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Planering av stränggjutningsproduktion: En heruistisk metod
Linköping University, Department of Mathematics. Linköping University, Faculty of Science & Engineering.
Linköping University, Department of Mathematics. Linköping University, Faculty of Science & Engineering.
2017 (Swedish)Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
Abstract [sv]

Detta arbete syftar till att undersöka om det är möjligt att med en heuristisk metod skapa giltiga lösningar till ett problem vid planering av stränggjutningsproduktion på SSAB. Planeringsproblemet uppstår när stål av olika sorter ska gjutas under samma dag. Beroende på i vilken ordning olika kundordrar av stål gjuts uppstår spill av olika storlek. Detta spill ska minimeras och tidigare arbete har genomförts på detta problem och resulterat i en matematisk modell för att skapa lösningar till problemet. Det tar i praktiken lång tid att hitta bra lösningar med modellen och frågeställningen är om det går att göra detta med en heuristisk metod för att kunna generera bra lösningar snabbare.

Med inspiration från Variable Neighbourhood Search, Simulated Annealing och tabusökning har heuristiker skapats, implementerats och utvärderats mot den matematiska modellen. En av heuristikerna presterar bättre än den matematiska modellen gör på 10 minuter. Matematiska modellens resultat efter 60 minuter körtid är bättre än den utvecklade heuristiken, men resultaten är nära varandra. Körtiden för heuristiken tar signifikant mindre tid än 10 minuter.

Abstract [en]

This study aims to investigate if it is possible to use a heuristic method to create feasible solution in a Cast Batching Problem at SSAB. The problem occurs when different kinds of steel should be cast during the same day. Depending on which order the groups of different steel is placed different amounts of waste is produced, the goal is to minimize this waste. Earlier work has been done on this problem and resulted in a mathematical model to create feasible solutions to this problem. In practice the time it takes to create good solutions are long and the question is if it is possible to use a heuristic method to generate good solutions in a shorter amount of time.

Drawing upon inspiration from metaheuristics such as Variable Neighbourhood Search, Simualted Annealing and Tabu Search multiple heuristics have been created, implemented and evaluated against the mathematical model. One of the heuristics perform better than the mathematical model does in 10 minutes. The result from the mathematical model after 60 minutes is slightly better than the heuristic, but the results are similar. With regards to running time the heuristic takes considerably less time than 10 minutes.

Place, publisher, year, edition, pages
2017. , p. 55
Series
LiTH-MAT-EX-2017/02-SE
Keywords [en]
Cast Batching Problem, Variable Neighbourhood Search, Simulated Annealing, Tabu Search
Keywords [sv]
Stränggjutningsproblem, Variable Neighbourhood Search, Simulated Annealing, tabusökning
National Category
Other Mathematics
Identifiers
URN: urn:nbn:se:liu:diva-136271OAI: oai:DiVA.org:liu-136271DiVA, id: diva2:1086923
Subject / course
Applied Mathematics
Presentation
2017-02-16, 10:00 (English)
Supervisors
Examiners
Available from: 2017-04-05 Created: 2017-04-04 Last updated: 2017-04-05Bibliographically approved

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Äng, OscarTrygg, Alexander
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