程所构成的新动力系统,该系统可形式化为非线性抛物方程和发展型H半变分不等式所组成的耦合系统.为获得全局弱解存在性,首... 本文考虑一类由非单调多值边界条件的非静态不可压缩Navier-Stokes方程和Neumann边界条件的广义拟线性反应扩散方程所构成的新动力系统,该系统可形式化为非线性抛物方程和发展型H半变分不等式所组成的耦合系统.为获得全局弱解存在性,首先,运用后向Euler法与反馈迭代技术引进耦合系统的时间半离散逼近问题;而后,沿用弱-弱上半连续集值算子的满射定理证明逼近问题解的存在性和先验估计;最后,采用极限过程建立系统全局弱解的存在性定理. 展开更多
关键词 非静态不可压缩Navier-Stokes方程 H半变分不等式 Clarke次梯度 半群 反应扩散方程 半离散逼近系统 满射性
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Inverse Coefficient Problems for Elliptic Hemivariational Inequalities
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作者 Cui'e XIAO zhenhai liu 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2010年第4期473-480,共8页
This paper is devoted to a class of inverse coefficient problems for nonlinear elliptic hemivariational inequalities. The unknown coefficient of elliptic hemivariational inequalities depends on the gradient of the sol... This paper is devoted to a class of inverse coefficient problems for nonlinear elliptic hemivariational inequalities. The unknown coefficient of elliptic hemivariational inequalities depends on the gradient of the solution and belongs to a set of admissible coefficients. It is shown that the nonlinear elliptic hemivariational inequalities are uniquely solvable for the given class of coefficients. The result of existence of quasisolutions of the inverse problems is obtained. 展开更多
关键词 Elliptic hemivariational inequality Inverse coefficient problem Existence of quasisolution
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