The generalized HNBUE (HNWUE) class of life distributions

This paper examines the properties of a new class of life distributions (and its dual class), named GHNBUE (GHNWUE) whose members have a coefficient of variation less than (greater than) or equal to one. It characterizes the GHNBUE (GHNWUE) property by using the Laplace transform. Several interesting shock models leading to the GHNBUE (GHNWUE) property are studied. These include both homogeneous and nonhomogeneous Poisson processes governing the arrival of shocks. A certain cumulative damage model is also investigated. The paper also examines whether the GHNBUE (GHNWUE) property is preserved under the reliability operations: (i) Convolution, (ii) mixtures and (iii) formation of coherent systems.