Système d'interprétation de documents techniques

Dans cet article, nous présentons une méthodologie pour l'acquisition et l'interprétation automatique des planches cadastrales françaises. Notre approche a pour but de construire un système basé sur la vision active ainsi que sur une description hiérarchisée du document. Ce système s'appuie sur deux stratégies très librement inspirées de la vision humaine, vision globale et vision locale, en utilisant un «cycle perceptif». A partir de cette proposition, une description du système sera abordée et quelques résultats expérimentaux de traitement seront illustrés

A Kinetic model for alumina sulfation

International audienceSO2 adsorption on alumina and sulfation with SO2 + O2 have been investigated by IR spectroscopy and thermogravimetric measurements at temperatures quite similar to Claus process plant operating conditions (280-350°C). The sulfation was studied under various P(SO2) and P(O2) pressures. The results allow a kinetic model for alumina sulfation to be proposed. The elementary steps of the mechanism involve two types of surface site. The same site contributes to SO2 adsorption as sulfite and to sulfate formation. Another catalytic site leads to oxygen dissociation. On pure alumina the number of this last site is very low. The model enables the weight gain due to the fixation of SO2 and O2 to be expressed as a function of time. Kinetic constants were calculated from various sulfation experiments and the theoretical expression so obtained fits the experimental curves

An Integrated Photoelectrochemical-Chemical Loop for Solar-Driven Overall Splitting of Hydrogen Sulfide

Abundant and toxic hydrogen sulfide (H2S) from industry and nature has been traditionally considered a liability. However, it represents a potential resource if valuable H2 and elemental sulfur can be simultaneously extracted through a H2S splitting reaction. Herein a photochemical-chemical loop linked by redox couples such as Fe 2+/Fe3+ and I-/I3 - for photoelectrochemical H2 production and H2S chemical absorption redox reactions are reported. Using functionalized Si as photoelectrodes, H2S was successfully split into elemental sulfur and H2 with high stability and selectivity under simulated solar light. This new conceptual design will not only provide a possible route for using solar energy to convert H2S into valuable resources, but also sheds light on some challenging photochemical reactions such as CH4 activation and CO2 reduction. Trash to Treasure: A photochemical-chemical loop for the overall H2S splitting was developed by integrating photoelectrochemical H2 production and H2S chemical absorption redox reactions with the link of a redox couple (Fe2+/Fe3+ or I-/I3 -). Using functionalized silicon as photoelectrode, simultaneous extraction of H2 and elemental sulfur from H2S was successfully achieved (see picture)