【正文】 cal inventory control systems,and also paring their proposed/improved systems to a classical inventory control system.Yoo et al.(1997) proposed an improved Distribution Resource Planning(DRP)method using concepts of installationstock s,Q and R,S order quantities and order points are dynamically determined to meet the demand in a justintime concept and minimize the outofstock the improved system,regional distribution centers can make a decision to reduce the related costs— order only the amount available or postpone the ordering. Based on experiments,the proposed system out performs he classical relevant research work belongs to De Kok andFransoo(2020).The authors proposed the socalled Synchronized Based Stock(SBS)policy and pared its performance to the LPbased system under the backlogging SBS, which uses the basestockpolicy concept,raises the inventory position to meet the adjustable target level in every inventory is concluded that the SBS outperforms the LPbased system considerably because it uses more sophisticated ordering method and rationing et al.(2020)studied two inventory control systems,namely,DRP and Reorder Point systems in a fourechelon system refers to a calculation of upstream reorder quantities and reorder intervals by aggregating all downstream demands and offsetting them by related lead Reorder Point system refers to a situation that manufacturers forecast needs at the distribution centers.The authors concluded that the DRP system gives higher service levels and lower cycle ti s,S system where s and S vary with states(SMART s,S system)was proposed by Giannoccaro and Pontrandolfo(2020).A threestage serial supply chain is formulated as a semiMarkov decision process model and then solved by SMART(semiMarkov average reward technique) authors pared the SMART s,S system to the echelonstock R,Ssystem and then summarized that the SMART s,S system gives lower total costs and is more robust if demand undergoes only slight et al.(2020)proposed justintimedistribution requirements planning(JITDRP)which aims to pull material through a multiwarehouse/multiretailer supply chain JITDRP gives optimal solutions under deterministic review determining suitable control parameters of classical systems:The classical inventory control system in supply chains can be broadly divided intotwo types,namely, installationstock and echelonstock inventory control difference between them is mainly based on information used to make an inventory replenishment echelonstock inventory control system allows the planner to utilize the work information, while the installationstock control system allows the planner to use only local of the two categories can be seen in Axsa168。0:1。otherwise,nothing is done until the next r retailer inventory position is defined as onhand inventory plus inventory intransit from the warehouse to the warehouse inventory position is the sum of onhand inventory and inventory intransit from a vendor plus all downstream inventories including pipeline all retailer orders cannot be fulfilled by the onhand inventory at warehouse at any period,the available inventory at the warehouse will be rationed so asto maximize the minimum inventory position among all retailers(see Whybark andYang,1996).Unfortunately,an exact method to determine the optimal control parameters of the echelonstock R,s,S control policy for a lostsale model is not known in the good approximate method can be found in Schneider and Rinks(1991)and Schneider et al.(1995).Even though Schneider and Rinks(1991)and Schneideret al.(1995)provide a good approximation for parameter setting for the echelonstock R,s,S control policy,their model is developedbased on the backlogging model and the authors have not guaranteed the adaptation of their model to the lostsale model as studied in this ,in this paper,the method of Schneider and Rinks(1991) and Schneider et al.(1995)is used to determine the initial valuesof the control parameters s and S. Then,simulation experiments are conducted to manipulate the values of s and S until the best ones are obtained— the R value is fixed to one,s and S are manipulated until the required fill rate is obtained while other parameters are kept though there are many sets of s and S which can give the same value of desired fill rate,the one which can give minimum total cost is selected. design This section explains simulation experiments to investigate the effectiveness of the IDPcontrol experiments are divided into three parts as follows: on effects of safety stock factor ki of IDP control system:As discussed in Section4,the safety stock factor ki influences the effectiveness of the IDP control subsection is devoted to investigate the role of ki in terms of safety stock policy[K1,K2].Thevalues of K1 and K2 will be varied and the effects on fill rates and total costs will be analyzed. between the IDP and R,s,S control systems:The effectiveness of the IDP control system is evaluated against the echelonstock R,s,S control best results obtained from both control systems are statistically is noted that when the echelonstock R,s,S control system is used and the supply chain faces nonstationary demand,amethod presented in Appendix A is used to determine the control initial inventory at each node is set equal to the associated orderupto level S. on effects of cost structures of the supply chain:It is possible that the relative magnitude of cost structures of the supply chain may affect the abovementioned erefore,the cost structure is changed by increasing the unit lostsale cost by 20– 100%while other cost parameters(ordering,holding,and transportation costs)are kept constant. and discussions This section contains results of the simulation experiments. of the study on the effects of the safety st