In this paper, we introduce a domain decomposition method with non-matching grids for solving Dirichlet exterior boundary problems by coupling of finite element method (FEM) and natural boundary element method(BEM...In this paper, we introduce a domain decomposition method with non-matching grids for solving Dirichlet exterior boundary problems by coupling of finite element method (FEM) and natural boundary element method(BEM). We first derive the optimal energy error estimate of the nonconforming approximation generated by this method. Then we apply a Dirichlet-Neumann(D-N) alternating algorithm to solve the coupled discrete system. It will be shown that such iterative method possesses the optimal convergence. The numerical experiments testify our theoretical results.展开更多
Several malfunctions of the shield tunneling machine (STM) caused by structural interference have been encountered in actual tunnel excavation. This paper is focusing on providing an effective method to avoid the st...Several malfunctions of the shield tunneling machine (STM) caused by structural interference have been encountered in actual tunnel excavation. This paper is focusing on providing an effective method to avoid the structural interference based on making the reachable and the required workspaces of the thrust system match each other. The main structure of the thrust mechanism is analyzed, and coordinate systems are built up to describe the pose and workspace of the thrust mechanism. Constraint conditions are derived and the formulation of each constraint condition is carried out to facilitate the analysis of the reachable workspace of the thrust mechanism. Meanwhile, a reachable workspace determination algorithm is introduced based on interval analysis method. The mathematical model for determining the required workspace of the thrust mechanism is presented based on the analysis of the process when the STM excavates along a specific tunnel axis. Two applications are included to show how to avoid these problems by choosing reasonable parameters of the designed tunnel axis and the key structural parameters of the thrust mechanism based on workspace matching.展开更多
基金The work of this author was supported by Natural Science Foundation of China(G10371129) The work of this author was supported by the National Basic Research Program of China under the grant G19990328,2005CB321701 the National Natural Science Foundation of China.
文摘In this paper, we introduce a domain decomposition method with non-matching grids for solving Dirichlet exterior boundary problems by coupling of finite element method (FEM) and natural boundary element method(BEM). We first derive the optimal energy error estimate of the nonconforming approximation generated by this method. Then we apply a Dirichlet-Neumann(D-N) alternating algorithm to solve the coupled discrete system. It will be shown that such iterative method possesses the optimal convergence. The numerical experiments testify our theoretical results.
基金supported by the National Natural Science Foundation of China (Grant No. 51605071)National Basic Research Program of China (Grant No. 2013CB035400)the special grade of the China Postdoctoral Science Foundation (Grant No. 2016T90218)
文摘Several malfunctions of the shield tunneling machine (STM) caused by structural interference have been encountered in actual tunnel excavation. This paper is focusing on providing an effective method to avoid the structural interference based on making the reachable and the required workspaces of the thrust system match each other. The main structure of the thrust mechanism is analyzed, and coordinate systems are built up to describe the pose and workspace of the thrust mechanism. Constraint conditions are derived and the formulation of each constraint condition is carried out to facilitate the analysis of the reachable workspace of the thrust mechanism. Meanwhile, a reachable workspace determination algorithm is introduced based on interval analysis method. The mathematical model for determining the required workspace of the thrust mechanism is presented based on the analysis of the process when the STM excavates along a specific tunnel axis. Two applications are included to show how to avoid these problems by choosing reasonable parameters of the designed tunnel axis and the key structural parameters of the thrust mechanism based on workspace matching.