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Tunis, Tunisia

Gherairi S.,Laboratory ENSI | Ouni S.,INSAT | Kamoun F.,Computer Science Laboratory ENSI
2011 International Conference on Communications, Computing and Control Applications, CCCA 2011 | Year: 2011

In order to eliminate the interferences between neighbors and reduce the delay, with the respect of the real time constraint, we focus our work on the multi-frequency scheduling access protocols. In this paper, we review the most multifrequency MAC protocols which deploy more than one frequency to transmit data to neighbors. After that, we propose an optimized TDMA multi-frequency scheduling access contribution for sensor networks which is based on three phases. In the first phase, we assign frequencies based on parent node reception in communication tree structure. The reduction of the number of frequencies is provided, in phase two, based on the principle of the graph coloring. Finally, in the last phase, we reduce frequencies to the maximum number of allowed frequencies with TDMA (Time Division) clustering principle. Our results are compared with the other works and have showed that our strategy can remove more interference between neighbors, optimize communication delay and adapt with the maximum number of frequencies in WSN (Wireless Sensor Networks). © 2011 IEEE.

Mabrouk W.,ERAS Labo | Mabrouk W.,French National Conservatory of Arts and Crafts | Mabrouk W.,Analytical Chemistry and Electrochemical Laboratory | Ogier L.,ERAS Labo | And 4 more authors.
Journal of Membrane Science | Year: 2014

Synthesis and characterization of new ion exchange membranes made from chlorosulfonated polyethersulfone (SO2Cl-PES) crosslinked by polyaminated crosslinking reagents have been performed. Two examples are described: one crosslinked by hexane diamine, the other by amino-polyethersulfone (NH2-PES). Sulfonated polyether sulfone (S-PES) and NH2-PES have similar chemical structures that allow compatibility. Surprisingly enough, better results were obtained using amino-polyethersulfone. The best results have been obtained using SO2Cl-PES with 1.3 SO2Cl group per monomer unit crosslinked by 0.2 equivalent of NH2-PES. The membranes, less brittle than pristine SPES and insoluble in solvents such as DMAc, were characterized by TGA, DMA, DSC, ionic conductivity, transport numbers, and water swelling. The results showed that these membranes presented very promising performances for use in Proton Exchange Membrane Fuel Cells. © 2013 Elsevier B.V.

Ben Khaled R.,ISI Ariana | Mnasri C.,ISSAT Mateur | Gasmi M.,INSAT
International Review of Automatic Control | Year: 2013

This paper presents a new direct adaptive decentralized controller for a class of large-scale nonlinear systems in strict feedback form. Based on backstepping approach, the direct scheme is developed using Fuzzy Logic Systems to approximate the control signals. A main advantage of this method is that for each subsystem, only one parameter is needed to be adjusted. It is shown, through an original procedure that the designed local adaptive controllers can globally stabilize the overall interconnected system asymptotically, and ensure the convergence of system outputs to a small neighbourhood of the reference signals. Simulation results demonstrate the effectiveness of the proposed approach. © 2013 Praise Worthy Prize S.r.l. - All rights reserved.

Chaabouni M.,INSAT ISI | Laroussi M.,INSAT
CEUR Workshop Proceedings | Year: 2012

We present in this paper the definition of a collaborative and cooperative platform, exploited through the Cloud, for analyzing learners tracks and managing indicators in educational scenarios. This paper describes the architecture and the design proposed for the platform, then it evocates the related security aspect. Finally, a test scenario is described to demonstrate the platform functionalities.

Ghorbel D.,Center Urbain Nord | Barbouche N.,Center Urbain Nord | Riahi H.,Center Urbain Nord | Braham A.,INSAT | Attia H.,University of Sfax
Journal of Food Process Engineering | Year: 2011

Flow properties of nine ice cream compound coatings having different total fat contents were studied with the coaxial geometry in the shear rate range 520-1,200/s. The resulting rheograms were best fit by the Casson-Steiner model, with good values of the coefficient of determination (R2). These coatings were used in the melt state to enrobe ice cream bars by means of an electro-pneumatic system used in lab-scale to reproduce industrial conditions (controlled dipping rate and time). Fat content was seen to determine significantly the coating flow properties and its solidification characteristics. The plastic viscosity and the yield stress were well correlated to the coating thickness and the draining time, which would aid to a better control of the coating process in industry. PRACTICAL APPLICATIONS In the food industry, the achievement of the formulation step in product development needs a good understanding of the techno-functional properties of the ingredients employed. Important quantities of vegetable fats play a part in the formulation of ice cream compound coatings, but their role in the determination of the coating qualities is not well clarified. The aim of this work was to evaluate the influence of fat content on the rheological properties of ice cream compound coatings used to enrobe ice cream bars and to examine the relationships with thickness after dip coating. © 2009 Wiley Periodicals, Inc.

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