Dealloying of Cobalt from CuCo Nanoparticles under Syngas Exposure

International audienceThe structure and composition of core−shell CuCo nanoparticles were found to change as a result of cleaning pretreatments and when exposed to syngas (CO + H 2) at atmospheric pressure. In situ X-ray absorption and photoelectron spectroscopies revealed the oxidation state of the particles as well as the presence of adsorbates under syngas. Transmission electron microscopy was used for ex situ analysis of the shape, elemental composition, and structure after reaction. The original core−shell structure was found to change to a hollow CuCo alloy after pretreatment by oxidation in pure O 2 and reduction in pure H 2. After 30 min of exposure to syngas, a significant fraction (5%) of the particles was strongly depleted in cobalt giving copper-rich nanoparticles. This fraction increased with duration of syngas exposure, a phenomenon that did not occur under pure CO or pure H 2. This study suggests that Co and Cu can each individually contribute to syngas conversion with CuCo catalysts

SaintEtiQ: a fuzzy set-based approach to database summarization

In this paper, a new approach to database summarization is introduced through our model named SAINTETIQ. Base

Matériaux pour la dépollution des gaz d'échappement automobile

Les premières législations antipollution ont été mises en place suite à la détection, aux Etats Unis plus particulièrement en Californie, du smog photochimique et des pluies acides, néfastes pour la faune et la flore. Les estimations de la contribution de l'automobile aux émissions de composés, considérés comme précurseurs de ces phénomènes, ont été suffisantes pour provoquer la mise en place de normes draconiennes en matière d'émissions automobiles. Les matériaux catalytiques ont été évalués en tant que solution possible pour réduire les émissions à l'échappement. En Europe, l'utilisation des catalyseurs trois voies a été généralisée sur les véhicules essence fonctionnant à richesse stoechiométrique à partir de 1993. Une nouvelle génération de catalyseurs appelée piège à oxydes d'azote (NOx) est maintenant nécessaire pour le post-traitement des gaz d'échappement des motorisations à essence fonctionnant en mélange pauvre (combustion en présence d'un excès d'oxygène) pour diminuer la consommation et par conséquent réduire les émissions du CO$_2$ connu pour son impact sur l'effet de serre. La dépollution des moteurs diesel via un catalyseur d'oxydation a été généralisée en Europe depuis 1996. La sévérisation des normes européennes impose pour les moteurs diesel le recours à des matériaux spécifiques pour le traitement des oxydes d'azotes et des particules par l'intermédiaire de filtres à particules dont l'efficacité de filtration est supérieure à 95%, mais doivent subir des régénérations périodiques

Image Database Summarization with the SaintEtiQ System

In this paper, a new approach for the summarization of image database is described. A linguistic description of images is first generated from its low level features such as color

Mining a Commercial Banking Data Set: The SaintEtiQ Approach

In this paper, an original approach to database summarization is applied to a massive data set provided by a bank marketing department. The overall summarization process is concerned with the knowledge discovery paradigm, even if purposes of the approach are quite different from those of KDD. The summarization process is intended to find general representations of data overall the database, whereas KDD processes deal with knowledge nugget extraction from data, without prioritizing the cover property

Prototyping and Browsing Image Databases Using Linguistic Summaries

In this paper, a new approach for the summarization of image databases is described. A linguistic description of image is first generated from its low level features such as color. An original incremental summary process, called SAINTETIQ is then applied to the images, leading to a comprehensive set of summaries of parts of the database, hierarchically organized. The summary process is driven by data and relies on background knowledge represented by a fuzzy relational thesaurus. It provides both a proximity measure between terms of color domain, and a way to produce generalized descriptions of summaries. Finally, this article points out usages of the produced summaries. A new method to browse image databases is then presented as well as a way to produce relevant prototypes from groups of images. Those tasks benefit from the linguistic descriptions of summaries provided by SAINTETIQ

Querying the SaintEtiQ Summaries – Dealing with Null Answers

Abstract — The data summarization techniques are usually not provided with tools for end-users to efficiently use the produced summaries. In a previous work, a querying tool for the SAINTETIQ summarization model has been outlined. It takes advantage of the hierarchical structure of those summaries to efficiently describe tuples that satisfy some selection criteria. This querying mechanism can be seen both as a boolean one over the summaries, and as a flexible one over the underlying relational tuples. This paper mainly investigates the case of null answers. It is shown how, in this case, alternative queries with non-null answers can be proposed to the user. I

A Fuzzy Linguistic Summarization Technique for TV Recommender Systems

is resulting in a soaring number of broadcast programs available to viewers. To alleviate this problem, Personal Video Recorders (multimedia platforms which record TV programs on a hard disk) should integrate a recommender system, which purpose is to filter programs according to their relevance. These systems are based on a user profile, acting as a representative for the user's interests. An important research issue resides in going beyond explicitly userdefined profiles