  This paper deals with the assessment of the performance of a system under a
finite planning horizon. The system is subject to two dependent causes of
failure: internal degradation and sudden shocks. We assume that internal
degradation follows a gamma process. When the deterioration level of the
degradation process exceeds a predetermined value, a degradation failure
occurs. Sudden shocks arrive at the system following a doubly stochastic
Poisson process (DSPP). A sudden shock provokes the total breakdown of the
system. A condition-based maintenance (CBM) with periodic inspection times is
developed. To evaluate the maintenance cost, recursive methods combining
numerical integration and Monte Carlo simulation are developed to evalute the
expected cost rate and its standard deviation. Also, recursive methods to
calculate some transient measures of the system are given. Numerical examples
are provided to illustrate the analytical results.
