Research On System Safety Theory Based On Variable Fuzzy Sets

In this paper, the variable fuzzy sets theory is applied to the research on system safety theory which includes assessment, forecasting, decision-making and reliability assessment. Based on variable fuzzy sets theory to solve system safety problem, a whole set model and method system are presented.(1) Based on the analysis of the existing safety assessment method, aiming at the shortcomings and deficiencies of these methods, the variable fuzzy recognition assessment method and the variable fuzzy assessment method of system safety assessment are presented. By comparing the results of these research cases with the method of literature, its superiority and effectiveness are proved.(2) The essence of variable fuzzy comprehensive assessment method is multi-model combination assessment. However, the assessment method doesn’t take the effect of model weight for assessment result into account. Therefore, the weight of models is calculated by improved two element contrasting method base on fuzzy entropy for single sample, the weight of models is calculated by entropy weight method for multiple samples, a group new weighted variable fuzzy assessment method is presented, including the weighted variable fuzzy assessment method for single sample, the weighted variable fuzzy assessment method for multiple samples and the weighted multi-hierarchy variable fuzzy assessment method.The method makes the process of assessment more objective and reasonable.(3) Based on the intrinsic relationship between the variable fuzzy cluster model and the variable fuzzy pattern recognition model, the variable fuzzy combination forecast model of system safety forecast is founded and a method of variable fuzzy combination interval forecast is presented. The variation of weight parameter of variable fuzzy combination forecast model is considered. The mine gas emission is forecasted by the four group weight, the stability and reliability of the result are verified and it helps to improve the credibility of the result of the forecasting. This paper also integrates the example of mine gas emission rate to prove the feasibility and effectiveness of the method. A new way is provided for the mine gas emission rate forecast.(4) This paper analyzes the problems that exist in the process of the application of the two element contrasting method. Based on the advantage of grey correlation analysis method that can objectively determine important order of indexes, two element contrasting method and grey correlation analysis method are combined, and a more objective and reasonable the comprehensive weight method is presented.(5) The scheme optimization is the core of the system safety decision-making. The shortcomings that present scheme optimization method are analyzed. In order to ensure the accuracy and consistency of the optimization results, the variable fuzzy optimization model is founded and the variable fuzzy optimization method of system safety decision-making is presented. One characteristic of the model is that it can heighten the reliability of decision-making system by variability of model. Finally, it gives exemplification analysis of the emergency command decision-making and the safety investment decision-making.(6) The system reliability is inseparable with the system safety. The reliability problem is a matter of success or failure of the system. In order to ensure the safe operation of the system, the prime problem is to make sure the reliability of study means. Therefore, based on the character of system reliability, variable fuzzy assessment model of system reliability comprehensive assessment is founded, variable fuzzy method of system reliability assessment is presented, and the variation of parameter is studied in this model. Finally, by using the example of the reliability assessment of the electric distribution system, the stability and reliability of the method is proved.