Studio e valutazione delle prestazioni di un velivolo turboelica di nuova concezione

Analisi dell'efficienza energetica dell'Airbus A400M e confronto con il Boeing 737-800. Sviluppo di un modello integrato motore-aereo turboelica. Studio del parametro ETRW. Analisi di sensibilità del degrado del motore e studio delle emissioni

Modélisation mathématique d'expansion de plasma et de décharges électriques

TOULOUSE-INSA (315552106) / SudocSudocFranceF

Clustering route choices methodology for network performance analysis

The Network Macroscopic Fundamental Diagram (NMFD) provides a quick overlook of a network performance. Recent studies show that inhomogeneous density spatial distributions significantly reduce the network efficiency. However, few studies investigate the triggers of such distributions. In this paper, we investigate how route choices influence the level of performance of a network and we propose a complete methodology to analyse such a relationship. To simplify the exploration, route choice alternatives are clustered in homogeneous groups with respect to the percentage of overlapping and a large set of flow distribution among routes is tested. The investigations are conducted using both analytical formulations and simulation techniques based on a mesoscopic traffic flow simulator. Analytical formulations define the boundary between fluid and congested network loading. The sensitivity to route choices is then assessed. Then, route choice effects on the network level of performance is quantified using the NMFD. The different evaluated scenarios confirm that the network performance is highly affected by route choice, both by paths' selection and flow distribution. Moreover, the study of hysteresis loops emerging in the NMFD shows that route choice impacts significantly the spatial distribution of congestion

A volume of fluid method for a two-dimensional plasma expansion problem

International audienc

Does traffic-related calibration of car-following models provide accurate estimations of vehicle emissions?

Fuel consumption or pollutant emissions can be assessed by coupling a microscopic traffic flow model with an instantaneous emission model. Traffic models are usually calibrated using goodness of fit indicators related to the traffic behavior. Thus, this paper investigates how such a calibration influences the accuracy of fuel consumption and NOx and PM estimations. Two traffic models are investigated: Newell and Gipps. It appears that the Gipps model provides the closest simulated trajectories when compared to real ones. Interestingly, a reverse ranking is observed for fuel consumption, NOx and PM emissions. For both models, the emissions of single vehicles are very sensitive to the calibration. This is confirmed by a global sensitivity analysis of the Gipps model that shows that non-optimal parameters significantly increase the variance of the outputs. Fortunately, this is no longer the case when emissions are calculated for a group of many vehicles. Indeed, the mean errors for platoons are close to 10% for the Gipps model and always lower than 4% for the Newell model. Another interesting property is that optimal parameters for each vehicle can be replaced by the mean values with no discrepancy for the Newell model and low discrepancies for the Gipps model when calculating the different emission outputs. Finally, this study presents preliminary results that show that multi-objective calibration methods are certainly the best direction for future works on the Gipps model. Indeed, the accuracy of vehicle emissions can be highly improved with negligible counterparts on the traffic model accuracy.JRC.F.8-Sustainable Transpor

Macroscopic Traffic Dynamics with Heterogeneous Route Patterns

This paper investigates at an aggregated (macroscopic) scale the effects of route patterns on a road network. Four main variables are considered: the production, the mean speed, the outflow and the mean travel distance. First, a simple network with heterogeneous travel distances between origins and destinationsis studied by simulation. It appears that the mean travel distance is not only very sensitive to the changes in the origin-destination (OD) matrix but also to the internal traffic conditions within the network. When this distance is assumed constant as usual in the literature, significant errorsmayappearwhen estimating the outflow at the network perimeter. The OD matrix also modifies the shape of the macroscopic fundamental diagram (MFD) to a lesser extend. Second, a new modelling framework is proposed to account for multiple macroscopic routes within reservoirs (spatial aggregates of road network) in the context of MFD simulation. In contrast to existing works, partial accumulations are defined per route and traffic waves are tracked at this level. This leads to a better representation of wave propagation between the reservoir frontiers. A Godunov scheme is combined to a HLL Riemannapproximate solver in order to derive the model numerical solutions. The accuracy of theresulting scheme is assessed for several simple cases. The new framework is similar to some multiclass models that have been elaborated in the context of link traffic dynamics.Transport and Plannin