Documents disponibles écrits par cet auteur

Bi-objective workforce-constrained maintenance scheduling: a case study / Safaei, N. in Journal of the operational research society (JORS), Vol. 62 N° 6 (Juin 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 6 (Juin 2011) . - pp. 1005–1018 Titre : Bi-objective workforce-constrained maintenance scheduling: a case study Type de document : texte imprimé Auteurs : Safaei, N., Auteur ; Banjevic, D., Auteur ; Jardine, A. K. S., Auteur Année de publication : 2011 Article en page(s) : pp. 1005–1018 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Workforce-constrained  maintenance  scheduling  Bi-objective  optimization  Mixed-integer  programming Index. décimale : 001.424 Résumé : In this paper, a real maintenance workforce-constrained scheduling problem is formulated as a bi-objective mixed-integer programming model with the aim of simultaneously minimizing the workforce requirements and maximizing the equipment availability. The skilled workforce is provided by internal and external resources using regular time, overtime and contracting. The equipment availability is measured by the downtime required for preventive maintenance (scheduled) and failure repair (unscheduled) jobs. We also encounter imminent or potential failures whose priorities depend on the severity of the failure on the system (secondary failure). The total weighted flow time is used as a scheduling criterion to measure the equipment availability; the weight of each job directly depends on the expected downtime resulting from the associated failure. The proposed model is verified using two comprehensive numerical examples and some sensitivity analyses. We conclude by discussing the results. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n6/abs/jors201051a.html [article] Bi-objective workforce-constrained maintenance scheduling: a case study [texte imprimé] / Safaei, N., Auteur ; Banjevic, D., Auteur ; Jardine, A. K. S., Auteur . - 2011 . - pp. 1005–1018. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 6 (Juin 2011) . - pp. 1005–1018 Mots-clés : Workforce-constrained  maintenance  scheduling  Bi-objective  optimization  Mixed-integer  programming Index. décimale : 001.424 Résumé : In this paper, a real maintenance workforce-constrained scheduling problem is formulated as a bi-objective mixed-integer programming model with the aim of simultaneously minimizing the workforce requirements and maximizing the equipment availability. The skilled workforce is provided by internal and external resources using regular time, overtime and contracting. The equipment availability is measured by the downtime required for preventive maintenance (scheduled) and failure repair (unscheduled) jobs. We also encounter imminent or potential failures whose priorities depend on the severity of the failure on the system (secondary failure). The total weighted flow time is used as a scheduling criterion to measure the equipment availability; the weight of each job directly depends on the expected downtime resulting from the associated failure. The proposed model is verified using two comprehensive numerical examples and some sensitivity analyses. We conclude by discussing the results. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n6/abs/jors201051a.html

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

Prioritization of medical equipment for maintenance decisions / S. Taghipour in Journal of the operational research society (JORS), Vol. 62 N° 9 (Septembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 9 (Septembre 2011) . - pp. 1666–1687 Titre : Prioritization of medical equipment for maintenance decisions Type de document : texte imprimé Auteurs : S. Taghipour, Auteur ; Banjevic, D., Auteur ; Jardine, A. K. S., Auteur Année de publication : 2011 Article en page(s) : pp. 1666–1687 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Medical  devices  Hospitals  Criticality  prioritization  Maintenance  decisions  Risk  MCDM  AHP Index. décimale : 001.424 Résumé : Clinical engineering departments in hospitals are responsible for establishing and regulating a Medical Equipment Management Program to ensure that medical devices are safe and reliable. In order to mitigate functional failures, significant and critical devices should be identified and prioritized. In this paper, we present a multi-criteria decision-making model to prioritize medical devices according to their criticality. Devices with lower criticality scores can be assigned a lower priority in a maintenance management program. However, those with higher scores should be investigated in detail to find the reasons for their higher criticality, and appropriate actions, such as ‘preventive maintenance’, ‘user training’, ‘redesigning the device’, etc, should be taken. In this paper,we also describe how individual score values obtained for each criterion can be used to establish guidelines for appropriate maintenance strategies for different classes of devices. The information of 26 different medical devices is extracted from a hospital's maintenance management system to illustrate an application of the proposed model. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n9/abs/jors2010106a.html [article] Prioritization of medical equipment for maintenance decisions [texte imprimé] / S. Taghipour, Auteur ; Banjevic, D., Auteur ; Jardine, A. K. S., Auteur . - 2011 . - pp. 1666–1687. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 9 (Septembre 2011) . - pp. 1666–1687 Mots-clés : Medical  devices  Hospitals  Criticality  prioritization  Maintenance  decisions  Risk  MCDM  AHP Index. décimale : 001.424 Résumé : Clinical engineering departments in hospitals are responsible for establishing and regulating a Medical Equipment Management Program to ensure that medical devices are safe and reliable. In order to mitigate functional failures, significant and critical devices should be identified and prioritized. In this paper, we present a multi-criteria decision-making model to prioritize medical devices according to their criticality. Devices with lower criticality scores can be assigned a lower priority in a maintenance management program. However, those with higher scores should be investigated in detail to find the reasons for their higher criticality, and appropriate actions, such as ‘preventive maintenance’, ‘user training’, ‘redesigning the device’, etc, should be taken. In this paper,we also describe how individual score values obtained for each criterion can be used to establish guidelines for appropriate maintenance strategies for different classes of devices. The information of 26 different medical devices is extracted from a hospital's maintenance management system to illustrate an application of the proposed model. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n9/abs/jors2010106a.html