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Nombre total de résultats : 1832
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Design of Sobel Filter in VHDL

Mazouz Nezhate, Bouhouche Salah, Ziad Mostepha, DRAI Redouane  (2018)
Article de conférence

In order to automate the quality control process of pipe’s welding joint, we present in this paper a new design of an embedded computer vision system, which is based on a camera, controlled by an FPGA platform (Zynq-7000) for acquisition and image processing on the same FPGA circuit. A VHDL implementation of Sobel Edge Detection Algorithm is proposed. The obtained results were validated with those obtained by MATLAB.This will allow us to develop other tools more powerful and more robust. Voir les détails

Mots clés : Quality control, pipe welds, FPGA, Sobel, VHDL

Analyse par spectroscopie Infrarouge à transformée de Fourier et diffraction des rayons X d’un matériau composite.

N. Sassane, L. Alimi, T. Guettaf Temam, M. HASSANI, S.Boukhezar  (2019)
Article de conférence

Les composites à matrice polymère sont utilisés en général comme des biomatériaux à cause de leurs constituants. Le matériau analysé est un composite à matrice en polymère renforcé par une fibre de verre utilisé comme prothèse orthopédique d’un tibia. Les résultats obtenus de diffraction des rayons X et spectroscopie Infrarouge à transformée de Fourier(FTIR) montrent la présence de la silice SiO2 et de l’alumine Al2O3 se sont parmi les constituants de la fibre de verre ainsi que la présence des molécules organiques se sont parmi les constituants de la résine polyester. Voir les détails

Mots clés : composite, Prothèse orthopédiques, DRX, FTIR.

Effet de la cinétique de précipitation sur la résistance à la corrosion de l’acier inoxydable duplex 2205 et de l’alliage d’aluminium 2000

DJAMA Mustapha (2018)
Thèse de doctorat

This thesis is subdivided into two main parts. First, the influence of the microstructure of the AA2214-T6 aluminum alloy on the morphologies and electrochemical properties of anodic alumina oxide films was investigated. (AAO) formed,  and then to see if the heat treatment T4 brought to the AA2214 alloy brought improvements in term of the morphologies of (AAO) and in term of resistance to the corrosion of the anodic alumina oxide films .Secondly, we orientate this work to correlate the pitting potential (Epit) evolution with the kinetics of σ phase precipitation in the 2205 duplex stainless steel aged at 850°C after solution treatment at 1150°C. The potentiodynamic polarization curves indicate a reduction of the pitting corrosion resistance with the aging time, which is revealed by a decrease in the Epit values from 0.65 to 0.40 VSCE. Thus, Epit values are used to determine the kinetics parameters of the σ phase precipitation. The experimental transformed fraction agrees well with the one calculated by using the modified Kolmogorov–Johnson–Mehl–Avrami equation with an impingement parameter c = 0.6. Voir les détails

Mots clés : Kinetics, KJMA, Pitting corrosion, Potentiodynamic polarization, sigma phase precipitation, Aluminum alloy, (AAO) anodic alumina oxide, porous structure, T4, EIS

Electric Field Distribution in point-insulating barrier-Plane System using experimental and Theoretical method

S.Benharat, S.Bouazabia, S.BELGACEM  (2019)
Article de conférence

The present paper deals with the influence of insulating barriers on the breakdown and the electric field distribution in the Point –insulating barrier- plane air gap system. An experimental investigation on the influence of different parameters such as gap distance between electrodes and barrier dimensions, under AC voltage, have been studied. The results show that the width and thickness of the insulating barrier effect the electric field variation which increases with increasing applied voltage. The experimental results are compared with a numerical model. Voir les détails

Mots clés : Electric field, Finite Element Method, breakdown voltage, insulating barrier, point- plane system

Microdrops in Microfluidic: Estimation of Geometrical Form

T. CHEKIFI, B. dennai, R. Khelfaoui  (2015)
Publication

Manipulation of small-sized liquid quantities is one of the key issues in technology, biology, chemistry and medicine.Where the increased surface-to-volume ratio making surface effects more dominant [42], which allows toreduce time of reaction and economies the costs of manufacturing products. The microdrop is a typical example of asmall-sized liquid quantity; that can be considered as samples, reagents and supplementary indicator to approach us inthe direction of reaction and the state of microdrop. The creation of reproducible in stable geometrical form ofmicrodrop makes a critical step during the manufacturing of microdrop. Pressure based manufacturing of microdropnowadays a common way to create reproducible and stable small-sized drops. Many geometrical form of microdropcan be generated in different techniques. Proofed that microdevices based on pressure based manufacturing ofmicrodrops has already been successfully implemented. This paper serves as a review of the most importantcontributions, in the development of the creation of reproducible and stable microdrops in the past decades. Besidesserving as a reverence for researchers in this area, this paper is also a resource for everybody who wants to identify theeasiest way to precise microdrops geometrical form for a particular application by simple analysis. Voir les détails

Mots clés : form, microdrop, description and theoretical analysis.

Numerical Simulation of Droplet Breakup, Splitting andSorting in a Microfluidic Device

T. CHEKIFI, B. dennai, R. Khelfaoui  (2015)
Publication

Droplet generation, splitting and sorting are investigated numericallyin the framework of a VOF technique for interface tracking and a finite-volumenumerical method using the commercial code FLUENT. Droplets of water-in-oilare produced by a flow focusing technique relying on the use of a microchannellequipped with an obstacle to split the droplets. The influence of several parameterspotentially affecting this process is investigated parametrically towards the endof identifying "optimal" conditions for droplet breakup. Such parameters includesurface tension, the capillary number and the main channel width. We show thatthe capillary number plays a crucial role in determining droplet properties and theefficiency of the related generation process. An obstacle configuration can be effectivelyused to split a droplet, with the droplets being naturally sorted at the endof the main channel. Larger values of the capillary number generally lead to anincrease in the droplet frequency and a decrease in its typical size. Voir les détails

Mots clés : Water droplet, flow focusing, splitting, sorting, CFD, VOF, microchannel

Numerical Investigation of Flow Dynamic in Mini- Channel: Case of a Mini Diode Tesla

B. dennai, M. belboukhari, T. CHEKIFI, R. Khelfaoui  (2016)
Publication

Microfluidic systems are used and exploited in various fields, as they are highly specific and developed in their use. The micro devices are used in various analyzes of medical disciplines, chemical and other fields. Our research team "MAAt" within ENERGARID laboratory is in the process of triggered several lines of research in this area, the micro-mixing, separation of micro particles, droplet production. For that, we need tools and micro devices to study the phenomena.. In this work, we present a theoretical study and numerical simulation of micro device (micro diode Tesla). A Diode Tesla is similar to a heart valve conduit profile is shown in the following figure: In this simulation work, we will focuse the variation of geometrical parameters, the inside length lw (lw1> lw2> lw3), this study aims to optimize this setting to get a better efficiency. Then we will investigate the effect of the pressure variation on the volume flow. Voir les détails

Mots clés : Mini channel, diode Tesla, Efficiency, gas flow, microsystem.

Numerical and Experimental Investigation of FluidicMicrodrops Manipulation by Fluidic Mono-Stable Oscillator

T. CHEKIFI, B. dennai, R. Khelfaoui, A. Maazouzi  (2016)
Publication

A numerical and experimental study of passive microdrops manipulation hasbeen presented. This paper focuses on the modeling of micro-oscillators systemswhich are composed by passive amplifier without moving part. The characteristicsize of the channels is generally about 35 ¹mof depth. The numerical results indicatethat the production and manipulation of microdrops are possible with passivedevice within a typical oscillators chamber of 2:25 mm diameter and 0:20 mmlength when the Reynolds number is Re = 490. The novel microdrops methodthat is presented in this study provides a simple solution about the production ofmicrodrops problems in micro system. We undertake an experimental step. Thefirst part is based on realization of sample oscillator; the second part is consistedof visualization of the microdrops production and its manipulation. Voir les détails

Mots clés : microdrop, fluidic oscillator, CFD

MicroFluidic Oscillator: A Technical Solutionfor MicroMixture

B. dennai, A. BENTALEB, T. CHEKIFI, R. Khelfaoui, A. Abenbi  (2015)
Publication

The diffusion flux given by the Fick’s law characterizethe mixing rate. A passive mixingstrategy is proposed to enhance mixing of two fluids through perturbed jet low. A numerical studyof passive mixers has been presented. This paper is focused on the modeling of a micro-injectionsystems composed of passive amplifier without mechanical part. The micro-system modeling isbased on geometrical oscillators form. An asymmetric micro-oscillator design based on amonostable fluidic amplifier is proposed [2,7]. The characteristic size of the channels is generallyabout a few hundred of microns. The numerical results indicate that the mixing performance can beas high as 99 % within a typical mixing chamber of0.20 mm diameter inlet and 2.0 mm distance ofnozzle - spliter. In addition, the results confirm that self-rotation in the circular mixer significantlyenhances the mixing performance. The novel micro mixing method presented in this study providesa simple solution to mixing problems in microsystem. Voir les détails

Mots clés : Micro oscillator, modeling, Micro mixture, diffusion, Size effect.

Effect of Geometrical Parameters on Vortex Fluidic Oscillators Operating with Gases and Liquids

T. CHEKIFI, B. dennai, R. Khelfaoui  (2018)
Publication

The fluidic oscillator is an interesting device developed for passive flow measurement. These microsystems can produce a high oscillating jet frequency with high flow velocity. The main advantages of fluidic oscillators are that no moving parts is included in the device. Commercial CFD code FLUENT was used to perform analysis of flows in fluidic oscillator. Numerical simulations were carried out for different flow conditions, where water and air were used as working fluids. The oscillation frequencies were identified by the discrete fast Fourier transform method (FFT). Furthermore a low-pressure vortex of fluid flow in the oscillating chamber was observed. The effect of the operating pressure and the oscillating chamber shape on the fluidic oscillator performance is investigated. Moreover the velocity fluctuations of the feedback flows through both feedback channels and the output were determined quantitatively. In addition, the behaviour of the low-pressure vortex in both models is analysed. Also, numerical result revealed small vortices are developed at the end of nozzle while oscillation, which maintains the deflection of jet flow between attachments wall. Comparison of our numerical simulations with available results showed reasonably and good agreement. Voir les détails

Mots clés : fluidic oscillator, CFD, oscillating chamber, vortex, size effect, Coanda effect.