Jan A. Persson
Malmö University
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Publication
Featured researches published by Jan A. Persson.
European Journal of Operational Research | 2005
Jan A. Persson; Maud Göthe-Lundgren
In this paper we suggest an optimization model and a solution method for a shipment planning problem. This problem concerns the simultaneous planning of how to route a fleet of ships and the planning of which products to transport in these ships. The ships are used for moving products from oil refineries to storage depots. There are inventory levels to consider both at the refineries and at the depots. The inventory levels are affected by the process scheduling at the refineries and demand at the depots. The problem is formulated using an optimization model including an aggregated representation of the process scheduling at the refineries. Hence, we integrate the shipment planning and the process scheduling at the refineries. We suggest a solution method based on column generation, valid inequalities, and constraint branching. The solution method is tested on data provided by the Nynas oil refinery company and solutions are obtained within 4 hours, for problem instances of up to 3 refineries, 15 depots, and 4 products when considering a time horizon of 42 days.
Simulation Modelling Practice and Theory | 2012
Johan Holmgren; Paul Davidsson; Jan A. Persson; Linda Ramstedt
We present the Transportation And Production Agent-based Simulator (TAPAS), which is an agent-based model for simulation of transport chains that can be used, e.g., for analysis of transport-related policy and infrastructure measures. TAPAS is more powerful than traditional approaches to freight transport analysis, as it explicitly models production and customer demand, and it captures the interaction between individual transport chain actors, their heterogeneity and decision making processes, as well as time aspects. Whereas traditional approaches rely on assumed statistical correlation, TAPAS relies on causality, i.e., the focus is on the decisions and negotiations that lead to activities. TAPAS is composed of two connected layers, one that simulates the physical activities, e.g., production and transportation, and one that simulates the decision making and interaction between actors. We illustrate TAPAS with a scenario in which the consequences of three transport policy and infrastructure measures are studied.
agent and multi agent systems technologies and applications | 2007
Paul Davidsson; Jan A. Persson; Johan Holmgren
The strengths and weaknesses of agent-based approaches and classical optimization techniques are compared. Their appropriateness for resource allocation problems were resources are distributed and demand is changing is evaluated. We conclude that their properties are complementary and that it seems beneficial to combine the approaches. Some suggestions of such hybrid systems are sketched and two of these are implemented and evaluated in a case study and compared to pure agent and optimization-based solutions. The case study concerns allocation of production and transportation resources in a supply chain. In one of the hybrid systems, optimization techniques were embedded in the agents to improve their decision making capability. In the other system, optimization was used for creating a long-term coarse plan which served as input the agents that adapted it dynamically. The results from the case study indicate that it is possible to capitalize both on the ability of agents to dynamically adapt to changes and on the ability of optimization techniques for finding high quality solutions.
hawaii international conference on system sciences | 2005
Johanna Törnquist; Jan A. Persson
This paper addresses the problem of solving conflicts in railway traffic that arise due to disturbances. It is formulated as a problem of re-scheduling meets and overtakes of trains and has been dealt with in a two-level process. The upper level handles the order of meets and overtakes of trains on the track sections while the lower level determines the start and end times for each train and the sections it will occupy. A linear optimization model is used in the lower level process and provides the upper level with dual prices of the binding constraint in order to generate potentially good alternative meets and overtakes, i.e. generating a suitable neighborhood to the current solution. Simulated Annealing (SA) and Tabu Search (TS) have been applied separately on the top level. The values of their generated solutions were compared to the optimum, showing that TS outperformed SA.
multi agent systems and agent based simulation | 2004
Markus Bergkvist; Paul Davidsson; Jan A. Persson; Linda Ramstedt
A simulation-based tool is described which will be used to investigate how the actors in a transport chain are expected to act when different types of governmental control policies are applied, such as, fuel taxes, road tolls, vehicle taxes and requirements on vehicles. The simulator is composed of two layers, one layer simulating the physical activities taking place in the transport chain, e.g., production, storage, and transports of goods, and another layer simulating the different actors’ decision making processes. The decision layer is implemented by a multi-agent system where each agent corresponds to a particular actor and models the way it acts in different situations. The simulator will be used for analyzing the costs and environmental effects, and will in this way provide guidance in decision making regarding control policies. In addition, it will be possible for companies to use the simulator in order to determine cost-effective strategies given different (future) scenarios.
multi agent systems and agent based simulation | 2009
Lawrence Henesey; Paul Davidsson; Jan A. Persson
Due to globalization and the growth of international trade, many container terminals are trying to improve performance in order to keep up with demand. One technology that has been proposed is the use of Automated Guided Vehicles (AGVs) in the handling of containers within terminals. Recently, a new generation of AGVs has been developed which makes use of cassettes that can be detached from the AGV. We have developed an agent-based simulator for evaluating the cassette-based system and comparing it to a more traditional AGV system. In addition, a number of different configurations of container terminal equipment, e.g., number of AGVs and cassettes, have been studied in order to find the most efficient configuration. The simulation results suggest that there are configurations in which the cassette-based system is more cost efficient than a traditional AGV system, as well as confirming that multi agent based simulation is a promising approach to this type of applications.
multiagent system technologies | 2006
Lawrence Henesey; Paul Davidsson; Jan A. Persson
An agent based simulator for evaluating operational policies in the transshipment of containers in a container terminal is described. The simulation tool, called SimPort, is a decentralized approach to simulating managers and entities in a container terminal. We use real data from a container terminal, for evaluating eight transshipment policies. The simulation results indicate that good choices of yard stacking and berthing position polices can lead to faster ship turn-around times, for instance, the Overall Time Shortening policy offers a lower cost and when combined with a Shortest Job First sequencing of arriving ships on average yielded a faster ship turn around time. The results also indicated, with respect to the studied performance measures that Stacking by Destination is a good choice of policy.
hawaii international conference on system sciences | 2005
Jan A. Persson; Paul Davidsson
In this research project, an integration of multi-agent technology and optimization techniques is suggested for the combined production and transport planning problem in a transport chain. The chain consists of a producer, a transport operator, and a number of customers. Optimization decomposition techniques use (dual) prices of resources to coordinate the generation of different plans in the so called sub-problems. We argue that these dual prices and generated plans can enhance the multi-agent based approach. By using the agent technology, we can better resemble the interactions between real planners reallocating resources. A transport chain within the food industry has been selected for validating the developed solution method.
Procedia Computer Science | 2013
Johan Holmgren; Mattias Dahl; Paul Davidsson; Jan A. Persson
The 4th International Conference on Ambient Systems, Networks and Technologies, June 25-28, 2013, Halifax, Nova Scotia, Canada
International Journal of Production Research | 2004
Jan A. Persson; Maud Göthe-Lundgren; Jan T. Lundgren; Bernard Gendron
In this paper we present a tabu search heuristic which can be used for scheduling the production at an oil refinery. The scheduling problem is to decide which production modes to use at the different processing units at each point in time. The problem is a type of lot-sizing problem where costs of changeovers, inventories and production are considered. In the suggested tabu search heuristic we explore the use of variable neighbourhood, dynamic penalty and different tabu lists. Computational results are presented for different versions of the heuristic and the results are compared to the best-known lower bound for a set of scheduling scenarios.