Documents disponibles écrits par cet auteur

An extended formulation for the flexible short-term scheduling of multiproduct semicontinuous plants / Elisabet Capon-Garcia in Industrial & engineering chemistry research, Vol. 48 N°4 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2009–2019 Titre : An extended formulation for the flexible short-term scheduling of multiproduct semicontinuous plants Type de document : texte imprimé Auteurs : Elisabet Capon-Garcia, Auteur ; Sergio Ferrer-Nadal, Auteur ; Moisès Graells, Auteur Année de publication : 2009 Article en page(s) : p. 2009–2019 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Semicontinuous  plants  Flexible  environments Résumé : Chemical plants are moving toward more-flexible environments, to adapt faster to market changes. For the sake of this flexibility, batch and continuous units might be integrated and operated along the same processing route in a semicontinuous mode, featured by production campaigns of finite duration. Constant production rates for the entire operation have been usually considered. Thus, production adjustments were achieved through storage resources, production line stops, and multiple product campaigns. The objective of this work is to improve the production schedules by developing a new concept for flexible manufacturing, which allows one to program production rate profiles within each semicontinuous operation campaign. Hence, the extended formulation presented allows to address the tradeoff between the opportunities that may arise when adjusting processing rates and the storage needs and opportunities. Finally, several case studies show that the proposed adjustment of the processing rates leads to less storage utilization and more-efficient production performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800539f [article] An extended formulation for the flexible short-term scheduling of multiproduct semicontinuous plants [texte imprimé] / Elisabet Capon-Garcia, Auteur ; Sergio Ferrer-Nadal, Auteur ; Moisès Graells, Auteur . - 2009 . - p. 2009–2019. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°4 (Février 2009) . - p. 2009–2019 Mots-clés : Semicontinuous  plants  Flexible  environments Résumé : Chemical plants are moving toward more-flexible environments, to adapt faster to market changes. For the sake of this flexibility, batch and continuous units might be integrated and operated along the same processing route in a semicontinuous mode, featured by production campaigns of finite duration. Constant production rates for the entire operation have been usually considered. Thus, production adjustments were achieved through storage resources, production line stops, and multiple product campaigns. The objective of this work is to improve the production schedules by developing a new concept for flexible manufacturing, which allows one to program production rate profiles within each semicontinuous operation campaign. Hence, the extended formulation presented allows to address the tradeoff between the opportunities that may arise when adjusting processing rates and the storage needs and opportunities. Finally, several case studies show that the proposed adjustment of the processing rates leads to less storage utilization and more-efficient production performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800539f

Costs for rescheduling actions / Kopanos, Georgios M. ; Elisabet Capon-Garcia ; Antonio Espuna ; Puigjaner, Luis in Industrial & engineering chemistry research, Vol. 47 n°22 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°22 (Novembre 2008) . - p. 8785–8795 Titre : Costs for rescheduling actions : a critical issue for reducing the gap between scheduling theory and practice Type de document : texte imprimé Auteurs : Kopanos, Georgios M., Auteur ; Elisabet Capon-Garcia, Auteur ; Antonio Espuna, Auteur ; Puigjaner, Luis, Auteur Année de publication : 2008 Article en page(s) : p. 8785–8795 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Scheduling Résumé : Rescheduling programmed tasks, when an unexpected event occurs, may affect the smooth operation of the plant if the initial schedule is not taken into account. This work addresses the penalty incurred by rescheduling actions and the optimization procedure to preserve schedule stability. To adjust the rescheduling process to the needs of the decision-maker, rescheduling costs are included to the initial objective function. Namely, unit reallocation and sequencing alterations are the sources of rescheduling costs. A mixed-integer linear programming (MILP) model for the simultaneous rescheduling of multiple operations that permits local reordering, unit reallocation, and accommodation of new orders, is considered. The need to consider rescheduling penalties in the optimization procedure is highlighted through several case studies. As a result, the production plant stability and efficiency are preserved, whereas the generation of pseudo-optimal schedules is avoided. In addition, the tradeoff between the original objective function optimization and the smooth operation of the plant is thoroughly examined. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8005676 [article] Costs for rescheduling actions : a critical issue for reducing the gap between scheduling theory and practice [texte imprimé] / Kopanos, Georgios M., Auteur ; Elisabet Capon-Garcia, Auteur ; Antonio Espuna, Auteur ; Puigjaner, Luis, Auteur . - 2008 . - p. 8785–8795. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°22 (Novembre 2008) . - p. 8785–8795 Mots-clés : Scheduling Résumé : Rescheduling programmed tasks, when an unexpected event occurs, may affect the smooth operation of the plant if the initial schedule is not taken into account. This work addresses the penalty incurred by rescheduling actions and the optimization procedure to preserve schedule stability. To adjust the rescheduling process to the needs of the decision-maker, rescheduling costs are included to the initial objective function. Namely, unit reallocation and sequencing alterations are the sources of rescheduling costs. A mixed-integer linear programming (MILP) model for the simultaneous rescheduling of multiple operations that permits local reordering, unit reallocation, and accommodation of new orders, is considered. The need to consider rescheduling penalties in the optimization procedure is highlighted through several case studies. As a result, the production plant stability and efficiency are preserved, whereas the generation of pseudo-optimal schedules is avoided. In addition, the tradeoff between the original objective function optimization and the smooth operation of the plant is thoroughly examined. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8005676

Improved short-term batch scheduling flexibility using variable recipes / Elisabet Capon-Garcia 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. 4983-4992 Titre : Improved short-term batch scheduling flexibility using variable recipes Type de document : texte imprimé Auteurs : Elisabet Capon-Garcia, Auteur ; Marta Moreno - Benito, Auteur ; Antonio Espuna, Auteur Année de publication : 2011 Article en page(s) : pp. 4983-4992 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Flexibility  Scheduling  Batchwise  Short  term Résumé : Batch scheduling and control decision levels are usually optimized separately, even though integrated decisions would potentially increase the overall performance of the plant. This work aims at including in the scheduling problem the operating conditions related to the control function, which are traditionally optimized and fixed beforehand, to shed light to the benefits that may be obtained when using variable recipes in contrast to fixed nominal recipes. A multiproduct and a multipurpose plant illustrate the proposed approach. In both cases, the potential benefits are confirmed resuting in clear advantages regarding overall economic benefit, when the variable recipes are introduced. Thus, the presented approach gives rise to new tradeoffs, since it allows new improvement opportunities associated with quality, safety, or changing operating policies, which are usually considered separately. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24128628 [article] Improved short-term batch scheduling flexibility using variable recipes [texte imprimé] / Elisabet Capon-Garcia, Auteur ; Marta Moreno - Benito, Auteur ; Antonio Espuna, Auteur . - 2011 . - pp. 4983-4992. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 9 (Mai 2011) . - pp. 4983-4992 Mots-clés : Flexibility  Scheduling  Batchwise  Short  term Résumé : Batch scheduling and control decision levels are usually optimized separately, even though integrated decisions would potentially increase the overall performance of the plant. This work aims at including in the scheduling problem the operating conditions related to the control function, which are traditionally optimized and fixed beforehand, to shed light to the benefits that may be obtained when using variable recipes in contrast to fixed nominal recipes. A multiproduct and a multipurpose plant illustrate the proposed approach. In both cases, the potential benefits are confirmed resuting in clear advantages regarding overall economic benefit, when the variable recipes are introduced. Thus, the presented approach gives rise to new tradeoffs, since it allows new improvement opportunities associated with quality, safety, or changing operating policies, which are usually considered separately. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24128628

Material Transfer Operations in Batch Scheduling / Sergio Ferrer-Nadal in Industrial & engineering chemistry research, Vol. 47 N°20 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7721-7732 Titre : Material Transfer Operations in Batch Scheduling : a critical modeling issue Type de document : texte imprimé Auteurs : Sergio Ferrer-Nadal, Auteur ; Elisabet Capon-Garcia, Auteur ; Carlos A. Méndez, Auteur ; Puigjaner, Luis, Auteur Année de publication : 2008 Article en page(s) : P. 7721-7732 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Batch  Scheduling  mixed-integer  linear  programming  (MILP) Résumé : An effective short-term scheduling formulation must simultaneously deal with several problem difficulties commonly arising in batch processes operations. One of the key features to be considered is the representation of the material transfer operations between process stages. A nonzero time as well as certain conditions and resources are always required to move the material from one processing stage to the next one according to the specified product recipe. The transfer task consumes a period of time during which a proper synchronization of the equipment units supplying and receiving the material is enforced. Synchronization implies that during the execution of the transfer task, one unit will be supplying the material whereas the other one will be receiving it and consequently, no other task can be simultaneously performed in both units. Most of the existing mixed-integer linear programming (MILP) optimization approaches have traditionally dealt with the batch scheduling problem assuming zero transfer times, and consequently no synchronization, between consecutive processing stages. Simplification relying on negligible transfer times may work properly for the scheduling of multiproduct batch plants with similar product recipes; however, it is demonstrated in this work that ignoring the important role of transfer times may seriously compromise the feasibility of the scheduling whenever shared units and storage tanks, material recycles, or bidirectional flows of products are to be considered. To overcome the serious limitations of current MILP-based scheduling approaches, a general precedence-based framework accounting for nonzero transfer times is introduced. Also, two alternative methods that avoid generating unfeasible schedules are proposed and tested in different case studies. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800075u [article] Material Transfer Operations in Batch Scheduling : a critical modeling issue [texte imprimé] / Sergio Ferrer-Nadal, Auteur ; Elisabet Capon-Garcia, Auteur ; Carlos A. Méndez, Auteur ; Puigjaner, Luis, Auteur . - 2008 . - P. 7721-7732. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7721-7732 Mots-clés : Batch  Scheduling  mixed-integer  linear  programming  (MILP) Résumé : An effective short-term scheduling formulation must simultaneously deal with several problem difficulties commonly arising in batch processes operations. One of the key features to be considered is the representation of the material transfer operations between process stages. A nonzero time as well as certain conditions and resources are always required to move the material from one processing stage to the next one according to the specified product recipe. The transfer task consumes a period of time during which a proper synchronization of the equipment units supplying and receiving the material is enforced. Synchronization implies that during the execution of the transfer task, one unit will be supplying the material whereas the other one will be receiving it and consequently, no other task can be simultaneously performed in both units. Most of the existing mixed-integer linear programming (MILP) optimization approaches have traditionally dealt with the batch scheduling problem assuming zero transfer times, and consequently no synchronization, between consecutive processing stages. Simplification relying on negligible transfer times may work properly for the scheduling of multiproduct batch plants with similar product recipes; however, it is demonstrated in this work that ignoring the important role of transfer times may seriously compromise the feasibility of the scheduling whenever shared units and storage tanks, material recycles, or bidirectional flows of products are to be considered. To overcome the serious limitations of current MILP-based scheduling approaches, a general precedence-based framework accounting for nonzero transfer times is introduced. Also, two alternative methods that avoid generating unfeasible schedules are proposed and tested in different case studies. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800075u