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A truncated implicit high-order finite-difference scheme combined with boundary conditions 被引量:2
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作者 常锁亮 刘洋 《Applied Geophysics》 SCIE CSCD 2013年第1期53-62,118,共11页
In this paper, first we calculate finite-difference coefficients of implicit finite- difference methods (IFDM) for the first and second-order derivatives on normal grids and first- order derivatives on staggered gri... In this paper, first we calculate finite-difference coefficients of implicit finite- difference methods (IFDM) for the first and second-order derivatives on normal grids and first- order derivatives on staggered grids and find that small coefficients of high-order IFDMs exist. Dispersion analysis demonstrates that omitting these small coefficients can retain approximately the same order accuracy but greatly reduce computational costs. Then, we introduce a mirrorimage symmetric boundary condition to improve IFDMs accuracy and stability and adopt the hybrid absorbing boundary condition (ABC) to reduce unwanted reflections from the model boundary. Last, we give elastic wave modeling examples for homogeneous and heterogeneous models to demonstrate the advantages of the proposed scheme. 展开更多
关键词 Implicit finite difference symmetric boundary condition high-order accuracy TRUNCATION absorbing boundary condition staggered grid numerical modeling
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High-order field theory and a weak Euler–Lagrange–Barut equation for classical relativistic particle-field systems
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作者 范培锋 陈强 +1 位作者 肖建元 于治 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第11期42-54,共13页
In both quantum and classical field systems,conservation laws such as the conservation of energy and momentum are widely regarded as fundamental properties.A broadly accepted approach to deriving conservation laws is ... In both quantum and classical field systems,conservation laws such as the conservation of energy and momentum are widely regarded as fundamental properties.A broadly accepted approach to deriving conservation laws is built using Noether's method.However,this procedure is still unclear for relativistic particle-field systems where particles are regarded as classical world lines.In the present study,we establish a general manifestly covariant or geometric field theory for classical relativistic particle-field systems.In contrast to quantum systems,where particles are viewed as quantum fields,classical relativistic particle-field systems present specific challenges.These challenges arise from two sides.The first comes from the mass-shell constraint.To deal with the mass-shell constraint,the Euler–Lagrange–Barut(ELB)equation is used to determine the particle's world lines in the four-dimensional(4D)Minkowski space.Besides,the infinitesimal criterion,which is a differential equation in formal field theory,is reconstructed by an integro-differential form.The other difficulty is that fields and particles depend on heterogeneous manifolds.To overcome this challenge,we propose using a weak version of the ELB equation that allows us to connect local conservation laws and continuous symmetries in classical relativistic particle-field systems.By applying a weak ELB equation to classical relativistic particle-field systems,we can systematically derive local conservation laws by examining the underlying symmetries of the system.Our proposed approach provides a new perspective on understanding conservation laws in classical relativistic particle-field systems. 展开更多
关键词 high-order field theory weak Euler-Lagrange-Barut equation infinitesimal criterion of symmetric condition Noether's theorem geometric conservation laws
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One-and Multi-dimensional CWENOZ Reconstructions for Implementing Boundary Conditions Without Ghost Cells
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作者 M.Semplice E.Travaglia G.Puppo 《Communications on Applied Mathematics and Computation》 2023年第1期143-169,共27页
We address the issue of point value reconstructions from cell averages in the context of third-order finite volume schemes,focusing in particular on the cells close to the boundaries of the domain.In fact,most techniq... We address the issue of point value reconstructions from cell averages in the context of third-order finite volume schemes,focusing in particular on the cells close to the boundaries of the domain.In fact,most techniques in the literature rely on the creation of ghost cells outside the boundary and on some form of extrapolation from the inside that,taking into account the boundary conditions,fills the ghost cells with appropriate values,so that a standard reconstruction can be applied also in the boundary cells.In Naumann et al.(Appl.Math.Comput.325:252–270.https://doi.org/10.1016/j.amc.2017.12.041,2018),motivated by the difficulty of choosing appropriate boundary conditions at the internal nodes of a network,a different technique was explored that avoids the use of ghost cells,but instead employs for the boundary cells a different stencil,biased towards the interior of the domain.In this paper,extending that approach,which does not make use of ghost cells,we propose a more accurate reconstruction for the one-dimensional case and a two-dimensional one for Cartesian grids.In several numerical tests,we compare the novel reconstruction with the standard approach using ghost cells. 展开更多
关键词 high-order finite volume schemes Boundary conditions without ghost cells Hyperbolic systems CWENOZ reconstruction Adaptive order reconstructions
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HIGH-ORDER LOCAL ABSORBING BOUNDARY CONDITIONS FOR HEAT EQUATION IN UNBOUNDED DOMAINS 被引量:1
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作者 Xiaonan Wu Jiwei Zhang 《Journal of Computational Mathematics》 SCIE CSCD 2011年第1期74-90,共17页
With the development of numerical methods the numerical computations require higher and higher accuracy. This paper is devoted to the high-order local absorbing boundary conditions (ABCs) for heat equation. We prove... With the development of numerical methods the numerical computations require higher and higher accuracy. This paper is devoted to the high-order local absorbing boundary conditions (ABCs) for heat equation. We proved that the coupled system yields a stable problem between the obtained high-order local ABCs and the partial differential equation in the computational domain. This method has been used widely in wave propagation models only recently. We extend the spirit of the methodology to parabolic ones, which will become a basis to design the local ABCs for a class of nonlinear PDEs. Some numerical tests show that the new treatment is very efficient and tractable. 展开更多
关键词 Heat equation high-order method Absorbing boundary conditions Parabolicproblems in unbounded domains.
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J-selfadjointness of a class of high-order differential operators with transmission conditions
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作者 Ji LI Meizhen XU 《Frontiers of Mathematics in China》 SCIE CSCD 2022年第6期1025-1035,共11页
This paper is to investigate the J-selfadjointness of a class of high-order complex coefficients differential operators with transmission conditions.Using the Lagrange bilinear form of J-symmetric differential equatio... This paper is to investigate the J-selfadjointness of a class of high-order complex coefficients differential operators with transmission conditions.Using the Lagrange bilinear form of J-symmetric differential equations,the definition of J-selfadjoint differential operators and the method of matrix representation,we prove that the operator is J-selfadjoint operator,and the eigenvectors and eigen-subspaces corresponding to different eigenvalues are C-orthogonal. 展开更多
关键词 high-order differential operator transmission conditions J-self-adjoint C-orthogonal
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Analysis of High-Order Absorbing Boundary Conditions for the Schrodinger Equation
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作者 Jiwei Zhang Zhizhong Sun +1 位作者 Xiaonan Wu Desheng Wang 《Communications in Computational Physics》 SCIE 2011年第8期742-766,共25页
The paper is concerned with the numerical solution of Schr¨odinger equations on an unbounded spatial domain.High-order absorbing boundary conditions for one-dimensional domain are derived,and the stability of the... The paper is concerned with the numerical solution of Schr¨odinger equations on an unbounded spatial domain.High-order absorbing boundary conditions for one-dimensional domain are derived,and the stability of the reduced initial boundary value problem in the computational interval is proved by energy estimate.Then a second order finite difference scheme is proposed,and the convergence of the scheme is established as well.Finally,numerical examples are reported to confirm our error estimates of the numerical methods. 展开更多
关键词 Schrodinger equation finite difference method high-order absorbing boundary condition CONVERGENCE
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The unified transform method to the high-order nonlinear Schrodinger equation with periodic initial condition
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作者 Leilei Liu Weiguo Zhang +1 位作者 Jian Xu Yuli Guo 《Communications in Theoretical Physics》 SCIE CAS CSCD 2022年第8期1-10,共10页
In this paper,we study the high-order nonlinear Schrodinger equation with periodic initial conditions via the unified transform method extended by Fokas and Lenells.For the high-order nonlinear Schrodinger equation,th... In this paper,we study the high-order nonlinear Schrodinger equation with periodic initial conditions via the unified transform method extended by Fokas and Lenells.For the high-order nonlinear Schrodinger equation,the initial value problem on the circle can be expressed in terms of the solution of a Riemann–Hilbert problem.The related jump matrix can be explicitly expressed based on the initial data alone.Furthermore,we present the explicit solution,which corresponds to a one-gap solution. 展开更多
关键词 periodic initial condition high-order nonlinear Schrodinger equation unified transform method Riemann–Hilbert problem
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我国证券保荐制度的外部制约与完善 被引量:10
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作者 伏军 程向梅 《河北法学》 CSSCI 北大核心 2006年第12期105-110,共6页
我国证券发行机制正处于由发行审核制向注册制过渡的阶段,现阶段的保荐制度既受到发行制度转轨进程的外部制约,又能有效推动这一进程。在发行制度转轨过程中,为了最大限度地发挥保荐制度的功效,除需转变监管理念和改革发行审核方式等制... 我国证券发行机制正处于由发行审核制向注册制过渡的阶段,现阶段的保荐制度既受到发行制度转轨进程的外部制约,又能有效推动这一进程。在发行制度转轨过程中,为了最大限度地发挥保荐制度的功效,除需转变监管理念和改革发行审核方式等制度外,还应当进一步完善保荐制度本身的各项具体制度,包括强化保荐人市场监管,平衡保荐人权利、义务与责任,加强行业自律监管等。 展开更多
关键词 保荐制度 发行审核 条件制约
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双重增发条件下上市公司盈余管理实证研究 被引量:4
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作者 张嘉兴 齐鲁光 《审计与经济研究》 CSSCI 北大核心 2015年第1期57-65,共9页
2006年和2008年证监会出台政策对增发新股公司的净资产收益率和现金分红均提出要求。以此为背景的实证研究发现,出于迎合政策中的双重增发条件目的,上市公司获取增发资格过程中为减少现金分红而实施了调减利润的盈余管理,而在增发当年... 2006年和2008年证监会出台政策对增发新股公司的净资产收益率和现金分红均提出要求。以此为背景的实证研究发现,出于迎合政策中的双重增发条件目的,上市公司获取增发资格过程中为减少现金分红而实施了调减利润的盈余管理,而在增发当年和增发下一年存在调增业绩的盈余管理,并运用了应计项目和真实活动两种盈余管理方式。双重增发条件下上市公司盈余管理目的和行为的转化应引起投资者、分析师、审计师及政策制定部门的重视。 展开更多
关键词 双重增发条件 增发新股 迎合政策 应计项目盈余管理 真实活动盈余管理 企业再融资
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欺诈发行股票、债券罪的危险犯性质与解释路径 被引量:13
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作者 高巍 《政治与法律》 CSSCI 北大核心 2018年第4期38-48,共11页
欺诈发行股票、债券罪的规范目的为证券市场公平性的保护,不应包括投资者利益的保护。立法者基于欺诈发行股票、债券行为的累积对证券市场公平性损害的经验性观察,拟制了欺诈发行股票债券行为的抽象危险性。为限制处罚范围,立法者设置... 欺诈发行股票、债券罪的规范目的为证券市场公平性的保护,不应包括投资者利益的保护。立法者基于欺诈发行股票、债券行为的累积对证券市场公平性损害的经验性观察,拟制了欺诈发行股票债券行为的抽象危险性。为限制处罚范围,立法者设置了欺诈发行股票、债券罪的罪量因素,其中,数额巨大和后果严重应当作为构成要件要素,严重情节不应作为构成要件要素。另外,对于欺诈发行股票、债券的基本行为方式,有必要在条文文义的范围根据规范目的进行限缩解释。"隐瞒重要事实"、"编造重大虚假内容"为评价性的规范构成要件要素,隐瞒和编造对象的"重要性"判断必须与证券市场的公平性有关。 展开更多
关键词 欺诈发行股票、债券罪 危险犯 罪量因素 限缩解释
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Pure quasi-P wave equation and numerical solution in 3D TTI media 被引量:3
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作者 张建敏 何兵寿 唐怀谷 《Applied Geophysics》 SCIE CSCD 2017年第1期125-132,191,共9页
Based on the pure quasi-P wave equation in transverse isotropic media with a vertical symmetry axis (VTI media), a quasi-P wave equation is obtained in transverse isotropic media with a tilted symmetry axis (TTI me... Based on the pure quasi-P wave equation in transverse isotropic media with a vertical symmetry axis (VTI media), a quasi-P wave equation is obtained in transverse isotropic media with a tilted symmetry axis (TTI media). This is achieved using projection transformation, which rotates the direction vector in the coordinate system of observation toward the direction vector for the coordinate system in which the z-component is parallel to the symmetry axis of the TTI media. The equation has a simple form, is easily calculated, is not influenced by the pseudo-shear wave, and can be calculated reliably when δ is greater than ε. The finite difference method is used to solve the equation. In addition, a perfectly matched layer (PML) absorbing boundary condition is obtained for the equation. Theoretical analysis and numerical simulation results with forward modeling prove that the equation can accurately simulate a quasi-P wave in TTI medium. 展开更多
关键词 TTI media the pure quasi-P wave equation high-order finite PML boundary conditions BP model
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Mixed Finite Element Method and Higher-Order Local Artificial Boundary Conditions for Exterior 3-D Poisson Equation
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作者 韩厚德 郑春雄 《Tsinghua Science and Technology》 SCIE EI CAS 2002年第3期228-234,共7页
The mixed finite element method is used to solve the exterior Poisson equations with higher-order local artificial boundary conditions in 3-D space. New unknowns are introduced to reduce the order of the derivatives ... The mixed finite element method is used to solve the exterior Poisson equations with higher-order local artificial boundary conditions in 3-D space. New unknowns are introduced to reduce the order of the derivatives of the unknown to two. The result is an equivalent mixed variational problem which was solved using bilinear finite elements. The primary advantage is that special finite elements are not needed on the adjacent layer of the artificial boundary for the higher-order derivatives. Error estimates are obtained for some local artificial boundary conditions with prescibed orders. A numerical example demonstrates the effectiveness of this method. 展开更多
关键词 artificial boundary high-order artificial boundary condition mixed finite element method
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A Third-Order Scheme for Numerical Fluxes to Guarantee Non-Negative Coefficients for Advection-Diffusion Equations
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作者 Katsuhiro Sakai Daishi Watabe 《American Journal of Computational Mathematics》 2011年第1期26-38,共13页
According to Godunov theorem for numerical calculations of advection equations, there exist no high-er-order schemes with constant positive difference coefficients in a family of polynomial schemes with an accuracy ex... According to Godunov theorem for numerical calculations of advection equations, there exist no high-er-order schemes with constant positive difference coefficients in a family of polynomial schemes with an accuracy exceeding the first-order. In case of advection-diffusion equations, so far there have been not found stable schemes with positive difference coefficients in a family of numerical schemes exceeding the second-order accuracy. We propose a third-order computational scheme for numerical fluxes to guarantee the non-negative difference coefficients of resulting finite difference equations for advection-diffusion equations. The present scheme is optimized so as to minimize truncation errors for the numerical fluxes while fulfilling the positivity condition of the difference coefficients which are variable depending on the local Courant number and diffusion number. The feature of the present optimized scheme consists in keeping the third-order accuracy anywhere without any numerical flux limiter by using the same stencil number as convemtional third-order shemes such as KAWAMURA and UTOPIA schemes. We extend the present method into multi-dimensional equations. Numerical experiments for linear and nonlinear advection-diffusion equations were performed and the present scheme’s applicability to nonlinear Burger’s equation was confirmed. 展开更多
关键词 NUMERICAL SCHEME NUMERICAL Analysis NUMERICAL Stability POSITIVITY condition ADVECTION-DIFFUSION EQUATION Advection EQUATION high-order SCHEME GODUNOV Theorem Burgers’ EQUATION
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Inverse Scattering Transform and Soliton Solutions for the Hirota Equation with N Distinct Arbitrary Order Poles 被引量:1
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作者 Xiaofan Zhang Shoufu Tian Jinjie Yang 《Advances in Applied Mathematics and Mechanics》 SCIE 2022年第4期893-913,共21页
We employ the Riemann-Hilbert(RH)method to study the Hirota equation with arbitrary order zero poles under zero boundary conditions.Through the spectral analysis,the asymptoticity,symmetry,and analysis of the Jost fun... We employ the Riemann-Hilbert(RH)method to study the Hirota equation with arbitrary order zero poles under zero boundary conditions.Through the spectral analysis,the asymptoticity,symmetry,and analysis of the Jost functions are obtained,which play a key role in constructing the RH problem.Then we successfully established the exact solution of the equation without reflection potential by solving the RH problem.Choosing some appropriate parameters of the resulting solutions,we further derive the soliton solutions with different order poles,including four cases of a fourthorder pole,two second-order poles,a third-order pole and a first-order pole,and four first-order points.Finally,the dynamical behavior of these solutions are analyzed via graphic analysis. 展开更多
关键词 The Hirota equation zero boundary condition Riemann-Hilbert problem high-order poles soliton solutions
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A Flexible Boundary Procedure for Hyperbolic Problems: Multiple Penalty Terms Applied in a Domain
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作者 Jan Nordstrom Qaisar Abbas +1 位作者 Brittany A.Erickson Hannes Frenander 《Communications in Computational Physics》 SCIE 2014年第7期541-570,共30页
A new weak boundary procedure for hyperbolic problems is presented.We consider high order finite difference operators of summation-by-parts form with weak boundary conditions and generalize that technique.The new boun... A new weak boundary procedure for hyperbolic problems is presented.We consider high order finite difference operators of summation-by-parts form with weak boundary conditions and generalize that technique.The new boundary procedure is applied near boundaries in an extended domain where data is known.We show how to raise the order of accuracy of the scheme,how to modify the spectrum of the resulting operator and how to construct non-reflecting properties at the boundaries.The new boundary procedure is cheap,easy to implement and suitable for all numerical methods,not only finite difference methods,that employ weak boundary conditions.Numerical results that corroborate the analysis are presented. 展开更多
关键词 Summation-by-parts weak boundary conditions penalty technique high-order accuracy finite difference schemes stability STEADY-STATE non-reflecting boundary conditions
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人身安全保护令核发条件的高阶化及消解
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作者 林洋 《私法》 2019年第1期364-382,共19页
《反家暴法》中人身安全保护令制度的适用率低,存在多方面的原因,但人身安全保护令核发条件的高阶化是基础性的原因。我国大陆并未采取英美法系和我国台湾地区立法中通常保护令和暂时保护令的分类,而是杂糅了两种类型的保护令。该种杂... 《反家暴法》中人身安全保护令制度的适用率低,存在多方面的原因,但人身安全保护令核发条件的高阶化是基础性的原因。我国大陆并未采取英美法系和我国台湾地区立法中通常保护令和暂时保护令的分类,而是杂糅了两种类型的保护令。该种杂糅实质是采取通常保护令的核发程序,同时采用暂时保护令的核发条件,造成我国人身安全保护令核发条件的高阶化。对比分析可知,通常保护令实质是行为给付的民事判决,而暂时保护令的实质是临时救济的裁定,两者在审理程序、核发条件等多方面存在本质差异,不能随意杂糅。因此,高阶化应对方式是对比大陆法系临时救济制度,以我国行为保全为基础,引入暂时保护令和通常保护令的分类,分别设置不同核发条件、审理程序和救济程序。 展开更多
关键词 适用率低 核发条件高阶化 暂时保护令
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