  The problem of exact evaluation of the mean service cycle time in tandem
systems of single-server queues with both infinite and finite buffers is
considered. It is assumed that the interarrival and service times of customers
form sequences of independent and identically distributed random variables with
known mean values. We start with tandem queues with infinite buffers, and show
that under the above assumptions, the mean cycle time exists. Furthermore, if
the random variables which represent interarrival and service times have finite
variance, the mean cycle time can be calculated as the maximum out from the
mean values of these variables. Finally, obtained results are extended to
evaluation of the mean cycle time in particular tandem systems with finite
buffers and blocking.

Optimization and Control;Probability