| 11. |
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| 12. |
- Engevall, Stefan, 1966-, et al.
(författare)
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The traveling salesman game : An application of cost allocation in a gas and oil company
- 1998
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Ingår i: Annals of Operations Research. - : Springer-Verlag New York. - 0254-5330 .- 1572-9338. ; 82, s. 203-218
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Tidskriftsartikel (refereegranskat)abstract
- In this article, a cost allocation problem that arises in a distribution planning situation atthe Logistics Department at Norsk Hydro Olje AB is studied. A specific tour is considered,for which the total distribution cost is to be divided among the customers that are visited.This problem is formulated as a traveling salesman game, and cost allocation methods basedon different concepts from cooperative game theory, such as the nucleolus, the Shapleyvalue and the t-value, are discussed. Additionally, a new concept is introduced: the demandnucleolus. Computational results for the Norsk Hydro case are presented and discussed.
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| 13. |
- Henningsson, Mathias, 1970-, et al.
(författare)
-
A ring network design problem and heuristics for generating a set of feasible rings
- 2003
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We discuss the problem of designing a telecommunication network with the survivability requirement that the network should be composed of connected rings of links. The work design problem is then to choose links from a given network, and compose them into a number of rings. Furthermore, the rings should be connected at certain transit nodes. The traffic between rings may pass through other rings. Each ring is associated with a certain fixed cost depending on the length of the ring. We describe the problem, modeled as a linear integer programming problem. We find a feasible solution to the problem by first find good rings in the network using two heuristics, and then solve the optimization model using only these rings. Finally, we give some computational results for different networks.
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| 14. |
- Henningsson, Mathias, 1970-, et al.
(författare)
-
A ring network design problem solved by a ring generation and allocation approach
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The development of optical fibers in telecommunications has lead large changes in the field. When design a telecommunication network, capacity nowadays is cheap, and the minimal cost design tends to be a tree. Since such a design is very vulnerable for link or node failures, one often wish to include some kind of survivability requirement, for example that the network should be two-edge-connected or two-node-connected. Another form of design model is to prescribe that the network should be composed of connected rings of links. The network design problem is then to choose links from a give network, and compose them into a number of rings. Furthermore, the rings should be connected at certain transit nodes. Each possible ring is associated with a certain fixed cost, and all links in a certain ring are given the same capacity. Traffic between rings may pass through other rings, which is an important element of the problem. Finally, reserve capacity allocation according to certain principles is included. We describe the problem, modeled as a linear integer programming problem, and discuss different formulations and different solution methods. As the problem is quite difficult, we focus on heuristic solution methods, including elements of column generation and Lagrangean relaxation.
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| 15. |
- Häll, Carl Henrik, 1978-, et al.
(författare)
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Evaluation of an integrated public transport system: a simulation approach
- 2008
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Ingår i: Archives of Transport. - Warsaw : Univ. of Technology, Institute of Transport. - 0866-9546. ; 20:1-2, s. 29-46
-
Tidskriftsartikel (refereegranskat)abstract
- Integrated public transportation service is a new interesting form of service combining a fixed route service with a demand responsive service. When designing such a service, it is important to analyse and evaluate how the attractiveness and operating costs for the service depend on the type of demand responsive service used, the design parameters related to the fleet of vehicles, the structure of the transportation network and on the personal service commitments made to the passengers. In this paper, we show how simulation can be used to perform these analyses. The performed simulations also give guidelines to help operators of public transport to design the service. The evaluation is made using the LlTRES-2 public transport modelling system. The results show the importance of the design of the demand responsive part of the integrated service.
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| 16. |
- Häll, Carl Henrik, 1978-, et al.
(författare)
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Simulation and evaluation of integrated public transport
- 2005
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Ingår i: Advanced OR and AI Methods in Transportation, Proceedings of the 10th Jubilee Meeting of the EURO Working Group on Transportation,2005. - Poznan, Poland : Publishing House of the Poznan University of Technology. ; , s. 271-
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Konferensbidrag (refereegranskat)
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| 17. |
- Häll, Carl Henrik, 1978-, et al.
(författare)
-
The Integrated Dial-a-Ride Problem
- 2009
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Ingår i: Public Transport. - Berlin / Heidelberg : Springer. - 1866-749X .- 1613-7159. ; 1:1, s. 39-54
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a formulation of the Integrated Dial-a-Ride (IDARP). This problem is to schedule dial-a-ride requests, where some part of each journey may be carried out by a fixed route service. The IDARP is a generalization of the Dial-a-Ride Problem. An arc-based formulation is proposed, and it is shown how the model can be made easier to solve by arc elimination, variable substitution and the introduction of subtour elimination constraints. Small instances of the IDARP can be solved using an exact solution method, and one such instance is studied. We also describe how input and output data can be created and visualized in a geographic information system.
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| 18. |
- Lundgren, Jan, 1957-, et al.
(författare)
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Optimeringslära
- 2003
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Annan publikation (populärvet., debatt m.m.)
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| 19. |
- Melin, Kennet
(författare)
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Optimization modelling and methods for freight transportation in scheduled railways
- 2002
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the planning process of a freight railway transportation company, a number of optimization problems arise. In this thesis, we study two of them; empty freight car distribution and line planning.The empty freight car distribution process is the planning and realization of empty freight car movement in order to remedy spatial imbalances of cargo flows. An efficient utilization of empty cars helps keeping investment costs low. One objective of the empty freight car distribution process is to group empty cars in suitable blocks. In this context, the multicommodity network flow problem with fixed path costs is applicable. The problem is a difficult mixed integer programming problem, and we develop and implement a Lagrangean heuristic for solving the problem. Numerical results are also presented.Line planning is the first stage in the process of making a time table. The aim is to decide paths for trains to follow, and frequencies with which trains run in the paths. A model for the line planning problem for freight transportation in scheduled railways is presented. We also present a mode! for a special case of this problem where only direct trains are used. For the mode! in the direct train case of line planning. two heuristics are developed and evaluated: the first one is a rounding heuristic and the other is a tabu search algorithm.
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| 20. |
- Norin, Anna, 1977-, et al.
(författare)
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A GRASP Heuristic for Scheduling De-icing trucks at Stockholm Arlanda Airport
- 2007
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Ingår i: 6th Eurocontrol Innovative Research Workshop and Exhibition,2007.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- It is a fact that the most delays in the Air Transportation System (ATS) today occur at the airport. One reason for this is the large number of actors operating at the airport and the scarcity of communication between them and other parts of the ATS. Airport Logistics is a concept developed to survey all the flows of ehicles, people, material and information, which can be found on and around the airport. The objective is to increase efficiency, where one part is to decrease the delays. As an initial step, the turn-around process is analysed and an optimization model for the planning of de-icing trucks is implemented. The model shows that large savings can be made both by reducing the travelling distances for the trucks and reducing the delays the de-icing process is causing the ATS. However, most important is the advantage of having a plan for how the de-icing trucks should be utilized, something that is missing today.
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