Recently,inspired by a modified generalized shift-splitting iteration method for complex symmetric linear systems,we propose two variants of the modified generalized shift-splitting iteration(MGSS)methods for solving ...Recently,inspired by a modified generalized shift-splitting iteration method for complex symmetric linear systems,we propose two variants of the modified generalized shift-splitting iteration(MGSS)methods for solving com-plex symmetric linear systems.One is a parameterized MGSS iteration method and the other is a modified parameterized MGSS iteration method.We prove that the proposed methods are convergent under appropriate constraints on the parameters.In addition,we also give the eigenvalue distributions of differ-ent preconditioned matrices to verify the effectiveness of the preconditioners proposed in this paper.展开更多
In this article,we study complex symmetric Toeplitz operators on the Bergman space and the pluriharmonic Bergman space in several variables.Surprisingly,the necessary and sufficient conditions for Toeplitz operators t...In this article,we study complex symmetric Toeplitz operators on the Bergman space and the pluriharmonic Bergman space in several variables.Surprisingly,the necessary and sufficient conditions for Toeplitz operators to be complex symmetric on these two spaces with certain conjugations are just the same.Also,some interesting symmetry properties of complex symmetric Toeplitz operators are obtained.展开更多
We propose to study the accelerating expansion of the universe in the double complex symmetric gravitational theory （DCSGT）. The universe we live in is taken as the real part of the whole spacetime MC^4（J）, which ...We propose to study the accelerating expansion of the universe in the double complex symmetric gravitational theory （DCSGT）. The universe we live in is taken as the real part of the whole spacetime MC^4（J）, which is double complex. By introducing the spatially flat FRW metric, not only the double Friedmann equations but also the two constraint conditions py = 0 and J^2 = 1 are obtained. Farthermore, using parametric DL（z） ansatz, we reconstruct the ω/（z） and V（Ф） for dark energy from real observational data. We find that in the two cases of J = i, pJ = 0, and J = ε, pJ≠0, the corresponding equations of state ω＇（z） remain close to -1 at present （z = 0） and change from below -1 to above -1. The results illustrate that the whole spacetime, i.e. the double complex spacetime MC^4（J）, may be either ordinary complex （J = i, pJ = 0） or hyperbolic complex （J = ε, pJ≠ 0）. And the fate of the universe would be Big Rip in the future.展开更多
For a conjugation C on a separable,complex Hilbert space H,the set S_(C) of Csymmetric operators on H forms a weakly closed,selfadjoint,Jordan operator algebra.In this paper,the authors study S_(C) in comparison with ...For a conjugation C on a separable,complex Hilbert space H,the set S_(C) of Csymmetric operators on H forms a weakly closed,selfadjoint,Jordan operator algebra.In this paper,the authors study S_(C) in comparison with the algebra B(H)of all bounded linear operators on H,and obtain S_(C)-analogues of some classical results concerning B(H).The authors determine the Jordan ideals of S_(C) and their dual spaces.Jordan automorphisms of S_(C) are classified.The authors determine the spectra of Jordan multiplication operators on S_(C) and their different parts.It is proved that those Jordan invertible ones constitute a dense,path connected subset of S_(C).展开更多
Let C be a conjugation on a separable complex Hilbert space H.An operator T on H is said to be C-symmetric if CTC=-T^(*),and T is said to be Cskew symmetric if CTC=-T^(*).It is proved in this paper that each C-skew sy...Let C be a conjugation on a separable complex Hilbert space H.An operator T on H is said to be C-symmetric if CTC=-T^(*),and T is said to be Cskew symmetric if CTC=-T^(*).It is proved in this paper that each C-skew symmetric operator can be written as the sum of two commutators of C-symmetric operators.展开更多
In this paper, we present a large-update primal-dual interior-point method for symmetric cone optimization（SCO） based on a new kernel function, which determines both search directions and the proximity measure betwe...In this paper, we present a large-update primal-dual interior-point method for symmetric cone optimization（SCO） based on a new kernel function, which determines both search directions and the proximity measure between the iterate and the center path. The kernel function is neither a self-regular function nor the usual logarithmic kernel function. Besides, by using Euclidean Jordan algebraic techniques, we achieve the favorable iteration complexity O（ √r（1/2）（log r）^2 log（r/ ε））, which is as good as the convex quadratic semi-definite optimization analogue.展开更多
This paper studies a class of weighted composition operators and their spectrum on the Fock space. As an application, bounded self-adjoint, a class of complex symmetric weighted composition operators on the Fock space...This paper studies a class of weighted composition operators and their spectrum on the Fock space. As an application, bounded self-adjoint, a class of complex symmetric weighted composition operators on the Fock space are characterized.展开更多
Structural, electronic, and magnetic behaviors of 5d transition metal（TM） atom substituted divacancy（DV） graphene are investigated using first-principles calculations. Different 5d TM atoms（Hf, Ta, W, Re, Os, Ir,...Structural, electronic, and magnetic behaviors of 5d transition metal（TM） atom substituted divacancy（DV） graphene are investigated using first-principles calculations. Different 5d TM atoms（Hf, Ta, W, Re, Os, Ir, and Pt） are embedded in graphene, these impurity atoms replace 2 carbon atoms in the graphene sheet. It is revealed that the charge transfer occurs from 5d TM atoms to the graphene layer. Hf, Ta, and W substituted graphene structures exhibit a finite band gap at high symmetric K-point in their spin up and spin down channels with 0.783 μB, 1.65 μB, and 1.78 μB magnetic moments,respectively. Ir and Pt substituted graphene structures display indirect band gap semiconductor behavior. Interestingly, Os substituted graphene shows direct band gap semiconductor behavior having a band gap of approximately 0.4 e V in their spin up channel with 1.5 μB magnetic moment. Through density of states（DOS） analysis, we can predict that d orbitals of 5d TM atoms could be responsible for introducing ferromagnetism in the graphene layer. We believe that our obtained results provide a new route for potential applications of dilute magnetic semiconductors and half-metals in spintronic devices by employing 5d transition metal atom-doped graphene complexes.展开更多
The Modified Hermitian and skew-Hermitian splitting （MHSS） iteration method was presented and studied by Bai, Benzi and Chen （Computing, 87（2010）, 93-111） for solving a class of complex symmetric linear systems....The Modified Hermitian and skew-Hermitian splitting （MHSS） iteration method was presented and studied by Bai, Benzi and Chen （Computing, 87（2010）, 93-111） for solving a class of complex symmetric linear systems. In this paper, using the properties of Toeplitz matrix, we propose a class of structured MHSS iteration methods for solving the complex Toeplitz linear system. Theoretical analysis shows that the structured MHSS iteration method is unconditionally convergent to the exact solution. When the MHSS iteration method is used directly to complex symmetric Toeplitz linear systems, the computational costs can be considerately reduced by use of Toeplitz structure. Finally, numerical ex- periments show that the structured MHSS iteration method and the structured MHSS preconditioner are efficient for solving the complex Toeplitz linear system.展开更多
An operator T on a separable,infinite dimensional,complex Hilbert space H is called conjugate normal if C|T|C=|T^(*)| for some conjugate linear,isometric involution C on H.This paper focuses on the invariance of conju...An operator T on a separable,infinite dimensional,complex Hilbert space H is called conjugate normal if C|T|C=|T^(*)| for some conjugate linear,isometric involution C on H.This paper focuses on the invariance of conjugate normality under similarity.Given an operator T,we prove that every operator A similar to T is conjugate normal if and only if there exist complex numbersλ_(1),λ_(2)such that(T-λ_(1))(T-λ_(2))=0.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12371378)by the Natural Science Foundation of Fujian Province(Grant Nos.2024J01980,2024J08242).
文摘Recently,inspired by a modified generalized shift-splitting iteration method for complex symmetric linear systems,we propose two variants of the modified generalized shift-splitting iteration(MGSS)methods for solving com-plex symmetric linear systems.One is a parameterized MGSS iteration method and the other is a modified parameterized MGSS iteration method.We prove that the proposed methods are convergent under appropriate constraints on the parameters.In addition,we also give the eigenvalue distributions of differ-ent preconditioned matrices to verify the effectiveness of the preconditioners proposed in this paper.
基金supported in part by the National Natural Science Foundation of China(11201331,11771323)。
文摘In this article,we study complex symmetric Toeplitz operators on the Bergman space and the pluriharmonic Bergman space in several variables.Surprisingly,the necessary and sufficient conditions for Toeplitz operators to be complex symmetric on these two spaces with certain conjugations are just the same.Also,some interesting symmetry properties of complex symmetric Toeplitz operators are obtained.
基金The project supported by National Natural Science Foundation of China under Grant No. 10573004
文摘We propose to study the accelerating expansion of the universe in the double complex symmetric gravitational theory （DCSGT）. The universe we live in is taken as the real part of the whole spacetime MC^4（J）, which is double complex. By introducing the spatially flat FRW metric, not only the double Friedmann equations but also the two constraint conditions py = 0 and J^2 = 1 are obtained. Farthermore, using parametric DL（z） ansatz, we reconstruct the ω/（z） and V（Ф） for dark energy from real observational data. We find that in the two cases of J = i, pJ = 0, and J = ε, pJ≠0, the corresponding equations of state ω＇（z） remain close to -1 at present （z = 0） and change from below -1 to above -1. The results illustrate that the whole spacetime, i.e. the double complex spacetime MC^4（J）, may be either ordinary complex （J = i, pJ = 0） or hyperbolic complex （J = ε, pJ≠ 0）. And the fate of the universe would be Big Rip in the future.
基金supported by the National Natural Science Foundation of China(Nos.12401149,12171195)the National Key Research and Development Program of China(No.2020YFA0714101).
文摘For a conjugation C on a separable,complex Hilbert space H,the set S_(C) of Csymmetric operators on H forms a weakly closed,selfadjoint,Jordan operator algebra.In this paper,the authors study S_(C) in comparison with the algebra B(H)of all bounded linear operators on H,and obtain S_(C)-analogues of some classical results concerning B(H).The authors determine the Jordan ideals of S_(C) and their dual spaces.Jordan automorphisms of S_(C) are classified.The authors determine the spectra of Jordan multiplication operators on S_(C) and their different parts.It is proved that those Jordan invertible ones constitute a dense,path connected subset of S_(C).
基金partly supported by the National Natural Science Foundation of China(Grant No.12i7195)by the National Key R&D Program(Grant No.2020YFA0714101).
文摘Let C be a conjugation on a separable complex Hilbert space H.An operator T on H is said to be C-symmetric if CTC=-T^(*),and T is said to be Cskew symmetric if CTC=-T^(*).It is proved in this paper that each C-skew symmetric operator can be written as the sum of two commutators of C-symmetric operators.
基金Supported by the Natural Science Foundation of Hubei Province(2008CDZD47)
文摘In this paper, we present a large-update primal-dual interior-point method for symmetric cone optimization（SCO） based on a new kernel function, which determines both search directions and the proximity measure between the iterate and the center path. The kernel function is neither a self-regular function nor the usual logarithmic kernel function. Besides, by using Euclidean Jordan algebraic techniques, we achieve the favorable iteration complexity O（ √r（1/2）（log r）^2 log（r/ ε））, which is as good as the convex quadratic semi-definite optimization analogue.
基金Supported by the National Natural Science Foundation of China(Grant Nos.1120127411471189)
文摘This paper studies a class of weighted composition operators and their spectrum on the Fock space. As an application, bounded self-adjoint, a class of complex symmetric weighted composition operators on the Fock space are characterized.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51522601 and 51421063)the Program for New Century Excellent Talents in University,China(Grant No.NCET-13-0173)
文摘Structural, electronic, and magnetic behaviors of 5d transition metal（TM） atom substituted divacancy（DV） graphene are investigated using first-principles calculations. Different 5d TM atoms（Hf, Ta, W, Re, Os, Ir, and Pt） are embedded in graphene, these impurity atoms replace 2 carbon atoms in the graphene sheet. It is revealed that the charge transfer occurs from 5d TM atoms to the graphene layer. Hf, Ta, and W substituted graphene structures exhibit a finite band gap at high symmetric K-point in their spin up and spin down channels with 0.783 μB, 1.65 μB, and 1.78 μB magnetic moments,respectively. Ir and Pt substituted graphene structures display indirect band gap semiconductor behavior. Interestingly, Os substituted graphene shows direct band gap semiconductor behavior having a band gap of approximately 0.4 e V in their spin up channel with 1.5 μB magnetic moment. Through density of states（DOS） analysis, we can predict that d orbitals of 5d TM atoms could be responsible for introducing ferromagnetism in the graphene layer. We believe that our obtained results provide a new route for potential applications of dilute magnetic semiconductors and half-metals in spintronic devices by employing 5d transition metal atom-doped graphene complexes.
基金Acknowledgments. The work was supported by State Key Laboratory of Scientific/Engineer- ing Computing, Chinese Academy of Sciences The International Science and Technology Co- operation Program of China under Grant 2010DFA14700 The Natural Science Foundation of China （NSFC） under Grant 11071192, P.R. China.
文摘The Modified Hermitian and skew-Hermitian splitting （MHSS） iteration method was presented and studied by Bai, Benzi and Chen （Computing, 87（2010）, 93-111） for solving a class of complex symmetric linear systems. In this paper, using the properties of Toeplitz matrix, we propose a class of structured MHSS iteration methods for solving the complex Toeplitz linear system. Theoretical analysis shows that the structured MHSS iteration method is unconditionally convergent to the exact solution. When the MHSS iteration method is used directly to complex symmetric Toeplitz linear systems, the computational costs can be considerately reduced by use of Toeplitz structure. Finally, numerical ex- periments show that the structured MHSS iteration method and the structured MHSS preconditioner are efficient for solving the complex Toeplitz linear system.
基金supported by the National Natural Science Foundation of China (Grant No.12171195).
文摘An operator T on a separable,infinite dimensional,complex Hilbert space H is called conjugate normal if C|T|C=|T^(*)| for some conjugate linear,isometric involution C on H.This paper focuses on the invariance of conjugate normality under similarity.Given an operator T,we prove that every operator A similar to T is conjugate normal if and only if there exist complex numbersλ_(1),λ_(2)such that(T-λ_(1))(T-λ_(2))=0.
