Evidence for Diverging Barriers in the Disordered Vortex Solid in the K,Ba BiO3 Superconducting Oxide

International audienceVortex dynamics has been investigated in the cubic K, Ba BiO3 superconductor using ac susceptibility measurements on a large frequency range 0.03 Hz , v , 60 kHz . Power law diverging barriers have been obtained on both sides of the order-disorder transition line. The m exponent remains close to 5 2 (elastic creep value) in some part of the disordered phase and finally decreases at high temperature and/or high field, in good agreement with the recent plastic collective creep theory [J. Kierfeld, H. Nordborg, and V. M. Vinokur, Phys. Rev. Lett., 85, 4948 (2000)]

Méthodologie d'évaluation de projet de transport dans le cadre du développement durable

Face à différents projets de transport, tels des projets d'infrastructure routières ou ferroviaires, quel projet est le plus "durable" ? Nous proposons une méthode relativement simple et transparente d'évaluation de tels projets. Cela consiste d'abord à penser les enjeux de transports dans le cadre du développement durable, sous l'acception forte du concept, qui seule permet de prendre en compte sérieusement les enjeux environnementaux. Cela demande aussi d'articuler le local et le global, le court et le long terme, et donc de préciser les échelles géographiques et temporelles des projets et de leurs impacts. Dans un deuxième temps, nous déclinons ces grands principes en critères d'évaluation qui permettent d'opérationnaliser le concept de développement durable. Nous proposons 3 critères économiques, 4 critères sociaux et 11 critères environnementaux, ainsi qu'une méthode d'agrégation de ces critères intégrant les préférences sociales ou politiques des décideurs ou de leurs mandants. Un point souvent important quant aux projets de transport est la prospective de la mobilité et de trafic, dont nous analysons les principaux paramètres, permettant de proposer des scénarios probables, qui sont les données d'entrée des critères retenus ci-dessus. Nous présentons une application à des projets d'infrastructures dans la région lyonnaise.évaluation ; projet ; transport ; développement durable ; indicateur ; agrégation

Recherche à visée sociétale, un enjeu pour nous tous

National audienceNous examinons les caractéristiques des différents types de recherche - fondamentale, appliquée, recherche-développement, sociétale

Assessing the performance of social spending in Europe

Based on the construction of a new composite index to assess the relative performance of welfare policies, we show that the variability of performances cannot be explained only by the amount of resources devoted to social policies, but also by its composition: countries with higher shares of social public expenditure, specifically aimed at reducing income concentration, obtain better results. This associates the traditional classification of the welfare systems to the performance obtained in the social sector

Exhaust emissions of regulated and unregulated pollutants of passenger cars

Exhaust emissions of VOC speciation, aldehydes and other carbonyl compounds, polyaromatics and regulated pollutants are measured using a vehicle bench on a sample of passenger cars. 30 diesel and gasoline cars are tested, complying with ECE 1504 to Euro 3 emission standards, according to 10 real-world driving cycles based on European driving behaviour, with some of them adapted to vehicle size. The emission results of this large-scale measurement campaign show the influence of vehicle technology and driving behaviour on the emission of 100 individual pollutants. In addition, the results are discussed per VOC group and compared with other studies. The influence of the successive emission standards on the emission factors is very positive in most of cases. However, whereas hot CO2 is almost stable, diesel hot NOx, diesel hot and cold VOC, and the 6 most carcinogenic gasoline PAH have increased with standards. Diesel vehicles are less pollutant for CO, HC, CO2, VOC, but more pollutant for NOx and PAH. The distribution of VOC species per molecular family highlights the fact that monoaromatics make up the biggest share (~88 and 62 % resp. for gasoline and diesel vehicles). The second family is the alkanes which contribute resp. 8 and 9% of the total mass of measured VOC. The majority of volatile PAH is observed in the gaseous phase, but the least volatile and the carcinogenic PAH are adsorbed more in particulate phase

Comparative measurements of the energy consumption of 51 electric, hybrid and internal combustion engine vehicles

Accepted versio

Absence of a True Vortex-Glass Phase above the Bragg Glass Transition Line in Bi-2212

In magnetic measurements on Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi-2212) single crystals, a general peak with a dynamical feature on both $S-H$ and $S-T$ curves was found with S the magnetic relaxation rate. At higher fields, the characteristic exponent $\mu$ becomes negative, together with the positive curvature of $logE$ vs. $logj$ and the scaling based on the 2D vortex glass theory or plastic creep theory, we conclude that the vortex motion above the second peak is plastic when $j\to 0$ and there is no vortex glass phase at finite temperatures in Bi-2212. The peak of S is then explained as the crossover between different meta-stable vortex states.Comment: 10 pages, 5 figures, To appear in Physica