| 1. |
- Eveborn, Patrik, et al.
(författare)
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Laps Care : an operational system for staff planning of home care
- 2006
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Ingår i: European Journal of Operational Research. - : Elsevier BV. - 0377-2217 .- 1872-6860. ; 171:3, s. 962-976
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Tidskriftsartikel (refereegranskat)abstract
- The health care system in Sweden and many other countries is facing increasing costs. The major reason is the changing age distribution of the population with more elderly people in need of support. At the same time, health care systems are often very labor and staff intensive. In this paper, we focus on a staff planning problem arising in Sweden where people receive home care from the local authorities. The objective is to develop visiting schedules for care providers that incorporate some restrictions and soft objectives. Each visit has a particular task to be performed, for example: cleaning, washing, personal hygiene and/or nursing activities. Each staff member has skills and each client should, if possible, be visited by the same contact person. The operational situation is continuously changing and planning is done each day. We describe the development of a decision support system Laps Care to aid the planners. The system consists of a number of components including information data bases, maps, optimization routines, and report possibilities. We formulate the problem using a set partitioning model and, for a solution method, we make use of a repeated matching algorithm. The system is currently in operation at a number of home care organizations. We report on the practical impact of the system in the health care organization which was involved in the development. The savings are considerably in terms of saved planning time and in the quality of the routes, as well as the measured quality for the clients. Numerical experiments of the system are presented.
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| 2. |
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| 3. |
- Rönnqvist, Mikael, 1962-, et al.
(författare)
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Home care operations
- 2004
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Ingår i: OR/MS Today. - 1085-1038. ; April, s. 38-43
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Andersson, Gert, et al.
(författare)
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RuttOpt : a decision support system for routing of logging trucks
- 2008
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Ingår i: Canadian Journal of Forest Research. - 0045-5067 .- 1208-6037. ; 38:7, s. 1784-1796
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Tidskriftsartikel (refereegranskat)abstract
- We describe the decision support system RuttOpt, which is developed for scheduling logging trucks in the forest industry. The system is made up of a number of modules. One module is the Swedish road database NVDB, which consists of detailed information of all of the roads in Sweden. This also includes a tool to compute distances between locations. A second module is an optimization routine that finds a schedule, i.e., set of routes for all trucks. This is based on a two-phase algorithm where linear programming and a standard tabu search method are used. A third module is a database storing all relevant information. At the center of the system is a user interface where information and results can be viewed on maps, Gantt schedules, and result reports. The RuttOpt system has been used in a number of case studies and we describe four of these. The case studies have been made in both forest companies and hauling companies. The cases range from 10 to 110 trucks and with a planning horizon ranging between 1 and 5 days. The results show that the system can be used to solve large case studies and that the potential savings are in the range 5%–30%.
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| 5. |
- Bergman, Johan, et al.
(författare)
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Roll cutting at paper mills
- 2002
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Ingår i: Proceedings of the Control Systems 2002. ; , s. 159-163
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Roll cutting has attracted a great deal of research attention. However, most of the development of models and methods in academic research has not considered some key industrial requirements. These are practical production aspects that often create non-tractable optimization problems. In this paper, we study two important problems and show how these can be solved efficiently in an industrial setting. These are operative roll cutting where the number of reels and different patterns should be minimized and real-time cutting, when defects and quality restrictions on ordered rolls are included.
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| 6. |
- Carlsson, D., et al.
(författare)
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Using robust optimization for distribution and inventory planning for a large pulp producer
- 2014
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Ingår i: Computers & Operations Research. - : Elsevier. - 0305-0548 .- 1873-765X. ; 44, s. 214-225
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Tidskriftsartikel (refereegranskat)abstract
- Sodra Cell is a world leading producer of pulp and has a large distribution network for its pulp products. This network includes production mills in Sweden and Norway, terminals in European harbours and inland locations, and many customers. The company uses several transport modes including long chartered vessels, spot vessels, trains, barges and trucks. The company uses a supplier managed inventory with a large proportion of its customers. This makes the logistic planning including transportation and inventory critical, as Sodra Cell has direct responsibility of their customers inventories. However, there is still some uncertainty regarding customer demand and Sodra Cell has traditionally used a safety stock inventory approach to handle this. In this paper, we introduce a robust optimization approach to handle the uncertainty and to establish a distribution plan, together with related inventory management. With this approach there is no need for explicit safety stock levels. This is instead taken into account directly through the robust solution. In the proposed model, we can use practical characterization and historical information on the uncertainty. An important result with this is that we can avoid solutions that are too conservative and costly as in standard robust models. A large case study from Sodra Cell is used to validate the proposed approach against the traditional approach with safety stock. The analysis is based on simulations and it shows that the robust approach is more cost efficient and can be used as a basis in a decision support system.
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| 7. |
- Casimir, Justin, et al.
(författare)
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Skiftning av åkermark för ett effektivare jordbruk
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Antalet gårdar i Sverige minskar medan deras storlek ökar för att kunna hålla verksamheten konkurrenskraftig på marknaden. En vanlig situation är att gården vill expandera snabbare än det finns tillgänglig mark nära gårdscentrum. Detta leder till att gården får längre avstånd till sin åkermark. Detta extra avstånd har en kostnad, både för gårdens lönsamhet och för miljön.En föregående pilotstudie studerade kostnaden för transport av skörd och stallgödsel (spannmål, vall och stallgödsel). Studien visade att kostnader för transporter blir minst halverad om man byter till mark som ligger närmare gården. Denna studie studerade endast fyra gårdar, och inkluderade inte sociala aspekter.Detta fortsättningsprojekt syftar till att få en bättre insikt i de tekniska (geografiska) och även sociala faktorer kopplade till markbyte. Den tekniska delen av projektet innebär utveckling av ett verktyg för att 1) räkna avstånd mellan gårdscentrum och fält i hela Sverige, 2) identifiera bästa matchningar för markbyte mellan gårdar, och därmed minimera avstånd mellan gårdscentrum och fält, och 3) uppskatta potentiella besparingar av drivmedel och kostnader kopplade till markbyte.Våra resultat visar att verktyget ger ett stabilt underlag som beslutstöd. Däremot behövs mer studier för att komma överens om det bästa sättet att implementera verktyget i Sverige, särskilt angående ägarskap, affärsmodell och utveckling av nya funktioner. Den teoretiska potentialen för markbyte mellan två gårdar är uppskattad till 12,4 %.Den sociala delen av projektet undersökte lantbrukares attityder till markbyte. I semi-strukturerade intervjuer med lantbrukare, och seminarium med andra intressenter, undersökte vi hinder, förutsättningar, samt potential för implementering av verktyget. Våra resultat visar att verktyget var positivt mottaget men att det finns fler faktorer att ta hänsyn till t.ex. jordart, odlingsmetod och förtroende.
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| 8. |
- Flisberg, Patrik, et al.
(författare)
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A hybrid method based on linear programming and tabu search for routing of logging trucks
- 2009
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Ingår i: Computers & Operations Research. - : Elsevier BV. - 0305-0548 .- 1873-765X. ; 36:4, s. 1122-1144
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we consider an operational routing problem to decide the daily routes of logging trucks in forestry. This industrial problem is difficult and includes aspects such as pickup and delivery with split pickups, multiple products, time windows, several time periods, multiple depots, driver changes and a heterogeneous truck fleet. In addition, the problem size is large and the solution time limited. We describe a two-phase solution approach which transforms the problem into a standard vehicle routing problem with time windows. In the first phase, we solve an LP problem in order to find a destination of flow from supply points to demand points. Based on this solution, we create transport nodes which each defines the origin(s) and destination for a full truckload. In phase two, we make use of a standard tabu search method to combine these transport nodes, which can be considered to be customers in vehicle routing problems, into actual routes. The tabu search method is extended to consider some new features. The solution approach is tested on a set of industrial cases from major forest companies in Sweden.
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| 9. |
- Flisberg, Patrik, 1972-
(författare)
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Application of operations research in operative planning in the forest industry
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The focus of this thesis is the use of Operations Research for pplications in the forest industry. Optimization models and methods have been developed for problems in the forest supply chain and they have been integrated in decision support systems. The problems considered in this thesis are operative with a planning horizon of less than a month. Short solution times for the methods and the feasibility of the models used are important aspects. The body of this thesis consists of eight research papers where six of them consider operative problems and follows the forest supply chain. The industrial applications include routing of forwarders, routing of logging trucks, a process control problem, and roll cutting problems. The other two papers consider an operative planning problem in the home care sector. They are spin offs from one of the other projects in this thesis. In these applications both linear and nonlinear problems occur.The forwarding problem is to decide routes for forwarders to pick up the small piles of logs the harvesters have left in the harvest areas. The forwarders then put the logs adjacent to forest roads. The logging truck problem is to decide routes for logging trucks to pick up the piles created by the forwarders and transport them to demand points, for example pulp or paper mills. The process control problem appear in the bleaching stage of a pulp mill where the control variables are the bleaching chemical charges. The cost of bleaching chemicals is minimized while a finishing brightness within target values is ensured. Mainly two roll cutting problems are studied. One is to minimize the number of cutting patterns and one is to minimize the number of reels when defects in the papper reels are considered. The solution methods developed for the forwarding problem have also been applied to a routing problem which appears in staff planning for home care operations.The different DSS developed and implemented have been tested and several are in daily industrial use. In each of the papers, we have developed robust OR models and quick and effective OR methods. The savings from using the systems vary but are typically in the range 5-20%.
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| 10. |
- 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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