Hardware Reliability Analysis of a Coal Mine Gas Monitoring System Based on Fuzzy-FTA

The hardware reliability of a gas monitoring system was investigated using the fuzzy fault tree analysis method. A fault tree was developed considering the hardware failure of the gas monitoring system as a top event. Two minimum path sets were achieved through qualitative analysis using the ascending method. The concept of fuzzy number of the fuzzy set theory was applied to describe the probability of basic event occurrence in the fault tree, and the fuzzy failure probabilities of the middle and top events were calculated using fuzzy AND and OR operators. The results show that the proposed fuzzy fault tree is an effective method of reliability analysis for gas monitoring systems. Results of calculations using this method are more reasonable than those obtained with the conventional fault tree method.

Fuzzy Fault Tree Reliability Analysis Based on Improved T–S Model with Application to NC Turret

In Takagi and Sugeno (T–S) fuzzy fault tree analysis (FFTA), the construction of T-S fuzzy gates relies too much on expert experience, which will result in inevitable subjective errors. In order to overcome this disadvantage, a new method was proposed which combined importance index with T-S fuzzy fault tree model to evaluate reliability of the events. The importance index of components can be solved through Monte Carlo (MC) simulation. The proposed method is suitable for systems where exact information on the fault probabilities of the components and the magnitude of failure and effect on system are not available. The concept and calculation method of T-S probability importance was presented. Finally, the feasibility of the method is verified by analyzing the reliability of the sealing subsystem of the NC turret and the weak links of the system are obtained by the importance analysis, which will provide data for system fault diagnosis and preventive maintenance.