Documents disponibles écrits par cet auteur

Flexible aircraft fleeting and routing at TunisAir / Zeghal, F. M. in Journal of the operational research society (JORS), Vol. 62 N° 2 Special issue (Fevrier 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 2 Special issue (Fevrier 2011) . - pp. 368–380 Titre : Flexible aircraft fleeting and routing at TunisAir Type de document : texte imprimé Auteurs : Zeghal, F. M., Auteur ; Haouari, M., Auteur ; Sherali, H. D., Auteur Année de publication : 2011 Article en page(s) : pp. 368–380 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : OR  in  airlines  Airline  fleet  assignment  Aircraft  routing  Flexible  fleet  Flexible  flight  schedule  Column  generation Index. décimale : 001.424 Résumé : This paper addresses a Flexible Aircraft Fleeting and Routing Problem, which is motivated by the Tunisian national carrier TunisAir. A solution to this problem specifies the departure time of each flight, the subset of aircraft to be chartered or rented out, the individual aircraft assigned to each flight, as well as the sequence of flights to be flown by each aircraft. The objective is to maximize the expected total net profit, while satisfying activity constraints and long-term maintenance requirements. Tailored optimization-based heuristics are developed for solving this complex integrated problem. Computational experiments conducted on real data demonstrate that the proposed procedures are effective and robust, and significantly improve upon TunisAir's solutions. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n2/abs/jors2010100a.html [article] Flexible aircraft fleeting and routing at TunisAir [texte imprimé] / Zeghal, F. M., Auteur ; Haouari, M., Auteur ; Sherali, H. D., Auteur . - 2011 . - pp. 368–380. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 2 Special issue (Fevrier 2011) . - pp. 368–380 Mots-clés : OR  in  airlines  Airline  fleet  assignment  Aircraft  routing  Flexible  fleet  Flexible  flight  schedule  Column  generation Index. décimale : 001.424 Résumé : This paper addresses a Flexible Aircraft Fleeting and Routing Problem, which is motivated by the Tunisian national carrier TunisAir. A solution to this problem specifies the departure time of each flight, the subset of aircraft to be chartered or rented out, the individual aircraft assigned to each flight, as well as the sequence of flights to be flown by each aircraft. The objective is to maximize the expected total net profit, while satisfying activity constraints and long-term maintenance requirements. Tailored optimization-based heuristics are developed for solving this complex integrated problem. Computational experiments conducted on real data demonstrate that the proposed procedures are effective and robust, and significantly improve upon TunisAir's solutions. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n2/abs/jors2010100a.html

Minimizing the maximum network flow: models and algorithms with resource synergy considerations / B. J. Lunday in Journal of the operational research society (JORS), Vol. 63 N° 12 (Décembre 2012) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 63 N° 12 (Décembre 2012) . - pp. 1693–1707 Titre : Minimizing the maximum network flow: models and algorithms with resource synergy considerations Type de document : texte imprimé Auteurs : B. J. Lunday, Auteur ; Sherali, H. D., Auteur Année de publication : 2013 Article en page(s) : pp. 1693–1707 Note générale : operational research Langues : Anglais (eng) Mots-clés : network  interdiction;  synergy;  resource  allocation;  inner-linearization;  outer-approximation Index. décimale : 001.424 Résumé : In this paper, we model and solve the network interdiction problem of minimizing the maximum flow through a network from a given source node to a terminus node, while incorporating different forms of superadditive synergy effects of the resources applied to the arcs in the network. Within this context, we examine linear, concave, and convex–concave synergy relationships, illustrate their relative effect on optimal solution characteristics, and accordingly develop and test effective solution procedures for the underlying problems. For a concave synergy relationship, which yields a convex programme, we propose an inner-linearization procedure that significantly outperforms the competitive commercial solver SBB by improving the quality of solutions found by the latter by 6.2% (within a time limit of 1800 CPU s), while saving 84.5% of the required computational effort. For general non-concave synergy relationships, we develop an outer-approximation-based heuristic that achieves solutions of objective value 0.20% better than the commercial global optimization software BARON, with a 99.3% reduction in computational effort for the subset of test problems for which BARON could identify a feasible solution within the set time limit. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n12/abs/jors20128a.html [article] Minimizing the maximum network flow: models and algorithms with resource synergy considerations [texte imprimé] / B. J. Lunday, Auteur ; Sherali, H. D., Auteur . - 2013 . - pp. 1693–1707. operational research Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 63 N° 12 (Décembre 2012) . - pp. 1693–1707 Mots-clés : network  interdiction;  synergy;  resource  allocation;  inner-linearization;  outer-approximation Index. décimale : 001.424 Résumé : In this paper, we model and solve the network interdiction problem of minimizing the maximum flow through a network from a given source node to a terminus node, while incorporating different forms of superadditive synergy effects of the resources applied to the arcs in the network. Within this context, we examine linear, concave, and convex–concave synergy relationships, illustrate their relative effect on optimal solution characteristics, and accordingly develop and test effective solution procedures for the underlying problems. For a concave synergy relationship, which yields a convex programme, we propose an inner-linearization procedure that significantly outperforms the competitive commercial solver SBB by improving the quality of solutions found by the latter by 6.2% (within a time limit of 1800 CPU s), while saving 84.5% of the required computational effort. For general non-concave synergy relationships, we develop an outer-approximation-based heuristic that achieves solutions of objective value 0.20% better than the commercial global optimization software BARON, with a 99.3% reduction in computational effort for the subset of test problems for which BARON could identify a feasible solution within the set time limit. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n12/abs/jors20128a.html

A scenario generation-based lower bounding approach for stochastic scheduling problems / L. Liao in Journal of the operational research society (JORS), Vol. 63 N° 10 (Octobre 2012) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 63 N° 10 (Octobre 2012) . - pp. 1410–1420 Titre : A scenario generation-based lower bounding approach for stochastic scheduling problems Type de document : texte imprimé Auteurs : L. Liao, Auteur ; S. C. Sarin, Auteur ; Sherali, H. D., Auteur Année de publication : 2012 Article en page(s) : pp. 1410–1420 Langues : Anglais (eng) Mots-clés : scheduling;  stochastic  programming;  scenario  generation;  discrete  bounding;  total  weighted  tardiness Index. décimale : 001.424 Résumé : In this paper, we investigate scenario generation methods to establish lower bounds on the optimal objective value for stochastic scheduling problems that contain random parameters with continuous distributions. In contrast to the Sample Average Approximation (SAA) approach, which yields probabilistic bound values, we use an alternative bounding method that relies on the ideas of discrete bounding and recursive stratified sampling. Theoretical support is provided for deriving exact lower bounds for both expectation and conditional value-at-risk objectives. We illustrate the use of our method on the single machine total weighted tardiness problem. The results of our numerical investigation demonstrate good properties of our bounding method, compared with the SAA method and an earlier discrete bounding method. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n10/abs/jors2011150a.html [article] A scenario generation-based lower bounding approach for stochastic scheduling problems [texte imprimé] / L. Liao, Auteur ; S. C. Sarin, Auteur ; Sherali, H. D., Auteur . - 2012 . - pp. 1410–1420. Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 63 N° 10 (Octobre 2012) . - pp. 1410–1420 Mots-clés : scheduling;  stochastic  programming;  scenario  generation;  discrete  bounding;  total  weighted  tardiness Index. décimale : 001.424 Résumé : In this paper, we investigate scenario generation methods to establish lower bounds on the optimal objective value for stochastic scheduling problems that contain random parameters with continuous distributions. In contrast to the Sample Average Approximation (SAA) approach, which yields probabilistic bound values, we use an alternative bounding method that relies on the ideas of discrete bounding and recursive stratified sampling. Theoretical support is provided for deriving exact lower bounds for both expectation and conditional value-at-risk objectives. We illustrate the use of our method on the single machine total weighted tardiness problem. The results of our numerical investigation demonstrate good properties of our bounding method, compared with the SAA method and an earlier discrete bounding method. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n10/abs/jors2011150a.html

Set partitioning and packing versus assignment formulations for subassembly matching problems / A. Ghoniem in Journal of the operational research society (JORS), Vol. 62 N° 11 (Novembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 11 (Novembre 2011) . - pp. 2023–2033 Titre : Set partitioning and packing versus assignment formulations for subassembly matching problems Type de document : texte imprimé Auteurs : A. Ghoniem, Auteur ; Sherali, H. D., Auteur Année de publication : 2011 Article en page(s) : pp. 2023–2033 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Set  partitioning  Set  packing  Column  generation  Symmetry-defeating  constraints  Selective  assembly Index. décimale : 001.424 Résumé : This paper addresses alternative formulations and model enhancements for two combinatorial optimization problems that arise in subassembly matching problems. The first problem seeks to minimize the total deviation in certain quality characteristics for the resulting final products from a vector of target values, whereas the second aims at maximizing the throughput under specified tolerance restrictions. We propose set partitioning and packing models in concert with a specialized column generation (CG) procedure that significantly outperform alternative assignment-based formulations presented in the literature, even when the latter are enhanced via tailored symmetry-defeating strategies. In particular, we emphasize the critical importance of incorporating a complementary CG feature to consistently produce near-optimal solutions to the proposed set partitioning and packing models. Extensive computational results are presented to demonstrate the relative effectiveness of the different proposed modelling and algorithmic strategies. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n11/abs/jors2010165a.html [article] Set partitioning and packing versus assignment formulations for subassembly matching problems [texte imprimé] / A. Ghoniem, Auteur ; Sherali, H. D., Auteur . - 2011 . - pp. 2023–2033. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 11 (Novembre 2011) . - pp. 2023–2033 Mots-clés : Set  partitioning  Set  packing  Column  generation  Symmetry-defeating  constraints  Selective  assembly Index. décimale : 001.424 Résumé : This paper addresses alternative formulations and model enhancements for two combinatorial optimization problems that arise in subassembly matching problems. The first problem seeks to minimize the total deviation in certain quality characteristics for the resulting final products from a vector of target values, whereas the second aims at maximizing the throughput under specified tolerance restrictions. We propose set partitioning and packing models in concert with a specialized column generation (CG) procedure that significantly outperform alternative assignment-based formulations presented in the literature, even when the latter are enhanced via tailored symmetry-defeating strategies. In particular, we emphasize the critical importance of incorporating a complementary CG feature to consistently produce near-optimal solutions to the proposed set partitioning and packing models. Extensive computational results are presented to demonstrate the relative effectiveness of the different proposed modelling and algorithmic strategies. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n11/abs/jors2010165a.html