In this article, Richardson extrapolation technique is employed to investigate the local ultraconvergence properties of Lagrange finite element method using piecewise polynomials of degrees () for the second order elliptic problem with inhomogeneous boundary. A sequence of special graded partition are proposed and a new interpolation operator is introduced to achieve order local ultraconvergence for the displacement and derivative.

中文翻译：

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非齐次边界条件椭圆问题的理查森外推法的超收敛

在本文中，Richardson 外推技术被用于研究使用分段多项式( )的拉格朗日有限元方法对具有非齐次边界的二阶椭圆问题的局部超收敛特性。提出了一系列特殊的分级划分，并引入了一种新的插值算子来实现位移和导数的阶局部超收敛。