A so-called 'local probabilistic Paris relation method' was presented for measuring the random thresholds of long fatigue crack propagation. A check was made to the conventional method, in which the thresholds...A so-called 'local probabilistic Paris relation method' was presented for measuring the random thresholds of long fatigue crack propagation. A check was made to the conventional method, in which the thresholds were measured statistically and directly by the test data. It was revealed that this method was not reasonable because the test data have seldom a unified level of crack growth rates. Differently,in the presented method the Paris-Erdogan equation was applied to model the local test data around the thresholds. Local probabilistic relations with both the survival probability and the confidence were established on a lognormal distribution of the stress density factors. And then, the probabilistic thresholds were derived from the probabilistic factors with a given critical level of growth rate. An analysis on the test data of LZ50 axle steel for the Chinese railway vehicles verifies that the present method is feasible and available.展开更多
Remaining useful life(RUL) estimation based on condition monitoring data is central to condition based maintenance(CBM). In the current methods about the Wiener process based RUL estimation, the randomness of the fail...Remaining useful life(RUL) estimation based on condition monitoring data is central to condition based maintenance(CBM). In the current methods about the Wiener process based RUL estimation, the randomness of the failure threshold has not been studied thoroughly. In this work, by using the truncated normal distribution to model random failure threshold(RFT), an analytical and closed-form RUL distribution based on the current observed data was derived considering the posterior distribution of the drift parameter. Then, the Bayesian method was used to update the prior estimation of failure threshold. To solve the uncertainty of the censored in situ data of failure threshold, the expectation maximization(EM) algorithm is used to calculate the posteriori estimation of failure threshold. Numerical examples show that considering the randomness of the failure threshold and updating the prior information of RFT could improve the accuracy of real time RUL estimation.展开更多
Remaining useful life(RUL)prediction is one of the most crucial components in prognostics and health management(PHM)of aero-engines.This paper proposes an RUL prediction method of aero-engines considering the randomne...Remaining useful life(RUL)prediction is one of the most crucial components in prognostics and health management(PHM)of aero-engines.This paper proposes an RUL prediction method of aero-engines considering the randomness of failure threshold.Firstly,a random-coefficient regression(RCR)model is used to model the degradation process of aeroengines.Then,the RUL distribution based on fixed failure threshold is derived.The prior parameters of the degradation model are calculated by a two-step maximum likelihood estimation(MLE)method and the random coefficient is updated in real time under the Bayesian framework.The failure threshold in this paper is defined by the actual degradation process of aeroengines.After that,a expectation maximization(EM)algorithm is proposed to estimate the underlying failure threshold of aeroengines.In addition,the conditional probability is used to satisfy the limitation of failure threshold.Then,based on above results,an analytical expression of RUL distribution of aero-engines based on the RCR model considering random failure threshold(RFT)is derived in a closed-form.Finally,a case study of turbofan engine is used to demonstrate the effectiveness and superiority of the RUL prediction method and the parameters estimation method of failure threshold proposed.展开更多
Species evolution is essentially a random process of interaction between biological populations and their environ- ments. As a result, some physical parameters in evolution models are subject to statistical fluctuatio...Species evolution is essentially a random process of interaction between biological populations and their environ- ments. As a result, some physical parameters in evolution models are subject to statistical fluctuations. In this work, two important parameters in the Eigen model, the fitness and mutation rate, are treated as Gaassian dis- tributed random variables simultaneously to examine the property of the error threshold. Numerical simulation results show that the error threshold in the fully random model appears as a crossover region instead of a phase transition point, and ＆s the fluctuation strength increases the crossover region becomes smoother and smoother. Furthermore, it is shown that the randomization of the mutation rate plays a dominant role in changing the error threshold in the fully random model, which is consistent with the existing experimental data. The implication of the threshold change due to the randomization for antiviral strategies is discussed.展开更多
This research paper proposes a filter to remove Random Valued Impulse Noise (RVIN) based on Global Threshold Vector Outlyingness Ratio (GTVOR) that is applicable for real time image processing. This filter works with ...This research paper proposes a filter to remove Random Valued Impulse Noise (RVIN) based on Global Threshold Vector Outlyingness Ratio (GTVOR) that is applicable for real time image processing. This filter works with the algorithm that breaks the images into various decomposition levels using Discrete Wavelet Transform (DWT) and searches for the noisy pixels using the outlyingness of the pixel. This algorithm has the capability of differentiating high frequency pixels and the “noisy pixel” using the threshold as well as window adjustments. The damage and the loss of information are prevented by means of interior mining. This global threshold based algorithm uses different thresholds for different quadrants of DWT and thus helps in recovery of noisy image even if it is 90% affected. Experimental results exhibit that this method outperforms other existing methods for accurate noise detection and removal, at the same time chain of connectivity is not lost.展开更多
In this paper surrogate data method of phase-randomized is proposed to identify the random or chaotic nature of the data obtained in dynamic analysis: The calculating results validate the phase-randomized method to be...In this paper surrogate data method of phase-randomized is proposed to identify the random or chaotic nature of the data obtained in dynamic analysis: The calculating results validate the phase-randomized method to be useful as it can increase the extent of accuracy of the results. And the calculating results show that threshold values of the random timeseries and nonlinear chaotic timeseries have marked difference.展开更多
A method for reliability analysis of the competing failure with the probabilistic failure threshold value not the fixed threshold value is presented, which involves the random shocks and the degradation is independent...A method for reliability analysis of the competing failure with the probabilistic failure threshold value not the fixed threshold value is presented, which involves the random shocks and the degradation is independent and dependent respectively. Specifically, for the dependent condition, the effect due to the random shocks on the degradation is considered with a damage factor. In addition, the dependent competing failure model is applied to the reliability analysis of the k-out-of-n systems. Finally, two studied cases are presented to illustrate the proposed method, and the results show the proposed method is reasonable.展开更多
This work demonstrates the realization of a lasing in scattering media,which contains dispersive solution of Zn O nanoparticles（NPs） and laser dye 4-dicyanomethylene-2-methyle-6-（p-dimethylaminostyryl）-4H-pyran（...This work demonstrates the realization of a lasing in scattering media,which contains dispersive solution of Zn O nanoparticles（NPs） and laser dye 4-dicyanomethylene-2-methyle-6-（p-dimethylaminostyryl）-4H-pyran（DCM） in negative liquid crystals（LCs） that was injected into a cell.The lasing intensity of the dye-doped negative LC laser can be tuned from low to high if the NPs concentration is increased.The tunability of the laser is attributable to the clusters-sensitive feature in effective refractive index of the negative LCs.Such a tunable negative liquid crystal laser can be used in the fabrication of new optical sources,optical communication,and liquid crystal laser displays.展开更多
To tackle the key-exposure problem in signature settings,this paper introduces a new cryptographic primitive named threshold key-insulated signature(TKIS) and proposes a concrete TKIS scheme.For a TKIS system,at least...To tackle the key-exposure problem in signature settings,this paper introduces a new cryptographic primitive named threshold key-insulated signature(TKIS) and proposes a concrete TKIS scheme.For a TKIS system,at least k out of n helpers are needed to update a user's temporary private key.On the one hand,even if up to k 1 helpers are compromised in addition to the exposure of any of temporary private keys,security of the non-exposed periods is still assured.On the other hand,even if all the n helpers are compromised,we can still ensure the security of all periods as long as none of temporary private keys is exposed.Compared with traditional key-insulated signature(KIS) schemes,the proposed TKIS scheme not only greatly enhances the security of the system,but also provides flexibility and efficiency.展开更多
目的:通过循证医学方法系统评价电针治疗突发性耳聋的临床疗效。方法:系统检索中国知网、万方、维普、Pubmed、Embase、Web of Science、Cochrane Library数据库中自建库至2024年10月7日以来电针治疗突发性耳聋的随机对照试验,由2名研...目的:通过循证医学方法系统评价电针治疗突发性耳聋的临床疗效。方法:系统检索中国知网、万方、维普、Pubmed、Embase、Web of Science、Cochrane Library数据库中自建库至2024年10月7日以来电针治疗突发性耳聋的随机对照试验,由2名研究者参考Cochrane协作网提供的偏倚风险评估工具,采用RevMan 5.3软件进行Meta分析。结果:共纳入8篇文献,样本量为638例,试验组321例,对照组317例。Meta分析结果显示,试验组电针治疗突发性耳聋的总有效率(RR=1.23,95%CI[1.07,1.41],P=0.003)、治愈率(RR=1.73,95%CI[1.28,2.34],P=0.0004)、眩晕总有效率(RR=1.25,95%CI[0.99,1.57],P=0.06)均高于对照组;试验组平均听阈值低于对照组(MD=-6.29,95%CI[-9.01,-3.56],P<0.00001),差异均有统计学意义(P<0.05)。结论:电针治疗突发性耳聋可以提高突发性耳聋总有效率、治愈率、眩晕总有效率,改善平均听阈值。展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 50375130 and 50323003)the Special Foundation for the Authors of National Excellent Doctoral Disserta tions (No. 200234)the Outstanding Young Teachers Program of State Education Ministry (No. 2101)
文摘A so-called 'local probabilistic Paris relation method' was presented for measuring the random thresholds of long fatigue crack propagation. A check was made to the conventional method, in which the thresholds were measured statistically and directly by the test data. It was revealed that this method was not reasonable because the test data have seldom a unified level of crack growth rates. Differently,in the presented method the Paris-Erdogan equation was applied to model the local test data around the thresholds. Local probabilistic relations with both the survival probability and the confidence were established on a lognormal distribution of the stress density factors. And then, the probabilistic thresholds were derived from the probabilistic factors with a given critical level of growth rate. An analysis on the test data of LZ50 axle steel for the Chinese railway vehicles verifies that the present method is feasible and available.
基金Projects(51475462,61174030,61473094,61374126)supported by the National Natural Science Foundation of China
文摘Remaining useful life(RUL) estimation based on condition monitoring data is central to condition based maintenance(CBM). In the current methods about the Wiener process based RUL estimation, the randomness of the failure threshold has not been studied thoroughly. In this work, by using the truncated normal distribution to model random failure threshold(RFT), an analytical and closed-form RUL distribution based on the current observed data was derived considering the posterior distribution of the drift parameter. Then, the Bayesian method was used to update the prior estimation of failure threshold. To solve the uncertainty of the censored in situ data of failure threshold, the expectation maximization(EM) algorithm is used to calculate the posteriori estimation of failure threshold. Numerical examples show that considering the randomness of the failure threshold and updating the prior information of RFT could improve the accuracy of real time RUL estimation.
基金supported by the National Natural Science Foundation of China(61703410,61873175,62073336,61873273,61773386,61922-089)the Basic Research Plan of Shaanxi Natural Science Foundation of China(2022JM-376).
文摘Remaining useful life(RUL)prediction is one of the most crucial components in prognostics and health management(PHM)of aero-engines.This paper proposes an RUL prediction method of aero-engines considering the randomness of failure threshold.Firstly,a random-coefficient regression(RCR)model is used to model the degradation process of aeroengines.Then,the RUL distribution based on fixed failure threshold is derived.The prior parameters of the degradation model are calculated by a two-step maximum likelihood estimation(MLE)method and the random coefficient is updated in real time under the Bayesian framework.The failure threshold in this paper is defined by the actual degradation process of aeroengines.After that,a expectation maximization(EM)algorithm is proposed to estimate the underlying failure threshold of aeroengines.In addition,the conditional probability is used to satisfy the limitation of failure threshold.Then,based on above results,an analytical expression of RUL distribution of aero-engines based on the RCR model considering random failure threshold(RFT)is derived in a closed-form.Finally,a case study of turbofan engine is used to demonstrate the effectiveness and superiority of the RUL prediction method and the parameters estimation method of failure threshold proposed.
基金Supported by the Natural Science Foundation of Hebei Province under Grant No C2013202192
文摘Species evolution is essentially a random process of interaction between biological populations and their environ- ments. As a result, some physical parameters in evolution models are subject to statistical fluctuations. In this work, two important parameters in the Eigen model, the fitness and mutation rate, are treated as Gaassian dis- tributed random variables simultaneously to examine the property of the error threshold. Numerical simulation results show that the error threshold in the fully random model appears as a crossover region instead of a phase transition point, and ＆s the fluctuation strength increases the crossover region becomes smoother and smoother. Furthermore, it is shown that the randomization of the mutation rate plays a dominant role in changing the error threshold in the fully random model, which is consistent with the existing experimental data. The implication of the threshold change due to the randomization for antiviral strategies is discussed.
文摘This research paper proposes a filter to remove Random Valued Impulse Noise (RVIN) based on Global Threshold Vector Outlyingness Ratio (GTVOR) that is applicable for real time image processing. This filter works with the algorithm that breaks the images into various decomposition levels using Discrete Wavelet Transform (DWT) and searches for the noisy pixels using the outlyingness of the pixel. This algorithm has the capability of differentiating high frequency pixels and the “noisy pixel” using the threshold as well as window adjustments. The damage and the loss of information are prevented by means of interior mining. This global threshold based algorithm uses different thresholds for different quadrants of DWT and thus helps in recovery of noisy image even if it is 90% affected. Experimental results exhibit that this method outperforms other existing methods for accurate noise detection and removal, at the same time chain of connectivity is not lost.
文摘In this paper surrogate data method of phase-randomized is proposed to identify the random or chaotic nature of the data obtained in dynamic analysis: The calculating results validate the phase-randomized method to be useful as it can increase the extent of accuracy of the results. And the calculating results show that threshold values of the random timeseries and nonlinear chaotic timeseries have marked difference.
基金the Special Research Fund for the National Natural Science Foundation of China(No.11272082)the Fundamental Research Funds for the Central Universities(No.E022050205)the Open Research Fund of Key Laboratory of Fluid and Power Machinery of Xihua University(No.szjj2013-03)
文摘A method for reliability analysis of the competing failure with the probabilistic failure threshold value not the fixed threshold value is presented, which involves the random shocks and the degradation is independent and dependent respectively. Specifically, for the dependent condition, the effect due to the random shocks on the degradation is considered with a damage factor. In addition, the dependent competing failure model is applied to the reliability analysis of the k-out-of-n systems. Finally, two studied cases are presented to illustrate the proposed method, and the results show the proposed method is reasonable.
基金Project supported by the Doctoral Science Research Start-up Funding of Guizhou Normal University,China(Grant No.11904-0514162)the National Natural Science Foundation of China(Grant No.11474021)
文摘This work demonstrates the realization of a lasing in scattering media,which contains dispersive solution of Zn O nanoparticles（NPs） and laser dye 4-dicyanomethylene-2-methyle-6-（p-dimethylaminostyryl）-4H-pyran（DCM） in negative liquid crystals（LCs） that was injected into a cell.The lasing intensity of the dye-doped negative LC laser can be tuned from low to high if the NPs concentration is increased.The tunability of the laser is attributable to the clusters-sensitive feature in effective refractive index of the negative LCs.Such a tunable negative liquid crystal laser can be used in the fabrication of new optical sources,optical communication,and liquid crystal laser displays.
基金the National Natural Science Foundation of China (Nos.60970111,60903189 and 60903020)the National High Technology Research and Development Program (863) of China (No.2009AA01Z418)the National Basic Research Program (973) of China(No.2007CB311201)
文摘To tackle the key-exposure problem in signature settings,this paper introduces a new cryptographic primitive named threshold key-insulated signature(TKIS) and proposes a concrete TKIS scheme.For a TKIS system,at least k out of n helpers are needed to update a user's temporary private key.On the one hand,even if up to k 1 helpers are compromised in addition to the exposure of any of temporary private keys,security of the non-exposed periods is still assured.On the other hand,even if all the n helpers are compromised,we can still ensure the security of all periods as long as none of temporary private keys is exposed.Compared with traditional key-insulated signature(KIS) schemes,the proposed TKIS scheme not only greatly enhances the security of the system,but also provides flexibility and efficiency.
文摘目的:通过循证医学方法系统评价电针治疗突发性耳聋的临床疗效。方法:系统检索中国知网、万方、维普、Pubmed、Embase、Web of Science、Cochrane Library数据库中自建库至2024年10月7日以来电针治疗突发性耳聋的随机对照试验,由2名研究者参考Cochrane协作网提供的偏倚风险评估工具,采用RevMan 5.3软件进行Meta分析。结果:共纳入8篇文献,样本量为638例,试验组321例,对照组317例。Meta分析结果显示,试验组电针治疗突发性耳聋的总有效率(RR=1.23,95%CI[1.07,1.41],P=0.003)、治愈率(RR=1.73,95%CI[1.28,2.34],P=0.0004)、眩晕总有效率(RR=1.25,95%CI[0.99,1.57],P=0.06)均高于对照组;试验组平均听阈值低于对照组(MD=-6.29,95%CI[-9.01,-3.56],P<0.00001),差异均有统计学意义(P<0.05)。结论:电针治疗突发性耳聋可以提高突发性耳聋总有效率、治愈率、眩晕总有效率,改善平均听阈值。
