Abstract:The Environmental Noise Directive (END) requires that regular updating of noise maps is implemented every five years to check and report about the changes occurred during the reference period. The updating process is usually achieved using a standardized approach, consisting in collating and processing information through acoustic models to produce the updated maps. This procedure is time consuming and costly, and has a significant impact on the budget of the authorities responsible for providing the maps. Furthermore, END requires that simplified and easy-to-read noise maps are made available to inform the public about noise levels and actions to be undertaken by local and central authorities to reduce noise impacts. To make the updating of noise maps easier and more cost effective, there is a need for integrated systems that incorporate real-time measurement and processing to assess the acoustic impact of noise sources. To that end, a dedicated project, named DYNAMAP (DYNamic Acoustic MAPping), has been proposed and co-financed in the framework of the LIFE 2013 program, with the aim to develop a dynamic noise mapping system able to detect and represent in real time the acoustic impact of road infrastructures. In this paper, after a comprehensive description of the project idea, objectives and expected results, the most important steps to achieve the ultimate goal are described.
Featured Application: The method discussed in this paper has applications in the context of predicting traffic noise in large urban environments. The system designed by the authors provides an accurate description of traffic noise by relying on measurements of road noise from few monitoring stations appropriately distributed over the zone of interest. A prescription is given of how to choose the location of the noise stations.Abstract: Dynamap, a co-financed project by the European Commission through the Life+ 2013 program, aims at developing a dynamic approach for noise mapping that is capable of updating environmental noise levels through a direct link with a limited number of noise monitoring terminals. Dynamap is based on the idea of finding a suitable set of roads that display similar traffic noise behavior (temporal noise profile over an entire day) so that one can group them together into a single noise map. Each map thus represents a group of road stretches whose traffic noise will be updated periodically, typically every five minutes during daily hours and every hour during night. The information regarding traffic noise will be taken continuously from a small number of monitoring stations (typically 24) appropriately distributed over the urban zone of interest. To achieve this goal, we have performed a detailed analysis of traffic noise data, recorded every second from 93 monitoring stations randomly distributed over the entire urban area of the City of Milan. Our results are presented for a restricted area, the urban Zone 9 of Milan. We have separated the entire set of (about 2000) stretches into six groups, each one represented by a noise map, and gave a prescription for the locations of the future 24 monitoring stations. From our analysis, it is estimated that the mean overall error for each group of stretches (noise map), averaged over the 24 h, is about 2 dB.
We present experimental and numerical results on intense-laser-pulse-produced fast electron beams transport through aluminum samples, either solid or compressed and heated by laser-induced planar shock propagation. Thanks to absolute K yield measurements and its very good agreement with results from numerical simulations, we quantify the collisional and resistive fast electron stopping powers: for electron current densities of % 8 Â 10 10 A=cm 2 they reach 1:5 keV= m and 0:8 keV= m, respectively. For higher current densities up to 10 12 A=cm 2 , numerical simulations show resistive and collisional energy losses at comparable levels. Analytical estimations predict the resistive stopping power will be kept on the level of 1 keV= m for electron current densities of 10 14 A=cm 2 , representative of the full-scale conditions in the fast ignition of inertially confined fusion targets. In the fast ignition (FI) scheme of inertial confinement fusion, a relativistic electron beam (REB) heats the compressed core and ignites the fusion reactions in a capsule of deuterium and tritium [1]. This REB is generated at the critical density surface, or at the cone tip of a cone-embedded imploded capsule [2] by a high-intensity (% 10 20 W=cm 2 ) and high-energy ($100 kJ) laser. The REB source has a total kinetic energy & 40% of the laser energy [3][4][5] and a mean kinetic energy of 1-2 MeV (to provide an efficient coupling to the dense core). The REB transports energy from the generation region (with density and temperature in the level of a few g=cm 3 and a few eV, respectively) to the high-density ($ 400 g=cm 3 ) and hightemperature ($ 300 eV) core, where it must deliver a minimum of 20 kJ to heat the fuel to thermonuclear temperatures ($ 5-10 keV) [6]. The energy transport efficiency can be limited by such physical processes as collisional or collective energy loss [7], divergence [8,9], filamentation [10][11][12], etc. The energy losses over the highly inhomogeneous electron transport zone should be accurately predicted for a successful full-scale FI design. In particular, the REB stopping power should be limited to a few keV= m over the $100 m standing-off distance between the REB source and the imploded core.The work presented here aims at characterizing the REB stopping power in dense media in underscaled experimental conditions. The measurements are used to benchmark a REB transport code. The tested transport media, ranging from solid to warm dense matter, are much denser than the injected REB, being reasonable to assume an efficient neutralization of the injected current (j h ) by a counterstreaming current (j e ) of background thermal electrons (j h % Àj e ). Under these conditions, the numerical description of the REB transport often uses the so-called hybrid approach, where the incident and weakly collisional electrons are modeled kinetically and the highly collisional return current is described as an inertialess fluid [10,13,14].Most of the REB transport experiments carried out up to now have used solid targets [8,15...
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