Dépouillements

Optimal inspection intervals for safety systems with partial inspections / Pascual, R. in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2051–2062 Titre : Optimal inspection intervals for safety systems with partial inspections Type de document : texte imprimé Auteurs : Pascual, R., Auteur ; Louit, D., Auteur ; Jardine, A. K. S., Auteur Année de publication : 2011 Article en page(s) : pp. 2051–2062 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Safety  system  Availability  IEC  61508  Redundancy  Coverage  ratio  Partial  inspection Index. décimale : 001.424 Résumé : The introduction of International Standard IEC 61508 and its industry-specific derivatives sets demanding requirements for the definition and implementation of life-cycle strategies for safety systems. Compliance with the Standard is important for human safety and environmental perspectives as well as for potential adverse economic effects (eg, damage to critical downstream equipment or a clause for an insurance or warranty contract). This situation encourages the use of reliability models to attain the recommended safety integrity levels using credible assumptions. During the operation phase of the safety system life cycle, a key decision is the definition of an inspection programme, namely its frequency and the maintenance activities to be performed. These may vary from minimal checks to complete renewals. This work presents a model (which we called ρβ model) to find optimal inspection intervals for a safety system, considering that it degrades in time, even when it is inspected at regular intervals. Such situation occurs because most inspections are partial, that is, not all potential failure modes are observable through inspections. Possible reasons for this are the nature and the extent of the inspection, or potential risks generated by the inspection itself. The optimization criterion considered here is the mean overall availability Ao, but also taking into account the requirements for the safety availability As. We consider several conditions that ensure coherent modelling for these systems: sub-systems decomposition, k-out-of-n architectures, diagnostics coverage (observable/total amount of failure modes), dependent and independent failures, and non-negligible inspection times. The model requires an estimation for the coverage and dependent-failure ratios for each component, global failure rates, and inspection times. We illustrate its use through case studies and compare results with those obtained by applying previously published methodologies. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010173a.html [article] Optimal inspection intervals for safety systems with partial inspections [texte imprimé] / Pascual, R., Auteur ; Louit, D., Auteur ; Jardine, A. K. S., Auteur . - 2011 . - pp. 2051–2062. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2051–2062 Mots-clés : Safety  system  Availability  IEC  61508  Redundancy  Coverage  ratio  Partial  inspection Index. décimale : 001.424 Résumé : The introduction of International Standard IEC 61508 and its industry-specific derivatives sets demanding requirements for the definition and implementation of life-cycle strategies for safety systems. Compliance with the Standard is important for human safety and environmental perspectives as well as for potential adverse economic effects (eg, damage to critical downstream equipment or a clause for an insurance or warranty contract). This situation encourages the use of reliability models to attain the recommended safety integrity levels using credible assumptions. During the operation phase of the safety system life cycle, a key decision is the definition of an inspection programme, namely its frequency and the maintenance activities to be performed. These may vary from minimal checks to complete renewals. This work presents a model (which we called ρβ model) to find optimal inspection intervals for a safety system, considering that it degrades in time, even when it is inspected at regular intervals. Such situation occurs because most inspections are partial, that is, not all potential failure modes are observable through inspections. Possible reasons for this are the nature and the extent of the inspection, or potential risks generated by the inspection itself. The optimization criterion considered here is the mean overall availability Ao, but also taking into account the requirements for the safety availability As. We consider several conditions that ensure coherent modelling for these systems: sub-systems decomposition, k-out-of-n architectures, diagnostics coverage (observable/total amount of failure modes), dependent and independent failures, and non-negligible inspection times. The model requires an estimation for the coverage and dependent-failure ratios for each component, global failure rates, and inspection times. We illustrate its use through case studies and compare results with those obtained by applying previously published methodologies. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010173a.html

Perishable inventory management system with a minimum volume constraint / Z. Shen in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2063–2082 Titre : Perishable inventory management system with a minimum volume constraint Type de document : texte imprimé Auteurs : Z. Shen, Auteur ; M. Dessouky, Auteur ; F. Ordonez, Auteur Année de publication : 2011 Article en page(s) : pp. 2063–2082 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Perishable  inventory  management  EMQ  Non-convex  unconstrained  optimization  problem  Emergency  response  VMI  Pharmaceutical  inventory  management Index. décimale : 001.424 Résumé : The federal government maintains large quantities of medical supplies in stock as part of its Strategic National Stockpile (SNS) to protect the American public in case of a public health emergency. Managing these large perishable inventories effectively can help reduce the cost of the SNS and improves national security. In this paper, we propose a modified Economic Manufacturing Quantity (EMQ) model for perishable inventory with a minimum volume constraint, which is applicable to managing the inventory of medicines for the Strategic National Stockpile. We demonstrate that minimizing the cost of maintaining such a system can be formulated as a non-convex non-smooth unconstrained optimization problem. The property of this model is analysed and an efficient exact algorithm is presented to solve this problem. In the numerical experiment part, we perform sensitivity analysis on several government-controlled system parameters to illustrate how the government can obtain lower costs or a larger stockpile at the same cost by allowing more freedom in the management of the stocks. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010181a.html [article] Perishable inventory management system with a minimum volume constraint [texte imprimé] / Z. Shen, Auteur ; M. Dessouky, Auteur ; F. Ordonez, Auteur . - 2011 . - pp. 2063–2082. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2063–2082 Mots-clés : Perishable  inventory  management  EMQ  Non-convex  unconstrained  optimization  problem  Emergency  response  VMI  Pharmaceutical  inventory  management Index. décimale : 001.424 Résumé : The federal government maintains large quantities of medical supplies in stock as part of its Strategic National Stockpile (SNS) to protect the American public in case of a public health emergency. Managing these large perishable inventories effectively can help reduce the cost of the SNS and improves national security. In this paper, we propose a modified Economic Manufacturing Quantity (EMQ) model for perishable inventory with a minimum volume constraint, which is applicable to managing the inventory of medicines for the Strategic National Stockpile. We demonstrate that minimizing the cost of maintaining such a system can be formulated as a non-convex non-smooth unconstrained optimization problem. The property of this model is analysed and an efficient exact algorithm is presented to solve this problem. In the numerical experiment part, we perform sensitivity analysis on several government-controlled system parameters to illustrate how the government can obtain lower costs or a larger stockpile at the same cost by allowing more freedom in the management of the stocks. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010181a.html

Metaheuristics for scheduling jobs with incompatible families on parallel batching machines / C. Almeder in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2083–2096 Titre : Metaheuristics for scheduling jobs with incompatible families on parallel batching machines Type de document : texte imprimé Auteurs : C. Almeder, Auteur ; L. Mönch, Auteur Année de publication : 2011 Article en page(s) : pp. 2083–2096 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Batching  Scheduling  Ant  colony  optimization  Variable  neighbourhood  search  Total  weighted  tardiness Index. décimale : 001.424 Résumé : In this paper, we discuss the scheduling of jobs with incompatible families on parallel batching machines. The performance measure is total weighted tardiness. This research is motivated by a scheduling problem found in the diffusion and oxidation areas of semiconductor wafer fabrication where the machines can be modelled as parallel batch processors. Given that this scheduling problem is NP-hard, we suggest an ant colony optimization (ACO) and a variable neighbourhood search (VNS) approach. Both metaheuristics are hybridized with a decomposition heuristic and a local search scheme. We compare the performance of the two algorithms with that of a genetic algorithm (GA) based on extensive computational experiments. The VNS approach outperforms the ACO and GA approach with respect to time and solution quality. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010186a.html [article] Metaheuristics for scheduling jobs with incompatible families on parallel batching machines [texte imprimé] / C. Almeder, Auteur ; L. Mönch, Auteur . - 2011 . - pp. 2083–2096. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2083–2096 Mots-clés : Batching  Scheduling  Ant  colony  optimization  Variable  neighbourhood  search  Total  weighted  tardiness Index. décimale : 001.424 Résumé : In this paper, we discuss the scheduling of jobs with incompatible families on parallel batching machines. The performance measure is total weighted tardiness. This research is motivated by a scheduling problem found in the diffusion and oxidation areas of semiconductor wafer fabrication where the machines can be modelled as parallel batch processors. Given that this scheduling problem is NP-hard, we suggest an ant colony optimization (ACO) and a variable neighbourhood search (VNS) approach. Both metaheuristics are hybridized with a decomposition heuristic and a local search scheme. We compare the performance of the two algorithms with that of a genetic algorithm (GA) based on extensive computational experiments. The VNS approach outperforms the ACO and GA approach with respect to time and solution quality. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010186a.html

Valuing internet companies / C-TB. Ho in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2097–2106 Titre : Valuing internet companies : a DEA-based Multiple Valuation Approach Type de document : texte imprimé Auteurs : C-TB. Ho, Auteur ; C-K. Liao, Auteur ; H-T. Kim, Auteur Année de publication : 2011 Article en page(s) : pp. 2097–2106 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Data  envelopment  analysis  (DEA)  Multiple  valuation  approach  Internet  company  Investment  analysis Index. décimale : 001.424 Résumé : The Internet industry has created a great deal of marvels over the past decade. Assessing Internet companies’ values provides an alternative tool to help make better investment decisions. This paper presents a hybrid of both DEA and multiple valuation methods to valuate Internet companies. Four tailored valuation methods were proposed and a sample of 52 firms was tested based on Price-to-Gross Margin ratio. With the focus on the estimation direction (overvalued/undervalued), verified with the real prices, an accuracy rate of approximately 70% on average has been obtained from these four methods. The proposed methods allow investors to have a more accurate estimation of the subject company's current and future stock prices. This implies that the research results could help investors when they are making long-term or short-term investments. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010191a.html [article] Valuing internet companies : a DEA-based Multiple Valuation Approach [texte imprimé] / C-TB. Ho, Auteur ; C-K. Liao, Auteur ; H-T. Kim, Auteur . - 2011 . - pp. 2097–2106. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2097–2106 Mots-clés : Data  envelopment  analysis  (DEA)  Multiple  valuation  approach  Internet  company  Investment  analysis Index. décimale : 001.424 Résumé : The Internet industry has created a great deal of marvels over the past decade. Assessing Internet companies’ values provides an alternative tool to help make better investment decisions. This paper presents a hybrid of both DEA and multiple valuation methods to valuate Internet companies. Four tailored valuation methods were proposed and a sample of 52 firms was tested based on Price-to-Gross Margin ratio. With the focus on the estimation direction (overvalued/undervalued), verified with the real prices, an accuracy rate of approximately 70% on average has been obtained from these four methods. The proposed methods allow investors to have a more accurate estimation of the subject company's current and future stock prices. This implies that the research results could help investors when they are making long-term or short-term investments. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010191a.html

Service network design for freight railway transportation / G. Lulli in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2107–2119 Titre : Service network design for freight railway transportation : the Italian case Type de document : texte imprimé Auteurs : G. Lulli, Auteur ; U. Pietropaoli, Auteur ; N. Ricciardi, Auteur Année de publication : 2011 Article en page(s) : pp. 2107–2119 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Rail  transportation  Service  network  design  Practice  of  OR  Tabu  search Index. décimale : 001.424 Résumé : In this paper, we present a case study on freight railway transportation in Italy, which is a by-product of research collaboration with a major Italian railway company. We highlight the main features of the Italian reality and propose a customized mathematical model to design the service network, that is, the set of origin-destination connections. More specifically, the model suggests the services to provide, the number of trains travelling on each connection, the number of cars and their type. We consider both full and empty freight car movements and take handling costs into account. All decisions are taken in order to minimize the total costs. The quality of service is guaranteed by satisfying all the transportation demand and by implicitly minimizing the waiting time of cars at intermediate railway stations. Our approach yields to a multi-commodity network design problem with a concave cost function. To solve this problem, we implement a specialized tabu search procedure. Computational results on realistic instances show a significant improvement over current practice. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010190a.html [article] Service network design for freight railway transportation : the Italian case [texte imprimé] / G. Lulli, Auteur ; U. Pietropaoli, Auteur ; N. Ricciardi, Auteur . - 2011 . - pp. 2107–2119. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2107–2119 Mots-clés : Rail  transportation  Service  network  design  Practice  of  OR  Tabu  search Index. décimale : 001.424 Résumé : In this paper, we present a case study on freight railway transportation in Italy, which is a by-product of research collaboration with a major Italian railway company. We highlight the main features of the Italian reality and propose a customized mathematical model to design the service network, that is, the set of origin-destination connections. More specifically, the model suggests the services to provide, the number of trains travelling on each connection, the number of cars and their type. We consider both full and empty freight car movements and take handling costs into account. All decisions are taken in order to minimize the total costs. The quality of service is guaranteed by satisfying all the transportation demand and by implicitly minimizing the waiting time of cars at intermediate railway stations. Our approach yields to a multi-commodity network design problem with a concave cost function. To solve this problem, we implement a specialized tabu search procedure. Computational results on realistic instances show a significant improvement over current practice. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010190a.html

Towards a methodology for measuring the true degree of efficiency in a speculative market / S. Lessmann in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2120–2132 Titre : Towards a methodology for measuring the true degree of efficiency in a speculative market Type de document : texte imprimé Auteurs : S. Lessmann, Auteur ; M-C. Sung, Auteur ; J. E. V. Johnson, Auteur Année de publication : 2011 Article en page(s) : pp. 2120–2132 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Forecasting  accuracy  Market  efficiency  Point  estimates  Betting  markets Index. décimale : 001.424 Résumé : Betting markets have drawn much attention in the economics, finance and operational research literature because they provide a valuable window on the manner in which individuals use information in wider financial markets. One question that has received particular attention is to what extent individuals discount information in market prices. The predominant approach to explore this issue involves predictive modeling to forecast market outcomes and examining empirically whether abnormal returns can be made by employing these forecasts. It is argued here that present practices to assess such forecasting models, including the use of point estimates and information, which would not be available in practice (at the forecasting stage) and failing to update forecasting models with information from the recent past, may give rise to misleading conclusions regarding a market's informational efficiency. Hypotheses are developed to conceptualize these views and are tested by means of extensive empirical experimentation using real-world data from the Hong Kong horserace betting market. Our study identifies several sources of bias and confirms that current practices may not be relied upon. A more appropriate modeling procedure for assessing the true degree of market efficiency is then proposed. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010192a.html [article] Towards a methodology for measuring the true degree of efficiency in a speculative market [texte imprimé] / S. Lessmann, Auteur ; M-C. Sung, Auteur ; J. E. V. Johnson, Auteur . - 2011 . - pp. 2120–2132. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2120–2132 Mots-clés : Forecasting  accuracy  Market  efficiency  Point  estimates  Betting  markets Index. décimale : 001.424 Résumé : Betting markets have drawn much attention in the economics, finance and operational research literature because they provide a valuable window on the manner in which individuals use information in wider financial markets. One question that has received particular attention is to what extent individuals discount information in market prices. The predominant approach to explore this issue involves predictive modeling to forecast market outcomes and examining empirically whether abnormal returns can be made by employing these forecasts. It is argued here that present practices to assess such forecasting models, including the use of point estimates and information, which would not be available in practice (at the forecasting stage) and failing to update forecasting models with information from the recent past, may give rise to misleading conclusions regarding a market's informational efficiency. Hypotheses are developed to conceptualize these views and are tested by means of extensive empirical experimentation using real-world data from the Hong Kong horserace betting market. Our study identifies several sources of bias and confirms that current practices may not be relied upon. A more appropriate modeling procedure for assessing the true degree of market efficiency is then proposed. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010192a.html

A branching scheme for minimum cost tournaments with regard to real-world constraints / D. Briskorn in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2133–2145 Titre : A branching scheme for minimum cost tournaments with regard to real-world constraints Type de document : texte imprimé Auteurs : D. Briskorn, Auteur Année de publication : 2011 Article en page(s) : pp. 2133–2145 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Sports  league  scheduling  Round  robin  tournaments  Home-away-pattern  set  Break  Stadium  Region  Branch-and-bound Index. décimale : 001.424 Résumé : Single round robin tournaments are a well-known class of sports leagues schedules. We consider leagues with a set T of n teams where n is even. Costs are associated with each possible match. Moreover, stadium availability, fixed matches, and regions’ capacities are taken into account. The goal is to find the minimum cost tournament among those having the minimum number of breaks and being feasible with regard to these additional constraints. A branching scheme is developed where branching is done by fixing a break for a team. Thus, the focus is on identifying breaks leading to an infeasible home away pattern set in order to avoid the resulting infeasible subtrees of a branch and bound tree. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010185a.html [article] A branching scheme for minimum cost tournaments with regard to real-world constraints [texte imprimé] / D. Briskorn, Auteur . - 2011 . - pp. 2133–2145. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2133–2145 Mots-clés : Sports  league  scheduling  Round  robin  tournaments  Home-away-pattern  set  Break  Stadium  Region  Branch-and-bound Index. décimale : 001.424 Résumé : Single round robin tournaments are a well-known class of sports leagues schedules. We consider leagues with a set T of n teams where n is even. Costs are associated with each possible match. Moreover, stadium availability, fixed matches, and regions’ capacities are taken into account. The goal is to find the minimum cost tournament among those having the minimum number of breaks and being feasible with regard to these additional constraints. A branching scheme is developed where branching is done by fixing a break for a team. Thus, the focus is on identifying breaks leading to an infeasible home away pattern set in order to avoid the resulting infeasible subtrees of a branch and bound tree. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010185a.html

A new approach in modelling undesirable output in DEA modelstar / S. You in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2146–2156 Titre : A new approach in modelling undesirable output in DEA modelstar Type de document : texte imprimé Auteurs : S. You, Auteur ; H. Yan, Auteur Année de publication : 2011 Article en page(s) : pp. 2146–2156 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Data  Envelopment  Analysis  Undesirable  output  Efficiency  Ecological  extension  Textile  industry Index. décimale : 001.424 Résumé : With an increasing attention on the environment, one of the major research thrusts in Data Envelopment Analysis (DEA) based performance evaluation is the undesirable output in the conventional DEA model. There is considerable research published on the undesirable aspects of production outputs. However, the economic implications and the suitability of the DEA models for incorporating the undesirable outputs are less carefully investigated and discussed. In this paper, a comparative study is conducted of typical eco-DEA models to illustrate this issue. We propose a ratio model to evaluate the undesirable as well as the desirable outputs simultaneously. We apply the specially developed model to investigate the impact of production pollutants while conducting the efficiency evaluation in the textile industry of China. The results reveal that the production output-oriented efficiency evaluation can be significantly altered once the environmental aspects are factored into the model. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors20111a.html [article] A new approach in modelling undesirable output in DEA modelstar [texte imprimé] / S. You, Auteur ; H. Yan, Auteur . - 2011 . - pp. 2146–2156. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2146–2156 Mots-clés : Data  Envelopment  Analysis  Undesirable  output  Efficiency  Ecological  extension  Textile  industry Index. décimale : 001.424 Résumé : With an increasing attention on the environment, one of the major research thrusts in Data Envelopment Analysis (DEA) based performance evaluation is the undesirable output in the conventional DEA model. There is considerable research published on the undesirable aspects of production outputs. However, the economic implications and the suitability of the DEA models for incorporating the undesirable outputs are less carefully investigated and discussed. In this paper, a comparative study is conducted of typical eco-DEA models to illustrate this issue. We propose a ratio model to evaluate the undesirable as well as the desirable outputs simultaneously. We apply the specially developed model to investigate the impact of production pollutants while conducting the efficiency evaluation in the textile industry of China. The results reveal that the production output-oriented efficiency evaluation can be significantly altered once the environmental aspects are factored into the model. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors20111a.html

Effects of the information presentation format on project control / Ö Hazir in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2157–2161 Titre : Effects of the information presentation format on project control Type de document : texte imprimé Auteurs : Ö Hazir, Auteur ; Shtub, A., Auteur Année de publication : 2011 Article en page(s) : pp. 2157–2161 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Project  management  Project  control  Simulation  Earned  value  analysis Index. décimale : 001.424 Résumé : In this paper, we investigate the relationship between the information presentation format and project control. Furthermore, the effects of some system conditions, namely the number of projects to be controlled and the level of time pressure, on the quality of the project control decisions are analyzed. Information provided by Earned Value Analysis is used to monitor and control projects, and simulation is applied to replicate and model the uncertain project environments. Software is developed to generate random cost figures, to present the data in different visual forms and to collect users’ responses. Having performed the experiments, the statistical significance of the results is tested. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors201111a.html [article] Effects of the information presentation format on project control [texte imprimé] / Ö Hazir, Auteur ; Shtub, A., Auteur . - 2011 . - pp. 2157–2161. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2157–2161 Mots-clés : Project  management  Project  control  Simulation  Earned  value  analysis Index. décimale : 001.424 Résumé : In this paper, we investigate the relationship between the information presentation format and project control. Furthermore, the effects of some system conditions, namely the number of projects to be controlled and the level of time pressure, on the quality of the project control decisions are analyzed. Information provided by Earned Value Analysis is used to monitor and control projects, and simulation is applied to replicate and model the uncertain project environments. Software is developed to generate random cost figures, to present the data in different visual forms and to collect users’ responses. Having performed the experiments, the statistical significance of the results is tested. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors201111a.html

The training institution efficiency of the semiconductor institute programme in Taiwan / L-J. Kao in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2162–2172 Titre : The training institution efficiency of the semiconductor institute programme in Taiwan : application of spatiotemporal ICA with DEA approach Type de document : texte imprimé Auteurs : L-J. Kao, Auteur ; C-C. Lu, Auteur ; C-C. Chiu, Auteur Année de publication : 2011 Article en page(s) : pp. 2162–2172 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Data  envelopment  analysis  Spatiotemporal  independent  component  analysis  Efficiency  measurement  Training  institutions  Tobit–Bayes  regression Index. décimale : 001.424 Résumé : Despite the fact that Taiwan’s high-tech industry has gradually secured a leading position in the world, enterprises in Taiwan have striven to strengthen their technical advancement by providing employees with various internal or external training programmes. These institutional training programmes are designed to sustain competitive advantage, enhance the quality of manpower and improve operational efficiency. Much literature assesses the efficiency of an internal training programme that is initiated by a firm, but only a little literature studies the efficiency of an external training programme that is led by a government. Various efficiency measurement tools, such as conventional statistical methods and non-parametric methods, have been successfully developed in the literature. Among these tools, the data envelopment analysis (DEA) approach is one of the most widely discussed. However, the DEA's capability to discriminate efficient decision-making units from inefficient decision-making units requires much improvement (Adler and Yazhemsky). In this paper, a two-stage approach of integrating spatiotemporal independent component analysis (stICA) and DEA is developed for efficiency measurement. stICA is used to search for latent source signals where no relevant signal mixture mechanisms are available; and DEA is used to measure the relative efficiencies of decision-making units (DMUs). We suggest using stICA first to extract the input variables for generating independent components (IC), then selecting the ICs representing the independent sources of input variables, and finally inputting the selected ICs as new variables in the DEA model. To find the effects of environmental variables on the estimated efficiency scores, the Tobit–Bayes (censored) regression is applied. A simulated dataset and the training institution dataset provided by the Semiconductor Institute in Taiwan is used for analysis. The empirical result shows that the proposed method can not only separate performance differences between the training institutions but also improve the discriminatory capability of the DEA's efficiency measurement. The study results can serve as a reference for training institutions wishing to enhance their training efficiency. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010177a.html [article] The training institution efficiency of the semiconductor institute programme in Taiwan : application of spatiotemporal ICA with DEA approach [texte imprimé] / L-J. Kao, Auteur ; C-C. Lu, Auteur ; C-C. Chiu, Auteur . - 2011 . - pp. 2162–2172. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2162–2172 Mots-clés : Data  envelopment  analysis  Spatiotemporal  independent  component  analysis  Efficiency  measurement  Training  institutions  Tobit–Bayes  regression Index. décimale : 001.424 Résumé : Despite the fact that Taiwan’s high-tech industry has gradually secured a leading position in the world, enterprises in Taiwan have striven to strengthen their technical advancement by providing employees with various internal or external training programmes. These institutional training programmes are designed to sustain competitive advantage, enhance the quality of manpower and improve operational efficiency. Much literature assesses the efficiency of an internal training programme that is initiated by a firm, but only a little literature studies the efficiency of an external training programme that is led by a government. Various efficiency measurement tools, such as conventional statistical methods and non-parametric methods, have been successfully developed in the literature. Among these tools, the data envelopment analysis (DEA) approach is one of the most widely discussed. However, the DEA's capability to discriminate efficient decision-making units from inefficient decision-making units requires much improvement (Adler and Yazhemsky). In this paper, a two-stage approach of integrating spatiotemporal independent component analysis (stICA) and DEA is developed for efficiency measurement. stICA is used to search for latent source signals where no relevant signal mixture mechanisms are available; and DEA is used to measure the relative efficiencies of decision-making units (DMUs). We suggest using stICA first to extract the input variables for generating independent components (IC), then selecting the ICs representing the independent sources of input variables, and finally inputting the selected ICs as new variables in the DEA model. To find the effects of environmental variables on the estimated efficiency scores, the Tobit–Bayes (censored) regression is applied. A simulated dataset and the training institution dataset provided by the Semiconductor Institute in Taiwan is used for analysis. The empirical result shows that the proposed method can not only separate performance differences between the training institutions but also improve the discriminatory capability of the DEA's efficiency measurement. The study results can serve as a reference for training institutions wishing to enhance their training efficiency. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors2010177a.html

Productivity change in the water industry in England and Wales / M. C. A. S. Portela in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2173–2188 Titre : Productivity change in the water industry in England and Wales : application of the meta-Malmquist index Type de document : texte imprimé Auteurs : M. C. A. S. Portela, Auteur ; Thanassoulis, E., Auteur ; A. Horncastle, Auteur Année de publication : 2011 Article en page(s) : pp. 2173–2188 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Productivity  Malmquist  index  DEA  Water  companies Index. décimale : 001.424 Résumé : This paper uses a meta-Malmquist index for measuring productivity change of the water industry in England and Wales and compares this to the traditional Malmquist index. The meta-Malmquist index computes productivity change with reference to a meta-frontier, it is computationally simpler and it is circular. The analysis covers all 22 UK water companies in existence in 2007, using data over the period 1993–2007. We focus on operating expenditure in line with assessments in this field, which treat operating and capital expenditure as lacking substitutability. We find important improvements in productivity between 1993 and 2005, most of which were due to frontier shifts rather than catch up to the frontier by companies. After 2005, the productivity shows a declining trend. We further use the meta-Malmquist index to compare the productivities of companies at the same and at different points in time. This shows some interesting results relating to the productivity of each company relative to that of other companies over time, and also how the performance of each company relative to itself over 1993–2007 has evolved. The paper is grounded in the broad theory of methods for measuring productivity change, and more specifically on the use of circular Malmquist indices for that purpose. In this context, the contribution of the paper is methodological and applied. From the methodology perspective, the paper demonstrates the use of circular meta-Malmquist indices in a comparative context not only across companies but also within company across time. This type of within-company assessment using Malmquist indices has not been applied extensively and to the authors’ knowledge not to the UK water industry. From the application perspective, the paper throws light on the performance of UK water companies and assesses the potential impact of regulation on their performance. In this context, it updates the relevant literature using more recent data. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors201117a.html [article] Productivity change in the water industry in England and Wales : application of the meta-Malmquist index [texte imprimé] / M. C. A. S. Portela, Auteur ; Thanassoulis, E., Auteur ; A. Horncastle, Auteur . - 2011 . - pp. 2173–2188. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2173–2188 Mots-clés : Productivity  Malmquist  index  DEA  Water  companies Index. décimale : 001.424 Résumé : This paper uses a meta-Malmquist index for measuring productivity change of the water industry in England and Wales and compares this to the traditional Malmquist index. The meta-Malmquist index computes productivity change with reference to a meta-frontier, it is computationally simpler and it is circular. The analysis covers all 22 UK water companies in existence in 2007, using data over the period 1993–2007. We focus on operating expenditure in line with assessments in this field, which treat operating and capital expenditure as lacking substitutability. We find important improvements in productivity between 1993 and 2005, most of which were due to frontier shifts rather than catch up to the frontier by companies. After 2005, the productivity shows a declining trend. We further use the meta-Malmquist index to compare the productivities of companies at the same and at different points in time. This shows some interesting results relating to the productivity of each company relative to that of other companies over time, and also how the performance of each company relative to itself over 1993–2007 has evolved. The paper is grounded in the broad theory of methods for measuring productivity change, and more specifically on the use of circular Malmquist indices for that purpose. In this context, the contribution of the paper is methodological and applied. From the methodology perspective, the paper demonstrates the use of circular meta-Malmquist indices in a comparative context not only across companies but also within company across time. This type of within-company assessment using Malmquist indices has not been applied extensively and to the authors’ knowledge not to the UK water industry. From the application perspective, the paper throws light on the performance of UK water companies and assesses the potential impact of regulation on their performance. In this context, it updates the relevant literature using more recent data. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors201117a.html

Exemplaires

Bibliothèque Ecole Nationale Polytechnique d'Alger

Accueil

Se connecter

Météo

Adresse