Documents disponibles écrits par cet auteur

Fast high-resolution method for solving multidimensional population balances in crystallization / Aniruddha Majumder in Industrial & engineering chemistry research, Vol. 49 N° 8 (Avril 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 8 (Avril 2010) . - pp. 3862–3872 Titre : Fast high-resolution method for solving multidimensional population balances in crystallization Type de document : texte imprimé Auteurs : Aniruddha Majumder, Auteur ; Vinay Kariwala, Auteur ; Santosh Ansumali, Auteur Année de publication : 2010 Article en page(s) : pp. 3862–3872 Note générale : Industriay Chemistry Langues : Anglais (eng) Mots-clés : Multidimensional  Population  Balances  Crystallization Résumé : High-resolution (HR) finite-volume methods can provide an accurate numerical solution of population balance equations describing crystallization processes. To satisfy the stability requirements, the time step (Δt) for the available HR methods needs to be selected conservatively, rendering them computationally expensive for processes with size-dependent growth rates. In this paper, we propose a coordinate transformation scheme to improve the solution time of HR methods applied to batch crystallization processes with nucleation and size-dependent growth. The coordinate transform takes advantage of the functional form that is used to describe the size dependency of the growth rate. Using benchmark examples, we demonstrate that the proposed method provides a more significant reduction in the solution time than existing HR methods, while retaining the same level of accuracy. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9016946 [article] Fast high-resolution method for solving multidimensional population balances in crystallization [texte imprimé] / Aniruddha Majumder, Auteur ; Vinay Kariwala, Auteur ; Santosh Ansumali, Auteur . - 2010 . - pp. 3862–3872. Industriay Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 8 (Avril 2010) . - pp. 3862–3872 Mots-clés : Multidimensional  Population  Balances  Crystallization Résumé : High-resolution (HR) finite-volume methods can provide an accurate numerical solution of population balance equations describing crystallization processes. To satisfy the stability requirements, the time step (Δt) for the available HR methods needs to be selected conservatively, rendering them computationally expensive for processes with size-dependent growth rates. In this paper, we propose a coordinate transformation scheme to improve the solution time of HR methods applied to batch crystallization processes with nucleation and size-dependent growth. The coordinate transform takes advantage of the functional form that is used to describe the size dependency of the growth rate. Using benchmark examples, we demonstrate that the proposed method provides a more significant reduction in the solution time than existing HR methods, while retaining the same level of accuracy. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9016946

Minimum variance benchmark for performance assessment of decentralized controllers / Antonius Yudi Sendjaja in Industrial & engineering chemistry research, Vol. 51 N° 11 (Mars 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 11 (Mars 2012) . - pp. 4288-4298 Titre : Minimum variance benchmark for performance assessment of decentralized controllers Type de document : texte imprimé Auteurs : Antonius Yudi Sendjaja, Auteur ; Vinay Kariwala, Auteur Année de publication : 2012 Article en page(s) : pp. 4288-4298 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Benchmarks Résumé : The available minimum variance (MV) benchmarks do not take the controller structure into account and thus can lead to incorrect conclusions regarding the performance of decentralized controllers. In this paper, we present a method for computing a lower bound on the least output variance achievable using decentralized controllers, where the nonconvexity of the optimization problem is handled using sums of squares programming. Though tight, the computation of this lower bound requires that the process model be known. As a more practical approach, we derive an MV benchmark for performance assessment of decentralized controllers on a loop by loop basis. The MV benchmark for loop by loop analysis can be estimated from the closed loop operating data with the knowledge of time delays between all the inputs and outputs. The usefulness of the proposed benchmarks is demonstrated using simulation examples. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25655638 [article] Minimum variance benchmark for performance assessment of decentralized controllers [texte imprimé] / Antonius Yudi Sendjaja, Auteur ; Vinay Kariwala, Auteur . - 2012 . - pp. 4288-4298. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 11 (Mars 2012) . - pp. 4288-4298 Mots-clés : Benchmarks Résumé : The available minimum variance (MV) benchmarks do not take the controller structure into account and thus can lead to incorrect conclusions regarding the performance of decentralized controllers. In this paper, we present a method for computing a lower bound on the least output variance achievable using decentralized controllers, where the nonconvexity of the optimization problem is handled using sums of squares programming. Though tight, the computation of this lower bound requires that the process model be known. As a more practical approach, we derive an MV benchmark for performance assessment of decentralized controllers on a loop by loop basis. The MV benchmark for loop by loop analysis can be estimated from the closed loop operating data with the knowledge of time delays between all the inputs and outputs. The usefulness of the proposed benchmarks is demonstrated using simulation examples. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25655638

Multiobjective control structure design / Vinay Kariwala in Industrial & engineering chemistry research, Vol. 51 N° 17 (Mai 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 17 (Mai 2012) . - pp. 6064–6070 Titre : Multiobjective control structure design : A branch and bound approach Type de document : texte imprimé Auteurs : Vinay Kariwala, Auteur ; Yi Cao, Auteur Année de publication : 2012 Article en page(s) : pp. 6064–6070 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Multiobjective  optimization Résumé : Control structure design traditionally involves two steps of selections, namely the selection of controlled and manipulated variables and the selection of pairings interconnecting these variables. The available criteria for both selections require enumeration of every alternative. Hence, an exhaustive search can be computationally forbidding for large-scale processes. On the other hand, owing to the computational complexity, variables and pairings are often selected sequentially, which may result in suboptimal control structures. In this paper, an efficient branch and bound (BAB) method is proposed to select the variables and pairings together in a multiobjective optimization framework. As an illustration of the proposed multiobjective BAB framework, the minimum singular value rule and the μ-interaction measure are used as the criteria for selection of controlled variables and pairings, respectively. Numerical tests using randomly generated matrices and the large-scale case study of hydrodealkylation of toluene (HDA) process show that the BAB method is able to reduce the solution time by several orders of magnitude in comparison with exhaustive search. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201510c [article] Multiobjective control structure design : A branch and bound approach [texte imprimé] / Vinay Kariwala, Auteur ; Yi Cao, Auteur . - 2012 . - pp. 6064–6070. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 17 (Mai 2012) . - pp. 6064–6070 Mots-clés : Multiobjective  optimization Résumé : Control structure design traditionally involves two steps of selections, namely the selection of controlled and manipulated variables and the selection of pairings interconnecting these variables. The available criteria for both selections require enumeration of every alternative. Hence, an exhaustive search can be computationally forbidding for large-scale processes. On the other hand, owing to the computational complexity, variables and pairings are often selected sequentially, which may result in suboptimal control structures. In this paper, an efficient branch and bound (BAB) method is proposed to select the variables and pairings together in a multiobjective optimization framework. As an illustration of the proposed multiobjective BAB framework, the minimum singular value rule and the μ-interaction measure are used as the criteria for selection of controlled variables and pairings, respectively. Numerical tests using randomly generated matrices and the large-scale case study of hydrodealkylation of toluene (HDA) process show that the BAB method is able to reduce the solution time by several orders of magnitude in comparison with exhaustive search. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201510c