Estimating the productivity of materials handling systems is an important task, which has to be realized in various logistics, industrial, and transportation systems.
Productivity calculation may be done in several ways. Usual techniques are simple a...
Estimating the productivity of materials handling systems is an important task, which has to be realized in various logistics, industrial, and transportation systems.
Productivity calculation may be done in several ways. Usual techniques are simple analytical techniques based on cycle time calculation in case of cyclic handling facilities (cranes, lift trucks, trailers,…). Also, very often simulation and queuing theory is also used. However, as a rule, all those approaches, except simulation, are usually used for productivity calculation for the case of single stage material handling systems. On the other hand, many material handling processes in real systems are multi-stage in nature (the best example is container port where loading-unloading processes are realized successively by berth cranes, trailers and yard cranes). Thus an analytic technique, accurate enough, undoubtedly could be always useful.
In this paper an analytical approach is considered. The analytic model is based on probability theory and gives opportunity for very accurate calculation of compound (composite) cycle time of three-stage materials handling system in case when the probability distribution of “technical” cycle times of each stage is known.