Documents disponibles écrits par cet auteur

Cyclic twin nucleation in tin-based solder alloys / L.P. Lehman in Acta materialia, Vol. 58 N° 10 (Juin 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 10 (Juin 2010) . - pp. 3546–3556 Titre : Cyclic twin nucleation in tin-based solder alloys Type de document : texte imprimé Auteurs : L.P. Lehman, Auteur ; Y. Xing, Auteur ; T. R. Bieler, Auteur Année de publication : 2011 Article en page(s) : pp. 3546–3556 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Undercooling  solidification  Nucleation  Twinning  Single  crystal  growth  Electron  backscattering  diffraction  (EBSD)  Solidification  microstructure Résumé : The microstructure and Sn crystal orientations of lead-free solder alloys such as near-eutectic SnAgCu have a significant influence on the mechanical response of a solder joint to service conditions. Thus solidification processes were examined in SnAgCu solder joints. Distinct evidence of sixfold cyclic growth twinning of Sn during solidification from the melt was observed in Sn–Ag, SAC and Sn–Cu solders. Three orientations of Sn grains, each having a common 〈1 0 0〉 direction, were found in each of these systems, though the morphologies of these cyclic twinned microstructures differed. Analysis of dendrite arm spacing in cyclically twined structures with a beach ball morphology implies that the common 〈1 0 0〉 axis intersects with the region of the nucleation event. Models are presented for two pseudo/metastable hexagonal unit cells based upon {1 0 1} or {3 0 1} twins that introduce the cyclic twinning structure at the nucleation stage. Formation of these hexagonal unit cells may be facilitated by the presence of alloy elements. Subsequent epitaxial growth of the tetragonal unit cell on this nucleus can account for all three types of morphologies observed in microstructures of Sn-rich solder alloys. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000443 [article] Cyclic twin nucleation in tin-based solder alloys [texte imprimé] / L.P. Lehman, Auteur ; Y. Xing, Auteur ; T. R. Bieler, Auteur . - 2011 . - pp. 3546–3556. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 10 (Juin 2010) . - pp. 3546–3556 Mots-clés : Undercooling  solidification  Nucleation  Twinning  Single  crystal  growth  Electron  backscattering  diffraction  (EBSD)  Solidification  microstructure Résumé : The microstructure and Sn crystal orientations of lead-free solder alloys such as near-eutectic SnAgCu have a significant influence on the mechanical response of a solder joint to service conditions. Thus solidification processes were examined in SnAgCu solder joints. Distinct evidence of sixfold cyclic growth twinning of Sn during solidification from the melt was observed in Sn–Ag, SAC and Sn–Cu solders. Three orientations of Sn grains, each having a common 〈1 0 0〉 direction, were found in each of these systems, though the morphologies of these cyclic twinned microstructures differed. Analysis of dendrite arm spacing in cyclically twined structures with a beach ball morphology implies that the common 〈1 0 0〉 axis intersects with the region of the nucleation event. Models are presented for two pseudo/metastable hexagonal unit cells based upon {1 0 1} or {3 0 1} twins that introduce the cyclic twinning structure at the nucleation stage. Formation of these hexagonal unit cells may be facilitated by the presence of alloy elements. Subsequent epitaxial growth of the tetragonal unit cell on this nucleus can account for all three types of morphologies observed in microstructures of Sn-rich solder alloys. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000443

Modelling the sustainability of mass tourism in island tourist economies / Y. Xing in Journal of the operational research society (JORS), Vol. 62 N° 9 (Septembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 9 (Septembre 2011) . - pp. 1742–1752 Titre : Modelling the sustainability of mass tourism in island tourist economies Type de document : texte imprimé Auteurs : Y. Xing, Auteur ; B. Dangerfield, Auteur Année de publication : 2011 Article en page(s) : pp. 1742–1752 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : System  dynamics  Sustainable  development  Tourist  economy  Tourism  policy  analysis Index. décimale : 001.424 Résumé : Tourism is one of the world's largest industries and is a source of jobs across national and regional economies. Assessing the economic, environmental and social impacts of tourism development has become a major activity within the tourism and sustainable development communities. The purpose of this research is to demonstrate the contribution of system dynamics for analysing policies that can not only promote sustainable tourism development, but also act as a warning signal to the industry about the potential negative consequences of uncontrolled growth of mass tourism, particularly in island tourist economies. Previous research in the tourism sector has been fragmented, when a holistic approach is needed in order to try to coerce some alignment in the views of the various stakeholders. The main research results illustrated in this paper are: a generic model of a tourism system informed by the (mainly) South European island tourist economies and a set of scenarios illustrating examples of policy analysis. The generic model and the modelling process developed in this research will have some transferability to other issues concerned with policymaking for sustainable development. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n9/abs/jors201077a.html [article] Modelling the sustainability of mass tourism in island tourist economies [texte imprimé] / Y. Xing, Auteur ; B. Dangerfield, Auteur . - 2011 . - pp. 1742–1752. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 9 (Septembre 2011) . - pp. 1742–1752 Mots-clés : System  dynamics  Sustainable  development  Tourist  economy  Tourism  policy  analysis Index. décimale : 001.424 Résumé : Tourism is one of the world's largest industries and is a source of jobs across national and regional economies. Assessing the economic, environmental and social impacts of tourism development has become a major activity within the tourism and sustainable development communities. The purpose of this research is to demonstrate the contribution of system dynamics for analysing policies that can not only promote sustainable tourism development, but also act as a warning signal to the industry about the potential negative consequences of uncontrolled growth of mass tourism, particularly in island tourist economies. Previous research in the tourism sector has been fragmented, when a holistic approach is needed in order to try to coerce some alignment in the views of the various stakeholders. The main research results illustrated in this paper are: a generic model of a tourism system informed by the (mainly) South European island tourist economies and a set of scenarios illustrating examples of policy analysis. The generic model and the modelling process developed in this research will have some transferability to other issues concerned with policymaking for sustainable development. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n9/abs/jors201077a.html