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
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,...
How to locate intermodal terminals for achieving economic and environmental competitiveness? - Mostert, Martine; Limbourg, Sabine
Europe has a strong commitment to the development of competitive and sustainable transportation. An intermediate objective cited in the “White Paper” is to shift 30% of 300 km and above road freight transportation to more environmentally-friendly modes of transport such as rail and water by 2030. Improving and expanding the intermodal network is one way to achieve this goal. However, intermodal transport requires intermodal terminals where the transfer from one mode to another can occur. The location of those terminals is of strategic importance for the competitiveness of intermodal transport. The objective of this paper is therefore to develop a...
Logistics hub: the case of Liège - Limbourg, Sabine; Mostert, Martine; Paquay, Célia
A logistics hub can be defined as a specific area where all the activities relating to transport, logistics and goods distribution are carried out. With its central location in Europe, highly developed infrastructures, airport and inland terminals, the region of Liège claims to be a logistics hub. This paper applies a strategic decision model based on seven relevant criteria (infrastructure, proximity to market, land availability, government and industry support, labour supply, origin/destination distances and congestion) to assess the efficiency of the logistics hub of the region of Liège. Two SWOT analyses are performed in parallel to evaluate the positions of...
A 'price balance statistic' for optimizing pricing strategies: a better estimation of elasticities and cross-elasticities - Lurkin, Virginie; Schyns, Michael; Garrow, Laurie A.; Jacobs, Timothy L.
Demand forecasting, price optimization and capacity controls form three major tools of revenue management. Over the past few decades, each discipline has generated a great deal of research but has typically been studied separately from the others. Yet, better understanding their relationship gives an airline the opportunity to increase its profitability. In prior work, Tim Jacobs and colleagues introduced a macro-level metric known as the ‘Price Balance Statistic (PBS)’ for evaluating the quality of a given pricing strategy and guiding a search algorithm to identify an optimal alignment between pricing structure, scheduled capacity and RM controls using marginal revenue principles....
An Ant Colony System for Responsive Dynamic Vehicle Routing - Schyns, Michael
We present an algorithm based on an Ant Colony System to deal with a broad
range of Dynamic Capacitated Vehicle Routing Problems with Time Windows, (partial)
Split Delivery and Heterogeneous fleets (DVRPTWSD). Besides the traditional distance
criterion, we address the important case of responsiveness. Responsiveness is defined here
as completing a delivery as soon as possible, within the time window, such that the client or
the truck may restart its activities. This is crucial for many production or service activities
in different fields: express parcel deliveries, taxi services, Just in Time production, express
repair services, medical care, petrol station replenishment, etc. We develop an interactive
web-based solution to...