Optimal empty vehicle repositioning and fleet-sizing for two-depot service systems |
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Authors: | Dong-Ping Song Christopher F. Earl |
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Affiliation: | 1. International Shipping and Logistics Group, The Business School, University of Plymouth, Plymouth, PL4 8AA, UK;2. Department of Design and Innovation, Open University, Walton Hall, Milton Keynes, MK7 6AA, UK |
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Abstract: | This paper considers the problem of determining optimal control policies for empty vehicle repositioning and fleet-sizing in a two-depot service system with uncertainties in loaded vehicle arrival at depots and repositioning times for empty vehicles in the fleet. The objective is to minimise the sum of the costs incurred by vehicle maintenance, empty vehicle repositioning and vehicle leasing. A novel integrated model is presented. The optimal empty repositioning policy for a particular fleet size is shown to be of the threshold control type. The explicit form of the cost function under such threshold controls is obtained. The optimal threshold values and fleet-size are then derived. Numerical examples are given to demonstrate the results. |
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Keywords: | Transportation Dynamic programming Stochastic Empty repositioning Fleet-sizing |
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