Optimum phase shifting on inventory-production system to reduce cost and to keep the system stable

Sometimes is not possible to dispose enough area to store raw materials and finished products on a shared area. In order to reduce costs in this restricted area, it must apply phase shifting between start production and raw material arrival but not any quantity of phase shifting if system stability is required. Considering inventory-production system as a closed loop system controlled by phase, this paper demonstrate that phase shifting allowed is obtained through applying the phase locked loop (PLL) of telecommunication theory as an alternative to analytical (maximum-minimum) with restrictions method.