Liste des publications
AC Corrosion Induced by High Voltage Power Line on Cathodically Protected Pipeline
The implications of the influence of alternating currents on buried pipelines are of great concern to all pipeline owners in world. The relevance of the interference is always increasing for operational personnel and for the protection of buried metallic structures from corrosion. The paper studies the electromagnetic interference problem between an existing high voltage power line and a newly designed underground pipeline cathodically protected. Induced voltages and currents are evaluated for steady state operating conditions of the power line. It is found that on pipelines suffering from A.C. interference traditional pipe-to-soil potential measurements do not guarantee efficient cathodic protection against corrosion. A specific approach to assess the effectiveness of cathodic protection should be adopted. Voir les détails
Mots clés : Induced Voltages, Electric Power Transmission Lines, pipeline, AC Corrosion, cathodic protection, soil resistivity, AC interference
Discoloration of Azo Dye Solutions by Adsorption on Activated Carbon Prepared from the Cryogenic Grinding of Used Tires
This present work reports a study about the adsorption of cationic dye (Methylene blue) by activated carbon prepared from the cryogenic grinding of used tires. Characterization of the obtained activated carbon by chemical analysis, FTIR and SEM, was studied and resumed that the activated carbon was mesoporous. The effect of various experimental parameters such as contact time, solution pH, adsorbent dose and dye concentration, on the dye adsorption uptake on the activated carbon has been investigated using batch adsorption experiments. According to the experiments results, it was shown, that equilibrium was achieved in less than 114 min. The effect of pH investigated for values ranging from 2 to 11, showed maximum adsorption for pH 11. The equilibrium adsorption isotherms models of Langmuir, Freundlich and Dubinin-Radushkevich, were tested for the quantitative description of the dye adsorption. The Langmuir isotherm provided the best fit for dye adsorption onto the prepared activated carbon and the maximum adsorption capacity was found to be 30.21 mg.g-1. The results show that the produced activated carbon from used tire is an alternative low-cost adsorbent for removing dyes from solutions. Voir les détails
Mots clés : adsorption, FTIR, SEM
Effect of Biobased Plasticizers on Thermal, Mechanical, andPermanence Properties of Poly(vinyl chloride)
Phthalates can be replaced by other harmless andenvironmentally friendly plasticizers, such as isosorbidediesters (ISB), and epoxidized sunflower oil (ESO),which has been proved an efficient stabilizer for poly(vinyl chloride) (PVC) in helping to prevent degradationduring processing. Formulations based on PVC withdifferent amounts of ISB, ESO, and di-(2-ethylhexyl)phthalate (DEHP) from 0 to 60 parts by weight per hundredparts of resin were realized. To make PVC flexiblewith partial amounts of the debated phthalates asplasticizers, we use a combination of DEHP, ISB, andESO. Effects of these two biobased plasticizers, ISBand ESO, and their mixture with DEHP on thermal stabilityby measuring discoloration degrees and thermalgravimetric analysis, on mechanical properties suchtensile strength, elongation at break, and hardness,were characterized. Plasticizer permanence propertiesof PVC compounds were studied. Studies showed thatprocessibility and flexibility were improved by the additionof a plasticizer system (ISB, ESO, and DEHP). Anincrease in the content of ISB and/or ESO increasedthermal and mechanical properties, whereas compositionswith ternary compositions of ISB/ESO/DEHP (15/15/30) exhibited the best performance properties. Voir les détails
Mots clés : PVC, Sunflower oil, Leaching, Volatility
Simulation & Expérimentation en Soudage Etude du Comportement Thermique et Mécanique des Métaux à Usage Aéronautique.
La mise en œuvre de nouvelles techniques d’assemblage, en remplaçant le rivetage par le soudage, permet l’allègement des structures et des appareils à usage aéronautique. Dans le présent travail, l’intérêt est porté sur l’étude de deux procédés de soudage importants et récents qui sont le soudage par friction malaxage FSW et par l’arc électrique TIG. Dans un premier temps, une étude du comportement thermique de quelques métaux soudés par le procédé TIG, est menée. Une modélisation et des simulations numériques du transfert thermique sont réalisées, mettant en évidence l’apparition des zones à risques et l’effet des différents paramètres de soudage. Une étude expérimentale du soudage est ensuite présentée permettant une validation des résultats numériques. Dans un second temps, la conception et la réalisation d’un outil de soudage par friction malaxage FSW (Brevet 2007) sont effectuées. Des essais de soudage ont été menés par la suite avec succès. Les cordons de soudure obtenus par ces deux procédés ont été caractérisés par différentes techniques et leurs propriétés mécaniques ont été déterminées. Voir les détails
Mots clés : thermique, 3D, Essais mécaniques, acier, MEF, soudage TIG, soudage FSW, source de chaleur, alliage d’Aluminium
Extended Kalman Filter and Markov Chain Monte Carlo Method for Uncertainty Estimation. Application to X-Ray Fluorescence Machine Calibration and Metal Testing
This paper is concerned with a method for uncertainty evaluation of steel samplecontent using X-Ray Fluorescence method. The considered method of analysis is acomparative technique based on the X-Ray Fluorescence; the calibration step assumes theadequate chemical composition of metallic analyzed sample.It is proposed in this work a new combined approach using the Kalman Filter and MarkovChain Monte Carlo (MCMC) for uncertainty estimation of steel content analysis. The Kalmanfilter algorithm is extended to the model identification of the chemical analysis process usingthe main factors affecting the analysis results; in this case the estimated states are reducedto the model parameters. The MCMC is a stochastic method that computes the statisticalproperties of the considered states such as the probability distribution function (PDF)according to the initial state and the target distribution using Monte Carlo simulationalgorithm. Conventional approach is based on the linear correlation, the uncertainty budgetis established for steel Mn(wt%), Cr(wt%), Ni(wt%) and Mo(wt%) content respectively. Acomparative study between the conventional procedure and the proposed method is given.This kind of approaches is applied for constructing an accurate computing procedure ofuncertainty measurement. Voir les détails
Mots clés : Kalman filter, Markov Chain Monte Carlo, X-Ray fluorescence calibration and testing, steel content measurement, uncertainty measurement
Etude Comparative des Techniques de Filtrage Actif Sélectif par le Référentiel Synchrone de Park d-q et l’Approche FMV
To minimize the total harmonic distortion (THD) and improve the power factor (PF), this paper presents a comparative study between two techniques of shunt power active filter (SPAF) by a selective action of harmonics. These two techniques are based on the SAPF of certain low frequency harmonics (5th and 7th) whose identification of the harmonics of references of the first is made by the axis synchronous d-q of the Park, and the second is done by the approach of self-tuning filter (STF) Thereafter, The active simultaneously filtering of the 5th and 7th harmonics of the current of load catches. The shapes of the signals and the THD values resulting from the results of digital simulations (Matlab-Simulink) elaborate the effectiveness and the best technique of this type of filtering. Voir les détails
Mots clés : PF, THD, Harmonics, SAPF, STF, d-q Park Synchronous Axis
Ultra-wideband DRA Integrated with Narrow-band Slot Antenna
A new ultra-wideband (UWB) antenna integrated with a narrow-band (NB) antenna has been designed and fabricated. The UWB antenna consists of a U-shaped dielectric resonator fed by a microstrip line. In addition, the proposed structure integrates an NB slot with the same polarization. The electromagnetic analysis is carried out by using two commercial software tools. To validate the proposed concept, experimental measurements have also been performed. The measured results show that the dielectric resonator antenna (DRA) provides a wide bandwidth from 2.94 to 11.34 GHz (covering the UWB spectrum, 3.1–10.6 GHz) while the slot antenna provides a 2:1 voltage standing wave ratio bandwidth for 5.71–6.13 GHz. Moreover, the proposed design allows an efficient integration with very good isolation between the two ports (transmission coefficient S21 <−20 dB in the whole operating frequency band). Voir les détails
Mots clés : ultra-wideband (UWB) antenna, Integrated antenna, DRA
Acoustic emission signal denoising to improve damage analysis in glass fibre reinforced composites
In this contribution, continuous wavelet denoising technique is developed to enhancethe signal to noise ratio of acoustic emission (AE) signals. The time– frequency characteristics of the recorded noise are first determined by calculating the noisewavelet coefficients. Then, an algorithm able to proceed denoising by extracting noise features from those corresponding to AE signals is developed. The denoising procedure is applied to get meaningful signals when the detection threshold is decreased from 30 dB to 25 dB. Furthermore, the spectral flatness measure was applied to eliminate signals originating from noise. Experiments were conducted on cross-ply composite specimens [±45°]6S to examine the efficacy of the proposed technique. The denoised signals were analysed using the continuous wavelet transform and were also analysed in terms of the dominant frequency band which was processed by a fast Fouriertransform. Results show that denoised low-amplitude AE hits are well correlated withhigh-amplitude AE hits (A≥30 dB) in terms of damage characterisation. Voir les détails
Mots clés : acoustic emission, polymer-based composite, Denoising, Signal processing, damage characterisation
Trace and essential elements determination in baby formulas milkby INAA and k0-INAA techniques
As a part of the food analysis program executedat Es-Salam research reactor by neutron activation analysislaboratory, the concentration of As, Ba, Br, Ca, Fe, K, La,Rb and Zn in baby formulas milk have been determined byusing INAA and k0-NAA techniques. It was found that theconcentration of all elements obtained by both techniqueswas relatively identical for the three brands of the 0–6 and6–12 months of analyzed samples. In addition, the analyticalresults have been compared with those given byproducers. Voir les détails
Mots clés : Trace and essential elements, NAA method, Milk products, Analysis
Real Time Implementation of Shunt Active PowerFilter (SAPF)for Harmonic suppression and PowerQuality Improvement
In this paper, A Shunt Active Power Filter (SAPF) is implemented using a dSPACEDS1104 processor to compensate harmonics and reactive power produced by nonlinearload. The reference source current is computed based on the measurement of harmonicsin the supply voltage and load current. A hysteresis based current controller has beenimplemented in a DSP processor for injecting the compensating current into the powersystem, so that SAPF allows suppression of the harmonics and reactive power componentof load current, resulting in a supply current that is purely sinusoidal. Simulation andexperimental results of the proposed SAPF to meet the IEEE-519 standards are presented. Voir les détails
Mots clés : Harmonics, Power quality, Active power filter, hystérisis comparator, real time control