Abstracts » Business, general

Batch size and stocking levels in multi-echelon repairable systems

Article Abstract:

The ability to identify the optimal order batch size and stocking levels in multi-echelon repairable systems is investigated. Batch size is determined using a power approximation schemes. Optimal stocking levels at the depot and sites for the calculated batch size are discussed using 'one-pass' searches. The power approximation of optimal batch size is investigated, and the optimality of the S-1,S ordering policy is evaluated. Applied to 900 test cases, this technique has proven effective. At local sites, the employment of the batch-ordering policy is more cost-effective than the traditional S-1,S policy, in multi-echelon repairable inventory systems with high demand rates or high set-up costs.

Research, Purchasing, Usage, Stochastic analysis, Factory orders, Economic lot size, Stockroom keeping, Stockrooms

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Service constrained (s,S) inventory systems with priority demand classes and lost sales

Article Abstract:

A model is presented in which (s,S) inventory control system has two priority groups of customers. The model considers excess demand as lost sales and will accept lead times that are arbitrary and deterministic. Having considered the Markov process, an approximate, renewal based model is derived. This is used to develop an heuristic model which minimizes expected costs subject to a fill-rate service constraint. Extensive numerical tests of accuracy and performance regarding the true optimal solution follow. Results suggest good performance, though it deteriorates as the fill-rate requirement and lead time increase.

Methods, Markov processes

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Multi-echelon inventory model for repairable items with emergency lateral transshipments

Article Abstract:

The nodes in multi-echelon inventory networks over wide geographical areas often use lateral transshipments among themselves to provide each other with emergency or routine support. The stockpiling of these nodes can be analyzed and tested for emergency transshipments. Optimal stock levels are found and the tradeoffs involved are assessed.

Transportation, Logistics, Business logistics, Materials management

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