In this note, we provide an effective proof of the fundamental structure theorem of finitely generated modules over a principal ideal domain, from which we find the minimality of decomposition for a finitely generated...In this note, we provide an effective proof of the fundamental structure theorem of finitely generated modules over a principal ideal domain, from which we find the minimality of decomposition for a finitely generated module over a principal ideal domain.展开更多
Let Fbe a locally defined formation consisting of locally soluble groups, G a hyper-(cyclic or finite) locally soluble group and A a noetherian ZG-module with all irreducible ZG-factors being finite, G∈F, f(∞)f(p), ...Let Fbe a locally defined formation consisting of locally soluble groups, G a hyper-(cyclic or finite) locally soluble group and A a noetherian ZG-module with all irreducible ZG-factors being finite, G∈F, f(∞)f(p), f(p)≠ for each p∈π. The following conclutions are obtained: (1) if there exists a maximal submodule B of A such that A/B is F-central in G and B has no nonzero F-central ZG-factors, then A has an F-decomposition; (2) if there exists an irreducible F-central submodule B of A such that all ZG-composition factors of A/B are F-ecentric, then A has an F-decomposition.展开更多
Let (?) be a formation locally defined by f(P), G ∈ (?) and A a ZG-module, where p ∈ π = { all primes and symbol ∞}. Then a p-main-factor U/V of G is said to be (?)-central in G if G/CG(U/V) ∈f(p). In this paper,...Let (?) be a formation locally defined by f(P), G ∈ (?) and A a ZG-module, where p ∈ π = { all primes and symbol ∞}. Then a p-main-factor U/V of G is said to be (?)-central in G if G/CG(U/V) ∈f(p). In this paper, we have proved that: let (?) be a locally defined formation consisting of locally soluble groups, G a hyper-(cyclic or finite) locally soluble group and A an artinian ZG-module with all irreducible ZG-factors of A being finite; if G ∈ (?), f(∞) ≡ f(p) . f(p)≠φ for each p ∈ π, A has an (?)-decomposition.展开更多
With the aid of commercial finite element analysis software package ANSYS,investigations are made on the contributions of main components to stiffness of the main module for parallel machine tools,and it is found that...With the aid of commercial finite element analysis software package ANSYS,investigations are made on the contributions of main components to stiffness of the main module for parallel machine tools,and it is found that the frame is the main contributor.Then,influences of constraints,strut length and working ways of the main module have also been investigated.It can be concluded that when one of the main planes of the frame without linear drive unit is constrained,the largest whole stiffness can be acquired.And,the stiffness is much better when the main module is used in a vertical machine tool instead of a horizontal one.Finally,the principle of stiffness variation is summarized when the mobile platform reaches various positions within its working space and when various loads are applied.These achievements have provided critical instructions for the design of the main module for parallel machine tools.展开更多
In this paper, we prove that the Toeplitz operator with finite Blaschke product symbol Sψ（z） on Nφ has at least m non-trivial minimal reducing subspaces, where m is the dimension of H^2（Гω）⊙φ（ω）H^2（Гω...In this paper, we prove that the Toeplitz operator with finite Blaschke product symbol Sψ（z） on Nφ has at least m non-trivial minimal reducing subspaces, where m is the dimension of H^2（Гω）⊙φ（ω）H^2（Гω）. Moreover, the restriction of Sψ（z） on any of these minimal reducing subspaces is unitary equivalent to the Bergman shift Mz.展开更多
For a ring A, an extension ring B, a fixed right A-module M, the endomorphism ring D formed by M, the endomorphism ring E formed by , and the endomorphism ring F formed by HomA (B,M), we present equivalences and duali...For a ring A, an extension ring B, a fixed right A-module M, the endomorphism ring D formed by M, the endomorphism ring E formed by , and the endomorphism ring F formed by HomA (B,M), we present equivalences and dualities between subcategories of B-modules which are finitely cogenerated injective as A-modules and E-modules and F-modules which are finitely generated projective as D-modules.展开更多
Let G be a hyper finite locally solvable group, A a minimax ZG-medule, a locally defined formation consisting of locally solvable groups, A has no nonzero infinite irreducible ZG-factors, and G ∈ . The following resu...Let G be a hyper finite locally solvable group, A a minimax ZG-medule, a locally defined formation consisting of locally solvable groups, A has no nonzero infinite irreducible ZG-factors, and G ∈ . The following results are proved： if A has a maximal submodule B such that A/B is , central in G and B has no nonzero central ZG-factors, then A has an decomposition; ifA has an irreducible central submodule B such that all ZG-composition factors of A/B are o^eccentric, then A has an decomposition.展开更多
To reduce thrust ripple and cost and improve the average thrust of permanent magnet linear motors,a modular dual-field modulation permanent magnet linear motor was studied,and the parameters were optimized.First,sensi...To reduce thrust ripple and cost and improve the average thrust of permanent magnet linear motors,a modular dual-field modulation permanent magnet linear motor was studied,and the parameters were optimized.First,sensitive parameters were selected using the Taguchi method,and then the optimal variables were sampled using the optimal Latin hypercube experimental design method and an ensemble of surrogates model of optimization objectives,and its accuracy was verified.Next,a multi-objective particle swarm optimization algorithm was used to optimize the purpose of“maximum average thrust and minimum thrust ripple”,and the Pareto front of average thrust and thrust ripple was obtained.Finite element analysis showed that the optimized modular dual flux-modulation permanent magnet linear motor(MDFMPMLM)had a 29.5%reduction in thrust ripple and a 5%increase in average thrust compared to the original motor.This study provided an effective method for improving the performance of permanent magnet linear motors.展开更多
为研究浮式生产储卸油装置(floating production storage and offloading,FPSO)浮筒关键节点的疲劳强度问题,本文基于FPSO三舱段、浮筒锥体、浮筒转塔、锥形对接模块(mating cone module,MCM)的整体模型,通过应力分析确定出应力较为集...为研究浮式生产储卸油装置(floating production storage and offloading,FPSO)浮筒关键节点的疲劳强度问题,本文基于FPSO三舱段、浮筒锥体、浮筒转塔、锥形对接模块(mating cone module,MCM)的整体模型,通过应力分析确定出应力较为集中的区域并作为热点,建立精细化网格的子模型以获得热点应力。基于力传递函数的方法,根据规范开展浮筒和MCM的疲劳简化分析,研究系泊和立管载荷对浮筒局部结构的疲劳影响。结果表明,浮筒锥体、浮筒转塔和MCM中关键节点的疲劳强度均满足设计疲劳强度要求,其中最薄弱的热点结构HS1的疲劳寿命为3262 a,大于20 a的设计寿命,满足FPSO单点系泊浮筒的设计预期要求。展开更多
文摘In this note, we provide an effective proof of the fundamental structure theorem of finitely generated modules over a principal ideal domain, from which we find the minimality of decomposition for a finitely generated module over a principal ideal domain.
基金TheNationalNaturalScienceFoundationofChina (No .10 1710 74 )
文摘Let Fbe a locally defined formation consisting of locally soluble groups, G a hyper-(cyclic or finite) locally soluble group and A a noetherian ZG-module with all irreducible ZG-factors being finite, G∈F, f(∞)f(p), f(p)≠ for each p∈π. The following conclutions are obtained: (1) if there exists a maximal submodule B of A such that A/B is F-central in G and B has no nonzero F-central ZG-factors, then A has an F-decomposition; (2) if there exists an irreducible F-central submodule B of A such that all ZG-composition factors of A/B are F-ecentric, then A has an F-decomposition.
文摘Let (?) be a formation locally defined by f(P), G ∈ (?) and A a ZG-module, where p ∈ π = { all primes and symbol ∞}. Then a p-main-factor U/V of G is said to be (?)-central in G if G/CG(U/V) ∈f(p). In this paper, we have proved that: let (?) be a locally defined formation consisting of locally soluble groups, G a hyper-(cyclic or finite) locally soluble group and A an artinian ZG-module with all irreducible ZG-factors of A being finite; if G ∈ (?), f(∞) ≡ f(p) . f(p)≠φ for each p ∈ π, A has an (?)-decomposition.
文摘With the aid of commercial finite element analysis software package ANSYS,investigations are made on the contributions of main components to stiffness of the main module for parallel machine tools,and it is found that the frame is the main contributor.Then,influences of constraints,strut length and working ways of the main module have also been investigated.It can be concluded that when one of the main planes of the frame without linear drive unit is constrained,the largest whole stiffness can be acquired.And,the stiffness is much better when the main module is used in a vertical machine tool instead of a horizontal one.Finally,the principle of stiffness variation is summarized when the mobile platform reaches various positions within its working space and when various loads are applied.These achievements have provided critical instructions for the design of the main module for parallel machine tools.
文摘In this paper, we prove that the Toeplitz operator with finite Blaschke product symbol Sψ（z） on Nφ has at least m non-trivial minimal reducing subspaces, where m is the dimension of H^2（Гω）⊙φ（ω）H^2（Гω）. Moreover, the restriction of Sψ（z） on any of these minimal reducing subspaces is unitary equivalent to the Bergman shift Mz.
文摘For a ring A, an extension ring B, a fixed right A-module M, the endomorphism ring D formed by M, the endomorphism ring E formed by , and the endomorphism ring F formed by HomA (B,M), we present equivalences and dualities between subcategories of B-modules which are finitely cogenerated injective as A-modules and E-modules and F-modules which are finitely generated projective as D-modules.
文摘Let G be a hyper finite locally solvable group, A a minimax ZG-medule, a locally defined formation consisting of locally solvable groups, A has no nonzero infinite irreducible ZG-factors, and G ∈ . The following results are proved： if A has a maximal submodule B such that A/B is , central in G and B has no nonzero central ZG-factors, then A has an decomposition; ifA has an irreducible central submodule B such that all ZG-composition factors of A/B are o^eccentric, then A has an decomposition.
文摘To reduce thrust ripple and cost and improve the average thrust of permanent magnet linear motors,a modular dual-field modulation permanent magnet linear motor was studied,and the parameters were optimized.First,sensitive parameters were selected using the Taguchi method,and then the optimal variables were sampled using the optimal Latin hypercube experimental design method and an ensemble of surrogates model of optimization objectives,and its accuracy was verified.Next,a multi-objective particle swarm optimization algorithm was used to optimize the purpose of“maximum average thrust and minimum thrust ripple”,and the Pareto front of average thrust and thrust ripple was obtained.Finite element analysis showed that the optimized modular dual flux-modulation permanent magnet linear motor(MDFMPMLM)had a 29.5%reduction in thrust ripple and a 5%increase in average thrust compared to the original motor.This study provided an effective method for improving the performance of permanent magnet linear motors.
文摘为研究浮式生产储卸油装置(floating production storage and offloading,FPSO)浮筒关键节点的疲劳强度问题,本文基于FPSO三舱段、浮筒锥体、浮筒转塔、锥形对接模块(mating cone module,MCM)的整体模型,通过应力分析确定出应力较为集中的区域并作为热点,建立精细化网格的子模型以获得热点应力。基于力传递函数的方法,根据规范开展浮筒和MCM的疲劳简化分析,研究系泊和立管载荷对浮筒局部结构的疲劳影响。结果表明,浮筒锥体、浮筒转塔和MCM中关键节点的疲劳强度均满足设计疲劳强度要求,其中最薄弱的热点结构HS1的疲劳寿命为3262 a,大于20 a的设计寿命,满足FPSO单点系泊浮筒的设计预期要求。
