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116 results on '"Charrada, K"'

6. Optimization of the thermal distribution of multi-chip LED package

Author

Maussion, Pascal, Ben Abdelmlek, K., Araoud, Z., Charrada, K., Zissis, Georges, COmmande et DIAgnostic des Systèmes Electriques (LAPLACE-CODIASE), LAboratoire PLasma et Conversion d'Energie (LAPLACE), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Unité d’Éude des Milieux Ionisés et Réactifs [Monastir] (EMIR), Institut Préparatoire aux Etudes d'Ingénieurs de Monastir (IPEIM), Université de Monastir - University of Monastir (UM)-Université de Monastir - University of Monastir (UM), and Lumière et Matière (LAPLACE-LM)

Subjects
Materials science, business.industry, 020209 energy, Thermal resistance, Energy Engineering and Power Technology, 02 engineering and technology, 021001 nanoscience & nanotechnology, Chip, 7. Clean energy, Industrial and Manufacturing Engineering, Thermal management of high-power LEDs, [SPI.TRON]Engineering Sciences [physics]/Electronics, law.invention, LED lamp, Interference (communication), law, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, 0202 electrical engineering, electronic engineering, information engineering, Optoelectronics, Junction temperature, 0210 nano-technology, business, Thermal analysis, ComputingMilieux_MISCELLANEOUS, Light-emitting diode
Abstract

Light emitting diodes (LEDs) are fascinating a thermal problem due to the increase of their junction temperature. Thermal management of LED module is the key to improve the performances of LED. In this paper, a three dimensional thermal analysis of 3.5 W multi-chip COB (chip-on-board) LED package was developed using COMSOL Multiphysics®. An optimization of the number of LED-chip and their disposition on different substrate was carried out. The results showed that the interference of heat spreading in substrate level, the junction temperature and the thermal resistance of the LED lamp decreased well with the increase of gaps between chips and reached an optimal value. A correlation of optimal pitch was determined as a function of chip number, chip size and substrate size. It was found that using the optimal multi-chip model instead of one LED-chip leads to a decrease of the junction temperature about 12.54%, 14.96% and 17.1% for AlN, Al2O3 and IMS substrates respectively.

Published
2017
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7. Modelling and experimental investigations of DC electric arcs in argon and carbon dioxide

Author

Mohsni, C., Baeva, M., Franke, S., Gortschakow, S., Gonzalez, D., Araoud, Z., and Charrada, K.

Subjects
Plasma-electrode interaction, Electric arcs, Thermal plasma, Konferenzschrift, Plasma diagnostics
Abstract

In this work an arc model is employed along with electric and spectroscopic measurements to study DC electric arcs in Ar and CO2. The model is aimed at describing the arc and the electrodes. Simulation and experimental results are shown for currents between 150 A and 210 A.

Published
2019
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11. Place du prelevement ganglionnaire dans le traitement des cancers differencies de la thyroide n0 clinique

Author

Lachkhem, A, Khamassi, K, Foudhaili, H, Charrada, K, Touati, S, and El May, A

Abstract

Objectif : Mots-clés : Cancer différencié, thyroïde, prélèvement ganglionnaireDémontrer l’intérêt du prélèvement ganglionnaire sus-claviculaire et jugulaire inférieur dans la prise en charge des cancers différentiés de la thyroïde (CDT) N0 clinique. Matériel et méthodes : Nous rapportons une étude rétrospective à propos de 170 patients colligés sur 12 ans (1994-2005). Tous les patients ont eu une thyroïdectomie totale en 1 ou 2 temps. Le curage médiastino-récurrentiel a été pratiqué soit systématiquement soit en cas de découverte d’adénopathies en peropératoire. Le curage latéral a été réalisé soit de principe soit après un prélèvement ganglionnaire sus-claviculaire et jugulaire inférieur positif à l’examen extemporané. Des doses ablatives d’iode radioactif ont été administrées en cas d’élévation du taux de la thyroglobuline ou d’une fixation d’iode lors du balayage cervico-thoracique. Résultats : L’examen anatomopathologique trouvait un carcinome papillaire (74,1%), vésiculaire (16,5%) ou papillaire à composante vésiculaire (9,4%). Trente patients ont eu un curage fonctionnel systématique uni ou bilatéral, une métastase ganglionnaire a été notée chez 9 d’entre eux. Cent quarante patients ont eu un prélèvement ganglionnaire uni ou bilatéral, un curage fonctionnel a été pratiqué chez 6 d’entre eux devant un examen extemporané positif. Les taux de rémission, de récidive et de métastases étaient respectivement de 83,3%, 6,7% et 10% dans le premier groupe, et de 89,3%, 4,3% et 6,4% dans le deuxième groupe. Par ailleurs, un décés a été observé chez deux patients du deuxième groupe (1,4%) . Aucune différence statistiquement significative n’a été retrouvée entre les différents taux. Conclusion : Les résultats de notre série mettent en évidence l’intérêt du prélèvement sus-claviculaire et jugulaire inférieur permettant d’éviter le curage fonctionnel systématique.

Published
2010

17. A study of the convective flow as a function of external parameters in a high-pressure metal halide discharge lamp (HgDyI3).

Author

Hajji, S., HadjSalah, S., Benhalima, A., Charrada, K., and Zissis, G.

Subjects
CONVECTIVE flow, METAL halides, ELECTRIC discharges, ELECTRIC currents, PLASMA gases
Abstract

This paper deals with the modelling of the convection processes in metal-halide lamp discharges (HgDyI3). For this, we realized a 3D model, a steady, direct current powered and time-depending model for the solution of conservation equations relative to mass, momentum, and energy. After validation, this model was applied to the study of the effect of some parameters that have appeared on major transport phenomena of mass and energy in studying the lamp. Indeed, the electric current, the atomic ratio (Hg/Dy), and the effect of the convective transport have been studied. [ABSTRACT FROM AUTHOR]

Published
2016
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25. Fibromatose desmoïde à localisation nasale

Author

Kharrat, S, primary, Sahtout, S, additional, Charrada, K, additional, Riahi, K, additional, Tababi, S, additional, Zainine, R, additional, Nouira, K, additional, Beltaief, N, additional, Menif, E, additional, and Besbes, G, additional

Published
2010
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30. Calculation of a plasma HgDyI3 transport coefficients.

Author

Hajji, S., HadjSalah, S., Benhalima, A., Charrada, K., and Zissis, G.

Subjects
PLASMA physics, MERCURY compounds, PLASMA transport processes, COEFFICIENTS (Statistics), NUMERICAL calculations, THERMODYNAMIC equilibrium
Abstract

This work is devoted to the calculation of the chemical composition and transport coefficients of HgDyI3 plasmas in thermal equilibrium. These calculations are performed for pressures equal to 2MP and for temperatures varying from 1000 to 10 000 K. The thermal and electrical conductivity as well as viscosity have been computed as a function of temperature at different atomic ratios. The computational method proposed by Devoto from the classical formalism described by Hirschfelder et al. [Molecular Theory of Gases and Liquids (John Wiley and Sons, New York, 1954)] is used. [ABSTRACT FROM AUTHOR]

Published
2015
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31. Natural Convection Heat Transfer in an Enclosure Filled with an Ethylene Glycol—Copper Nanofluid Under Magnetic Fields.

Author

Ben Hamida, M.B. and Charrada, K.

Subjects
*NATURAL heat convection, *HEAT transfer, *ETHYLENE, *GLYCOLS, *NANOFLUIDS, *MAGNETIC fields
Abstract

This article presents the results of a numerical study on natural convection in a square enclosure filled with ethylene glycol–copper nanofluid in the presence of magnetic fields. Two opposite horizontal walls of the enclosure are insulated and the two vertical walls are kept constant at different temperatures. A uniform horizontal magnetic field is externally imposed. The governing equations (mass, momentum, and energy) are formulated and solved numerically with a finite element using COMSOL Multiphysics. The effects of pertinent parameters such as Rayleigh number (103 ≤ Ra ≤ 107), Hartmann number (0 ≤ Ha ≤ 120), and solid volume fraction (0 ≤ φ ≤ 0.06) on the flow and the heat transfer performance of the enclosure are examined when the Prandtl number is assumed to bePr = 151. [ABSTRACT FROM AUTHOR]

Published
2015
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32. Optimization methods of the net emission computation applied to cylindrical sodium vapor plasma.

Author

Salah, S. Hadj, Hajji, S., Hamida, M. B. Ben, and Charrada, K.

Subjects
SODIUM vapor, MATHEMATICAL optimization, PLASMA physics, LORENTZIAN function, RADIATIVE transfer
Abstract

An optimization method based on a physical analysis of the temperature profile and different terms in the radiative transfer equation is developed to reduce the time computation of the net emission. This method has been applied for the cylindrical discharge in sodium vapor. Numerical results show a relative error of spectral flux density values lower than 5% with an exact solution, whereas the computation time is about 10 orders of magnitude less. This method is followed by a spectral method based on the rearrangement of the lines profile. Results are shown for Lorentzian profile and they demonstrated a relative error lower than 10% with the reference method and gain in computation time about 20 orders of magnitude. [ABSTRACT FROM AUTHOR]

Published
2015
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