Showing papers by "University of Lorraine published in 2000"

Simulation of the Behaviour of a powered Wheelchair using Virtual Reality

Abstract: This paper describes the firsts results of a project of simulator for powered wheelchair, using Virtual Reality. We have simulated the kinematics of an existing intelligent wheelchair, which was designed in order to facilitate the driving of a powered wheelchair. We also present the integration of modeled ultrasonic sensors in the simulation.

GéDériF: Automatic Generation and Analysis of Morphologically Constructed Lexical Resources

Abstract: One of the major frequent problems in text retrieval comes from large number of words encountered which are not listed in general language dictionaries. However, it is very often the case that these words are morphologically complex, and as such have a meaning which is predictable on the basis of their structure. Furthermore, such words typically belong to specialized language uses (e.g. scientific, philosophical or media technolects). Consequently, tools for listing and analysing such words can help enrich a terminological database. The purpose of this paper is to present a system that automatically generates morphologically complex lexical French items which are not listed in dictionaries, and that furthermore provides a structural and semantic analysis of these items. The output of this system is a morphological database (currently in progress) which forms a powerful lexical resource. It will be very useful in Natural Language Processing (NLP) and in IR (Information Retrieval) applications. Indeed the system generates a potentially infinite set of complex (derived) lexical units (henceforth CLUs) automatically associated with a rich array of morpho-semantic features, and is thus capable of dealing morphologically complex structures which are unlisted in dictionaries.

Trimethylsulfonium and trimethylsulfoxonium as versatile epoxidation reagents. A comparative study

Abstract: The formation of 1-aryl-2,3,4,5-tetrahydro-1H-3-benzazepine can be carried out by condensation between a phenethylamine and aryl and/or hetaryl-oxiranes, followed by cyclisation of the formed alcohol. Several classical methods allow the preparation of aryl oxiranes but when applied to benzo-fused heterocycles, the results are dramatically different clearly showing the lack of comparative studies on this topic. The versatility of the use of trimethylsulfonium chloride, under basic conditions, for the formation of aryl and/or hetaryl-oxiranes has been clearly demonstrated in this work.

New precise determination of the high temperature unusual temperature dependent thermopower of liquid divalent cadmium and zinc

Abstract: We do not know any precise measurement of the absolute thermopower (ATP) of liquid cadmium and zinc at high temperatures. For liquid cadmium, there are, in the literature, apparent contradictory results. Bath and Kliem and North and Wagner observed that the ATP increases with temperature between 350 °C and 650 °C, but Bradley observed the opposite behaviour between 600 °C and 750 °C. In this work we measured accurately the absolute thermopower of liquid cadmium from the melting point up to 900 °C. We find a maximum around 520 °C, and then the thermopower decreases down to a surprising negative value. To our knowledge, it is the first time that such an unusual behaviour is reported. Nevertheless, it is qualitatively consistent with all the authors mentioned and the apparent contradictory results should only be due to the different temperature ranges of measurements. Using the ATP expression from the Faber-Ziman formalism, we can fit very well the experimental absolute thermopower versus temperature curve with only one adjustable parameter. For this, we have considered that the temperature dependence of the ATP is dominated by the resistivity, and we have introduced the experimental resistivity temperature dependence in the ATP expression. The very good fitting quality demonstrates that our hypothesis is consistent. In contrast, the liquid zinc ATP only increases with temperature. Nevertheless, near 1100 °C, the highest temperature achieved, it shows saturation that may be an indication of a decrease at higher temperature. The same type of fitting gives also quite good results.

Pour une synthese quantitative de la litterature: une meta-analyse menee sur la relation syndicat-productivite

Abstract: L'etape preliminaire a toute recherche consiste a examiner la litterature portant sur son objet d'etude Une des formes que ce processus peut prendre consiste a generaliser les resultats d'etudes singulieres, c'est-a-dire realiser une revue integrative de la litterature Cette demarche de generalisation empirique consiste a realiser la synthese d'un ensemble d'etudes et peut emprunter deux approches La premiere approche consiste a effectuer un etat de l'art narratif, la seconde constitue une alternative rigoureuse en realisant une synthese quantitative, perspective connue sous le nom de meta-analyse (MULLER, 1988) L'objectif de ce travail est de presenter le processus de la meta-analyse a partir d'une investigation menee sur la relation syndicat-productivite