Instrumentation of emergency transshipment for improving flow inventory control in distribution systems
The lateral emergency transshipment in distribution systems consists in the organization of inventory transfers between retailers to face shortage situations. Its implementation leads to adopte an appropriate transshipment policy and harmonize its parameters with inventory policy parameters and inventory control policy. The objective is to ensure a desired service level at minimum cost. This work is situated in this context and focused on the analysis of emergency transshipment benefits in distribution systems faced to random customer demands. Each retailer uses an (R, s, S) inventory control policy.
Our study is related to three different distribution system structures :
• two-echelon, two-retailer inventory system with unit transshipment cost ;
• two-echelon, multi-retailer inventory system with fixed transshipment cost ;
• multi-echelon, two-retailer inventory system with fixed transshipment cost.
For each of these structures, we have interested to analyze the sensitivity of system behavior to input parameters (lead times, demand standard deviation, and number of retailers) and cost parameters (ordering, holding, shortage, and transshipment). Our objective is to determine over a finite horizon the inventory parameters (s, S for both retailers and warehouse) that minimize system total cost and satisfy the desired service level. We have also explored four transshipment policies: all or nothing, standard complete pooling, complete pooling under capacity constraint, and complete pooling under a favorable condition. Firstly, the study is dealt with an analytic approach then solved by numerical experimentations of models based simulation-optimization.
KEYWORDS : Two-echelon inventory systems – Multi-echelon inventory systems – Transshipment – Complete pooling – Models based simulation-optimization