Reliability analysis of repairable k-out-n system from time response under several times stochastic shocks

Fang, Yongfeng,Tao, Wenliang,Tee, Kong Fah Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.14 No.4

The model of unit dynamic reliability of repairable k/n (G) system with unit strength degradation under repeated random shocks has been developed according to the stress-strength interference theory. The unit failure number is obtained based on the unit failure probability which can be computed from the unit dynamic reliability. Then, the transfer probability function of the repairable k/n (G) system is given by its Markov property. Once the transfer probability function has been obtained, the probability density matrix and the steady-state probabilities of the system can be retrieved. Finally, the dynamic reliability of the repairable k/n (G) system is obtained by solving the differential equations. It is illustrated that the proposed method is practicable, feasible and gives reasonable prediction which conforms to the engineering practice.

Analysis of structural dynamic reliability based on the probability density evolution method

Yongfeng Fang,Jianjun Chen,Kong Fah Tee 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.2

A new dynamic reliability analysis of structure under repeated random loads is proposed in this paper. The proposed method is developed based on the idea that the probability density of several times random loads can be derived from the probability density of single-time random load. The reliability prediction models of structure based on time responses under several times random loads with and without strength degradation are obtained by using the stress-strength interference theory and probability density evolution method. The resulting differential equations in the prediction models can be solved by using the forward finite difference method. Then, the probability density functions of strength redundancy of the structures can be obtained. Finally, the structural dynamic reliability can be calculated using integral method. The efficiency of the proposed method is demonstrated numerically through a speed reducer. The results have shown that the proposed method is practicable, feasible and gives reasonably accurate prediction.

Time-variant structural fuzzy reliability analysis under stochastic loads applied several times

Yongfeng Fang,Jianbin Xiong,Kong Fah Tee 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.3

A new structural dynamic fuzzy reliability analysis under stochastic loads which are applied several times is proposed in this paper. The fuzzy reliability prediction models based on time responses with and without strength degeneration are established using the stress-strength interference theory. The random loads are applied several times and fuzzy structural strength is analyzed. The efficiency of the proposed method is demonstrated numerically through an example. The results have shown that the proposed method is practicable, feasible and gives a reasonably accurate prediction. The analysis shows that the probabilistic reliability is a special case of fuzzy reliability and fuzzy reliability of structural strength without degeneration is also a special case of fuzzy reliability with structural strength degeneration.

Reliability analysis of repairable k-out-n system from time response under several times stochastic shocks

Yongfeng Fang,Wenliang Tao,Kong Fah Tee 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.4

The model of unit dynamic reliability of repairable k/n (G) system with unit strengthdegradation under repeated random shocks has been developed according to the stress-strength interferencetheory. The unit failure number is obtained based on the unit failure probability which can be computed fromthe unit dynamic reliability. Then, the transfer probability function of the repairable k/n (G) system is givenby its Markov property. Once the transfer probability function has been obtained, the probability densitymatrix and the steady-state probabilities of the system can be retrieved. Finally, the dynamic reliability of therepairable k/n (G) system is obtained by solving the differential equations. It is illustrated that the proposedmethod is practicable, feasible and gives reasonable prediction which conforms to the engineering practice.

Analysis of structural dynamic reliability based on the probability density evolution method

Fang, Yongfeng,Chen, Jianjun,Tee, Kong Fah Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.2

A new dynamic reliability analysis of structure under repeated random loads is proposed in this paper. The proposed method is developed based on the idea that the probability density of several times random loads can be derived from the probability density of single-time random load. The reliability prediction models of structure based on time responses under several times random loads with and without strength degradation are obtained by using the stress-strength interference theory and probability density evolution method. The resulting differential equations in the prediction models can be solved by using the forward finite difference method. Then, the probability density functions of strength redundancy of the structures can be obtained. Finally, the structural dynamic reliability can be calculated using integral method. The efficiency of the proposed method is demonstrated numerically through a speed reducer. The results have shown that the proposed method is practicable, feasible and gives reasonably accurate prediction.

Structural reliability analysis using response surface method with improved genetic algorithm

Yongfeng Fang,Kong Fah Tee 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.62 No.2

For the conventional computational methods for structural reliability analysis, the common limitations are long computational time, large number of iteration and low accuracy. Thus, a new novel method for structural reliability analysis has been proposed in this paper based on response surface method incorporated with an improved genetic algorithm. The genetic algorithm is first improved from the conventional genetic algorithm. Then, it is used to produce the response surface and the structural reliability is finally computed using the proposed method. The proposed method can be used to compute structural reliability easily whether the limit state function is explicit or implicit. It has been verified by two practical engineering cases that the algorithm is simple, robust, high accuracy and fast computation.

Repairable k-out-n system work model analysis from time response

Yongfeng Fang,Webliang Tao,Kong Fah Tee 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.6

A novel reliability-based work model of k/n (G) system has been developed. Unit failure probability is given based on the load and strength distributions and according to the stress-strength interference theory. Then a dynamic reliability prediction model of repairable k/n (G) system is established using probabilistic differential equations. The resulting differential equations are solved and the value of k can be determined precisely. The number of work unit k in repairable k/n (G) system is obtained precisely. The reliability of whole life cycle of repairable k/n (G) system can be predicted and guaranteed in the design period. Finally, it is illustrated that the proposed model is feasible and gives reasonable prediction.

Current utilization of waste biomass as filler for wood adhesives: A review

Jinming Liu,Yongfeng Li,Hailin Mo,Enjun Xie,Jianlin Fang,Weixing Gan 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-

Filler is one of the most important additives for wood adhesives. The introduction of filler offers variousfunctions for wood adhesives, such as the increase of initial viscosity, the decrease of permeability, theimprovement of bonding strength, and the reduction of production cost. However, flour, a grain resource,is widely used as a filler that is added to polymers in the production of wood-based panels. As a result, alarge number of edible resources are wasted every year. Waste biomass that biomass residues are abandonedin nature are a promising filler that can be used to replace flour. The utilization of waste biomass asfiller for wood adhesives to prepare wood-based panels not only improves its mechanical strength, butalso reduces formaldehyde emissions. However, most waste biomass shows disappointing prepressingproperties. Advances in the use of waste biomass as an alternative filler for wood adhesives werereviewed. In addition, the current limitations and future prospects of waste biomass were discussed. Recycling waste biomass is a useful way to avoid the enormous amount of waste generated by differentindustries and control environmental pollution. It contributes to the practical development of circulareconomy.

Geochronological and geochemical constraints on petrogenesis of the Hongyuan intrusion in central West Junggar, Xinjiang, NW China

Shaoni Wei,Fang An,Yongfeng Zhu,Lei Zhao 한국지질과학협의회 2023 Geosciences Journal Vol.27 No.4

Late Paleozoic intermediate–acidic intrusions, which are widespread in central West Junggar (NW China), provide critical information for regional tectonic evolution. The Hongyuan intrusion, distributed in the southeast of central West Junggar, is selected as a representative for discussion in this study. Petrological observation shows that the Hongyuan intrusion is dominated by syenogranite and monzonitic granite, with a small amount of quartz syenite. Zircons separated from the monzonitic granite yield a weighted mean 206Pb/238U age of 287 ± 2 Ma (n = 19, MSWD= 1.3). The Hongyuan intrusion displays a pronounced I-type affinity. It belongs to high-K calc-alkaline suit and has high concentrations of Na2O + K2O (7.00–8.09 wt%). It is peraluminous in composition and the FeOT/MgO ratios are low (2.55–4.43). The large ion lithophile elements (LILE, such as Th, U and Cs) and light rare earth elements (LREE) are enriched with significant Eu anomalies (EuN/EuN* = 0.26–0.51), and the high field strength elements (HFSE, such as Ti and Nb) are depleted. Initial Hf isotopic ratio of zircons separated from the monzonitic granite show small range of variation ((176Hf/177Hf)i = 0.282951–0.283025), the εHf(t) values are relatively high (+12.8 to +15.3) and the Hf model ages are very young (TDM1 = 315–425Ma). The comprehensive petrological and geochemical features indicate that the Hongyuan intrusion was formed by decompression melting of a juvenile lower crust, and has undergone a remarkable process of fractional crystallization.

Ultrathin Trilayer Assemblies as Long-Lived Barriers against Water and Ion Penetration in Flexible Bioelectronic Systems

Song, Enming,Li, Rui,Jin, Xin,Du, Haina,Huang, Yuming,Zhang, Jize,Xia, Yu,Fang, Hui,Lee, Yoon Kyeung,Yu, Ki Jun,Chang, Jan-Kai,Mei, Yongfeng,Alam, Muhammad A.,Huang, Yonggang,Rogers, John A. American Chemical Society 2018 ACS NANO Vol.12 No.10

<P>Biomedical implants that incorporate active electronics and offer the ability to operate in a safe, stable fashion for long periods of time must incorporate defect-free layers as barriers to biofluid penetration. This paper reports an engineered material approach to this challenge that combines ultrathin, physically transferred films of silicon dioxide (t-SiO<SUB>2</SUB>) thermally grown on silicon wafers, with layers of hafnium oxide (HfO<SUB>2</SUB>) formed by atomic layer deposition and coatings of parylene (Parylene C) created by chemical vapor deposition, as a dual-sided encapsulation structure for flexible bioelectronic systems. Accelerated aging tests on passive/active components in platforms that incorporate active, silicon-based transistors suggest that this trilayer construct can serve as a robust, long-lived, defect-free barrier to phosphate-buffered saline (PBS) solution at a physiological pH of 7.4. Reactive diffusion modeling and systematic immersion experiments highlight fundamental aspects of water diffusion and hydrolysis behaviors, with results that suggest lifetimes of many decades at physiological conditions. A combination of ion-diffusion tests under continuous electrical bias, measurements of elemental concentration profiles, and temperature-dependent simulations reveals that this encapsulation strategy can also block transport of ions that would otherwise degrade the performance of the underlying electronics. These findings suggest broad utility of this trilayer assembly as a reliable encapsulation strategy for the most demanding applications in chronic biomedical implants and high-performance flexible bioelectronic systems.</P> [FIG OMISSION]</BR>