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Journal of the operational research society (JORS) |
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Ajouter le résultat dans votre panierMinimization of the k-th maximum and its application on LMS regression and VaR optimization / X. Huang in Journal of the operational research society (JORS), Vol. 63 N° 11 (Novembre 2012)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1479–1491
Titre : Minimization of the k-th maximum and its application on LMS regression and VaR optimization Type de document : texte imprimé Auteurs : X. Huang, Auteur ; J. Xu, Auteur ; Wang, S., Auteur Année de publication : 2012 Article en page(s) : pp. 1479–1491 Note générale : operational research Langues : Anglais (eng) Mots-clés : piecewise linear optimization; least median of squares; value-at-risk Index. décimale : 001.424 Résumé : Motivated by two important problems, the least median of squares (LMS) regression and value-at-risk (VaR) optimization, this paper considers the problem of minimizing the k-th maximum for linear functions. For this study, a sufficient and necessary condition of local optimality is given. From this condition and other properties, we propose an algorithm that uses linear programming technique. The algorithm is assessed on real data sets and the experiments for LMS regression and VaR optimization both show its effectiveness. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011163a.html [article] Minimization of the k-th maximum and its application on LMS regression and VaR optimization [texte imprimé] / X. Huang, Auteur ; J. Xu, Auteur ; Wang, S., Auteur . - 2012 . - pp. 1479–1491.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1479–1491
Mots-clés : piecewise linear optimization; least median of squares; value-at-risk Index. décimale : 001.424 Résumé : Motivated by two important problems, the least median of squares (LMS) regression and value-at-risk (VaR) optimization, this paper considers the problem of minimizing the k-th maximum for linear functions. For this study, a sufficient and necessary condition of local optimality is given. From this condition and other properties, we propose an algorithm that uses linear programming technique. The algorithm is assessed on real data sets and the experiments for LMS regression and VaR optimization both show its effectiveness. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011163a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1492–1498
Titre : Online simulation for a real-time route dispatching problem Type de document : texte imprimé Auteurs : L. Schmidt, Auteur ; P. Gazmuri, Auteur Année de publication : 2012 Article en page(s) : pp. 1492–1498 Note générale : operational research Langues : Anglais (eng) Mots-clés : routing; dispatching; online simulation Index. décimale : 001.424 Résumé : In this article we present an online simulation application for a decision problem that operates in real time, where products have to be dispatched from two depots to clients that are geographically distributed throughout the city. The system's behaviour is highly stochastic, due to the random behaviour of the client's demand (in time and space), and the random times of order preparation, travelling times of dispatchers (these are motorcycle drivers) and absence rate of drivers each day. A decision scheme is proposed that combines elements of vehicle routing with time windows, real-time dispatching of drivers and online simulation, through which information on future events is considered in the decision-making process. Two major conclusions are obtained when this scheme is applied to real data. First, we show that the proposed algorithm for order consolidation and route dispatching can be very advantageous from the point of view of logistics costs and quality of service. Second, we show that online simulation and, specifically, the Simulation-based Real-time Decision Making methodology (SRDM) can further improve the quality of the results. New ideas for further work are also proposed. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011151a.html [article] Online simulation for a real-time route dispatching problem [texte imprimé] / L. Schmidt, Auteur ; P. Gazmuri, Auteur . - 2012 . - pp. 1492–1498.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1492–1498
Mots-clés : routing; dispatching; online simulation Index. décimale : 001.424 Résumé : In this article we present an online simulation application for a decision problem that operates in real time, where products have to be dispatched from two depots to clients that are geographically distributed throughout the city. The system's behaviour is highly stochastic, due to the random behaviour of the client's demand (in time and space), and the random times of order preparation, travelling times of dispatchers (these are motorcycle drivers) and absence rate of drivers each day. A decision scheme is proposed that combines elements of vehicle routing with time windows, real-time dispatching of drivers and online simulation, through which information on future events is considered in the decision-making process. Two major conclusions are obtained when this scheme is applied to real data. First, we show that the proposed algorithm for order consolidation and route dispatching can be very advantageous from the point of view of logistics costs and quality of service. Second, we show that online simulation and, specifically, the Simulation-based Real-time Decision Making methodology (SRDM) can further improve the quality of the results. New ideas for further work are also proposed. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011151a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1499–1507
Titre : n (r, nQ) inventory model for packaged deteriorating products with compound poisson demand Type de document : texte imprimé Auteurs : S. M. H. Molana, Auteur ; H. Davoudpour, Auteur ; S. Minner, Auteur Année de publication : 2012 Article en page(s) : pp. 1499–1507 Note générale : operational research Langues : Anglais (eng) Mots-clés : inventory control; deteriorating items; continuous review (r, nQ) policy; compound Poisson demand Index. décimale : 001.424 Résumé : We consider a liquid type of a deteriorating item which is packaged by an outside supplier and is delivered to final customers by a distributor. Customers arrive according to a Poisson process and ask for an integer number of packages. Unsatisfied demands are backordered. The inventory is reviewed continuously and replenished from an external supplier with a positive deterministic lead time following an (r, nQ) policy. The product in each package deteriorates continuously over time during transportation and storage. Therefore, the distributor cannot deliver exactly one unit of usable material in each package. We develop a model to determine the optimal inventory control parameters and the required size of a package to minimize expected average costs and illustrate the benefit of this method compared to a sequential approach based on an example from practice. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011154a.html [article] n (r, nQ) inventory model for packaged deteriorating products with compound poisson demand [texte imprimé] / S. M. H. Molana, Auteur ; H. Davoudpour, Auteur ; S. Minner, Auteur . - 2012 . - pp. 1499–1507.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1499–1507
Mots-clés : inventory control; deteriorating items; continuous review (r, nQ) policy; compound Poisson demand Index. décimale : 001.424 Résumé : We consider a liquid type of a deteriorating item which is packaged by an outside supplier and is delivered to final customers by a distributor. Customers arrive according to a Poisson process and ask for an integer number of packages. Unsatisfied demands are backordered. The inventory is reviewed continuously and replenished from an external supplier with a positive deterministic lead time following an (r, nQ) policy. The product in each package deteriorates continuously over time during transportation and storage. Therefore, the distributor cannot deliver exactly one unit of usable material in each package. We develop a model to determine the optimal inventory control parameters and the required size of a package to minimize expected average costs and illustrate the benefit of this method compared to a sequential approach based on an example from practice. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011154a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1508–1515
Titre : Single-machine scheduling problems with past-sequence-dependent delivery times and position-dependent processing times Type de document : texte imprimé Auteurs : S.-J. Yang, Auteur ; D.-L. Yang, Auteur Année de publication : 2012 Article en page(s) : pp. 1508–1515 Note générale : operational research Langues : Anglais (eng) Mots-clés : scheduling; position-dependent processing times; past-sequence-dependent delivery times; due-window assignment; total absolute differences in completion times; total absolute differences in waiting times Index. décimale : 001.424 Résumé : This paper considers single-machine scheduling problems with job delivery times where the actual job processing time of a job is defined by a function dependent on its position in a schedule. We assume that the job delivery time is proportional to the job waiting time. We investigate the minimization problems of the sum of earliness, tardiness, and due-window-related cost, the total absolute differences in completion times, and the total absolute differences in waiting times on a single-machine setting. The polynomial time algorithms are proposed to optimally solve the above objective functions. We also investigate some special cases of the problem under study and show that they can be optimally solved by lower order algorithms. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011155a.html [article] Single-machine scheduling problems with past-sequence-dependent delivery times and position-dependent processing times [texte imprimé] / S.-J. Yang, Auteur ; D.-L. Yang, Auteur . - 2012 . - pp. 1508–1515.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1508–1515
Mots-clés : scheduling; position-dependent processing times; past-sequence-dependent delivery times; due-window assignment; total absolute differences in completion times; total absolute differences in waiting times Index. décimale : 001.424 Résumé : This paper considers single-machine scheduling problems with job delivery times where the actual job processing time of a job is defined by a function dependent on its position in a schedule. We assume that the job delivery time is proportional to the job waiting time. We investigate the minimization problems of the sum of earliness, tardiness, and due-window-related cost, the total absolute differences in completion times, and the total absolute differences in waiting times on a single-machine setting. The polynomial time algorithms are proposed to optimally solve the above objective functions. We also investigate some special cases of the problem under study and show that they can be optimally solved by lower order algorithms. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011155a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1516–1533
Titre : The efficiency of public and publicly subsidized high schools in Spain : evidence from PISA-2006 Type de document : texte imprimé Auteurs : M.-J. Mancebón, Auteur ; J. Calero, Auteur ; Á. Choi, Auteur Année de publication : 2012 Article en page(s) : pp. 1516–1533 Note générale : operational research Langues : Anglais (eng) Mots-clés : efficiency; educational finance; resource allocation; PISA Index. décimale : 001.424 Résumé : This paper compares the efficiency of Spanish public and publicly subsidized private high schools by data envelopment analysis (DEA), employing the results provided by a hierarchical linear model (HLM) applied to PISA-2006 (Programme for International Students Assessment) microdata. The study places special emphasis on the estimation of the determinants of school outcomes. The educational production function is estimated through an HLM that takes into account the nested nature of PISA data. Inefficiencies are then measured through DEA and decomposed into two types: managerial (related to individual performance), and programme (related to structural differences between management models), following the approach adopted by Silva Portela and Thanassoulis. Once differences in students’ backgrounds, school resources and individual management inefficiencies are removed, the results reveal that Spanish public high schools are more efficient than their publicly subsidized private equivalents. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011156a.html [article] The efficiency of public and publicly subsidized high schools in Spain : evidence from PISA-2006 [texte imprimé] / M.-J. Mancebón, Auteur ; J. Calero, Auteur ; Á. Choi, Auteur . - 2012 . - pp. 1516–1533.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1516–1533
Mots-clés : efficiency; educational finance; resource allocation; PISA Index. décimale : 001.424 Résumé : This paper compares the efficiency of Spanish public and publicly subsidized private high schools by data envelopment analysis (DEA), employing the results provided by a hierarchical linear model (HLM) applied to PISA-2006 (Programme for International Students Assessment) microdata. The study places special emphasis on the estimation of the determinants of school outcomes. The educational production function is estimated through an HLM that takes into account the nested nature of PISA data. Inefficiencies are then measured through DEA and decomposed into two types: managerial (related to individual performance), and programme (related to structural differences between management models), following the approach adopted by Silva Portela and Thanassoulis. Once differences in students’ backgrounds, school resources and individual management inefficiencies are removed, the results reveal that Spanish public high schools are more efficient than their publicly subsidized private equivalents. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011156a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1534–1544
Titre : A mathematical programming model for the fuzzy analytic network process : applications of international investment Type de document : texte imprimé Auteurs : J.-J. Huang, Auteur Année de publication : 2012 Article en page(s) : pp. 1534–1544 Note générale : operational research Langues : Anglais (eng) Mots-clés : multiple criteria analysis; analytic network process (ANP); fuzzy judgments; fuzzy analytic network process (FANP); international investment Index. décimale : 001.424 Résumé : Currently, the analytic network process (ANP) method is widely employed to consider the multiple criteria analysis problems with dependence and feedback effects. However, in order to extend the ANP to resolve the problem of uncertainty or human subjective judgment, the concepts of fuzzy numbers should be incorporated into the ANP to represent the subjective uncertain pairwise judgments. In this paper, therefore, we propose a novel fuzzy analytic network process (FANP) model by solving a mathematical programming problem. Unlike other FANPs, the proposed method does not require the reciprocity assumption of the weight ratios between criteria, and it can derive local and global weights simultaneously in a single model. Two numerical examples of international investment problems are used to demonstrate the proposed method. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011164a.html [article] A mathematical programming model for the fuzzy analytic network process : applications of international investment [texte imprimé] / J.-J. Huang, Auteur . - 2012 . - pp. 1534–1544.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1534–1544
Mots-clés : multiple criteria analysis; analytic network process (ANP); fuzzy judgments; fuzzy analytic network process (FANP); international investment Index. décimale : 001.424 Résumé : Currently, the analytic network process (ANP) method is widely employed to consider the multiple criteria analysis problems with dependence and feedback effects. However, in order to extend the ANP to resolve the problem of uncertainty or human subjective judgment, the concepts of fuzzy numbers should be incorporated into the ANP to represent the subjective uncertain pairwise judgments. In this paper, therefore, we propose a novel fuzzy analytic network process (FANP) model by solving a mathematical programming problem. Unlike other FANPs, the proposed method does not require the reciprocity assumption of the weight ratios between criteria, and it can derive local and global weights simultaneously in a single model. Two numerical examples of international investment problems are used to demonstrate the proposed method. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011164a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1545–1555
Titre : Parallel systems under two sequential attacks with imperfect detection of the first attack outcome Type de document : texte imprimé Auteurs : G. Levitin, Auteur ; K. Hausken, Auteur Année de publication : 2012 Article en page(s) : pp. 1545–1555 Note générale : operational research Langues : Anglais (eng) Mots-clés : attack; defence; parallel system; identification error; survivability; minmax Index. décimale : 001.424 Résumé : The paper compares the efficiency of single and double attack against a system consisting of identical parallel elements. An attacker maximizes the system vulnerability (probability of total destruction). In order to destroy the system, the attacker distributes its constrained resource optimally across two attacks and chooses the number of elements to be attacked in the first attack. The attacker observes which elements are destroyed and not destroyed in the first attack and allocates its remaining resource into attacking the remaining elements in the second attack. The paper considers two types of identification errors: wrong identification of a destroyed element as not destroyed, and wrong identification of a not destroyed element as destroyed. First, the influence of the identification error probabilities on the optimal attack strategy against a system with a fixed number of elements is analysed. Thereafter, a minmax two-period game between the attacker and the defender is considered, in which the defender in the first period distributes its constrained resource between deploying redundant elements and protecting them against the attack in the second period. It is shown how the identification error probabilities affect the defence strategy. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors20124a.html [article] Parallel systems under two sequential attacks with imperfect detection of the first attack outcome [texte imprimé] / G. Levitin, Auteur ; K. Hausken, Auteur . - 2012 . - pp. 1545–1555.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1545–1555
Mots-clés : attack; defence; parallel system; identification error; survivability; minmax Index. décimale : 001.424 Résumé : The paper compares the efficiency of single and double attack against a system consisting of identical parallel elements. An attacker maximizes the system vulnerability (probability of total destruction). In order to destroy the system, the attacker distributes its constrained resource optimally across two attacks and chooses the number of elements to be attacked in the first attack. The attacker observes which elements are destroyed and not destroyed in the first attack and allocates its remaining resource into attacking the remaining elements in the second attack. The paper considers two types of identification errors: wrong identification of a destroyed element as not destroyed, and wrong identification of a not destroyed element as destroyed. First, the influence of the identification error probabilities on the optimal attack strategy against a system with a fixed number of elements is analysed. Thereafter, a minmax two-period game between the attacker and the defender is considered, in which the defender in the first period distributes its constrained resource between deploying redundant elements and protecting them against the attack in the second period. It is shown how the identification error probabilities affect the defence strategy. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors20124a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1556–1565
Titre : Predicting ambulance demand using singular spectrum analysis Type de document : texte imprimé Auteurs : J. L. Vile, Auteur ; J. W. Gillard, Auteur ; P. R. Harper, Auteur Année de publication : 2012 Article en page(s) : pp. 1556–1565 Note générale : operational research Langues : Anglais (eng) Mots-clés : health service; emergency medical services; forecasting; singular spectrum analysis Index. décimale : 001.424 Résumé : This paper demonstrates techniques to generate accurate predictions of demand exerted upon the Emergency Medical Services (EMS) using data provided by the Welsh Ambulance Service Trust (WAST). The aim is to explore new methods to produce accurate forecasts that can be subsequently embedded into current OR methodologies to optimise resource allocation of vehicles and staff, and allow rapid response to potentially life-threatening emergencies. Our analysis explores a relatively new non-parametric technique for time series analysis known as Singular Spectrum Analysis (SSA). We explain the theory of SSA and evaluate the performance of this approach by comparing the results with those produced by conventional time series methods. We show that in addition to being more flexible in approach, SSA produces superior longer-term forecasts (which are especially helpful for EMS planning), and comparable shorter-term forecasts to well established methods. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011160a.html [article] Predicting ambulance demand using singular spectrum analysis [texte imprimé] / J. L. Vile, Auteur ; J. W. Gillard, Auteur ; P. R. Harper, Auteur . - 2012 . - pp. 1556–1565.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1556–1565
Mots-clés : health service; emergency medical services; forecasting; singular spectrum analysis Index. décimale : 001.424 Résumé : This paper demonstrates techniques to generate accurate predictions of demand exerted upon the Emergency Medical Services (EMS) using data provided by the Welsh Ambulance Service Trust (WAST). The aim is to explore new methods to produce accurate forecasts that can be subsequently embedded into current OR methodologies to optimise resource allocation of vehicles and staff, and allow rapid response to potentially life-threatening emergencies. Our analysis explores a relatively new non-parametric technique for time series analysis known as Singular Spectrum Analysis (SSA). We explain the theory of SSA and evaluate the performance of this approach by comparing the results with those produced by conventional time series methods. We show that in addition to being more flexible in approach, SSA produces superior longer-term forecasts (which are especially helpful for EMS planning), and comparable shorter-term forecasts to well established methods. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011160a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1566–1577
Titre : Optimized material requirements planning for semiconductor manufacturing Type de document : texte imprimé Auteurs : R. J. Milne, Auteur ; C.-T. Wan, Auteur ; C.-K. A. Yen, Auteur Année de publication : 2012 Article en page(s) : pp. 1566–1577 Note générale : opertaional research Langues : Anglais (eng) Mots-clés : practice of OR; production; material requirements planning (MRP); heuristics; linear programming Index. décimale : 001.424 Résumé : This paper describes a custom operational research algorithm, which is run nightly by IBM to create a material requirements plan for its semiconductor fabrication facility in Vermont, USA. To model alternative manufacturing processes and part substitutions, this application interweaves linear programming and heuristic methods to reap the benefits of each decision technology. At each level of the bills of materials supply chain with complex decision choices to be made, parallel linear programmes are invoked and their results are fed into a material requirements planning (MRP) heuristic, which processes parts through multiple iterations. The results from processing one level of the bills of materials supply chain are exploded to create demand for the next level and the interweaving of the two decision technologies continues. The algorithm creates recommended manufacturing releases and work-in-process priorities. These outputs point out opportunities for improvement in order to satisfy all demands on time. The output can be interpreted with well-known MRP assumptions. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors20121a.html [article] Optimized material requirements planning for semiconductor manufacturing [texte imprimé] / R. J. Milne, Auteur ; C.-T. Wan, Auteur ; C.-K. A. Yen, Auteur . - 2012 . - pp. 1566–1577.
opertaional research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1566–1577
Mots-clés : practice of OR; production; material requirements planning (MRP); heuristics; linear programming Index. décimale : 001.424 Résumé : This paper describes a custom operational research algorithm, which is run nightly by IBM to create a material requirements plan for its semiconductor fabrication facility in Vermont, USA. To model alternative manufacturing processes and part substitutions, this application interweaves linear programming and heuristic methods to reap the benefits of each decision technology. At each level of the bills of materials supply chain with complex decision choices to be made, parallel linear programmes are invoked and their results are fed into a material requirements planning (MRP) heuristic, which processes parts through multiple iterations. The results from processing one level of the bills of materials supply chain are exploded to create demand for the next level and the interweaving of the two decision technologies continues. The algorithm creates recommended manufacturing releases and work-in-process priorities. These outputs point out opportunities for improvement in order to satisfy all demands on time. The output can be interpreted with well-known MRP assumptions. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors20121a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1578–1588
Titre : Stochastic analysis of ordered median problems Type de document : texte imprimé Auteurs : Z. Drezner, Auteur ; S. Nickel, Auteur ; H.-P. Ziegler, Auteur Année de publication : 2012 Article en page(s) : pp. 1578–1588 Note générale : operational research Langues : Anglais (eng) Mots-clés : location; stochastic models; ordered median; order statistics Index. décimale : 001.424 Résumé : Many location problems can be expressed as ordered median objective. In this paper, we investigate the ordered median objective when the demand points are generated in a circle. We find the mean and variance of the kth distance from the centre of the circle and the correlation matrix between all pairs of ordered distances. By applying these values, we calculate the mean and variance of any ordered median objective and the correlation coefficient between two ordered median objectives. The usefulness of the results is demonstrated by calculating various probabilities such as: What is the probability that the mean distance is greater than the truncated mean distance? What is the probability that the maximum distance is greater than 0.9? What is the probability that the range of distances is greater than 0.8? An analysis of an illustrative example also demonstrates the usefulness of the analysis. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors20122a.html [article] Stochastic analysis of ordered median problems [texte imprimé] / Z. Drezner, Auteur ; S. Nickel, Auteur ; H.-P. Ziegler, Auteur . - 2012 . - pp. 1578–1588.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1578–1588
Mots-clés : location; stochastic models; ordered median; order statistics Index. décimale : 001.424 Résumé : Many location problems can be expressed as ordered median objective. In this paper, we investigate the ordered median objective when the demand points are generated in a circle. We find the mean and variance of the kth distance from the centre of the circle and the correlation matrix between all pairs of ordered distances. By applying these values, we calculate the mean and variance of any ordered median objective and the correlation coefficient between two ordered median objectives. The usefulness of the results is demonstrated by calculating various probabilities such as: What is the probability that the mean distance is greater than the truncated mean distance? What is the probability that the maximum distance is greater than 0.9? What is the probability that the range of distances is greater than 0.8? An analysis of an illustrative example also demonstrates the usefulness of the analysis. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors20122a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1589–1599
Titre : Scheduling healthcare services in a home healthcare system Type de document : texte imprimé Auteurs : Y.-J. An, Auteur ; Y.-D. Kim, Auteur ; B. J. Jeong, Auteur Année de publication : 2012 Article en page(s) : pp. 1589–1599 Note générale : operational research Langues : Anglais (eng) Mots-clés : home healthcare management; scheduling; heuristic Index. décimale : 001.424 Résumé : We consider a scheduling problem in a home healthcare system in which nurses visit patients regularly for relatively minor healthcare services. Intervals between the visits may differ for different patients. On each day in the planning horizon, a nurse must visit the patients assigned to her/him on that day, and then return to the hospital. For the problem of determining the visiting schedule with the objective of minimizing total travel time of the nurse over the planning horizon, we develop a two-phase heuristic algorithm. To evaluate performance of the proposed algorithm, a series of computational tests is performed on a number of randomly generated problem instances and a real instance. Results of the tests show that the heuristic algorithm gives near optimal solutions for problems of practical sizes in a reasonable time. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011153a.html [article] Scheduling healthcare services in a home healthcare system [texte imprimé] / Y.-J. An, Auteur ; Y.-D. Kim, Auteur ; B. J. Jeong, Auteur . - 2012 . - pp. 1589–1599.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1589–1599
Mots-clés : home healthcare management; scheduling; heuristic Index. décimale : 001.424 Résumé : We consider a scheduling problem in a home healthcare system in which nurses visit patients regularly for relatively minor healthcare services. Intervals between the visits may differ for different patients. On each day in the planning horizon, a nurse must visit the patients assigned to her/him on that day, and then return to the hospital. For the problem of determining the visiting schedule with the objective of minimizing total travel time of the nurse over the planning horizon, we develop a two-phase heuristic algorithm. To evaluate performance of the proposed algorithm, a series of computational tests is performed on a number of randomly generated problem instances and a real instance. Results of the tests show that the heuristic algorithm gives near optimal solutions for problems of practical sizes in a reasonable time. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011153a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1600–1612
Titre : FuelOpt : a decision support system for forest fuel logistics Type de document : texte imprimé Auteurs : P. Flisberg, Auteur ; M. Frisk, Auteur ; M. Rönnqvist, Auteur Année de publication : 2012 Article en page(s) : pp. 1600–1612 Note générale : operational research Langues : Anglais (eng) Mots-clés : practice of OR; transport; energy; inventory; linear programming Index. décimale : 001.424 Résumé : The use of forest fuel is increasing at heating plants in Sweden. Heating plants provide energy in the form of hot water for heating houses and apartments in local municipalities. Forest fuel are products obtained from harvesting in forests that cannot be used for further processing at sawmills and pulp and paper mills. Examples of such products are tree branches, tree tops and low quality logs. The optimization of the supply chain for round-wood (logs to sawmills, pulp and paper mills) and for forest fuel is similar but involves two main differences. First, forest fuel has to be converted into chips before delivery to the customer, and second, the demand for forest fuel varies over the year due to the temperature. To balance the chipping and transportation capacities over time, it is important to manage inventory levels at terminals. The optimization model developed provides decision support for questions regarding the choice of technology for chipping, where to perform the chipping operations, and the allocation of different assortments to heating plants. The system has been tested on a large case study from a Swedish forest energy company. The results show large savings and that the system is very useful for both planning and business development. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011157a.html [article] FuelOpt : a decision support system for forest fuel logistics [texte imprimé] / P. Flisberg, Auteur ; M. Frisk, Auteur ; M. Rönnqvist, Auteur . - 2012 . - pp. 1600–1612.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1600–1612
Mots-clés : practice of OR; transport; energy; inventory; linear programming Index. décimale : 001.424 Résumé : The use of forest fuel is increasing at heating plants in Sweden. Heating plants provide energy in the form of hot water for heating houses and apartments in local municipalities. Forest fuel are products obtained from harvesting in forests that cannot be used for further processing at sawmills and pulp and paper mills. Examples of such products are tree branches, tree tops and low quality logs. The optimization of the supply chain for round-wood (logs to sawmills, pulp and paper mills) and for forest fuel is similar but involves two main differences. First, forest fuel has to be converted into chips before delivery to the customer, and second, the demand for forest fuel varies over the year due to the temperature. To balance the chipping and transportation capacities over time, it is important to manage inventory levels at terminals. The optimization model developed provides decision support for questions regarding the choice of technology for chipping, where to perform the chipping operations, and the allocation of different assortments to heating plants. The system has been tested on a large case study from a Swedish forest energy company. The results show large savings and that the system is very useful for both planning and business development. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011157a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1613–1630
Titre : Three time-based scale formulations for the two-stage lot sizing and scheduling in process industries Type de document : texte imprimé Auteurs : V. C. B. Camargo, Auteur ; F. M. B. Toledo, Auteur ; B. Almada-Lobo, Auteur Année de publication : 2012 Article en page(s) : pp. 1613–1630 Note générale : operational research Langues : Anglais (eng) Mots-clés : lot sizing and scheduling; two-stage production system; mixed-integer program; time scale Index. décimale : 001.424 Résumé : In this paper, we propose three novel mathematical models for the two-stage lot-sizing and scheduling problems present in many process industries. The problem shares a continuous or quasi-continuous production feature upstream and a discrete manufacturing feature downstream, which must be synchronized. Different time-based scale representations are discussed. The first formulation encompasses a discrete-time representation. The second one is a hybrid continuous-discrete model. The last formulation is based on a continuous-time model representation. Computational tests with state-of-the-art MIP solver show that the discrete-time representation provides better feasible solutions in short running time. On the other hand, the hybrid model achieves better solutions for longer computational times and was able to prove optimality more often. The continuous-type model is the most flexible of the three for incorporating additional operational requirements, at a cost of having the worst computational performance. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011159a.html [article] Three time-based scale formulations for the two-stage lot sizing and scheduling in process industries [texte imprimé] / V. C. B. Camargo, Auteur ; F. M. B. Toledo, Auteur ; B. Almada-Lobo, Auteur . - 2012 . - pp. 1613–1630.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1613–1630
Mots-clés : lot sizing and scheduling; two-stage production system; mixed-integer program; time scale Index. décimale : 001.424 Résumé : In this paper, we propose three novel mathematical models for the two-stage lot-sizing and scheduling problems present in many process industries. The problem shares a continuous or quasi-continuous production feature upstream and a discrete manufacturing feature downstream, which must be synchronized. Different time-based scale representations are discussed. The first formulation encompasses a discrete-time representation. The second one is a hybrid continuous-discrete model. The last formulation is based on a continuous-time model representation. Computational tests with state-of-the-art MIP solver show that the discrete-time representation provides better feasible solutions in short running time. On the other hand, the hybrid model achieves better solutions for longer computational times and was able to prove optimality more often. The continuous-type model is the most flexible of the three for incorporating additional operational requirements, at a cost of having the worst computational performance. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011159a.html
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1631–1633
Titre : Some comments on MacKay's Lanchester mixed forces model Type de document : texte imprimé Auteurs : P. L. Liu, Auteur ; H. K. Sun, Auteur ; Y. T. You, Auteur Année de publication : 2012 Article en page(s) : pp. 1631–1633 Note générale : operational research Langues : Anglais (eng) Index. décimale : 001.424 DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011162a.html [article] Some comments on MacKay's Lanchester mixed forces model [texte imprimé] / P. L. Liu, Auteur ; H. K. Sun, Auteur ; Y. T. You, Auteur . - 2012 . - pp. 1631–1633.
operational research
Langues : Anglais (eng)
in Journal of the operational research society (JORS) > Vol. 63 N° 11 (Novembre 2012) . - pp. 1631–1633
Index. décimale : 001.424 DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v63/n11/abs/jors2011162a.html
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