Liste des publications
New Approach to Modeling a planar flexible continuum robot simulating elephant trunk
Research on the modeling of continuum robots is focused on ways to construct the geometric models, while maintaining maximum specificities and mechanical properties of the robot. This paper presents a new approach of geometric modeling of continuum planar multi- sections robots, assuming that each section is curved in a circular arc, while having inextensible central axis of the structure. The direct geometric model is calculated analytically, whereas the extreme points (used in calculating the inverse geometric model) of each section are calculated numerically using a particle swarm optimization (PSO) method. One advantage of this method is to simplify the mathematical calculations and transform the complex problem into a simple numerical function; which allows the knowledge of the form of the central axis of the robot. Simulation examples using this method are carried to validate the proposed approach. Voir les détails
Mots clés : Flexible Continuum Robot, central axis, PSO, Khalil Klifinger method
Dynamic Response of a Stand Alone AC Side Wind Energy Conversion System
This Paper consists on the study of one part of wind energy system conversion, its ACside. Renewable resources are in constant fluctuation. This situation could put in peril the energizing efficiency towards a given demand requirement. Therefore, in order to maximize the efficiency of the renewable energy system, it is necessary to track the maximum powerpoint of the input source, a study established under MATLAB/Simulink platform. For the wind system, the maximizing is assured while considering the optimal power curve as load characteristic, with the knowledge of the turbine characteristic C_p (λ).Then, this work elaboratesthe analysis and simulation of a low speed Permanent Magnet Synchronous Generator (PMSG) driven by a vertical wind turbine through a Pulse-Width Modulation (PWM) voltage inverter, independently of the DC components of the wind system conversion, usingMATLAB computer simulation. Voir les détails
Mots clés : Wind, Optimal load characteristic, Compensation decoupling, IP regulator, Permanent Magnet Synchronous Generator.
Extraction and desextraction of a cationic dye using an emulsified liquid membrane in an aqueous solution
The removal of methylene blue (C16H18ClN3S) as a cationic dye which might be rejected in textile industry wastewaters during its production or its use was the main objective in this work. The extraction was performed by an emulsified liquid membrane (ELM) consisting of sorbitan mono-oleate (SPAN80) and di(2-ethylhexyl)phosphoric acid (D2EHPA) as a surfactant and an extractant respectively. The internal phase used was sulfuric acid. Effects of important factors (concentration of H2SO4, stirring velocity, quantities of organic, aqueous, phases, external and emulsified phases, concentrations of extractant and surfactant were studied according to the stability of the ELM. Then using favorable conditions for a good stability of the membrane, the extraction and of methylene blue (MB) from an aqueous solution was investigated. Optimal conditions were then determined and the extraction efficiency reached 98.15%. The desextraction of this dye was performed at 81.91% and the membrane was regenerated. Voir les détails
Mots clés : emulsified liquid membrane, emulsion W/O, extraction, methylene blue, desextraction
Effects of Niobium and Molybdenum on Microstructures after Hardening and Wear Resistance of Austenitic Manganese Steel
Hadfield steel has been wildly used to manufacture railway crossings because of its excellent work hardening, high strength and toughness properties. The hardness of Hadfield steel is only about 20 HRC when subjected to water toughening. This low hardness is usually associated with poor wear resistance and severe plastic deformation, as well as abrasion of the working surface of the railway crossing during the initial service period, which remarkably reduces its service lifetime. In this study we focus on the influence of niobium and molybdenum on the phenomenon of surface hardening or work hardening and wear resistance. The transformation of austenite during operation, thus determines the steel operating lifetime, the rate of transformation of austenite to martensite can introduce a compromise between ductility and wear resistance of the steel to support large efforts without breaking. The objective of this study is to improve the wear resistance by abrasion and friction after heat treatment of manganese steel alloyed with niobium and molybdenum. The addition of niobium and molybdenum promotes secondary hardening and allows slower transformation of austenite during the heat treatment. The results showed that the introduction of niobium and molybdenum has strongly influenced the character of the structure crystallization before hardening (Part hardened) by precipitation carbides form and finesse variables is observed in the microstructure before heat treatment and complete dissolution is noted after heat treatment, for the hardened part (work hardening) we observed a greater thickness and hardness compared to the base steel and net improvement in wear resistance. Voir les détails
Mots clés : Hadfield steel, Effects of Niobium and Molybdenum, Wear Resistance
Analog Circuit Implementation of FractionalOrder Damped Sine and Cosine Functions
This paper introduces for thefirst time analog circuitimplementations of two fundamental linear fractional order systems whose impulse responses called fractional order damped sineand cosine functions are the inverse Laplace transform of their irrational transfer functions. These analog circuit implementationsare derived through rational function approximations of their irrational transfer functions. Voir les détails
Mots clés : Analog circuit, fractionalorder differential equation, fractional order system, irrational function, rational function.
Effect of Substrates on the Properties of ZnO ThinFilms Grown by Pulsed Laser Deposition
Polycrystalline zinc oxide (ZnO) thin films have been deposited at 450˚C onto glass and silicon substrates by pulsedlaser deposition technique (PLD). The used source was a KrF excimer laser (248 nm, 25 ns, 5 Hz, 2 J/cm2). The effectsof glass and silicon substrates on structural and optical properties of ZnO films have been investigated. X-ray diffraction patterns showed that ZnO films are polycrystalline with a hexagonal wurtzite—type structure with a strong (103)orientation and have a good crystallinity on monocrystalline Si(100) substrate. The thickness and compositional depthprofile were studied by Rutherford Backscattering spectrometry (RBS). The average transmittance of ZnO films deposited on glass substrate in the visible range is 70%. Voir les détails
Mots clés : ZnO, Thin films, PLD, Silicon, X-ray diffraction, Optical transmittance, RBS
Characteristics of Al-doped TiO2 thin films grown bypulsed laser deposition
Al-doped TiO2 (TiO2:Al) thin films were deposited at 450ºC ontoglass substrates using pulsed laser deposition method. X-rays diffractionspectra showed that the obtained films are polycrystalline of anatase structurewith preferential orientation of (101) direction. AFM images, nanoparticles sizeand surface roughness mean square values showed that the surfaces of TiO2:Alfilms are smoother than that of undoped TiO2 films. A blue shift in theabsorption edge of TiO2 with increasing Al concentration in the film isnoteworthy as it leads to increase in the width of the optical transmission. Theoptical waveguiding performances of the TiO2:Al films were demonstrated byusing the m-lines spectroscopy technique and the results were correlated to thestructural properties. Spectroscopic ellipsometry was used to extract the opticalconstants of the films. The determined band gap of undoped and Al doped filmsvaries from 3.43 to 3.61 eV, which is in accordance to Burstein-Moss shift. Voir les détails
Mots clés : Al-doped TiO2, structure, morphology, optical properties, waveguide, nanoparticles
Extraction of weld defects dimension from radiographic images using the level set segmentation without re-initialization
Radiographic images segmentation is the major interest for the weld defect diagnosis and monitoring in the field of industry. In this work we present a method that takes ownership of local segmentation geodesic active contours. The goal of the method presented in this paper is to automate the process of extracting dimension of weld defects from radiographic images using level set segmentation. The information would be used in the area of nondestructive testing (NDT). This method is found to be effective and robust. Voir les détails
Mots clés : radiographic method, weld inspection, defect dimensions, Signal processing
Numerical investigations of ultra wide-band stacked rectangular DRA excited by rectangular patch
In this paper, a numerical study of a new ultra wideband (UWB) dielectric resonator antenna (DRA) is presented. The proposed structure consists of two stacked dielectric resonators excited by rectangular patch and operated from 3 GHz to 11 GHz (an impedance bandwidth of 115%), covering the full UWB spectrum. The analysis is carried out using the Finite Difference Time Domain (FDTD) method and two commercial electromagnetic simulators. The numerical results are given and compared in terms of reflection coefficients, radiation pattern and gain. The computed FDTD results are in good agreement with those of simulations. Voir les détails
Mots clés : numerical analysis, Finite Difference Time Domain (FDTD) method, stacked dielectric resonators
Experimental Investigations of Ultra-Wideband Antenna Integrated with Dielectric Resonator Antenna for Cognitive Radio Applications
In this paper, an ultra-wideband (UWB) patch antenna integrated with a dielectric resonator is proposed for cognitive radio applications. The patch antenna is fed by a coplanar waveguide (CPW) line, and it consists of a rectangular monopole having an elliptical base, and operates from 2.44 to 12 GHz. This UWB antenna is intended to collect the information. Moreover, the proposed structure integrates a narrow-band rectangular dielectric resonator antenna (RDRA) for operation, with very good isolation between the two ports (transmission coefficient S21 less than -20 dB). The RDRA provides a bandwidth from 5.23 GHz to 6.11 GHz. The electromagnetic analysis is carried out using tow commercial software tools. Furthermore, to validate the proposed concept, experimental measurements are also performed. Voir les détails
Mots clés : Integrated UWB/NB antenna, Cognitive radio applications