The Norwegian company Omya Hustadmarmor supplies calcium carbonate slurry to European paper manufacturers from a single processing plant, using chemical tank ships of various sizes to transport its products. Transportation costs are lower for large ships than for small ships, but their use increases planning complexity and creates problems in production. In 2001, the company faced overwhelming operational challenges and sought operations-research-based planning support. The CEO, Sturla Steinsvik, contacted More Research Molde, which conducted a project that led to the development of a decision-support system (DSS) for maritime inventory routing. The core of the DSS is an optimization model that is solved through a metaheuristic-based algorithm. The system helps planners to make stronger, faster decisions and has increased predictability and flexibility throughout the supply chain. It has saved production and transportation costs close to US$7 million a year. We project additional direct savings of nearly US$4 million a year as the company adds even larger ships to the fleet as a result of the project. In addition, the company has avoided investments of US$35 million by increasing capacity utilization. Finally, the project has had a positive environmental effect by reducing overall oil consumption by more than 10 percent
Brahimi, N.; Dauzere-Peres, S., Najid, N. & Nordli, Atle (2006)
Single item lot sizing problems
European Journal of Operational Research, 168(1), s. 1- 16.
A state-of-the-art of a particular planning problem, the Single Item Lot Sizing Problem (SILSP), is given for its uncapacitated and capacitated versions. First classes of lot sizing problems are briefly surveyed. Various solution methods for the Uncapacitated Single Item Lot Sizing Problem (USILSP) are reviewed. Four different mathematical programming formulations of the classical problem are presented. Different extensions for real-world applications of this problem are discussed. Complexity results of the Capacitated Single Item Lot Sizing Problem (CSILSP) are given together with its different formulations and solution techniques. (c) 2004 Published by Elsevier B.V.
Halskau, Øyvind; Gribkovskaia, Victoria & Nordli, Atle (2006)
Economic order quantities assuming generalised order costs
Proceedings of the annual conference for nordic researchers in logistics (NOFOMA)
Using sea transportation with increasing capacity usually leads to a smaller transportation cost per unit. In this paper we introduce such economies of scale in the classical Harris- Wilson cost function. We show that the classical EOQ formulas will take different shapes depending on the new cost function, indicating that the classical formulas are specialisations of more general settings. Our new formulation uses a common power function to model the economies of scale. It is well known that the deviations from the classical Harris-Wilson order quantity are fairly insensitive as far as the total logistic costs are concerned. We show that this insensitivity becomes even more noticeable if economies of scale are increased. Finally, we offer real-life examples of the above-mentioned economies of scale.
Nordli, Atle & Engebrethsen, Erna Senkina (2010)
Transportation lot sizing: Research topics and practical aspects
[Academic lecture]. International Workshop on Lot Sizing.
Nordli, Atle (2008)
Impact of Optimal Storage Capacity Allocation on Transportation
[Academic lecture]. International conference on flexible supply chains in a global economy.
Dauzère-Pérès, Stéphane & Nordli, Atle (2007)
Optimal logistics at Omya Hustadmarmor
[Article in business/trade/industry journal]. ?, 2(34), s. 30- 34.
Economic order quantities assuming generalised order costs
[Academic lecture]. The 18th annual NOFOMA Conference.
Olstad, Asmund; Haugen, Kjetil Kåre, Nordli, Atle, Dauzère-Peres, Stéphane, Reistad, Alf, Myrstad, Per Olav & Teistklub, Geir (2006)
Omya Hustadmarmor : optimizing the supply chain of calcium carbonate slurry to the European paper making industry
[Academic lecture]. 2006 INFORMS Conference on OR/MS Practice.
Omya Hustadmarmor supplies calcium carbonate slurry to European paper manufacturers. The products are transported out from a single processing plant. In 2001, the company was facing a situation with overwhelming operational challenges and decided to look for OR-based planning support. Møre Research Molde conducted a project that led to the development of a Decision Support System for maritime inventory routing, providing planners with the necessary support to make stronger and faster decisions. This has increased both predictability and flexibility throughout the supply chain, resulting in direct savings in production and transportation costs of close to $7US million a year. Also projected are additional direct savings of nearly $4 million a year, since even larger ships can be added to the fleet. Investments of $35 million have been avoided due to increased capacity utilization.
Brahimi, N.; Dauzére-Peres, Stèphane, Najid, N. & Nordli, Atle (2002)
Review of the Single Item Lot Sizing Problem
[Academic lecture]. IEEE International Conference on Systems, Man, and Cybernetics.
Voksende oppmerksomhet omkring miljøspørsmål gjør det naturlig å undersøke hvordan logistikkmodeller kan modifiseres for å kunne fungere under nye rammebetingelser som følger av økt miljøfokus. Logistikkmodeller er i denne rapporten definert som det analytiske og numeriske apparat som gir beslutningsstøtte til bedriftsinterne prosesser relatert til materialflyt. Det er fokusert hovedsaklig på de tre tradisjonelle emneområdene innenfor logistikk, nemlig innkjøp/lager, produksjon/lager og transport. Rapporten er delt i to hoveddeler: Første del er en omfattende litteraturoversikt. Det er fokusert på tre ulike tilnærminger til miljøproblematikken, henholdsvis modeller for avfallsbehandling, modeller for gjenvinning og mer gjennomgripende modeller som inkorporerer redusert ressursbruk. Andre del av rapporten er analysedelen. Her blir hovedfokus satt på hvilke konsekvenser offentlige reguleringer i form av henholdsvis miljøbeskrankninger og miljøavgifter vil ha for bedrifters logistikkfunksjon. Virkning på tradisjonelle deterministiske og stokastiske styringsmodellers kompleksitet av henholdsvis miljøavgifter og miljøbeskrankninger analyseres. Resultatene viser at mens en innføring av en miljøavgift bare medfører en justering av inputparametre i modellene, så vil en innføring av nye beskrankninger implisere en økt kompleksitet som gjør at utskifting av eksisterende styringsmodeller ikke er til å unngå. Tradisjonelle modeller finnes i dag innebygget i de fleste styringssystemer. En oppgradering for å takle ekstra miljøbeskrankninger kan medføre betydelige kostnader i form av programutvikling, konsulenthonorarer og opplæring. Avslutningsvis introduseres en ramme som kan brukes til å modellerer markedsrelaterte problemstillinger knyttet til assymetrisk informasjon og markedskobling. Assymetrisk informasjon betyr i dette tilfellet at produsent og konsument har svært forskjellig kunnskapsnivå når det gjelder et produkts virkelige miljøegenskaper. Markedskobling gjenspeiler at lønnsomheten av en bedrifts "grønne" tiltak også vil være avhengig av konkurrentenes atferd.