Documents disponibles écrits par cet auteur

An investigation of the effect of structural order on magnetostriction and magnetic behavior of Fe–Ga alloy thin films / A. Javed in Acta materialia, Vol. 58 N° 11 (Juin 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 11 (Juin 2010) . - pp. 4003–4011 Titre : An investigation of the effect of structural order on magnetostriction and magnetic behavior of Fe–Ga alloy thin films Type de document : texte imprimé Auteurs : A. Javed, Auteur ; T. Szumiata, Auteur ; N.A. Morley, Auteur Année de publication : 2011 Article en page(s) : pp. 4003–4011 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Fe–Ga  alloy  Thin  films  Growth  parameters  CEMS  Magnetostriction Résumé : This paper reports results from a comprehensive study of Fe–Ga films fabricated over a wide range of growth conditions. Polycrystalline Fe100−xGax films (14 ⩽ x ⩽ 32) were deposited (using three different combinations of growth parameters) on Si(1 0 0) using a co-sputtering and evaporation technique. The growth parameters (sputter power, Ga evaporation rate and chamber pressure) were used primarily to control the Fe:Ga ratio in the films. X-ray diffraction showed that all films had 〈1 1 0〉 crystallographic texture normal to the film plane. The lattice parameter increased with % Ga up to x = 22 and was independent of growth parameters. Conversion electron Mössbauer spectroscopy studies showed a predominance of the disordered A2 phase in all films. It appears that the use of vacuum deposition with appropriate parameters can effectively suppress the D03 ordered phase. Systematic studies of the effective magnetostriction constant as a function of composition support this conclusion. It was found that films of high effective saturation magnetostriction constant and low stress could be fabricated using low Ar pressure, irrespective of sputter power or evaporation rate, giving properties useful for application in microelectromechanical systems. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001680 [article] An investigation of the effect of structural order on magnetostriction and magnetic behavior of Fe–Ga alloy thin films [texte imprimé] / A. Javed, Auteur ; T. Szumiata, Auteur ; N.A. Morley, Auteur . - 2011 . - pp. 4003–4011. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 11 (Juin 2010) . - pp. 4003–4011 Mots-clés : Fe–Ga  alloy  Thin  films  Growth  parameters  CEMS  Magnetostriction Résumé : This paper reports results from a comprehensive study of Fe–Ga films fabricated over a wide range of growth conditions. Polycrystalline Fe100−xGax films (14 ⩽ x ⩽ 32) were deposited (using three different combinations of growth parameters) on Si(1 0 0) using a co-sputtering and evaporation technique. The growth parameters (sputter power, Ga evaporation rate and chamber pressure) were used primarily to control the Fe:Ga ratio in the films. X-ray diffraction showed that all films had 〈1 1 0〉 crystallographic texture normal to the film plane. The lattice parameter increased with % Ga up to x = 22 and was independent of growth parameters. Conversion electron Mössbauer spectroscopy studies showed a predominance of the disordered A2 phase in all films. It appears that the use of vacuum deposition with appropriate parameters can effectively suppress the D03 ordered phase. Systematic studies of the effective magnetostriction constant as a function of composition support this conclusion. It was found that films of high effective saturation magnetostriction constant and low stress could be fabricated using low Ar pressure, irrespective of sputter power or evaporation rate, giving properties useful for application in microelectromechanical systems. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001680

Effects of manufacturing noise on microturbine centrifugal impeller performance / A. Javed in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 10 (Octobre 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 10 (Octobre 2012) . - 09 p. Titre : Effects of manufacturing noise on microturbine centrifugal impeller performance Type de document : texte imprimé Auteurs : A. Javed, Auteur ; R. Pecnik, Auteur ; M. Olivero, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : gas turbines Langues : Anglais (eng) Mots-clés : centrifugal  impeller;  microturbine  application Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a study on a small centrifugal impeller for microturbine application from a manufacturing perspective. The aim is to analyze the impact of geometric deviations on part performance using adequate performance modeling tools and statistical methods. A one-dimensional (1D) performance analysis tool was developed in-house derived from the meanline and two-zone modeling methods. The 1D model proved to be a simple and computationally inexpensive tool for having a quick performance analysis of the impeller using basic geometric information extracted from part drawings. For the sensitivity analysis, a total of eight input geometric parameters, including radii, tip-clearance, and blade angles, were varied individually within specific limits in the 1D tool for classifying their influence on the output performance. Since the 1D model is a simplified version of a much more complex three-dimensional (3D) model, a commercial computational fluid dynamics (CFD) tool was used to provide a comparison with the 1D model and scrutinize the effects of such deviations on the fluid behavior inside the impeller passage at a detailed level. For uncertainty quantification, Monte Carlo simulation was performed using the 1D model to assess the variability of overall impeller output performance to simultaneous random deviations in the input geometric parameters. The study is useful to evaluate the possibility of designing gas turbine parts for manufacturability and superior production cost-effectiveness. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000010 [...] [article] Effects of manufacturing noise on microturbine centrifugal impeller performance [texte imprimé] / A. Javed, Auteur ; R. Pecnik, Auteur ; M. Olivero, Auteur . - 2012 . - 09 p. gas turbines Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 10 (Octobre 2012) . - 09 p. Mots-clés : centrifugal  impeller;  microturbine  application Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a study on a small centrifugal impeller for microturbine application from a manufacturing perspective. The aim is to analyze the impact of geometric deviations on part performance using adequate performance modeling tools and statistical methods. A one-dimensional (1D) performance analysis tool was developed in-house derived from the meanline and two-zone modeling methods. The 1D model proved to be a simple and computationally inexpensive tool for having a quick performance analysis of the impeller using basic geometric information extracted from part drawings. For the sensitivity analysis, a total of eight input geometric parameters, including radii, tip-clearance, and blade angles, were varied individually within specific limits in the 1D tool for classifying their influence on the output performance. Since the 1D model is a simplified version of a much more complex three-dimensional (3D) model, a commercial computational fluid dynamics (CFD) tool was used to provide a comparison with the 1D model and scrutinize the effects of such deviations on the fluid behavior inside the impeller passage at a detailed level. For uncertainty quantification, Monte Carlo simulation was performed using the 1D model to assess the variability of overall impeller output performance to simultaneous random deviations in the input geometric parameters. The study is useful to evaluate the possibility of designing gas turbine parts for manufacturability and superior production cost-effectiveness. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000010 [...]