Purpose–The purpose of this paper is to optimize the design of charging station deployed at the terminal station for electric transit,with explicit consideration of heterogenous charging modes.Design/methodology/appr...Purpose–The purpose of this paper is to optimize the design of charging station deployed at the terminal station for electric transit,with explicit consideration of heterogenous charging modes.Design/methodology/approach–The authors proposed a bi-level model to optimize the decision-making at both tactical and operational levels simultaneously.Specifically,at the operational level(i.e.lower level),the service schedule and recharging plan of electric buses are optimized under specific design of charging station.The objective of lower-level model is to minimize total daily operational cost.This model is solved by a tailored column generation-based heuristic algorithm.At the tactical level(i.e.upper level),the design of charging station is optimized based upon the results obtained at the lower level.A tabu search algorithm is proposed subsequently to solve the upper-level model.Findings–This study conducted numerical cases to validate the applicability of the proposed model.Some managerial insights stemmed from numerical case studies are revealed and discussed,which can help transit agencies design charging station scientifically.Originality/value–The joint consideration of heterogeneous charging modes in charging station would further lower the operational cost of electric transit and speed up the market penetration of battery electric buses.展开更多
We present a high-performance terahertz(THz)radiation source based on the photon-activated charge domain(PACD)quenched mode of GaAs photoconductive antennas(GaAs PCA).The THz radiation characteristics of the GaAs PCA ...We present a high-performance terahertz(THz)radiation source based on the photon-activated charge domain(PACD)quenched mode of GaAs photoconductive antennas(GaAs PCA).The THz radiation characteristics of the GaAs PCA under different operating modes are studied.Compared with the linear mode,the intensity of THz wave radiated by the GaAs PCA can be greatly enhanced due to the avalanche multiplication effect of carriers in the PACD quenched mode.The results show that when the carrier multiplication ratio is 16.92,the peak-to-peak value of THz field radiated in the PACD quenched mode increases by as much as about 4.19 times compared to the maximum values in the linear mode.展开更多
Overcharging is an important safety issue in the charging process of electric vehicle power batteries,and can easily lead to accelerated battery aging and serious safety accidents.It is necessary to accurately predict...Overcharging is an important safety issue in the charging process of electric vehicle power batteries,and can easily lead to accelerated battery aging and serious safety accidents.It is necessary to accurately predict the vehicle’s charging time to effectively prevent the battery from overcharging.Due to the complex structure of the battery pack and various charging modes,the traditional charging time prediction method often encounters modeling difficulties and low accuracy.In response to the above problems,data drivers and machine learning theories are applied.On the basis of fully considering the different electric vehicle battery management system(BMS)charging modes,a charging time prediction method with charging mode recognition is proposed.First,an intelligent algorithm based on dynamic weighted density peak clustering(DWDPC)and random forest fusion is proposed to classify vehicle charging modes.Then,on the basis of an improved simplified particle swarm optimization(ISPSO)algorithm,a high-performance charging time prediction method is constructed by fully integrating long short-term memory(LSTM)and a strong tracking filter.Finally,the data run by the actual engineering system are verified for the proposed charging time prediction algorithm.Experimental results show that the new method can effectively distinguish the charging modes of different vehicles,identify the charging characteristics of different electric vehicles,and achieve high prediction accuracy.展开更多
Experiments with the limited space-charge accumulation(LSA) mode of oscillation in a large gap semiinsulating (SI) GaAs photoconductive semiconductor switch(PCSS) are discussed.It has been observed that growth a...Experiments with the limited space-charge accumulation(LSA) mode of oscillation in a large gap semiinsulating (SI) GaAs photoconductive semiconductor switch(PCSS) are discussed.It has been observed that growth and drift of a photo-activated charge domain(PACD) are quenched only when the bias voltage is more than twice the threshold voltage.The original negative resistance characteristics are directly utilized in the LSA mode;during LSA operation the spatial average of the electric field varies over a large portion of the negative differential mobility region of the velocity-electric field characteristic.The work efficiency of an SI GaAs PCSS is remarkably enhanced by electric field excursions into the positive resistance region when the total electric field is only below the threshold part of the time.The LSA mode can only operate in the certain conditions that satisfy the quenching of the accumulation layer and the smaller initial domain voltage.展开更多
A double-stage start-up structure to limit the inrush current used in current-mode charge pump with wide input range,fixed output and multimode operation is presented in this paper.As a widely utilized power source im...A double-stage start-up structure to limit the inrush current used in current-mode charge pump with wide input range,fixed output and multimode operation is presented in this paper.As a widely utilized power source implement,a Li-battery is always used as the power supply for chips.Due to the internal resistance,a potential drop will be generated at the input terminal of the chip with an input current.A false shut down with a low supply voltage will happen if the input current is too large,leading to the degradation of the Li-battery's service life.To solve this problem,the inrush current is limited by introducing a new start-up state.All of the circuits have been implemented with the NUVOTON 0.6 μm CMOS process.The measurement results show that the inrush current can be limited below 1 A within all input supply ranges,and the power efficiency is higher than the conventional structure.展开更多
基金This work is supported by National Natural Science Foundation of China(No.72101115)Natural Science Foundation of Jiangsu(No.BK20210316).
文摘Purpose–The purpose of this paper is to optimize the design of charging station deployed at the terminal station for electric transit,with explicit consideration of heterogenous charging modes.Design/methodology/approach–The authors proposed a bi-level model to optimize the decision-making at both tactical and operational levels simultaneously.Specifically,at the operational level(i.e.lower level),the service schedule and recharging plan of electric buses are optimized under specific design of charging station.The objective of lower-level model is to minimize total daily operational cost.This model is solved by a tailored column generation-based heuristic algorithm.At the tactical level(i.e.upper level),the design of charging station is optimized based upon the results obtained at the lower level.A tabu search algorithm is proposed subsequently to solve the upper-level model.Findings–This study conducted numerical cases to validate the applicability of the proposed model.Some managerial insights stemmed from numerical case studies are revealed and discussed,which can help transit agencies design charging station scientifically.Originality/value–The joint consideration of heterogeneous charging modes in charging station would further lower the operational cost of electric transit and speed up the market penetration of battery electric buses.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0701005)the National Natural Science Foundation of China(Grant Nos.61427814 and 51807161)the Natural Science Foundation of Shaanxi Province,China(Grant No.2019JZ-04).
文摘We present a high-performance terahertz(THz)radiation source based on the photon-activated charge domain(PACD)quenched mode of GaAs photoconductive antennas(GaAs PCA).The THz radiation characteristics of the GaAs PCA under different operating modes are studied.Compared with the linear mode,the intensity of THz wave radiated by the GaAs PCA can be greatly enhanced due to the avalanche multiplication effect of carriers in the PACD quenched mode.The results show that when the carrier multiplication ratio is 16.92,the peak-to-peak value of THz field radiated in the PACD quenched mode increases by as much as about 4.19 times compared to the maximum values in the linear mode.
文摘Overcharging is an important safety issue in the charging process of electric vehicle power batteries,and can easily lead to accelerated battery aging and serious safety accidents.It is necessary to accurately predict the vehicle’s charging time to effectively prevent the battery from overcharging.Due to the complex structure of the battery pack and various charging modes,the traditional charging time prediction method often encounters modeling difficulties and low accuracy.In response to the above problems,data drivers and machine learning theories are applied.On the basis of fully considering the different electric vehicle battery management system(BMS)charging modes,a charging time prediction method with charging mode recognition is proposed.First,an intelligent algorithm based on dynamic weighted density peak clustering(DWDPC)and random forest fusion is proposed to classify vehicle charging modes.Then,on the basis of an improved simplified particle swarm optimization(ISPSO)algorithm,a high-performance charging time prediction method is constructed by fully integrating long short-term memory(LSTM)and a strong tracking filter.Finally,the data run by the actual engineering system are verified for the proposed charging time prediction algorithm.Experimental results show that the new method can effectively distinguish the charging modes of different vehicles,identify the charging characteristics of different electric vehicles,and achieve high prediction accuracy.
基金Project supported by the National Natural Science Foundation of China(Nos.50837005,11204264)the Research Fund for Doctors of Xinjiang Normal University(No.XJNUBS 1220)the Research Fund for the Outstanding Young Teacher of Xinjiang Normal University (No.XJNU1214)
文摘Experiments with the limited space-charge accumulation(LSA) mode of oscillation in a large gap semiinsulating (SI) GaAs photoconductive semiconductor switch(PCSS) are discussed.It has been observed that growth and drift of a photo-activated charge domain(PACD) are quenched only when the bias voltage is more than twice the threshold voltage.The original negative resistance characteristics are directly utilized in the LSA mode;during LSA operation the spatial average of the electric field varies over a large portion of the negative differential mobility region of the velocity-electric field characteristic.The work efficiency of an SI GaAs PCSS is remarkably enhanced by electric field excursions into the positive resistance region when the total electric field is only below the threshold part of the time.The LSA mode can only operate in the certain conditions that satisfy the quenching of the accumulation layer and the smaller initial domain voltage.
基金supported by the National Natural Science Foundation of China(No.61106026)
文摘A double-stage start-up structure to limit the inrush current used in current-mode charge pump with wide input range,fixed output and multimode operation is presented in this paper.As a widely utilized power source implement,a Li-battery is always used as the power supply for chips.Due to the internal resistance,a potential drop will be generated at the input terminal of the chip with an input current.A false shut down with a low supply voltage will happen if the input current is too large,leading to the degradation of the Li-battery's service life.To solve this problem,the inrush current is limited by introducing a new start-up state.All of the circuits have been implemented with the NUVOTON 0.6 μm CMOS process.The measurement results show that the inrush current can be limited below 1 A within all input supply ranges,and the power efficiency is higher than the conventional structure.