检索结果-南通市图书馆

Science China Mathematics 2017年第7期60卷 1341-1352页

作者： CHEN ChuanMiao hu hongling Key Laboratory of HPCSIP(Ministry of Education of China) College of Mathematics and Computer ScienceHunan Normal University

To solve nonlinear system of equation,F(x) = 0,a continuous Newton flow x_t(t) = V(x) =-(DF(x))^(-1)F(x),x(0) =x^0 and its mathematical properties,such as the central field,global existence and uniqueness of real roots and the structure of the singular surface,are *** concisely introduce random Newton flow algorithm(NFA) for finding all roots,based on discrete Newton flow x^(j+1)=x^j+hV{x^j) with random initial value x^0 and h∈(0,1],and three computable quantities,g_j,d_j and K_*** numerical experiments with dimension n=300 are provided.

关键词： nonlinear system of equation continuous Newton flow real roots global existence and uniqueness random Newton flow algorithm

Extrapolation cascadic multigrid method on piecewise uniform grid

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2013年第12期56卷 2711-2722页

作者： CHEN ChuanMiao hu hongling College of Mathematics and Computer Science Key Laboratory of High Performance Computing and Stochastic Information Processing (Ministry of Education of China)Hunan Normal University

The triangular linear finite elements on piecewise uniform grid for an elliptic problem in convex polygonal domain are discussed. Global superconvergence in discrete Hi-norm and global extrapolation in discrete L2-norm are proved. Based on these global estimates the conjugate gradient method （CG） is effective, which is applied to extrapolation cascadic multigrid method （EXCMG）. The numerical experiments show that EXCMG is of the global higher accuracy for both function and gradient.

关键词： linear finite element piecewise uniform grid superconvergence extrapolation extrapolation cas-cadic multigrid method

TIME-EXTRAPOLATION ALGORITHM （TEA） FOR LINEAR PARABOLIC PROBLEMS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2014年第2期32卷 183-194页

作者： hongling hu Chuanmiao Chen Kejia Pan College of Mathematics and Computer Science Key Laboratory of High Performance Computing and Stochastic Information Processing (HPCSIP) (Ministry of Education of China) Hunan Normal University Changsha 410081 China School of Mathematics and Statistics Central South University Changsha 410083 China

The fast solutions of Crank-Nicolson scheme on quasi-uniform mesh for parabolic prob- lems are discussed. First, to decrease regularity requirements of solutions, some new error estimates are proved. Second, we analyze the two characteristics of parabolic discrete scheme, and find that the efficiency of Multigrid Method （MG） is greatly reduced. Nu- merical experiments compare the efficiency of Direct Conjugate Gradient Method （DCG） and Extrapolation Cascadic Multigrid Method （EXCMG）. Last, we propose a Time- Extrapolation Algorithm （TEA）, which takes a linear combination of previous several level solutions as good initial values to accelerate the rate of convergence. Some typical extrapolation formulas are compared numerically. And we find that under certain accuracy requirement, the CG iteration count for the 3-order and 7-level extrapolation formula is about 1/3 of that of DCG＇s. Since the TEA algorithm is independent of the space dimension, it is still valid for quasi-uniform meshes. As only the finest grid is needed, the proposed method is regarded very effective for nonlinear parabolic problems.

关键词： Parabolic problem Crank-Nicolson scheme Error estimates Time-extrapolationalgorithm CG-iteration.

ON EXTRAPOLATION CASCADIC MULTIGRID METHOD

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2011年第6期29卷 684-697页

作者： Chuanmiao Chen Zhong-Ci Shi hongling hu Institute of Computation Hunan Normal University Changsha 410081 China LSEC ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

Based on an asymptotic expansion of （bi）linear finite elements, a new extrapolation formula and extrapolation cascadic multigrid method （EXCMG） are proposed. The key ingredients of the proposed methods are some new extrapolations and quadratic interpolations, which are used to provide better initial values on the refined grid. In the case of triple grids, the errors of the new initial values are analyzed in detail. The numerical experiments show that EXCMG has higher accuracy and efficiency.

关键词： Cascadic multigrid Finite element New extrapolation Error analysis.

Asymptotic expansions of finite element solutions to Robin problems in H^3 and their application in extrapolation cascadic multigrid method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2014年第4期57卷 687-698页

作者： hu hongling CHEN ChuanMiao PAN KeJia College of Mathematics and Computer Science Key Laboratory of High Performance Computing and Stochastic Information Processing (Ministry of Education of China)Hunan Normal University School of Mathematics and Statistics Central South University Key Laboratory of Metallogenic Prediction of Nonferrous Metals Ministry of EducationSchool of Geosciences and Info-PhysicsCentral South University

For the Poisson equation with Robin boundary conditions,by using a few techniques such as orthogonal expansion(M-type),separation of the main part and the finite element projection,we prove for the first time that the asymptotic error expansions of bilinear finite element have the accuracy of O(h3)for u∈*** on the obtained asymptotic error expansions for linear finite elements,extrapolation cascadic multigrid method(EXCMG)can be used to solve Robin problems ***,by virtue of Richardson not only the accuracy of the approximation is improved,but also a posteriori error estimation is ***,some numerical experiments that confirm the theoretical analysis are presented.

关键词： finite element Richardson extrapolation Robin problem asymptotic expansion cascadic multi-grid method

Analysis of extrapolation cascadic multigrid method(EXCMG)

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2008年第8期51卷 1349-1360页

作者： CHEN ChuanMiao hu hongling XIE ZiQing LI ChenLiang College of Mathematics and Computer Science Hunan Normal UniversityChangsha 410081China

Based on an asymptotic expansion of finite element,a new extrapolation formula and extrapolation cascadic multigrid method(EXCMG)are proposed,in which the new extrapolation and quadratic interpolation are used to provide a better initial value on refined *** the case of triple grids,the error of the new initial value is analyzed in detail.A larger scale computation is completed in PC.

关键词： cascadic multigrid finite element new extrapolation error analysis 65N30

New Sixth-Order Compact Schemes for Poisson/Helmholtz Equations

在线全文

学校读者我要写书评

暂无评论

Numerical Mathematics(Theory,Methods and Applications) 2023年第2期16卷 393-409页

作者： Kejia Pan Kang Fu Jin Li hongling hu Zhilin Li School of Mathematics and Statistics HNP-LAMACentral South UniversityChangsha 410083China MOE-LCSM School of Mathematics and StatisticsHunan Normal UniversityChangsha 410081China CRSC&Department of Mathematics North Carolina State UniversityRaleighNC 27695-8205USA

Some new sixth-order compact finite difference schemes for Poisson/Helmholtz equations on rectangular domains in both two-and three-dimensions are developed and *** from a few sixth-order compact finite difference schemes in the literature,the finite difference and weight coefficients of the new methods have analytic simple *** of the new ideas is to use a weighted combination of the source term at staggered grid points which is important for grid points near the boundary and avoids partial derivatives of the source ***,the new compact schemes are exact for 2D and 3D Poisson equations if the solution is a polynomial less than or equal to *** coefficient matrices of the new schemes are M-matrices for Helmholtz equations with wave number K≤0,which guarantee the discrete maximum principle and lead to the convergence of the new sixth-order compact *** examples in both 2D and 3D are presented to verify the effectiveness of the proposed schemes.

关键词： Poisson equation Helmholtz equation sixth-order compact scheme maximum principle staggered grid.

Secretogranln-II plays a critical role in zebrafis neurovascular modeling

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Molecular Cell Biology 2018年第5期10卷 388-401页

作者： Binbin Tao hongling hu Kimberly Mitchell Ji Chen Haibo Jia Zuoyan Zhu Vance L. Trudeau Wei hu State Key Laboratory of Freshwater Ecology and Biotechnology Institute of Hydrobiology Chinese Academy of Sciences Wuhan 430072 China University of the Chinese Academy of Sciences Beijing 10049 China Department of Biology University of Ottawa Ottawa Ontario K1N 6N5 Canada Key Laboratory of Molecular Biophysics of Ministry of Education College of Life Science and Technology HuaZhong University of Science and Technology Wuhan 430074 China

Secretoneurin （SN） is a neuropeptide derived from specific proteolytic processing of the precursor secretogranin II （Sgll）. In zebrafish and other teleosts, there are two paralogs named sglla and sgllb. Our results showed that neurons expressing sgllb were aligned with central arteries in the hindbrain, demonstrating a close neurovascular association. Both sgllb-/- and sgllo-/-/sgllb-/- mutant embryos were defective in hindbrain central artery development due to impairment of migration and proliferation of central artery cells. Further study revealed that sgllb is non-ceU autonomous and required for central artery development. Hindbrain arterial and venous network identities were not affected in sgllb-/- mutant embryos, and the mRNA levels of Notch and VEGF pathway-related genes were not altered. However, the activation of MAPK and PI3K/AKT pathways was inhibited in sgllb-/- mutant embryos. Reactivation of MAPK or PI3K/AKT in endothelial cells could partially rescue the central artery developmental defects in the sgllb mutants. This studV provides the first in vivo evidence that sgllb ptavs a critical rote in neurovascutar modeling of the hindbrain. Targeting the Sgll system may, therefore, represent a new avenue for the treatment of vascular defects in the central nervous system.

关键词： Secretogranin-II secretoneurin TALENs neurovascular zebrafish

Effect of Fertilization on Anatomical and Physical-mechanical Properties of Neosinocalamus Affinis Bamboo

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Bioresources and Bioproducts 2019年第1期4卷 67-72页

作者： Jiulong XIE Jinqiu QI hongling hu Cornelis F DE HOOP hui XIAO Yuzhu CHEN Chungyun HSE College of Forestry Sichuan Agricultural UniversityChengdu 611130China School of Renewable Natural Resource Louisiana State University Agricultural CenterBaton RougeLA70803USA Southern Research Station USDA Forest ServicePinevilleLA71360USA

In order to maintain soil fertility of Neosinocalamus affinis plantations,fertilizers of N,P,and K were *** anatomical and physical-mechanical properties of *** bamboo wood from different fertilization treatments were *** aim of this study was to elucidate the effect of fertilization practice on the properties of *** bamboo *** results revealed that the fertilization of P and K resulted in a slight reduction in fiber *** application of P,K,and low level(0.3 kg/clump)of N fertilizers had no significant effect on the fiber morphology,while high level(0.9 kg/clump)of N fertilizer contributed to short *** specific gravity was significantly decreased by fertilization,while the volume shrinkage was *** the effect of various fertilization treatments had different influence patterns on the properties of ***,specific evaluations on the quality of the fertilized bamboo wood should be performed prior to its utilization.

关键词： fertilization anatomy physical-mechanical properties Neosinocalamus affinis

环境保护按日计罚制度适用反思与完善——以美国环境保护按日连续处罚制度为借鉴

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

政治与法律 2018年第8期 150-160页

作者：胡红玲中南大学法学院湖南长沙410000

我国《环境保护法》规定的按日连续处罚制度设计尚不够完善,除了法律性质界定不明外,还存在可适用的违法行为类别较少,计罚考量因素不多等问题,其导致的结果是该处罚制度的可操作性不强,执法实践中适用率很低。作为按日连续处罚制度发... 详细信息

我国《环境保护法》规定的按日连续处罚制度设计尚不够完善,除了法律性质界定不明外,还存在可适用的违法行为类别较少,计罚考量因素不多等问题,其导致的结果是该处罚制度的可操作性不强,执法实践中适用率很低。作为按日连续处罚制度发源地的美国,其对按日连续处罚的法律性质定位清晰,将其适用于各种违法行为,并从多方面设置计罚标准,执法机关还通过发布民事罚款政策保证处罚评定过程的一致性,使其具有很强的可操作性。我国《环境保护法》第59条有关按日计罚的规定及该制度的实施办法均需进一步完善,要明确其行政罚性质和地方法规对其设置的权限,扩大其适用范围并增加计罚考量因素,以实现各方利益衡平,并将执法人员的自由裁量权控制在一定的范围之内。

关键词：环境保护法按日计罚利益衡平地方法规设定权自由裁量权