A serial finite unreliable queue model for production lines

Serial production lines in practice behave as queuing networks of the tandem type with finite queue length and unreliable servers. The authors present a model for such a system utilizing simulation and analysis. Exponential service times are approximated by sums of deterministic variables using a simple probabilistic technique. The model observes a limited number of events which are sufficient to determine system performance and mean buffer levels. By appropriately reducing the rates of starved and blocked machines and using analysis to compute the times of next event at each machine and buffer, piece-by-piece computations are avoided. It turns out that this approximate model is highly accurate and faster by a factor of 3 or more when compared to conventional piece-by-piece simulators