ORBi Open Repository and Bibliography
In may 2007, the ULg's Administrative Board (joined in June 2007 by the FUSAGx) decided to create an institutional repository and defined a strong institutional self-archiving policy to increase the visibility, accessibility and impact of the University's publications (Board's decision).
This decision led to the official launch, in November 2008, of the ORBi platform including both the Academic Bibliography and the Institutional Repository of the Wallonia-Europe University Academy.
Business & economic sciences => Quantitative methods in economics & management
Vers un transport aérien plus écologique et plus économique - Lurkin, Virginie
de l’avion en vol.
Mieux, on peut montrer que la position du centre de gravité (qui dépend du chargement de l’avion) affecte la consommation de carburant. Ce résultat revêt une importance majeure dans un contexte d’augmentation des prix du pétrole et où il s’agit de réduire les émissions polluantes.
Pour un transport aérien plus économique, il s’agit aussi, en cas de livraisons à différents endroits, de réduire au maximum les temps de chargements et de déchargements afin de limiter les coûts liés aux paiements des salariés et à l’utilisation de chaque aéroport intermédiaire.
Au cours de mon exposé, je présente un modèle...
Integrating axle weight restrictions in a two-dimensional vehicle routing problem with sequence based loading - Pollaris, Hanne; Braekers, Kris; Caris, An; Janssens, Gerrit; Limbourg, Sabine
A mixed integer linear programming model for a two-dimensional capacitated vehicle routing problem (2L-CVRP) with sequence based loading and axle weight restrictions is provided. To the authors’ knowledge, it is the first time that axle weight restrictions are incorporated in a VRP. Axle weight limits impose a great challenge for transportation companies. Trucks with overloaded axles represent a significant threat for traffic safety and may cause serious damage to the road surface. Transporters face high fines when violating these limits. The problem is based on a real-world problem from a Belgian logistics service provider. The demand of the customers consists...
Inventory-routing problem with pickups and deliveries of RTI in closed-loop supply chain - Limbourg, Sabine
Reducing environmental impact, related regulations and potential for operational benefits are the main reasons why companies share their Returnable Transport Items (RTIs) among different partners of a closed-loop supply chain. This research deals with an inventory-routing problem with pickups and deliveries of RTIs. A mixed-integer linear program is developed and tested on small instances. To handle realistic large size problems, a clustering algorithm is coupled with a simulation model. This hybrid heuristic allows assessing the benefits of information and RTIs sharing among partners.
A constructive heuristic for the three dimensional Bin Packing Problem with transportation constraints - Paquay, Célia; Schyns, Michael; Limbourg, Sabine
The aim of this work is to propose a Relax-And-Fix heuristic to build a good initial solution to the 3D BPP. First, a mathematical formulation has been developed taking into account several types of constraints such as the stability and fragility of the boxes to pack, their possibility to rotate, the weight distribution inside the bins and their special shapes. Since this model contains a lot of integer variables, we have decided to apply the Relax-and-Fix method. We have selected several sets of variables to be the branching variables and carried out some tests.
Short Prime Quadratizations of Cubic Negative Monomials - Crama, Yves; Rodriguez Heck, Elisabeth
Pseudo-Boolean functions naturally model problems in a number of different areas such as computer science, statistics, economics, operations research or computer vision, among others. Pseudo-Boolean optimization (PBO) is NP-hard, even for quadratic polynomial objective functions. However, much progress has been done in finding exact and heuristic algorithms for the quadratic case. Quadratizations are techniques aimed at reducing a general PBO problem to a quadratic polynomial one. Quadratizing single monomials is particularly interesting because it allows quadratizing any pseudo-Boolean function by termwise quadratization. A characterization of short quadratizations for negative monomials has been provided. In this report we present a proof...
Optimization of the service start time for an elementary shortest path problem with time windows - Arda, Yasemin; Crama, Yves; Kucukaydin, Hande
We investigate an elementary shortest path problem with resource constraints
where a single capacitated vehicle, initially located at a depot, must serve
a set of customers while respecting their individual time windows. When
the vehicle visits a customer, it delivers the customer's demand and collects
a revenue in return for the delivery. The vehicle can start its trip at any
desired time. The transportation cost is a function of both the total distance
traveled and the duration of the assigned trip. The objective is to determine
the service start time from the depot, the subset of customers to be served,
and the trip to be performed so as...
A new methodological approach for error distributions selection in Finance - Hambuckers, julien; Heuchenne, Cédric
In this article, we propose a robust methodology to select the most appropriate error distribution candidate, in a classical multiplicative heteroscedastic model. In a first step, unlike to the traditional approach, we don't use any GARCH-type estimation of the conditional variance. Instead, we propose to use a recently developed nonparametric procedure (Mercurio and Spokoiny, 2004): the Local Adaptive Volatility Estimation (LAVE). The motivation for using this method is to avoid a possible model misspecification for the conditional variance. In a second step, we suggest a set of estimation and model selection procedures (Berk-Jones tests, kernel density-based selection, censored likelihood score,...