8 research outputs found
Downstream logistics optimization at EWOS Norway
The Norwegian company EWOS AS produces fish feed for the salmon farming industry, supplying approximately 300 customers spread along the coast of Norway. The feed is produced at three factory locations and distributed by a fleet of 10 dedicated vessels. The high seasonality of the demand and the large number of customers make the distribution planning a substantial challenge. EWOS handles it by operating a system of mostly fixed routes with decentralized planning at each factory. The distribution can be described as a multi-depot vehicle routing problem with time windows, multiple vehicle usage, inter-depot routes, heterogeneous fleet and a rolling horizon. The paper presents a mathematical model for this problem, which is solved by heuristics and meta heuristics. Based on detailed historical data collected by EWOS during the autumn of 2010, the model has proposed a dynamic set of routes with a significant reduction of travelled distance - close to 30% - and an increase of average vessel fill-rate - from 60% up to 95%. This implies a substantial fuel saving, with a positive environmental impact, and also a potential for downscaling the fleet, with additional considerable cost savings for the company.publishedVersio
Conjuntos de Bases Gaussianas Correlacionados nĂŁo RelativĂsticos e RelativĂsticos: Aplicação em Cálculos de Constantes EspectroscĂłpicas e Propriedades ElĂ©tricas e MagnĂ©ticas Moleculares.
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Previous issue date: 2009-12-18Conjunto de bases contraĂdo de qualidade dupla zeta (DZ) para os átomos de K atĂ© Kr Ă© apresentado. Ele foi determinado a partir de um conjunto de bases totalmente otimizado de funções tipo Gaussianas primitivas geradas em cálculos Hartree-Fock atĂ´micos. Conjuntos de
funções de polarização Gaussianas otimizadas ao nĂvel de teoria de perturbação de Møller-Plesset de segunda ordem foram adicionados ao conjunto de bases DZ. Isto estende um trabalho anterior de conjunto de bases DZ de contração segmentada para os átomos H-Ar. A
partir deste conjunto, usando os funcionais nĂŁo-hĂbrido BP86 e o hĂbrido B3LYP, energia de dissociação, parâmetros geomĂ©tricos, freqĂĽĂŞncia vibracional harmĂ´nica e momento de dipolo elĂ©trico de um conjunto de molĂ©culas foram calculados e comparados com resultados obtidos com outros conjuntos de bases e com dados experimentais reportados na literatura. Em adição, deslocamentos quĂmicos de ressonância magnĂ©tica nuclear do 57Fe e 77Se em Fe(C5H5)2, H2Se
e CSe2 foram calculados usando a teoria do funcional da densidade e orbitais atĂ´micos gaugeincluding e, entĂŁo, comparados com valores experimentais e teĂłricos previamente publicados na literatura. Exceto para deslocamento quĂmico, verifica-se que nossos resultados dĂŁo a
melhor concordância com valores de referência e experimentais.
Conjuntos de bases Gaussianas aumentados de qualidades dupla e tripla zeta de valĂŞncia mais funções de polarização para os átomos de K e de Sc atĂ© Zn sĂŁo tambĂ©m apresentados. Eles foram gerados a partir dos conjuntos nĂŁo aumentados para todos elĂ©trons pela adição de funções difusas (simetrias s, p, d, f, g), que foram otimizadas para os estados fundamentais dos ânions. A partir desses conjuntos, cálculos Hartree-Fock, de teorias de perturbação Mφller-Plesset de segunda ordem e do funcional da densidade de momento de dipolo elĂ©trico e polarizabilidade de dipolo de um conjunto de molĂ©culas foram realizados.
Finalmente, conjuntos de bases Gaussianas contraĂdas Douglas-Kroll-Hess (DKH) de qualidades dupla, tripla e quádrupla zeta de valĂŞncia mais funções de polarização (XZP, X=D, T e Q, respectivamente) para os átomos de H, Li, Be, Na e Mg e DZP e TZP para K-Zn sĂŁo apresentados. Eles foram determinados a partir dos conjuntos de bases nĂŁo relativĂsticos correspondentes gerados previamente por Jorge e colaboradores. NĂłs recontraĂmos os conjuntos de bases XZP originais, isto Ă©, os valores dos coeficientes de contração foram reotimizados usando o Hamiltoniano DKH relativĂstico. O efeito escalar relativĂstico ao nĂvel de teoria Coupled-Cluster na energia de ionização de alguns átomos e energia de dissociação
e parâmetros geométricos de um conjunto de moléculas é discutido.
Todos resultados obtidos neste trabalho foram comparados com valores teĂłricos e experimentais disponĂveis na literatura
Model celoÄŤĂselnĂ©ho lineárnĂho programovánĂ pro plánovánĂ Ĺ™ĂÄŤnĂ pĹ™epravy ve spoleÄŤnosti Omya
The article presents a mathematical model for barge transport planning, which is part of a decision support system recently taken into use by the Swiss company Omy. The barge-planning problem falls in the category of inventory routing problems and is further characterized with multiple products, heterogeneous fleet, vehicle compartments, multiple customer visits, bounded customer inventories, etc.ÄŚlánek prezentuje matematickĂ˝ model pro plánovánĂ Ĺ™ĂÄŤnĂ pĹ™epravykterĂ˝ je součástĂ systĂ©mu pro podporu rozhodovánĂ, nedávno uvedenĂ©ho do praxe Ĺ vĂ˝carskou spoleÄŤnostĂ Omya. ProblĂ©m plánovánĂ pĹ™epravy spadá do kategorie "inventory routing problem" a je dále charakterizován vĂce produkty, heterogennĂ flotilou, nákladovĂ˝mi prostory, kombinovanĂ˝mi cestami, omezenĂ˝mi skladovacĂmi zásobami u zákaznĂkĹŻ atd
The single (and multi) item profit maximizing capacitated lot–size (PCLSP) problem with fixed prices and no set–up
summary:This paper proposes a specialized LP-algorithm for a sub problem arising in simple Profit maximising Lot-sizing. The setting involves a single (and multi) item production system with negligible set-up costs/times and limited production capacity. The producer faces a monopolistic market with given time-varying linear demand curves
Omya Hustadmarmor Optimizes Its Supply Chain for Delivering Calcium Carbonate Slurry to European Paper Manufacturers
International audienceThe 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 Møre 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 US4 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