| 1. |
- Flisberg, Patrik, et al.
(författare)
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Billerud Optimizes Its Bleaching Process Using Online Optimization
- 2009
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Ingår i: INTERFACES. - : Institute for Operations Research and the Management Sciences (INFORMS). - 0092-2102 .- 1526-551X. ; 39:2, s. 119-131
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Tidskriftsartikel (refereegranskat)abstract
- Billerud, a Swedish company with four integrated pulp and paper mills, serves specific packaging-market segments. In 2000, the process-engineering department at Billeruds mill in Skarblacka sought to improve the mills bleaching process. It contacted Linkoping University, which collaborated with Eurocon Automation AB to develop a decision-support system, OptCab. Eurocon Automation AB now offers OptCab as a general tool in the market. Its core is an online optimization system that dynamically updates a process description and optimizes the bleaching control process. The system, which has been fully operational since 2004, has provided numerous benefits to Billerud. Chemical use has decreased by approximately 10 percent, saving approximately two million euros since its installation; the environmental impact has also been reduced; and the brightness quality of paper that the mill produces is more uniform and stable. Moreover, OptCab requires less operator time, freeing the operators for development and analysis work.
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| 2. |
- Flisberg, Patrik, et al.
(författare)
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Optimization based planning tools for routing of forwarders at harvest areas
- 2007
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Ingår i: Canadian Journal of Forest Research. - 0045-5067 .- 1208-6037. ; 37:11, s. 2153-2163
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Tidskriftsartikel (refereegranskat)abstract
- The forwarding of logs at harvest areas once the harvesting is done is planned manually by experienced operators. To improve their efficiency and simplify the planning we have developed and tested a decision support system at a major Swedish forest company. The system is based on a combination of a geographic information system (GIS), global positioning system (GPS), and optimization routines to solve the underlying vehicle routing problem. The routes for the forwarders are found by using a repeated matching algorithm. The solution time is short, and it is possible to find routes dynamically in a real-time environment. The geographic information required is found by using a GPS together with data obtained from the bucking software in the harvesters. To show the routes and location of the forwarder, we make use of a GIS that is connected to the GPS. We report on a study with savings in the distance travelled of 8% and numerical tests on the solution methodology. We also compare the proposed solution method with some well-known routing methods.
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| 3. |
- Guajardo, Mario, et al.
(författare)
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Joint optimization of pricing and planning decisions in divergent supply chain
- 2013
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Ingår i: International Transactions in Operational Research. - : Wiley-Blackwell. - 0969-6016 .- 1475-3995. ; 20:6, s. 889-916
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Tidskriftsartikel (refereegranskat)abstract
- In divergent supply chains, such as in the oil industry, processing raw materials results in an outflow of multiple products. Final products are stored at international depots, from where they are ready to be shipped to the markets. Even if one company controls the entire chain, when production and sales organizations are decoupled, a relevant problem is to determine the internal prices of products at depots for achieving coordination. We propose an optimization model involving pricing and production decisions, and several constraints commonly used in divergent chains. In our approach, the producer incorporates the sellers behavior by expressing demand as a function of the internal price. As a result, our model serves as a coordination mechanism in trying to get an overall coordinated integrated solution in a decoupled reality. Numerical examples in single and multiple periods problems show the advantages of our approach over cost-based methods.
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| 4. |
- Guajardo, Mario, et al.
(författare)
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Speciality oils supply chain optimization: From a decoupled to an integrated planning approach
- 2013
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Ingår i: European Journal of Operational Research. - : Elsevier. - 0377-2217 .- 1872-6860. ; 229:2, s. 540-551
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Tidskriftsartikel (refereegranskat)abstract
- We study a problem of tactical planning in a divergent supply chain. It involves decisions regarding production, inventory, internal transportation, sales and distribution to customers. The problem is motivated by the context of a company in the speciality oils industry. The overall objective at tactical level is to maximize contribution and, in order to achieve this, the planning has been divided into two separate problems. The first problem concerns sales where the final sales and distribution planning is decentralized to individual sellers. The second problem concerns production, transportation and inventory planning through refineries, hubs and depots and is managed centrally with the aim of minimizing costs. Due to this decoupling, the solution of the two problems needs to be coordinated in order to achieve the overall objective. In the company, this is pursued through an internal price system aiming at giving the sellers the incentives needed to align their decisions with the overall objective. We propose and discuss linear programming models for the decoupled and integrated planning problems. We present numerical examples to illustrate potential effects of integration and coordination and discuss the advantages and disadvantages of the integrated over the decoupled approach. While the total contribution is higher in the integrated approach, it has also been found that the sellers contribution can be considerably lower. Therefore, we also suggest contribution sharing rules to achieve a solution where both the company and the sellers attain a better outcome under the integrated planning.
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| 5. |
- Lidestam, Helene, et al.
(författare)
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Use of Lagrangian decomposition in supply chain planning
- 2011
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Ingår i: Mathematical and computer modelling. - : Elsevier. - 0895-7177 .- 1872-9479. ; 54:9-10, s. 2428-2442
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Tidskriftsartikel (refereegranskat)abstract
- The integrated planning of transportation of raw material, production and distribution of products of the supply chain for a large pulp company is studied. The planning period is one year and a number of time periods are considered. The tactical decisions included in the model regard transportation of raw materials from harvest areas to pulp mills, production mix and contents at pulp mills, distribution of pulp products from mills to customers either via terminals or directly, and the selection of potential orders and their levels at customers. A mixed integer linear programming model for the supply chain problem is developed. The main solution method in this paper is a Lagrangian heuristic method based on Lagrangian decomposition. The heuristic divides the problem into two subproblems representing different physical stages in the supply chain, each including several time periods. The advantage of the proposed solution approach is that it generates feasible solutions of high quality in short time. A number of cases based on real data is analysed.
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