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This paper deals with the detection of the catastrophic failure and the detection and prediction of the deteriorative failure by using adaptive digital filter. Assuming that the change of states of system can be measured as the change of statistical characteristics of observed randam signals, the autoregressive(AR) model is fitted to the signals, and the deteriorative performance index is calculated to detect and predict the deteriorative failure continuously in time. The index is computed to measure the statistical difference between normal and other states quantitatively. The three kinds of indices, that is, quadratic distance of AR parameter differencies, variance of the residuals for prediction scheme, and distance of the time series by the Kullback information, are introduced. Furthermore, the present method is able to eliminate the inferior signals contained in the observed signals and to improve the detection and prediction accuracies by an on-line algorithm. Finally, the effectiveness of the present algorithm is shown by numerical simulations.

Hydrogen absorption and desorption properties of UTi and UZr alloys were investigated at hydrogen pressures below 105Pa and temperatures up to 873 K. Under such conditions, some uranium alloys showed as good characteristics as pure uranium and resulted in less degree of powderization after hydrogenation under an atmospheric pressure.