In the vast literature (see among others Bhattacharjee et al., 2013; Iwińska and Szymkowiak, in press; Jiang et al., 2003;
Nanda et al., 2007; Szymkowiak and Iwińska, in preparation) failure rate and aging intensity properties are analyzed for
characterization of nonnegative continuous random variables. In the reliability theory these continuous variables are mainly
used to describe the elements and systems life