Search results for "Transportation"
showing 10 items of 860 documents
Finite speed of propagation in porous media by mass transportation methods
2004
Abstract In this Note we make use of mass transportation techniques to give a simple proof of the finite speed of propagation of the solution to the one-dimensional porous medium equation. The result follows by showing that the difference of support of any two solutions corresponding to different compactly supported initial data is a bounded in time function of a suitable Monge–Kantorovich related metric. To cite this article: J.A. Carrillo et al., C. R. Acad. Sci. Paris, Ser. I 338 (2004).
Estimation of Passenger Car Equivalents for single-lane roundabouts using a microsimulation-based procedure
2017
Calibration of microscopic traffic simulation models for single-lane roundabouts.Use of a meta-analytical estimation of critical and follow up headways.Use of a genetic algorithm-based procedure.Calculation of passenger car equivalents for single-lane roundabouts. Passenger car equivalents for heavy vehicles are required to carry out capacity calculations and perform operational analysis of any road entity (roadway segments or intersections). At single-lane roundabouts, the constraints to the vehicular trajectories imposed by the curvilinear geometric design and the driver's gap acceptance behaviour are expected to produce an impact of the heavy vehicles on the quality of traffic flow diffe…
Hamilton–Jacobi semi-groups in infinite dimensional spaces
2006
AbstractLet (X,ρ) be a Polish space endowed with a probability measure μ. Assume that we can do Malliavin Calculus on (X,μ). Let d:X×X→[0,+∞] be a pseudo-distance. Consider QtF(x)=infy∈X{F(y)+d2(x,y)/2t}. We shall prove that QtF satisfies the Hamilton–Jacobi inequality under suitable conditions. This result will be applied to establish transportation cost inequalities on path groups and loop groups in the spirit of Bobkov, Gentil and Ledoux.
Transportation-cost inequality on path spaces with uniform distance
2008
Abstract Let M be a complete Riemannian manifold and μ the distribution of the diffusion process generated by 1 2 ( Δ + Z ) where Z is a C 1 -vector field. When Ric − ∇ Z is bounded below and Z has, for instance, linear growth, the transportation-cost inequality with respect to the uniform distance is established for μ on the path space over M . A simple example is given to show the optimality of the condition.
A GIS-Based Method to Assess the Pedestrian Accessibility to the Railway Stations
2018
Modern cities, affected by congestion, atmospheric and acoustic pollution, land consumption, should change and return to being on a human scale, rather than designed for cars. Proper land-use planning, infrastructure improvement and implementation of targeted interventions have to ensure that there is a rapprochement of citizens about the public transport, in order to reduce these problems. An important aspect of modal choice by users of the public transport system is, however, linked to the quality of the pedestrian routes. In fact, every journey made by public transport begins and finishes on foot. Therefore, studying pedestrian accessibility to transit stations and the walkability of the…
The Challenges of Urban Mobility Regulation and the New Urban Agenda
2019
The objectives set by the United Nations New Urban Agenda pose important challenges to the traditional regulation of urban mobility in our cities. Regardless of the region of the world in question and its level of development, the goals established by the Agenda expose the importance of improving urban mobility regulation. Therefore, some traditional regulatory approaches need to be modified or intensified, which is potentially difficult in certain cases. In addition, and complicating the matter further – as well as being more interesting from an academic perspective – the disruptive emergence of new agents and market niches related to urban transportation (such as digital sharing platforms…
An empirically grounded agent based simulator for the air traffic management in the SESAR scenario
2017
In this paper we present a simulator allowing to perform policy experiments relative to the air traffic management. Different SESAR solutions can be implemented in the model to see the reaction of the different stakeholders as well as other relevant metrics (delay, safety, etc). The model describes both the strategic phase associated to the planning of the flight trajectories and the tactical modifications occurring in the en-route phase. An implementation of the model is available as an open-source software and is freely accessible by any user. More specifically, different procedures related to business trajectories and free-routing are tested and we illustrate the capabilities of the mode…
Identification of Bending Modes of Vibration in Rails by a Laser Doppler Vibrometer on a Moving Platform
2020
This paper introduces a method to identify the bending modes of vibration of railway tracks by using a laser Doppler vibrometer (LDV) mounted on a moving platform. Two sets of experiments were conducted at Transportation Technology Center Inc. (TTCI) in Pueblo Colorado, in order to validate the proposed method. First, the bending vibration modes were identified using the signals collected from a rail span (rail section between two consecutive sleepers) by accelerometers under moving car excitation. Then, vibration measurements from rail spans were obtained by using an LDV mounted on the moving railcar. All tests were carried out at four different rail car speeds: 8 km/h (5 mph), 16 km/h (10…
An overestimated relationship? Violent political unrest and tourism foreign direct investment in the Middle East
2010
Although the tourism industry is increasingly globalising, empirical research on the accompanying foreign direct investment (FDI) is surprisingly lacking. Furthermore, the nexus of political risk, violent political unrest and tourism FDI has been relatively neglected. Using Egypt as a heuristic case study and adopting a qualitative methodology, this paper explores the question of how political risk and violent political unrest influence tourism FDI. Surprisingly, the results are not able to corroborate a clear relationship between the two. In contrast, these results indicate that the role of stability and security for tourism FDI in developing countries has largely been overestimated in the…
Estimating pollutant emissions based on speed profiles at urban roundabouts: A pilot study
2019
The paper describes the pilot study conducted to assess the feasibility of the empirical approach utilizing vehicle trajectory data from a smartphone app and the Vehicle-Specific Power methodology to estimate pollutant emissions at urban roundabouts. The goal of this research phase is to acquire instantaneous speed data from a sample of six roundabouts located in the road network of the City of Palermo, Italy, and quantify emissions generated by the test vehicle through the examined roundabouts. For the case studies of roundabouts acceleration events in the circulating and exiting areas contributed to about 25% of the emissions for a given speed profile. More in general, the results from th…