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Supervised learning techniques are widely employed in credit card fraud detection, as they make use of the assumption that fraudulent patterns can be learned from an analysis of past transactions. The task becomes challenging, however, when it has to take account of changes in customer behavior and fraudsters’ ability to invent novel fraud patterns. In this context, unsupervised learning techniques can help the fraud detection systems to find anomalies. In this paper we present a hybrid technique that combines supervised and unsupervised techniques to improve the fraud detection accuracy. Unsupervised outlier scores, computed at different levels of granularity, are compared and tested on a real, annotated, credit card fraud detection dataset. Experimental results show that the combination is efficient and does indeed improve the accuracy of the detection., SCOPUS: ar.j, info:eu-repo/semantics/published

The line graph of a graph G has one node per each edge of G, two of them being adjacent only when the corresponding edges have a node of G in common. In this work, we consider the problem of finding the minimum number of edges to delete so that the resulting graph is a line graph, which presents an interesting application in haplotyping of diploid organisms. We propose an Integer Linear Programming formulation for this problem. We compare our approach with the only other existing formulation for the problem and explore the possibility of combining both of them. Finally, we present a computational study to compare the different approaches proposed., SCOPUS: ar.j, info:eu-repo/semantics/published

International audience; Several algorithms for finding a lower bound on the makespan for the Resource Constrained Project Scheduling Problem (RCPSP) were proposed in the literature. However, fast computable lower bounds usually do not provide the best estimations and the methods that obtain better bounds are mainly based on the cooperation between linear and constraint programming and therefore are time-consuming. In this paper, a new pseudo-polynomial algorithm is proposed to find a makespan lower bound for RCPSP with time-dependent resource capacities. Its idea is based on a consecutive evaluation of pairs of resources and their cumulated workload. Using the proposed algorithm, several bounds for the PSPLIB benchmark were improved. The results for industrial applications are also presented where the algorithm could provide good bounds even for very large problem instances.

Reverse supply chains (RSC) deal with End-Of-Life products (EOL). They provide the benefits of reducing solid waste, creating new jobs, and generating income from the sales of re-manufactured products and savings in raw materials. At the same time, their design is more challenging in comparison with forward supply chains because of hardly predictable reverse flows of EOL products. Conventional approaches to address the uncertainty are usually risk-oriented and do not consider eventual opportunities. In order to overcome this drawback, we propose to use the R* criterion in the decision making process in a context of complete ignorance with a discrete set of equally possible scenarios. This criterion integrated in a new lexicographic algorithm is used in order to take the Decision-Maker’s (DM) behavior into account in different ways regarding if the uncertainty is considered as a risk or as an opportunity. Its performances are evaluated on the case study of facility location problem in reverse logistics.

We propose a nonparametric methodology for intertemporal production analysis that accounts for durable as well as storable inputs. Durable inputs contribute to the production outputs in multiple consecutive periods. Storable inputs are non-durable and can be stored in inventories for use in future periods. We explicitly model the possibility that firms use several vintages of the durable inputs, i.e. they invest in new durables and scrap older durables over time. Furthermore, we allow for production delays of durable inputs and storage costs for storable inputs. We characterize production behavior that is dynamically cost efficient, which allows us to evaluate the efficiency of observed production decisions. For cost inefficient behavior, we propose a measure to quantify the degree of inefficiency. An attractive feature of this measure is that it can be decomposed in period-specific cost inefficiencies. We demonstrate the usefulness of our methodology through an application to the Italian manufacturing sector of fabricated metal products over the period 1995–2007 drawn from the AMADEUS dataset., SCOPUS: ar.j, info:eu-repo/semantics/published

This paper proposes a novel framework to support the generation of strategies for multi-criteria long-term improvement. It can be applied to general preference models but it is illustrated in this article on a Multi-Attribute Value Theory model. The novel contributions to the literature are twofold. Firstly, the framework addresses the issue of resistance to change that may arise during the implementation of a strategy. It constrains a step of improvement to be focused on a single criterion, and minimizes the intensity of operational changes. Secondly, it addresses the realism of the improvement scenarios by treating three types of structural dependencies differently: the positive synergies, the negative synergies and the bottlenecks. The scenarios are generated by finding a set of efficient solutions to a shortest path problem in a graph whose edges represent possible steps of improvement. Each edge is characterized by an increase of rank or level and two penalty functions relating to the difficulty of its execution, one representing a risk associated to bottleneck mechanisms and the other to operational change relative to a previous edge. A case-study using the Shanghai Academic Ranking of World Universities is presented in order to illustrate how this framework could be useful to generate a sequence of strategic actions for the Universite libre de Bruxelles.

National audience; Contexte : 5ème cancer en termes d'incidence en France, le cancer des voies aérodigestives supérieures (VADS) impacte de façon importante la vie quotidienne des sujets atteints, tant en termes d'activités que de participation. Il devient donc nécessaire d'évaluer au préalable les dimensions fonctionnelles et psychosociales : nous avons ainsi développé le Carcinologic Handicap Index (ou CHI). Objectif(s) : Cette étude prospective a pour objet l'élaboration et la validation d'un questionnaire d'autoévaluation du handicap après traitement des cancers des VADS. Méthode : Le CHI a été conçu de façon empirique sur le modèle du « Voice handicap index ». Il comprend 9 dimensions autoévaluées par le patient (douleur, déglutition, nutrition, respiration, phonation, audition, vision, olfaction-gustation, psychosocial). Chacune comporte 4 questions à coter en termes de fréquence, ce qui permet le calcul d'un score pour chaque dimension ainsi qu'un score global. Il a été testé auprès de 86 patients constituant la population pathologique (majorité d'hommes, âge moyen de 59 ans, présentant une tumeur des voies aérodigestives supérieures) et 18 sujets (population témoin), pour validation du questionnaire. Résultats : La cohérence interne globale est à 0,905 (test alpha de Cronbach). La validité de contenu (r, entre les scores du questionnaire et les EVA correspondantes) se situe entre 0,6 et 0,8 sauf pour le domaine Vision et pour le score total par rapport à l'EVA de la santé générale (r ¿ 0,5), la pathologie n'altérant pas directement la vision et n'étant qu'un élément parmi d'autre pouvant jouer sur la santé générale). La validité temporelle est satisfaisante (r > 0,7 avec p < 0,0001) sauf pour le domaine Respiration (r = 0,624, pouvant s'expliquer par la fluctuation de l'encombrement pulmonaire). Selon le site de la lésion, les domaines Déglutition, Nutrition et Respiration sont impactés différemment. Enfin, nous ne retrouvons pas de différence significative entre patients et témoins pour les domaines Douleur, Audition et Vision. Discussion : Le CHI présente des qualités psychométriques acceptables et peut être considéré comme un véritable outil clinique destiné aux professionnels de santé permettant de prendre en compte l'impact de la pathologie ORL sur la qualité de vie des patients, principalement concernant les domaines fonctionnels directement atteints par le cancer ou son traitement. http://congresccfuo.fr/

The aircraft maintenance processes play an important role in a safe operation of an aircraft. Maintenance services organizations take responsibility for the maintenance process and approve the airworthiness of an aircraft after undertaking the maintenance activities. International law determines the quality of aircraft maintenance processes by setting requirements concerning, among other, a quality management system, a safety management system and operators’ competences. As a consequence of the rising number of aircraft in operation, the volume of maintenance activities grows. However, the customers increasingly pose requirements concerning the minimization of the maintenance service lead time. In order to remain competitive, the maintenance service organizations have to reduce the lead time of their services. However, this objective in not easy to attain, since the complexity of aircraft maintenance operations require specific skills and pose a number of organisational and technical constraints to be respected during the maintenance process. In the paper, a mathematical programming model is developed in order to help decision makers in managing the operators’ skills during the operators assignment to the activities to be performed. In particular, the Hall’s marriage theorem is used to formalise complex restrictions of operators assignment to maintenance activities. The objective of the optimization problem is to minimize total makespan time. The model is applied to a case study.

Assigning aircraft to gates is an important decision problem that airport professionals face every day. The solution of this problem has raised a significant research effort and many variants of this problem have been studied. In this paper, we review past work with a focus on identifying types of formulations, classifying objectives, and categorising solution methods. The review indicates that there is no standard formulation, that passenger oriented objectives are most common, and that more recent work are multi-objective. In terms of solution methods, heuristic and metaheuristic approaches are dominant which provides an opportunity to develop exact and approximate approaches both for the single and multi-objective problems., SCOPUS: re.j, info:eu-repo/semantics/published

This paper presents a new, carefully designed algorithm for five bi-objective permutation flow shop scheduling problems that arise from the pairwise combinations of the objectives (i) makespan, (ii) the sum of the completion times of the jobs, and (iii) both, the weighted and non-weighted total tardiness of all jobs. The proposed algorithm combines two search methods, two-phase local search and Pareto local search, which are representative of two different, but complementary, paradigms for multi-objective optimization in terms of Pareto-optimality. The design of the hybrid algorithm is based on a careful experimental analysis of crucial algorithmic components of these two search methods. We compared our algorithm to the two best algorithms identified, among a set of 23 candidate algorithms, in a recent review of the bi-objective permutation flow-shop scheduling problem. We have reimplemented carefully these two algorithms in order to assess the quality of our algorithm. The experimental comparison in this paper shows that the proposed algorithm obtains results that often dominate the output of the two best algorithms from the literature. Therefore, our analysis shows without ambiguity that the proposed algorithm is a new state-of-the-art algorithm for the bi-objective permutation flow-shop problems studied in this paper. © 2010 Elsevier Ltd. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

Cross-country price discrimination in an oligopolistic setting is examined in the context of the market for cars in the European Community. Two types of regulation aimed at limiting price discrimination are considered: in one constraints are imposed on absolute cross-country price differentials, in the other constraints are imposed on price ratios. The first rule turns out to be uniformly better than the second in a way that we make precise. When a country with no domestic producer of cars is introduced, it seems that the redistributional effects of antidiscrimination regulation may be more important than any possible gains in efficiency, info:eu-repo/semantics/published