Swing nose crossings(SNXs)have been widely used in heavy haul railways to create a smoother load transfer and hence reduced impact load.However,the current design of SNXs hasn’t been fully examined under heavy haul o...Swing nose crossings(SNXs)have been widely used in heavy haul railways to create a smoother load transfer and hence reduced impact load.However,the current design of SNXs hasn’t been fully examined under heavy haul operating conditions.Additionally,maintenance guidelines for SNX wear-related issues in Australian heavy haul railways are relatively lacking.As such,this study aims to investigate the dynamic response of the wheel-rail contact and analyse the wear performance of an SNX currently used in Australian heavy haul railways.Dynamic implicit-explicit finite element analysis was conducted to simulate the wheel-rail contact along the SNX.The distribution of the wear intensity over the SNX was identified by using a local contact-based wear model.The influence of various scenarios on wear was also explored.The results verify the improved dynamic performance of the SNX,as the increased contact force after load transfer remains below 1.2 times the static load.The findings also indicate that the decrease in relative height and increase in nose rail inclination result in greater wear on the nose rail.Notably,the SNX considered in the current study exhibits better wear performance when used with moderately worn wheels.展开更多
In this study,a novel synergistic swing energy-regenerative hybrid system(SSEHS)for excavators with a large inertia slewing platform is constructed.With the SSEHS,the pressure boosting and output energy synergy of mul...In this study,a novel synergistic swing energy-regenerative hybrid system(SSEHS)for excavators with a large inertia slewing platform is constructed.With the SSEHS,the pressure boosting and output energy synergy of multiple energy sources can be realized,while the swing braking energy can be recovered and used by means of hydraulic energy.Additionally,considering the system constraints and comprehensive optimization conditions of energy efficiency and dynamic characteristics,an improved multi-objective particle swarm optimization(IMOPSO)combined with an adaptive grid is proposed for parameter optimization of the SSEHS.Meanwhile,a parameter rule-based control strategy is designed,which can switch to a reasonable working mode according to the real-time state.Finally,a physical prototype of a 50-t excavator and its AMESim model is established.The semi-simulation and semi-experiment results demonstrate that compared with a conventional swing system,energy consumption under the 90°rotation condition could be reduced by about 51.4%in the SSEHS before parameter optimization,while the energy-saving efficiency is improved by another 13.2%after parameter optimization.This confirms the effectiveness of the SSEHS and the IMOPSO parameter optimization method proposed in this paper.The IMOPSO algorithm is universal and can be used for parameter matching and optimization of hybrid power systems.展开更多
Temperature-swing adsorption(TSA)is an effective technique for CO_(2) capture,but the temperature swing procedure is energy-intensive.Herein,we report a low-energy-consumption system by combining passive radiative coo...Temperature-swing adsorption(TSA)is an effective technique for CO_(2) capture,but the temperature swing procedure is energy-intensive.Herein,we report a low-energy-consumption system by combining passive radiative cooling and solar heating for the uptake of CO_(2) on commercial activated carbons(CACs).During adsorption,the adsorbents are coated with a layer of hierarchically porous poly(vinylidene fluoride-co-hexafluoropropene)[P(VdF-HFP)HP],which cools the adsorbents to a low temperature under sunlight through radiative cooling.For desorption,CACs with broad absorption of the solar spectrum are exposed to light irradiation for heating.The heating and cooling processes are completely driven by solar energy.Adsorption tests under mimicked sunlight using the CACs show that the performance of this system is comparable to that of the traditional ones.Furthermore,under real sunlight irradiation,the adsorption capacity of the CACs can be well maintained after multiple cycles.The present work may inspire the development of new temperature swing procedures with little energy consumption.展开更多
In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperatur...In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.展开更多
This paper delves into the comparative study of tray and packed column pressure swing distillation systems, focusing on the separation of a ternary mixture containing ethanol, tetrahydrofuran (THF), and water. The stu...This paper delves into the comparative study of tray and packed column pressure swing distillation systems, focusing on the separation of a ternary mixture containing ethanol, tetrahydrofuran (THF), and water. The study particularly emphasizes the production of 99.5 w/w% tetrahydrofuran from the downstream product of 1,4-butanediol synthesis via diethyl maleate. Pro/II simulation software is utilized to explore various system configurations, including sieve trays, valve trays, and packed columns. Material and energy balances are performed to ascertain stream compositions and energy demands. The investigation encompasses the effects of column operating pressure on condenser and reboiler temperatures, as well as the implications of utility streams. A rigorous distillation model is employed to compare valve tray, sieve tray, and random packing (utilizing Norton Super Intalox) column designs by varying the number of trays, reflux ratio, and second distillation column pressure. Heat exchangers are integrated into the model, and their areas and utility flow rates are computed and integrated into the economic assessment. Economic analysis, guided by Net Present Value (NPV) calculations over a 20-year span, drives the selection of the most cost-effective design. Results demonstrate that while all designs are energy-efficient, the packed column system emerges as the most economical choice, offering a comprehensive framework for the separation process. Furthermore, optimal design configurations and operating conditions for both tray and packed column systems are outlined, providing valuable insights for industrial applications.展开更多
针对四旋翼无人机吊挂系统的负载摆动抑制和轨迹跟踪问题,提出一种线性自抗扰控制器(Liner Active Disturbance Rejection Controller,LADRC)的轨迹跟踪控制方法。首先,考虑到四旋翼吊挂负载耦合飞行的未知外界扰动与模型的动态不确定性...针对四旋翼无人机吊挂系统的负载摆动抑制和轨迹跟踪问题,提出一种线性自抗扰控制器(Liner Active Disturbance Rejection Controller,LADRC)的轨迹跟踪控制方法。首先,考虑到四旋翼吊挂负载耦合飞行的未知外界扰动与模型的动态不确定性,为飞行器的姿态、位置设计线性自抗扰控制器,通过扩张状态观测器(Extended State Observer,ESO)观测负载摆动和环境干扰对机体的扰动,并对控制量进行相应补偿,来抑制外界和负载摆动给机体带来的干扰,保证无人机飞行过程中的稳定性。其次,针对四旋翼无人机吊挂系统在飞行过程中负载摆角过大的问题,设计加速度规划摆角抑制算法,通过摆角的实时反馈对四旋翼无人机的位置轨迹输入进行路径规划,实现飞行过程中负载摆动的抑制。最后,通过仿真结果证明该控制方法对飞行器的位置及姿态控制效果较好,同时验证了所提的轨迹规划方法能够有效抑制吊挂物的摆动,且对干扰的鲁棒性较强。展开更多
巡检机器人在风载荷作用下会发生一定的摆动,从而导致巡检结果准确性和可靠性降低,参考旋翼类飞行器设计了巡检机器人在风载荷下的平衡机构.首先,利用电机的动力学方程推导电机电压和转速之间的传递函数,使用叶素法建立旋翼产生的升力...巡检机器人在风载荷作用下会发生一定的摆动,从而导致巡检结果准确性和可靠性降低,参考旋翼类飞行器设计了巡检机器人在风载荷下的平衡机构.首先,利用电机的动力学方程推导电机电压和转速之间的传递函数,使用叶素法建立旋翼产生的升力与旋翼转速之间的关系,从而建立平衡机构的输入电压和输出升力之间的联系.其次,分析不同方向的风载荷对巡检机器人工作状态的影响,建立了巡检机器人在横向风载荷下的摆动数学模型.最后,将模糊PID(proportional integral derivative)应用于平衡机构的控制中,开展了巡检机器人的数值仿真和样机实验.结果表明:所设计的平衡机构可以有效抑制巡检机器人在风载荷中的摆动.展开更多
How multi-unmanned aerial vehicles(UAVs)carrying a payload pass an obstacle-dense environment is practically important.Up to now,there have been few results on safe motion planning for the multi-UAVs cooperative trans...How multi-unmanned aerial vehicles(UAVs)carrying a payload pass an obstacle-dense environment is practically important.Up to now,there have been few results on safe motion planning for the multi-UAVs cooperative transportation system(CTS)to pass through such an environment.The prob-lem is challenging because it is difficult to analyze and explicitly take into account the swing motion of the payload in planning.In this paper,a modeling method of virtual tube is proposed by fus-ing the advantages of the existing modeling algorithm for regu-lar virtual tube and the expansion environment method.The pro-posed method can not only generate a safe and smooth tube for UAVs,but also ensure the payload stays away from the dense obstacles.Simulation results show the effectiveness of the method and the safety of the planned tube.展开更多
基金supported by Australia Research Council through the Linkage Project(Grant No.LP200100110).
文摘Swing nose crossings(SNXs)have been widely used in heavy haul railways to create a smoother load transfer and hence reduced impact load.However,the current design of SNXs hasn’t been fully examined under heavy haul operating conditions.Additionally,maintenance guidelines for SNX wear-related issues in Australian heavy haul railways are relatively lacking.As such,this study aims to investigate the dynamic response of the wheel-rail contact and analyse the wear performance of an SNX currently used in Australian heavy haul railways.Dynamic implicit-explicit finite element analysis was conducted to simulate the wheel-rail contact along the SNX.The distribution of the wear intensity over the SNX was identified by using a local contact-based wear model.The influence of various scenarios on wear was also explored.The results verify the improved dynamic performance of the SNX,as the increased contact force after load transfer remains below 1.2 times the static load.The findings also indicate that the decrease in relative height and increase in nose rail inclination result in greater wear on the nose rail.Notably,the SNX considered in the current study exhibits better wear performance when used with moderately worn wheels.
基金supported by the Changsha Major Science and Technology Plan Project,China(No.kq2207002)the Natural Science Foundation of Hunan Province(No.2023JJ40720)the Postgraduate Innovative Project of Central South University,China(No.2022XQLH058)。
文摘In this study,a novel synergistic swing energy-regenerative hybrid system(SSEHS)for excavators with a large inertia slewing platform is constructed.With the SSEHS,the pressure boosting and output energy synergy of multiple energy sources can be realized,while the swing braking energy can be recovered and used by means of hydraulic energy.Additionally,considering the system constraints and comprehensive optimization conditions of energy efficiency and dynamic characteristics,an improved multi-objective particle swarm optimization(IMOPSO)combined with an adaptive grid is proposed for parameter optimization of the SSEHS.Meanwhile,a parameter rule-based control strategy is designed,which can switch to a reasonable working mode according to the real-time state.Finally,a physical prototype of a 50-t excavator and its AMESim model is established.The semi-simulation and semi-experiment results demonstrate that compared with a conventional swing system,energy consumption under the 90°rotation condition could be reduced by about 51.4%in the SSEHS before parameter optimization,while the energy-saving efficiency is improved by another 13.2%after parameter optimization.This confirms the effectiveness of the SSEHS and the IMOPSO parameter optimization method proposed in this paper.The IMOPSO algorithm is universal and can be used for parameter matching and optimization of hybrid power systems.
基金supported by the National Science Fund for Distinguished Young Scholars(22125804)the National Natural Science Foundation of China(21808110,22078155,and 21878149).
文摘Temperature-swing adsorption(TSA)is an effective technique for CO_(2) capture,but the temperature swing procedure is energy-intensive.Herein,we report a low-energy-consumption system by combining passive radiative cooling and solar heating for the uptake of CO_(2) on commercial activated carbons(CACs).During adsorption,the adsorbents are coated with a layer of hierarchically porous poly(vinylidene fluoride-co-hexafluoropropene)[P(VdF-HFP)HP],which cools the adsorbents to a low temperature under sunlight through radiative cooling.For desorption,CACs with broad absorption of the solar spectrum are exposed to light irradiation for heating.The heating and cooling processes are completely driven by solar energy.Adsorption tests under mimicked sunlight using the CACs show that the performance of this system is comparable to that of the traditional ones.Furthermore,under real sunlight irradiation,the adsorption capacity of the CACs can be well maintained after multiple cycles.The present work may inspire the development of new temperature swing procedures with little energy consumption.
基金supported by the National Natural Science Foundation of China(No.62271109)。
文摘In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.
文摘This paper delves into the comparative study of tray and packed column pressure swing distillation systems, focusing on the separation of a ternary mixture containing ethanol, tetrahydrofuran (THF), and water. The study particularly emphasizes the production of 99.5 w/w% tetrahydrofuran from the downstream product of 1,4-butanediol synthesis via diethyl maleate. Pro/II simulation software is utilized to explore various system configurations, including sieve trays, valve trays, and packed columns. Material and energy balances are performed to ascertain stream compositions and energy demands. The investigation encompasses the effects of column operating pressure on condenser and reboiler temperatures, as well as the implications of utility streams. A rigorous distillation model is employed to compare valve tray, sieve tray, and random packing (utilizing Norton Super Intalox) column designs by varying the number of trays, reflux ratio, and second distillation column pressure. Heat exchangers are integrated into the model, and their areas and utility flow rates are computed and integrated into the economic assessment. Economic analysis, guided by Net Present Value (NPV) calculations over a 20-year span, drives the selection of the most cost-effective design. Results demonstrate that while all designs are energy-efficient, the packed column system emerges as the most economical choice, offering a comprehensive framework for the separation process. Furthermore, optimal design configurations and operating conditions for both tray and packed column systems are outlined, providing valuable insights for industrial applications.
文摘针对四旋翼无人机吊挂系统的负载摆动抑制和轨迹跟踪问题,提出一种线性自抗扰控制器(Liner Active Disturbance Rejection Controller,LADRC)的轨迹跟踪控制方法。首先,考虑到四旋翼吊挂负载耦合飞行的未知外界扰动与模型的动态不确定性,为飞行器的姿态、位置设计线性自抗扰控制器,通过扩张状态观测器(Extended State Observer,ESO)观测负载摆动和环境干扰对机体的扰动,并对控制量进行相应补偿,来抑制外界和负载摆动给机体带来的干扰,保证无人机飞行过程中的稳定性。其次,针对四旋翼无人机吊挂系统在飞行过程中负载摆角过大的问题,设计加速度规划摆角抑制算法,通过摆角的实时反馈对四旋翼无人机的位置轨迹输入进行路径规划,实现飞行过程中负载摆动的抑制。最后,通过仿真结果证明该控制方法对飞行器的位置及姿态控制效果较好,同时验证了所提的轨迹规划方法能够有效抑制吊挂物的摆动,且对干扰的鲁棒性较强。
文摘巡检机器人在风载荷作用下会发生一定的摆动,从而导致巡检结果准确性和可靠性降低,参考旋翼类飞行器设计了巡检机器人在风载荷下的平衡机构.首先,利用电机的动力学方程推导电机电压和转速之间的传递函数,使用叶素法建立旋翼产生的升力与旋翼转速之间的关系,从而建立平衡机构的输入电压和输出升力之间的联系.其次,分析不同方向的风载荷对巡检机器人工作状态的影响,建立了巡检机器人在横向风载荷下的摆动数学模型.最后,将模糊PID(proportional integral derivative)应用于平衡机构的控制中,开展了巡检机器人的数值仿真和样机实验.结果表明:所设计的平衡机构可以有效抑制巡检机器人在风载荷中的摆动.
基金supported by the National Natural Science Foundation of China(6237338661973327).
文摘How multi-unmanned aerial vehicles(UAVs)carrying a payload pass an obstacle-dense environment is practically important.Up to now,there have been few results on safe motion planning for the multi-UAVs cooperative transportation system(CTS)to pass through such an environment.The prob-lem is challenging because it is difficult to analyze and explicitly take into account the swing motion of the payload in planning.In this paper,a modeling method of virtual tube is proposed by fus-ing the advantages of the existing modeling algorithm for regu-lar virtual tube and the expansion environment method.The pro-posed method can not only generate a safe and smooth tube for UAVs,but also ensure the payload stays away from the dense obstacles.Simulation results show the effectiveness of the method and the safety of the planned tube.
