“…Transient (time-dependent, non-stationary) results for queueing systems with multiple (repeated) vacation policy, used as a model of energy saving mechanisms, can be found in [18,19,20,21] (compare also [22,23,24]). In particular, in [18,21] the departure process is investigated in cases of infinite and finite buffer capacities, respectively, while in [19] the queueing delay is investigated (also for the single vacation policy). Similarly, transient analysis of power saving models based on the N -policy can be found in [25] (queueing delay) and [26] (departure process).…”