Documents disponibles écrits par cet auteur

Identification of Markov Matrices of Milling Models / Jayanta Chakraborty in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9763–9771 Titre : Identification of Markov Matrices of Milling Models Type de document : texte imprimé Auteurs : Jayanta Chakraborty, Auteur ; Doraiswami Ramkrishna, Auteur Année de publication : 2010 Article en page(s) : pp. 9763–9771 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Grinding  mill  Markov  chain  models Résumé : Detailed modeling of a grinding mill can be achieved through Markov chain models without involving lengthy computations. However, estimation of the key parameters of the model, elements of the Markov transition matrix, using observable quantities is not trivial. This powerful modeling tool can find wide applicability in operation and control of industrial mills if this set of parameters can be estimated using suitably observed quantities. In this study we model a complex multiregion mill using Markov chain and propose a general technique for estimation of the Markov transition matrix for breakage problems. This technique estimates the transition matrix from observed evolution of particle size distributions in various regions of the mill, based on extracting spectral information of the transition matrix from the data. It has been shown in this study that a specific grouping of states can lead to lower triangular block structure of the Markov transition matrix for a breakage problem. Detailed analysis of such a block matrix reveals that simple semilogarithmic plots of a set of observed quantities can be used in order to extract the spectral information of the transition matrix which in turn can be used to reconstruct the Markov matrix. A numerical example has been presented to illustrate various ideas which demonstrate that the proposed technique can be used successfully to estimate the Markov transition matrix very accurately from observations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900456j#tfn1 [article] Identification of Markov Matrices of Milling Models [texte imprimé] / Jayanta Chakraborty, Auteur ; Doraiswami Ramkrishna, Auteur . - 2010 . - pp. 9763–9771. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9763–9771 Mots-clés : Grinding  mill  Markov  chain  models Résumé : Detailed modeling of a grinding mill can be achieved through Markov chain models without involving lengthy computations. However, estimation of the key parameters of the model, elements of the Markov transition matrix, using observable quantities is not trivial. This powerful modeling tool can find wide applicability in operation and control of industrial mills if this set of parameters can be estimated using suitably observed quantities. In this study we model a complex multiregion mill using Markov chain and propose a general technique for estimation of the Markov transition matrix for breakage problems. This technique estimates the transition matrix from observed evolution of particle size distributions in various regions of the mill, based on extracting spectral information of the transition matrix from the data. It has been shown in this study that a specific grouping of states can lead to lower triangular block structure of the Markov transition matrix for a breakage problem. Detailed analysis of such a block matrix reveals that simple semilogarithmic plots of a set of observed quantities can be used in order to extract the spectral information of the transition matrix which in turn can be used to reconstruct the Markov matrix. A numerical example has been presented to illustrate various ideas which demonstrate that the proposed technique can be used successfully to estimate the Markov transition matrix very accurately from observations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900456j#tfn1

Population balance modeling of environment dependent breakage / Jayanta Chakraborty in Industrial & engineering chemistry research, Vol. 50 N° 23 (Décembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp. 13116–13128 Titre : Population balance modeling of environment dependent breakage : role of granular viscosity, density and compaction. model formulation and similarity analysis Type de document : texte imprimé Auteurs : Jayanta Chakraborty, Auteur ; Doraiswami Ramkrishna, Auteur Année de publication : 2012 Article en page(s) : pp. 13116–13128 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Similarity  Compaction  Density  Viscosity  Modeling  Population  balance Résumé : In this work, we introduce mechanistic considerations in nonlinear milling of particulate material. We show that the mobility of the powder can have a significant effect on the breakage frequency. During grinding, the change in particle size leads to changes in the mobility of the powder which in turn alters the breakage rate. The mechanistic modeling, being able to accommodate different responses of powder mobility for wet and dry grinding, is able to distinguish naturally between dry and wet grinding, an attribute not possessed by other nonlinear models. It is shown that the rich variety of phenomena observed in grinding mills emanates from the interplay between opposing factors that influence the breakage environment in a mill. Such factors include viscosity, density, and compaction of the powder. For dry grinding, the change in powder porosity and viscosity leads to a variety of nonlinear effects. For wet grinding the viscosity and density of the slurry impart a nonmonotonic variation in the breakage rate with particle size. A population balance equation (PBE) for environment dependent breakage has been formulated by considering the foregoing effects. Similarity analysis of the model equation shows the existence of self-similar behavior even for the environment dependent breakage. Experimental investigation of such self-similarity provides an effective diagnostic process for validating model framework. Furthermore, when combined with the methodology of solving inverse problems (e.g., Sathyagal, A. N.; Ramkrishna, D. Chem. Eng. Sci. 1996, 51, 1377), an effective approach becomes available for model identification. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25267469 [article] Population balance modeling of environment dependent breakage : role of granular viscosity, density and compaction. model formulation and similarity analysis [texte imprimé] / Jayanta Chakraborty, Auteur ; Doraiswami Ramkrishna, Auteur . - 2012 . - pp. 13116–13128. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp. 13116–13128 Mots-clés : Similarity  Compaction  Density  Viscosity  Modeling  Population  balance Résumé : In this work, we introduce mechanistic considerations in nonlinear milling of particulate material. We show that the mobility of the powder can have a significant effect on the breakage frequency. During grinding, the change in particle size leads to changes in the mobility of the powder which in turn alters the breakage rate. The mechanistic modeling, being able to accommodate different responses of powder mobility for wet and dry grinding, is able to distinguish naturally between dry and wet grinding, an attribute not possessed by other nonlinear models. It is shown that the rich variety of phenomena observed in grinding mills emanates from the interplay between opposing factors that influence the breakage environment in a mill. Such factors include viscosity, density, and compaction of the powder. For dry grinding, the change in powder porosity and viscosity leads to a variety of nonlinear effects. For wet grinding the viscosity and density of the slurry impart a nonmonotonic variation in the breakage rate with particle size. A population balance equation (PBE) for environment dependent breakage has been formulated by considering the foregoing effects. Similarity analysis of the model equation shows the existence of self-similar behavior even for the environment dependent breakage. Experimental investigation of such self-similarity provides an effective diagnostic process for validating model framework. Furthermore, when combined with the methodology of solving inverse problems (e.g., Sathyagal, A. N.; Ramkrishna, D. Chem. Eng. Sci. 1996, 51, 1377), an effective approach becomes available for model identification. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25267469