According to running experience of high speed railway abroad, a full attention must be paid to some requirements of specification of rails for high speed railway, such as material mechanical properties, dimension tole...According to running experience of high speed railway abroad, a full attention must be paid to some requirements of specification of rails for high speed railway, such as material mechanical properties, dimension tolerances, straightness, surface flatness and so on. It is suggested that the long length rails should be laid in high speed railway, and the feasibility of producing, welding and transporting of long length rails should be researched. On the basis of technical innovation of domestic manufacturers, it is practicable to lay 50-100 m long\|length homemade rails in high speed railway of China. The following welding programme of rails for high speed railway can be adop\| ted: 50-100 m long length rails can be welded as 500 m long rail string through flash butt welding in plant, then in field the rail string can be welded through a mobile flash butt welding or thermit welding. As the specification of rails for high speed railway is rigorous, some related techniques to long length rails should be researched and practised as soon as possible, including mobile flash butt welding technique, transporting and reinforcing techniques of long length rails, etc..展开更多
According to the experimental results of model beams, the curvature of a partially prestressed concrete beam is defined, then the influence of PPR(partial prestressing ratio), net reinforcement index, concrete streng...According to the experimental results of model beams, the curvature of a partially prestressed concrete beam is defined, then the influence of PPR(partial prestressing ratio), net reinforcement index, concrete strength and fatigue on ductility of partially prestressed concrete beam are discussed respectively.展开更多
In this paper we consider domain decomposition methods for three-dimensional elliptic problems with Lagrange multipliers, and construct a kind of simple preconditioner for the corresponding interface equation. It will...In this paper we consider domain decomposition methods for three-dimensional elliptic problems with Lagrange multipliers, and construct a kind of simple preconditioner for the corresponding interface equation. It will be shown that condition number of the resulting preconditioned interface matrix is almost optimal.展开更多
文摘According to running experience of high speed railway abroad, a full attention must be paid to some requirements of specification of rails for high speed railway, such as material mechanical properties, dimension tolerances, straightness, surface flatness and so on. It is suggested that the long length rails should be laid in high speed railway, and the feasibility of producing, welding and transporting of long length rails should be researched. On the basis of technical innovation of domestic manufacturers, it is practicable to lay 50-100 m long\|length homemade rails in high speed railway of China. The following welding programme of rails for high speed railway can be adop\| ted: 50-100 m long length rails can be welded as 500 m long rail string through flash butt welding in plant, then in field the rail string can be welded through a mobile flash butt welding or thermit welding. As the specification of rails for high speed railway is rigorous, some related techniques to long length rails should be researched and practised as soon as possible, including mobile flash butt welding technique, transporting and reinforcing techniques of long length rails, etc..
文摘According to the experimental results of model beams, the curvature of a partially prestressed concrete beam is defined, then the influence of PPR(partial prestressing ratio), net reinforcement index, concrete strength and fatigue on ductility of partially prestressed concrete beam are discussed respectively.
基金This research is supported by the Special Funds for Major State Research Projects of China(G 1999032804)
文摘In this paper we consider domain decomposition methods for three-dimensional elliptic problems with Lagrange multipliers, and construct a kind of simple preconditioner for the corresponding interface equation. It will be shown that condition number of the resulting preconditioned interface matrix is almost optimal.
