Phuc Do Van

Dynamic grouping maintenance with time limited opportunities

This paper presents firstly a dynamic grouping maintenance strategy for multi-component systems with positive economic dependence, which implies that combining maintenance activities is cheaper than performing maintenance on components separately. Preventive maintenance durations and multiple occurrences of maintenance activities within scheduling horizon are considered. Moreover, in a dynamic context, maintenance opportunities, defined as inactivity periods of the systems at which several maintenance activities could be executed with reduced maintenance costs, may randomly occur with time. The second objective of the paper is to propose a new algorithm to optimally update online the grouped maintenance planning by taking into account the maintenance opportunities. A numerical example of a five components system is finally introduced to illustrate the proposed dynamic grouping maintenance strategy.

Reliability importance analysis of Markovian systems at steady state using perturbation analysis

Sensitivity analysis has been primarily defined for static systems, i.e. systems described by combinatorial reliability models (fault or event trees). Several structural and probabilistic measures have been proposed to assess the components importance. For dynamic systems including inter-component and functional dependencies (cold spare, shared load, shared resources, etc.), and described by Markov models or, more generally, by discrete events dynamic systems models, the problem of sensitivity analysis remains widely open. In this paper, the perturbation method is used to estimate an importance factor, called multi-directional sensitivity measure, in the framework of Markovian systems. Some numerical examples are introduced to show why this method offers a promising tool for steady-state sensitivity analysis of Markov processes in reliability studies.

Condition‐Based Maintenance with Imperfect Preventive Repairs for a Deteriorating Production System

This paper presents a condition-based maintenance policy considering aspects of maintenance cost and productivity for a single unit deteriorating production system whose condition is periodically monitored. Imperfect preventive maintenance actions, which restore the production system to better than old, are considered with both deterministic and random intervention gains. Moreover the system is assumed to be repaired only a limited number of times. In order to assess the performance of the proposed maintenance policy, different types of imperfect preventive maintenance cost functions are investigated. A numerical example of a multi state production system is finally introduced to illustrate the use and the advantages of the proposed policy.

From differential to difference importance measures for Markov reliability models

This paper presents the development of the differential importance measures (DIM), proposed recently for the use in risk-informed decision-making, in the context of Markov reliability models. The proposed DIM are essentially based on directional derivatives. They can be used to quantify the relative contribution of a component (or a group of components, a state or a group of states) of the system on the total variation of system performance provoked by the changes in system parameters values. The estimation of DIM at steady state using only a single sample path of a Markov process is also investigated. A numerical example of a dynamic system is finally introduced to illustrate the use of DIM, as well as the advantages of proposed evaluation approaches.

Grouping maintenance strategy with availability constraint under limited repairmen

The paper deals with a development of the rolling horizon approach introduced recently for grouping maintenance strategies of multi-component systems by integrating two efficient optimization algorithms. The proposed approach can help to construct an optimal maintenance planning with a given availability constraint under limited repairmen. Thanks to the rolling horizon spirit, the maintenance planning can be updated to take into account short-term information which could be changed with time. A numerical example of a multi-component system is finally introduced to illustrate the use and the advantages of the proposed approach in the maintenance optimization framework.

Condition based maintenance model for a production deteriorating system

This paper addresses a condition based maintenance model taking into account both maintenance cost and production capacity aspects for a single unit production system whose condition is monitored by inspection relying on an aperiodic inspection schedule. In order to assess the performance of the proposed maintenance policy, maintenance cost per unit of product is introduced and calculated analytically. A numerical example of a multi state production system is finally introduced to illustrate the performance of the proposed policy, as well as the advantages of proposed evaluation approach.

Remaining useful life (RUL) based maintenance decision making for deteriorating systems

This paper deals with a remaining useful life (RUL) based maintenance policy for single unit deteriorating systems whose condition are periodically monitored. Thank to the RUL information, which is estimated from the available monitoring information, various decisions related to inspections, logistic support, maintenance opportunities and maintenance actions are considered in the proposed policy. To illustrate the use and the advantages of the proposed maintenance policy, different sensitivity studies are analyzed and discussed through a numerical example. A comparaison with a classical condition based maintenance policy is also investigated.

Dynamic grouping maintenance for complex structure systems with non-negligible replacement time

This paper presents a dynamic grouping maintenance strategy for complex systems whose structure may lead to both positive and negative economic dependencies. Preventive maintenance (PM) durations are investigated and considered in the proposed maintenance model. Thanks to the rolling horizon spirit, the maintenance planning can be updated to take into account short-term information which could be changed with time. Moreover, Genetic Algorithm (GA) is used to find the optimal grouping planning which is NP-hard combinatorial problem. A numerical example of a 10 components system is finally introduced to illustrate the use and the advantages of the proposed approach in the maintenance optimization framework.

Considération d’un indicateur d’efficacité énergétique pour la prise de décision en maintenance. De sa définition au fondement de son pronostic

Ce papier a pour objet d’investiguer la problematique de consideration de l’efficacite energetique et de sa prevision comme nouvel indicateur dans la prise de decision en maintenance. En ce sens, le papier positionne tout d’abord les differentes definitions et concepts de l’efficacite energetique en general, pour ensuite les particulariser au domaine industriel. Chaque concept est ainsi analyse et nous discutons de la pertinence de leur utilisation a differents niveaux de decision. Ceci nous permet de proposer une approche multi niveau d’evaluation d’un indicateur de l’efficacite energetique d’un systeme industriel. L’evolution temporelle de cet indicateur en regard de la degradation du systeme est ensuite abordee dans un objectif de maintenance previsionnelle. Cela nous amene a proposer, en dual du concept connu de RUL (Remaining Useful Life), le concept de REEL representant la duree de vie energetique residuelle. Des approches de pronostic de l’indicateur d’efficacite energetique sont par consequent investiguees pour permettre le calcul de cette REEL. Enfin, nous appliquons le concept d’efficacite energetique propose et montrons la valeur ajoutee de notre approche pour le pronostic de l’indicateur d’efficacite energetique sur plusieurs niveaux de la plateforme laboratoire en telemaintenance TELMA.