Abstract: The process Xs of interpoint distance between all pairs of points in the random process Zt is constructed. It is proved that Xs could reflect the changes of first- and second-order moment function of Zt. Also it is proved that correlation integral could reflect the unsteadiness of Zt. According to the function of probability density of Xs, the method of taking value of reference distance in correlation integral formula is proposed. Based on correlation integral, the unsteadiness-measuring parameters of equipment dynamical process are defined which are absolute degree of unsteadiness, relative degree of unsteadiness, absolute ratio of unsteadiness and relative ratio of unsteadiness. By means of the applications of these parameters to a real case of production field and a case of our experiment, it is demonstrated that the unsteadiness-measuring parameters are available in equipment-diagnosing engineering. The use of these parameters to the system of signal analysis and fault diagnosis is presented.

Key words: Correlation integral, Process unsteadiness, Ratio of process unsteadiness, Rotate stall, Unsteady signal