The Balise Transmission Module(BTM)unit of the on-board train control system is a crucial component.Due to its unique installation position and complex environment,this unit has a higher fault rate within the on-board...The Balise Transmission Module(BTM)unit of the on-board train control system is a crucial component.Due to its unique installation position and complex environment,this unit has a higher fault rate within the on-board train control system.To conduct fault prediction for the BTM unit based on actual fault data,this study proposes a prediction method combining reliability statistics and machine learning,and achieves the fusion of prediction results from different dimensions through multi-method interactive validation.Firstly,a method for predicting equipment fault time targeting batch equipment is introduced.This method utilizes reliability statistics to construct a model of the remaining faultless operating time distribution considering uncertainty,thereby predicting the remaining faultless operating probability of the BTM unit.Secondly,considering the complexity of the BTM unit’s fault mechanism,the small sample size of fault cases,and the potential presence of multiple fault features in fault text records,an individual-oriented fault prediction method based on Bayesian-optimized Gradient Boosting Regression Tree(Bayes-GBRT)is proposed.This method achieves better prediction results compared to linear regression algorithms and random forest regression algorithms,with an average absolute error of only 0.224 years for predicting the fault time of this type of equipment.Finally,a multi-method interactive validation approach is proposed,enabling the fusion and validation of multi-dimensional results.The results indicate that the predicted fault time and the actual fault time conform to a log-normal distribution,and the parameter estimation results are basically consistent,verifying the accuracy and effectiveness of the prediction results.The above research findings can provide technical support for the maintenance and modification of BTM units,effectively reducing maintenance costs and ensuring the safe operation of high-speed railway,thus having practical engineering value for preventive maintenance.展开更多
The transmission coefficients of electromagnetic （EM） waves due to a superconductor-dielectric superlattice are numerically calculated. Shift operator finite difference time domain （SO-FDTD） method is used in the ...The transmission coefficients of electromagnetic （EM） waves due to a superconductor-dielectric superlattice are numerically calculated. Shift operator finite difference time domain （SO-FDTD） method is used in the analysis. By using the SO-FDTD method, the transmission spectrum is obtained and its characteristics are investigated for different thicknesses of superconductor layers and dielectric layers, from which a stop band starting from zero frequency can be apparently observed. The relation between this low-frequency stop band and relative temperature, and also the London penetration depth at a superconductor temperature of zero degree are discussed, separately. The low-frequency stop band properties of superconductor-dielectric superlattice thus are well disclosed.展开更多
This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure o...This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model.展开更多
This study quantified the effect of weeding frequency and weeding schedules on weeding operation time in a sugi(Cryptomeria japonica)plantation stand.A weeding operation time estimation model was developed;then the cu...This study quantified the effect of weeding frequency and weeding schedules on weeding operation time in a sugi(Cryptomeria japonica)plantation stand.A weeding operation time estimation model was developed;then the cumulative weeding operation time after six growing seasons was simulated using the developed model.The developed model included weed height,relative height of weeds to sugi,and initial planting density.The simulated cumulative weeding operation time decreased approximately 6%for each one-treatment decrease in weeding frequency.Under a three-treatment weeding frequency scenario,the simulated cumulative operation time when weeding was conducted during non-consecutive years was longer than that when weeding was conducted during three consecutive years.The results suggest that carrying out weeding treatment during consecutive years is the more effective for reduction of weeding costs.We conclude that weeding schedule as well as weeding frequency must be considered for reduction of weeding operation time.展开更多
A clustering algorithm and a probability statistics method were applied to different phases of a flight to analyze operation time during aircraft ground taxiing and airborne flight.And the clustering pattern,distribut...A clustering algorithm and a probability statistics method were applied to different phases of a flight to analyze operation time during aircraft ground taxiing and airborne flight.And the clustering pattern,distribution characteristics and dynamically changing rules of the two phases were identified.Further,an estimate method was established to measure operation time of flight legs,with creative steps of calculating individual segment separately and then integrating them accordingly.The method can both objectively and dynamically measure operation time,and accurately reflect real situation.It helps to better utilize airport slot resources and provides a strong support for air traffic flow management when scheduling flight plan in strategic and pre-tactic phases.展开更多
Properties of an operator representing the dynamical time in the extended parameterization invariant formulation of quantum mechanics are studied. It is shown that this time operator is given by a positive operator me...Properties of an operator representing the dynamical time in the extended parameterization invariant formulation of quantum mechanics are studied. It is shown that this time operator is given by a positive operator measure analogously to the quantities that are known to represent various measurable time operators. The relation between the dynamical time of the extended formulation and the best known example of the system time operator, i.e., for the free one- dimensional particle, is obtained.展开更多
We investigate entanglement of assistance without and with decoherence using a local non-Hermitian operation, i.e.,parity–time(PT) symmetric operation. First we give the explicit expressions of entanglement of assist...We investigate entanglement of assistance without and with decoherence using a local non-Hermitian operation, i.e.,parity–time(PT) symmetric operation. First we give the explicit expressions of entanglement of assistance for a general W-like state of a three-qubit system under a local parity–time symmetric operation. Then for a famous W state without decoherence, we find that entanglement of assistance shared by two parties can be obviously enhanced with the assistance of the third party by a local parity–time symmetric operation. For the decoherence case, we provide two schemes to show the effects of local parity–time symmetric operation on improvement of entanglement of assistance against amplitude damping noise. We find that for the larger amplitude damping case the scheme of PT symmetric operation performed on one of two parties with the influence of noise is superior to that of PT symmetric operation performed on the third party without the influence of noise in suppressing amplitude damping noise. However, for the smaller amplitude damping case the opposite result is given. The obtained results imply that the local PT symmetric operation method may have potential applications in quantum decoherence control.展开更多
We present a non-Markovian master equation for a qubit interacting with a general reservoir, which is derived according to the Nakajima-Zwanzig and the time convolutionless projection operator technique. The non-Marko...We present a non-Markovian master equation for a qubit interacting with a general reservoir, which is derived according to the Nakajima-Zwanzig and the time convolutionless projection operator technique. The non-Markovian solutions and Markovian solution of dynamical decay of a qubit are compared. The results indicate the validity of non-Markovian approach in different coupling regimes and also show that the Markovian master equation may not precisely describe the dynamics of an open quantum system in some situation. The non-Markovian solutions may be effective for many qubits independently interacting with the heated reservoirs.展开更多
The dynamics of two non-coupled qubits independently interacting with their reservoirs is solved by the time convolutionless projection operator method. We study two-qubit quantum correlation dynamics for two differen...The dynamics of two non-coupled qubits independently interacting with their reservoirs is solved by the time convolutionless projection operator method. We study two-qubit quantum correlation dynamics for two different types of spectral densities, which are a Lorentzian distribution and an Ohmic spectral density with a Lorentzian–Drude cutoff function. For two qubits initially prepared in the initial Bell state, quantum discord can keep longer time and reach larger values in nonMarkovian reservoirs for the first spectral distribution or by reducing the cutoff frequency for the second case. For the initial Bell-like state, the dynamic behaviors of quantum discord and entanglement are compared. The results show that a long time of quantum correlation can be obtained by adjusting some parameters in experiment and further confirm that the discord can capture quantum correlation in addition to entanglement.展开更多
We characterized the dependence of the timing jitter of an InGaAs/InP single-photon avalanche diode on the excess bias voltage（V（ex）） when operated in 1-GHz sinusoidally gated mode.The single-photon avalanche diod...We characterized the dependence of the timing jitter of an InGaAs/InP single-photon avalanche diode on the excess bias voltage（V（ex）） when operated in 1-GHz sinusoidally gated mode.The single-photon avalanche diode was cooled to-30 degrees Celsius.When the V（ex） is too low（0.2 V-0.8 V） or too high（3 V-4.2 V）,the timing jitter is increased with the V（ex）,particularly at high V（ex）.While at middle V（ex）（1 V-2.8 V）,the timing jitter is reduced.Measurements of the timing jitter of the same avalanche diode with pulsed gating show that this effect is likely related to the increase of both the amplitude of the V（ex） and the width of the gate-on time.For the 1-GHz sinusoidally gated detector,the best jitter of 93 ps is achieved with a photon detection efficiency of 21.4%and a dark count rate of -2.08×10 -5 per gate at the V（ex） of 2.8 V.To evaluate the whole performance of the detector,we calculated the noise equivalent power（NEP） and the afterpulse probability（P（ap））.It is found that both NEP and P（ap） increase quickly when the V（ex） is above 2.8 V.At -2.8-V V（ex）,the NEP and P（ap） are -2.06×10-（16）W/Hz-（1/2） and 7.11%,respectively.Therefore,the detector should be operated with V（ex） of 2.8 V to exploit the fast time response,low NEP and low P（ap）.展开更多
It has been found that for a fixed degree of fuzziness in the coarsened references of measurements,the quantum-toclassical transition can be observed independent of the macroscopicity of the quantum state.We explore a...It has been found that for a fixed degree of fuzziness in the coarsened references of measurements,the quantum-toclassical transition can be observed independent of the macroscopicity of the quantum state.We explore a general situation that the degree of fuzziness can change with the rotation angle between two states（different rotation angles represent different references）.The fuzziness of reference comes from two kinds of fuzziness：the Hamiltonian（rotation frequency）and the timing（rotation time）.For the fuzziness of the Hamiltonian alone,the degree of fuzziness for the reference will change with the rotation angle between two states,and the quantum effects can still be observed with any degree of fuzziness of Hamiltonian.For the fuzziness of timing,the degree of the coarsening reference is unchanged with the rotation angle.During the rotation of the measurement axis,the decoherence environment can also help the classical-to-quantum transition due to changing the direction of the measurement axis.展开更多
基金supported by the Integrated Rail Transit Dispatch Control and Intermodal Transport Service Technology Project(Grant No.2022YFB4300500).
文摘The Balise Transmission Module(BTM)unit of the on-board train control system is a crucial component.Due to its unique installation position and complex environment,this unit has a higher fault rate within the on-board train control system.To conduct fault prediction for the BTM unit based on actual fault data,this study proposes a prediction method combining reliability statistics and machine learning,and achieves the fusion of prediction results from different dimensions through multi-method interactive validation.Firstly,a method for predicting equipment fault time targeting batch equipment is introduced.This method utilizes reliability statistics to construct a model of the remaining faultless operating time distribution considering uncertainty,thereby predicting the remaining faultless operating probability of the BTM unit.Secondly,considering the complexity of the BTM unit’s fault mechanism,the small sample size of fault cases,and the potential presence of multiple fault features in fault text records,an individual-oriented fault prediction method based on Bayesian-optimized Gradient Boosting Regression Tree(Bayes-GBRT)is proposed.This method achieves better prediction results compared to linear regression algorithms and random forest regression algorithms,with an average absolute error of only 0.224 years for predicting the fault time of this type of equipment.Finally,a multi-method interactive validation approach is proposed,enabling the fusion and validation of multi-dimensional results.The results indicate that the predicted fault time and the actual fault time conform to a log-normal distribution,and the parameter estimation results are basically consistent,verifying the accuracy and effectiveness of the prediction results.The above research findings can provide technical support for the maintenance and modification of BTM units,effectively reducing maintenance costs and ensuring the safe operation of high-speed railway,thus having practical engineering value for preventive maintenance.
基金Project supported partly by the Open Research Program in State Key Laboratory of Millimeter Waves of China(Grant No.K200802)partly by the National Natural Science Foundation of China(Grant No.60971122)
文摘The transmission coefficients of electromagnetic （EM） waves due to a superconductor-dielectric superlattice are numerically calculated. Shift operator finite difference time domain （SO-FDTD） method is used in the analysis. By using the SO-FDTD method, the transmission spectrum is obtained and its characteristics are investigated for different thicknesses of superconductor layers and dielectric layers, from which a stop band starting from zero frequency can be apparently observed. The relation between this low-frequency stop band and relative temperature, and also the London penetration depth at a superconductor temperature of zero degree are discussed, separately. The low-frequency stop band properties of superconductor-dielectric superlattice thus are well disclosed.
基金supported by the State Grid Science and Technology Project (No.52999821N004)。
文摘This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model.
文摘This study quantified the effect of weeding frequency and weeding schedules on weeding operation time in a sugi(Cryptomeria japonica)plantation stand.A weeding operation time estimation model was developed;then the cumulative weeding operation time after six growing seasons was simulated using the developed model.The developed model included weed height,relative height of weeds to sugi,and initial planting density.The simulated cumulative weeding operation time decreased approximately 6%for each one-treatment decrease in weeding frequency.Under a three-treatment weeding frequency scenario,the simulated cumulative operation time when weeding was conducted during non-consecutive years was longer than that when weeding was conducted during three consecutive years.The results suggest that carrying out weeding treatment during consecutive years is the more effective for reduction of weeding costs.We conclude that weeding schedule as well as weeding frequency must be considered for reduction of weeding operation time.
基金supported by the National Natural Science Foundation of China(No.U1333202)
文摘A clustering algorithm and a probability statistics method were applied to different phases of a flight to analyze operation time during aircraft ground taxiing and airborne flight.And the clustering pattern,distribution characteristics and dynamically changing rules of the two phases were identified.Further,an estimate method was established to measure operation time of flight legs,with creative steps of calculating individual segment separately and then integrating them accordingly.The method can both objectively and dynamically measure operation time,and accurately reflect real situation.It helps to better utilize airport slot resources and provides a strong support for air traffic flow management when scheduling flight plan in strategic and pre-tactic phases.
基金Project supported by the Ministry of Science and Education of the Republic of Serbia (Grant Nos. 171017, 171028, and 171006)
文摘Properties of an operator representing the dynamical time in the extended parameterization invariant formulation of quantum mechanics are studied. It is shown that this time operator is given by a positive operator measure analogously to the quantities that are known to represent various measurable time operators. The relation between the dynamical time of the extended formulation and the best known example of the system time operator, i.e., for the free one- dimensional particle, is obtained.
基金Project supported by China Postdoctoral Science Foundation(Grant No.2017M622582)the Natural Science Foundation of Hunan Province of China(Grant No.2015JJ3092)+2 种基金the Research Foundation of Education Bureau of Hunan Province of China(Grant No.16B177)Applied Characteristic Disciplines in Hunan Province-Electronic Science and Technology of ChinaHunan-Provincial Key Laboratory of Photoelectric Information Integration and Optical Manufacturing Technology
文摘We investigate entanglement of assistance without and with decoherence using a local non-Hermitian operation, i.e.,parity–time(PT) symmetric operation. First we give the explicit expressions of entanglement of assistance for a general W-like state of a three-qubit system under a local parity–time symmetric operation. Then for a famous W state without decoherence, we find that entanglement of assistance shared by two parties can be obviously enhanced with the assistance of the third party by a local parity–time symmetric operation. For the decoherence case, we provide two schemes to show the effects of local parity–time symmetric operation on improvement of entanglement of assistance against amplitude damping noise. We find that for the larger amplitude damping case the scheme of PT symmetric operation performed on one of two parties with the influence of noise is superior to that of PT symmetric operation performed on the third party without the influence of noise in suppressing amplitude damping noise. However, for the smaller amplitude damping case the opposite result is given. The obtained results imply that the local PT symmetric operation method may have potential applications in quantum decoherence control.
基金Project supported by the Natural Science Foundation of Hunan Province of China (Grant No. 09JJ6011)the Natural Science Foundation of the Education Department of Hunan Province of China (Grant Nos. 06C652 and 07C528)
文摘We present a non-Markovian master equation for a qubit interacting with a general reservoir, which is derived according to the Nakajima-Zwanzig and the time convolutionless projection operator technique. The non-Markovian solutions and Markovian solution of dynamical decay of a qubit are compared. The results indicate the validity of non-Markovian approach in different coupling regimes and also show that the Markovian master equation may not precisely describe the dynamics of an open quantum system in some situation. The non-Markovian solutions may be effective for many qubits independently interacting with the heated reservoirs.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11264011 and 11104113)the Natural Science Foundation of Hunan Province, China (Grant Nos. 13JJ6059 and 11JJ6007)the Natural Science Foundation of Education Department of Hunan Province, China (GrantNo. 11C1057)
文摘The dynamics of two non-coupled qubits independently interacting with their reservoirs is solved by the time convolutionless projection operator method. We study two-qubit quantum correlation dynamics for two different types of spectral densities, which are a Lorentzian distribution and an Ohmic spectral density with a Lorentzian–Drude cutoff function. For two qubits initially prepared in the initial Bell state, quantum discord can keep longer time and reach larger values in nonMarkovian reservoirs for the first spectral distribution or by reducing the cutoff frequency for the second case. For the initial Bell-like state, the dynamic behaviors of quantum discord and entanglement are compared. The results show that a long time of quantum correlation can be obtained by adjusting some parameters in experiment and further confirm that the discord can capture quantum correlation in addition to entanglement.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11275024,61274024,and 61474123)the Youth Innovation Promotion Association,China(Grant No.2013105)the Ministry of Science and Technology of China(Grant Nos.2013YQ030595-3 and 2011AA120101)
文摘We characterized the dependence of the timing jitter of an InGaAs/InP single-photon avalanche diode on the excess bias voltage（V（ex）） when operated in 1-GHz sinusoidally gated mode.The single-photon avalanche diode was cooled to-30 degrees Celsius.When the V（ex） is too low（0.2 V-0.8 V） or too high（3 V-4.2 V）,the timing jitter is increased with the V（ex）,particularly at high V（ex）.While at middle V（ex）（1 V-2.8 V）,the timing jitter is reduced.Measurements of the timing jitter of the same avalanche diode with pulsed gating show that this effect is likely related to the increase of both the amplitude of the V（ex） and the width of the gate-on time.For the 1-GHz sinusoidally gated detector,the best jitter of 93 ps is achieved with a photon detection efficiency of 21.4%and a dark count rate of -2.08×10 -5 per gate at the V（ex） of 2.8 V.To evaluate the whole performance of the detector,we calculated the noise equivalent power（NEP） and the afterpulse probability（P（ap））.It is found that both NEP and P（ap） increase quickly when the V（ex） is above 2.8 V.At -2.8-V V（ex）,the NEP and P（ap） are -2.06×10-（16）W/Hz-（1/2） and 7.11%,respectively.Therefore,the detector should be operated with V（ex） of 2.8 V to exploit the fast time response,low NEP and low P（ap）.
基金Project supported by the National Natural Science Foundation of China(Grant No.11375168)
文摘It has been found that for a fixed degree of fuzziness in the coarsened references of measurements,the quantum-toclassical transition can be observed independent of the macroscopicity of the quantum state.We explore a general situation that the degree of fuzziness can change with the rotation angle between two states（different rotation angles represent different references）.The fuzziness of reference comes from two kinds of fuzziness：the Hamiltonian（rotation frequency）and the timing（rotation time）.For the fuzziness of the Hamiltonian alone,the degree of fuzziness for the reference will change with the rotation angle between two states,and the quantum effects can still be observed with any degree of fuzziness of Hamiltonian.For the fuzziness of timing,the degree of the coarsening reference is unchanged with the rotation angle.During the rotation of the measurement axis,the decoherence environment can also help the classical-to-quantum transition due to changing the direction of the measurement axis.
