René Victor Valqui Vidal

Applied Simulated annealing

1. Problem Independent Distributed Simulated Annealing and its Applications.- 2. On Simulating Thermodynamics.- 3. Solving the Quadratic Assignment Problem.- 4. A Computational Comparison of Simulated Annealing and Tabu Search Applied to the Quadratic Assignment Problem.- 5. School Timetables: A Case Study in Simulated Annealing.- 6. Using Simulated Annealing for Efficient Allocation of Students to Practical Classes.- 7. Timetabling by Simulated Annealing.- 8. Using Simulated Annealing to Solve Concentrator Location Problems in Telecommunication Networks.- 9. Design of a Teleprocessing Communication Network Using Simulated Annealing.- 10. Location of Civil Defence Sirens.- 11. Solving the Afforestation Problem.- 12. Algorithms for Nesting Problems.- 13. Balanced Grouping through Simulated Annealing.- 14. Optimal Partition of an Interval - The Discrete Version.- 15. Simulated Annealing in Image Processing.- 16. Optimal Pallet Capacity for a FMS.- 17. Final Remarks.

Booking policy for flights with two types of passengers

Abstract An overbooking model for a fixed nonstop flight with two types of passengers is presented. The model takes cancellations, and reservations prior to departure into consideration as well as ‘no-shows’ (passengers who fail to arrive for flights without notice), denied boardings and downgrading of passengers. The model treats the airline booking process as a Markovian nonhomogeneous sequential decision process. The model is solved by two dimensional stochastic dynamic programming. Computational experiences and numerical results from a real-life case, including different types of sensivity analysis, are presented.

Using soft OR in a small company--The case of Kirby

High demands are placed on traditional small companies to make technological adaptations and push forward global digital markets. For small companies, this is not a simple task: they lack knowledge about the technology options and on strategic management of information technology (IT). This paper discusses the practical experiences of applying soft OR methodologies to a small company facing this complex situation. Applications of SWOT analysis and the strategic choice approach were made in the company for evaluation of such methodological support to a small companys learning process. It is concluded that soft OR can be an important factor for developing IT strategic management in small companies. � 2003 Published by Elsevier B.V.

Inter-process synchronization in steel production

SUMMARY The development of strategies for sequencing slabs through the reheat furnace and rolling mill of a modern steel production facility is complicated by multiple, and often conflicting production objectives. Optimal energy efficiency through the reheat furnace may lead to inefficient rolling sequences or less than desirable product delivery schedules. Not only is model formulation complicated, but the combinatorial nature of the problem precludes optimal solution. A heuristic procedure for solving this multi-objective product sequencing problem has been developed and tested under production conditions in a Danish steel mill. The methodology, which is based on a modified ‘greedy’ algorithm is presented and results using actual production data are discussed

The discrete-time maximum principle : a survey and some new results

In this paper we present a review of the development of the discrete maximum principle. In the presentation, the emphasis is on a geometrical interpretation. The crucial assumptions in the theory developed are pointed out, and the attempts to overcome the limitation in the resulting theorems ore exposed. Following the review, we present a new approach to optimization of the multi-stage optimization problems called the ’ upper boundary approach ’. The classical methods of solving this problem are shown to fit smoothly into the new approach. Moreover, using this approach a number of new results have been developed, among these a new generalized version of the discrete maximum principle. The new version does not require the assumption of directional convexity.

Community facilitation of problem structuring and decision making processes: Experiences from the EU LEADER+ programme

This paper reports on the work carried out supporting a rural community in Denmark under the LEADER+ programme. This is a programme that supports development in particularly vulnerable rural regions of the European countries members of EU. It supports creative and innovative projects that can contribute to long-term and sustainable development in these regions. The main tasks have been the organisation and facilitation of conferences and workshops to structure the problematic situation of identifying and designing innovative projects for the development of the community and to support decision making processes related to the agreement on action plans. Learning to design, plan, manage and facilitate conferences and workshops have also being another central activity. The main purpose of these conferences and workshops was not only problem structuring and decision making in connection with community development but also the transfer of facilitation skills and appropriate methods to the community.

Creativity for problem solvers

This paper presents some modern and interdisciplinary concepts about creativity and creative processes specially related to problem solving. Central publications related to the theme are briefly reviewed. Creative tools and approaches suitable to support problem solving are also presented. Finally, the paper outlines the author’s experiences using creative tools and approaches to: Facilitation of problem solving processes, strategy development in organisations, design of optimisation systems for large scale and complex logistic systems, and creative design of software optimisation for complex non-linear systems.

A Simple Method to Solve Some Simple Allocation Problems

Abstract The paper discusses a classical resource allocation problem. Using elementary arguments on Lagrangian duality it is shown that this problem can be reduced to a single one-dimensional maximization of a differentiable concave function. Moreover, a simple graphical method is developed and applied to a family of well-known problems from the literature.

A graphical method to solve a family of allocation problems

Abstract This paper discusses the classical resource allocation problem. By very elementary arguments on Lagrangian duality it is shown that this problem can be reduced to a single one-dimensional maximization of a differentiable concave function. Moreover, a simple graphical method is developed and applied to a family of well-known problems from the literature.

Planning of high school examinations in Denmark

Abstract This paper presents a computer based support system used to plan high school examinations in Denmark. We will discuss the methods and techniques used to solve such a complex and large scale combinatorial problem. Decomposition and other heuristic principles have been used extensively to develop a clear user-friendly and robust approach. The system has been implemented by the Danish Ministry of Education and has been used successfully for the last three years. We will also present some practical experiences.