Entity

Time filter

Source Type

Ain Oussera, Algeria

Hayoune A.,Nuclear Research Center of Birine | Hamana D.,University of Mentouri Constantine
Materials Science and Engineering A | Year: 2010

The effect of cold deformation on the interaction between precipitation, recovery and recrystallization reactions in an Al-12. wt.% Mg alloy was studied by dilatometry and high-temperature X-ray diffraction. During continuous heating of cold deformed samples, the dilatometric curves present new dilatometric anomalies which change with increasing prior-deformation. The new dilatometric anomalies were identified by using in situ high-temperature X-ray diffraction and were ascribed to the precipitation/recovery or dissolution/recrystallization interactions. It is established that after small deformations, recovery occurs before as well as during precipitation. However, at high prior-deformation, because of the high density of dislocations, precipitation becomes faster and competes with recovery. In both cases, the effect of recovery is not important in beginning of the process due to the interaction between dislocations and Mg atoms and it becomes more important after the reduction of Mg content and when the precipitates are coarsened and their interparticle spacing is increased. The formation of a new texture during recrystallization process can produce an increasing of the thermal expansion coefficient. © 2010 Elsevier B.V. Source


Chennai S.,Nuclear Research Center of Birine
Periodica Polytechnica, Electrical Engineering | Year: 2016

This paper present simple fuzzy control approaches for shunt active power filter based on five-level (NPC) inverter which can mitigate current harmonics generated by nonlinear loads and compensate reactive power. Today, five-level inverter is strongly used in the medium and high voltage applications; these advantages are low harmonic distortions, low switching losses, low electromagnetic interference and low acoustic noise. Second, fuzzy logic techniques have been successfully employed in several power electronic applications. To benefit from these advantages a novel control scheme based on fuzzy current controller is adopted; it is designed to improve compensation capability by adjusting the current error using a fuzzy rule. The reference current signals required to compensate harmonic currents use the synchronous current detection method, this technique is easy to implement and achieves good results. To maintain the dc voltage across capacitor constant and reduce inverter losses, a proportional integral voltage controller is used. The simulation of global system control and power circuits is performed using Matlab-Simulink and SimPowerSystem toolbox. The results obtained in transient and steady states under various operating conditions show the effectiveness of the proposed shunt active filter based on fivelevel (NPC) inverter using fuzzy control. Source


Salim C.,Nuclear Research Center of Birine | Toufik B.M.,University Mohamed Khider of Biskra
International Journal on Electrical Engineering and Informatics | Year: 2014

This paper presents a shunt active power filter performances based on threelevel (NPC) inverter using conventional pulse width modulation (PWM) and Ann's controllers to mitigate current harmonics generated by non-linear loads. Shunt APF is the best solution to eliminate harmonics drawn from nonlinear load especially for low power system, the conventional scheme based on the two level inverter controlled by hysteresis controller presents several drawbacks such us high inverse voltage applied to power components, degraded output voltage inverter waveforms, etc. Today three-level (NPC) inverter and intelligent controllers are widely used in different industrial applications. To take advantages of these inverter topology and artificial intelligent controller performance a novel control scheme based on Ann's current controller is proposed in this work. The control strategy adopted is the synchronous current detection method, it is easy to implement and permits a good extraction of reference currents compensation. The numerical simulation is performed using MATLAB-Simulink and SimPowerSystem Toolbox. The simulation results obtained in steady and transit states show the effectiveness and the superiority of Ann systems compared to PWM controller. Source


Hamidatou L.A.,Nuclear Research Center of Birine | Dekar S.,Ferhat Abbas University Setif | Boukari S.,Ferhat Abbas University Setif
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2012

Different types of synthetic multi-element standard material (SMELS) and four IAEA reference materials, 140, Sl-1, Soil-7 and Lichen-336 were analyzed for validation and QC/QA of the k 0-standardised Neutron Activation Analysis (k 0-NAA). The samples of SMELS and RMs were irradiated at Es-Salam research reactor and measured on an absolutely calibrated HPGe detector with 35% relative efficiency connected to a Canberra Genie 2k inspector. Concentrations of 33 elements such as As, Au, Ba, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, In, K, La, Mn, Mo, Na, Nd, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, Tm, U, Yb, Zn, and Zr were determined in SMELS and RMs. The analytical results agreed well with the assigned values of SMELS and certified values of RMs. In the case of RMs, concentrations of a few elements, whose certified values are not available, could be determined. The comparison between experimental values and assigned/certified data for SMELS and RMs was made by means of the results from Relative Bias, Z-score and U-score. The relatives bias of the elements determined in SMELS with respect to the assigned values were all within±4.6%. For RMs with respect to certified values were within±10% except for few elements for which RB varied from -28.6% to 12.8%. The Z-score values at 95% confidence level for most of the elements in both the materials were within ±1. The U-scores for most of the elements were lower than 1. © 2012 Elsevier B.V. All rights reserved. Source


Chennai S.,Nuclear Research Center of Birine
Revue Roumaine des Sciences Techniques Serie Electrotechnique et Energetique | Year: 2014

A three-phase three-level (NPC) shunt active power filters controlled by different controllers which can compensate current harmonics generated by nonlinear loads is presented in this paper. Three-level inverters and intelligent controllers have been successfully employed in several power electronic applications these past years. An ANN and fuzzy current controllers are adopted for three-level (NPC) shunt APF to improve the performances of the conventional control scheme. These controllers are proposed to simplify the complicated conventional hysteresis controller and to improve compensation capability of APF. The reference current signals required to compensate harmonics use the synchronous reference current detection method. This technique is easy to implement, require few calculations and achieves good results. To maintain the dc voltage across capacitor constant and reduce inverter losses, a proportional integral voltage controller is used. The simulation is performed using Matlab-Simulink and SimPowerSystem toolbox. The results obtained in transient and steady states under various operating conditions show the effectiveness of the proposed shunt APF based on these intelligent current controllers compared to the conventional scheme. Source

Discover hidden collaborations