Liste des publications
Fuzzy controller design using particle swarm optimization for photovoltaic maximum power point tracking
Recently, researchers have strongly promoted the use of solar energy as a viable source of energy due to its advantages and which it can be integrated into local and regional power supplies. The P-V curve of photovoltaic system exhibits multiple peaks under various conditions of functioning and changes in meteorological conditions which reduce the effectiveness of conventional maximum power point tracking (MPPT) methods and the Particle Swarm Optimization (PSO) algorithm is considered to be highly efficient for the solution of complicated problems. In this paper, the application of this approach based MPPT algorithm for Photovoltaic power generation system operating under variable conditions is proposed to optimize and to design an intelligent controller comparing to conventional one. Voir les détails
Mots clés : PV systems, Boost, PWM, MPPT, FLC, PSO
Purification and detoxification of petroleumrefinery wastewater by electrochemical process
The treatment of synthetic oily wastewater having the characteristics of a typical petrochemicalwastewater (PRW) by electrocoagulation (EC) using iron and aluminum electrodes was conducted inan electrolytic reactor equipped with fluid recirculation. During the treatment, the emulsion stabilitywas followed by the measurement of Zeta potential and particle sizes. Effects of some operatingconditions such as electrodes material, current density and electrolysis time on removal efficiencies ofturbidity and chemical oxygen demand (COD) were investigated in details. The PRW purification byEC process was found most effective using aluminum as anode and cathode, current density of 60A/m2 and 30 min of electrolysis time. Under these conditions, the process efficiencies were 83.52%and 99.94% respectively for COD and turbidity removals which correspond to final values of 96 mgO2/L and 0.5 NTU. A moderate energy consumption (0.341 kWh) was needed to treat 1 m3 of PRW.Besides, the ecotoxicicity test proved that toxic substances presented in the PRW, and those inhibitingthe germination growth of whet, were eliminated by the EC technique. Voir les détails
Mots clés : petroleum wastewater purification, electrocoagulation, energy consumption, ecotoxicity test.
Gap states density measurement in copper oxide thin films
The density of gap states near the Fermi level have been measured in copper oxide (CuO) thin ?lms deposited by spray pyrolysis technique. The measurement method is based on the exploitation of the current–voltage characteristics of the space charge limited current (SCLC) measured in a sandwich Au/CuO/Au structure. The measured gap states density is equal to 1.5x1014cm-3 and 2.0 x1014 ev-1 respectively in films prepared at 300 and 400 °C substrate temperature, while the defect position are located at 16 and 20meV above Fermi level. The carriers mobility and concentration are also determined from SCLC, the obtained results are in good agreement with Hall effect measurement ones. Voir les détails
Mots clés : Density of states Thin ?lms Spray pyrolysis Solar cells
Mechanical and Metallurgical Characterization of HSLA X70Welded Pipeline Steel Subjected to Successive Repairs
The aim of this work is to study the influence of successive weld repairs on the microstructure and themechanical behavior of the heat-affected zone (HAZ) of an HSLA X70 steel. Detailed microstructural examinationcombined to grain size measurement showed that beyond the second weld repair, the microstructure of the HAZ undergoessignificant change in the grain morphology and grain growth. The results of the X-ray diffraction analyzed using MAUDsoftware indicated an increase in the crystallite size and a decrease in the dislocation density according to the number ofweld repair operations. Consequently, a loss of mechanical properties, namely the yield strength and the toughness with thenumber of weld repairs, was recorded. Beyond the second weld repair operation, the properties of the welded joint do notfulfill the standards applied in piping industry. Voir les détails
Mots clés : HSLA X70 steel; Successive weld repair; Heat affected zone; Dislocation density
Sulfide precursor concentration and lead source effect on PbS thin flms properties
Lead sul?de (PbS) thin ?lms were synthesized using chemical bath deposition (CBD). Bath solutions are formed of various concentrations of thiourea, sul?de source, ranged from 0.6 to 1.2 M and two different salts as Pb source (lead acetate and lead nitrate). From the growth mechanism, we inferred that PbS is formed through the ion by ion process when using acetate lead source, while, using nitrate source yields to ?lms growth through the complex decomposition process. Due to the difference in the involved growth process, lead acetate produces ?lms with larger crystallite size (from 4 to 16 nm), smooth and dense ?lms. However, lead nitrate produces rough ?lms with smaller crystallite size (from 1 to 4 nm).Increasing the thiourea concentration results in crystallinity improvement when using lead acetate and, oppositely, in crystallinity degradation when using lead nitrate. Due to the quantum effect caused by the small crystallite sizes, the ?lms optical gap is varied from 0.5 to 0.9 eV. Voir les détails
Mots clés : Thin ?lms Lead sul?de Chemical bath deposition
Characterization of diatomitefrom Sig region (West Algeria)for industrial application
Diatomite also known Kieselguhr, is a non-metallic mineral composed of the skeletalremains of microscopic single-celled aquatic algae called diatoms. The purpose of this paper is to testand to evaluate the diatomite of Sig region (West Algeria) to substitute the main mould powder used incontinuous casting of steel for thermal insulation and lubrication.Design/methodology/approach – To assess the behavior of diatomite at different temperatures,a combination of simultaneous scanning calorimetric and thermogravimetric testing was used and toevaluate the structure of diatomite, the scanning microscopy method was applied.Findings – The results showed different endothermic and exothermic peaks, mainly at 84.7°C and783.5°C for endothermic peaks and 894.9°C for exothermic peak. The scanning microscopy methodwas used and a large porosity was observed. The trial industrial in continuous casting of steel showeda weak loss temperature of steel.Originality/value – This product may be used for thermal insulation in continuous casting of steel.Also the characterization showed the hot behavior of this product with the various transformationsand could give the possibility to other use Voir les détails
Mots clés : diatomite, fluorine, lubrication, Mould fluxes, thermal insulation
Evaluation and Chemical Analysis of Particulate Pollution in the Ironworks Site of El-Hadjar
The air that we breathe today is a mixture more or less polluted by location where we are. This mixture of pollutants generating significant and sustainable threats to human health, especially respiratory problems .The environmental concern is becoming increasingly strong, driven in particular by the current debate on sustainable development that is mirrored various international conferences [1] .Also theeffectson a global scale are warming the atmosphere and therefore the Earth, or the destruction of the ozone layer. The air quality management contributes to the mastery of a better knowledge of the pollution generated by the steel industrial activity. This investigation is the first national enterprise approach to the management of environmental problems on an industrial scale, more particularly in the steel sector. Taking into account these principles, it is appropriate to follow the pollution by suspended particles in and around the steel complex of El Hadjar.The objectives of this work are:Knowledge Of highest concentration level of dust inside and outside the workplace. Evaluation Compared to WHO limits values [2] and European Directives [3];[4]. Determination Of heavy metals in dust fallout.For the choice of measurement sites, a clipping entire surface of the steel complex was carried out by a method called mesh. This method we devoted 19 measurement sites. The sampling method used is that of BERGHEROFF. Indicators are the overall amount of dusts deposited chemical analysis elements such as Cr, Cu, Zn, Ni, Pb and Mn [4]. The quantities of dust are analytically weighed and then analyzed atomic absorption analytical chemistrySuspended particles that contaminate the air are the main carriers carry in the wind various polluting compounds (SO2, Cu, Pb, H2SO4, NH3 ...) [3]. At PMA 2, calculations show is discharged 4509 m3 per ton of fumes sinter. The results showed measurement sites S2, S3, S4, S5 and S18 are large emissions dusts. These sites except S18 represent the hot zone of complex. According Opair,the incidence of values of the measured dust on the sites is all above the limit value. For heavy metals in the dusts, there is a high concentration of zinc in all sites. Knowing that is neurotoxic and carcinogenic Pb is present in large quantities with a peak in S3. For S11 and S17 its value is close to the norm. The chromium and nickel both carcinogenic move in the same direction with alarming values. Voir les détails
Mots clés : Air pollution, dust emission, particulate fallout, TPS, method Bergeroff, heavy metals.
WAVELETS AND PRINCIPAL COMPONENT ANALYSIS METHOD FOR VIBRATION MONITORING OF ROTATING MACHINERY
Fault diagnosis is playing today a crucial role in industrial systems. To improve the reliability, safety and efficiency advanced monitoring methods become increasingly important for many systems. Vibration analysis method is essential in improving condition monitoring and fault diagnosis of rotating machinery. Effective utilization of the vibration signals depends upon the effectiveness of the applied signal processing techniques. In this paper, fault diagnosis is performed using a combination between Wavelet Transform (WT) and Principal Component Analysis (PCA). The WT is employed to decompose the vibration signal of measurements data in different frequency bands. The obtained decomposition levels are used as input to the PCA method for fault identification using respectively, the Q-statistic, it is also called Squared Prediction Error (SPE), and the Q-contribution. Clearly, useful information about the fault can be contained in some levels of wavelet decomposition. For this purpose, Q-contribution is used as an evaluation criterion to select the optimal level, which contains the maximum information. Associated to spectral analysis and envelope analysis, it allows clear visualization of fault frequencies. The objective of this method is to obtain the information contained in the measured data. The monitoring results using real sensor measurements from a pilot scale are presented and discussed. Voir les détails
Mots clés : vibration, Fault Diagnosis, Wavelet Analysis, principal component analysis, squared prediction error
First-principles investigation of the optical properties for rocksalt mixed metal oxide MgxZn1-xO
In this paper, we have presented a theoretical study of the optical properties for the cubic MgxZn1-xO(x = 0.0, 0.125, 0.375, 0.625, 0.875 and 1.0) alloys using the full-potential linearized augmented planewave (FP-LAPW) method based on the density functional theory (DFT). The local density approximation(LDA) was applied to calculate the structural properties. In order to explore the desired properties, the MgxZn1-xO alloys were modeled at various x compositions from 0.0 to 1.0 by step of 0.125. The recentlymodified semi-local Becke-Johnson potential with LDA correlation in the form of mBJ-LDA was used topredict the energy band gap, optical dielectric function, refractive index, absorption coefficient, reflectivity,optical conductivity and the electron energy loss of MgxZn1-xO alloys. The obtained results show good agreement with the experimental data, which indicate that the investigated ternary alloys areamong promising material for the fabrication of electronic, optoelectronic devices and their applications. Voir les détails
Mots clés : alloys, Electronic materials, Optical materials, Ab initio calculations, Band-structure
UPFC Device: Optimal Location and Parameter Settingto Reduce Losses in Electric-Power Systems Using a Genetic-algorithm Method
Ensuring the secure operation of power systems has become an important and critical matter during the present time, along with the development of large, complex and load-increasing systems. Security constraints such as the thermal limits of transmission lines and bus-voltage limits must be satisfed under all of a system’s operational conditions. An alternative solution to improve the security of a power system is the employment of Flexible Alternating-Current Transmission Systems (FACTS). FACTS devices can reduce the flows of heavily loaded lines, maintain the bus voltages at desired levels, and improve the stability of a power network. The Unifed Power Flow Controller (UPFC) is a versatile FACTS device that can independently or simultaneously control the active power, the reactive power and the bus voltage; however, to achieve such functionality, it is very important to determine the optimal location of the UPFC device, with the appropriate parameter setting, in the power system. In this paper, a genetic algorithm (GA) method is applied to determine the optimal location of the UPFC device in a network for the enhancement of the power-system loadability and the minimization of the active power loss in the transmission line. To verify our approach, simulations were performed on the IEEE 14 Bus, 30 Bus, and 57 Bus test systems. The proposed work was implemented in the MATLAB platform. Voir les détails
Mots clés : FACTS, UPFC, GA, loadability, Matlab