Autonomous underwater vehicle(AUV)-assisted data collection is an efficient approach to implementing smart ocean.However,the data collection in time-varying ocean currents is plagued by two critical issues:AUV yaw and...Autonomous underwater vehicle(AUV)-assisted data collection is an efficient approach to implementing smart ocean.However,the data collection in time-varying ocean currents is plagued by two critical issues:AUV yaw and sensor node movement.We propose an adaptive AUV-assisted data collection strategy for ocean currents to address these issues.First,we consider the energy consumption of an AUV in conjunction with the value of information(VoI)over the sensor nodes and formulate an optimization problem to maximize the VoI-energy ratio.The AUV yaw problem is then solved by deriving the AUV's reachable region in different ocean current environments and the optimal cruising direction to the target nodes.Finally,using the predicted VoI-energy ratio,we sequentially design a distributed path planning algorithm to select the next target node for AUV.The simulation results indicate that the proposed strategy can utilize ocean currents to aid AUV navigation,thereby reducing the AUV's energy consumption and ensuring timely data collection.展开更多
Appropriate interaction between pantograph and catenary is imperative for smooth operation of electric trains.Changing heights of overhead lines to accommodate level crossings,overbridges,and tunnels pose significant ...Appropriate interaction between pantograph and catenary is imperative for smooth operation of electric trains.Changing heights of overhead lines to accommodate level crossings,overbridges,and tunnels pose significant challenges in maintaining consistent current collection performance as the pantograph aerodynamic profile,and thus aerodynamic load changes significantly with operational height.This research aims to analyse the global flow characteristics and aerodynamic forces acting on individual components of an HSX pantograph operating in different configurations and orientations,such that the results can be combined with multibody simulations to obtain accurate dynamic insight into contact forces.Specifically,computational fluid dynamics simulations are used to investigate the pantograph component loads in a representative setting,such as that of the recessed cavity on a Class 800 train.From an aerodynamic perspective,this study indicates that the total drag force acting on non-fixed components of the pantograph is larger for the knuckle-leading orientation rather than the knuckle-trailing,although the difference between the two is found to reduce with increasing pantograph extension.Combining the aerodynamic loads acting on individual components with multibody tools allows for realistic dynamic insight into the pantograph behaviour.The results obtained show how considering aerodynamic forces enhance the realism of the models,leading to behaviour of the pantograph-catenary contact forces closely matching that seen in experimental tests.展开更多
The characteristics of the triggered vacuum switch （TVS） are obviously influenced by the emission current ie and emission charge of the trigger device. In this paper, an RC charge collector is designed, and the char...The characteristics of the triggered vacuum switch （TVS） are obviously influenced by the emission current ie and emission charge of the trigger device. In this paper, an RC charge collector is designed, and the characteristics of emission current ie and collecting charge Qc of the trigger device are studied. The experimental results indicate that the emission current ie which is produced by the initial plasma has both positive and negative components, and the polarity of the emission current ie depends mainly on the polarity of the bias voltage UBias. The emission current ie and collecting charge Qe increase with the increase of the trigger voltage Utr and the bias voltage UBias. The emission efficient r] increases linearly with the increase of the bias voltage UBias. When the gap distance is 15 mm and bias voltage UBias is 160 V and trigger voltage Utr is 2.6 kV, the emission efficiency r/reaches 6%展开更多
基金supported by the National Natural Science Foundation of China(62071472,62101556)the Natural Science Foundation of Jiangsu province(BK20200650,BK20210489)the Future Network Scientific Research Fund Project(FNSRFP2021-YB-12)。
文摘Autonomous underwater vehicle(AUV)-assisted data collection is an efficient approach to implementing smart ocean.However,the data collection in time-varying ocean currents is plagued by two critical issues:AUV yaw and sensor node movement.We propose an adaptive AUV-assisted data collection strategy for ocean currents to address these issues.First,we consider the energy consumption of an AUV in conjunction with the value of information(VoI)over the sensor nodes and formulate an optimization problem to maximize the VoI-energy ratio.The AUV yaw problem is then solved by deriving the AUV's reachable region in different ocean current environments and the optimal cruising direction to the target nodes.Finally,using the predicted VoI-energy ratio,we sequentially design a distributed path planning algorithm to select the next target node for AUV.The simulation results indicate that the proposed strategy can utilize ocean currents to aid AUV navigation,thereby reducing the AUV's energy consumption and ensuring timely data collection.
基金support of RSSB to this work via the project RSSB/COF-UOH-49 is greatly appreciated.The authors also acknowledge the support by FCT,through IDMEC,under LAETA,project UIDB/50022/2020.
文摘Appropriate interaction between pantograph and catenary is imperative for smooth operation of electric trains.Changing heights of overhead lines to accommodate level crossings,overbridges,and tunnels pose significant challenges in maintaining consistent current collection performance as the pantograph aerodynamic profile,and thus aerodynamic load changes significantly with operational height.This research aims to analyse the global flow characteristics and aerodynamic forces acting on individual components of an HSX pantograph operating in different configurations and orientations,such that the results can be combined with multibody simulations to obtain accurate dynamic insight into contact forces.Specifically,computational fluid dynamics simulations are used to investigate the pantograph component loads in a representative setting,such as that of the recessed cavity on a Class 800 train.From an aerodynamic perspective,this study indicates that the total drag force acting on non-fixed components of the pantograph is larger for the knuckle-leading orientation rather than the knuckle-trailing,although the difference between the two is found to reduce with increasing pantograph extension.Combining the aerodynamic loads acting on individual components with multibody tools allows for realistic dynamic insight into the pantograph behaviour.The results obtained show how considering aerodynamic forces enhance the realism of the models,leading to behaviour of the pantograph-catenary contact forces closely matching that seen in experimental tests.
基金supported by National Natural Science Foundation of China(No.51177131)the Fundamental Research Funds for the Central Universities of China(No.xjj20100159)
文摘The characteristics of the triggered vacuum switch （TVS） are obviously influenced by the emission current ie and emission charge of the trigger device. In this paper, an RC charge collector is designed, and the characteristics of emission current ie and collecting charge Qc of the trigger device are studied. The experimental results indicate that the emission current ie which is produced by the initial plasma has both positive and negative components, and the polarity of the emission current ie depends mainly on the polarity of the bias voltage UBias. The emission current ie and collecting charge Qe increase with the increase of the trigger voltage Utr and the bias voltage UBias. The emission efficient r] increases linearly with the increase of the bias voltage UBias. When the gap distance is 15 mm and bias voltage UBias is 160 V and trigger voltage Utr is 2.6 kV, the emission efficiency r/reaches 6%
