An Optimal Production Control Policy for an Unreliable Machine System with Buffer
نویسندگان
چکیده
The paper is to present a simulation method to search for an optimal (z, Z) (z < Z) values for the (z, Z) production control policy so that the expected inventory cost rate (i.e. expected total cost due to both inventory holding and backlog per unit time) is minimal for a single machine system with buffer. The system is subject to operationdependent failure only and alternates between normal and failure. An algorithm is presented to illustrate how to estimate the inventory cost rates for various pairs of (z, Z) and how to get the minimal one among them. Notations C holding cost per unit time for a single product C shortage cost per unit time for a single product d demand rate (constant) γ maximum machine production rate u(t) machine production rate at t J(t) the inventory level of the system at t ,... , 2 1 X X i.i.d. Up times of the machine ,... , 2 1 Y Y i.i.d. Down (i.e repair) time of the machine λ the reciprocal of mean up time, i.e. λ =1/MTTF μ the reciprocal of mean down time, i.e. μ =1/MTTR (z, Z) inventory lower and upper control levels for the (z, Z) production control policy
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