This paper introduces drift analysis approach in studying the convergence and hitting times of evolutionary algorithms. First the methodology of drift analysis is introduced, which links evolutionary algorithms with M...This paper introduces drift analysis approach in studying the convergence and hitting times of evolutionary algorithms. First the methodology of drift analysis is introduced, which links evolutionary algorithms with Markov chains or supermartingales. Then the drift conditions which guarantee the convergence of evolutionary algorithms are described. And next the drift conditions which are used to estimate the hitting times of evolutionary algorithms are presented. Finally an example is given to show how to analyse hitting times of EAs by drift analysis approach.展开更多
In this paper,we consider weak horseshoe with bounded-gap-hitting times.For a flow(M,Ф),it is shown that if the time one map(M,Ф_(1))has weak horseshoe with boundedgap-hitting times,so is(M,Ф_(τ))for all τ≠0.In ...In this paper,we consider weak horseshoe with bounded-gap-hitting times.For a flow(M,Ф),it is shown that if the time one map(M,Ф_(1))has weak horseshoe with boundedgap-hitting times,so is(M,Ф_(τ))for all τ≠0.In addition,we prove that for an affine homeomorphism of a compact metric abelian group,positive topological entropy is equivalent to weak horseshoe with bounded-gap-hitting times.展开更多
Based on an explicit representation of moments of hitting times for single death processes, the criteria on ergodicity and strong ergodicity are obtained. These results can be applied for an extended class of branchin...Based on an explicit representation of moments of hitting times for single death processes, the criteria on ergodicity and strong ergodicity are obtained. These results can be applied for an extended class of branching processes. Meanwhile, some sufficient and necessary conditions for recurrence and exponential ergodicity as well as extinction probability for the processes are presented.展开更多
As the key part of Prognostics and Health Management(PHM), Remaining Useful Life(RUL) estimation has been extensively investigated in recent years. Current RUL estimation studies considering the intervention of im...As the key part of Prognostics and Health Management(PHM), Remaining Useful Life(RUL) estimation has been extensively investigated in recent years. Current RUL estimation studies considering the intervention of imperfect maintenance activities usually assumed that maintenance activities have a single influence on the degradation level or degradation rate, but not on both.Aimed at this problem, this paper proposes a new degradation modeling and RUL estimation method taking the influence of imperfect maintenance activities on both the degradation level and the degradation rate into account. Toward this end, a stochastic degradation model considering imperfect maintenance activities is firstly constructed based on the diffusion process. Then, the Probability Density Function(PDF) of the RUL is derived by the convolution operator under the concept of First Hitting Time(FHT). To implement the proposed RUL estimation method,the Maximum Likelihood Estimation(MLE) is utilized to estimate the degradation related parameters based on the Condition Monitoring(CM) data, while the Bayesian method is utilized to estimate the maintenance related parameters based on the maintenance data. Finally, a numerical example and a practical case study are provided to demonstrate the superiority of the proposed method. The experimental results show that the proposed method could greatly improve the RUL estimation accuracy for the degrading equipment subjected to imperfect maintenance activities.展开更多
Background:The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment designed to measure the neutrino mass hierarchy using a central detector(CD),which contains 20 kton liquid scintilla...Background:The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment designed to measure the neutrino mass hierarchy using a central detector(CD),which contains 20 kton liquid scintillator(LS)surrounded by about 18,000 photomultiplier tubes(PMTs),located 700 m underground.Purpose:The rate of cosmic muons reaching the JUNO detector is about 3 Hz,and the muon-induced neutrons and isotopes are major backgrounds for the neutrino detection.Reconstruction of the muon trajectory in the detector is crucial for the study and rejection of those backgrounds.Methods:This paper will introduce the muon-tracking algorithm in the JUNO CD,with a least-squares method of PMTs’first-hit time(FHT).Correction of the FHT for each PMT was found to be important to reduce the reconstruction bias.Results:The spatial resolution and angular resolution are better than 3 cm and 0.4 degree,respectively,and the tracking efficiency is greater than 90%up to 16 m far from the detector center.展开更多
Controller area network(CAN) based fieldbus technologies have been widely used in networked manufacturing systems. As the information channel of the system, the reliability of the network is crucial to the system thro...Controller area network(CAN) based fieldbus technologies have been widely used in networked manufacturing systems. As the information channel of the system, the reliability of the network is crucial to the system throughput, product quality, and work crew safety. However, due to the inaccessibility of the nodes' internal states, direct assessment of the reliability of CAN nodes using the nodes' internal error counters is infeasible. In this paper, a novel CAN node reliability assessment method, which uses node's time to bus-off as the reliability measure, is proposed. The method estimates the transmit error counter(TEC) of any node in the network based on the network error log and the information provided by the observable nodes whose error counters are accessible.First, a node TEC estimation model is established based on segmented Markov chains. It considers the sparseness of the distribution of the CAN network errors. Second, by learning the differences between the model estimates and the actual values from the observable node, a Bayesian network is developed for the estimation updating mechanism of the observable nodes. Then, this estimation updating mechanism is transferred to general CAN nodes with no TEC value accessibility to update the TEC estimation. Finally, a node reliability assessment method is developed to predict the time to reach bus-off state of the nodes. Case studies are carried out to demonstrate the effectiveness of the proposed methodology. Experimental results show that the estimates using the proposed model agree well with actual observations.展开更多
The criteria on separation cutoff for birth and death chains were obtained by Diaconis and Saloff-Coste in 2006. These criteria are involving all eigenvalues. In this paper, we obtain the explicit criterion, which dep...The criteria on separation cutoff for birth and death chains were obtained by Diaconis and Saloff-Coste in 2006. These criteria are involving all eigenvalues. In this paper, we obtain the explicit criterion, which depends only on the birth and death rates. Furthermore, we present two ways to estimate moments of the fastest strong stationary time and then give another but equivalent criterion explicitly.展开更多
For the birth–death Q-matrix with regular boundary,its minimal process and its maximal process are closely related.In this paper,we obtain the uniform decay rate and the quasi-stationary distribution for the minimal ...For the birth–death Q-matrix with regular boundary,its minimal process and its maximal process are closely related.In this paper,we obtain the uniform decay rate and the quasi-stationary distribution for the minimal process.And via the construction theory,we mainly derive the eigentime identity and the distribution of the fastest strong stationary time(FSST)for the maximal process.展开更多
This paper treats of the range of the simple random walk on trees and a related trapping problem. The strong law of large numbers and the central limit theorem for the range, and some asymptotic behaviour for the mean...This paper treats of the range of the simple random walk on trees and a related trapping problem. The strong law of large numbers and the central limit theorem for the range, and some asymptotic behaviour for the mean trapping time and survival probability are presented.展开更多
基金Supported by Engineering and Physical Science Research Courcil(GR/R52541/01)and State Laboratory of Software Engineering at Wuhan University
文摘This paper introduces drift analysis approach in studying the convergence and hitting times of evolutionary algorithms. First the methodology of drift analysis is introduced, which links evolutionary algorithms with Markov chains or supermartingales. Then the drift conditions which guarantee the convergence of evolutionary algorithms are described. And next the drift conditions which are used to estimate the hitting times of evolutionary algorithms are presented. Finally an example is given to show how to analyse hitting times of EAs by drift analysis approach.
基金Leiye Xu is partially supported by NNSF of China(11801538,11871188)the USTC Research Funds of the Double First-Class Initiative.Junren Zheng is partially supported by NNSF of China(11971455).
文摘In this paper,we consider weak horseshoe with bounded-gap-hitting times.For a flow(M,Ф),it is shown that if the time one map(M,Ф_(1))has weak horseshoe with boundedgap-hitting times,so is(M,Ф_(τ))for all τ≠0.In addition,we prove that for an affine homeomorphism of a compact metric abelian group,positive topological entropy is equivalent to weak horseshoe with bounded-gap-hitting times.
文摘Based on an explicit representation of moments of hitting times for single death processes, the criteria on ergodicity and strong ergodicity are obtained. These results can be applied for an extended class of branching processes. Meanwhile, some sufficient and necessary conditions for recurrence and exponential ergodicity as well as extinction probability for the processes are presented.
基金co-supported by the National Science Foundation of China(NSFC)(Nos.61573365,61603398,61374126,61473094,and 61773386)the Young Talent Fund of University Association for Science and Technology in Shaanxi,Chinathe Young Elite Scientists Sponsorship Program(YESS)by China Association for Science and Technology(CAST)
文摘As the key part of Prognostics and Health Management(PHM), Remaining Useful Life(RUL) estimation has been extensively investigated in recent years. Current RUL estimation studies considering the intervention of imperfect maintenance activities usually assumed that maintenance activities have a single influence on the degradation level or degradation rate, but not on both.Aimed at this problem, this paper proposes a new degradation modeling and RUL estimation method taking the influence of imperfect maintenance activities on both the degradation level and the degradation rate into account. Toward this end, a stochastic degradation model considering imperfect maintenance activities is firstly constructed based on the diffusion process. Then, the Probability Density Function(PDF) of the RUL is derived by the convolution operator under the concept of First Hitting Time(FHT). To implement the proposed RUL estimation method,the Maximum Likelihood Estimation(MLE) is utilized to estimate the degradation related parameters based on the Condition Monitoring(CM) data, while the Bayesian method is utilized to estimate the maintenance related parameters based on the maintenance data. Finally, a numerical example and a practical case study are provided to demonstrate the superiority of the proposed method. The experimental results show that the proposed method could greatly improve the RUL estimation accuracy for the degrading equipment subjected to imperfect maintenance activities.
基金This work is supported by National Natural Science Foundation of China(Grant Nos.11575226,11605222)Joint Large Scale Scientific Facility Funds of NSFC and CAS(Grant No.U1532258)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA10010900)。
文摘Background:The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment designed to measure the neutrino mass hierarchy using a central detector(CD),which contains 20 kton liquid scintillator(LS)surrounded by about 18,000 photomultiplier tubes(PMTs),located 700 m underground.Purpose:The rate of cosmic muons reaching the JUNO detector is about 3 Hz,and the muon-induced neutrons and isotopes are major backgrounds for the neutrino detection.Reconstruction of the muon trajectory in the detector is crucial for the study and rejection of those backgrounds.Methods:This paper will introduce the muon-tracking algorithm in the JUNO CD,with a least-squares method of PMTs’first-hit time(FHT).Correction of the FHT for each PMT was found to be important to reduce the reconstruction bias.Results:The spatial resolution and angular resolution are better than 3 cm and 0.4 degree,respectively,and the tracking efficiency is greater than 90%up to 16 m far from the detector center.
基金Project supported by the National Natural Science Foundation of China(Nos.51475422 and 51521064)the National Basic Research Program(973)of China(No.2013CB035405)
文摘Controller area network(CAN) based fieldbus technologies have been widely used in networked manufacturing systems. As the information channel of the system, the reliability of the network is crucial to the system throughput, product quality, and work crew safety. However, due to the inaccessibility of the nodes' internal states, direct assessment of the reliability of CAN nodes using the nodes' internal error counters is infeasible. In this paper, a novel CAN node reliability assessment method, which uses node's time to bus-off as the reliability measure, is proposed. The method estimates the transmit error counter(TEC) of any node in the network based on the network error log and the information provided by the observable nodes whose error counters are accessible.First, a node TEC estimation model is established based on segmented Markov chains. It considers the sparseness of the distribution of the CAN network errors. Second, by learning the differences between the model estimates and the actual values from the observable node, a Bayesian network is developed for the estimation updating mechanism of the observable nodes. Then, this estimation updating mechanism is transferred to general CAN nodes with no TEC value accessibility to update the TEC estimation. Finally, a node reliability assessment method is developed to predict the time to reach bus-off state of the nodes. Case studies are carried out to demonstrate the effectiveness of the proposed methodology. Experimental results show that the estimates using the proposed model agree well with actual observations.
基金Acknowledgements This work was supported in part by 985 Project, 973 Project (No. 2011CB808000), the National Natural Science Foundation of China (Grant No. 11131003), the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20100003110005), and the Fundamental Research Funds for the Central Universities.
文摘The criteria on separation cutoff for birth and death chains were obtained by Diaconis and Saloff-Coste in 2006. These criteria are involving all eigenvalues. In this paper, we obtain the explicit criterion, which depends only on the birth and death rates. Furthermore, we present two ways to estimate moments of the fastest strong stationary time and then give another but equivalent criterion explicitly.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11501531,11701265,11771047)。
文摘For the birth–death Q-matrix with regular boundary,its minimal process and its maximal process are closely related.In this paper,we obtain the uniform decay rate and the quasi-stationary distribution for the minimal process.And via the construction theory,we mainly derive the eigentime identity and the distribution of the fastest strong stationary time(FSST)for the maximal process.
文摘This paper treats of the range of the simple random walk on trees and a related trapping problem. The strong law of large numbers and the central limit theorem for the range, and some asymptotic behaviour for the mean trapping time and survival probability are presented.