Documents disponibles écrits par cet auteur

An efficient numerical method for solving a model describing crystallization of polymorphs / Shamsul Qamar in Industrial & engineering chemistry research, Vol. 49 N° 10 (Mai 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 10 (Mai 2010) . - pp. 4940–4947 Titre : An efficient numerical method for solving a model describing crystallization of polymorphs Type de document : texte imprimé Auteurs : Shamsul Qamar, Auteur ; Saima Noor, Auteur ; Andreas Seidel - Morgenstern, Auteur Année de publication : 2010 Article en page(s) : pp. 4940–4947 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Crystallization  Polymorphs Résumé : Polymorphism, in which a chemical compound exhibits different crystal forms or structures, has significant influence on the processing and storage of some crystalline powders in pharmaceutical industry. Different crystal structures, the so-called polymorphs, have different physical and chemical properties, such as crystal morphology, solubility, and color. These properties can have profound effect on the performance of products. This fact has motivated several researchers in this field to analyze, simulate, and control the crystallization of polymorphs. In this article, an efficient and accurate numerical method is introduced for solving a model describing crystallization of polymorphs. The proposed method has two parts. In the first part, a coupled system of ordinary differential equations of moments and the solute concentration is numerically solved in the time domain of interest. The resulting values are used to get the discrete growth and nucleation rates in the same time domain. In the second part, these discrete values along with the initial crystal size distribution (CSD) are used to construct the final CSD. The method is applied to a model describing crystallization of polymorphs of l-glutamic acid. For a validation, the results of the proposed technique are compared with those from the finite volume schemes. The numerical results demonstrate the potential of our scheme for the simulation of current model with high efficiency and accuracy. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9018353 [article] An efficient numerical method for solving a model describing crystallization of polymorphs [texte imprimé] / Shamsul Qamar, Auteur ; Saima Noor, Auteur ; Andreas Seidel - Morgenstern, Auteur . - 2010 . - pp. 4940–4947. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 10 (Mai 2010) . - pp. 4940–4947 Mots-clés : Crystallization  Polymorphs Résumé : Polymorphism, in which a chemical compound exhibits different crystal forms or structures, has significant influence on the processing and storage of some crystalline powders in pharmaceutical industry. Different crystal structures, the so-called polymorphs, have different physical and chemical properties, such as crystal morphology, solubility, and color. These properties can have profound effect on the performance of products. This fact has motivated several researchers in this field to analyze, simulate, and control the crystallization of polymorphs. In this article, an efficient and accurate numerical method is introduced for solving a model describing crystallization of polymorphs. The proposed method has two parts. In the first part, a coupled system of ordinary differential equations of moments and the solute concentration is numerically solved in the time domain of interest. The resulting values are used to get the discrete growth and nucleation rates in the same time domain. In the second part, these discrete values along with the initial crystal size distribution (CSD) are used to construct the final CSD. The method is applied to a model describing crystallization of polymorphs of l-glutamic acid. For a validation, the results of the proposed technique are compared with those from the finite volume schemes. The numerical results demonstrate the potential of our scheme for the simulation of current model with high efficiency and accuracy. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9018353

Bivariate extension of the quadrature method of moments for batch crystallization models / Shamsul Qamar in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11633-11644 Titre : Bivariate extension of the quadrature method of moments for batch crystallization models Type de document : texte imprimé Auteurs : Shamsul Qamar, Auteur ; Saima Noor, Auteur ; Qurrat ul Ain, Auteur Année de publication : 2011 Article en page(s) : pp. 11633-11644 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Modeling  Crystallization  Batchwise Résumé : This Article presents a bivariate extension of the quadrature method of moments for solving two-dimensional batch crystallization models involving crystals nucleation, size-dependent growths, aggregation, and dissolution of small nuclei below certain critical size in a dissolution unit. In this technique, orthogonal polynomials of lower order moments are used to find the quadrature abscissas (points) and weights. Several benchmark problems with different combinations of processes are considered in this Article. The accuracy and efficiency of the proposed method are validated against the analytical solutions and the high-resolution finite volume scheme. Excellent agreements were observed in all test problems. It was found that the current method is very efficient and accurate as compared to the high-resolution finite volume scheme. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23437862 [article] Bivariate extension of the quadrature method of moments for batch crystallization models [texte imprimé] / Shamsul Qamar, Auteur ; Saima Noor, Auteur ; Qurrat ul Ain, Auteur . - 2011 . - pp. 11633-11644. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11633-11644 Mots-clés : Modeling  Crystallization  Batchwise Résumé : This Article presents a bivariate extension of the quadrature method of moments for solving two-dimensional batch crystallization models involving crystals nucleation, size-dependent growths, aggregation, and dissolution of small nuclei below certain critical size in a dissolution unit. In this technique, orthogonal polynomials of lower order moments are used to find the quadrature abscissas (points) and weights. Several benchmark problems with different combinations of processes are considered in this Article. The accuracy and efficiency of the proposed method are validated against the analytical solutions and the high-resolution finite volume scheme. Excellent agreements were observed in all test problems. It was found that the current method is very efficient and accurate as compared to the high-resolution finite volume scheme. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23437862