Nowadays,more automated or robotic twin-crane systems(RTCSs)are employed in ports and factories to improve material handling efficiency.In a twin-crane system,cranes must travel with a minimum safety distance between ...Nowadays,more automated or robotic twin-crane systems(RTCSs)are employed in ports and factories to improve material handling efficiency.In a twin-crane system,cranes must travel with a minimum safety distance between them to prevent interference.The crane trajectory prediction is critical to interference handling and crane scheduling.Current trajectory predictions lack accuracy because many details are simplified.To enhance accuracy and lessen the trajectory prediction time,a trajectory prediction approach with details(crane acceleration/deceleration,different crane velocities when loading/unloading,and trolley movement)is proposed in this paper.Simulations on different details and their combinations are conducted on a container terminal case study.According to the simulation results,the accuracy of the trajectory prediction can be improved by 20%.The proposed trajectory prediction approach is helpful for building a digital twin of RTCSs and enhancing crane scheduling.展开更多
The supersonic gas-jet target is an important experimental target for laser wakefield acceleration(LWFA),which has great potential for driving novel radiation sources such as betatron radiation and Compton scattering ...The supersonic gas-jet target is an important experimental target for laser wakefield acceleration(LWFA),which has great potential for driving novel radiation sources such as betatron radiation and Compton scattering gamma rays.According to different electron acceleration requirements,it is necessary to provide specific supersonic gas jets with different density profiles to generate electron beams with high quality and high repetition rates.In this study,the interference images and density profiles of different gas-jet targets were obtained through a modified Nomarski interference diagnosis system.The relationships between the gas density and back pressure,nozzle structure,and other key parameters were studied.Targets with different characteristics are conducive to meeting the various requirements of LWFA.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.52075036).
文摘Nowadays,more automated or robotic twin-crane systems(RTCSs)are employed in ports and factories to improve material handling efficiency.In a twin-crane system,cranes must travel with a minimum safety distance between them to prevent interference.The crane trajectory prediction is critical to interference handling and crane scheduling.Current trajectory predictions lack accuracy because many details are simplified.To enhance accuracy and lessen the trajectory prediction time,a trajectory prediction approach with details(crane acceleration/deceleration,different crane velocities when loading/unloading,and trolley movement)is proposed in this paper.Simulations on different details and their combinations are conducted on a container terminal case study.According to the simulation results,the accuracy of the trajectory prediction can be improved by 20%.The proposed trajectory prediction approach is helpful for building a digital twin of RTCSs and enhancing crane scheduling.
基金This work was supported by the Programs for the National Natural Science Foundation of China(Nos.11975316,11775312,12005305 and 61905287)the Continue Basic Scientific Research Project(Nos.WDJC-2019-02 and BJ20002501).
文摘The supersonic gas-jet target is an important experimental target for laser wakefield acceleration(LWFA),which has great potential for driving novel radiation sources such as betatron radiation and Compton scattering gamma rays.According to different electron acceleration requirements,it is necessary to provide specific supersonic gas jets with different density profiles to generate electron beams with high quality and high repetition rates.In this study,the interference images and density profiles of different gas-jet targets were obtained through a modified Nomarski interference diagnosis system.The relationships between the gas density and back pressure,nozzle structure,and other key parameters were studied.Targets with different characteristics are conducive to meeting the various requirements of LWFA.
