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1,131 results on '"Li, Yan-Feng"'

154. A Novel Reliability Analysis Method for Turbine Discs with the Mixture of Fuzzy and Probability-Box Variables.

Author

Zhang, Xiaoqiang, Gao, Huiying, Li, Yan-Feng, and Huang, Hong-Zhong

Subjects
MONTE Carlo method, SADDLEPOINT approximations, TURBINES, GAUSSIAN mixture models, RANDOM variables, AEROSPACE engineers
Abstract

Fuzzy and probability-box (p-box) variables exit widely in aerospace engineering. To evaluate the reliability of turbine discs under the mixture of these two types of variables and guarantee safety, the critical point lies in how to deal with the fuzzy variables. In this paper, a novel method based on equivalent transformation of entropy and saddlepoint approximation (SPA) is proposed to estimate the reliability of turbine discs with the mixture of fuzzy and p-box variables. The advantage of the proposed method is that it can transform fuzzy variables whose memberships are non-normal into normal random variables through entropy invariability; meanwhile, using the SPA, the required sample size and corresponding computational cost decreases greatly. An example is used to illustrate the proposed method and a comparison is also made with the interval Monte Carlo simulation (IMCS). The results indicate that the proposed method is promising and has higher efficiency with almost the same accuracy. [ABSTRACT FROM AUTHOR]

Published
2022
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155. Bayesian prior information fusion for power law process via evidence theory.

Author

Hu, Jun-Ming, Huang, Hong-Zhong, Li, Yan-Feng, and Gao, Hui-Ying

Subjects
COMPUTER performance, PROBABILITY density function, CHANNEL estimation, PARAMETER estimation, BAYES' estimation, RELIABILITY in engineering
Abstract

The power law process (PLP) is widely used to analyze the failures of repairable systems, and the PLP parameter estimation is the primary concern for reliability assessment or maintenance decision making. Although the Bayesian estimation of the PLP has been studied in existing research, little attention has been paid to how to obtain its prior distribution, especially when the prior information is coming from multiple sources. To address this problem, a framework for Bayesian prior information fusion using evidence theory is proposed in this paper. This framework first uses evidence theory to represent the prior information from multiple sources or experts and then combines them into fused information. Based on the belief and plausibility functions of the fused information, the prior distribution is bounded by an upper and lower probability density functions which are derived by moment equivalence. A case study is also carried out to verify and illustrate the proposed method. The results show that this proposed approach is beneficial for the Bayesian estimation of the power law process. [ABSTRACT FROM AUTHOR]

Published
2022
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172. Influencing factors and isothermal kinetics of fluorapatite reduction

Author

Li Yan-Feng, Han Yue-Xin, Sun Yong-Sheng, Wang Ding-Zheng, Li Yan-Feng, Han Yue-Xin, Sun Yong-Sheng, and Wang Ding-Zheng

Abstract

The effects of reduction time, reduction temperature and content of silica, iron oxide or carbon on the reduction of fluorapatite, in the process of coal-based reduction of high-phosphorus iron, were studied by mixing pure minerals in an experiment. On this basis, the reduction kinetic mechanism function and isothermal kinetic equation of fluorapatite in Ca10(PO4)6F2-SiO2-Fe2O3-C system were investigated. The results show that increasing the amounts of silica, iron oxide and carbon, and decreasing time and temperature, can accelerate the reduction reactions of fluorapatite under experimental conditions. In Ca10(PO4)6F2-SiO2-Fe2O3-C system, the optimum ratios of silica and iron oxide compared to fluorapatite are 1.8 and 2.2, respectively, and the optimal C/O molar ratio is 2.0. Based on the optimal amount of reactants, the best mechanism function for the reduction of fluorapatite is the A1/3: 1/3(1-alpha)[-ln(1-alpha)]-2; the best kinetic equation is K(T)=3.89033×107exp(-282.748×103/RT), where the pre-exponential factor is 3.89033×107 min-1, and the activation energy is 282.748 kJ/mol. The limiting factor of the reduction reaction is solid-state diffusion., The effects of reduction time, reduction temperature and content of silica, iron oxide or carbon on the reduction of fluorapatite, in the process of coal-based reduction of high-phosphorus iron, were studied by mixing pure minerals in an experiment. On this basis, the reduction kinetic mechanism function and isothermal kinetic equation of fluorapatite in Ca10(PO4)6F2-SiO2-Fe2O3-C system were investigated. The results show that increasing the amounts of silica, iron oxide and carbon, and decreasing time and temperature, can accelerate the reduction reactions of fluorapatite under experimental conditions. In Ca10(PO4)6F2-SiO2-Fe2O3-C system, the optimum ratios of silica and iron oxide compared to fluorapatite are 1.8 and 2.2, respectively, and the optimal C/O molar ratio is 2.0. Based on the optimal amount of reactants, the best mechanism function for the reduction of fluorapatite is the A1/3: 1/3(1-alpha)[-ln(1-alpha)]-2; the best kinetic equation is K(T)=3.89033×107exp(-282.748×103/RT), where the pre-exponential factor is 3.89033×107 min-1, and the activation energy is 282.748 kJ/mol. The limiting factor of the reduction reaction is solid-state diffusion.

Published
2020

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