引入局部条件并半格 (简记为 L cusl)及其理想完备化等概念 .证明了 :任一代数 L domain的紧元集是 L cusl;任一代数 L domain是其紧元集赋予 Alexandrov拓扑时的 Sober化 ;任一 L cusl的理想完备化是代数 L domain,从而得到了代数 L do...引入局部条件并半格 (简记为 L cusl)及其理想完备化等概念 .证明了 :任一代数 L domain的紧元集是 L cusl;任一代数 L domain是其紧元集赋予 Alexandrov拓扑时的 Sober化 ;任一 L cusl的理想完备化是代数 L domain,从而得到了代数 L domain的表示定理 .还证明了 Scott连续映射为态射的代数 L domain范畴为 L cusl与单调映射作成的范畴的反射子范畴 .展开更多
Most researches focused on the analytical stabilized algorithm for the modular simulation of single domain, e.g., pure mechanical systems. Only little work has been performed on the problem of multi-domain simulation ...Most researches focused on the analytical stabilized algorithm for the modular simulation of single domain, e.g., pure mechanical systems. Only little work has been performed on the problem of multi-domain simulation stability influenced by algebraic loops. In this paper, the algebraic loop problem is studied by a composite simulation method to reveal the internal relationship between simulation stability and system topologies and simulation unit models. A stability criterion of multi-domain composite simulation is established, and two algebraic loop compensation algorithms are proposed using numerical iteration and approximate function in multi-domain simulation. The numerical stabilized algorithm is the Newton method for the solution of the set of nonlinear equations, and it is used here in simulation of the system composed of mechanical system and hydraulic system. The approximate stabilized algorithm is the construction of response surface for inputs and outputs of unknown unit model, and it is utilized here in simulation of the system composed of forging system, mechanical and hydraulic system. The effectiveness of the algorithms is verified by a case study of multi-domain simulation for forging system composed of thermoplastic deformation of workpieces, mechanical system and hydraulic system of a manipulator. The system dynamics simulation results show that curves of motion and force are continuous and convergent. This paper presents two algorithms, which are applied to virtual reality simulation of forging process in a simulation platform for a manipulator, and play a key role in simulation efficiency and stability.展开更多
One of the reasons for the great success of the finite element method is its versatility to deal with different types of geometries. This is particularly true of problems posed in curved domains. Nevertheless it is we...One of the reasons for the great success of the finite element method is its versatility to deal with different types of geometries. This is particularly true of problems posed in curved domains. Nevertheless it is well-known that, for standard variational formulations, the optimal approximation properties known to hold for polytopic domains are lost, if meshes consisting of ordinary elements are still used in the case of curved domains. That is why method’s isoparametric version for meshes consisting of curved triangles or tetrahedra has been widely employed, especially in case Dirichlet boundary conditions are prescribed all over a curved boundary. However, besides geometric inconveniences, the isoparametric technique helplessly requires the manipulation of rational functions and the use of numerical integration. In this work we consider a simple alternative that bypasses these drawbacks, without eroding qualitative approximation properties. More specifically we work with a variational formulation leading to high order finite element methods based only on polynomial algebra, since they do not require the use of curved elements. Application of the new approach to Lagrange methods of arbitrary order illustrates its potential to take the best advantage of finite-element discretizations in the solution of wide classes of problems posed in curved domains.展开更多
In this article, the author discusses the dimension of holomorphic automorphism groups on hyperbolic Reirihardt domains. and classifies those hyperbolic Reinhardt domains whose automorphism group has prescribed dimens...In this article, the author discusses the dimension of holomorphic automorphism groups on hyperbolic Reirihardt domains. and classifies those hyperbolic Reinhardt domains whose automorphism group has prescribed dimension n2 - 2 (where n is the dimension of domain).展开更多
文摘引入局部条件并半格 (简记为 L cusl)及其理想完备化等概念 .证明了 :任一代数 L domain的紧元集是 L cusl;任一代数 L domain是其紧元集赋予 Alexandrov拓扑时的 Sober化 ;任一 L cusl的理想完备化是代数 L domain,从而得到了代数 L domain的表示定理 .还证明了 Scott连续映射为态射的代数 L domain范畴为 L cusl与单调映射作成的范畴的反射子范畴 .
基金supported by National Natural Science Foundation of China(Grant Nos.51075259,51121063,51305256)National Basic Research Program of China(973 Program,Grant No.2006CB705400)
文摘Most researches focused on the analytical stabilized algorithm for the modular simulation of single domain, e.g., pure mechanical systems. Only little work has been performed on the problem of multi-domain simulation stability influenced by algebraic loops. In this paper, the algebraic loop problem is studied by a composite simulation method to reveal the internal relationship between simulation stability and system topologies and simulation unit models. A stability criterion of multi-domain composite simulation is established, and two algebraic loop compensation algorithms are proposed using numerical iteration and approximate function in multi-domain simulation. The numerical stabilized algorithm is the Newton method for the solution of the set of nonlinear equations, and it is used here in simulation of the system composed of mechanical system and hydraulic system. The approximate stabilized algorithm is the construction of response surface for inputs and outputs of unknown unit model, and it is utilized here in simulation of the system composed of forging system, mechanical and hydraulic system. The effectiveness of the algorithms is verified by a case study of multi-domain simulation for forging system composed of thermoplastic deformation of workpieces, mechanical system and hydraulic system of a manipulator. The system dynamics simulation results show that curves of motion and force are continuous and convergent. This paper presents two algorithms, which are applied to virtual reality simulation of forging process in a simulation platform for a manipulator, and play a key role in simulation efficiency and stability.
文摘One of the reasons for the great success of the finite element method is its versatility to deal with different types of geometries. This is particularly true of problems posed in curved domains. Nevertheless it is well-known that, for standard variational formulations, the optimal approximation properties known to hold for polytopic domains are lost, if meshes consisting of ordinary elements are still used in the case of curved domains. That is why method’s isoparametric version for meshes consisting of curved triangles or tetrahedra has been widely employed, especially in case Dirichlet boundary conditions are prescribed all over a curved boundary. However, besides geometric inconveniences, the isoparametric technique helplessly requires the manipulation of rational functions and the use of numerical integration. In this work we consider a simple alternative that bypasses these drawbacks, without eroding qualitative approximation properties. More specifically we work with a variational formulation leading to high order finite element methods based only on polynomial algebra, since they do not require the use of curved elements. Application of the new approach to Lagrange methods of arbitrary order illustrates its potential to take the best advantage of finite-element discretizations in the solution of wide classes of problems posed in curved domains.
基金Supported by the National Natural Science Foundation of China (10501036)the Natural Science Foundation of Fujian Province of China (Z0511003).
文摘In this article, the author discusses the dimension of holomorphic automorphism groups on hyperbolic Reirihardt domains. and classifies those hyperbolic Reinhardt domains whose automorphism group has prescribed dimension n2 - 2 (where n is the dimension of domain).
