Documents disponibles écrits par cet auteur

Novel unified modeling approach for short-term scheduling / Munawar A. Shaik in Industrial & engineering chemistry research, Vol. 48 N° 6 (Mars 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2947–2964 Titre : Novel unified modeling approach for short-term scheduling Type de document : texte imprimé Auteurs : Munawar A. Shaik, Auteur ; Christodoulos A. Floudas, Auteur Année de publication : 2009 Article en page(s) : pp. 2947–2964 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Short-term  scheduling  Unit-specific  event-based  formulations  Three-index  binary  variables  Continuous  variables Résumé : Unit-specific event-based continuous time models have gained significant attention in the past decade for their advantages of requiring less number of event points, smaller problem size, and hence, a better computational performance. In the literature, different models had been proposed for short-term scheduling problems involving with and without resource constraints using unit-specific event-based formulations. For scheduling problems involving no resource constraints, generally the unit-specific event-based models do not allow tasks to continue over multiple events unlike in models that account for resource constraints explicitly. In this work, we emphasize the necessity for allowing tasks to take place over multiple event points even for simpler scheduling problems involving no resource constraints. We propose a novel short-term scheduling model using three-index binary and continuous variables that efficiently merges both the problems involving resources and no resource constraints into a unified, generic common framework. The proposed approach is based on state-task-network (STN) representation and is suitable for both batch and continuous plants, although we focus only on batch plants in this paper. Detailed computational case studies are presented to demonstrate the efficacy of the proposed model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010726 [article] Novel unified modeling approach for short-term scheduling [texte imprimé] / Munawar A. Shaik, Auteur ; Christodoulos A. Floudas, Auteur . - 2009 . - pp. 2947–2964. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2947–2964 Mots-clés : Short-term  scheduling  Unit-specific  event-based  formulations  Three-index  binary  variables  Continuous  variables Résumé : Unit-specific event-based continuous time models have gained significant attention in the past decade for their advantages of requiring less number of event points, smaller problem size, and hence, a better computational performance. In the literature, different models had been proposed for short-term scheduling problems involving with and without resource constraints using unit-specific event-based formulations. For scheduling problems involving no resource constraints, generally the unit-specific event-based models do not allow tasks to continue over multiple events unlike in models that account for resource constraints explicitly. In this work, we emphasize the necessity for allowing tasks to take place over multiple event points even for simpler scheduling problems involving no resource constraints. We propose a novel short-term scheduling model using three-index binary and continuous variables that efficiently merges both the problems involving resources and no resource constraints into a unified, generic common framework. The proposed approach is based on state-task-network (STN) representation and is suitable for both batch and continuous plants, although we focus only on batch plants in this paper. Detailed computational case studies are presented to demonstrate the efficacy of the proposed model. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010726

Short - term scheduling of refinery crude oil operations / Sanjeev Yadav in Industrial & engineering chemistry research, Vol. 51 N° 27 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 27 (Juillet 2012) . - pp. 9287–9299 Titre : Short - term scheduling of refinery crude oil operations Type de document : texte imprimé Auteurs : Sanjeev Yadav, Auteur ; Munawar A. Shaik, Auteur Année de publication : 2012 Article en page(s) : pp. 9287–9299 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Refinery  Oil  operations Résumé : Scheduling of crude oil unloading and loading operations is an important optimization problem for minimizing the significant costs at the front end of a refinery. The scheduling problem involves finding the optimal operation of crude-oil unloading from vessels, its transfer to storage tanks, and determination of charging schedule for each crude-oil mixture to the continuous distillation units. In this work, we propose a simplified state-task-network (STN) based formulation to address the problem of short-term scheduling of crude oil operations using unit-specific event-based continuous-time representation by incorporating explicit storage tasks for handling material transfer from storage and charging tanks. Constraints are developed for different cases corresponding to material flow in a tank based on (i) whether bypassing is allowed or not, (ii) whether crude mixing is allowed or not, and based on (iii) whether simultaneous input and output is allowed or not. The proposed model is applied to a few benchmark examples from literature giving better results with improved objective functions compared with the results reported in previous works. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300046g [article] Short - term scheduling of refinery crude oil operations [texte imprimé] / Sanjeev Yadav, Auteur ; Munawar A. Shaik, Auteur . - 2012 . - pp. 9287–9299. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 27 (Juillet 2012) . - pp. 9287–9299 Mots-clés : Refinery  Oil  operations Résumé : Scheduling of crude oil unloading and loading operations is an important optimization problem for minimizing the significant costs at the front end of a refinery. The scheduling problem involves finding the optimal operation of crude-oil unloading from vessels, its transfer to storage tanks, and determination of charging schedule for each crude-oil mixture to the continuous distillation units. In this work, we propose a simplified state-task-network (STN) based formulation to address the problem of short-term scheduling of crude oil operations using unit-specific event-based continuous-time representation by incorporating explicit storage tasks for handling material transfer from storage and charging tanks. Constraints are developed for different cases corresponding to material flow in a tank based on (i) whether bypassing is allowed or not, (ii) whether crude mixing is allowed or not, and based on (iii) whether simultaneous input and output is allowed or not. The proposed model is applied to a few benchmark examples from literature giving better results with improved objective functions compared with the results reported in previous works. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300046g