The upperbound of the restoration function in the case of instantancous replacement by «aging» elements

A failed core element of a system is instantaneously replaced by a spare one whichbecomes a core element. Spare elements may partly lose their reliability resource, or «age», in storage. The time when the system starts functioning does not necessarily coincide with that when spare elements are manufactured. The upperbounds are found of the restoration function with the element reliability resource distribution assumed to belong to the range of distributions whose intensity function grows.