Currently,Mg-Gd-Y-Zn-Zr alloys face the issue of a long aging duration.To establish a short-time aging treatment route,the precipitation characteristics and their effects on mechanical properties during elevated-tempe...Currently,Mg-Gd-Y-Zn-Zr alloys face the issue of a long aging duration.To establish a short-time aging treatment route,the precipitation characteristics and their effects on mechanical properties during elevated-temperature heat treatment prior to low-temperature aging treatment,low-temperature single-stage aging treatment,and low-temperature two-stage aging treatment were studied.The following results were obtained:Wider intragranular lamellar phases,including 14-LPSO andγphases,are more easily obtained during long-term holding at heat treatment temperatures of 400℃and 450℃.Although these lamellar phases do not contribute to strengthening,they enhance ductility by hindering crack propagation.Micro-sizedβphases precipitate more readily at heat treatment temperatures of 300℃and 350℃.Intragranular needle-likeβphases are not effective strengthening phases,andβphase precipitating along grain boundaries form a networked distribution,which reduces ductility.The nano-sizedβ’phase,as the main strengthening phase,is more likely to precipitate during single-stage aging at temperatures of 200℃and 250℃.Theβ’phase formed at 200℃is denser,leading to higher strength,but requiring a longer aging time.For two-stage aging,which involves a primary-stage at 200℃for 8 to 12 h followed by a second-stage at 250℃for 10 h,the aging time is reduced to at least one-quarter of that required for single-stage aging at 200℃,ensuring strength while improving ductility.The formation of very dense nano-sizedβ’phases during the primary-stage aging facilitates the densification ofβ’phases during the subsequent second-stage aging.Additionally,the shortened aging time hinders the precipitation ofβphase along the grain boundaries,thus improving ductility.展开更多
This paper presents a more accurate battery state of charge(SOC)and state of health(SOH)estimation method.A lithium battery is represented by a nonlinear two-order resistance-capacitance equivalent circuit model.The m...This paper presents a more accurate battery state of charge(SOC)and state of health(SOH)estimation method.A lithium battery is represented by a nonlinear two-order resistance-capacitance equivalent circuit model.The model parameters are estimated by searching least square error optimization algorithm.Precisely defined by this method,the model parameters allow to accurately determine the capacity of the battery,which in turn allows to specify the SOC prediction value used as a basis for the SOH value.Application of the extended Kalman filter(EKF)removes the need of prior known initial SOC,and applying the fuzzy logic helps to eliminate the measurement and process noise.Simulation results obtained during the urban dynamometer driving schedule(UDDS)test show that the maximum error in estimation of the battery SOC is 0.66%.Battery capacity is estimate by offline updated Kalman filter,and then SOH will be predicted.The maximum error in estimation of the battery capacity is 1.55%.展开更多
Background A strong electromagnetic force is the major cause of vibration in dipole power supply cables.Moreover,the long-term operation of cables under vibration conditions leads to structural fatigue failure.Purpose...Background A strong electromagnetic force is the major cause of vibration in dipole power supply cables.Moreover,the long-term operation of cables under vibration conditions leads to structural fatigue failure.Purpose and methods To investigate the cable-laying scheme of a dipole power supply,a finite element model for the electromagnetic–structural coupling between cables and cleats was established.The electrodynamic forces were simulated for fixed-length cables in the horizontal,vertical,and bent models under pulse-current excitation.Subsequently,based on the optimized arrangement mode,the deformation of the cables and the stresses of the cleats were obtained.Results A small cable electrodynamic force was observed in the positive–negative interlace arrangement,and the cable deformation was caused by electrodynamic forces.The maximum cleat deformation occurred at the position with the largest electrodynamic force,where the cleats were reinforced.Moreover,the mechanical characteristics of the cables and cleats under pulse-current excitation are described intuitively and quantitatively,providing theoretical support for the cable-laying scheme of the dipole power supply.展开更多
基金supported by the special fund for Science and Technology Innovation Team of Shanxi Province,Central Guiding Local Science and Technology Development Fund Projects(No.YDZJSX20231A029)National Natural Science Foundation of China(No.52205428)Fundamental Research Program of Shanxi Province(No.20210302124206).
文摘Currently,Mg-Gd-Y-Zn-Zr alloys face the issue of a long aging duration.To establish a short-time aging treatment route,the precipitation characteristics and their effects on mechanical properties during elevated-temperature heat treatment prior to low-temperature aging treatment,low-temperature single-stage aging treatment,and low-temperature two-stage aging treatment were studied.The following results were obtained:Wider intragranular lamellar phases,including 14-LPSO andγphases,are more easily obtained during long-term holding at heat treatment temperatures of 400℃and 450℃.Although these lamellar phases do not contribute to strengthening,they enhance ductility by hindering crack propagation.Micro-sizedβphases precipitate more readily at heat treatment temperatures of 300℃and 350℃.Intragranular needle-likeβphases are not effective strengthening phases,andβphase precipitating along grain boundaries form a networked distribution,which reduces ductility.The nano-sizedβ’phase,as the main strengthening phase,is more likely to precipitate during single-stage aging at temperatures of 200℃and 250℃.Theβ’phase formed at 200℃is denser,leading to higher strength,but requiring a longer aging time.For two-stage aging,which involves a primary-stage at 200℃for 8 to 12 h followed by a second-stage at 250℃for 10 h,the aging time is reduced to at least one-quarter of that required for single-stage aging at 200℃,ensuring strength while improving ductility.The formation of very dense nano-sizedβ’phases during the primary-stage aging facilitates the densification ofβ’phases during the subsequent second-stage aging.Additionally,the shortened aging time hinders the precipitation ofβphase along the grain boundaries,thus improving ductility.
基金Open Fund Project of State Key Laboratory of Large Electric Transmission Systems and Equipment Technology(No.SKLLDJ042017005)。
文摘This paper presents a more accurate battery state of charge(SOC)and state of health(SOH)estimation method.A lithium battery is represented by a nonlinear two-order resistance-capacitance equivalent circuit model.The model parameters are estimated by searching least square error optimization algorithm.Precisely defined by this method,the model parameters allow to accurately determine the capacity of the battery,which in turn allows to specify the SOC prediction value used as a basis for the SOH value.Application of the extended Kalman filter(EKF)removes the need of prior known initial SOC,and applying the fuzzy logic helps to eliminate the measurement and process noise.Simulation results obtained during the urban dynamometer driving schedule(UDDS)test show that the maximum error in estimation of the battery SOC is 0.66%.Battery capacity is estimate by offline updated Kalman filter,and then SOH will be predicted.The maximum error in estimation of the battery capacity is 1.55%.
文摘Background A strong electromagnetic force is the major cause of vibration in dipole power supply cables.Moreover,the long-term operation of cables under vibration conditions leads to structural fatigue failure.Purpose and methods To investigate the cable-laying scheme of a dipole power supply,a finite element model for the electromagnetic–structural coupling between cables and cleats was established.The electrodynamic forces were simulated for fixed-length cables in the horizontal,vertical,and bent models under pulse-current excitation.Subsequently,based on the optimized arrangement mode,the deformation of the cables and the stresses of the cleats were obtained.Results A small cable electrodynamic force was observed in the positive–negative interlace arrangement,and the cable deformation was caused by electrodynamic forces.The maximum cleat deformation occurred at the position with the largest electrodynamic force,where the cleats were reinforced.Moreover,the mechanical characteristics of the cables and cleats under pulse-current excitation are described intuitively and quantitatively,providing theoretical support for the cable-laying scheme of the dipole power supply.
