检索结果-南通市图书馆

Journal of Computational Mathematics 2024年第1期42卷 111-133页

作者： ruihan guo Yan Xu School of Mathematics and Statistics Zhengzhou UniversityZhengzhou 450001China School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026China

In[20],a semi-implicit spectral deferred correction(SDC)method was proposed,which is efficient for highly nonlinear partial differential equations(PDEs).The semi-implicit SDC method in[20]is based on first-order time integration methods,which are corrected iteratively,with the order of accuracy increased by one for each additional iteration.In this paper,we will develop a class of semi-implicit SDC methods,which are based on second-order time integration methods and the order of accuracy are increased by two for each additional iteration.For spatial discretization,we employ the local discontinuous Galerkin(LDG)method to arrive at fully-discrete schemes,which are high-order accurate in both space and time.Numerical experiments are presented to demonstrate the accuracy,efficiency and robustness of the proposed semi-implicit SDC methods for solving complex nonlinear PDEs.

关键词： Spectral deferred correction method Nonlinear PDEs Local discontinuous Galerkin method Second-order scheme

Arbitrary High-Order Fully-Decoupled Numerical Schemes for Phase-Field Models of Two-Phase Incompressible Flows

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications on Applied Mathematics and Computation 2024年第1期6卷 625-657页

作者： ruihan guo Yinhua Xia School of Mathematics and Statistics Zhengzhou UniversityZhengzhou450001HenanChina School of Mathematical Sciences University of Science and Technology of ChinaHefei230026AnhuiChina

Due to the coupling between the hydrodynamic equation and the phase-field equation in two-phase incompressible flows,it is desirable to develop efficient and high-order accurate numerical schemes that can decouple these two equations.One popular and efficient strategy is to add an explicit stabilizing term to the convective velocity in the phase-field equation to decouple them.The resulting schemes are only first-order accurate in time,and it seems extremely difficult to generalize the idea of stabilization to the second-order or higher version.In this paper,we employ the spectral deferred correction method to improve the temporal accuracy,based on the first-order decoupled and energy-stable scheme constructed by the stabilization idea.The novelty lies in how the decoupling and linear implicit properties are maintained to improve the efficiency.Within the framework of the spatially discretized local discontinuous Galerkin method,the resulting numerical schemes are fully decoupled,efficient,and high-order accurate in both time and space.Numerical experiments are performed to validate the high-order accuracy and efficiency of the methods for solving phase-field models of two-phase incompressible flows.

关键词： Two-phase incompressible flows Fully-decoupled High-order accurate Linear implicit Spectral deferred correction method Local discontinuous Galerkin method

Optimal Error Estimates of the Semi-Discrete Local Discontinuous Galerkin Method and Exponential Time Differencing Schemes for the Thin Film Epitaxy Problem without Slope Selection

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Applied Mathematics and Mechanics 2023年第3期15卷 545-567页

作者： Danni Zhang ruihan guo School of Mathematics and Statistics Zhengzhou UniversityZhengzhouHenan 450001China

In this paper,we prove the optimal error estimates in L2 norm of the semidiscrete local discontinuous Galerkin(LDG)method for the thin film epitaxy problem without slope selection.To relax the severe time step restriction of explicit time marching methods,we employ a class of exponential time differencing(ETD)schemes for time integration,which is based on a linear convex splitting principle.Numerical experiments of the accuracy and long time simulations are given to show the efficiency and capability of the proposed numerical schemes.

关键词： Local discontinuous Galerkin method thin film epitaxy problem error estimates exponential time differencing long time simulation

A High Order Adaptive Time-Stepping Strategy and Local Discontinuous Galerkin Method for the Modified Phase Field Crystal Equation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2018年第6期24卷 123-151页

作者： ruihan guo Yan Xu School of Mathematics and Statistics Zhengzhou UniversityZhengzhouHenan 450001P.R.China School of Mathematical Sciences University of Science and Technology of ChinaHefeiAnhui 230026P.R.China

In this paper,we will develop a first order and a second order convex splitting,and a first order linear energy stable fully discrete local discontinuous Galerkin(LDG)methods for the modified phase field crystal(MPFC)equation.In which,the first order linear scheme is based on the invariant energy quadratization approach.The MPFC equation is a damped wave equation,and to preserve an energy stability,it is necessary to introduce a pseudo energy,which all increase the difficulty of constructing numerical methods comparing with the phase field crystal(PFC)equation.Due to the severe time step restriction of explicit timemarchingmethods,we introduce the first order and second order semi-implicit schemes,which are proved to be unconditionally energy stable.In order to improve the temporal accuracy,the semi-implicit spectral deferred correction(SDC)method combining with the first order convex splitting scheme is employed.Numerical simulations of the MPFC equation always need long time to reach steady state,and then adaptive time-stepping method is necessary and of paramount importance.The schemes at the implicit time level are linear or nonlinear and we solve them by multigrid solver.Numerical experiments of the accuracy and long time simulations are presented demonstrating the capability and efficiency of the proposed methods,and the effectiveness of the adaptive time-stepping strategy.

关键词： Adaptive time-stepping local discontinuous Galerkin method modified phase field crystal equation convex splitting pseudo energy unconditionally energy stable spectral deferred correction

Semi-Implicit Spectral Deferred Correction Method Based on the Invariant Energy Quadratization Approach for Phase Field Problems

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2019年第6期26卷 87-113页

This paper presents a high order time discretization method by combining the semi-implicit spectral deferred correction method with energy stable linear schemes to simulate a series of phase field problems.We start with the linear scheme,which is based on the invariant energy quadratization approach and is proved to be linear unconditionally energy stable.The scheme also takes advantage of avoiding nonlinear iteration and the restriction of time step to guarantee the nonlinear system uniquely solvable.Moreover,the scheme leads to linear algebraic system to solve at each iteration,and we employ the multigrid solver to solve it efficiently.Numerical re-sults are given to illustrate that the combination of local discontinuous Galerkin(LDG)spatial discretization and the high order temporal scheme is a practical,accurate and efficient simulation tool when solving phase field problems.Namely,we can obtain high order accuracy in both time and space by solving some simple linear algebraic equations.

关键词： Phase field problems local discontinuous Galerkin method linear scheme invariant energy quadratization approach semi-implicit spectral deferred correction method

HIGH ORDER LOCAL DISCONTINUOUS GALERKIN METHODS FOR THE ALLEN-CAHN EQUATION： ANALYSIS AND SIMULATION

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 2016年第2期34卷 135-158页

作者： ruihan guo Liangyue Ji Yan Xu School of Mathematical Sciences University of Science and Technology of China Hefei Anhui 230026 P.R. China Department of Mathematics University of Minnesota-twin cities Minneapolis MN 55455 USA

In this paper, we present a local discontinuous Galerkin （LDG） method for the AllenCahn equation. We prove the energy stability, analyze the optimal convergence rate of k ＋ 1 in L2 norm and present the （2k＋1）-th order negative-norm estimate of the semi- discrete LDG method for the Allen-Cahn equation with smooth solution. To relax the severe time step restriction of explicit time marching methods, we construct a first order semi-implicit scheme based on the convex splitting principle of the discrete Allen-Cahn energy and prove the corresponding unconditional energy stability. To achieve high order temporal accuracy, we employ the semi-implicit spectral deferred correction （SDC） method. Combining with the unconditionally stable convex splitting scheme, the SDC method can be high order accurate and stable in our numerical tests. To enhance the efficiency of the proposed methods, the multigrid solver is adapted to solve the resulting nonlinear algebraic systems. Numerical studies are presented to confirm that we can achieve optimal accuracy of （O（hk＋1） in L2 norm and improve the LDG solution from （O（hk＋1） to （O（h2k＋1） with the accuracy enhancement post-processing technique.

关键词： Local discontinuous Galerkin method Allen-Cahn equation Energy stability,Convex splitting Spectral deferred correction A priori error estimate Negative norm errorestimate.

铁路线下式站房候车空间光环境品质提升研究与实践——以福厦铁路福州南站为例

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

城市建筑 2024年第4期21卷 174-178页

作者：王凯夫周超姜睿涵袁果同济大学建筑设计研究院(集团)有限公司

线下式站房是将候车空间置于铁路轨道线的下方,受到上部轨道线路遮挡,下方候车空间难以有充足的自然采光。文章以福州南站作为特定研究对象,抓住光环境设计如何影响人的感受和行为这条主线,探讨如何利用光环境设计方法和技术提升线下式... 详细信息

线下式站房是将候车空间置于铁路轨道线的下方,受到上部轨道线路遮挡,下方候车空间难以有充足的自然采光。文章以福州南站作为特定研究对象,抓住光环境设计如何影响人的感受和行为这条主线,探讨如何利用光环境设计方法和技术提升线下式候车大厅的空间品质和旅客体验。

关键词：线下式站房光环境主观评价实验

维普期刊数据库

在线全文

学校读者我要写书评

暂无评论

我国新型研究型大学校园空间初探

城市建筑 2024年第8期21卷 5-9,18页

作者：杨华高露露郭睿涵肖家豪深圳大学建筑与城市规划学院

知识生产模式转型推动了新型研究型大学的发展,近三十年来,世界各地涌现了一批颇具实力的新型研究型大学,我国也出现了以南方科技大学和上海科技大学两所“双一流”大学为代表的多所新型研究型大学。我国的新型研究型大学在校园规划建... 详细信息

知识生产模式转型推动了新型研究型大学的发展,近三十年来,世界各地涌现了一批颇具实力的新型研究型大学,我国也出现了以南方科技大学和上海科技大学两所“双一流”大学为代表的多所新型研究型大学。我国的新型研究型大学在校园规划建设上因地制宜、因校而异、各具特色,在校园空间上又体现出相当的共性:在空间建构上体现了集约化的校园格局特征和复合化的校园功能特征;在空间情境上致力于建构高效的科研—教学—学习连结体与宜人的生活—交往—学习共同体。

关键词：新型研究型大学知识生产模式校园空间空间建构特征空间情境特征

维普期刊数据库博看期刊

臧福科教授皮部推拿治疗脑卒中急性期肌张力低下的机制、经验

在线全文

学校读者我要写书评

暂无评论

实用心脑肺血管病杂志 2024年第4期32卷 76-79页

作者：郭芮含李侠李多多杨晓明北京中医药大学第三附属医院脑病科北京市100029 北京中医药大学东直门医院推拿疼痛科北京市100700

肌张力低下是脑卒中软瘫期患者的主要临床表现之一,常在脑卒中急性期出现,且软瘫期过长、肌张力长期未提高是脑卒中患者常见且棘手的问题。有循证证据表明,康复治疗是降低脑卒中患者致残率最有效的方法,但软瘫状态下可选择的简便、经济... 详细信息

肌张力低下是脑卒中软瘫期患者的主要临床表现之一,常在脑卒中急性期出现,且软瘫期过长、肌张力长期未提高是脑卒中患者常见且棘手的问题。有循证证据表明,康复治疗是降低脑卒中患者致残率最有效的方法,但软瘫状态下可选择的简便、经济又有效的康复治疗手段较少。臧福科教授参考小儿推拿手法,将皮部推拿用于脑卒中急性期肌张力低下患者,并发现其能有效提高患者肌张力,诱发肢体快速产生自主运动,进而缩短软瘫期。本文主要综述了臧福科教授皮部推拿治疗脑卒中急性期肌张力低下的机制、经验,以期降低脑卒中致残率。

关键词：卒中肌张力低下软瘫皮部推拿综述

维普期刊数据库

一种基于QFD/TRIZ的高压铁塔微桩成型装备设计

在线全文

学校读者我要写书评

暂无评论

四川电力技术 2024年第1期47卷 72-77,110页

作者：谢伟范荣全周睿晗郑晓波郭鑫国网四川省电力公司四川成都610041 国网四川省电力公司经济技术研究院四川成都610041 四川大学机械工程学院四川成都610065 国网四川省电力公司天府新区供电公司四川成都610218

高压输电线路铁塔常位于地形条件苛刻、地质条件复杂、气象状况多变的地区,这使得大型钻孔设备难以到达施工现场,基坑开挖大多只能采用人工挖掘,但人工挖掘难以挖出变直径桩孔。为了减轻人工强度和施工风险并提高施工效率,提出了一种成... 详细信息

高压输电线路铁塔常位于地形条件苛刻、地质条件复杂、气象状况多变的地区,这使得大型钻孔设备难以到达施工现场,基坑开挖大多只能采用人工挖掘,但人工挖掘难以挖出变直径桩孔。为了减轻人工强度和施工风险并提高施工效率,提出了一种成孔设备设计方案。首先,分析了对当前桩孔钻进施工的现状以及其中存在的问题与用户需求;然后,通过质量功能展开方法从得到的用户需求中发掘出产品设计要求;最后利用发明问题解决理论求解设计要求的冲突,得到组合式变径成孔设备方案。该方案将实现成孔设备的可便捷拆卸装配以及连续变径成孔等功能,可有效地提高变径桩成孔施工的效率和安全性,相对于人工桩孔挖掘具有明显优势。

关键词：高压输电微型桩创新设计装备设计

维普期刊数据库