極値解析の実プラント腐食問題への適用におけるパラメータ推定法による差異

Abstract

The parameters of extreme value statistical analysis are calculated by several methods, for example, the method of least squares (MLS), minimum variance linear unbiased estimator method (MVLUE), and maximum likelihood estimator method (MLE). We have examined difference in value of the parameters estimated by the above three methods and compared the calculated maximum value with the actual value of corrosion rate for several cases in chemical process plants.In conclusion, MVLUE was the best method for estimating the maximum value of corrosion rate independent of kind of machines, atmosphere, types of corrosion and corrosion positions. The following relation was observed in the estimated values of scale parameter (α), MLS>MVLUE>MLE but no difference in the estimated value of location parameter (λ) was recognised among the above three methods.