Vers une prédiction automatique de la difficulté d'une question en langue naturelle

International audienceNous proposons et testons deux méthodes de prédiction de la capacité d'un système à répondre à une question factuelle. Une telle prédiction permet de déterminer si l'on doit initier un dialogue afin de préciser ou de reformuler la question posée par l'utilisateur. La première approche que nous proposons est une adaptation d'une méthode de prédiction dans le domaine de la recherche documentaire, basée soit sur des machines à vecteurs supports (SVM) soit sur des arbres de décision, avec des critères tels que le contenu des questions ou des documents, et des mesures de cohésion entre les documents ou passages de documents d'où sont extraits les réponses. L'autre approche vise à utiliser le type de réponse attendue pour décider de la capacité du système à répondre. Les deux approches ont été testées sur les données de la campagne Technolangue EQUER des systèmes de questions-réponses en français. L'approche à base de SVM est celle qui obtient les meilleurs résultats. Elle permet de distinguer au mieux les questions faciles, celles auxquelles notre système apporte une bonne réponse, des questions difficiles, celles restées sans réponses ou auxquelles le système a répondu de manière incorrecte. A l'opposé on montre que pour notre système, le type de réponse attendue (personnes, quantités, lieux...) n'est pas un facteur déterminant pour la difficulté d'une question

Statistical method for the determination of the ignition energy of dust cloud-experimental validation

International audiencePowdery materials such as metallic or polymer powders play a considerable role in many industrial processes. Their use requires the introduction of preventive safeguard to control the plants safety. The mitigation of an explosion hazard, according to the ATEX 137 Directive (1999/92/EU), requires, among other things, the assessment of the dust ignition sensitivity. PRISME laboratory (University of Orléans) has developed an experimental set-up and methodology, using the Langlie test, for the quick determination of the explosion sensitivity of dusts. This method requires only 20 shots and ignition sensitivity is evaluated through the E50 (energy with an ignition probability of 0.5). A Hartmann tube, with a volume of 1.3 l, was designed and built. Many results on the energy ignition thresholds of partially oxidised previous termaluminiumnext term were obtained using this experimental device (Baudry, 2007) and compared to literature. E50 evolution is the same as previous MIE but their respective values are different and previous MIE is lower than E50 however the link between E50 and previous MIE has not been elucidated. In this paper, the Langlie method is explained in detail for the determination of the parameters (mean value E50 and standard deviation σ) of the associated statistic law. The ignition probability versus applied energy is firstly measured for Lycopodium in order to validate the method. A comparison between the normal and the lognormal law was achieved and the best fit was obtained with the lognormal law. In a second part, the Langlie test was performed on different dusts such as previous aluminium, cornstarch, lycopodium, coal, and PA12 in order to determine E50 and σ for each dust. The energies E05 and E10 corresponding respectively to an ignition probability of 0.05 and 0.1 are determined with the lognormal law and compared to previous MIE find in literature. E05 and E10 values of ignition energy were found to be very close and were in good agreement with previous MIE in the literature

Hybridization of the Dual-Grid FDTD with the Physical Optics to Analyze Antennas Mounted on Large and Complex Platforms

International audienceThis paper presents a new simulation strategy based on the hybridization of a fullwave time domain multi-scale method, the Dual-Grid FDTD (DG-FDTD), and the Physical Optics (PO). This new method aims at simulating antennas mounted on large conducting platforms and whose nearby surrounding environment is very complex. Typical application fields of the hybrid DG-FDTD/PO method are the computation of radiation patterns of antennas mounted on carriers such as satellites, ships, aircraft and land vehicules

Analysis of Surrounded Antennas Mounted on Large and Complex Structures Using a Hybrid Method

International audienceA new hybrid method, the DG-FDTD/IPO, has recently been proposed to analyze surrounded antennas mounted on large platforms. In this paper the capabilities of this method to go through such large and complex problems are shown. More precisely, a deep analysis of the far-field radiated for a canonical antenna-on-platform scenario is proposed

Rigorous analysis of a satellite antenna including its surrounding environment with the Dual-Grid FDTD method

International audienceThis paper presents a rigorous analysis of a satellite antenna mounted onto its platform using the Dual-Grid FDTD method. In the first step of the method, the isolated antenna is analyzed. The study of the surrounded antenna is carried out in the second step of the DG-FDTD method. The results obtained in this realistic test case show the significant influence of the environment over the antenna

A new hybrid method for the analysis of surrounded antennas mounted on large platforms

International audienceAn efficient technique to provide fast and accurate analysis of wide-band surrounded antennas mounted on electrically large platforms is presented and validated in this paper. The hybrid method combines Dual-Grid FDTD (DG-FDTD) with Iterative Physical Optics (IPO) to analyze on-platform antenna radiation. In section IV of this paper, DG-FDTD/IPO is applied to the analysis of a wide-band antenna mounted on a vehicle. The ability to address the problem of antenna placement is also demonstrated

Hybridation de la DG-FDTD avec l'optique physique fréquentielle pour l'analyse d'antennes sur porteur

National audienceCet article propose une nouvelle méthode hybride destinée à l'analyse du rayonnement, sur une large bande de fréquences, d'antennes présentant un environnement proche complexe et positionnées sur des structures électriquement grandes. On présente ainsi l'hybridation entre une méthode temporelle multi-échelle rigoureuse, la DG-FDTD (Dual Grid-FDTD), et une méthode asymptotique, l'optique physique fréquentielle. Afin d'illustrer les performances de cette méthode, on traite, dans la dernière partie de cet article, le cas d'une antenne placée sur un véhicule

Investigation on the thermal degradation and kinetic parameters of innovative insulation materials using TGA-MS

Thermogravimetric analyzer coupled to a mass spectrometer (TGA-MS) was used to study the thermochemical behavior of eight samples. Two varieties of straw (wheat and barley) and two others of binder (lime and plaster) have employed to design four composites. These composites can be considered as innovative insulation materials for buildings. The thermal degradation of the different specimens was studied from a temperature of 50 to 1000ºC using increased temperature of 20ºC/min. This thermal degradation is an important element to evaluate the fire behavior and predict the evolution of smoke emitted during an accidental fire for building application. Using MS analyzer, the ion currents evolutions of 16 molecule groups (shared by a m/z ratio) were followed as functions of temperature. TG curves show that the thermal decomposition of composite samples is more complex (3-4 mass loss steps) than the one of the basic materials (1-2 mass loss stages) and seems to be mostly affected by the binder nature. The highest amount of gas in pyrolysis products is associated to m/z=28 ratio and presents more than two thirds of the total quantity. The kinetic parameters were evaluated for the more important mass loss of each sample and their values are in the ranges of 8.29-64.86 kJ/mol, 0.4-3.36 and 1.78 x 10^3 -1.63 x 10^7 min^-1 for respectively the activation energy, the reaction order and the pre-exponential factor.Peer ReviewedPostprint (author's final draft

Highlight on Bottlenecks in Food Allergen Analysis:Detection and Quantification by Mass Spectrometry

Abstract Food laboratories have developed methods for testing allergens in foods. The efficiency of qualitative and quantitative methods is of prime importance in protecting allergic populations. Unfortunately, food laboratories encounter barriers to developing efficient methods. Bottlenecks include the lack of regulatory thresholds, delays in the emergence of reference materials and guidelines, and the need to detect processed allergens. In this study, ultra-HPLC coupled to tandem MS was used to illustrate difficulties encountered in determining method performances. We measured the major influences of both processing and matrix effects on the detection of egg, milk, soy, and peanut allergens in foodstuffs. The main goals of this work were to identify difficulties that food laboratories still encounter in detecting and quantifying allergens and to sensitize researchers to them.</jats:p