在生產管理領域中，要同時決定最小化存貨水準及滿足顧客需求是現今企業經常面臨到的困境，由此可知存貨管理是一門相當重要的議題。
本研究利用Arena建立一個具有服務水準限制式下的兩階層存貨模擬模型，並以最小化總存貨成本為目標，利用OptQuest求得最佳的再訂購點和訂購量。本研究模型，包含三間零售商和一間總倉，各倉庫皆遵從連續的(R,Q)政策。
由結果顯示, 本研究所提出的方法可以有效的解決隨機性的存貨問題，並且與傳統的數學方法不同的是，不需要進行龐大的計算及複雜的供應鏈系統分析，就可以找到最佳的決策變數。有鑒於此，本研究建議結合Arena和OptQuest解決具有隨機性之存貨問題。

Inventory management is an important issue, because it is very difficult to decide whether minimizing the level of inventory or satisfying customer demand is more important, and thus companies face a dilemma in this regard.
In this Master’s Thesis, we present a simulation model for the two-echelon inventory optimization problem using Arena and OptQuest subject to service level constraints, with the objective being to minimize the total inventory cost when the decision variables are the reorder point and reorder quantity. In the example examined in this work, there are three retailers; and one warehouse, with each adopting a continuous inventory control review (R,Q) policy.
The results show that the proposed method is very capable of solving stochastic problems, and that it can find the best combination of our decision variables without the hundreds, or even thousands of calculations that traditional mathematical approaches need to analyze complex supply chain systems. We thus recommend using Arena with OptQuest to solve such complex problems.

Al-Rifai, M.H. and Rossetti, M.D., 2007. An efficient heuristic optimization algorithm for a two-echelon (R, Q) inventory system. International Journal of Production Economics, 109(1-2), 195–213.
Anon, 2008. Proceedings of the 2008 Winter Simulation Conference S. J. Mason, R. R. Hill, L. Mönch, O. Rose, T. Jefferson, J. W. Fowler eds. , 2632–2638.
April, J. and Glover, F., 2003. Practical introduction to simulation optimization. Proceedings of the Winter Simulation Conference.
Axsäter, S., 1998. EVALUATION OF INSTALLATION STOCK BASED ( R , Q ) -POLICIES FOR TWO-LEVEL INVENTORY SYSTEMS WITH POISSON DEMAND. , 46(3).
Axsäter, S., 2000. Exact analysis of continuous review (R, Q) policies in two-echelon inventory systems with compound Poisson demand. Operations Research, 48(5), 686–696.
Axsäter, S., 1993. Exact and approximate evaluation of batch-ordering policies for two-level inventory systems. Operations research, 41(4), 777–785.
Axsäter, S., 1997. Simple evaluation of echelon stock (R, Q) policies for two-level inventory systems. IIE transactions, 37–41.
Axsäter, S., 1990. SIMPLE SOLUTION PROCEDURES FOR A CLASS PROBLEMS INVENTORY OF TWO-ECHELON. , 38(1), 64–69.
Axsäter, S., Forsberg, R. and Zhang, W., 1994. Approximating general multi-echelon inventory systems by Poisson models. International Journal of Production …, 35, 201–206.
Banks, J., Carson, J.S., Nelson, B.L. and Nicol, D.M., 2005. Discrete-Event System Simulation Internatio., Hall, Prentice.
Bramel, J. and Simchi-Levi, D., 1997. The Logic of Logistics, Springer Berlin Heidelberg.
Chen, F., 1997. One-Warehouse Multiretailer Systems with Centralized Stock Information. Operations Research, 45(2), 275–287.
Chew, E.P. and Tang, L.C., 1995. Warehouse-retailer system with stochastic demands - Non-identical retailer case. , 2217(93).
Christopher, M., 2005. Logistic and Supply Chain Management, Prentice Hall.
Diaz, A., 2003. Modelling approaches to optimise spares in multi-echelon systems. International Journal of Logistics, (October 2012), 37–41.
Diks, E.B. and De Kok, a. G., 1999. Computational results for the control of a divergent N-echelon inventory system. International Journal of Production Economics, 59(1-3), 327–336.
Diks, E.B., De Kok, a. G. and Lagodimos, a. G., 1996. Multi-echelon systems: A service measure perspective. European Journal of Operational Research, 95(2), 241–263.
Dong, M. and Frank Chen, F., 2005. Performance modeling and analysis of integrated logistic chains: An analytic framework. European Journal of Operational Research, 162(1), 83–98.
Fu, M., 2002a. Optimization for simulation: Theory vs. practice. INFORMS Journal on Computing.
Fu, M., 2002b. Optimization for simulation: Theory vs. practice. INFORMS Journal on Computing, 14(30), pp.192–215.
Glasserman, P. and Tayur, S., 2012. Sensitivity Analysis for Levels in Multiechelon Production-inventory Systems. , 41(2), 263–281.
Glover, F. and Kelly, J.P., 1999. NEW ADVANCES FOR WEDDING OPTIMIZATION AND SIMULATION.
Harrington, H.J. and Kerim Tumay, 2000. Simulation Modeling Methods, McGraw-Hill Education (India) Pvt Limited.
Inderfurth, K. and Minner, S., 1998. Safety stocks in multi-stage inventory systems under different service measures. European Journal of Operational Research, 106(1), 57–73.
Kleijnen, J.P.C. and Wan, J., 2007. Optimization of simulated systems: OptQuest and alternatives. Simulation Modelling Practice and Theory, 15(3), 354–362.
Lagodimos, A.G., 1992. Multi-echelon service models for inventory systems under different rationing policies. International Journal of Production Research, 30, 939–958.
Laguna, M., 2011. OptQuest Optimization of Complex Systems.
Laguna, M. and Martí, R., 2002. OptQuest callable libraries. In V. Stefan and W. D. L., eds. Optimization Software Class Libraries. Boston: Kluwer Academic Publishers, pp. 193–218.
Mak, H. and Shen, Z.M., 2009. A Two-Echelon Inventory-Location Problem with Service Considerations.
Minner, S., 2000. Strategic Safety Stocks in Supply Chains, Springer Berlin Heidelberg.
Moinzadeh, K. and Lee, H., 1986. Batch size and stocking levels in multi-echelon repairable systems. Management Science, 32(12), 1567–1581.
Nahmias, S. and Smith, S.A., 1994. Optimizing Inventory Levels in a Two-Echelon Retailer System with Partial Lost Sales. Management Science, 40(5), 582–596.
Paschalidis, I.C., Liu, Y., Cassandras, C.G. and Panayiotou, C., 2004. Inventory Control for Supply Chains with Service Level Constraints: A Synergy between Large Deviations and Perturbation Analysis. Annals of Operations Research, 126, 231–258.
Paul H. Zipkin, 2000. Foundations of Inventory Management, McGraw-Hill.
Rau, H., Wu, M.-Y. and Wee, H.-M., 2003. Integrated inventory model for deteriorating items under a multi-echelon supply chain environment. International Journal of Production Economics, 86(2), 155–168.
Rogers, P., 2002. Optimum-seeking simulation in the design and control of manufacturing systems: Experience with optquest for arena. Proceeding Winter Simulation 2002, 1142–1150.
Seifbarghy, M. and Jokar, M.R.A., 2006. Cost evaluation of a two-echelon inventory system with lost sales and approximately Poisson demand. International Journal of Production Economics, 102(2), 244–254.
Strack, G. and Pochet, Y., 2010. An integrated model for warehouse and inventory planning. European Journal of Operational Research, 204(1), 35–50.
Tee, Y. and Rossetti, M.D., 2001. USING SIMULATION TO EVALUATE A CONTINUOUS REVIEW ( R , Q ) TWO-ECHELON INVENTORY MODEL.
Tee, Y.-S. and Rossetti, M.D., 2002. A robustness study of a multi-echelon inventory model via simulation. International Journal of Production Economics, 80(3), 265–277.