Documents disponibles écrits par cet auteur

Simultaneous determination of the surface tension and density of polystyrene in supercritical nitrogen / H. Park in Industrial & engineering chemistry research, Vol. 47 N° 13 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4369–4373 Titre : Simultaneous determination of the surface tension and density of polystyrene in supercritical nitrogen Type de document : texte imprimé Auteurs : H. Park, Auteur ; C. B. Park, Auteur ; C. Tzoganakis, Auteur ; K. H. Tan, Auteur Année de publication : 2008 Article en page(s) : p. 4369–4373 Note générale : Bibliogr. p. 4373 Langues : Anglais (eng) Mots-clés : Polymers  --  polystyrene;  Density;  Surface  tension Résumé : In this paper we present a simple procedure for calculating the mass density of polymers at high temperature and pressure conditions. The proposed method entails the integration of a pendant drop volume from an axisymmetric drop image profile; this same pendant drop profile can be used to determine the surface tension using axisymmetric drop shape analysis (ADSA). Our approach yields both density and surface tension data simultaneously and is advantageous since it does not require any additional procedure or module to calculate the density of polymers in a fluid. This integration method provides a set of density data for the sample polymer, polystyrene, in supercritical fluid nitrogen, which is similar to the data derived from the empirical Tait equation and the semiempirical Sanchez−Lacombe equation of state when the temperature is above the polymer glass transition point. The results corroborate the use of all three approaches in determining the mass density of polymers at high temperatures. The comparable surface tension data are obtained at temperatures above the glass transition temperature of polymer with the densities generated by the three density determination approaches. We expect that the approach based on ADSA in conjunction with the mass density determination by the current integration method can be applied to the surface tension measurements of many other polymer melts in various fluid environments. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071472q [article] Simultaneous determination of the surface tension and density of polystyrene in supercritical nitrogen [texte imprimé] / H. Park, Auteur ; C. B. Park, Auteur ; C. Tzoganakis, Auteur ; K. H. Tan, Auteur . - 2008 . - p. 4369–4373. Bibliogr. p. 4373 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4369–4373 Mots-clés : Polymers  --  polystyrene;  Density;  Surface  tension Résumé : In this paper we present a simple procedure for calculating the mass density of polymers at high temperature and pressure conditions. The proposed method entails the integration of a pendant drop volume from an axisymmetric drop image profile; this same pendant drop profile can be used to determine the surface tension using axisymmetric drop shape analysis (ADSA). Our approach yields both density and surface tension data simultaneously and is advantageous since it does not require any additional procedure or module to calculate the density of polymers in a fluid. This integration method provides a set of density data for the sample polymer, polystyrene, in supercritical fluid nitrogen, which is similar to the data derived from the empirical Tait equation and the semiempirical Sanchez−Lacombe equation of state when the temperature is above the polymer glass transition point. The results corroborate the use of all three approaches in determining the mass density of polymers at high temperatures. The comparable surface tension data are obtained at temperatures above the glass transition temperature of polymer with the densities generated by the three density determination approaches. We expect that the approach based on ADSA in conjunction with the mass density determination by the current integration method can be applied to the surface tension measurements of many other polymer melts in various fluid environments. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071472q

Structural behavior of CHS T-joints subjected to brace axial compression in fire conditions / K. H. Tan in Journal of structural engineering, Vol. 139 N° 1 (Janvier 2013) 

Public ISBD [article]  in Journal of structural engineering > Vol. 139 N° 1 (Janvier 2013) . - pp. 73–84 Titre : Structural behavior of CHS T-joints subjected to brace axial compression in fire conditions Type de document : texte imprimé Auteurs : K. H. Tan, Auteur ; T. C. Fung, Auteur ; M. P. Nguyen, Auteur Année de publication : 2013 Article en page(s) : pp. 73–84 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : CHS  T-joints  Ultimate  strength  Experimental  study  Fire  Brace  axial  compression  Finite-element  models Résumé : The structural behavior of circular hollow section (CHS) T-joints subjected to axial brace compression in fire conditions was investigated. Five full-scale tubular joints with different brace-to-chord diameter ratios were tested under elevated temperature. The tests were in isothermal heating conditions, where the specimens were heated to the desired temperatures and then subjected to static load to failure. The ultimate strength and failure modes of these joints were investigated. It was observed that both the reduction in material strength and changes in localized plastification area beneath the brace decreased the ultimate strength of the joints as temperature increased. Furthermore, local buckling and ovalisation of the chords were found to be more concentrated around the joint region at elevated temperature. To the authors’ best knowledge, these tests were among the first reported experimental investigations in the ultimate strength and failure mechanisms of tubular joints at elevated temperature. To investigate the joint behavior at high temperature in greater detail, FEM was used. The finite-element models were first validated by the test results. The development of failure mechanisms of CHS T-joints at elevated temperature was then traced with the numerical models. The models were also used to quantify the effect of elevated temperatures on three parameters that directly affect the ultimate strength of the T-joints. The three parameters are boundary condition, precompression in the chord, and chord thickness. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000604 [article] Structural behavior of CHS T-joints subjected to brace axial compression in fire conditions [texte imprimé] / K. H. Tan, Auteur ; T. C. Fung, Auteur ; M. P. Nguyen, Auteur . - 2013 . - pp. 73–84. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 139 N° 1 (Janvier 2013) . - pp. 73–84 Mots-clés : CHS  T-joints  Ultimate  strength  Experimental  study  Fire  Brace  axial  compression  Finite-element  models Résumé : The structural behavior of circular hollow section (CHS) T-joints subjected to axial brace compression in fire conditions was investigated. Five full-scale tubular joints with different brace-to-chord diameter ratios were tested under elevated temperature. The tests were in isothermal heating conditions, where the specimens were heated to the desired temperatures and then subjected to static load to failure. The ultimate strength and failure modes of these joints were investigated. It was observed that both the reduction in material strength and changes in localized plastification area beneath the brace decreased the ultimate strength of the joints as temperature increased. Furthermore, local buckling and ovalisation of the chords were found to be more concentrated around the joint region at elevated temperature. To the authors’ best knowledge, these tests were among the first reported experimental investigations in the ultimate strength and failure mechanisms of tubular joints at elevated temperature. To investigate the joint behavior at high temperature in greater detail, FEM was used. The finite-element models were first validated by the test results. The development of failure mechanisms of CHS T-joints at elevated temperature was then traced with the numerical models. The models were also used to quantify the effect of elevated temperatures on three parameters that directly affect the ultimate strength of the T-joints. The three parameters are boundary condition, precompression in the chord, and chord thickness. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000604