Showing papers by "University of Avignon published in 1990"
TL;DR: The familiar Fenchel-Moreau-Rockafellar duality scheme deduced from a conjugation is shown to be applicable to quasi-convex problems and quasi-affine functions take the place of affine functions.
Abstract: The familiar Fenchel-Moreau-Rockafellar duality scheme deduced from a conjugation is shown to be applicable to quasi-convex problems. Here quasi-affine functions take the place of affine functions. The links with other quasi-convex dualities are examined.
132 citations
TL;DR: In this paper, the influence of rotating aluminium alloy flows, driven by a stationary electromagnetic field, during freezing in a toroidal mold, was studied. But the experiments were performed in the absence, and in the presence, of forced cooling.
44 citations
TL;DR: In this article, the reaction du melange thioacetate de potassium-acide thIOacetique avec l'azido-2 benzylidene-4,6 desoxy-2 O-methyl-1 O-trifluoromesyl-3 gulopyranoside was studied.
27 citations
TL;DR: In this article, a condition for the stability of a quasi-convex program under perturbation of the objective functions and the constraint sets was given, and the condition was extended to the case of convex-valued multifunctions.
Abstract: Combining a result on the lower semicontinuity of the intersection of two convex-valued multifunctions and the level set approach of epi-convergence, we obtain results on the epi-upper semicontinuity of the supremum and the sum of two families of quasi-convex functions. As a consequence, we give some condition ensuring the stability of a quasi-convex program under a perturbation of the objective functions and the constraint sets.
20 citations
TL;DR: The study has shown the improvement of madder roots extraction both quantitatively and qualitatively using the efficiency of ultrasound-assisted extraction in comparison with magnetic agitation and reflux techniques.
Abstract: Introduction – Madder (Rubia tinctorum) has been used since ancient times as a source of pigments for dyeing and painting. Madder dyes are localised in roots and the native chemical population is composed of glycosiled and aglycone compounds. The aim of this study is to elaborate an efficient extraction process without any chemical denaturation of dyes.
Objective – To compare an optimised ultrasonic process, using for madder dye extraction, with two conventional procedures and to determine the efficiency of ultrasound on these vegetable matrix.
Methodology – Madder roots were extract in a methanol–water mixture in 37 : 63 (v/v) for ultrasound and 80 : 20 (v/v) for reflux and agitation. HPLC-PAD analyses showed the anthraquinone proportion for each extraction process and their denaturing effects. Finally, cytohistological observations were made to show the consequence of each process on the cell organisation in madder roots.
Results – The results showed that the amount of extracted dyes was higher with UAE than with agitation and reflux. HPLC-PAD analysis revealed that the anthraquinone composition differed according to the extraction procedure. The UAE extracts presented an important richness in terms of anthraquinonic compounds that suggests a preserving effect. Cytohistological observations showed that the main alterations concerned the cell walls of phloem. After UAE the walls exhibited numerous pitted areas reflecting an ultrasound-induced cavitation that enhances the extraction effectiveness of this method.
Conclusion – The study has shown the improvement of madder roots extraction both quantitatively and qualitatively using the efficiency of ultrasound-assisted extraction in comparison with magnetic agitation and reflux techniques. Copyright © 2009 John Wiley & Sons, Ltd.
5 citations
TL;DR: In this article, a site experimental dans un bas-fond rizicole in Madagascar was used to investigate the relation hydrauliques entre surface and souterrain.
2 citations
01 Jan 1990
TL;DR: Two automatic theorem proving algorithms in Propositional Calculus are presented which enabled us to develop the Boolean Constraint processing module in Prolog III.
Abstract: The new concept of constraint logic programming gives rise to languages whose specifications create a requirement for theorem provers in different domains. Here we present two automatic theorem proving algorithms in Propositional Calculus which enabled us to develop the Boolean Constraint processing module in Prolog III.