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Probability estimation of rare events is a challenging task in the reliability theory. Subset simulation (SS) is a robust simulation technique that transforms a rare event into a sequence of multiple intermediate failure events with large probabilities and efficiently approximates the mentioned probability. Proper handling of a reliability problem by this method requires employing a suitable sampling approach to transmit samples toward the failure set. Markov Chain Monte Carlo (MCMC) is a suitable sampling approach that solves the SS transition phase using the failed sample of each simulation level as the seed of next samples. This paper is aimed to study the seed selection effect on the SS accuracy through several seed selection approaches inspired by the genetic algorithm and particle filter and using the main PDF of the variables to assign a mass function probability to each subset sample in the failure domain. Roulette wheel (I, II), tournament and proportional probability techniques are then employed to choose the weighed samples as seeds to be placed in the MCMC to transmit the samples. To examine the capability of each approach, reliabilities of some engineering problems were investigated and results showed that the proposed approaches could find proper failure sets better than the original SS method, especially in problems with several failure domains.
相似文献CdTe solar cells are investigated using a solar cell capacitance simulator software. First, a conventional fluorine-doped tin oxide (FTO)/i-SnO2/CdS/CdTe structure is simulated using input experimental data to verify the simulation process. To make the cell more economical, the thickness of the CdTe layer is decreased, resulting in a degradation of the device performance. To decrease the minority-carrier recombination loss of the designed structure, a p-type Cu2O layer is exploited at the back contact as a hole transport electron blocking layer (HT–EBL). To address the performance degradation, a ZnS/CdS bilayer is used as the window layer. The interdiffusion of Cd into the ZnS due to annealing treatment and the formation of ZnxCd1?xS compound are also studied. Cell parameters include the thickness, doping concentration, and carrier lifetime are then optimized to enhance the power conversion efficiency (PCE). The proposed FTO/i-SnO2/Zn0.5Cd0.5S/CdTe/Cu2O configuration shows the best PCE of 17.5%, short-circuit current density (Jsc) of 27.8 mA/cm2, open-circuit voltage (Voc) of 0.87 V, and fill factor of 72.34% under AM1.5G illumination.
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