Documents disponibles écrits par cet auteur

Computational comparison of piecewise-linear relaxations for pooling problems / Chrysanthos E. Gounaris in Industrial & engineering chemistry research, Vol. 48 N° 12 (Juin 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5742–5766 Titre : Computational comparison of piecewise-linear relaxations for pooling problems Type de document : texte imprimé Auteurs : Chrysanthos E. Gounaris, Auteur ; Ruth Misener, Auteur ; Christodoulos A. Floudas, Auteur Année de publication : 2009 Article en page(s) : pp. 5742–5766 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pooling  problem  Relaxation  tightness  Global  optimization  algorithm  Piecewise  linearization  scheme Résumé : This work discusses alternative relaxation schemes for the pooling problem, a theoretically and practically interesting optimization problem. The problem nonconvexities appear in the form of bilinear terms and can be addressed with the relaxation technique based on the bilinear convex and concave envelopes. We explore ways to improve the relaxation tightness, and thus the efficiency of a global optimization algorithm, by employing a piecewise linearization scheme that partitions the original domain of the variables involved and applies the principles of bilinear relaxation for each one of the resulting subdomains. We employ 15 different piecewise relaxation schemes with mixed-integer representations and conduct a comprehensive computational comparison study over a collection of benchmark pooling problems. For each case, various partitioning variants can be envisioned, cumulatively accounting for a total of 56 700 relaxations. The results demonstrate that some of the schemes are clearly superior to their counterparts and should, therefore, be preferred in the optimization of pooling processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016048 [article] Computational comparison of piecewise-linear relaxations for pooling problems [texte imprimé] / Chrysanthos E. Gounaris, Auteur ; Ruth Misener, Auteur ; Christodoulos A. Floudas, Auteur . - 2009 . - pp. 5742–5766. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5742–5766 Mots-clés : Pooling  problem  Relaxation  tightness  Global  optimization  algorithm  Piecewise  linearization  scheme Résumé : This work discusses alternative relaxation schemes for the pooling problem, a theoretically and practically interesting optimization problem. The problem nonconvexities appear in the form of bilinear terms and can be addressed with the relaxation technique based on the bilinear convex and concave envelopes. We explore ways to improve the relaxation tightness, and thus the efficiency of a global optimization algorithm, by employing a piecewise linearization scheme that partitions the original domain of the variables involved and applies the principles of bilinear relaxation for each one of the resulting subdomains. We employ 15 different piecewise relaxation schemes with mixed-integer representations and conduct a comprehensive computational comparison study over a collection of benchmark pooling problems. For each case, various partitioning variants can be envisioned, cumulatively accounting for a total of 56 700 relaxations. The results demonstrate that some of the schemes are clearly superior to their counterparts and should, therefore, be preferred in the optimization of pooling processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016048

Global optimization of gas lifting operations / Ruth Misener in Industrial & engineering chemistry research, Vol. 48 N° 13 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6098–6104 Titre : Global optimization of gas lifting operations : a comparative study of piecewise linear formulations Type de document : texte imprimé Auteurs : Ruth Misener, Auteur ; Chrysanthos E. Gounaris, Auteur ; Christodoulos A. Floudas, Auteur Année de publication : 2009 Article en page(s) : pp. 6098–6104 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Gas  lifting  Piecewise  linearization  techniques  Oil  field  Scheduling Résumé : Continuous gas lifting is the process of increasing oil well production by injecting compressed natural gas, called “lift gas”, into the production tubing of an oil well [ Presented at the SPE Gas Technology Symposium, Calgary, Alberta, Canada, 1996]. This paper considers the problem of optimizing the distribution of a limited supply of lift gas to wells in an oil field using piecewise linearization techniques. Four modeling approaches, proposed by Nemhauser and Woolsey [ Integer and Combinatorial Optimization; J. Wiley: New York, 1988], Foudas [ Nonlinear and Mixed-Integer Optimization: Fundamentals and Applications; Oxford University Press: New York, 1995], Sherali [ Oper. Res. Lett. 2001, 28, 155.], and Keha et al. [ Oper. Res. Lett. 2004, 32, 44.], are presented and the gas lifting problem is solved using each method. Each of the four frameworks is sufficient to solve the problem to global optimality and the method presented by Keha et al. has the best computational performance. The gas lifting problem is used within the context of larger problems such as well scheduling in oil fields [ Comput. Chem. Eng. 2005, 29, 1523.], and this proposed work can be used to make one of the key parts of the well scheduling problem more efficient. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012117 [article] Global optimization of gas lifting operations : a comparative study of piecewise linear formulations [texte imprimé] / Ruth Misener, Auteur ; Chrysanthos E. Gounaris, Auteur ; Christodoulos A. Floudas, Auteur . - 2009 . - pp. 6098–6104. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6098–6104 Mots-clés : Gas  lifting  Piecewise  linearization  techniques  Oil  field  Scheduling Résumé : Continuous gas lifting is the process of increasing oil well production by injecting compressed natural gas, called “lift gas”, into the production tubing of an oil well [ Presented at the SPE Gas Technology Symposium, Calgary, Alberta, Canada, 1996]. This paper considers the problem of optimizing the distribution of a limited supply of lift gas to wells in an oil field using piecewise linearization techniques. Four modeling approaches, proposed by Nemhauser and Woolsey [ Integer and Combinatorial Optimization; J. Wiley: New York, 1988], Foudas [ Nonlinear and Mixed-Integer Optimization: Fundamentals and Applications; Oxford University Press: New York, 1995], Sherali [ Oper. Res. Lett. 2001, 28, 155.], and Keha et al. [ Oper. Res. Lett. 2004, 32, 44.], are presented and the gas lifting problem is solved using each method. Each of the four frameworks is sufficient to solve the problem to global optimality and the method presented by Keha et al. has the best computational performance. The gas lifting problem is used within the context of larger problems such as well scheduling in oil fields [ Comput. Chem. Eng. 2005, 29, 1523.], and this proposed work can be used to make one of the key parts of the well scheduling problem more efficient. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012117

Global optimization of large - scale eneralized pooling problems / Ruth Misener in Industrial & engineering chemistry research, Vol. 49 N° 11 (Juin 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 11 (Juin 2010) . - pp. 5424–5438 Titre : Global optimization of large - scale eneralized pooling problems : quadratically constrained MINLP models Type de document : texte imprimé Auteurs : Ruth Misener, Auteur ; Christodoulos A. Floudas, Auteur Année de publication : 2010 Article en page(s) : pp. 5424–5438 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Quadratically  constrained  MINLP Résumé : The generalized pooling problem is a generic way of identifying a topology containing sources nodes, intermediate storage tanks, and sinks when monitoring specific stream qualities is imperative. One important application domain of the generalized pooling problem is wastewater treatment. Choosing among the wide array of available wastewater treatment technologies is a combinatorially complex optimization problem that requires nonconvex terms to monitor regulated stream qualities about a treatment plant. In this work, we address five instantiations of the generalized pooling problem to global optimality by introducing (i) a quadratically constrained MINLP model formulation that reduces the number of bilinear terms, (ii) novel piecewise underestimation methods for the nonconvex bilinear terms to tighten the relaxation [Gounaris et al. Ind. Eng. Chem. Res. 2009, 48, 5742−5766; Wicaksono and Karimi AIChE J. 2008, 54, 991−1008], and (iii) a branch-and-bound algorithm suited to address the combinatorial complexity of the problem. Extensive computational results are presented for small, medium, large, and two very large-scale case studies which feature 48, 300, 675, and 1260 distinct bilinear terms, respectively. We show that the small, medium, and large case studies can be solved to global optimality efficiently. The two very large case studies can be solved within 0.9% and 2.3% of the global optimum, and when the additional assumption of a limited number of plants is introduced, they can be solved to global optimality. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100025e [article] Global optimization of large - scale eneralized pooling problems : quadratically constrained MINLP models [texte imprimé] / Ruth Misener, Auteur ; Christodoulos A. Floudas, Auteur . - 2010 . - pp. 5424–5438. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 11 (Juin 2010) . - pp. 5424–5438 Mots-clés : Quadratically  constrained  MINLP Résumé : The generalized pooling problem is a generic way of identifying a topology containing sources nodes, intermediate storage tanks, and sinks when monitoring specific stream qualities is imperative. One important application domain of the generalized pooling problem is wastewater treatment. Choosing among the wide array of available wastewater treatment technologies is a combinatorially complex optimization problem that requires nonconvex terms to monitor regulated stream qualities about a treatment plant. In this work, we address five instantiations of the generalized pooling problem to global optimality by introducing (i) a quadratically constrained MINLP model formulation that reduces the number of bilinear terms, (ii) novel piecewise underestimation methods for the nonconvex bilinear terms to tighten the relaxation [Gounaris et al. Ind. Eng. Chem. Res. 2009, 48, 5742−5766; Wicaksono and Karimi AIChE J. 2008, 54, 991−1008], and (iii) a branch-and-bound algorithm suited to address the combinatorial complexity of the problem. Extensive computational results are presented for small, medium, large, and two very large-scale case studies which feature 48, 300, 675, and 1260 distinct bilinear terms, respectively. We show that the small, medium, and large case studies can be solved to global optimality efficiently. The two very large case studies can be solved within 0.9% and 2.3% of the global optimum, and when the additional assumption of a limited number of plants is introduced, they can be solved to global optimality. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100025e