Documents disponibles écrits par cet auteur

Efficient numerical solver for partially structured differential and algebraic equation systems / Flavio Manenti in Industrial & engineering chemistry research, Vol. 48 N° 22 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 22 (Novembre 2009) . - pp. 9979–9984 Titre : Efficient numerical solver for partially structured differential and algebraic equation systems Type de document : texte imprimé Auteurs : Flavio Manenti, Auteur ; Ivan Dones, Auteur ; Guido Buzzi-Ferraris, Auteur Année de publication : 2010 Article en page(s) : pp. 9979–9984 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Differential  and  algebraic  equations  Sparse  set Résumé : Given a sparse set of differential and algebraic equations (DAEs), it is always recommended to exploit the structure of the system’s sparsity (e.g., tridiagonal blocks matrix, band matrix, and staircase matrix, etc.), thus to use tailored numerical solvers in order to reduce the computation time. Very frequently, though, while highly structured, a couple of elements enter the description which make it difficult for the solvers to reach a solution. They are common in process control applications, where the states added to the plant description by the integral parts of the controllers introduce unstructured elements in the otherwise very structured Jacobian of the mathematical model. Such systems are characterized by a partially structured Jacobian, which inhibits the use of the solvers tailored to fit problems with fully structured matrices. In such cases, one can either use a solver with lower performance, resulting in larger computation times, or alternatively one seeks an approximation for the unstructured points. A solution to the handling of “dirty” Jacobians is presented, which is implemented in a DAE solver package available freely on the Internet. This novel DAE solver fully exploits the overall structure of the system’s sparsity, without compromising CPU computation time and precision of the results. A numerical comparison with different approaches is given by solving a DAE model representing an existing nonequilibrium distillation column. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9007908 [article] Efficient numerical solver for partially structured differential and algebraic equation systems [texte imprimé] / Flavio Manenti, Auteur ; Ivan Dones, Auteur ; Guido Buzzi-Ferraris, Auteur . - 2010 . - pp. 9979–9984. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 22 (Novembre 2009) . - pp. 9979–9984 Mots-clés : Differential  and  algebraic  equations  Sparse  set Résumé : Given a sparse set of differential and algebraic equations (DAEs), it is always recommended to exploit the structure of the system’s sparsity (e.g., tridiagonal blocks matrix, band matrix, and staircase matrix, etc.), thus to use tailored numerical solvers in order to reduce the computation time. Very frequently, though, while highly structured, a couple of elements enter the description which make it difficult for the solvers to reach a solution. They are common in process control applications, where the states added to the plant description by the integral parts of the controllers introduce unstructured elements in the otherwise very structured Jacobian of the mathematical model. Such systems are characterized by a partially structured Jacobian, which inhibits the use of the solvers tailored to fit problems with fully structured matrices. In such cases, one can either use a solver with lower performance, resulting in larger computation times, or alternatively one seeks an approximation for the unstructured points. A solution to the handling of “dirty” Jacobians is presented, which is implemented in a DAE solver package available freely on the Internet. This novel DAE solver fully exploits the overall structure of the system’s sparsity, without compromising CPU computation time and precision of the results. A numerical comparison with different approaches is given by solving a DAE model representing an existing nonequilibrium distillation column. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9007908

Linear programming with the attic method / Guido Buzzi-Ferraris in Industrial & engineering chemistry research, Vol. 50 N° 9 (Mai 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 9 (Mai 2011) . - pp. 4858-4878 Titre : Linear programming with the attic method Type de document : texte imprimé Auteurs : Guido Buzzi-Ferraris, Auteur Année de publication : 2011 Article en page(s) : pp. 4858-4878 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Mathematical  programming  Linear  programming Résumé : This manuscript outlines a novel approach to solving linear programming problems which is referred to as the Attic Method as it deals with constraints as if they were tiles of a roof. This new approach is conceptually different from both Simplex and Interior Point algorithm families. It is also intrinsically efficient: the computational effort of each iteration is usually smaller since the working matrix may be smaller and its factorization is higher performance especially with respect to Interior Point methods; the number of iterations are usually smaller too, especially compared to the Simplex method; degeneracy and feasible starting point selection problems are also easier to solve. Certain examples illustrate the differences between the Attic and the existing methods. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24128620 [article] Linear programming with the attic method [texte imprimé] / Guido Buzzi-Ferraris, Auteur . - 2011 . - pp. 4858-4878. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 9 (Mai 2011) . - pp. 4858-4878 Mots-clés : Mathematical  programming  Linear  programming Résumé : This manuscript outlines a novel approach to solving linear programming problems which is referred to as the Attic Method as it deals with constraints as if they were tiles of a roof. This new approach is conceptually different from both Simplex and Interior Point algorithm families. It is also intrinsically efficient: the computational effort of each iteration is usually smaller since the working matrix may be smaller and its factorization is higher performance especially with respect to Interior Point methods; the number of iterations are usually smaller too, especially compared to the Simplex method; degeneracy and feasible starting point selection problems are also easier to solve. Certain examples illustrate the differences between the Attic and the existing methods. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24128620