Documents disponibles écrits par cet auteur

Elastic stiffness comparisons between RBS beams with either flange or web reductions / Yousef Ashrafi in Journal of structural engineering, Vol. 138 N° 7 (Juillet 2012) 

Public ISBD [article]  in Journal of structural engineering > Vol. 138 N° 7 (Juillet 2012) . - pp. 961–966 Titre : Elastic stiffness comparisons between RBS beams with either flange or web reductions Type de document : texte imprimé Auteurs : Yousef Ashrafi, Auteur ; Behzad Rafezy, Auteur Année de publication : 2012 Article en page(s) : pp. 961–966 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Beams  Frames  Reduced  section  Elastic  stiffness  Exact  finite  element  Connections  Earthquakes Résumé : This paper compares the elastic stiffness of reduced beam section (RBS) beams with either flange or web reductions. The former has received considerable attention. However, recently the latter has been shown to have superior plastic rotation capacity and energy dissipation characteristics and is generally more amenable to retrofitting strategies. Initially, a closed-form elastic stiffness matrix for a RBS beam with web reduction is derived from first principles. Its performance is then compared with its reduced flange counterpart using data that are available in the literature. The differences between the two approaches are highlighted in a small parametric study. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000429 [article] Elastic stiffness comparisons between RBS beams with either flange or web reductions [texte imprimé] / Yousef Ashrafi, Auteur ; Behzad Rafezy, Auteur . - 2012 . - pp. 961–966. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 138 N° 7 (Juillet 2012) . - pp. 961–966 Mots-clés : Beams  Frames  Reduced  section  Elastic  stiffness  Exact  finite  element  Connections  Earthquakes Résumé : This paper compares the elastic stiffness of reduced beam section (RBS) beams with either flange or web reductions. The former has received considerable attention. However, recently the latter has been shown to have superior plastic rotation capacity and energy dissipation characteristics and is generally more amenable to retrofitting strategies. Initially, a closed-form elastic stiffness matrix for a RBS beam with web reduction is derived from first principles. Its performance is then compared with its reduced flange counterpart using data that are available in the literature. The differences between the two approaches are highlighted in a small parametric study. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000429

Particle dynamics in a chemical vapor deposition reactor / Yousef Ashrafi in Industrial & engineering chemistry research, Vol. 48 N° 13 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 5969–5974 Titre : Particle dynamics in a chemical vapor deposition reactor : a multiscale approach Type de document : texte imprimé Auteurs : Yousef Ashrafi, Auteur ; Luke Achenie, Auteur Année de publication : 2009 Article en page(s) : pp. 5969–5974 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Zinc  sulfide  Chemical  vapor  deposition  method  Deposited  film Résumé : Compared to other semiconductors, zinc sulfide has a large direct band gap which makes it useful in a broad range of optical applications which demand high quality zinc sulfide films which are produced through the chemical vapor deposition method. In order to achieve high quality films with low defects, a better understanding of the deposition process is necessary. A common cause of defects in the deposited film is due to the fact that the morphology of adducts in the gas phase is different from that of the deposited film. These adducts affect the deposition efficiency and film quality. This paper strives to understand the impact of adducts through a multiscale modeling approach which is used to explain the possible link between the cluster size and the morphological defects on the deposited film. This understanding can be used within a simulation framework to optimize reaction conditions that minimize film defects. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015522 [article] Particle dynamics in a chemical vapor deposition reactor : a multiscale approach [texte imprimé] / Yousef Ashrafi, Auteur ; Luke Achenie, Auteur . - 2009 . - pp. 5969–5974. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 5969–5974 Mots-clés : Zinc  sulfide  Chemical  vapor  deposition  method  Deposited  film Résumé : Compared to other semiconductors, zinc sulfide has a large direct band gap which makes it useful in a broad range of optical applications which demand high quality zinc sulfide films which are produced through the chemical vapor deposition method. In order to achieve high quality films with low defects, a better understanding of the deposition process is necessary. A common cause of defects in the deposited film is due to the fact that the morphology of adducts in the gas phase is different from that of the deposited film. These adducts affect the deposition efficiency and film quality. This paper strives to understand the impact of adducts through a multiscale modeling approach which is used to explain the possible link between the cluster size and the morphological defects on the deposited film. This understanding can be used within a simulation framework to optimize reaction conditions that minimize film defects. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8015522