Electronique
Simulation en 2D du soudage par induction des tubes en Acier
Notre approche est essentiellement basée sur l’étudede modilisation et simulation de soudage par indection electromagnetique a haut frequence des pipes ligne il s’agit d’assembler deux tubes de diamètre quelconque.Nous avons décrivons les modèles mathématiques électromagnétiques et thermiques de notre configuration à souder que nous utilisons et étudier en détaille l’influence des différant paramètres sure la qualité de soudage Voir les détails
Mots clés : soudage par indection; pipes ligne; modèles électromagnétiques et thermiques
Interface and electrical properties of Au catalysts(dots) on Ge(111)
We investigate the interface between Au nanodots and a Ge(111) substrate. Au dots are achieved by dewetting an Au layer above the Au-Ge eutectic temperature TE(TE= 362°C). Surface and interface structural properties are analysed by using scanning tunnelling microscopy, transmission electron microscopy and scanning electron microscopy measurements while electrical characterizations are performed a by 4-points I-V probe Voir les détails
Mots clés : Au-Ge contacts, eutectic, Au droplets, germanium
Performance Analysis of Control techniques of Full-Bridge Resonant Inverter for Induction Metal Surface Hardening
In this paper, several control techniques for induction metal treating are examined to assess their performances using resonant series inverter. In fact, many types of steel are treated with heat to increase toughness and resistance to wear. Induction heating seems to be appropriate and provides several advantages in comparison with conventional techniques. In this paper, these techniques are evaluated comprehensively, through simulation and experiment, and compared to each other in terms of heating rate and efficiency, using one metal sample hardened to 1mm in depth up to 700°C, with a 400 W power supply. The simulation results obtained are satisfactory, and agree with those of the experiments. Furthermore, the study shows the control strategy based on frequency may not be sufficient, but should be associated with other control techniques in order to address appropriately the hardening pr ocess, bearing in mind processing time and efficiency. The strategy with frequency associated with phase shift control appears to fit well metal treating during the hardening, and can be easily tailored to its hardening requirements, compared to the other techniques Voir les détails
Mots clés : Induction metal hardning; Resonant Inverter; Power control
Digital Load Adaptive Control for Resonant Inverter for Surface Metal Heating
Induction heating is a well-known technique to produce very high temperature at reduced time for well specific applications such as in melting steel, brazing, and hardening.Series resonant converter proves to suit better to surface metals treatment and hardening. Efficiency reaches its highest level in the resonant mode, where switching losses are minimized by operating the IGBT at a resonant frequency for switching at the zero crossing point of current or voltage.However, as heat rises during hardening metal process, the metal exhibits parameter variations, which ultimately affects the overall system performances. Therefore, the inverter system with an effective load-adaptive control circuit with short response time is highly sought to let the system operate efficiently regardless of any variation of the load parameters. This will bring back the system under resonant mode to allow the system to operate at its optimal performances. In this paper, an analysis of a series resonant inverter performance is conducted, in which the control frequency is monitored and continuously adapted using phase-locked loopaimed to metal hardening. The control technique is characterized by its flexibility, low cost hardware, and shortresponse time. The system comprises analogue and digital circuits, microcontroller based. The experimental bench is built for the purpose in the range of 1 to 5 kW power, with 01to 50 kHz operating frequency. First, the process principle and the design procedure of the inverter system with the proposed control scheme are described through modelling and simulation. Then, experimental results are presented to show the validity of this technique, and to evaluate the system performances Voir les détails
Mots clés : Series resonant inverter, Load adaptive control
Étude de la propagation des ondes de Lamb dans une plaque fissure
La propagation des ondes de Lamb, dans un guide d’onde élastique, a été étudiée expérimentalement et numériquement. Ce guide d’onde est une plaque d’acier d’épaisseur e = 1.51 mm. Cette plaque comporte un défaut (une rainure de largeur de 3 mm et d’épaisseur de 0.5 mm) situé à 4 cm par rapport à l’extrémité libre de la plaque. La simulation a été faite en utilisant la méthode des éléments finis sous le logiciel Comsol Multiphysics. Les ondes de Lamb ont été expérimentalement générées par contact au moyen d’un transducteur piézoélectrique monté sur un sabot en plexiglas d’angle fixe. Quant à leur détection, un vibromètre laser a été utilisé. Dans cette étude, nous nous sommes intéressés à l’identification des modes de Lamb propagatifs dans la plaque inspectée. Pour cela, nous avons appliqué différentes méthodes de traitement du signal aux résultats obtenus numériquement : la représentation espace-temps, la transformée de Fourier spatiotemporelle ainsi que la Pseudo-Distribution de Wigner-Ville Lissée. Cette dernière a été également utilisée pour traiter les résultats expérimentaux. L’étude révèle un bon accord entre les résultats numériques et expérimentaux. Nous montrons que la Pseudo-Distribution de Wigner-Ville Lissée est très efficace en terme de détection du défaut existant dans la plaque ainsi quepour l’identification des modes de Lamb multiples résultant de l’interaction de l’onde incidente avec la rainure Voir les détails
Mots clés : Ondes de Lamb; simulation par éléments finis ; analyse temps-fréquence
Two-Port MIMO Cylindrical Dielectric ResonatorAntenna For LTE Systems
In this paper, a single cylindrical dielectric resonatorantenna (CDRA) is designed and proposed for multi-input multioutput(MIMO) wireless communications. The proposed antennais excited from two ports and operated around the samefrequency 1.9 GHz, suitable for the 33 and 35 LTE bands. Theproposed design exhibits high isolation between the two ports,with a transmission coefficient less than -35 dB. Theelectromagnetic analysis is carried out using CST microwavestudio and HFSS software. The numerical results, obtained fromsimulation, show a good agreement in terms of S-parameters andradiation patterns. Voir les détails
Mots clés : cylindrical dielectric resonatorantenna (CDRA), multi-input multioutput(MIMO)
3D-FDTD Analysis of Rectangular Printed Monopole Antenna for UWB Applications
This paper presents numerical study of ultrawideband(UWB) patch antenna using both the FiniteDifference Time Domain (FDTD) method and Ansoft HFSSSoftware. The patch antenna, which consists of a rectangularmonopole, is fed by microstrip line and operates from 3 to 10.9GHz, covering the UWB frequency band. The numericalresults, obtained from computed FDTD model and HFSSsimulation, are given and compared in terms of reflectioncoefficients and radiation patterns, and show good agreements. Voir les détails
Mots clés : Monopole antenna, FDTD method, UWB applications.
Rectangular Dielectric Resonator Antenna Array for 5.8GHZ WLAN Applications
In this paper, design of two rectangular dielectricresonator antenna (DRA) array is presented for wireless localarea networks (WLAN) applications (in the dual frequencyrange 5.15-5.35 GHz and 5.72-5.85 GHz).The DRA array isexcited by microstrip feed line through a single slot located inthe ground plane.The numerical analysis is carried out based on the finitedifferencetime-domain (FDTD) method. The numerical resultsin term of return losses and radiation patterns of the dielectricresonator (DR) antenna operating in TE111 mode are presentedand compared with those of a commercial electromagneticsoftware HFSS. A good agreement between the two simulatedresults was obtained. Voir les détails
Mots clés : Rectangular DRA array, wireless local area network (WLAN), FDTD method
Numerical Analysis of a Microstrip MIMO Antenna Array
In this paper, we present a simulation anddesign of a microstrip MIMO antenna array. The basic configuration is a microstrip patch antennas consist of ametallic patch on one side of the dielectric substrate with aground plane on the other side. The antenna system consists of2x4 radiating elements of similar geometry printed on asubstrate. The designed antenna is excited using the microstripfeeding .The theoretical analysis is based on the finitedifferencetime-domain (FDTD) method. In these analyses thecharacteristics of the MIMO antenna arrays are presented interms of return loss, mutual coupling, gain and radiationpatterns. The proposed antenna is simulated by using HighFrequency Structure Simulator (HFSS). The designed antennais suitable for MIMO systems operating for several WLANapplications. Voir les détails
Mots clés : Microstrip antenna, MIMO system, Resonant Frequency, Radiation Pattern, FDTD Method.
Ultra-Wideband Antenna Integrated with Dual-Band Dielectric Resonator
In this paper, we proposed a novel integrated ultrawideband(UWB) monopole antenna with dual-band antenna.The antenna consists of planar rectangular with semi-ellipticalbase and a rectangular dielectric resonator (DRA) with dualbandoperation. Both of them are excited via coplanar waveguide(CPW) lines. The numerical results show that the planarmonopole provides a -10dB impedance bandwidth between 2GHzand 12 GHz which largely covers the entire UWB spectrum, andthe rectangular DRA operates at two bands; 5.7-6.2 GHz and 8.2-9.7 GHz. The electromagnetic analysis is carried out using CSTmicrowave studio and HFSS software. The numerical results,obtained from simulation, are given and compared in terms of Sparameters and radiation patterns. Voir les détails
Mots clés : CPW-fed line, dielectric resonator antenna (DRA), Dual-band antenna, Integrated antennas, UWB antenna.