Properties of aging intensity function

Recently, the concept of aging intensity (AI) function has been introduced in the literature for evaluating the aging property of a unit (that may be a system or a living organism) quantitatively. In this paper, we discuss the properties of AI function and study its nature for various distributions. The closure properties of the aging classes defined in terms of AI function are also presented. We define an ordering, called aging intensity ordering, and study its closure properties under different reliability operations, viz., formation of k-out-of-n system, and increasing transformations.