A nonlinear random walk approach to concentration-dependent contaminant transport in porous media

We propose a nonlinear random walk model to describe the dynamics of dense contaminant plumes in porous media. A coupling between concentration and velocity fields is found, so that transport displays non-Fickian features. The qualitative behavior of the pollutant spatial profiles and moments is explored with the help of Monte Carlo simulation, within a Continuous Time Random Walk approach. Model outcomes are then compared with experimental measurements of variable-density contaminant transport in homogeneous and saturated vertical columns.Comment: 8 pages, 9 figure

Les réseaux de neurones récurrents : un outil pour la modélisation des bioprocédés. Application à la production de levains : 1ère partie

National audienc

Les réseaux de neurones récurrents : un outil pour la modélisation des bioprocédés. Application à la production de levains : 2ème partie : application à des procédés de fermentation

National audienc

A tool to guide the selection of impact categories for LCA studies by using the representativeness index

Industrial Ecolog

A switching control strategy based on alkalinity to optimize biogas outflow in the start-up of an anaerobic digester

International audienceThis paper deals with the control of the start-up phase in anaerobic digestion systems by using monitoring parameters already implemented that have been coupled to the control law. Methane yield, as well as methane flow rate, and the ratio of intermediate over total alkalinity have been used as control parameters. These measurements have been included in a switching control strategy to drive the process toward a steady state in which biogas production is optimized avoiding accumulation of volatile fatty acids. Experimental validation of this control strategy has been performed from the results obtained using a 358 litter fixed bed anaerobic digester treating industrial winery wastewater

Role of corpus callosum in interhemispheric coherent activity during sleep

This paper is focused on the experimental implementation of a robust control scheme for the regulation of volatile fatty acids (VFA) in continuous anaerobic digestion processes. The robust scheme is made of an output feedback control, and an extended Luenberger observer is used to estimate the uncertain terms of the process (i.e., influent concentration and process kinetics). The control scheme is implemented in a pilot plant up-flow fixed-bed reactor that is treating industrial wine distillery wastewater. The performance of the robust scheme is tested over a period of 36 days, under different set-point values and several uncertain scenarios, including model mismatch, badly known parameters, and load disturbances. Experimental results show that the VFA concentration can be effectively regulated over a wide range of operating conditions. In addition, it is shown that the control scheme has a structure that improves its performance in the presence of noisy measurements and control input saturations. " 2008 American Chemical Society.",,,,,,"10.1021/ie800256e",,,"http://hdl.handle.net/20.500.12104/44299","http://www.scopus.com/inward/record.url?eid=2-s2.0-54949101656&partnerID=40&md5=f1d20cb3444cd9ceecff9c38fbe82ff

Changes in hydrogenase genetic diversity and proteomic patterns in mixed culture dark fermentation of mono-, di- and tri-saccharides

International audienc