مديريت موجودي در يك سيستم زنجيره‌ي تامين حلقه‌بسته‌ي سه‌سطحي با بازگشتيها و تقاضاي همبسته

Inventory Management in a Three-Echelon Closed-Loop Supply Chain with Correlated Demands and Returns

اين نوشتار به بررسي مسيله‌ي مديريت موجودي در يك زنجيره‌ي تامين حلقه‌بسته، و نيز بسط و توسعه‌ي مدلهاي قطعي و تصادفي براي يك سيستم سه‌سطحي زنجيره‌ي تامين با تقاضا و بازگشتي همبسته اختصاص دارد. بدين‌منظور، هزينهها از ديدگاه سيستم موجودي در نظر گرفته شده، و سيستم بازنگري موجودي در هر دو صورت مرور دايم و مرور دوره‌يي تحت حالتهاي فروش از دست رفته و تخصيص مورد بررسي قرار ميگيرد. سپس با استفاده از جعبه‌ابزار الگوريتم ژنتيك در نرم‌افزار مطلب به حل مدل پرداخته و اثر تغيير پارامترها تجزيه و تحليل ميشود. حل مثالهاي عددي نشان ميدهد كه هميشه نرخ بالاي بازگشتي منجر به كاهش هزينه‌ي سيستم نمي‌شود و كاهش يا افزايش آن بستگي به ساير پارامترها دارد. همچنين در اين نوشتار هزينههاي سيستم بازنگري موجودي مرور دوره‌يي و دايم نيز مقايسه ميشوند. در هر حال مديران هنگام انتخاب سيستم مديريت موجودي خود بايد به تحليل تمامي پارامترها بپردازند.

IN SUPPORTING ENVIRONMENTAL SUSTAINABILITY, MANAGING PRODUCT RETURNS HAS BECOME A VERY IMPORTANT AND CHALLENGING ISSUE. RESPONDING TO THIS TREND, RESEARCHERS IN MANY PARTS OF THE WORLD HAVE CONDUCTED NUMEROUS STUDIES IN REVERSE LOGISTICS AND REVERSE SUPPLY CHAIN THAT WERE CONSIDERED SEPARATELY FROM THE FORWARD CHANNEL OF SUPPLY CHAINS. MEANWHILE, THERE ARE OPPORTUNITIES TO CREATE ADDED VALUES FROM PRODUCT RETURNS AND TO IMPROVE EFFICIENCY WHEN BOTH CHANNELS ARE CONSIDERED IN AN INTEGRATED WAY, AS A CLOSED LOOP SUPPLY CHAIN. ON THE OTHER HAND, REMANUFACTURING IS A VERY APPEALING OPTION AMONG PRODUCT RECOVERY PROCESSES THAT HAS POTENTIAL TO INCREASE THE VALUE OF PRODUCT RETURNS. INVENTORY MANAGEMENT IN CLOSED-LOOP SUPPLY CHAINS IS MUCH MORE COMPLICATED THAN IN TRADITIONAL FORWARD SUPPLY CHAINS SINCE RETURNS ARE MORE UNCERTAIN THAN DEMANDS IN TERMS OF QUANTITY, QUALITY AND TIMING, AND ALSO VALUATION AND SETTING INVENTORY HOLDING COSTS OF RETURNS ARE NOT STRAIGHT FORWARD. IN ADDITION, CORRELATION BETWEEN DEMANDS AND RETURNS ADDS ANOTHER DIMENSION OF COMPLEXITY TO SUCH SYSTEMS. In this paper, we address the inventory management issue in closed-loop supply chains, and develop deterministic and stochastic models for a three-echelon system with correlated demands and returns. We have analyzed the cost structure of the system from the inventory management point of view, and we developed a deterministic model as well as a stochastic model under continuous review and periodic review for the system. Then, we solved models with Genetic toolbox in MATLAB software and analyzed variation in parameters. Numerical examples shown that may not always lead to decrease cost if return rate increase, But it also depends on another parameters in inventory system. In this paper, we compare cost of continuous review and periodic review for the system. However, when managers want to choose their inventory system, they need to analyze all of parameters and then decide.