Hunting stability is an important performance criterion in railway vehicles.This study proposes an incorporation of a bio-inspired limb-like structure(LLS)-based nonlinear damping into the motor suspension system for ...Hunting stability is an important performance criterion in railway vehicles.This study proposes an incorporation of a bio-inspired limb-like structure(LLS)-based nonlinear damping into the motor suspension system for traction units to improve the nonlinear critical speed and hunting stability of high-speed trains(HSTs).Initially,a vibration transmission analysis is conducted on a HST vehicle and a metro vehicle that suffered from hunting motion to explore the effect of different motor suspension systems from on-track tests.Subsequently,a simplified lateral dynamics model of an HST bogie is established to investigate the influence of the motor suspension on the bogie hunting behavior.The bifurcation analysis is applied to optimize the motor suspension parameters for high critical speed.Then,the nonlinear damping of the bio-inspired LLS,which has a positive correlation with the relative displacement,can further improve the modal damping of hunting motion and nonlinear critical speed compared with the linear motor suspension system.Furthermore,a comprehensive numerical model of a high-speed train,considering all nonlinearities,is established to investigate the influence of different types of motor suspension.The simulation results are well consistent with the theoretical analysis.The benefits of employing nonlinear damping of the bio-inspired LLS into the motor suspension of HSTs to enhance bogie hunting stability are thoroughly validated.展开更多
Objective To investigate the effect of H2S on lower limb ischemia-reperfusion （LIR） induced lung injury and explore the underlying mechanism. Methods Wistar rats were randomly divided into control group, IR group, I...Objective To investigate the effect of H2S on lower limb ischemia-reperfusion （LIR） induced lung injury and explore the underlying mechanism. Methods Wistar rats were randomly divided into control group, IR group, IR＋ Sodium Hydrosulphide （NariS） group and IR＋ DL-propargylglycine （PPG） group. IR group as lung injury model induced by LIR were given 4 h reperfusion following 4 h ischemia of bilateral hindlimbs with rubber bands. NariS （0.78 mg/kg） as exogenous H2S donor and PPG （60 mg/kg） which can suppress endogenous H2S production were administrated before LIR, respectively. The lungs were removed for histologic analysis, the determination of wet-to-dry weight ratios and the measurement of mRNA and protein levels of aquaporin-1 （AQP1）, aquaporin-5 （AQP5） as indexes of water transport abnormality, and mRNA and protein levels of Toll-like receptor 4 （TLR4）, myeloid differentiation primary-response gene 88 （MyD88） and p-NF-KB as indexes of inflammation. Results LIR induced lung injury was accompanied with upregulation of TLR4-Myd88-NF-κB pathway and downregulation of AQP1/AQP5. NariS pre-treatment reduced lung injury with increasing AQP1/AQP5 expression and inhibition of TLR4-Myd88-NF-KB pathway, but PPG adjusted AO.PJAO.Ps and TLR4 pathway to the opposite side and exacerbated lung injury. Conclusion Endogenous H2S, TLR4-Myd88-NF-κB pathway and AQP1/AQP5 were involved in LIR induced lung injury. Increased H2S would alleviate lung injury and the effect is at least partially depend on the adjustment of TLR4-Myd88-NF-κB pathway and AQP1/AQP5 expression to reduce inflammatory reaction and lessen pulmonary edema.展开更多
基金the National Natural Science Foundation of China (Nos. 52388102, 52072317 and U2268210)the State Key Laboratory of Rail Transit Vehicle System (No. 2024RVL-T12)
文摘Hunting stability is an important performance criterion in railway vehicles.This study proposes an incorporation of a bio-inspired limb-like structure(LLS)-based nonlinear damping into the motor suspension system for traction units to improve the nonlinear critical speed and hunting stability of high-speed trains(HSTs).Initially,a vibration transmission analysis is conducted on a HST vehicle and a metro vehicle that suffered from hunting motion to explore the effect of different motor suspension systems from on-track tests.Subsequently,a simplified lateral dynamics model of an HST bogie is established to investigate the influence of the motor suspension on the bogie hunting behavior.The bifurcation analysis is applied to optimize the motor suspension parameters for high critical speed.Then,the nonlinear damping of the bio-inspired LLS,which has a positive correlation with the relative displacement,can further improve the modal damping of hunting motion and nonlinear critical speed compared with the linear motor suspension system.Furthermore,a comprehensive numerical model of a high-speed train,considering all nonlinearities,is established to investigate the influence of different types of motor suspension.The simulation results are well consistent with the theoretical analysis.The benefits of employing nonlinear damping of the bio-inspired LLS into the motor suspension of HSTs to enhance bogie hunting stability are thoroughly validated.
基金supported by the Military Health Care Foundation during the 12th Five-year Plan Period(11BZ21)the Military Scientific Research Foundation during the 12th Five-year Plan Period(BWS12J051)
文摘Objective To investigate the effect of H2S on lower limb ischemia-reperfusion （LIR） induced lung injury and explore the underlying mechanism. Methods Wistar rats were randomly divided into control group, IR group, IR＋ Sodium Hydrosulphide （NariS） group and IR＋ DL-propargylglycine （PPG） group. IR group as lung injury model induced by LIR were given 4 h reperfusion following 4 h ischemia of bilateral hindlimbs with rubber bands. NariS （0.78 mg/kg） as exogenous H2S donor and PPG （60 mg/kg） which can suppress endogenous H2S production were administrated before LIR, respectively. The lungs were removed for histologic analysis, the determination of wet-to-dry weight ratios and the measurement of mRNA and protein levels of aquaporin-1 （AQP1）, aquaporin-5 （AQP5） as indexes of water transport abnormality, and mRNA and protein levels of Toll-like receptor 4 （TLR4）, myeloid differentiation primary-response gene 88 （MyD88） and p-NF-KB as indexes of inflammation. Results LIR induced lung injury was accompanied with upregulation of TLR4-Myd88-NF-κB pathway and downregulation of AQP1/AQP5. NariS pre-treatment reduced lung injury with increasing AQP1/AQP5 expression and inhibition of TLR4-Myd88-NF-KB pathway, but PPG adjusted AO.PJAO.Ps and TLR4 pathway to the opposite side and exacerbated lung injury. Conclusion Endogenous H2S, TLR4-Myd88-NF-κB pathway and AQP1/AQP5 were involved in LIR induced lung injury. Increased H2S would alleviate lung injury and the effect is at least partially depend on the adjustment of TLR4-Myd88-NF-κB pathway and AQP1/AQP5 expression to reduce inflammatory reaction and lessen pulmonary edema.
