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Search Results: 1 - 10 of 543529 matches for " M.R. Mekideche "
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A New Direct Torque Control Method for Switched Reluctance Motor Drives Compared with Vector Control
M. Hadef,T. Rekioua,M.R. Mekideche,D. Rekioua
Asian Journal of Information Technology , 2012,
Abstract: In this study, Direct Torque Control (DTC) and vector control of Switched Reluctance Motor (SRM) drives are proposed. In DTC scheme, current controllers followed by Pulse Width Modulation (PWM) or hysteresis comparators and coordinate transformations are not used. A position sensor is used at starting, to know the approximate rotor position. This study proposes a comparison between DTC and vector control of SRM. The simulation results prove the feasibility of the proposed direct torque control as compared with vector control.
Parameter Identification of a DC Motor Using Moments Method
M. Hadef,A. Bourouina,M.R. Mekideche
International Journal of Electrical and Power Engineering , 2012,
Abstract: Time moments have been introduced in automatic control because of the analogy between the impulse response of a linear system and a probability function. This basic idea has generated applications in identification, model order reduction and controller design. In this study, a newly developed identification algorithm, called moments method, is introduced and applied to the parameter identification of a dc motor. The simulation and experimental results are presented and compared.
MLP Neural Network and FEM for the Inverse Problem of Parameters Identifications
T. Hacib,M.R. Mekideche,N. Ferkha
International Journal of Electrical and Power Engineering , 2012,
Abstract: This study presents an approach which is based on the use of supervised feed forward neural network, namely Multilayer Perceptron (MLP) neural network and Finite Element Method (FEM) to solve the inverse problem of parameters identification. The approach is used to identify unknown parameters of ferromagnetic materials. The methodology used in this study consists in the simulation of a large number of parameters in a material under test, using the Finite Element Method (FEM). Both variations in relative magnetic permeability and electrical conductivity of the material under test are considered. Then, the obtained results are used to generate a set of vectors for the training of MLP neural network. Finally, the obtained neural network is used to evaluate a group of new materials, simulated by the FEM, but not belonging to the original dataset. Noisy data, added to the probe measurements is used to enhance the robustness of the method. The reached results demonstrate the efficiency of the proposed approach and encourage future works on this subject.
Numerical Comparison Between Electromagnetic Forces Calculation Methods
A. Rezig,N. Ikhlef,M.R. Mekideche
International Journal of Electrical and Power Engineering , 2012,
Abstract: To calculate magnetic global force on bodies several approaches can be used with the Finite Element Method (FEM). They are based on Maxwell`s stress tensor, or on the Lorentz formula or on the virtual work principle. The accuracy of the results for a given mesh is an important criterion for choosing between them. Description and comparison of these methods applied to the calculation of magnetic global forces on current carrying conductor is done.
Axial Magnetic Forces Comparison in Linear and Nonlinear Model of Ferromagnetic Core of Magnetic Actuators
H. Allag,M.E.H Latreche,M.R. Mekideche,N. Ikhlef
Journal of Engineering and Applied Sciences , 2012,
Abstract: Several works were developed for local and global magnetic force calculation, this works are based on different theories such as a simplified magnetisation model and energy approach, generally this models are applicable for a ferromagnetic materials considering their linear comportment, or in reality the magnetisation phenomena (saturation phenomena) of these materials make possible to take into account a non-linear model known as the Hysteresis model In this study we present the method of Maxwell stress tensor and its application in ferromagnetic material calculation using the model of Preisach Hysteresis which will be integrated to 2D FEM calculation code For a simulation result we use two axisymetrical actuators from which the essential curves are presented such as the force time variation, the mechanical behaviour (displacement) and the magnetic quantities (magnetic field, magnetic induction).
Situation Cavity Effect on Power Absorbed by Plasma Microwave
N. Ikhlef,A. Rezig,M.R. Mekideche,O. Leroy,P. Leprince
Journal of Engineering and Applied Sciences , 2012,
Abstract: We present in this study a 3D numerical modelling of a microwave discharge (2.45GHz) excited by a surface wave in a large and small diameter cylindrical plasma cavity. Our first studies have been focused on the influence of the vertical situation of a short circuit in order to optimize the power coupling in the discharge. We used the CST microwave studio commercial code which solves Maxwell equations using the Finite Integration Technique (FIT).
Short Term Effect of Consolidation on Profitability of Nigerian Banks
M.R Sanni
African Research Review , 2010,
Abstract: Has the 2006 consolidation of banks in Nigeria led to a significant change in the profitability [Earning Per Share (EPS)] of the banks? This paper examined the EPS of 13 out of the 25 post consolidation ‘mega’ banks. The banks examined are those that fairly retained their identities before and after the consolidation exercise. The three-year (2003-2005) pre consolidation EPS mean of the banks was compared with the three-year (2006-2008) post consolidation period. Using descriptive statistical method, the combined EPS of the banks changed but not significantly at 5% significant level when a paired sample t-test statistical method was used. Three of the banks however stood out. The change (an increase) in the EPS of two of them is significant while the change (a decrease) in the third one is also significant not only at 5% but at 1%. The findings here confirm the existing controversy on whether or not mergers or acquisitions lead to improved profitability. What is however clear is that barring any effect of the present global economic meltdown; it may take some time for the EPS of most of the banks to change significantly. Key Words: EPS Profitability Consolidation
Information and communication technology products: their gains and pains on Nigerian banking system
M.R Sanni
African Research Review , 2009,
Abstract: Year 2006 witnessed a banking revolution in Nigeria as the minimum paid up share capital of Nigerian banks was increased from N2 billion to N25 billion. With it came consolidation and stiff competition among the emerging “mega” banks resulting into investments in ICT. This paper considers the positive as well as the negative sides of some ICT products like ATM, e-banking, e-payment and e-commerce among others. It compares the investment by banks in ICT in the last three-years with the volume and value of banking transactions occasioned by such investment. It also considers savings from forgeries and frauds and concludes that the gains from ICT banking products far outweigh their shortcomings.
Oscillatory Gas Flow in a Circular Nanotube
M.R. King
The Open Nanoscience Journal , 2007, DOI: 10.2174/1874140100701010001]
Abstract: Gas flow through nanoscale conduits shows distinctly different physics compared to flow at the macroscale. One of the first manifestations of this is the appearance of wall slip. Here we consider the oscillatory flow of an incompressible Newtonian gas through a circular nanotube, with first order wall slip due to rarefaction. It was found that the major effect of wall slip at lower oscillation frequencies is to alter the instantaneous velocity profiles from Poiseuille-like to more plug-like, with an overall enhancement to the fluid velocity magnitude. However, at higher frequencies the enhancement to velocity magnitude due to wall slip is greatly diminished, and rarefaction introduces a region of backflow near the centerline of the nanotube. These flow characteristics may have important implications for the design of various practical applications of unsteady gas flow through nanoscale conduits, from fuel cell membranes to gas-powered nanomachines constructed from carbon nanotubes.
First Principles Studies of the Effect of Nitrogen Impurities on the Energy Gap of Rutile TiO2-xNx by Pseudopotential Approaches
M.R. Benam
Journal of Engineering and Applied Sciences , 2012, DOI: 10.3923/jeasci.2011.18.20
Abstract: We have studied the electrical properties of rutile TiO2-xNx compound which x is the fraction of Ni impurities and was chosen to be 0.0625, 0.125, 0.25 and 0.5. In the calculations, we have adopted a pseudopotential and supercell approach based on the Density Functional Theory (DFT) with GGA approximation for the Exchange-correlation potential as implemented in SIESTA code. We have calculated the band structure and Density of State (DOS) and therefore, the changes of the energy gap of this compound with nitrogen substitution in oxygen sites. The quality of the used pseudopotential was tested by comparing the calculated band structure and DOS using Full Potential Linear Augmented Plane Wave (FP-LAPW) and pseudopotential methods. The result shows that the energy gap of TiO2-xNx has decreases considerably due to the appearing of the N-2p orbitals in the bottom of the energy gap which is in good agreement with the recent experimental researches about the red shift of the threshold absorbance frequency of this compound which has made it an interesting photocatalysis in the visible spectrum of the solar radiation.
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