Documents disponibles écrits par cet auteur

Generalized disjunctive programming as a systematic modeling framework to derive scheduling formulations / Pedro M. Castro in Industrial & engineering chemistry research, Vol. 51 N° 16 (Avril 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 16 (Avril 2012) . - pp. 5781–5792 Titre : Generalized disjunctive programming as a systematic modeling framework to derive scheduling formulations Type de document : texte imprimé Auteurs : Pedro M. Castro, Auteur ; Ignacio E. Grossmann, Auteur Année de publication : 2012 Article en page(s) : pp. 5781–5792 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Disjunctive  programming  Scheduling Résumé : We propose linear generalized disjunctive programming (GDP) models for the short-term scheduling problem of single stage batch plants with parallel units. Three different concepts of continuous-time representation are explored, immediate and general precedence, as well as multiple time grids. The linear GDP models are then reformulated using both big-M and convex hull reformulations, and the resulting mixed-integer linear programming models compared through the solution of a set of example problems. We show that two general precedence models from the literature can be derived using a big-M reformulation for a set of disjunctions and a convex hull reformulation for another. The best performer is, however, a multiple time grid model which can be derived from the convex hull reformulation followed by simple algebraic manipulations to eliminate the disaggregated variables and reduce the sets of constraints, thus leading to a more compact and efficient formulation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2030486 [article] Generalized disjunctive programming as a systematic modeling framework to derive scheduling formulations [texte imprimé] / Pedro M. Castro, Auteur ; Ignacio E. Grossmann, Auteur . - 2012 . - pp. 5781–5792. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 16 (Avril 2012) . - pp. 5781–5792 Mots-clés : Disjunctive  programming  Scheduling Résumé : We propose linear generalized disjunctive programming (GDP) models for the short-term scheduling problem of single stage batch plants with parallel units. Three different concepts of continuous-time representation are explored, immediate and general precedence, as well as multiple time grids. The linear GDP models are then reformulated using both big-M and convex hull reformulations, and the resulting mixed-integer linear programming models compared through the solution of a set of example problems. We show that two general precedence models from the literature can be derived using a big-M reformulation for a set of disjunctions and a convex hull reformulation for another. The best performer is, however, a multiple time grid model which can be derived from the convex hull reformulation followed by simple algebraic manipulations to eliminate the disaggregated variables and reduce the sets of constraints, thus leading to a more compact and efficient formulation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2030486

Hybrid mathematical programming discrete-event simulation approach for large-scale scheduling problems / Pedro M. Castro in Industrial & engineering chemistry research, Vol. 50 N° 18 (Septembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10665-10680 Titre : Hybrid mathematical programming discrete-event simulation approach for large-scale scheduling problems Type de document : texte imprimé Auteurs : Pedro M. Castro, Auteur ; Adrian M. Aguirre, Auteur ; Luis J. Zeballos, Auteur Année de publication : 2011 Article en page(s) : pp. 10665-10680 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Scheduling  Mathematical  programming Résumé : This article presents a new algorithm for industrially sized problems that, because of the large number of tasks to schedule, are either intractable or result in poor solutions when solved with full-space mathematical programming approaches. Focus is set on a special type of multistage batch plant featuring a single unit per stage, zero-wait storage policies, and a single transportation device for moving lots between stages. The algorithm incorporates a mixed-integer linear programming (MILP) continuous-time formulation and a discrete-event simulation model to generate a detailed schedule. More precisely, three stages are involved: (i) finding the best processing sequence, assuming that the transportation device is always available; (ii) generating a feasible schedule, taking into account the shared transportation resource; (iii) improving the schedule through a neighborhood search procedure. Relaxed and constrained versions of the full-space MILP are involved in stages (i) and (iii) with the simulation model taking care of stage (ii). Several examples are solved to illustrate the capabilities of the proposed method with the results showing better performance when compared to other published approaches. The balance between solution quality and total computational effort can easily be shifted by changing the number of lots rescheduled per iteration. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523885 [article] Hybrid mathematical programming discrete-event simulation approach for large-scale scheduling problems [texte imprimé] / Pedro M. Castro, Auteur ; Adrian M. Aguirre, Auteur ; Luis J. Zeballos, Auteur . - 2011 . - pp. 10665-10680. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 18 (Septembre 2011) . - pp. 10665-10680 Mots-clés : Scheduling  Mathematical  programming Résumé : This article presents a new algorithm for industrially sized problems that, because of the large number of tasks to schedule, are either intractable or result in poor solutions when solved with full-space mathematical programming approaches. Focus is set on a special type of multistage batch plant featuring a single unit per stage, zero-wait storage policies, and a single transportation device for moving lots between stages. The algorithm incorporates a mixed-integer linear programming (MILP) continuous-time formulation and a discrete-event simulation model to generate a detailed schedule. More precisely, three stages are involved: (i) finding the best processing sequence, assuming that the transportation device is always available; (ii) generating a feasible schedule, taking into account the shared transportation resource; (iii) improving the schedule through a neighborhood search procedure. Relaxed and constrained versions of the full-space MILP are involved in stages (i) and (iii) with the simulation model taking care of stage (ii). Several examples are solved to illustrate the capabilities of the proposed method with the results showing better performance when compared to other published approaches. The balance between solution quality and total computational effort can easily be shifted by changing the number of lots rescheduled per iteration. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24523885

New continuous-time scheduling formulation for continuous plants under variable electricity cost / Pedro M. Castro 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. 6701–6714 Titre : New continuous-time scheduling formulation for continuous plants under variable electricity cost Type de document : texte imprimé Auteurs : Pedro M. Castro, Auteur ; Iiro Harjunkoski, Auteur ; Ignacio E. Grossmann, Auteur Année de publication : 2009 Article en page(s) : pp. 6701–6714 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Continuous  plants  Scheduling  Time-dependent  electricity  pricing  Discrete-time  formulation  Continuous-time  formulation Résumé : This work addresses the scheduling of continuous plants subject to energy constraints related to time-dependent electricity pricing and availability. Discrete- and continuous-time formulations are presented that can address these issues together with multiple intermediate due dates. Both formulations rely on the resource−task network process representation. Their computational performance is compared for the objective of total electricity minimization with the results favoring the discrete-time model due to the more natural way of handling such a wide variety of discrete events. In particular, it can successfully handle problems of industrial size. Nevertheless, the new continuous-time model is a major breakthrough since it is the first model of its type that is able to effectively incorporate time-variable utility profiles. When compared to a simple manual scheduling procedure, the proposed scheduling approaches can lead to potential electricity savings around 20% by switching production from periods of high to low electricity cost. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900073k [article] New continuous-time scheduling formulation for continuous plants under variable electricity cost [texte imprimé] / Pedro M. Castro, Auteur ; Iiro Harjunkoski, Auteur ; Ignacio E. Grossmann, Auteur . - 2009 . - pp. 6701–6714. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6701–6714 Mots-clés : Continuous  plants  Scheduling  Time-dependent  electricity  pricing  Discrete-time  formulation  Continuous-time  formulation Résumé : This work addresses the scheduling of continuous plants subject to energy constraints related to time-dependent electricity pricing and availability. Discrete- and continuous-time formulations are presented that can address these issues together with multiple intermediate due dates. Both formulations rely on the resource−task network process representation. Their computational performance is compared for the objective of total electricity minimization with the results favoring the discrete-time model due to the more natural way of handling such a wide variety of discrete events. In particular, it can successfully handle problems of industrial size. Nevertheless, the new continuous-time model is a major breakthrough since it is the first model of its type that is able to effectively incorporate time-variable utility profiles. When compared to a simple manual scheduling procedure, the proposed scheduling approaches can lead to potential electricity savings around 20% by switching production from periods of high to low electricity cost. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900073k

Optimal Scheduling of Pipeline Systems with a Resource−Task Network Continuous-Time Formulation / Pedro M. Castro 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. 11491–11505 Titre : Optimal Scheduling of Pipeline Systems with a Resource−Task Network Continuous-Time Formulation Type de document : texte imprimé Auteurs : Pedro M. Castro, Auteur Année de publication : 2011 Article en page(s) : pp. 11491–11505 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Pipeline  systems Résumé : This work addresses the short-term scheduling problem involved in the pipeline transportation of refined petroleum products to distribution centers serving local markets. A new continuous-time formulation is proposed that can handle complex treelike systems involving multiple refineries and depots. The novelty concerns the modeling of the complex storage policy associated with the flow of multiple products inside the pipeline. This is accomplished through the use of real and accumulated volume resources for every product, coupled with filling, moving, and emptying tasks, under the scope of the resource−task network process representation. Computational studies are performed to compare the performance of the new approach to three models from the literature that rely on the concept of batches rather than events to model what is in reality a continuous system. The results show that the proposed approach is wider in scope with the typical drawback of being less efficient for structural subclasses of the general problem. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1010993 [article] Optimal Scheduling of Pipeline Systems with a Resource−Task Network Continuous-Time Formulation [texte imprimé] / Pedro M. Castro, Auteur . - 2011 . - pp. 11491–11505. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11491–11505 Mots-clés : Pipeline  systems Résumé : This work addresses the short-term scheduling problem involved in the pipeline transportation of refined petroleum products to distribution centers serving local markets. A new continuous-time formulation is proposed that can handle complex treelike systems involving multiple refineries and depots. The novelty concerns the modeling of the complex storage policy associated with the flow of multiple products inside the pipeline. This is accomplished through the use of real and accumulated volume resources for every product, coupled with filling, moving, and emptying tasks, under the scope of the resource−task network process representation. Computational studies are performed to compare the performance of the new approach to three models from the literature that rely on the concept of batches rather than events to model what is in reality a continuous system. The results show that the proposed approach is wider in scope with the typical drawback of being less efficient for structural subclasses of the general problem. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1010993

Optimal short-term scheduling of large-scale multistage batch plants / Pedro M. Castro in Industrial & engineering chemistry research, Vol. 48 N° 24 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 11002–11016 Titre : Optimal short-term scheduling of large-scale multistage batch plants Type de document : texte imprimé Auteurs : Pedro M. Castro, Auteur ; Iiro Harjunkoski, Auteur ; Ignacio E. Grossmann, Auteur Année de publication : 2010 Article en page(s) : pp. 11002–11016 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Optimal--Short-Term--Scheduling--Large-Scale--Multistage--Batch  Plants Résumé : This paper presents a new decomposition algorithm for the optimal scheduling of large-scale multiproduct plants containing a large number of orders. Rather than tackling highly complex, full-space problems that cannot be solved in reasonable time, the complete set of orders is scheduled sequentially by considering one, or a couple of them, at a time. As we proceed through the iterations, previously scheduled orders can be partly rescheduled to allow for some flexibility while keeping the combinatorial complexity at a manageable level. Once a complete schedule is obtained, the same concept is applied to improve the schedule locally. The user can choose to rely on either a unit-specific or a sequencing variable based continuous-time mixed-integer linear programming model. In addition, there are other parameters that affect how the decomposition is carried out, so the algorithm is highly versatile and adaptable to problems of varying sizes. The largest problem solved is a real-life, 50-order, 17-unit, 6-stage problem, for which a very good solution can be found in less than 1 min of computational time. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900734x [article] Optimal short-term scheduling of large-scale multistage batch plants [texte imprimé] / Pedro M. Castro, Auteur ; Iiro Harjunkoski, Auteur ; Ignacio E. Grossmann, Auteur . - 2010 . - pp. 11002–11016. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 11002–11016 Mots-clés : Optimal--Short-Term--Scheduling--Large-Scale--Multistage--Batch  Plants Résumé : This paper presents a new decomposition algorithm for the optimal scheduling of large-scale multiproduct plants containing a large number of orders. Rather than tackling highly complex, full-space problems that cannot be solved in reasonable time, the complete set of orders is scheduled sequentially by considering one, or a couple of them, at a time. As we proceed through the iterations, previously scheduled orders can be partly rescheduled to allow for some flexibility while keeping the combinatorial complexity at a manageable level. Once a complete schedule is obtained, the same concept is applied to improve the schedule locally. The user can choose to rely on either a unit-specific or a sequencing variable based continuous-time mixed-integer linear programming model. In addition, there are other parameters that affect how the decomposition is carried out, so the algorithm is highly versatile and adaptable to problems of varying sizes. The largest problem solved is a real-life, 50-order, 17-unit, 6-stage problem, for which a very good solution can be found in less than 1 min of computational time. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900734x

Optimal short-term scheduling of large-scale multistage batch plants / Pedro M. Castro in Industrial & engineering chemistry research, Vol. 48 N° 24 (Décembre 2009) 

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