Economic lot scheduling problems with new and different cost approximations
2008 (English)In: Book of Abstracts, 15th International Symposium on Inventories, Budapest, Hungary, Aug. 2008, 2008Conference paper, Meeting abstract (Other academic)
This paper considers scheduling the production of several different items on a single machine with constrained capacity, commonly known as the Economic Lot Scheduling Problem (ELSP). Nilsson and Segerstedt (2008) show that even for ELSP problems with high utilisation it is possible to find a feasible solution (fulfilling feasibility conditions from Eilon (1962), Goyal (1975), Segerstedt (1999)), but the real inventory holding cost is often higher than the common used approximation. This is because the production of an item has to start before the inventory of the same item reaches zero, to avoid a future shortage of the same item. The common cycle solution always presents the "right" inventory holding cost; but diversifications of the frequencies may not accomplish what it promises. Most traditional approaches for the ELSP consider only the sum of the setup cost and inventory holding cost and provide cyclicschedules that minimize this sum. In practice, there are not only costs for setups and inventory holding, but also costs for operating the production facility due to e.g. electricity, service, maintenance, tools, operators etc, which depend on the number of hours the facilityis operating per working day (cf. Brander and Segerstedt (2008).Our investigations in this paper find a solution method that can evaluate different schedulesdue to different frequencies, and find the right inventory holding cost without the common approximation and combine it with a facility time variable cost as in this paper. We start from an idea from Cooke et al (2004) and van der Sluis (2006). A mixed integer programming (MIP) problem that from a common time period and integer number of frequencies for each item minimises costs and avoids shortages. But we try to avoid MIP and its long calculation times, when in our case to find the best solution several MIP calculations have to be done after each other.
Place, publisher, year, edition, pages
Research subject Industrial Logistics
IdentifiersURN: urn:nbn:se:ltu:diva-40035Local ID: f0152710-ba24-11dd-b223-000ea68e967bOAI: oai:DiVA.org:ltu-40035DiVA: diva2:1013557
International Symposium on Inventories : 22/08/2008 - 26/08/2008
Godkänd; 2008; 20081124 (keni)2016-10-032016-10-03Bibliographically approved