Nicolas Zufferey

Bio: Nicolas Zufferey is an academic researcher from University of Geneva. The author has contributed to research in topics: Tabu search & Metaheuristic. The author has an hindex of 23, co-authored 121 publications receiving 1949 citations. Previous affiliations of Nicolas Zufferey include Laval University & École Polytechnique Fédérale de Lausanne.

Graph colouring approaches for a satellite range scheduling problem

Abstract: A goal of this paper is to efficiently adapt the best ingredients of the graph colouring techniques to an NP-hard satellite range scheduling problem, called MuRRSP We propose two new heuristics for the MuRRSP, where as many jobs as possible have to be scheduled on several resources, while respecting time and capacity constraints In the permutation solution space, which is widely used by other researchers, a solution is represented by a permutation of the jobs, and a schedule builder is needed to generate and evaluate a feasible schedule from the permutation On the contrary, our heuristics are based on the solution space which contains all the feasible schedules Based on the similarities between the graph colouring problem and the MuRRSP, we show that the latter solution space has significant advantages A tabu search and an adaptive memory algorithms are designed to tackle the MuRRSP These heuristics are derived from efficient graph colouring methods Numerical experiments, performed on large, realistic, and challenging instances, showed that our heuristics are very competitive, robust, and outperform algorithms based on the permutation solution space

A bi-objective model for planning and managing rail-truck intermodal transportation of hazardous materials

Abstract: We propose a bi-objective optimization framework for routing rail-truck intermodal shipments with hazardous materials, when shippers and receivers have access to alternate intermodal terminals. A tabu-search based solution methodology is developed, which together with the optimization framework is applied to realistic size problem instances to gain managerial insights. Our analysis indicates that drayage accounts for a significant portion of transport risk and that it can be reduced by scheduling direct and faster trains; and, that the mix of intermodal trains depends on the interest of the decision-makers, where the resulting traffic can facilitate planning emergency response systems.

Variable Space Search for Graph Coloring

Abstract: Let G=(V,E) be a graph with vertex set V and edge set E The k-coloring problem is to assign a color (a number chosen in {1,,k}) to each vertex of G so that no edge has both endpoints with the same color We propose a new local search methodology, called Variable Space Search, which we apply to the k-coloring problem The main idea is to consider several search spaces, with various neighborhoods and objective functions, and to move from one to another when the search is blocked at a local optimum in a given search space The k-coloring problem is thus solved by combining different formulations of the problem which are not equivalent, in the sense that some constraints are possibly relaxed in one search space and always satisfied in another We show that the proposed algorithm improves on every local search used independently (ie, with a unique search space), and is competitive with the currently best coloring methods, which are complex hybrid evolutionary algorithms

Variable neighbourhood search: methods and applications

Abstract: Variable neighbourhood search (VNS) is a metaheuristic, or a framework for building heuristics, based upon systematic changes of neighbourhoods both in descent phase, to find a local minimum, and in perturbation phase to emerge from the corresponding valley It was first proposed in 1997 and has since then rapidly developed both in its methods and its applications In the present paper, these two aspects are thoroughly reviewed and an extensive bibliography is provided Moreover, one section is devoted to newcomers It consists of steps for developing a heuristic for any particular problem Those steps are common to the implementation of other metaheuristics

Project Management: A Systems Approach To Planning, Scheduling and Controlling (Book)

Abstract: PROJECT MA NA GEMENT: A SYSTEMS A PPROA CH TO PLA NNING, SCHEDULING, A ND CONTROLLING To download Project Manag ement: A Systems A pproach to Planning , Scheduling , and Controlling PDF, please access the link under and save the file or gain access to additional information which might be have conjunction with Project Management: A Systems Approach to Planning, Scheduling, and Controlling ebook.