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Amar A.B.,Gafsa University | Mnif M.,University of Sfax
Mathematical Methods in the Applied Sciences | Year: 2010

Motivated by the study of a general radiative transfer problem, we state some new variants of Leray-Schauder type fixed point theorems for weakly sequentially continuous operators. Further, we apply our results to establish some new existence and locality principles for a source problem in L1-setting with generally boundary conditions. Copyright © 2009 John Wiley & Sons, Ltd.

Younes R.B.,Gafsa University
Numerical Heat Transfer; Part A: Applications | Year: 2010

This work presents an analytical and numerical investigation of the heat transfer problem of turbulent flow under forced convection in a buried co-axial exchanger. A hybrid model consisting of a finite element method at the boundary (BEM) for the heat transfer problem on the boundary, and a finite volume method (FVM) to solve the turbulent flow inside solves this complicated problem. The development of the BEM method is based on Green's functions theory. The mathematical model employed makes a scientific contribution to a similar practical situation. The results can be of great interest for industrial processes requiring the estimation of the heating time necessary to obtain steady states. Essentially, the axial evolution of the heat transfer coefficient versus Reynolds number and transfer duration is treated here. The temperature field and the heat flux density at the wall are also investigated. Copyright © Taylor & Francis Group, LLC.

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.

Rabaaoui N.,University of Sfax | Allagui M.S.,Gafsa University
Journal of Hazardous Materials | Year: 2012

The degradation of 100mL of solution with salicylic acid (SA) in the pH range 3.0-10.0 has been studied by anodic oxidation in a cell with a boron-doped diamond (BDD) anode and a stainless steel cathode, both of 3cm2 area, by applying a current of 100, 300 and 450mA at 25°C. Completed mineralization is always achieved due to the great concentration of hydroxyl radical (OH) generated at the BDD surface. The mineralization rate increases with increasing applied current, but decreases when drug concentration rises from 200mgL-1. Nevertheless, the pH effect was not significant. During oxidation it was observed that catechol, 2,5-dihydroxylated benzoic acid, 2,3-dihydroxylated benzoic acid and hydroquinone were formed as aromatic intermediates. In addition, ion-exclusion chromatography allowed the detection of fumaric, maleic, oxalic and formic as the ultimate carboxylic acid. © 2012 Elsevier B.V.

Ezzinbi K.,Cadi Ayyad University | Ghnimi S.,Gafsa University
Nonlinear Analysis: Real World Applications | Year: 2010

In this paper, we study a class of neutral partial functional integrodifferential equations with finite delay by using the theory of resolvent operators. We give some sufficient conditions ensuring the existence, uniqueness and regularity of solutions. As an application, we also consider a diffusive neutral partial functional integrodifferential equation. © 2009 Elsevier Ltd. All rights reserved.

The chemical composition of the Pelargonium graveolens essential oil allowed the identification of 15 compounds (93.86% of the total essential oil). The major fractions were citronellol (35%) and geraniol (28.8%). The chemical composition of the Artemisia arborescens essential oil revealed twenty-one compounds representing 93.57% of the total essential oil. The main compounds were chamazulene (31.9%) and camphor (25.8%). The insecticidal effects were tested towards the insect Rhysopertha dominica. Results revealed that these two essential oils were highly effective against R. dominica at the dose of 50 μL on Petri dish of 8.5 cm of diameter. The antifungal activity was evaluated against Rhizoctonia solani and results showed that both of the essential oils were highly active at a dose of 12.5 μL/20 mL of PDA. Moreover, the inhibitory effect of P. graveolens essential oil was evidenced as stronger than that of the A. arborescens oil for all the tested doses. © 2013 Taylor and Francis Group, LLC.

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.

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.

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.

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.

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