Said Salhi

Discrete location theory

Ingredients of Locational Analysis (J. Krarup & P. Pruzan). The p-Median Problem and Generalizations (P. Mirchandani). The Uncapacitated Facility Location Problem (G. Cornuejols, et al.). Multiperiod Capacitated Location Models (S. Jacobsen). Decomposition Methods for Facility Location Problems (T. Magnanti & R. Wong). Covering Problems (A. Kolen & A. Tamir). p-Center Problems (G. Handler). Duality: Covering and Constraining p-Center Problems on Trees (B. Tansel, et al.). Locations with Spatial Interactions: The Quadratic Assignment Problem (R. Burkard). Locations with Spatial Interactions: Competitive Locations and Games (S. Hakimi). Equilibrium Analysis for Voting and Competitive Location Problems (P. Hansen, et al.). Location of Mobile Units in a Stochastic Environment (O. Berman, et al.). Index.

Inventory routing problems: a logistical overview

This paper presents an overview of Supply Chain Management while focussing on the area of Inventory Routing. We aim to provide the state-of-the-art in this area while highlighting the usefulness of the models in practice as well as their limitations. We have classified the papers based on the planning horizon employed in the models namely single period, multiperiod and infinite horizon models that are then complemented by those with stochastic demand patterns. Future research avenues that we believe to be of interest to the OR/MS community are also presented.

A multi-level composite heuristic for the multi-depot vehicle fleet mix problem

The problem of simultaneously allocating customers to depots, finding the delivery routes and determining the vehicle fleet composition is addressed. A multi-level composite heuristic is proposed and two reduction tests are designed to enhance its efficiency. The proposed heuristic is tested on benchmark problems involving up to 360 customers, 2 to 9 depots and 5 different vehicle capacities. When tested on the special case, the multi-depot vehicle routing, our heuristic yields solutions almost as good as those found by the best known heuristics but using only 5 to 10% of their computing time. Encouraging results were also obtained for the case where the vehicles have different capacities.

Incorporating vehicle routing into the vehicle fleet composition problem

An efficient heuristic for determining the composition of a vehicle fleet is developed which considers delivery routes whilst evaluating fleet mixes. The aim is to include a perturbation procedure within existing or constructed routes to reduce the total cost of routing and acquisition by improving the utilisation of the vehicles. This approach has been tested on twenty problems given in the literature and new best results are reported here. An extensive literature review is also given.

Solving the multiple competitive facilities location problem

In this paper we propose five heuristic procedures for the solution of the multiple competitive facilities location problem. A franchise of several facilities is to be located in a trade area where competing facilities already exist. The objective is to maximize the market share captured by the franchise as a whole. We perform extensive computational tests and conclude that a two-step heuristic procedure combining simulated annealing and an ascent algorithm provides the best solutions.

A variable neighborhood-based heuristic for the heterogeneous fleet vehicle routing problem

The heterogeneous fleet vehicle routing problem is investigated using some adaptations of the variable neighborhood search (VNS). The initial solution is obtained by Dijkstras algorithm based on a cost network constructed by the sweep algorithm and the 2-opt. Our VNS algorithm uses several neighborhoods which are adapted for this problem. In addition, a number of local search methods together with a diversification procedure are used. Two VNS variants, which differ in the order the diversification and Dijkstras algorithm are used, are implemented. Both variants appear to be competitive and produce new best results when tested on the data sets from the literature. We also constructed larger data sets for which benchmarking results are provided for future comparison.

A multi-phase constructive heuristic for the vehicle routing problem with multiple trips

An extension to the classical vehicle routing problem where vehicles can be assigned more than one route within a working time period is investigated. A multi-phase constructive heuristic, which is enhanced by suitable data structure, is proposed. Results are given comparing to benchmarks from the literature.

A Tabu Search Approach for the Resource ConstrainedProject Scheduling Problem

An appropriate tabu search implementation is designed to solve the resource constrained project scheduling problem. This approach uses well defined move strategies and a structured neighbourhood, defines appropriate tabu status and tenure and takes account of objective function approximation to speed up the search process. A sound understanding of the problem has helped in many ways in designing and enhancing the tabu search methodology. The method uses diversification, intensification and handles infeasibility via strategic oscillation.The above methodology is tested on existing problems from the literature and also on parametrically generated problems with encouraging results. For comparison of results, optimal solutions are used in the former and lower bounds obtained by Lagrangian heuristics are used in the latter.

Handbook of Metaheuristics (2nd edition)

Only for you today! Discover your favourite handbook of metaheuristics 2nd edition book right here by downloading and getting the soft file of the book. This is not your time to traditionally go to the book stores to buy a book. Here, varieties of book collections are available to download. One of them is this handbook of metaheuristics 2nd edition as your preferred book. Getting this book b on-line in this site can be realized now by visiting the link page to download. It will be easy. Why should be here?

A GA Based Heuristic for the Vehicle Routing Problem with Multiple Trips

A variant of the classical vehicle routing problem, where vehicles can be assigned to more than one route within a working time period, is investigated. A hybrid Genetic Algorithm, which uses a new non-binary chromosome representation and which is enhanced by a domain specific data structure, appropriate genetic operators and a scheme for chromosome evaluation, is proposed. Test problems from the literature are used to evaluate the performance of the proposed heuristic. Encouraging results are obtained.