Thermodynamic properties calculation of air – water vapor mixtures thermal plasmas

Knowledge of air-water vapor mixtures thermal plasmas thermodynamic properties is important to estimate theperformances of electrical arc cutting in this gas by a circuit breaker. In this paper, air-water vapor mixtures thermalplasmas thermodynamic properties are calculated in a temperature range from 5000K to 30000K. The calculations arecarried out by supposing local thermodynamic equilibrium at pressure of 1; 5 and 10 atm. The obtained results showthe influence of the water vapor initial proportion but also that of the pressure on these plasmas thermodynamicproperties.Keywords: Mixture; plasma composition; thermal plasma; thermodynamic properties; circuit breakers

OFDM codée pour le haut débit en fibre optique avec les codes correcteurs convolutifs, BCH, RS et LDPC

Ce document présente une comparaison des performances des modulations OFDM (Orthogonal Frequency Division Multiplexing) codées pour la transmission optique haut débit à l’aide des techniques de codage canal convolutif, BCH, LDPC et Reed Solomon. L’évaluation des performances se base d’une part sur l’EVM (Error Vector Magnitude) afin d’apprécier les effets des imperfections du canal optique; et d’autre part sur l’estimation du taux d’erreur binaire (BER) en fonction de l’OSNR. Les simulations sont réalisées au débit de 10Gbit/s sur 1000 Km dans un environnement de cosimulation avec les logiciels VPITransmissionMaker et Matlab. Les résultats ont révélé que ces codes correcteurs d’erreurs et en particulier les codes LDPC sont bien efficaces et adaptées au haut débit, ils constituent des solutions satisfaisantes pour le COFDM dans la réduction des effets de la dispersion chromatique, de la PMD, des interférences entre symboles (ISI) et des non linéarités.Mots-clés : OFDM, haut débit, BER, fibre optique, codes correcteurs d’erreur.Coded OFDM for high-speed transmission in optical fiber with convolutional, BCH, RS and LDPC codes This paper presents a comparison of the performances of coded OFDM (Orthogonal Frequency Division Multiplexing) for optical broadband transmission using convolutional, BCH, Reed Solomon and LDPC channel coding techniques. The performance evaluation is based firstly on the EVM (Error Vector Magnitude) to assess the effects of imperfections in the channel, and secondly on the estimated bit error rate (BER) based on OSNR. The simulations are performed at a rate of 10Gb/s over 1000 km in a cosimulation environment using VPITransmissionMaker and Matlab software. The results showed that the error correcting codes and particularly LDPC codes are well suited and efficient for broadband, they provide satisfactory solutions for COFDM in reducing the effects of chromatic dispersion, PMD, Inter-symbol interference (ISI) and nonlinearities.Keywords : OFDM, broadband, BER, optical fiber, error correcting codes

Determination of equilibrium composition of C

In this paper, we determine the composition of CxHyOzNt plasmas out of thermodynamic equilibrium using a more rigorous thermodynamic derivation of the Saha equation modified to two-temperature plasma system proposed by Chen et al. The calculation is made for these plasmas in pressure range 0.1-1 MPa and for electron temperature range 5 000-30 000 K. A great attention is given to the evolution of the major species such as hydrogen components (H, H2), carbon monoxide (CO) and electrons. We compared the results obtained with our previous experimental and theoretical studies; the latter one has been carried out in equilibrium situation. We also compared our results with those given by the method based on the minimization of the Gibbs free energy widely used in the literature

Propriétés thermodynamiques et de transport des plasmas issus de la vaporisation des isolants PTFE et PE

At atmospheric pressure, the values of density, enthalpy, specific heat, sonic velocity, viscosity, thermal and electrical conductivities have been calculated for plasmas of PE and PTFE in the temperature interval 5 000 K-30 000 K. In hypothesis of LTE, equilibrium composition is calculated using the classical equations of thermodynamic, and transport coefficients are calculated using the Chapman-Enskog method. The accuracy of results is discussed in connection with the selection of the collision integrals of the different species

Thermodynamic properties calculation of Calpha Hbeta Ogamma Ntheta insulator plasmas

In the temperature range 5000-30000 K, thermodynamic properties of plasmas from vaporization of Calpha Hbeta Ogamma Ntheta insulators have been calculated in the pressure range from 1*105 Pa to 10*105 Pa. The method of calculation is indicated. The analysis shows that the respective proportions of carbon, hydrogen, oxygen and nitrogen atoms ( alpha , beta , gamma and theta ) in the organic molecule can notably modify the characteristics of the medium (plasma)

Composition et coefficients de transport des plasmas de matériaux plastiques (polymères)

Composition at equilibrium, electrical and thermal conductivities, and dynamic viscosity coefficient are calculated for plasmas produced by vaporization of plastic materials (polymers) containing some percentage of carbon, hydrogen, oxygen and nitrogen. Temperature and pressure ranges are 5000-30000 K and 0.1-1 MPa. By indicating the role played by somme particles on the characteristics of the discharge, this study has shown the influence of the nature of the material

BER Reduction for mQAM High-Speed Tranmission in Optical Fiber Networks Using Convalutional BCH, RS and LDPC Error Correcting Codes

A comparative study of digital m-ary Quadrature Amplitude Modulation (mQAM) channel coding signals for optical high-speed transmission is presented in this article. The needs to transmit information at high speed are topical and relevant to the images, the sounds, and data of any kind, etc. The photonic networks are the subject of much research on the application in optical domain of techniques already used in wireless networks such as mQAM digital modulations and error correcting codes. The mQAM digital modulations interest lies in the fact that they are now being used as subchannel modulation techniques in other advanced modulations such as Othogonal Frenquency Division Multiplexing (OFDM). Indeed, OFDM using mQAM modulation seems to be a good candidate in high speed networks. This allows considering transmission systems at very high speeds in optical transmission networks. The performance of channel coding is based on the estimation of the Bit Error Rate (BER) implementing techniques of Convolutional codes, Bose Chaudhuri Hocquenghem (BCH) codes, Reed-Solomon (RS) codes and Low Density Parity Check (LDPC) codes in a 10Gbps transmission. The BER is estimated as a function of the OSNR and also as a function of the transmission distance.The study was conducted in a software cosimulation environment with VPITransmissionMaker and Matlab software. The simulation results showed that error correcting codes and particularly LDPC codes are effective and provide satisfactory solutions to reduce the BER by fighting against optical transmission channel disturbances such as chromatic dispersion and nonlinearities.Keywords: mQAM, broadband, BER, optical fiber, error correcting codes

Influence des aérosols sur la composition à l'équilibre d'un plasma d'air

International audienc

Modélisation et simulation d’un champ photovoltaïque utilisant un convertisseur élévateur de tension (boost) avec le logiciel MATLAB /SIMULINK

International audienceCe travail présente une contribution pour une meilleure conception d’un convertisseur boost permettant à l’aide d’une commande de recherche du point de puissance maximale MPPT (Maximum Power Point Tracking) de retrouver la puissance maximale du champ photovoltaïque (PV) à tout moment.En effet à partir des modèles de convertisseur boost existant dans la littérature nous avons développé une variante de convertisseur et calculé ses différents paramètres. Les simulations réalisées avec Matlab/Simulink ont permis d’optimiser la production du champ PV et d’élucider le fait que le champ PV peut fonctionner à son point maximal de puissance s’il est interfacé par un convertisseur qui recherche à tout instant la puissance maximale