A new stochastic Petri net model and its applications to logistics systems

This is a summary of the author’s PhD thesis supervised by Lionel Amodeo and Hoaxun Chen and defended on 29 November 2005 at the Université de Technologie de Troyes (France). The thesis is written in French and is available from the author upon request. This work deals with a new stochastic Petri net model and its applications for modeling and studying logistics systems and more generally discrete event dynamic systems.      

Approximation and resolution of min–max and min–max regret versions of combinatorial optimization problems

This is a summary of the most important results presented in the author’s PhD thesis. This thesis, written in French, was defended on November 2005 and supervised by Cristina Bazgan and Daniel Vanderpooten. A copy is available from the author upon request. This thesis deals with the complexity, approximation and resolution of the min–max and min–max versions of classical combinatorial optimization problems. In addition to these theoretical aspects, a practical application of robustness approaches to the problem of data association is considered.     

A framework for robust and flexible optimisation using metaheuristics

This is a summary of the most important results presented in the authors PhD thesis. This thesis, written in English, was defended on 13 June 2003 and supervised by Johan Springael and Gerrit K. Janssens. A copy is available from the author upon request. This PhD thesis focuses on stochastic problems and develops a framework to find robust and flexible solutions of such problems. The framework is applied to several well-known problems in the realm of supply chain design. Besides this framework, the thesis contains several other important contributions. A new type of robustness and flexibility is proposed, that expresses the need for solutions to remain approximately the same when changes occur in the problem data. Several distance measures are developed to calculate the distance (or similarity) between solutions of different permutation type problems. A new type of genetic algorithm is also proposed, that uses a distance measure to maintain a diverse population of high-quality solutions.Received: June 2003     

Multicast problems in telecommunication networks

This is a summary of the author’s PhD thesis supervised by Paolo Nobili and defended on 20 April 2007 at the Università del Salento (Lecce). The thesis is written in English and is available from the author upon request. This work deals with multicast problems in wireless Ad-Hoc networks and some related variants.      

Nonsmooth optimization: theory and algorithms

This is a summary of the author’s PhD thesis supervised by Manlio Gaudioso and Maria Flavia Monaco and defended on 21 February 2008 at the Università della Calabria. The thesis is a survey on nonsmooth optimization methods for both convex and nonconvex functions. The main contribution of the dissertation is the presentation of a new bundle type method. The thesis is written in English and is available from .     

Exact and heuristic algorithms for routing problems

This is a summary of the authors PhD thesis supervised by Daniele Vigo and defended on 30 March 2010, at the Università di Bologna. The thesis is written in English and is available from the author upon request. Several rich routing problems attaining to the transportation area have been studied. “Simple” algorithms have been proposed to solve them, both exact and heuristic, producing high quality solutions and transferrable methods.     

A method for determining cost-efficient inspection strategies in multistage production systems

This is a summary of the author’s PhD thesis. The thesis, written in English, was defended on 6 March 2006, and was supervised by Rik Van Landeghem and Claude Van Mechelen. A copy is available from the author upon request. This PhD thesis focuses on (cost-)efficient quality control for multistage production processes, a major issue to manufacturers. Subjecting a larger product fraction to inspection, or tightening the acceptance limits, will normally lead to a higher product quality, but will also result in higher costs of inspection, scrap and rework. Quantifying this trade-off and thus establishing ways of finding an economic optimum is at the heart of this research. Thereto, a metaheuristic solution approach, consisting of an evolutionary algorithm combined with simulation, is presented and validated.      

Optimization via simulation for logistic systems planning and control

This text summarizes the author’s PhD thesis, presented in February 2007 at the University of Calabria and supervised by Roberto Musmanno and Pasquale Legato. The work deals with the field of optimization via simulation. A special emphasis is put on problems with discrete decision variables because they are especially relevant in engineering applications (e.g., in the design of logistic systems). In particular, the thesis focuses on a critical decision problem at marine container terminals. For tackling the problem, an optimization via simulation procedure is presented. Computational results are obtained by using high performance computing systems. The thesis is written in Italian and is available from the author upon request.      

Exact methods for combinatorial auctions

This is a summary of the author’s PhD thesis supervised by Frits Spieksma and defended on 20 December 2006 at the Katholieke Universiteit Leuven. The thesis is written in English and is available from the author’s website (http://www.econ.kuleuven.be/dries.goossens/public). This work deals with combinatorial auctions, i.e., auctions where bidders can bid on sets of items. We study two special cases, namely the total quantity discount auction and the matrix bid auction.      

Models and algorithms for the reconfiguration of distributed wireless switching systems

This paper is a summary of the author’s PhD thesis entitled “Models and algorithms for the reconfiguration of wireless switching systems”. The thesis deals with the study of a strongly NP-hard resource-constrained scheduling problem arising from the telecommunication industry. This work was supervised by Jacques Carlier and Dritan Nace, both from Université de Technologie de Compiègne, and carried out while the author was a System Architect within Nortel GSM Access R&D organization. The thesis, which is written in both French and English, has been defended on 29 March 2007 and is available by email request to the author. This research was supported in part by Association Nationale de la Recherche Technique grant CIFRE-121/2004.     

Algorithms for some graph theoretical optimization problems

This is a summary of the main results presented in the author’s PhD thesis. This thesis, written in English, was supervised by Frits Spieksma and defended on September 23, 2005 at the Katholieke Universiteit Leuven. A copy of the thesis is available from the authors website (http://www.econ. kuleuven.be/linda.moonen/public/). The thesis can be roughly split into two parts. The first part is dedicated to the problem of partitioning partially ordered sets into chains of limited size. The second part deals with the structure and the connectivity of the Internet.     

New models and algorithms for the cyclic inventory routing problem

This is a summary of the author’s PhD thesis supervised by El-Houssaine Aghezzaf and defended on 4 December 2006 at the Universiteit Gent. The thesis is written in English and is electronically available from http://ir18.ugent.be/birger.raa/. This work studies the problem of finding optimal three-way cost trade-offs between vehicle fleet costs, distribution costs and holding costs in the cyclic replenishment of a set of customers with constant demand rates from a single depot.      

On a new class of nonlinear set covering problems arising in wireless network design

This is a summary of the author’s PhD thesis, supervised by Edoardo Amaldi and defended on 28 April 2006 at Politecnico di Milano, Dipartimento di Matematica. The thesis is written in English and is available from the author upon request. The thesis investigates a class of nonlinear set covering variants arising from the problem of designing single-frequency Wireless Local Area Networks (WLANs) with maximum efficiency. In the first part of the thesis a basic hyperbolic formulation of the problem is considered. After a complexity and approximability study, the problem is tackled by linearization techniques, and by Lagrangean and Dantzig–Wolfe decompositions. The second part of the thesis focuses on variants accounting for various relevant features of the WLAN application. A Branch-and-Price algorithm is presented, and extensions to the multiple-frequency WLAN design problem are considered.      

Multiple criteria decision aiding: a dialectical perspective

This is a summary of the Ouerdane’s PhD thesis supervised by Alexis Tsoukiàs and Nicolas Maudet and defended on 01 December 2009 at the Université Paris-Dauphine, Paris. The thesis is written in English and is available from the author upon request. This work has the aim to investigate the different ways to use argumentation theory in a decision context. More precisely within multi-criteria evaluation models. The principal aim is to meet the needs in terms of explanations and revision during a decision process.     

Enhanced mixed integer programming techniques and routing problems

This is a summary of the author’s PhD thesis supervised by Andrea Lodi and Paolo Toth and defended on 16 April 2009 at the Università di Bologna. The thesis is written in English and is available from the author upon request. This work is focused on Mixed Integer Programming (MIP). In particular, the first part of the thesis deals with general purpose cutting planes, which are probably the key ingredient behind the success of the current generation of MIP solvers. The second part is instead focused on the heuristic and exact exploitation of integer programming techniques for hard combinatorial optimization problems in the context of routing applications.     

Polynomial approximation: a structural and operational study

This is a summary of the most important results of the author’s PhD thesis. This thesis, supervised by Vangelis Th. Paschos, was defended in October 2005 at the Université Paris Dauphine. It is written in French and is available on-line. The thesis is focused on combinatorial optimization problems, studied from the standpoint of polynomial approximation theory. We were interested both in structural concerns (mainly completeness in approximation classes and logical expressivity) and operational ones (with the study of satisfiability, coloring and covering problems). http://www.lamsade.dauphine.fr/~escoffier/fichiers/TheseEscoffier.pdf     

Multidimensional Lipschitz global optimization based on efficient diagonal partitions

This is a summary of the author’s PhD thesis, supervised by Yaroslav D. Sergeyev and defended on May 5, 2006, at the University of Rome “La Sapienza”. The thesis is written in English and is available from the author upon request. In this work, the global optimization problem of a multidimensional “black-box” function satisfying the Lipschitz condition over a hyperinterval with an unknown Lipschitz constant is considered. The objective function is assumed hard to evaluate. A new efficient diagonal scheme for constructing fast algorithms for solving this problem is examined and illustrated by developing several powerful global optimization methods. A deep theoretical study is performed which highlights the benefit of the approach introduced over traditionally used diagonal algorithms. Theoretical conclusions are confirmed by results of extensive numerical experiments.      

A multicriteria perspective on reverse auctions

This is a summary of the main contributions of the author’s PhD thesis. The thesis is written in English. It was supervised by Philippe Vincke and was defended on 20 December 2005 at the Université Libre de Bruxelles. A copy is available from the author upon request. The aim of this work is to investigate the use of a partial relations for bids’ comparisons in the context of multi-attribute auctions. At first a theoretical framework is developed. Then a specific model referred to as the butterfly model is presented. Finally the concept of bidding niches is formalized and related to the aforementioned model.      

Exact and approximate resolution of integral multiflow and multicut problems: algorithms and complexity

This is a summary of the author’s PhD thesis supervised by Marie- Christine Costa and Frédéric Roupin and defended on 20 November 2006 at the Conservatoire National des Arts et Métiers in Paris (France). The thesis is written in French and is available upon request from the author. This work deals with two well-known optimization problems from graph theory: the maximum integral multiflow and the minimum multicut problems. The main contributions of this thesis concern the polynomial-time solvability and the approximation of these two problems (and of some of their variants) in classical classes of graphs: bounded tree-width graphs, planar graphs and grids, digraphs, etc.      

A decomposition-based solution method for stochastic mixed integer nonlinear programs

This is a summary of the main results presented in the author’s PhD thesis, supervised by D. Conforti and P. Beraldi and defended on March 2005. The thesis, written in English, is available from the author upon request. It describes one of the very few existing implementations of a method for solving stochastic mixed integer nonlinear programming problems based on deterministic global optimization. In order to face the computational challenge involved in the solution of such multi-scenario nonconvex problems, a branch and bound approach is proposed that exploits the peculiar structure of stochastic programming problem.