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Gafsa, Tunisia

We present some new variants of Leray-Schauder type fixed point theorems and eigenvalue results for decomposable single-valued nonlinear weakly compact operators in Dunford-Pettis spaces. Copyright © Taylor & Francis Group, LLC. Source


Moussa S.,University of Tunis | Moussa S.,Gafsa University | Touzani M.,University of Tunis
Journal of Informetrics | Year: 2010

This paper provides a ranking of 69 marketing journals using a new Hirsch-type index, the hg-index which is the geometric mean of hg. The applicability of this index is tested on data retrieved from Google Scholar on marketing journal articles published between 2003 and 2007. The authors investigate the relationship between the hg-ranking, ranking implied by Thomson Reuters' Journal Impact Factor for 2008, and rankings in previous citation-based studies of marketing journals. They also test two models of consumption of marketing journals that take into account measures of citing (based on the hg-index), prestige, and reading preference. © 2009 Elsevier Ltd. All rights reserved. Source


Raddaoui M.,Gafsa University
Journal of Turbulence | Year: 2014

Von Karman flows generated by the movement of two contra-rotating discs enveloping a fixed cylinder are an important source of turbulence, especially if they are associated with some tools such as rotating baffles. This work is to model the effect of the baffles height on the mean and turbulent quantities of a turbulent Von Karman flow using an experimental study and a numerical simulation through a stationary two-dimensional Reynolds-Averaged Navier Stokes (RANS-2D) axisymmetric model. The experimental results are obtained by laser Doppler anemometry. The numerical simulation is based on one-point statistical modelling using a low Reynolds number second-order full stress transport closure (Reynolds Stress Model [RSM]). The effect of baffles height is modelled by a source term, which is added only to the equation of mean tangential velocity. The comparison with experiments provides confidence of this modelling technique. Simulations reveal that the height of baffle is a very important parameter which affects both mean and turbulence quantities. The originality of this work is essentially the development of correlations between certain characteristics of the flow and the baffles height showing then that this parameter is an interesting tool which can guide both the level and the structure of turbulence in Von Karman flows. © 2014 Taylor & Francis. Source


Elghniji K.,University of Sfax | Ksibi M.,University of Sfax | Elaloui E.,Gafsa University
Journal of Industrial and Engineering Chemistry | Year: 2012

A series of N-substituted titanium (IV) 2-ethyl-1,3-hexanediolate Ti(C 32H 68O 8) precursor were synthesized by the sol-gel reverse micelle (SGRM) method. The ethylene diaminetetraacetic acid (Na 2EDTA) has been used as a source of nitrogen n species. The obtained solids were calcined at 500°C for 1h to obtain photoactive phases. The effect of nitrogen content (N/Ti=0.025; 0.03; 0.05 atomic ratios) is examined. The materials were characterized by XRD, BET, TG/DTA and UV-vis reflectance spectroscopy (DRS). Photocatalytic decolourisation of methylen blue (MB) in aqueous solution was carried out using nano, doped TiO 2. Experimental results revealed that N/Ti=0.05 atomic ratio N-doped TiO 2 required shorter irradiation time for complete decolourisation of MB than pure nano TiO 2 and commercial (Degussa P-25) TiO 2. © 2011 The Korean Society of Industrial and Engineering Chemistry. Source


Hassen D.B.,University of Tunis | Taleb H.,Gafsa University
Clinical Imaging | Year: 2013

This article presents a novel approach for the automatic detection of lesions and selection of features on chest radiographs. We have illustrated the importance of accurate segmentation, which is based on spatial relationships between the lung structures, as a preprocessing step in a Computer Aided Diagnosis (CAD) scheme. Then, three suitable combinations of features have been identified using the forward stepwise selection method from the original images and their transformed ones. Experimental results show that our segmentation approach and the suppression of skeletal structures improve the detection accuracy. The selected features can describe efficiently different kinds of chest lesions. © 2013 Elsevier Inc. Source

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