Maintenance planning

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A novel solution approach with ML-based pseudo-cuts for the Flight and Maintenance Planning problem

A novel solution approach with ML-based pseudo-cuts for the Flight and Maintenance Planning problem

As stated previously, the uniform usage of the fleet is also a factor to take into account when choosing a correct maintenance planning. Given that the pattern selection is oriented towards constraining the check patterns that are too far from the predicted mean distance between checks, it is expected for the variance of this measure to decline. For the cases when there is more than one fleet type (i.e., for larger instances), the variances of each fleet type are calculated individually and

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Risk based inspection and maintenance planning of miter gates

Risk based inspection and maintenance planning of miter gates

The risk-based approach for inspection and maintenance planning is based on pre-posterior decision analysis concerning the two basic decision rules about inspection and repair. This paper discusses the methods to update the failure probability of welded joints considering crack inspection data by using Dynamic Bayesian Network. This method is useful for effective computation deterioration modeling, and failure probabilities can be updated rapidly. Risk-based inspection planning combines the updated probabilities with specific costs of failure, inspection, repair and annual discounting rate in order to estimate the operation and maintenance costs, which is a substantial part of the total expected costs during the service life.
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Maintenance Planning for Circular Economy: Laundromat Washing Machines Case

Maintenance Planning for Circular Economy: Laundromat Washing Machines Case

Functional economy is one among the various school of thought that make up Circular Economy. Instead of selling a product, manufacturers sell the service tied to the product. The direct consequence is that the more durable the product is, the most profitable it is to the manufacturer. Currently, in linear economy, the strategy of planned obsolescence allows the manufacturer to increase the demand and thus increase its profits at the expense of the customers and the environment. As the goal of functional economy is to make the product more durable, maintenance has an important role to play in it, and more generaly in circular economy. In the broadest sense, maintenance denotes any operation which can be com- pleted to increase the lifespan of a product already in use. Maintenance planning has been widely studied in the field of optimization, yet within this framework, brand-new objectives and constraints appear and have to be handled.
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Bi-objective MIP formulation for the optimization of maintenance planning on French military aircraft operations

Bi-objective MIP formulation for the optimization of maintenance planning on French military aircraft operations

ABSTRACT: A specific Flight and Maintenance Planning problem is presented. In this problem, preventive maintenance operations are scheduled for military aircraft along with the assignment of regular missions. The quality of the solutions is measured via a bi-objective function that smooths both maintenance operations and aircraft unavailability among time periods. A real world dataset provided by the French Air Force is used to test an exact optimization approach based on a Mixed Integer Programming model. Mono-objective computations are solved to optimality for medium size instances, allowing to compute exactly the Pareto frontier of the bi-objective optimization problems. The tests show that these two objectives do not lead to the same optimal solution, but very good compromise solutions can be found thanks to the bi-objective optimization.
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A novel MIP formulation for the optimization problem of maintenance planning of military aircraft

A novel MIP formulation for the optimization problem of maintenance planning of military aircraft

A novel MIP formulation for the optimization problem of maintenance planning of military aircraft ISAE-SUPAERO, Universit´e de Toulouse, France Franco Peschiera franco.peschiera@isae-sup[r]

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An Integrated Production and Maintenance Planning Model with time windows and shortage cost

An Integrated Production and Maintenance Planning Model with time windows and shortage cost

Currently, production planning and maintenance are performed separately. For instance, common ERP modules include production planning module that optimizes the utilization of manufacturing capacity, parts, components and material resources. Maintenance module is a peripheral module little known in fact, it is not part of core ERP application as production planning, finance, HR (Human Resources) Modules. it is considered as computerized maintenance management system (CMMS), and it allows managing preventive and corrective maintenance of all material assets of the company. We notice that each of these modules is used independently with specific data from each service, and no coordination is implemented to reduce production and maintenance costs. Therefore, maintenance planning should be an integral part of the overall business strategy and should be coordinated and scheduled with manufacturing activities. So, we should consider maintenance as integral parts of the production plan rather than as interruptions to that plan. Any violation of the maintenance schedule is treated as a violation of the production plan integrity.
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Lagrangian relaxation based heuristic for an integrated production and maintenance planning problem

Lagrangian relaxation based heuristic for an integrated production and maintenance planning problem

amount of demand shortages. The maintenance planning problem is to determine the dates of preventive maintenance in time windows according to reliability of production equipment and demand. When preventive maintenance actions are carried out the production line is restored to as good as new (AGAN) state, i.e. the system has the same lifetime distribution and failure

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Maintenance planning on French military aircraft operations

Maintenance planning on French military aircraft operations

Some resources can be in maintenance at the beginning of the planning horizon, nt is used for the number of aircraft in such planned maintenance per period t and defined only for the fir[r]

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2013 — Production and maintenance planning of deteriorating manufacturing systems taking into account the quality of products

2013 — Production and maintenance planning of deteriorating manufacturing systems taking into account the quality of products

139 In practice, preventive maintenance is widely applied in a number of industrial sectors to counter the effect of random failures and the loss of production. The effective implementation of preventive maintenance policies has been extensively studied as in Yulan et al. (2008) where the joint determination of preventive maintenance and production planning was presented. They considered an objective function, consisted of multiple objectives instead of a single objective as most of the literature. Furthermore Radhoui et al. (2010) develop a model for one machine system producing lots of product. In this model, they utilize the proportion of non-conforming units as decision variable to determine when to perform preventive maintenance. Also they define the size of the buffer stock. On their part, Dhouib et al. (2012) proposed a model that determines the production control and the age- based preventive maintenance policy that reduces the shift rate to the out of control state, where the system produces defective products. Recently, Rivera-Gómez et al. (2013) treated a deteriorating system where the quality of the parts decreases by the influence of the natural wear of the machine and imperfect repairs. In their model they defined an aging process through a set of operational states. In addition, they succeeded to determine the optimal production and repairs policies. As we can notice in the research works mentioned above, a few applications have dealt with preventive maintenance strategies for manufacturing systems producing defectives products. Nevertheless, a key observation is that none of them have considered the simultaneous effect of deterioration on the quality of the parts produced and the reliability of the system, and how their repercussions can be mitigated through preventive maintenance strategies. To an extent, our model addresses this drawback, extending previous models and assumptions.
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A trade-off between productivity and cost for the integrated part quality inspection and preventive maintenance planning under uncertainty

A trade-off between productivity and cost for the integrated part quality inspection and preventive maintenance planning under uncertainty

5. Conclusion and future research direction This work has presented a robust possibilistic, bi-objective, MILP model for the integrated planning problem of the PM and part quality inspection activities in deteriorating SMMSs. The proposed model specifies the optimum time and place for the PM and part quality inspection activities while simultaneously optimising two objectives: (1) system productivity (2) total cost. A non-linear utility function of produced conforming items was defined as a measure of system productivity and a piecewise linear approximation approach has been employed to deal with the non-linearity. This new objective function makes an opportunity for the manufacturing companies to establish a trade-off between system productivity and total cost which would be a great advantage in today’s competitive environment. In addition, a RPP approach has been used to handle the uncertainty which is rooted in the dynamic nature of the problem. Finally, a numerical example and a real case study have been investigated for the validation and verification purposes. The results show that the robust possibilistic approach decreases the variance of the total cost in any realisation of uncertain parameters in comparison to the deterministic approach. Hence, through applying the robust possibilistic approach, the fluctuations in the cost components cannot impose a huge unpredictable cost to the company.
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Dantzig-Wolfe decomposition and Lagrangean Relaxation based Heuristics for an Integrated Production and Maintenance planning with time windows and shortage cost

Dantzig-Wolfe decomposition and Lagrangean Relaxation based Heuristics for an Integrated Production and Maintenance planning with time windows and shortage cost

Abstract: In this paper, two approaches are developed to solve the integrated production planning and maintenance problem. Moreover, Some Propositions and mathematical properties were suggested and applied in the proposed heuristics to solve the problem. The first heuristic developed is based on Lagrangean relaxation (Lagrangean heuristic (LH)) and the second is based on Dantzig-Wolfe decomposition (Dantzig-Wolfe based heuristic (DWH)). The first heuristic is based on Dantzig-Wolfe decomposition (Dantzig and Wolfe, 1960). The Dantzig-Wolfe Decomposition principle reformulates the original model and Column generation is then used to deal with the huge number of variables of the reformulated model. A simple rounding heuristic and a smoothing procedure are finally carried out in order to obtain integer solutions. The second heuristic is based on Lagrangean relaxation (Fisher 1981) of the capacity constraints and sub-gradient optimization. At every step of sub-gradient method, feasibility and improvement procedures are applied to the solution of the Lagrangean problem. Computational experiments are carried out to show the results obtained by our approaches and compared to those of commercial solver.
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Probabilistic updating of corroded reinforced concrete pipes for maintenance planning optimisation

Probabilistic updating of corroded reinforced concrete pipes for maintenance planning optimisation

Strategies for replacement for these pipes depend on (1) the risks associated with failure of a water distribution network, and (2) the costs associated with replaci[r]

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POMDP-Based Risk Maintenance Planning  for Offshore Wind Substructures

POMDP-Based Risk Maintenance Planning for Offshore Wind Substructures

Sequential decision problem Calibration fracture mechanics – SN/Miner - reliability 5. CONCLUSION The optimal maintenance strategy for a tubular joint is identified by a 60-states “point-based” Partially Observable Markov Decision Process (POMDP). The obtained PODMP policy provides similar results as a common risk-based heuristic model.

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Presentation: Risk based inspection and maintenance planning of miter gates

Presentation: Risk based inspection and maintenance planning of miter gates

• The different stress-ranges occurring during the year are represented by an equivalent stress-range value. • A framework where Dynamic Bayesian network is used for risk-based inspection planning of a miter gate welded joint considering inspection data.

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Towards a hierarchical modelling approach for planning aircraft tail assignment and predictive maintenance

Towards a hierarchical modelling approach for planning aircraft tail assignment and predictive maintenance

Introduction Aircraft connectivity plays a promising role in operation cost reduction for airlines. Thanks to data collection of maintain- able systems some equipment can be monitored, and un- scheduled maintenance can be triggered by the evolution of the related health indicator (Wang, Chu, and Wu 2007). Note the visibility of upcoming failures can help to redefine the maintenance planning and reduce Aircraft On Ground (AOG) risk. In this context, predictive maintenance (Mobley 2002) aims to consider the real time values of health indica- tors, as well as their likely evolution, to plan unscheduled maintenance. However, specific aircraft routing is necessary to be able to perform maintenance in some cases. Thus, a planning model that controls routing allocation and mainte- nance actions could efficiently reduce operation costs.
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Fuzzy uncertainty modelling for project planning; application to helicopter maintenance

Fuzzy uncertainty modelling for project planning; application to helicopter maintenance

Maintenance is an activity of growing interest specially for critical systems. Particularly, aircraft maintenance costs are becoming an important issue in the aeronautical industry. Managing an aircraft maintenance center is a complex activity. One of the difficulties comes from the numerous uncertainties that affect the activity and disturb the plans at short and medium term. Based on a helicopter maintenance planning and scheduling problem, we study in this paper the integration of uncertainties into tactical and operational multi- resource, multi-project planning (respectively Rough Cut Capacity Planning and Resource Constraint Project Scheduling Problem). Our main contributions are in modelling the periodic workload on tactical level considering uncertain- ties in macro-tasks work contents, and modelling the continuous workload on operational level considering uncertainties in tasks durations. We model uncer- tainties by a fuzzy/possibilistic approach instead of a stochastic approach since very limited data are available. We refer to the problems as the Fuzzy Rough Cut Capacity Problem (FRCCP) and the Fuzzy Resource Constraint Project Scheduling Problem (RCPSP). We apply our models to helicopter maintenance activity within the frame of the Helimaintenance project, an industrial project approved by the French Aerospace Valley cluster which aims at building a center for civil helicopter maintenance.
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A decision support system for integrating corrective maintenance, preventive maintenance, and condition-based maintenance

A decision support system for integrating corrective maintenance, preventive maintenance, and condition-based maintenance

Figure 2: Preventive maintenance planning process In CMMS, “task list” function is provided to group maintenance tasks, but actually it is just a simple checklist-style reminder which cannot handle complex relationships nor consolidate external resource constraints required by the industry. To settle this dilemma, we combine the PM planning and project planning in the FMM-DSS framework, which treats them equally as “projects”. Treating all MOs as projects provides a good unification for maintenance orders and maintenance projects, which is one of the most distinguishing features of our framework. Complex relationships and constraints can therefore be defined on tasks and project scheduling techniques can easily be applied to resolve complex problems. We have completed significant R&D work in project management and project scheduling for aircraft periodical maintenance management in a past project (Hao et al. 2009a; 2009b).
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Towards a hierarchical modelling approach for planning aircraft tail assignment and predictive maintenance

Towards a hierarchical modelling approach for planning aircraft tail assignment and predictive maintenance

Introduction Aircraft connectivity plays a promising role in operation cost reduction for airlines. Thanks to data collection of maintain- able systems some equipment can be monitored, and un- scheduled maintenance can be triggered by the evolution of the related health indicator (Wang, Chu, and Wu 2007). Note the visibility of upcoming failures can help to redefine the maintenance planning and reduce Aircraft On Ground (AOG) risk. In this context, predictive maintenance (Mobley 2002) aims to consider the real time values of health indica- tors, as well as their likely evolution, to plan unscheduled maintenance. However, specific aircraft routing is necessary to be able to perform maintenance in some cases. Thus, a planning model that controls routing allocation and mainte- nance actions could efficiently reduce operation costs.
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Antisubordination Planning

Antisubordination Planning

20 To understand justice and what it requires of us, we must understand how systemic unjust advantage is continuously reproduced (Connolly and Steil 2009). Planning has played a central role in the creation of racial disparities, from explicit zoning based on race to support for racial covenants and discriminatory lending, from urban renewal to contemporary gentrification and displacement. But urban planning has not taken a clear stand to address these racial disparities, or even to systematically recognize the role of planning in the white supremacist construction of U.S. urban and suburban space. As Mills (2003), has emphasized, white supremacist social and economic structures are upheld not by “claims to knowledge so much as claims to ignorance—a nonknowing that is not the innocent unawareness of truths to which there is no access, but a self and social shielding from racial realities that is underwritten by the official social epistemology” (190). Indeed, a recognition and effort to address these disparities is fundamental to the health of democracy. The “core citizenly responsibility is to prove oneself trustworthy to fellow citizens,” Danielle Allen (2004) has written, and “in order to prove oneself trustworthy, one has to know why one is distrusted” such that the “the politics of friendship requires of citizens a capacity to attend to the dark side of the democratic soul” (10).
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A cost driven predictive maintenance policy for structural airframe maintenance

A cost driven predictive maintenance policy for structural airframe maintenance

Abstract Airframe maintenance is traditionally performed at scheduled maintenance stops. The decision to repair a fuselage panel is based on a fixed crack size threshold, which allows to ensure the aircraft safety until the next scheduled maintenance stop. With progress in sensor technology and data processing techniques, structural health monitoring (SHM) systems are increasingly being considered in the aviation industry. SHM systems track the aircraft health state continuously, lead- ing to the possibility of planning maintenance based on an actual state of aircraft rather than on a fixed schedule. This paper builds upon a model-based prognostics framework that the authors developed in their previous work, which couples the Extended Kalman filter (EKF) with a first- order perturbation (FOP) method. By using the information given by this prognostics method, a novel cost driven predictive maintenance (CDPM) policy is proposed, which ensures the aircraft safety while minimizing the maintenance cost. The proposed policy is formally derived based on the trade-off between probabilities of occurrence of scheduled and unscheduled maintenance. A numerical case study simulating the maintenance process of an entire fleet of aircrafts is imple- mented. Under the condition of assuring the same safety level, the CDPM is compared in terms of cost with two other maintenance policies: scheduled maintenance and threshold based SHM maintenance. The comparison results show CDPM could lead to significant cost savings.
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