Mikael Rönnqvist

Laps Care : an operational system for staff planning of home care

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 ...

Cost Allocation in Collaborative Forest Transportation

Transportation planning is an important part of the wood flow chain in forestry. There are often several forest companies operating in the same region and co-ordination between two or more companies is rare. However, there is an increasing interest in collaborative planning as the potential savings are large, often in the range 5-15%. A key question is how savings should be distributed among the participants. In this paper we investigate a number of possibilities based on economic models including Shapley value, the nucleolus, separable and non-separable costs, shadow prices and volume weights. We also propose a new allocation method based on finding as equal relative profits as possible among the participants. A case study including eight forest companies is described and analyzed.

Supply chain modelling of forest fuel

We study the problem of deciding when and where forest residues are to be converted into forest fuel, and how the residues are to be transported and stored in order to satisfy demand at heating pla ...

An exact algorithm for the capacitated facility location problems with single sourcing

Facility location problems are often encountered in many areas such as distribution, transportation and telecommunication. We describe a new solution approach for the capacitated facility location problem in which each customer is served by a single facility. An important class of heuristic solution methods for these problems are Lagrangian heuristics which have been shown to produce high quality solutions and at the same time be quite robust. A primal heuristic, based on a repeated matching algorithm which essentially solves a series of matching problems until certain convergence criteria are satisfied, is incorporated into the Lagrangian heuristic. Finally, a branch-and-bound method, based on the Lagrangian heuristic is developed, and compared computationally to the commercial code CPLEX. The computational results indicate that the proposed method is very efficient.

Innovative Applications of O.R.Cost allocation in collaborative forest transportation

Transportation planning is an important part of the supply chain or wood flow chain in forestry. There are often several forest companies operating in the same region and collaboration between two or more companies is rare. However, there is an increasing interest in collaborative planning as the potential savings are large, often in the range 5–15%. There are several issues to agree on before such collaborative planning can be used in practice. A key question is how the total cost or savings should be distributed among the participants. In this paper, we study a large application in southern Sweden with eight forest companies involved in a collaboration. We investigate a number of sharing mechanisms based on economic models including Shapley value, the nucleolus, separable and non-separable costs, shadow prices and volume weights. We also propose a new allocation method, with the aim that the participants relative profits are as equal as possible. We use two planning models, the first is based on direct flows between supply and demand points and the second includes backhauling. We also study how several time periods and geographical distribution of the supply and demand nodes affect the solutions. Better planning within each company can save about 5% and collaboration can increase this about another 9% to a total of 14%. The proposed allocation method is shown to be a practical approach to share the overall cost/savings.

Supply chain management in forestry - Case studies at Södra Cell AB

The use of supply chain management and optimisation is of increasing importance in the forest industry. The overall wood-flow starts with standing trees in forests and continues with harvesting, bucking, sorting, transportation to terminals, sawmills, pulp mills, paper mills and heating plants, conversion into products such as pulp, paper, lumber, and ends at different customers. Many planning problems arise along the chain and these cover different time horizons. Co-ordinating the wood-flow is a vital concern for many companies. We study Sodra, one of the larger Swedish forest companies, which is involved in all stages of the wood-flow. We focus in particular on Sodra Cell AB, a company within Sodra, which is responsible for pulp production. We describe the operations at Sodra Cell and the decision support tools used for supply chain planning. We describe five major projects or cases which focus on improving their supply chain management and optimisation. These cases include the introduction of new technologies for sales and orders, new distribution structures using terminals, and the development of integrated optimisation models and methods.

Optimization in forestry

Abstract. Optimization models and methods have been used extensively in the forest industry. In this paper we describe the general wood-flow in forestry and a variety of planning problems. These cover planning periods from a fraction of a second to more than one hundred years. The problems are modelled using linear, integer and nonlinear models. Solution methods used depend on the required solution time and include for example dynamic programming, LP methods, branch & bound methods, heuristics and column generation. The importance of modelling and qualitative information is also discussed.

Using Operational Research for Supply Chain Planning in the Forest Products Industry

Abstract Over the years, Operational Research (OR) has been used extensively to support the forest products industry and public forestry organizations (e.g., governments, environmental protection groups) in their respective planning activities concerning the flow of wood fiber from the forest to the customer. The applications deal with a wide range of problems, ranging from long-term strategic problems related to forest management or company development to very short-term operational problems, such as planning for real-time log/chip transportation or cutting. This paper presents an overview of the different planning problems and reviews the past contributions in the field of forestry, with a focus on applications and problem descriptions. In the context of the 50th anniversary of the Canadian Operational Research Society, this paper also recognizes the contributions of many Canadian researchers to the field of forestry management.

An exact method for the two-echelon, single-source, capacitated facility location problem

Facility location problems form an important class of integer programming problems, with applications in the telecommunication, distribution and transportation industries. In this paper we are conc ...

Supply chain optimization in the pulp mill industry--IP models, column generation and novel constraint branches

We study the supply chain problem of a large international pulp producer with five pulp mills located in Scandinavia. The company currently uses manual planning for most of its supply chain, which ...