Documents disponibles écrits par cet auteur

In-plane elastic buckling of shallow parabolic arches under an external load and temperature changes / Jianguo Cai in Journal of structural engineering, Vol. 138 N° 11 (Novembre 2012) 

Public ISBD [article]  in Journal of structural engineering > Vol. 138 N° 11 (Novembre 2012) . - pp. 1300-1309 Titre : In-plane elastic buckling of shallow parabolic arches under an external load and temperature changes Type de document : texte imprimé Auteurs : Jianguo Cai, Auteur ; Yixiang Xu, Auteur ; Jian Feng, Auteur Année de publication : 2013 Article en page(s) : pp. 1300-1309 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Arch  Steel  Buckling  Stability  Temperature  gradients  Temperature  field Résumé : This paper studies the in-plane stability of rotationally restrained shallow arches subjected to a vertical uniform load and temperature changes below 100°C. The virtual work principle method was used to establish the nonlinear equilibrium and buckling equations. Analytical solutions for the nonlinear in-plane symmetric snap-through and asymmetric bifurcation critical loads are obtained. Then the effects of the uniform temperature field and temperature gradients on the in-plane stability for arches are studied. The influence of temperature variations on the critical loads for both the symmetric snap-through and asymmetric bifurcation modes was significant. The critical loads increase with an increase of the uniform temperature field and a decrease of temperature gradients. Furthermore, the effect of temperature changes on the critical load increases with the span-rise ratio m of arches. Increasing the stiffness of the rotational springs will increase the effect of the uniform temperature field but reduce the effect of the temperature gradients. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000570 [article] In-plane elastic buckling of shallow parabolic arches under an external load and temperature changes [texte imprimé] / Jianguo Cai, Auteur ; Yixiang Xu, Auteur ; Jian Feng, Auteur . - 2013 . - pp. 1300-1309. Génie Civil Langues : Anglais (eng) in Journal of structural engineering > Vol. 138 N° 11 (Novembre 2012) . - pp. 1300-1309 Mots-clés : Arch  Steel  Buckling  Stability  Temperature  gradients  Temperature  field Résumé : This paper studies the in-plane stability of rotationally restrained shallow arches subjected to a vertical uniform load and temperature changes below 100°C. The virtual work principle method was used to establish the nonlinear equilibrium and buckling equations. Analytical solutions for the nonlinear in-plane symmetric snap-through and asymmetric bifurcation critical loads are obtained. Then the effects of the uniform temperature field and temperature gradients on the in-plane stability for arches are studied. The influence of temperature variations on the critical loads for both the symmetric snap-through and asymmetric bifurcation modes was significant. The critical loads increase with an increase of the uniform temperature field and a decrease of temperature gradients. Furthermore, the effect of temperature changes on the critical load increases with the span-rise ratio m of arches. Increasing the stiffness of the rotational springs will increase the effect of the uniform temperature field but reduce the effect of the temperature gradients. ISSN : 0733-9445 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000570

Toward polymer product design. I. dynamic optimization of average molecular weights and polydispersity index in batch free radical polymerization / Xi Chen in Industrial & engineering chemistry research, Vol. 48 N° 14 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6739–6748 Titre : Toward polymer product design. I. dynamic optimization of average molecular weights and polydispersity index in batch free radical polymerization Type de document : texte imprimé Auteurs : Xi Chen, Auteur ; Chen, Li, Auteur ; Jian Feng, Auteur Année de publication : 2009 Article en page(s) : pp. 6739–6748 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polymer  products  Molecular  weight  distribution  Polydispersity  index  Stickler−Panke−Hamielec  model Résumé : In the polymer industry, product quality is usually determined by the molecular weight distribution of polymer products. We propose a comprehensive study of polymer product design through dynamic optimization of average molecular weights and the polydispersity index in batch free radical polymerization. After analyzing and validating the modified Stickler−Panke−Hamielec (SPH) model, this paper extends the model to achieve product design with a specified polymer molecular weight distribution for various optimization goals. Conversion maximization under isothermal conditions was studied first. We concluded that dynamic optimization is useful to obtain desired products. However, some specifications of polymer molecular weight distribution cannot be achieved under isothermal conditions. Therefore, optimization with piecewise constant temperature profiles was also studied to extend the range of product specifications. Considering the practical requirement for productivity in engineering applications, reaction time minimization with specified conversion was studied with various temperature profiles. Besides the strategy of optimizing the temperature profile, dynamic optimization of initiator feed profiles is also presented. The results show that polymer product design with a specified polymer molecular weight distribution can be achieved using dynamic optimization of the temperature and initiator profiles in a batch reaction. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801844u [article] Toward polymer product design. I. dynamic optimization of average molecular weights and polydispersity index in batch free radical polymerization [texte imprimé] / Xi Chen, Auteur ; Chen, Li, Auteur ; Jian Feng, Auteur . - 2009 . - pp. 6739–6748. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6739–6748 Mots-clés : Polymer  products  Molecular  weight  distribution  Polydispersity  index  Stickler−Panke−Hamielec  model Résumé : In the polymer industry, product quality is usually determined by the molecular weight distribution of polymer products. We propose a comprehensive study of polymer product design through dynamic optimization of average molecular weights and the polydispersity index in batch free radical polymerization. After analyzing and validating the modified Stickler−Panke−Hamielec (SPH) model, this paper extends the model to achieve product design with a specified polymer molecular weight distribution for various optimization goals. Conversion maximization under isothermal conditions was studied first. We concluded that dynamic optimization is useful to obtain desired products. However, some specifications of polymer molecular weight distribution cannot be achieved under isothermal conditions. Therefore, optimization with piecewise constant temperature profiles was also studied to extend the range of product specifications. Considering the practical requirement for productivity in engineering applications, reaction time minimization with specified conversion was studied with various temperature profiles. Besides the strategy of optimizing the temperature profile, dynamic optimization of initiator feed profiles is also presented. The results show that polymer product design with a specified polymer molecular weight distribution can be achieved using dynamic optimization of the temperature and initiator profiles in a batch reaction. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801844u