The 20,000-ton combined train running has greatly promoted China’s heavy-haul railway transportation capability. The application of controllable train-tail devices could improve the braking wave of the train and brak...The 20,000-ton combined train running has greatly promoted China’s heavy-haul railway transportation capability. The application of controllable train-tail devices could improve the braking wave of the train and braking synchronism, and alleviate longitudinal impulse.However, the characteristics of the controllable train-tail device such as exhaust area, exhaust duration and exhaust action time are not uniform in practice, and their effects on the longitudinal impulse of the train are not apparent,which is worth studying. In this work, according to the formation of the Datong-Qinhuangdao Railway, the train air brake and longitudinal dynamics simulation system(TABLDSS) is applied to establish a 20,000-ton combined train model with the controllable train-tail device, and the braking characteristics and the longitudinal impulse of the train are calculated synchronously with changing the air exhaust time, exhaust area, and action lag time under initial braking. The results show that the maximum coupler force of the combined train will decrease with the extension of the continuous exhaust time, while the total exhaust time of the controllable train-tail device remains unchanged;the maximum coupler force of the combined train reduces by32.5% with the exhaust area increasing from 70% to 140%;when the lag time between the controllable train-tail device and the master locomotive is more than 1.5 s, the maximum coupler force of the train increases along with the time difference enlargement.展开更多
Bogies are responsible for a significant amount of aerodynamic resistance and noise,both of which negatively affect high-speed train performance and passenger comfort.In the present study,the passive control method is...Bogies are responsible for a significant amount of aerodynamic resistance and noise,both of which negatively affect high-speed train performance and passenger comfort.In the present study,the passive control method is applied in designing the bogie cabins of a high-speed train to improve its aerodynamic characteristics.Two passive control measures are introduced,namely,adding a spoiler and creating diversion grooves near the bogie cabins.Furthermore,the aerodynamic and aeroacoustic characteristics of a high-speed train operating at 350 km/h under different control strategies are numerically investigated using the improved-delayed-detached-eddy simulation(IDDES)and the acoustic finite element method(FEM).The impacts of passive control devices on drag reduction,slipstream,and aerodynamic noise are presented and discussed.Numerical results reveal that the passive control devices have a major effect on the slipstream around the train.The amplitude of the fluctuating pressure is higher in the first half of the train than in the second half.The first bogie has the maximum amplitude of the acoustic pressure for both the train with and without passive devices.In the far field,the spoiler installation and placement of the diversion grooves in the front of the bogie cabin can significantly reduce aerodynamic drag and noise.Hence,as shown in this study,using passive control methods to improve the aerodynamic and aeroacoustic properties of high-speed trains can be a viable option.展开更多
Urban rail trains have undergone rapid development in recent years due to their punctuality,high capacity and energy efficiency.Urban trains require frequent start/stop operations and are,therefore,prone to high energ...Urban rail trains have undergone rapid development in recent years due to their punctuality,high capacity and energy efficiency.Urban trains require frequent start/stop operations and are,therefore,prone to high energy losses.As trains have high inertia,the energy that can be recovered from braking comes in short bursts of high power.To effectively recover such braking energy,an onboard supercapacitor system based on a radial basis function neural networkbased sliding mode control system is proposed,which provides robust adaptive performance.The supercapacitor energy storage system is connected to a bidirectional DC/DC converter to provide traction energy or absorb regenerative braking energy.In the Boost and Buck modes,the state-space averaging method is used to establish a model and perform exact linearization.An adaptive sliding mode controller is designed,and simulation results show that it can effectively solve the problems of low energy utilization and large voltage fluctuations in urban rail electricity grids,and maximise the recovery and utilization of regenerative braking energy.展开更多
目的:拟探究新型踝关节平衡装置训练对功能性踝关节不稳(FAI)患者踝关节功能及姿势控制能力的影响。方法:将符合纳入条件的FAI患者45名随机分为常规组(n=21)和平衡组(n=24),2组患者分别接受常规功能训练和新型踝关节平衡训练装置训练,8...目的:拟探究新型踝关节平衡装置训练对功能性踝关节不稳(FAI)患者踝关节功能及姿势控制能力的影响。方法:将符合纳入条件的FAI患者45名随机分为常规组(n=21)和平衡组(n=24),2组患者分别接受常规功能训练和新型踝关节平衡训练装置训练,8周干预前后,使用Noraxon表面肌电测试系统和Trap-door踝关节内翻诱发装置进行踝周肌肉潜伏期的测试,使用Biodex Systems IV型等速肌力测试系统进行踝关节位置觉和踝内外翻等速肌力的测试,使用Y型平衡测试(YBT)系统进行姿势控制能力的测试,使用坎伯兰踝关节不稳定工具(CAIT)对FAI患者进行评分。结果:干预8周后,平衡组FAI患者的CAIT评分、踝周肌肉潜伏期(腓肠肌内侧头、腓肠肌外侧头、腓骨长肌、胫骨前肌)、峰值踝外翻力矩和姿势控制能力(内收、外展的最大距离)相比于干预前显著改善(P<0.05),且明显优于对照组(P<0.05)。结论:相比于常规功能训练,踝关节平衡装置训练可以更显著地提高FAI患者的姿势控制能力和踝关节的功能。展开更多
基金China National Railway Group Co.,Ltd(N2020J037).
文摘The 20,000-ton combined train running has greatly promoted China’s heavy-haul railway transportation capability. The application of controllable train-tail devices could improve the braking wave of the train and braking synchronism, and alleviate longitudinal impulse.However, the characteristics of the controllable train-tail device such as exhaust area, exhaust duration and exhaust action time are not uniform in practice, and their effects on the longitudinal impulse of the train are not apparent,which is worth studying. In this work, according to the formation of the Datong-Qinhuangdao Railway, the train air brake and longitudinal dynamics simulation system(TABLDSS) is applied to establish a 20,000-ton combined train model with the controllable train-tail device, and the braking characteristics and the longitudinal impulse of the train are calculated synchronously with changing the air exhaust time, exhaust area, and action lag time under initial braking. The results show that the maximum coupler force of the combined train will decrease with the extension of the continuous exhaust time, while the total exhaust time of the controllable train-tail device remains unchanged;the maximum coupler force of the combined train reduces by32.5% with the exhaust area increasing from 70% to 140%;when the lag time between the controllable train-tail device and the master locomotive is more than 1.5 s, the maximum coupler force of the train increases along with the time difference enlargement.
基金This work was supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No. 2019020)the Strategic Priority Research Program of the Chinese Academy of Sciences (Class B) (Grant No. XDB22020000)Informatization Plan of the Chinese Academy of Sciences (Grant No. XXH13506-204).
文摘Bogies are responsible for a significant amount of aerodynamic resistance and noise,both of which negatively affect high-speed train performance and passenger comfort.In the present study,the passive control method is applied in designing the bogie cabins of a high-speed train to improve its aerodynamic characteristics.Two passive control measures are introduced,namely,adding a spoiler and creating diversion grooves near the bogie cabins.Furthermore,the aerodynamic and aeroacoustic characteristics of a high-speed train operating at 350 km/h under different control strategies are numerically investigated using the improved-delayed-detached-eddy simulation(IDDES)and the acoustic finite element method(FEM).The impacts of passive control devices on drag reduction,slipstream,and aerodynamic noise are presented and discussed.Numerical results reveal that the passive control devices have a major effect on the slipstream around the train.The amplitude of the fluctuating pressure is higher in the first half of the train than in the second half.The first bogie has the maximum amplitude of the acoustic pressure for both the train with and without passive devices.In the far field,the spoiler installation and placement of the diversion grooves in the front of the bogie cabin can significantly reduce aerodynamic drag and noise.Hence,as shown in this study,using passive control methods to improve the aerodynamic and aeroacoustic properties of high-speed trains can be a viable option.
基金the Science and Technology Project of Henan Province under Grant No.14210221036.
文摘Urban rail trains have undergone rapid development in recent years due to their punctuality,high capacity and energy efficiency.Urban trains require frequent start/stop operations and are,therefore,prone to high energy losses.As trains have high inertia,the energy that can be recovered from braking comes in short bursts of high power.To effectively recover such braking energy,an onboard supercapacitor system based on a radial basis function neural networkbased sliding mode control system is proposed,which provides robust adaptive performance.The supercapacitor energy storage system is connected to a bidirectional DC/DC converter to provide traction energy or absorb regenerative braking energy.In the Boost and Buck modes,the state-space averaging method is used to establish a model and perform exact linearization.An adaptive sliding mode controller is designed,and simulation results show that it can effectively solve the problems of low energy utilization and large voltage fluctuations in urban rail electricity grids,and maximise the recovery and utilization of regenerative braking energy.
文摘目的:拟探究新型踝关节平衡装置训练对功能性踝关节不稳(FAI)患者踝关节功能及姿势控制能力的影响。方法:将符合纳入条件的FAI患者45名随机分为常规组(n=21)和平衡组(n=24),2组患者分别接受常规功能训练和新型踝关节平衡训练装置训练,8周干预前后,使用Noraxon表面肌电测试系统和Trap-door踝关节内翻诱发装置进行踝周肌肉潜伏期的测试,使用Biodex Systems IV型等速肌力测试系统进行踝关节位置觉和踝内外翻等速肌力的测试,使用Y型平衡测试(YBT)系统进行姿势控制能力的测试,使用坎伯兰踝关节不稳定工具(CAIT)对FAI患者进行评分。结果:干预8周后,平衡组FAI患者的CAIT评分、踝周肌肉潜伏期(腓肠肌内侧头、腓肠肌外侧头、腓骨长肌、胫骨前肌)、峰值踝外翻力矩和姿势控制能力(内收、外展的最大距离)相比于干预前显著改善(P<0.05),且明显优于对照组(P<0.05)。结论:相比于常规功能训练,踝关节平衡装置训练可以更显著地提高FAI患者的姿势控制能力和踝关节的功能。
