Symplectic self-adjointness of Hamiltonian operator matrices is studied, which is important to symplectic elasticity and optimal control. For the cases of diagonal domain and off-diagonal domain, necessary and suffici...Symplectic self-adjointness of Hamiltonian operator matrices is studied, which is important to symplectic elasticity and optimal control. For the cases of diagonal domain and off-diagonal domain, necessary and sufficient conditions are shown. The proofs use Frobenius-Schur factorizations of unbounded operator matrices.Under additional assumptions, sufficient conditions based on perturbation method are obtained. The theory is applied to a problem in symplectic elasticity.展开更多
Symplectic self-adjointness of infinite dimensional Hamiltonian operators is studied, the necessary and sufficient conditions are given. Using the relatively bounded perturbation, the sufficient conditions about sympl...Symplectic self-adjointness of infinite dimensional Hamiltonian operators is studied, the necessary and sufficient conditions are given. Using the relatively bounded perturbation, the sufficient conditions about symplectic self-adjointness are shown.展开更多
Symmetric and symplectic methods are classical notions in the theory of numerical methods for solving ordinary differential equations.They can generate numerical flows that respectively preserve the symmetry and sympl...Symmetric and symplectic methods are classical notions in the theory of numerical methods for solving ordinary differential equations.They can generate numerical flows that respectively preserve the symmetry and symplecticity of the continuous flows in the phase space.This article is mainly concerned with the symmetric-adjoint and symplectic-adjoint Runge-Kutta methods as well as their applications.It is a continuation and an extension of the study in[14],where the authors introduced the notion of symplectic-adjoint method of a Runge-Kutta method and provided a simple way to construct symplectic partitioned Runge-Kutta methods via the symplectic-adjoint method.In this paper,we provide a more comprehensive and systematic study on the properties of the symmetric-adjoint and symplecticadjoint Runge-Kutta methods.These properties reveal some intrinsic connections among some classical Runge-Kutta methods.Moreover,those properties can be used to significantly simplify the order conditions and hence can be applied to the construction of high-order Runge-Kutta methods.As a specific and illustrating application,we construct a novel class of explicit Runge-Kutta methods of stage 6 and order 5.Finally,with the help of symplectic-adjoint method,we thereby obtain a new simple proof of the nonexistence of explicit Runge-Kutta method with stage 5 and order 5.展开更多
By using the discrete variational method,we study the numerical method of the general nonholonomic system in the generalized Birkhoffian framework,and construct a numerical method of generalized Birkhoffian equations ...By using the discrete variational method,we study the numerical method of the general nonholonomic system in the generalized Birkhoffian framework,and construct a numerical method of generalized Birkhoffian equations called a self-adjoint-preserving algorithm.Numerical results show that it is reasonable to study the nonholonomic system by the structure-preserving algorithm in the generalized Birkhoffian framework.展开更多
Non-self-adjoint quasi-differential expression M and its formal adjoint M＋may generate nonsymmetric ordinary differential operators. Although minimal operators T0, T＋0 generated by M, M＋are not symmetric, they form...Non-self-adjoint quasi-differential expression M and its formal adjoint M＋may generate nonsymmetric ordinary differential operators. Although minimal operators T0, T＋0 generated by M, M＋are not symmetric, they form an adjoint pair. In this paper, author studies regularly solvable operators with respect to the adjoint pair T0, T＋0 in two kinds of conditions and give their geometry description in the corresponding ways.展开更多
Non-self-adjoint dynamical systems, e.g., nonholonomic systems, can admit an almost Poisson structure, which is formulated by a kind of Poisson bracket satisfying the usual properties except for the Jacobi identity. A...Non-self-adjoint dynamical systems, e.g., nonholonomic systems, can admit an almost Poisson structure, which is formulated by a kind of Poisson bracket satisfying the usual properties except for the Jacobi identity. A general theory of the almost Poisson structure is investigated based on a decompo- sition of the bracket into a sum of a Poisson one and an almost Poisson one. The corresponding rela- tion between Poisson structure and symplectic structure is proved, making use of Jacobiizer and symplecticizer. Based on analysis of pseudo-symplectic structure of constraint submanifold of Chaplygin’s nonholonomic systems, an almost Poisson bracket for the systems is constructed and decomposed into a sum of a canonical Poisson one and an almost Poisson one. Similarly, an almost Poisson structure, which can be decomposed into a sum of canonical one and an almost "Lie-Poisson" one, is also constructed on an affine space with torsion whose autoparallels are utilized to describe the free motion of some non-self-adjoint systems. The decomposition of the almost Poisson bracket di- rectly leads to a decomposition of a dynamical vector field into a sum of usual Hamiltionian vector field and an almost Hamiltonian one, which is useful to simplifying the integration of vector fields.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.11371185,11101200 and 11361034)Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20111501110001)+1 种基金Major Subject of Natural Science Foundation of Inner Mongolia of China(Grant No.2013ZD01)Natural Science Foundation of Inner Mongolia of China(Grant No.2012MS0105)
文摘Symplectic self-adjointness of Hamiltonian operator matrices is studied, which is important to symplectic elasticity and optimal control. For the cases of diagonal domain and off-diagonal domain, necessary and sufficient conditions are shown. The proofs use Frobenius-Schur factorizations of unbounded operator matrices.Under additional assumptions, sufficient conditions based on perturbation method are obtained. The theory is applied to a problem in symplectic elasticity.
基金Supported by NNSF of China(Grant Nos.11761029 and 11561048)NSF of Inner Mongolia(Grant No.2015MS0116)Natural Science Foundation of Hetao College(Grant No.HYZY201702)
文摘Symplectic self-adjointness of infinite dimensional Hamiltonian operators is studied, the necessary and sufficient conditions are given. Using the relatively bounded perturbation, the sufficient conditions about symplectic self-adjointness are shown.
基金supported by the NSF of China(No.11771436)The work of S.Gan was supported by the NSF of China,No.11971488+1 种基金The work of H.Liu was supported by the Hong Kong RGC General Research Funds,12301218,12302919 and 12301420The work of Z.Shang was supported by the NSF of China,No.11671392.
文摘Symmetric and symplectic methods are classical notions in the theory of numerical methods for solving ordinary differential equations.They can generate numerical flows that respectively preserve the symmetry and symplecticity of the continuous flows in the phase space.This article is mainly concerned with the symmetric-adjoint and symplectic-adjoint Runge-Kutta methods as well as their applications.It is a continuation and an extension of the study in[14],where the authors introduced the notion of symplectic-adjoint method of a Runge-Kutta method and provided a simple way to construct symplectic partitioned Runge-Kutta methods via the symplectic-adjoint method.In this paper,we provide a more comprehensive and systematic study on the properties of the symmetric-adjoint and symplecticadjoint Runge-Kutta methods.These properties reveal some intrinsic connections among some classical Runge-Kutta methods.Moreover,those properties can be used to significantly simplify the order conditions and hence can be applied to the construction of high-order Runge-Kutta methods.As a specific and illustrating application,we construct a novel class of explicit Runge-Kutta methods of stage 6 and order 5.Finally,with the help of symplectic-adjoint method,we thereby obtain a new simple proof of the nonexistence of explicit Runge-Kutta method with stage 5 and order 5.
基金Project Supported by National Natural Science Foundation of China(No.11371185,11361034)Major Subject of Natural Science Foundation of Inner Mongolia of China(No.2013ZD01)~~
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11472124,11572145,11202090,and 11301350)the Doctor Research Start-up Fund of Liaoning Province,China(Grant No.20141050)+1 种基金the China Postdoctoral Science Foundation(Grant No.2014M560203)the General Science and Technology Research Plans of Liaoning Educational Bureau,China(Grant No.L2013005)
文摘By using the discrete variational method,we study the numerical method of the general nonholonomic system in the generalized Birkhoffian framework,and construct a numerical method of generalized Birkhoffian equations called a self-adjoint-preserving algorithm.Numerical results show that it is reasonable to study the nonholonomic system by the structure-preserving algorithm in the generalized Birkhoffian framework.
文摘Non-self-adjoint quasi-differential expression M and its formal adjoint M＋may generate nonsymmetric ordinary differential operators. Although minimal operators T0, T＋0 generated by M, M＋are not symmetric, they form an adjoint pair. In this paper, author studies regularly solvable operators with respect to the adjoint pair T0, T＋0 in two kinds of conditions and give their geometry description in the corresponding ways.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10872084, 10472040)the Outstanding Young Talents Training Fund of Liaoning Province of China (Grant No. 3040005)the Research Program of Higher Educa-tion of Liaoning Province of China (Grant No. 2008S098)
文摘Non-self-adjoint dynamical systems, e.g., nonholonomic systems, can admit an almost Poisson structure, which is formulated by a kind of Poisson bracket satisfying the usual properties except for the Jacobi identity. A general theory of the almost Poisson structure is investigated based on a decompo- sition of the bracket into a sum of a Poisson one and an almost Poisson one. The corresponding rela- tion between Poisson structure and symplectic structure is proved, making use of Jacobiizer and symplecticizer. Based on analysis of pseudo-symplectic structure of constraint submanifold of Chaplygin’s nonholonomic systems, an almost Poisson bracket for the systems is constructed and decomposed into a sum of a canonical Poisson one and an almost Poisson one. Similarly, an almost Poisson structure, which can be decomposed into a sum of canonical one and an almost "Lie-Poisson" one, is also constructed on an affine space with torsion whose autoparallels are utilized to describe the free motion of some non-self-adjoint systems. The decomposition of the almost Poisson bracket di- rectly leads to a decomposition of a dynamical vector field into a sum of usual Hamiltionian vector field and an almost Hamiltonian one, which is useful to simplifying the integration of vector fields.
