While modeling a power supply system for an electric railway traction, knowing equivalent circuits of locomotives supplied this way is an essential issue. In alternating current traction, it is important to diagnose i...While modeling a power supply system for an electric railway traction, knowing equivalent circuits of locomotives supplied this way is an essential issue. In alternating current traction, it is important to diagnose inter alia processes taking place in transformers installed on electric vehicles. This article presents specific phenomena occurring during the work of mono-phase, multi-winding, multisystem （systems AC： 50 Hz, 16.7 Hz） laboratory traction transformer. It also shows difficulties encountered during the process of identifying multi-port equivalent scheme＇s elements of the described device, in which a construction defect occurs.展开更多
It is pointed out that to numerically estimate the effective properties and local fields of matrix-inclusion composites,a commonly adopted method is accompanied with some serious draw- backs.We call this method the no...It is pointed out that to numerically estimate the effective properties and local fields of matrix-inclusion composites,a commonly adopted method is accompanied with some serious draw- backs.We call this method the nominal loading scheme(NLS),which considers the actual inclusion distribution inside a finite domain,Ω say,treats the external domain of Ω to be of the pure matrix ma- terial,and imposes the actural traction,σ~∞ say on the remote boundary.It thus gives rise to the fol- lowing basic problems:(i)Can NLS be improved remarkably just by adjusting σ~∞?(it)What is the relationship between the size of Ω and the,scale of inclusions?(iii)Which choice is better in calculating the effective properties,the whole domain Ω or an appropriately selected sub-domain of Ω? Targeting these problems,the equivalent loading,scheme (ELS)and equivalent matrix scheme(EMS)are proposed.It is theoretically analyzed that both ELS and EMS can be used to precisely simulating the effective properties and local fields of matrix-inclusion composites,and both ELS and EMS are self-approved. As an application,ELS combined with a m-called pseudo-dislocations method is used to evaluate the effective properties and local fields of two-dimensional two-phase compos- ites with close-packed circular inclusions,or randomly distributed circular inclusions, or randomly distributed mierocracks.The results show that substituting the remote trac- tion σ~∞ with the effective stress field σ~E suggested by IDD scheme is a simple and effec- tive method,and the estimation of the effective properties and local fields is very close to the accurate,solution.展开更多
文摘While modeling a power supply system for an electric railway traction, knowing equivalent circuits of locomotives supplied this way is an essential issue. In alternating current traction, it is important to diagnose inter alia processes taking place in transformers installed on electric vehicles. This article presents specific phenomena occurring during the work of mono-phase, multi-winding, multisystem （systems AC： 50 Hz, 16.7 Hz） laboratory traction transformer. It also shows difficulties encountered during the process of identifying multi-port equivalent scheme＇s elements of the described device, in which a construction defect occurs.
基金the National Natural Science Foundation of China(No.19525207)
文摘It is pointed out that to numerically estimate the effective properties and local fields of matrix-inclusion composites,a commonly adopted method is accompanied with some serious draw- backs.We call this method the nominal loading scheme(NLS),which considers the actual inclusion distribution inside a finite domain,Ω say,treats the external domain of Ω to be of the pure matrix ma- terial,and imposes the actural traction,σ~∞ say on the remote boundary.It thus gives rise to the fol- lowing basic problems:(i)Can NLS be improved remarkably just by adjusting σ~∞?(it)What is the relationship between the size of Ω and the,scale of inclusions?(iii)Which choice is better in calculating the effective properties,the whole domain Ω or an appropriately selected sub-domain of Ω? Targeting these problems,the equivalent loading,scheme (ELS)and equivalent matrix scheme(EMS)are proposed.It is theoretically analyzed that both ELS and EMS can be used to precisely simulating the effective properties and local fields of matrix-inclusion composites,and both ELS and EMS are self-approved. As an application,ELS combined with a m-called pseudo-dislocations method is used to evaluate the effective properties and local fields of two-dimensional two-phase compos- ites with close-packed circular inclusions,or randomly distributed circular inclusions, or randomly distributed mierocracks.The results show that substituting the remote trac- tion σ~∞ with the effective stress field σ~E suggested by IDD scheme is a simple and effec- tive method,and the estimation of the effective properties and local fields is very close to the accurate,solution.
