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Journal of Computational Mathematics 2006年第2期24卷 157-168页

作者： Huo-yuan Duan qun lin LSEC ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China

This paper provides a proof for the uniform convergence rate （independently of the number of mesh levels） for the nonnested V-cycle multigrid method for nonsymmetric and indefinite second-order elliptic problems.

关键词： Nonnested V-cycle multigrid method Second-order elliptic problems.

A SUPERONVERGENCE ANALYISIS FOR FINITE ELEMENT SOLUTION BY THE INTERPOLANT POSTPROCESSING ON IRREGULAR MESHES FOR SMOOTH PROBLEM

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Journal of Computational Mathematics 2001年第3期19卷 323-326页

作者： Qi-ding Zhu qun lin Institute of Science Hunan Normal UniversityChangsha 410081China Institute of System Academy of Mathematics and Systems SciencesChinese Academy of SciencesBeijing 100080China

The post-processing procedure is given by a interpolant postprocessing of the finit element solution by appropriately-define finite dimensional subspaces, The corresponding superconvergence are established on general ... 详细信息

关键词： finite element superconvergence interpolant postprocessing

An Acceleration Method for Stationary Iterative Solution to linear System of Equations

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Advances in Applied Mathematics and Mechanics 2012年第4期4卷 473-482页

作者： qun lin Wujian Peng Academy of Math and System Sciences Chinese Academy of SciencesInstitute Computational MathematicsBeijing 100190China School of Mathematics and Information Sciences Zhaoqing UniversityZhaoqingGuangdong 526061China

An acceleration scheme based on stationary iterative methods is presented for solving linear system of *** Chebyshev semi-iterative method which requires accurate estimation of the bounds for iterative matrix eigenvalues,we use a wide range of Chebyshev-like polynomials for the accelerating process without estimating the bounds of the iterative matrix.A detailed error analysis is presented and convergence rates are *** experiments are carried out and comparisons with classical Jacobi and Chebyshev semi-iterative methods are provided.

关键词： Iterative method error analysis recurrence

Cerebral dopamine neurotrophic factor promotes the proliferation and differentiation of neural stem cells in hypoxic environments

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Neural Regeneration Research 2020年第11期15卷 2057-2062页

作者： Chao-qun lin Lu-Kui Chen School of Medicine Southeast UniversityNanjingJiangsu ProvinceChina Department of Neurosurgery Cancer CenterIntegrated Hospital of Traditional Chinese MedicineSouthern Medical UniversityGuangzhouGuangdong ProvinceChina

Previous research found that cerebral dopamine neurotrophic factor(CDNF)has a protective effect on brain dopaminergic neurons,and CDNF is regarded as a promising therapeutic agent for neurodegenerative ***,the effects of CDNF on the proliferation,differentiation,and apoptosis of neural stem cells(NSCs),which are very sensitive to hypoxic environments,remain *** this study,NSCs were extracted from the hippocampi of fetal rats and cultured with different concentrations of *** results showed that 200 nM CDNF was the optimal concentration for significantly increasing the viability of NSCs under non-hypoxic environmental ***,the cells were cultured with 200 nM CDNF under the hypoxic conditions of 90%N_2,5%CO_2,and 5%air for 6 *** results showed that CDNF significantly improved the viability of hypoxic NSCs and reduced apoptosis among hypoxic *** detection of markers showed that CDNF increased the differentiation of hypoxic NSCs into neurons and *** also reduced the expression level of lin28 protein and increased the expression of Let-7 mRNA in NSCs,under hypoxic *** conclusion,we determined that CDNF was able to reverse the adverse proliferation,differentiation,and apoptosis effects that normally affect NSCs in a hypoxic ***,the lin28/Let-7 pathway may be involved in this regulated function of *** present study was approved by the Laboratory Animal Centre of Southeast University,China(approval No.20180924006)on September 24,2018.

关键词： apoptosis astrocyte cerebral dopamine neurotrophic factor differentiation hypoxia Let-7 lin28 neural stem cells neuron proliferation

Machining distortion prediction of aerospace monolithic components

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第5期10卷 661-668页

作者： Yun-bo BI qun-lin CHENG Hui-yue DONG Ying-lin KE State Key Lab of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China Shanghai Spaceflight Precision Machinery Research Institute Shanghai 201600 China

To predict the distortion of aerospace monolithic components, a model is established to simulate the numerical control (NC) milling process using 3D finite element method (FEM). In this model, the cutting layer is simplified firstly. Then, the models of cutting force and cutting temperature are established to gain the cutting loads, which are applied to the mesh model of the part. Finally, a prototype of machining simulation environment is developed to simulate the milling process of a spar. Key factors influencing the distortion, such as initial residual stress, cutting loads, fixture layout, cutting sequence, and tool path are considered all together. The total distortion of the spar is predicted and an experiment is conducted to validate the numerical results. It is found that the maximum discrepancy between the simulation results and experiment values is 19.0%

关键词： Monolithic component Machining distortion Finite element simulation

Computing the lower and upper bounds of Laplace eigenvalue problem:by combining conforming and nonconforming finite element methods

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Science China Mathematics 2012年第5期55卷 1069-1082页

作者： LUO FuSheng lin qun XIE HeHu LSEC ICMSECAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

We introduce some ways to compute the lower and upper bounds of the Laplace eigenvalue *** using the special nonconforming finite elements,i.e.,enriched Crouzeix-Raviart element and extended Q1ro t,we get the lower bound of the ***,we use conforming finite elements to do the postprocessing to get the upper bound of the eigenvalue,which only needs to solve the corresponding source problems and a small eigenvalue problem if higher order postprocessing method is ***,we can obtain the lower and upper bounds of the eigenvalues simultaneously by solving eigenvalue problem only *** numerical results are also presented to demonstrate our theoretical analysis.

关键词： lower bound upper bound ECR EQ1ro t eigenvalue problem postprocessing

An orthogonally accumulated projection method for symmetric linear system of equations

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Science China Mathematics 2016年第7期59卷 1235-1248页

作者： PENG Wu Jian lin qun ZHANG Shu Hua Department of Mathematics and Statistics Zhaoqing University Academy of Mathematics and Systems Science Chinese Academy of Sciences Research Center for Mathematics and Economics Tianjin University of Finance and Economics

A direct as well as iterative method(called the orthogonally accumulated projection method, or the OAP for short) for solving linear system of equations with symmetric coefficient matrix is introduced in this paper. With the Lanczos process the OAP creates a sequence of mutually orthogonal vectors, on the basis of which the projections of the unknown vectors are easily obtained, and thus the approximations to the unknown vectors can be simply constructed by a combination of these projections. This method is an application of the accumulated projection technique proposed recently by the authors of this paper, and can be regarded as a match of conjugate gradient method(CG) in its nature since both the CG and the OAP can be regarded as iterative methods, too. Unlike the CG method which can be only used to solve linear systems with symmetric positive definite coefficient matrices, the OAP can be used to handle systems with indefinite symmetric matrices. Unlike classical Krylov subspace methods which usually ignore the issue of loss of orthogonality, OAP uses an effective approach to detect the loss of orthogonality and a restart strategy is used to handle the loss of *** experiments are presented to demonstrate the efficiency of the OAP.

关键词： iterative method accumulated projection conjugate gradient method Krylov subspace

Optimal Control of Nonlinear Switched Systems:Computational Methods and Applications

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Journal of the Operations Research Society of China 2013年第3期1卷 275-311页

作者： qun lin Ryan Loxton Kok Lay Teo Department of Mathematics and Statistics Curtin UniversityPerthAustralia

A switched system is a dynamic system that operates by switching between different subsystems or *** systems exhibit both continuous and discrete characteristics—a dual nature that makes designing effective control policies a challenging *** purpose of this paper is to review some of the latest computational techniques for generating optimal control laws for switched systems with nonlinear dynamics and continuous inequality *** discuss computational strategies for optimizing both the times at which a switched system switches from one mode to another(the so-called switching times)and the sequence in which a switched system operates its various possible modes(the so-called switching sequence).These strategies involve novel combinations of the control parameterization method,the timescaling transformation,and bilevel programming and binary relaxation *** conclude the paper by discussing a number of switched system optimal control models arising in practical applications.

关键词： Switched system Nonlinear system Optimal control Nonlinear optimization

Heat Treatment of Cold-Rolled Low-Carbon Si-Mn Dual Phase Steels

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Journal of Iron and Steel Research International 2010年第1期17卷 54-58页

作者： LUO Juan-juan SHI Wen HUANG qun-fei LI lin Material Science and Engineering College Shanghai University Shanghai 200072 China

The effects of overageing （OA） and vanadium addition on microstructure and properties of cold-rolled lowcarbon Si-Mn dual phase （DP） steel sheets are studied. The results show that the microstructure and mechanical properties of DP steels are greatly affected by OA temperature. When OA is done at low temperatures （473 -- 573 K）, the elongation rate increases sharply while both the yield strength and tensile strength decrease significantly, When OA is done at high temperatures （〉573 K）, the elongation does not further increase, but the yield strength increases and tensile strength decreases, which deteriorates the mechanical properties of the steel. The results also show that both the strength and the tempering stability can be significantly improved by vanadium microalloying. Finally, the optimum OA temperature for the traditional steel appears to be around 523 K, while it is around 573 K for the V-containing steel, resulting in the best overall mechanical properties.

关键词： dual phase steel overageing microstructure mechanical property vanadium

Boosting self-trapped exciton emission from Cs_(3)Cu_(2)I_(5)nanocrystals by doping-enhanced exciton-phonon coupling

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Nano Research 2023年第7期16卷 10476-10482页

作者： Xiaohan Li Aijun Liu Zhaoyu Wang Youchao Wei qun lin Yameng Chen Yongsheng Liu Maochun Hong College of Chemistry Fuzhou UniversityFuzhou 350116China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China

Self-trapped excitons(STEs)emission from halide perovskites with strong exciton-phonon coupling has attracted considerable attention due to the widespread application in optoelectronic ***,the in-depth understanding of the relationship between exciton-phonon coupling and luminescence intensity remains ***,a doping-enhanced exciton-phonon coupling effect is observed in Cs_(3)Cu_(2)I_(5)nanocrystals(NCs),which leads to a remarkable increasement of their STEs emission *** study shows that the hetero-valent substitution of Cu+with alkaline-earth metal ions(AE^(2+))causes a greater degree of Jahn-Teller distortion between the ground state and excited state structures of[Cu_(2)I_(5)]_(3)-clusters as evidenced by our spectral analysis and first-principles *** a consequence,an X-ray detector based on these Cs_(3)Cu_(2)I_(5):AE NCs delivers an X-ray imaging resolution of up to 10 lp·mm^(-1) and a low detection limit of 0.37μGyair·s^(-1),disclosing the potential of doping-enhanced exciton-phonon coupling effect in improving STEs-emission and practical application for X-ray imaging.

关键词： Cs_(3)Cu_(2)I_(5) nanocrystals self-trapped exciton exciton-phonon coupling X-ray image