Liste des documents
Improving the Power Quality of the Arc WeldingSupply using an Active Power Filter
This paper presents a new circuit topology suitablefor arc welding inverter applications, this topology is based onshunt active power filter (APF), in order to improve the powerquality and reduced the total harmonic distortion (THD) byconsequently improve the power factor (PF), a modified activeand reactive power method (p-q),which is combined with aself-tuning filter, is used to identify the harmonics currentsreferences of the load current, Also a PI controller has beenused to maintain the level of DC-link voltage at a constantvalue and improves its dynamic response; the voltage sourceinverter of APF is controlled by hysteresis current controller.The Major favorable features of this topology like fastresponse to load and source voltage conditions will result inbetter welding performance. The performance of the entiresystem is evaluated on the basis of THD of the source current,input power factor, dynamic response, voltage regulation androbustness to prove its effectiveness in terms of excellent powerquality. Voir les détails
Mots clés : arc welding, Active power filter (APF), power factor (PF), total harmonic distortion (THD), modified active and reactive method (p-q)
Video Processing Software-based Pipeline Endoscopic Inspection
Currently, all the codes and the standards of the fluids transport industries require rigorous pipeline inspection, in order to detect all defects and anomalies and avoid leaks and failures. For this reason, a team within the division of Signal Processing and Imagery had as mission to develop an endoscope which can replace the operator inspection inside the pipeline and improve its quality and diagnostic. This endoscope named 'Pipe Explorer' is controlled by FPGA microcontrollers, and is equipped with a camera. While moving inside the pipe, the camera records a video on the memory card. In this way and in order to offer a practical tool to the operator, we have developed graphical software based on processing techniques of the stored video consisting in video preprocessing and segmentation. At the end of this processing, we obtain a video result on which appears the analysis and the interpretation of the original video to give an internal pipe quality diagnosis. The results shows all the defective areas such as corrosion which are stained with {green, blue, red} color according to its degree of severity and the risk of harmfulness on the inspected pipeline. Voir les détails
Mots clés : Pipeline inspection, endoscopy, video processing, video segmentation, corrosion.
Study and modelling of a microwave sensor tocharacterize a dielectric materials and for CNDapplications
Non-destructive testing is a science of evaluationvarious properties of materials, without compromising itsusefulness and use. These properties can be physical, chemical,mechanical or geometrical. There are several techniques of nondestructive testing such as: acoustic emission, penetrate testing,eddy current, ultrasound and radiography, ... . However, each ofthese methods has certain limitations and disadvantages. Sincethe 1970s, some researchers have tried to use microwavetechniques to detect possible surface cracks in metal components,volumic cracks in dielectric materials or to characterize adielectric material.The objective of this article is to present a method ofcharacterization of dielectric materials, by modeling a microwavesensor. A change in the resonant frequency of the microwavesensor resulting from a change in its effective dielectric constantis considered as an index to define the dielectric constant of thesample. This work was devoted to study, modelling andrealization of a micro strip structure by the method of moments,later this structure will be simulated by a numerical modellingsoftware HFSS (High-Frequency Structure Simulator) to confirmthe results and validate the model. Voir les détails
Mots clés : Non-Destructive testing, Microwave Techniques, HFSS, Microwave Sensor, Dielectric Constant, Micro strip Modelling, moment method
Characterization of local mechanical behavior of TA6V weld sheet
The present work aims to study the local mechanical behavior of TA6V weld sheet. To this purpose, X-ray Diffraction (XRD), optical microscopy and nano-indentation measurements have been employed. The results highlight strong relationship between the hardness (HIT), Young’s modulus (EIT) values and the microstructure of each zone and phase present along the weld joint. The HIT of the molten zone (MZ) is greater than that of the Heat affected zone (HAZ) and the base metal (MB) in the α phase, whereas it shows small values in the HAZ than that of MB in β phase. Voir les détails
Mots clés : TA6V, Nanoindentation, Microhardness, microstructure.
Evaluating the Flicker caused byElectric Arc Furnacethrough the Multi-scale Entropy MSE Algorithm SampEn
This paper presents a new method to evaluate the Arc voltage quality in electric arc furnace (EAF). It has been shown that is possible to allow the representation of nonlinear dynamics and coupling effects between different waves for irregularity of electrical signals issued by electrical components though multi-scale entropy algorithm SampEn. This work shows the behavior of the feature extraction with SampEn when it’s used to evaluate the signals that deviate the arc voltage in (EAF). Flicker effect with voltage imbalances are analyzed by means of the SampEn concept. Voir les détails
Mots clés : Entropy, Arc voltage signals quality, Flicker effect, voltage imbalance
Performance of some Variational ImplicitDeformable Models on Segmenting OpticalMicroscopy Images
Industrial micrographs are used to evaluate a steelsor alloys. This assessment consists of visualizing and describingthe basic element (at the nanoscale) constituting the material.The information provided by the micrographic images needto be highlighted by image processing methods. In this paperthe performance of some region-based variational models arepresented. Such study allows to choose best models that give themore accuracy segmentation in less processing time. Voir les détails
Mots clés : Material microstructures, Microscopy images, segmentation, deformable models, region-based active contours
Synthesis and characterization of Nickel oxide (NiO) thin films
For the synthesis of Nickel oxide as thin films, with the spray pyrolysis technical as a chemical method of deposit, on ordinary glass substrates heated to a fixed temperature of 500 °C. we use Nickel nitrate hexahydrate (99.5 %, Aldrich) as source precursor, dissolved in distilled water. Nickel oxide is a p-type semiconductor, is an important material because of its large direct optical gap between 3.6 and 4.0 eV; and easy to deposit in thin layers by many techniques, such as sol-gel and spray pyrolysis. Diagrams of X-ray diffraction (XRD), to confirm the formation of the phase have characterized the structure of the films deposited by the pyrolysis spray technique. Where they showed that NiO are nanoparticle films and have preferred orientations according to (111) and grain sizes in the range of 15 to 48 nm. The surface morphology, absorption domain, molecular vibrations were characterized by scanning electron microscopy (SEM), UV-Visible Spectroscopy and Raman spectroscopy. Voir les détails
Mots clés : NiO, Raman, UV-Visible Spectroscopy, XDR
The influence of scale yielding conditions in the determination of the fracture load using both analytical and numerical approaches for the study of the elasto-static anti-plane problem of a crack in a semi-infinite strip containing a non-homogeneous zone
The elasto-static anti-plane problem of a crack in a semi-infinite strip containing a non-homogeneous zone was studied using two approaches. The first one consist on an analytical approach based on the solution of a Singular Integral Equation (SIE formulation) using the Dugdale-Barenblatt cohesive model and the second approach is a numerical method based on a finite element analysis using a bilinear cohesive model (FEM-CZM approach). The results were expressed in term of fracture load. The length of the developing cohesive zone ahead of the crack tip was deduced at the crack initiation. This critical length size which was normalized with the crack size is taken as a characteristic length for defining the small/large scale yielding conditions of the particular studied case. For the small cohesive zone sizes (small scale yielding conditions), the computed values of the fracture load show a small difference between analytical and numerical approaches. In the other hand for the case of large cohesive zone sizes, the obtained values of the fracture load show significant discrepancy between the two approaches. Voir les détails
Mots clés : Crack, Singular Integral Equation, FEM, cohesive models, scalCrack, scale yielding conditions
Qualitative and Quantitative Assessment of γ and δ Phases in Duplex Stainless Steel Weldments by the X-Ray Diffraction Technique
This paper is focused on the quantitative and qualitative characterization of austenitic-ferritic stainless steel welds by the X-ray diffraction technique. The first weldment realized by gas tungsten arc welding process GTAW with ER2209 electrode, the second weldment by shielded metal arc welding process SMAW with E2209-15 electrode. The results show that the presence of two phases, austenite γ and ferrite δ without any precipitation of secondary phases either in the base metal BM or in the two welded zones. Moreover, there is an increase in the ferrite content and the existence of non-uniform compressive stress in the GTAW weld zone. Voir les détails
Mots clés : welding, X-ray diffraction technique, duplex stainless steel, ferrite and austenite
Simulation and Modeling of Uncertainties in the Calibration of a Fluorescence Chemical Spectrometer (FRX)
Sensitivity analysis and uncertainty estimation are of major importance for the declaration of conformity of finished products. Models must be sought to analyze the test data. The main objective of this work is to establish reliable models to analyze our experimental data and validate them. So we have studied and used the Monte Carlo and Bootstrap simulation methods, we have been able to realize programs that calculate the uncertainty according to the ISO 8466 standard on X-ray fluorescence spectrometer samples from the URASM CRTI chemical analysis laboratory. Programs and interfaces are made with Matlab (GUI). Voir les détails
Mots clés : Simulation; uncertainties; Monte carlo; Bootstrap; calibration