Bellik Y.,Universite Ibn Khaldoun
Molecules (Basel, Switzerland) | Year: 2012
The resort worldwide to edible medicinal plants for medical care has increased significantly during the last few years. Currently, there is a renewed interest in the search for new phytochemicals that could be developed as useful anti-inflammatory and anti-allergic agents to reduce the risk of many diseases. The activation of nuclear transcription factor-kappa B (NF-κB) has now been linked to a variety of inflammatory diseases, while data from numerous studies underline the importance of phytochemicals in inhibiting the pathway that activates this transcription factor. Moreover, the incidence of type I allergic disorders has been increasing worldwide, particularly, the hypersensitivity to food. Thus, a good number of plant products with anti-inflammatory and anti-allergic activity have been documented, but very few of these compounds have reached clinical use and there is scant scientific evidence that could explain their mode of action. Therefore, this paper intends to review the most salient recent reports on the anti-inflammatory and anti-allergic properties of phytochemicals and the molecular mechanisms underlying these properties.
Laribi S.,Universite Ibn Khaldoun |
Bendiabdellah A.,Oran University of Science and Technology - Mohamed Boudiaf
International Review of Electrical Engineering | Year: 2010
In this paper, the performance study of the vector control method applied to a three phase squirrel cage induction motor with stator short circuits faults, rotor broken bars faults as well as with both faults simultaneously is being presented. The fault diagnosis technique used in this work is based on the spectral analysis of electrical quantities such as current and voltage. Simulation as well as experimental results are being carried and presented to illustrate the influence of vector control on a faulty squirrel cage induction motor. © 2010 Praise Worthy Prize S.r.l. - All rights reserved.
Benguediab S.,University Djilali Liabes |
Tounsi A.,University Djilali Liabes |
Zidour M.,University Djilali Liabes |
Zidour M.,Universite Ibn Khaldoun |
Semmah A.,University Djilali Liabes
Composites Part B: Engineering | Year: 2014
In this paper, the mechanical buckling properties of a zigzag double-walled carbon nanotube (DWCNT) with both chirality and small scale effects are studied. Based on the nonlocal continuum theory and the Timoshenko beam model, the governing equations are derived and the critical buckling loads under axial compression are obtained. The DWCNTs are considered as two nanotube shells coupled through the van der Waals interaction between them. The equivalent Young's modulus and shear modulus for zigzag DWCNT are derived using an energy-equivalent model. The results show that the critical buckling load can be overestimated by the local beam model if the small-scale effect is overlooked for long nanotubes. In addition, significant dependence of the critical buckling loads on the chirality of zigzag carbon nanotube is confirmed. These findings are important in mechanical design considerations of devices that use carbon nanotubes.© 2013 Elsevier Ltd. All rights reserved.
Mimouni A.,Universite Ibn Khaldoun |
Rachidi F.,Ecole Polytechnique Federale de Lausanne |
Rubinstein M.,Applied Information Sciences
IEEE Transactions on Electromagnetic Compatibility | Year: 2014
We present an analysis of the nearby electromagnetic fields generated by lightning discharges in the presence of a horizontally stratified, two-layer ground. To the best of our knowledge, this is the first time the effect of ground stratification on underground fields generated by lightning is analyzed. The analysis is performed by solving Maxwell's equations using the finite-difference time-domain technique. The return stroke channel is modeled using the modified transmission line model with exponential decay. The effect of the soil stratification on both above-ground fields and the fields penetrating into the ground is illustrated and discussed for two different cases characterized, respectively, by an upper layer more conductive than the lower level, and vice versa. The analysis was carried out for close distances (10 m-100 m from the channel). It is shown that, for these distances, the ground stratification does not significantly affect the electromagnetic fields above the ground. The above-ground vertical electric field and the azimuthal component of the magnetic field can be calculated assuming the ground as a perfectly conducting plane. The above-ground horizontal electric field is essentially determined by the characteristics of the conductive layer and it can be computed considering a homogeneous ground characterized by the conductive layer conductivity as long as the depth of the upper layer remains below 10 m or so. In general, the fields penetrating into the ground are markedly affected by the soil stratification. The electromagnetic field components inside the stratified soil are generally characterized by faster rise times compared to those of the field components in the case of a homogeneous ground with the upper layer characteristics. The peak value of the horizontal electric field is found to be very sensitive to the ground stratification. The horizontal electric field peak decreases considerably in the presence of a lower layer of higher conductivity. On the other hand, the presence of a lower layer with lower conductivity results in an increase of the peak value of the underground horizontal electric field. © 1964-2012 IEEE.
Yanallah K.,Universite Ibn Khaldoun |
Pontiga F.,University of Seville
Plasma Sources Science and Technology | Year: 2012
A semi-analytical model of a dc corona discharge is formulated to determine the spatial distribution of charged particles (electrons, negative ions and positive ions) and the electric field in pure oxygen using a point-to-plane electrode system. A key point in the modeling is the integration of Gauss' law and the continuity equation of charged species along the electric field lines, and the use of Warburg's law and the corona current-voltage characteristics as input data in the boundary conditions. The electric field distribution predicted by the model is compared with the numerical solution obtained using a finite-element technique. The semi-analytical solutions are obtained at a negligible computational cost, and provide useful information to characterize and control the corona discharge in different technological applications. © 2012 IOP Publishing Ltd.