A group of asymmetric difference schemes to approach the Korteweg-de Vries （KdV） equation is given here. According to such schemes, the full explicit difference scheme and the full implicit one, an alternating segme...A group of asymmetric difference schemes to approach the Korteweg-de Vries （KdV） equation is given here. According to such schemes, the full explicit difference scheme and the full implicit one, an alternating segment explicit-implicit difference scheme for solving the KdV equation is constructed. The scheme is linear unconditionally stable by the analysis of linearization procedure, and is used directly on the parallel computer. The numerical experiments show that the method has high accuracy.展开更多
The numerical solution of large scale multi-dimensional convection diffusion equations often requires efficient parallel algorithms.In this work,we consider the extension of a recently proposed non-overlapping domain ...The numerical solution of large scale multi-dimensional convection diffusion equations often requires efficient parallel algorithms.In this work,we consider the extension of a recently proposed non-overlapping domain decomposition method for two dimensional time dependent convection diffusion equations with variable coefficients. By combining predictor-corrector technique,modified upwind differences with explicitimplicit coupling,the method under consideration provides intrinsic parallelism while maintaining good stability and accuracy.Moreover,for multi-dimensional problems, the method can be readily implemented on a multi-processor system and does not have the limitation on the choice of subdomains required by some other similar predictor-corrector or stabilized schemes.These properties of the method are demonstrated in this work through both rigorous mathematical analysis and numerical experiments.展开更多
Many engineering applications need to analyse the system dynamics on the macro and micro level,which results in a larger computational effort.An explicit-implicit asynchronous step algorithm is introduced to solve the...Many engineering applications need to analyse the system dynamics on the macro and micro level,which results in a larger computational effort.An explicit-implicit asynchronous step algorithm is introduced to solve the structural dynamics in multi-scale both the space domain and time domain.The discrete FEA model is partitioned into explicit and implicit parts using the nodal partition method.Multiple boundary node method is adopted to handle the interface coupled problem.In coupled region,the implicit Newmark coupled with an explicit predictor corrector Newmark whose predictive wave propagates into the implicit mesh.During the explicit subcycling process,the variables of boundary nodes are solved directly by dynamics equilibrium equation.The dissipation energy is dynamically determined in accordance with the energy balance checking.A cantilever beam and a building two numerical examples are proposed to verify that the method can greatly reduce the computing time while maintaining a high accuracy.展开更多
The solution of time-dependent hyperbolic conservation laws on cut cell meshes causes the small cell problem:standard schemes are not stable on the arbitrarily small cut cells if an explicit time stepping scheme is us...The solution of time-dependent hyperbolic conservation laws on cut cell meshes causes the small cell problem:standard schemes are not stable on the arbitrarily small cut cells if an explicit time stepping scheme is used and the time step size is chosen based on the size of the background cells.In May and Berger(J Sci Comput 71:919–943,2017),the mixed explicit-implicit approach in general and MUSCL-Trap(monotonic upwind scheme for conservation laws and trapezoidal scheme)in particular have been introduced to solve this problem by using implicit time stepping on the cut cells.Theoretical and numerical results have indicated that this might lead to a loss in accuracy when switching between the explicit and implicit time stepping.In this contribution,we examine this in more detail and will prove in one dimension that the specific combination MUSCL-Trap of an explicit second-order and an implicit second-order scheme results in a fully second-order mixed scheme.As this result is unlikely to hold in two dimensions,we also introduce two new versions of mixed explicit-implicit schemes based on exchanging the explicit scheme.We present numerical tests in two dimensions where we compare the new versions with the original MUSCL-Trap scheme.展开更多
Corrected explicit-implicit domain decomposition(CEIDD) algorithms are studied for parallel approximation of semilinear parabolic problems on distributed memory processors. It is natural to divide the spatial domain i...Corrected explicit-implicit domain decomposition(CEIDD) algorithms are studied for parallel approximation of semilinear parabolic problems on distributed memory processors. It is natural to divide the spatial domain into some smaller parallel strips and cells using the simplest straightline interface(SI) . By using the Leray-Schauder fixed-point theorem and the discrete energy method,it is shown that the resulting CEIDD-SI algorithm is uniquely solvable,unconditionally stable and convergent. The CEIDD-SI method always suffers from the globalization of data communication when interior boundaries cross into each other inside the domain. To overcome this disadvantage,a composite interface(CI) that consists of straight segments and zigzag fractions is suggested. The corresponding CEIDD-CI algorithm is proven to be solvable,stable and convergent. Numerical experiments are presented to support the theoretical results.展开更多
In this paper,we discuss the local discontinuous Galerkin methods coupled with two specific explicitimplicit-null time discretizations for solving one-dimensional nonlinear diffusion problems Ut=(a(U)Ux)x.The basic id...In this paper,we discuss the local discontinuous Galerkin methods coupled with two specific explicitimplicit-null time discretizations for solving one-dimensional nonlinear diffusion problems Ut=(a(U)Ux)x.The basic idea is to add and subtract two equal terms a0 Uxx the right-hand side of the partial differential equation,then to treat the term a0 Uxx implicitly and the other terms(a(U)Ux)x-a0 Uxx explicitly.We give stability analysis for the method on a simplified model by the aid of energy analysis,which gives a guidance for the choice of a0,i.e.,a0≥max{a(u)}/2 to ensure the unconditional stability of the first order and second order schemes.The optimal error estimate is also derived for the simplified model,and numerical experiments are given to demonstrate the stability,accuracy and performance of the schemes for nonlinear diffusion equations.展开更多
尽管从方法运用角度对文史文本深度翻译的探讨已经相当丰富,但在实施深度翻译方法之前,确立指导原则的重要性仍然不容忽视。这些原则为文史文本深度翻译实践提供了指导和规范,确保了深度翻译的准确性和一致性,并具有更广泛的适用性。在...尽管从方法运用角度对文史文本深度翻译的探讨已经相当丰富,但在实施深度翻译方法之前,确立指导原则的重要性仍然不容忽视。这些原则为文史文本深度翻译实践提供了指导和规范,确保了深度翻译的准确性和一致性,并具有更广泛的适用性。在翻译威尔森的英国通俗史畅销书《后维多利亚时代人》(After the Victorians)中,笔者较多地运用了阿皮亚最早提出的深度翻译方法,采用的具体分类是曹明伦提出的显性深度翻译和隐性深度翻译。本文将对曹明伦重新归纳出的显性深度翻译与隐性深度翻译的方法做一简要介绍,包括隐性深度翻译的提出过程,然后重点结合笔者翻译《后维多利亚时代人》的实践,讨论一般史学著作深度翻译应遵循的原则。在讨论中,本文将涵盖上述两种深度翻译方法的操作与例析。展开更多
目的探究高特质焦虑个体认知重评和表达抑制的使用习惯及其在内隐/外显条件下使用2种情绪调节策略的特点。方法于2023年6月至2023年7月招募57名某军医大学非心理学专业本科生或研究生被试。采用特质焦虑量表(Trait form of Spielberger...目的探究高特质焦虑个体认知重评和表达抑制的使用习惯及其在内隐/外显条件下使用2种情绪调节策略的特点。方法于2023年6月至2023年7月招募57名某军医大学非心理学专业本科生或研究生被试。采用特质焦虑量表(Trait form of Spielberger’s State-Trait Anxiety Inventory,STAI-T)和情绪调节问卷(Emotion Regulation Questionnaire,ERQ)对其焦虑水平以及认知重评和表达抑制2种策略的使用习惯进行调查。按照STAI-T得分将其分为高特质焦虑(high trait anxiety,HTA)和低特质焦虑(low trait anxiety,LTA)2组,其中HTA组28例,LTA组29例,并采用内隐和外显情绪调节任务分析比较2种策略对负性情绪愉悦度和唤醒度的改善效果,以及外显条件下2种策略的难度和成功度差异。结果①2组均习惯于使用认知重评,而较少使用表达抑制[t(27)=3.94,P<0.001;t(28)=11.33,P<0.001];相较于LTA个体,HTA个体表达抑制的使用频率更高[t(55)=3.02,P<0.01],而认知重评的使用频率较低[t(55)=-2.20,P=0.02];②内隐条件下,相对于中性启动,认知重评(愉悦度:2.56±0.11 vs 2.73±0.12,P<0.01;唤醒度:6.68±0.18 vs 6.51±0.20,P<0.05)和表达抑制启动(愉悦度:2.56±0.11 vs 2.86±0.11,P<0.001;唤醒度:6.68±0.18 vs 6.30±0.20,P<0.001)都可改善2组被试的负性情绪体验,且表达抑制的效果更好(愉悦度:P<0.001,唤醒度:P<0.001)。③外显条件下,认知重评(愉悦度:2.92±0.12 vs 5.09±0.09,P<0.001;唤醒度:6.43±0.20 vs 4.33±0.21,P<0.001)和表达抑制(愉悦度:2.92±0.12 vs 4.34±0.09,P<0.001;唤醒度:6.43±0.20 vs 4.22±0.22,P<0.001)均可显著改善HTA和LTA个体的负性情绪体验,且认知重评对愉悦度的提升优于表达抑制(P<0.001);不同特质焦虑水平间比较显示HTA个体对两种情绪调节策略的使用均显得更为困难[认知重评:t(55)=2.16,P=0.02;表达抑制:t(55)=2.92,P<0.01],且表达抑制的情绪调节成功度更低[t(55)=-1.88,P=0.03];对HTA个体自身而言,使用表达抑制的难度要大于认知重评[4.00±1.81 vs 5.00±1.80,t(27)=-2.78,P<0.01],且成功度更低[7.04±1.00 vs 6.64±1.13,t(27)=2.09,P=0.02]。④比较内隐和外显条件下的情绪调节效应,发现高、低特质焦虑个体外显情绪调节对愉悦度(外显重评vs内隐重评:5.09±0.09 vs 2.73±0.12,P<0.001;外显抑制vs内隐抑制:4.34±0.09 vs 2.86±0.11,P<0.001)和唤醒度(外显重评vs内隐重评:4.33±0.21 vs 6.51±0.20,P<0.001;外显抑制vs内隐抑制:4.22±0.22 vs 6.30±0.20,P<0.001)的改善效果均优于内隐条件。结论高特质焦虑个体存在认知重评使用相对不足、表达抑制使用偏多的特点;在内隐和外显条件下,认知重评和表达抑制均能有效改善高特质焦虑个体的负性情绪体验,且外显情绪调节的效果均优于内隐。展开更多
基金Project supported by the National Natural Science Foundation of China(No.10671113)the Natural Science Foundation of Shandong Province of China(No.Y2003A04)
文摘A group of asymmetric difference schemes to approach the Korteweg-de Vries （KdV） equation is given here. According to such schemes, the full explicit difference scheme and the full implicit one, an alternating segment explicit-implicit difference scheme for solving the KdV equation is constructed. The scheme is linear unconditionally stable by the analysis of linearization procedure, and is used directly on the parallel computer. The numerical experiments show that the method has high accuracy.
基金the National Natural Science Foundation of China(No.10571017)supported in part by the National Natural Science Foundation of China(No.60533020)supported in part by NSF DMS 0712744
文摘The numerical solution of large scale multi-dimensional convection diffusion equations often requires efficient parallel algorithms.In this work,we consider the extension of a recently proposed non-overlapping domain decomposition method for two dimensional time dependent convection diffusion equations with variable coefficients. By combining predictor-corrector technique,modified upwind differences with explicitimplicit coupling,the method under consideration provides intrinsic parallelism while maintaining good stability and accuracy.Moreover,for multi-dimensional problems, the method can be readily implemented on a multi-processor system and does not have the limitation on the choice of subdomains required by some other similar predictor-corrector or stabilized schemes.These properties of the method are demonstrated in this work through both rigorous mathematical analysis and numerical experiments.
基金supported by the National Key Research and Development Program of China(2016YFB0201800)the National Natural Science Foundation of China(No.51475287 and No.11772192).
文摘Many engineering applications need to analyse the system dynamics on the macro and micro level,which results in a larger computational effort.An explicit-implicit asynchronous step algorithm is introduced to solve the structural dynamics in multi-scale both the space domain and time domain.The discrete FEA model is partitioned into explicit and implicit parts using the nodal partition method.Multiple boundary node method is adopted to handle the interface coupled problem.In coupled region,the implicit Newmark coupled with an explicit predictor corrector Newmark whose predictive wave propagates into the implicit mesh.During the explicit subcycling process,the variables of boundary nodes are solved directly by dynamics equilibrium equation.The dissipation energy is dynamically determined in accordance with the energy balance checking.A cantilever beam and a building two numerical examples are proposed to verify that the method can greatly reduce the computing time while maintaining a high accuracy.
文摘The solution of time-dependent hyperbolic conservation laws on cut cell meshes causes the small cell problem:standard schemes are not stable on the arbitrarily small cut cells if an explicit time stepping scheme is used and the time step size is chosen based on the size of the background cells.In May and Berger(J Sci Comput 71:919–943,2017),the mixed explicit-implicit approach in general and MUSCL-Trap(monotonic upwind scheme for conservation laws and trapezoidal scheme)in particular have been introduced to solve this problem by using implicit time stepping on the cut cells.Theoretical and numerical results have indicated that this might lead to a loss in accuracy when switching between the explicit and implicit time stepping.In this contribution,we examine this in more detail and will prove in one dimension that the specific combination MUSCL-Trap of an explicit second-order and an implicit second-order scheme results in a fully second-order mixed scheme.As this result is unlikely to hold in two dimensions,we also introduce two new versions of mixed explicit-implicit schemes based on exchanging the explicit scheme.We present numerical tests in two dimensions where we compare the new versions with the original MUSCL-Trap scheme.
基金supported by National Natural Science Foundation of China (Grant No. 10871044)
文摘Corrected explicit-implicit domain decomposition(CEIDD) algorithms are studied for parallel approximation of semilinear parabolic problems on distributed memory processors. It is natural to divide the spatial domain into some smaller parallel strips and cells using the simplest straightline interface(SI) . By using the Leray-Schauder fixed-point theorem and the discrete energy method,it is shown that the resulting CEIDD-SI algorithm is uniquely solvable,unconditionally stable and convergent. The CEIDD-SI method always suffers from the globalization of data communication when interior boundaries cross into each other inside the domain. To overcome this disadvantage,a composite interface(CI) that consists of straight segments and zigzag fractions is suggested. The corresponding CEIDD-CI algorithm is proven to be solvable,stable and convergent. Numerical experiments are presented to support the theoretical results.
基金supported by National Natural Science Foundation of China(Grant Nos.11601241,11671199,11571290 and 11672082)Natural Science Foundation of Jiangsu Province(Grant No.BK20160877)+1 种基金ARO(Grant No.W911NF-15-1-0226)National Science Foundation of USA(Grant No.DMS-1719410)
文摘In this paper,we discuss the local discontinuous Galerkin methods coupled with two specific explicitimplicit-null time discretizations for solving one-dimensional nonlinear diffusion problems Ut=(a(U)Ux)x.The basic idea is to add and subtract two equal terms a0 Uxx the right-hand side of the partial differential equation,then to treat the term a0 Uxx implicitly and the other terms(a(U)Ux)x-a0 Uxx explicitly.We give stability analysis for the method on a simplified model by the aid of energy analysis,which gives a guidance for the choice of a0,i.e.,a0≥max{a(u)}/2 to ensure the unconditional stability of the first order and second order schemes.The optimal error estimate is also derived for the simplified model,and numerical experiments are given to demonstrate the stability,accuracy and performance of the schemes for nonlinear diffusion equations.
文摘尽管从方法运用角度对文史文本深度翻译的探讨已经相当丰富,但在实施深度翻译方法之前,确立指导原则的重要性仍然不容忽视。这些原则为文史文本深度翻译实践提供了指导和规范,确保了深度翻译的准确性和一致性,并具有更广泛的适用性。在翻译威尔森的英国通俗史畅销书《后维多利亚时代人》(After the Victorians)中,笔者较多地运用了阿皮亚最早提出的深度翻译方法,采用的具体分类是曹明伦提出的显性深度翻译和隐性深度翻译。本文将对曹明伦重新归纳出的显性深度翻译与隐性深度翻译的方法做一简要介绍,包括隐性深度翻译的提出过程,然后重点结合笔者翻译《后维多利亚时代人》的实践,讨论一般史学著作深度翻译应遵循的原则。在讨论中,本文将涵盖上述两种深度翻译方法的操作与例析。
文摘目的探究高特质焦虑个体认知重评和表达抑制的使用习惯及其在内隐/外显条件下使用2种情绪调节策略的特点。方法于2023年6月至2023年7月招募57名某军医大学非心理学专业本科生或研究生被试。采用特质焦虑量表(Trait form of Spielberger’s State-Trait Anxiety Inventory,STAI-T)和情绪调节问卷(Emotion Regulation Questionnaire,ERQ)对其焦虑水平以及认知重评和表达抑制2种策略的使用习惯进行调查。按照STAI-T得分将其分为高特质焦虑(high trait anxiety,HTA)和低特质焦虑(low trait anxiety,LTA)2组,其中HTA组28例,LTA组29例,并采用内隐和外显情绪调节任务分析比较2种策略对负性情绪愉悦度和唤醒度的改善效果,以及外显条件下2种策略的难度和成功度差异。结果①2组均习惯于使用认知重评,而较少使用表达抑制[t(27)=3.94,P<0.001;t(28)=11.33,P<0.001];相较于LTA个体,HTA个体表达抑制的使用频率更高[t(55)=3.02,P<0.01],而认知重评的使用频率较低[t(55)=-2.20,P=0.02];②内隐条件下,相对于中性启动,认知重评(愉悦度:2.56±0.11 vs 2.73±0.12,P<0.01;唤醒度:6.68±0.18 vs 6.51±0.20,P<0.05)和表达抑制启动(愉悦度:2.56±0.11 vs 2.86±0.11,P<0.001;唤醒度:6.68±0.18 vs 6.30±0.20,P<0.001)都可改善2组被试的负性情绪体验,且表达抑制的效果更好(愉悦度:P<0.001,唤醒度:P<0.001)。③外显条件下,认知重评(愉悦度:2.92±0.12 vs 5.09±0.09,P<0.001;唤醒度:6.43±0.20 vs 4.33±0.21,P<0.001)和表达抑制(愉悦度:2.92±0.12 vs 4.34±0.09,P<0.001;唤醒度:6.43±0.20 vs 4.22±0.22,P<0.001)均可显著改善HTA和LTA个体的负性情绪体验,且认知重评对愉悦度的提升优于表达抑制(P<0.001);不同特质焦虑水平间比较显示HTA个体对两种情绪调节策略的使用均显得更为困难[认知重评:t(55)=2.16,P=0.02;表达抑制:t(55)=2.92,P<0.01],且表达抑制的情绪调节成功度更低[t(55)=-1.88,P=0.03];对HTA个体自身而言,使用表达抑制的难度要大于认知重评[4.00±1.81 vs 5.00±1.80,t(27)=-2.78,P<0.01],且成功度更低[7.04±1.00 vs 6.64±1.13,t(27)=2.09,P=0.02]。④比较内隐和外显条件下的情绪调节效应,发现高、低特质焦虑个体外显情绪调节对愉悦度(外显重评vs内隐重评:5.09±0.09 vs 2.73±0.12,P<0.001;外显抑制vs内隐抑制:4.34±0.09 vs 2.86±0.11,P<0.001)和唤醒度(外显重评vs内隐重评:4.33±0.21 vs 6.51±0.20,P<0.001;外显抑制vs内隐抑制:4.22±0.22 vs 6.30±0.20,P<0.001)的改善效果均优于内隐条件。结论高特质焦虑个体存在认知重评使用相对不足、表达抑制使用偏多的特点;在内隐和外显条件下,认知重评和表达抑制均能有效改善高特质焦虑个体的负性情绪体验,且外显情绪调节的效果均优于内隐。
