Influence d'herbicides sur les champignons mycorhiziens et les mycorhizes des plants forestiers

National audienc

Ethanol removal by dielectric barrier discharge assisted by catalysis.

International audienc

Effect of voltage waveform on dielectric barrier discharge ozone production efficiency

Dielectric barrier discharges (DBDs) are commonly used for gas effluent cleanup and ozone generation. For these applications, the energy efficiency of the discharge is a major concern. This paper reports on investigations carried out on the voltage shape applied to DBD reactor electrodes, aiming to evaluate a possible energy efficiency improvement for ozone production. Two DBD reactor geometries were used: pin-to-pin and cylinder-to-cylinder, both driven either by a bi-directional power supply (voltage rise rate 1 kV/μs) or by a pulsed power supply (voltage rise rate 1 kV/ns). Ozone formed in dry air was measured at the reactor outlet. Special attention was paid to discharge input power evaluation using different methods including instantaneous current-voltage product and transferred charge-applied voltage figures. The charge transferred by the discharges was also correlated to the ozone production. It is shown that, in the case of the DBD reactors under investigation, the applied voltage shape has no influence on the ozone production efficiency. For the considered voltage rise rate, the charge deposit on the dielectric inserted inside the discharge gap is the important factor (as opposed to the voltage shape) governing the efficiency of the discharge – it does this by tailoring the duration of the current peak into the tens of nanosecond range

Forces et paradoxes de la planification française du tourisme

International audienceAvec de vastes surfaces et une grande diversité géographique et culturelle, la France est devenue un acteur du tourisme essentiel en Europe. Le présent chapitre présente les principales caractéristiques du tourisme en France, pour ensuite aborder les différentes politiques touristiques, et ce à différentes échelles territoriales. En particulier, dans ce contexte, est discuté le devenir du tourisme national