Avoiding congestion in freight transport planning: a case study in Flanders

Conference (2011)

A substantial increase in transport intensity for passenger and freight traffic has been observed during the last decades and research confirms that this trend will continue in the years to come. Economic ... [more ▼]

A substantial increase in transport intensity for passenger and freight traffic has been observed during the last decades and research confirms that this trend will continue in the years to come. Economic centres have turned into heavily congested areas. The freight transport sector incurs excessive waiting times on the road as well as at intermediate stops (e.g. sea terminals, loading or unloading points). This may cause economic losses and environmental damages. Waiting times may be avoided by taking into account congestion in freight transport planning. Vehicle routing problems arise when several pickup and delivery operations need to be performed, mainly by truck, over relatively short distances [1]. Congestion leads to uncertain travel times on links and uncertain waiting times at pickup or delivery locations. Peak hours may be avoided on congested road segments by changing the order in which customers are served. On the other hand, time slots at customer sites may be renegotiated, creating more flexibility to avoid congestion on the road and at customer stops. The objective of this paper is to estimate the benefits of taking congestion into account in transport planning and to quantify the impact of delivery restrictions on transport costs. A highly congested road network raises the need for robust vehicle routing decisions. Current traffic conditions give rise to uncertain travel times. The reliability of travel time on a route is one of the dominant factors affecting route and departure time choices in passenger transport [2]. Similarly, in freight transport the reliability of travel times may be taken into account when planning vehicle routes. In this paper congestion is modelled as time-dependent travel times. These travel times take into account the dynamics of the time lost due to congestion using the Bureau of Public Roads (BPR) function, which is commonly-used for relating travel times to increases in travel volume [3]. The Time Dependent Vehicle Routing Problem (TDVRP) will be studied as a deterministic planning problem taking into account peak hour traffic congestion. Solution methods for the TDVRP have been focused on heuristic approaches [4, 5, 6, 7]. Kok [8] applies a restricted dynamic programming heuristic to solve a TDVRP. In this paper a heuristic algorithm will be presented to solve problem instances of realistic size. Next, this algorithm will be applied to perform a sensitivity analysis to identify which congestion avoiding strategies have a large influence on the objective function. Shippers may adapt the way they plan their transport as a strategy to avoid congestion. For example, time windows at customer locations may be renegotiated, departure times at the depot may be questioned or the assignment of customers to routes and the order in which customers are served may be changed. The proposed methodology will be demonstrated with a Flemish case study. [less ▲]

Avoiding mass transfer limitations in carbon supported catalysis by using carbon xerogel type supports

Conference (2006)

Avoir le véhicule vert

Article for general public (2007)

L'argument est séduisant d'acquérir un nouveau véhicule, plus propre en émission de CO2, mais il faut aussi se débarrasser de son ancien. Attention au bilan CO2 total de l'opération ! [...] De plus en ... [more ▼]

L'argument est séduisant d'acquérir un nouveau véhicule, plus propre en émission de CO2, mais il faut aussi se débarrasser de son ancien. Attention au bilan CO2 total de l'opération ! [...] De plus en plus d'entreprises s'emparent des problématiques environnementales pour vanter leurs produits "plus écologiques". Il faut bien avouer que, suite au film d'Al Gore sur le réchauffement climatique et aux interventions très médiatisées de Nicolas Hulot sur l'urgence écologique, le sujet est très à la mode dans notre pays. D'autant plus qu'au cours des trois dernières années de divers constructeurs automobiles devenues très "vertes" nous incitent à remplacer notre ancien véhicule "polluant" par un nouveau, plus économe en carburant et donc plus propre également en émissions de CO2. Certes l'argument est séduisant. Il faut cependant prendre garde de ne pas oublier que la production, le transport, le marketing et le démantèlement d'un nouveau véhicule émettent aussi beaucoup de CO2 et doivent donc être pris en compte dans le "bilan CO2" total de l'opération. [...] [less ▲]

Les avortements d'origine bactérienne dans l'espèce canine

in Annales de Médecine Vétérinaire (1983), 127

AVPRO-LBR5, an Initial Design Software Suite with Scantling Optimization Capabilities

in IMDC’2003, Eighth International Marine Design Conference, Grèce, Edited by A. Papanikolaou (NTUA, Athènes), Vol2, May 2003 (2003, May)

Awake craniotomy

in European Journal of Anaesthesiology (2009), 26(11), 906-912

Awake craniotomy has become an increasingly frequent procedure. In this paper, the principles of its anaesthetic management are reviewed. The means allowing achievement of anaesthetic objectives are ... [more ▼]

Awake craniotomy has become an increasingly frequent procedure. In this paper, the principles of its anaesthetic management are reviewed. The means allowing achievement of anaesthetic objectives are described, with emphasis on points that determine success of the procedure. A careful and adequate selection and preparation of patients are mandatory, and the intervening team must be a skilled team. Choosing an awake technique or general anaesthesia depends on several factors, including the risk of obstructive apnoea, seizures, nausea and vomiting, patient's ability to cooperate, and localization of lesions. The main challenge of intraoperative anaesthetic management relies on the ability of rapidly adjusting the level of sedation and analgesia according to the sequence of surgical events, while ensuring haemodynamic stability, adequate ventilation, and minimal interference with eventual eletrophysiological recordings. Throughout the procedure, complications must be anticipated and managed according to predefined guidelines. More prospective randomized clinical trials are still needed to improve safety and efficacy of awake craniotomies, as well as to validate this technique in comparison with more conventional anaesthetic management. [less ▲]

Awans et Waroux: Guerre de Troie en Hesbaye ou rivalités familiales ?

Scientific conference (2011, June 16)

L'axe rénine-angiotensine-aldostérone : Le syndrome de Conn

Scientific conference (2005, January 14)

L'axe somatotrope et les productions animales. Contributions à la compréhension de certains mécanismes impliqués dans la croissance et la lactation

Thèse d’agrégation de l’enseignement supérieur (1997)

Axial dispersion in trickle-flow reactors

in Enclyclopedia of Fluid Mechanisms (1986)