Abstract

International audience; Because it deals with sustainably supplying cities and reducing congestion and pollution related to goods transport in urban areas, city logistics is an important field in transportation sciences. These logistics systems need to be sustainable and reliable to ensure the continued flow of goods.Logistics and Transport Modeling in Urban Goods Movement is a pivotal reference source that provides vital research on the main approaches and techniques used in urban goods transport modelling while addressing planning and management issues. Highlighting topics such as urban logistics, vehicle routing, and greenhouse emissions, this book is ideally designed for civil/transport engineers, planners, transport economists, geographers, computer scientists, practitioners, professionals, researchers, and students seeking current research on urban goods modelling.

Abstract

International audience; This paper presents a general framework to assess urban rail logistics suitability via a socio-economic cost benefit analysis and demand catchment assessment. First, we examine the main background issues related to data production in urban logistics and the needs of examining the economic viability of future projects. Second, we present methodology proposed that combines a classical CBA framework with a freight catchment analysis framework. Third, as an example of application, we propose to assess freight tramway deployment scenarios in Paris, France. The results show the potential of including demand catchment analysis in CBA to identify the suitable demand introduction strategy. However, it seems important to contextualize them, such methods being used to support decisions and not to substitute decision maker.

Abstract

FloodRisk, 3rd European Conference on Flood Risk Management, Lyon, FRA, 17-/10/2016 - 21/10/2016; International audience; Indicator of Intense Pluvial Runoff (French Acronym) - is a method to map the susceptibility of territories to surface runoff generation, transfer and accumulation. The method is based on a geomatic combination of landscape factors extracted from topography, land use and soil type. This study is part of the method evaluation process and suggests using information from post-event surveys of surface runoff events to evaluate the agreement between the IRIP maps and the field observations. Surface runoff susceptibility maps are produced at five meters resolution for three impact areas on railways with different infrastructure and environment configurations. First, information categories are extracted from the post-event surveys, and then the IRIP maps are analyzed to see if and how the information categories are retrieved. This study shows that the IRIP maps fit the impact description. The areas susceptible to surface runoff transfer fit the gullies locations and the areas susceptible to surface runoff accumulation fit the sediment deposit traces. The comparison also highlights that the IRIP maps can give further information on the event spatial dynamics. Given the simplicity and the robustness of the mapping method, IRIP can be a tool to perform surface runoff post-event surveys and to improve the surface runoff hazard assessment.

Abstract

Nowadays, the operation of a drinking water supply network can be assessed by using hydraulic computer models, such as "Porteau", developed by Cemagref. These models are accurate for high volume flows (such as emptying or filling of tanks) but less so for minimum flows. Partially closed valves, small diameter pipes and overestimation of consumption lead to difficult numerical problems. In these cases, optimization is required to prevent non-convergence of solutions. Besides, for such a model, consumption is an input and has to be estimated without considering the available pressure. Thus, demand overestimation is emphasized at the time of a network dysfunction, such as pipe breaks, pump failures and missing water resources. For about ten years, authors have proposed demand depending on available head. Such a model is known as a "Pressure Driven Model" (PDM), but theory and solving tools have not been fully developed yet.Firstly, two problems of optimization are associated to (PDM): one is written in terms of head loss and head, and the other in terms of flow rates. As with the classical models, they correspond to principles of least action. Next, equivalence of formulations and solution existence and uniqueness are demonstrated. Then, three descent algorithms of Newton type are proposed. Finally, the efficiency of these algorithms is proved in solving former problematic study cases.; De nos jours, le fonctionnement d'un réseau d'alimentation en eau potable peut être apprécié en utilisant un logiciel de calcul hydraulique, tel que " Porteau " développé par le Cemagref. Les résultats sont précis pour la prédiction des échanges de débits importants (tels que le remplissage ou la vidange d'un réservoir) ; ils le sont moins pour les petits débits. Des vannes partiellement fermées, des conduites de petits diamètres et la sur-estimation de la consommation conduisent à des problème numériques raides. Résoudre un problème d'optimisation par une méthode de descente empêche les situations de non-convergence. D'un autre côté, la consommation est fixée au préalable et doit être estimée sans tenir compte de la pression disponible. Ainsi, le problème de la sur-estimation de la demande est accentué lors d'un dysfonctionnement du réseau, tel qu'une casse de conduite, un non-fonctionnement de pompe ou un déficit de la ressource en eau. Depuis à peu près dix ans, les auteurs ont proposé des modèles avec consommation dépendant de la pression (PDM). Cependant, la théorie et les moyens de résolution n'ont pas été complètement développés jusqu'ici.Tout d'abord, deux problèmes d'optimisation sont associés aux PDM modèles : l'un est formulé dans l'espace des charges et des pertes de charges, et l'autre dans l'espace des débits. Comme pour les modèles classiques (avec demande ne dépendant pas la pression), ils correspondent à des principes de moindres actions. Ensuite, l'équivalence des formulations ainsi que l'existence te l'unicité sont démontrés. Alors, trois algorithmes de descente de type Newton sont proposés. Finalement, l'efficacité de ces algorithmes est prouvée en résolvant pour des cas d'école posant au préalable problème.

Abstract

Epidemiological studies suggest that the main part of chronic effects from air pollution is likely to be linked with particulate matter (PM). Oxidative potential (OP) of PM is gaining strong interest as a promising health exposure metric. This study combined atmospheric detailed composition results obtained for seven different urban background environments over France to examine any possible common feature in OP seasonal variations obtained using two assays (acid ascorbic (AA) and dithiothreitol (DTT)) along a large set of samples ( N > 700 ). A remarkable homogeneity in annual cycles was observed with a higher OP activity in wintertime at all investigated sites. Univariate correlations were used to link the concentrations of some major chemical components of PM and their OP. Four PM components were identified as OP predictors: OC, EC, monosaccharides and Cu. These species are notably emitted by road transport and biomass burning, targeting main sources probably responsible for the measured OP activity. The results obtained confirm that the relationship between OP and atmospheric pollutants is assay- and location-dependent and, thus, the strong need for a standardized test, or set of tests, for further regulation purposes. Document type: Article