Liste des publications
Numerical and Experimental Investigation of FluidicMicrodrops Manipulation by Fluidic Mono-Stable Oscillator
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
Numerical Investigation of Flow Dynamic in Mini- Channel: Case of a Mini Diode Tesla
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.
A Lossless hybrid wavelet-fractal compression for welding radiographic images
In this work a lossless wavelet-fractal image coder is proposed. The process starts by compressing and decompressing the original image using wavelet transformation and fractal coding algorithm. The decompressed image is removed from the original one to obtain a residual image which is coded by using Huffman algorithm. Simulation results show that with the proposed scheme, we achieve an infinite peak signal to noise ratio (PSNR) with higher compression ratio compared to typical lossless method. Moreover, the use of wavelet transform speeds up the fractal compression algorithm by reducing the size of the domain pool. The compression results of several welding radiographic images using the proposed scheme are evaluated quantitatively and compared with the results of Huffman coding algo-rithm. Voir les détails
Mots clés : Fractal image compression, Wavelet-Fractal coder, lossless wavelet-fractal compression, Huffman algorithm, Radiographic images of weld defects
Stady and analysis of mechanical and viscoelastic behavior in flexure of laminated composites
In the present paper, seven laminated composites were thesubject of an experimental study to determine their mechanical and viscoelastic properties by means of dynamic mechanical analysis in a bending configuration. The influenceof the frequency, fiber type and fiber orientation on dynamic mechanical properties of different system composites were investigated. Carbon/epoxy laminates exhibit agreat stiffness when fibers are oriented along the axis ofthe clamps, and the maximum modulus was reported forunidirectional carbon/epoxy laminate [08 plies] with56.4 GPa. The glass transition temperature was found to decrease with the incorporation of fibers and increase with increased frequency. For the Kevlar/epoxy laminate, an increase of 12.5 8C in glass transition temperature wasobserved. This is related to a better interfacial adhesion between epoxy matrix and Kevlar fibers. Voir les détails
Mots clés : Composite laminate; Dynamic mechanical analysis; Fiber/matrice interface; Glass transition temperature
DIAGNOSIS OF THE AC CURRENT DENSITIES EFFECT ON THE CATHODIC PROTECTION PERFORMANCE OF THE STEEL X70 FOR A BURIED PIPELINE DUE TO ELECTROMAGNETIC INTERFERENCE CAUSED BY HVPTL
This paper diagnosis the effect of the AC current densities induced by the electromagnetic interference between high voltage power line and buried power line on the cathodic protection performance of the X70 steel in simulated soil. First, the induced AC voltage onto the pipeline was calculated for different power line configuration, separation distances between transmission line and pipeline and parallelism lengths. The induced AC current density was calculated function to the induced AC voltage, soil resistivity, and holiday diameter. Then, the electrochemical characters of the X70 steel at various AC current densities are measured using the potentiodynamic method. The electrochemical parameters obtained by the electrochemical tests are used as boundary conditions in the cathodic protection simulation model. The results indicate that, under influence of AC current densities, the X70 steel is more susceptible to corrosion, and the cathodic protection is unable to maintain the protection potential. Voir les détails
Mots clés : cathodic protection, electromagnetic interference, AC Corrosion
Software Features Extraction From Object-Oriented Source Code Using an Overlapping Clustering Approach
For many decades, numerous organizations have launched software reuse initiatives to improve their productivity. Software product lines (SPL) addressed this problem by organizing software development around a set of features that are shared by a set of products. In order to exploit existing software products for building a new SPL, features composing each of the used products must be specified in the first place. In this paper we analyze the effectiveness of overlapping clustering based technique to mine functional features from object-oriented (OO) source code of existing systems. The evaluation of the proposed approach using two different Java open-source applications, i.e. “Mobile media” and “Drawing Shapes”, has revealed encouraging results. Voir les détails
Mots clés : feature model, software product line, overlapping clustering, reverse engineering, program analysis
Numerical study of air preheating effect on NOx emissions in a heating furnace
This work aims to evaluate the reduce pollutant emission by steel reheating furnaces and operating process of the diffusion flame industrials burners. The example developed here is particularly interested in the influence of the air preheating temperature on NOx emissions as well as the dynamic characteristics and heat flow. The study was conducted on an industrial gas burners 250kilowatt. Numerical simulations are per formed using the computer code FLUENT, using the turbulence standard k-ε model coupled to turbulent combustion ED (Eddy Dissipation). The probability density function PDF model (6 species and reactions 3) with a chemical equilibrium model. The results obtained for different air preheat temperatures show that NOx emissions depend on the air preheat temperature. Voir les détails
Mots clés : pollutant emission, industrials burners, turbulent combustion
Poly Chlorure de Vinyle (PVC) Plastifié par des Mélanges des Plastifiants d’origineBiosourcés : Synthèse et Caractérisation
L’huile de tournesol époxydée (HTE) avec un indice d’oxyrane de 4,5 a été synthétisée à partir de l’huile de tournesol vierge et l’eau oxygénée (H2O2) en présence de l’acide formique. L’HTE est utilisée avec le di esters isosorbide (DEI) comme un système plastifiant biosourcé dans le PVC en combinaison avec un plastifiant classique soit le di-éthyle-2-hexyle phthalates (DEHP).Après fabrication des films (0,5 mm d’épaisseurs) de différents pourcentages des plastifiants dans un mélangeur à deux cylindres, on a réalisé les essais de la migration et d’excudation des plastifiants des formulations obtenues. La migration des plastifiants biosourcés (DEI ou HTE) en combinaison avec le DEHP est suivie par les tests de volatilité, d’extraction et de lessivage. Les pertes des masses des formulations plastifiées réalisées obtenues par les différents modes de caractérisation à savoir: la volatilité, l’extraction dans l’eau distillée et dans la gazoline et le lessivage dépendent de la pression devapeur, de la masse moléculaire, de la solubilité, de la compatibilité et de la structure chimique du plastifiant. Voir les détails
Mots clés : PVC, Biosourcé, Epoxydation, plastifiants
Study of Composite with Metallic Matrix WC/W2C–20W–20Ni Realized by Spontaneous Infiltration ofthe Bronze Alloy Cu–30Mn–3P
The improved performance and duration of an impregnated tool for the mineral drilling requires thoroughunderstanding of the mechanisms involved in the consolidation of powder mixtures in the liquid phasesintering cycle (FPL). The elements used for the manufacture of the active parts of these tools are usuallymade from mixtures of loose powders based on WC/W–Ni. The spontaneous infiltration process is themost appropriate method offers a big possibility of shapes due to molding. It lets to have considerabledensity of the metal matrix composite (MMC) constituting the active head and increase its resistance toerosion and abrasion. This work consists to develop a metal matrix composite which can constitute theactive part of a drilling tool impregnated by the infiltration of industrial process SILP (Sintering byInfiltration of an appropriate mixture of Loose Powders). The mixture of loose powders (WC/W2C–W–Ni)is infiltrated under hydrogen by a manganese bronze (Cu–30Mn–3P) and then characterized by DTA,optical microscopy, SEM coupled with EDS, HRA hardness and micro-hardness Hv0.1. Voir les détails
Mots clés : Applied Mechanics, Behavior of Materials, Engineering Systems
Low-profile U-shaped DRA for ultra-wideband applications
In this paper, a microstrip-fed U-shaped dielectric resonator antenna (DRA) is simulated, designed, and fabricated. This antenna, in its simple configuration, operates from 5.45 to 10.8 GHz. To enhance its impedance bandwidth, the ground plane is first modified, which leads to an extended bandwidth from 4 to 10.8 GHz. Then by inserting a rectangular metallic patch inside the U-shaped DRA, the bandwidth is increased more to achieve an operating band from 2.65 to 10.9 GHz. To validate these results, an experimental antenna prototype is fabricated and measured. The obtained measurement results show that the proposed antenna can provide an ultra-wide bandwidth and a symmetric bidirectional radiation patterns. With these features, the proposed antenna is suitable for ultra-wideband applications. Voir les détails
Mots clés : Ultra-wideband applications, Dielectric resonator antenna, Low-profile antenna, Measurements