Liste des documents
Pipelines Corrosion Due to the Electromagnetic Pollution caused by the High Voltage Power
This paper studies the effect of the electromagnetic pollution caused by the high voltage power lines on the corrosion of the buried pipeline. In this objective, the finite element method (FEM) was used to calculate the magnetic field distribution and the induced current densities in the buried pipeline caused by both horizontal and vertical configuration of the HVPL during steady state conditions. In order to diagnose the effect of the electromagnetic pollution on the corrosion of the pipeline, the electrochemical impedance spectroscopy (EIS) measurements were used to characterize the corrosion polarization properties of X70 steel in simulated soil at various AC current densities. The results show that, the electromagnetic pollution caused by the high voltage power lines affect the electrochemical characteristics of the X70 steel pipeline and accelerate the corrosion of the pipeline. Voir les détails
Mots clés : Electromagnetic pollution, high voltage power line, induced current density, X70 steel pipeline, corrosion, Finite Element Method, electrochemical impedance spectroscopy.
Application of Diagonally Relaxed Orthogonal Projections (DROP)- conjugate gradient and Kaczmarz method for X Rays reconstruction image
In this work, we present the application of algorithms based on algebraic methods, ray tomography image reconstruction X. So DROP algorithms with quadratic regularization (orthogonal projections Relaxes diagonal), conjugate gradient and Kaczmarz will be implemented and applied to real images obtained by an X-ray tomography, a comparative study was made in order to examine the reconstruction algorithms results Voir les détails
Mots clés : DROP method, regularization, Tomography, Kaczmarz method
ETUDE ET DÉVELOPPEMENT D’UNE TECHNIQUE DEFILTRAGE BASÉE SUR L’ACPAPPLICATION SUR LES INTERFÉROGRAMMES INSAR
Les interférogrammes dans un processus interférométrique sont souvent bruités, ils présentent desdiscontinuités au niveau des franges ; qui sont due principalement à la décorelation spatiale,temporelle, et thermique, en plus des erreurs de recalage des couples interférométriques. Plusieursméthodes de filtrage ont été développées. Dans ce travail nous sommes particulièrement intéressé auxtechniques de filtrage interférométrique basées sur la décomposition en sous espaces dont nous avonsproposé une méthode de sélection de sous espace optimal afin de conserver l’information physiqueparticulièrement au niveau des zones de transitions des franges. La méthode a été testée sur desinterférogrammes de zones accidentées. Les résultats obtenus sont comparés aux résultats de filtragepar les algorithmes de Goldstein et vecteur Voir les détails
Mots clés : processus interférométrique, interférogrammes, décorrélation spatiale, sous espace optimal, transitions des franges
Simulation of the propagation of cracking by finite element code calculation of a supermartensitic stainless steel pipe
The biggest concern of industrial manufacturers is the sustainability of their equipment and facilities. In the oil sector, for example, cylindrical pipe for the energy transportation to suffer corrosion damage or corrosion stress cracking is a complex problem since it requires to follow the geometry of the crack over time. Many numerical methods are applied to the propagation of fatigue cracks that require conditions to correct limitations in loading term to get results close to reality.The method of Finite Elements is a way to simulate crack propagation. However, it presents two major difficulties, the first is the use of a very fine mesh around the crack tip and the second difficulty is the explicit representation of the crack that the problem of cracking path during the simulation of propagation. Indeed, let the mesh is constructed with a priori knowledge of the route or it is changed every time the crack advance.In this context, we studied law cracking of internal pressure pipe of super martensitic stainless steel 13% Cr and 5% Ni 2% Mo by a simulation using a finite element code "ANSYS " with a calculation of the stress intensity factor and prediction of the lifetime. Voir les détails
Mots clés : simulation, Finite Elements, Crack, Pipe, Super Martensitic Stainless Steel.
Etude des proprietés structurales , élastiques et électronique de CuS et CuTe par la méthode FP-LMTO
The aim of this work is to study the structural ,electronic and elastic properties of CuS. for this, we use the full-potential linear muffin-tin orbital (FP-LMTO) method in the framework of density-functional theory (DFT). The exchange and correlation energy is described in the generalized gradient approximation (GGA ) using Perdew-Wang parameterization. We have investigated the effect of composition on structural properties such as lattice constants, bulk modulus and band gap. We report the results concerning the variation of thegaps and crossover of the direct, indirect band gap and bowing .Finally, a reasonable agreement is found from the comparison of our results with other theoretical calculations. Voir les détails
Mots clés : CuS, FP-LMTO, electronic properties, elastic proprieties
Elaboration and characterization of a piezoelectric ceramic resonator
In this work. We Synthesized PbTiO3 from PbO and TiO2 oxides from Solid state reaction and we studied the development and manufacture of solid piezoelctrique resonator of PT .We played on parameter as sintering time. We used XRD and SEM for morphological characterization and Analyzer for impedance piezoelectric characterization. Voir les détails
Mots clés : PT, ferroelectric, resonator, impedance, XRD, SEM
Morphology and Mechanical properties of α-grain boundary in Ti-6Al-4V TIG welds.
In this Work, the effect of the TIG Welding process on the Morphology and mechanical behavior of α grain boundary (α-GB) phase appearing in TA6V welds are investigated. Different morphologies are observed depending on the pulsed frequency parameter, namely, the Zig-Zag morphology, the saw-teeth morphology and the normal continuous layer. The micro-hardness of each morphology has been measured and discussed. Voir les détails
Mots clés : TA6V, TIG Welds, α-Grain Boundary, Microhardness
INFLUENCE OF ALLOYING ELEMENTS OF WELD METAL ON MECHANICAL BEHAVIOR OF HSLA-X70 WELDS
In the pipeline industry, the alloying elements are continually evolving as a function of weldability and reliability of steels. For this reason, metallurgists discover and develop every day new base materials like HSLA steels and efficient electrodes. We propose in this work to study the influence of chromium and molybdenum in C-Mn filler metal, hoping to demonstrate their microsturctural evolution and mechanical behavior on welds of high strength steels HSLA-X70. The mechanical properties included hardness, impact and tensile strength was investigated. The results show that, optimal properties of welds correspond to the existence of both molybdenum and chromium in weld metal with proportions varying between 1% and 2.5%. Voir les détails
Mots clés : alloying element, Weld metal, HSLA-X70, TIG welding, mechanical behavior
Protection d’un acier au carbone contre la corrosion acide par un inhibiteur vert
En termes de protection, les inhibiteurs constituent un moyen pratique et économique pour lutter contre la corrosion. Cependant, la mise au point d’inhibiteurs de corrosion non toxiques et biodégradables devient un enjeu primordial. Les extraits de plantes sont devenus importantes comme source d’inhibition écologiquement acceptable, facilement disponible et utilisable pour une vaste gamme de prévention de la corrosion. L'objectif de ce travail consiste à étudier l'action inhibitrice d’une substance verte et naturelle à base de plante, sur le comportement à la corrosion de l’acier au carbone X 70 largement utilisé dans la construction des pipelines, dans HCl 1M, en utilisant différentes techniques électrochimiques. Les résultats obtenus montrent que l’inhibiteur est doté d’un pouvoir inhibiteur appréciable, et le caractère dominant dans notre cas traduit une cinétique de transfert de charge. Voir les détails
Mots clés : acier, corrosion, plante, techniques électrochimiques, efficacité inhibitrice.
Comparative Performance Study between DTC_C and DTNC Multi-level Inverter Fed DSIM
A comparative performance study between the classical direct torque control (DTC_C) and that of a direct torque control improved by applying the technique of artificial intelligence based on the neural network (DTNC) is proposed in this paper. The command is applied to a double-stator induction machine (DSIM) fed by a multi-level inverter. Simulation results of the speed control of the machine and the improvement of the torque and the flux by reducing the fluctuations are studied by illustrating the DTNC merits compared to the classical DTC_C. Voir les détails
Mots clés : A double-Stator Induction Machine, Direct Torque Control, Neural Network, Multi-level Inverter.