Local Multigrid in H（curl）

We consider H（curl, Ω）-elliptic variational problems on bounded Lipschitz polyhedra and their finite element Galerkin discretization by means of lowest order edge elements. We assume that the underlying tetrahedral mesh has been created by successive local mesh refinement, either by local uniform refinement with hanging nodes or bisection refinement. In this setting we develop a convergence theory for the the so-called local multigrid correction scheme with hybrid smoothing. We establish that its convergence rate is uniform with respect to the number of refinement steps. The proof relies on corresponding results for local multigrid in a H^1 （Ω）-context along with local discrete Helmholtz-type decompositions of the edge element space.     

含时div—curl引理的一个证明

本文中我们用Ｆｏｕｒｉｅｒ分析方法证明了含时的ｄｉｖ－ｃｕｒｌ引理。     

含时div－curl引理的一个证明

本文中我们用Ｆｏｕｒｉｅｒ分析方法证明了含时的ｄｉｖ－ｃｕｒｌ引理。     

PARALLEL AUXILIARY SPACE AMG FOR H（curl） PROBLEMS

In this paper we review a number of auxiliary space based preconditioners for the second order definite and semi-definite Maxwell problems discretized with the lowest order Nedelec finite elements. We discuss the parallel implementation of the most promising of these methods, the ones derived from the recent Hiptmair-Xu （HX） auxiliary space decomposition [Hiptmair and Xu, SIAM J. Numer. Anal., 45 （2007）, pp. 2483-2509]. An extensive set of numerical experiments demonstrate the scalability of our implementation on large-scale H（curl） problems.     

Sharp a priori estimates for div–curl systems in Heisenberg groups

In this paper we prove a family of inequalities for differential forms in Heisenberg groups H¹${\mathbb{H}}^1$ and H²${\mathbb{H}}^2$, that are the natural counterpart of a class of div–curl inequalities in de Rham?s complex proved by Lanzani & Stein and Bourgain & Brezis.     

Normal Currents: Structure, Duality Pairings and div–curl Lemmas

The paper gives a decomposition of a general normal r-dimensional current [5] into the sum of three measures of which the first is an r-dimensional rectifiable measure, the second is the Cantor part of the current, and the third is Lebesgue absolutely continuous. This is analogous to the well-known decomposition of the derivative of a function of bounded variation into the jump, Cantor, and absolutely continuous parts; in fact the last is a special case of the result for (n–1)-dimensional normal currents. Further, Whitney’s cap product [15] is recast in the language of the approach to flat chains by Federer [5] and a special case (viz., currents of dimension n – 1) is shown to be closely related to the measure-valued duality pairings between vector measures with curl a measure and L^∞ vectorfields with L^∞ divergence as established by Anzellotti [2] and Kohn & Témam [6]. Finally, the cap product is shown to be jointly weak* continuous in the two factors of the product in a way similar to the compensated compactness theory; in the cases of (n – 1)-dimensional objects this reduces to results closely related to the div–curl lemmas of the standard compensated compactness theory. Received: June 2007     

太阳系界面动态磁场问题的H(curl,Ω)有限元最优误差估计

本文利用具有最优插值逼近的界面棱边元来逼近太阳系界面动态磁场问题,采用界面对齐的三角剖分对区域进行划分且跳转接口被δ-带包围.利用界面棱边元的性质,得到了关于动态磁场的最优误差估计,收敛结果为O(τ+h),其中τ和h分别是时间和空间方向的剖分步长.最后,对太阳系界面模型的动态磁场进行了数值模拟.     

Decay of solutions of a limiting form of Ginzburg–Landau systems involving curl

In this note, we study a semilinear system involving the operator curl in an exterior domain in R³${\mathbb{R}}^3$, which is the limiting form of the Ginzburg–Landau model for superconductors in three dimensions for a large value of the Ginzburg–Landau parameter. We prove that this problem has a smooth solution, and it decays exponentially at infinity.     

ON THE CONSTRUCTION OF WELL-CONDITIONED HIERARCHICAL BASES FOR TETRAHEDRAL H（curl）-CONFORMING NEDELEC ELEMENT

A partially orthonormal basis is constructed with better conditioning properties for tetrahedral H(curl)-conforming Nédélec elements.The shape functions are cla...     

Convergence analysis of finite element methods for H(curl; Ω)-elliptic interface problems

In this article we investigate the analysis of a finite element method for solving H(curl; ??)-elliptic interface problems in general three-dimensional polyhedral domains with smooth interfaces. The continuous problems are discretized by means of the first family of lowest order Nédélec H(curl; ??)-conforming finite elements on a family of tetrahedral meshes which resolve the smooth interface in the sense of sufficient approximation in terms of a parameter ?? that quantifies the mismatch between the smooth interface and the triangulation. Optimal error estimates in the H(curl; ??)-norm are obtained for the first time. The analysis is based on a ??-strip argument, a new extension theorem for H ¹(curl; ??)-functions across smooth interfaces, a novel non-standard interface-aware interpolation operator, and a perturbation argument for degrees of freedom for H(curl; ??)-conforming finite elements. Numerical tests are presented to verify the theoretical predictions and confirm the optimal order convergence of the numerical solution.     

一种求解H(curl)型椭圆问题的非重叠DDM预条件子

本文对一类H(curl)型椭圆问题的线性棱有限元方程,构造了一种具有简单粗空间的非重叠区域分解型预条件子.在系数为常数的情形下,严格证明了相应的预条件系统的条件数为O(log2d/h),即是渐近最优的.数值实验验证了理论结果的正确性,并说明该预条件子对大跳系数的情形也是有效的.