Maintenance modelling

We use a two-compartment model in this section. One of the most widely used models for fermentation processes is the maintenance model in which the substrate S consumption rs is expressed in the form... 

Expensive, unpredictable developments Typically late delivery, over budget, and reduced functionality Single platform dependency Often immature and fragile with an undefined maintenance model Drain on expert resources... 

To ameliorate all the aforementioned shortcomings, we developed a new maintenance model based on the use of Monte Carlo simulation. The model incorporates three practical issues that have not been considered in previous work i) different failure modes of equipment, ii) ranking of equipments according to the consequences of failure, iii) labor resource constraints and material resource constraints. The maintenance model, which was developed by Nguyen et al. (2008) is integrated here with a GA optimization to optimize the PM frequency. 

Monte Carlo simulation - based maintenance model... 

The MTBFs for all equipments are obtained from Center for Chemical Process Safety (1989) and the maintenance time is obtained from Bloch and Geitner (2006) (for pumps, compressors, valves) or estimated if the information is not available (for other equipments). Our example shows the results when the PM time intervals are optimized. Other variables are fixed ten employees, keeping inventory for all spare parts and reasonable numbers for the PM starting time. The maintenance model and the GA are implemented in Fortran running on a 2.8 GHz CPU, 1028 MB RAM PC. The final results for the fraction a (PM time interval = o MTBF) are shown in table 3. 

A new maintenance model based on the use of Monte Carlo simulation and integrated with GA optimization is presented in this article. The model incorporates three practical issues not considered in previous work and is capable of analyzing and optimizing complex maintenance operations. 

Internal and external maintenance measures should be described in a Maintenance Plan, which should make use of one or more of the following maintenance models ... 

A number of capabilities should be provided by an integrated and shared MBMS of a DSS (Barbosa and Herko 1980 Liang 1985) construction, model maintenance, model storage, model manipulation, and model access (Applegate et al. 1986). These involve control, flexibility, feedback, interface, redundancy reduction, and increased consistency ... 

There have been a large number of models describing the software maintenance process. Probably the best models are those that have remained in-house and are a hybrid devised from several models and current in-house practice. The published models can be classified into four types. Maintenance models can be classified into four types ... 

Reliability and Safety Data Collection and Analysis Fault Identification and Diagnostics Maintenance Modelling and Optimisation Structural Reliability and Design Codes Software Reliability Consequence Modelling Uncertainty and Sensitivity Analysis Safety Culture Organizational Learning Human Factors... 

The maintenance model proposes carrying out imperfect inspections after the first N — failures and a perfect restoration following the failure. In what follows we aim at obtaining the number of failures, N that minimizes Q T, N). 

We consider a maintenance model of a system subject to cracks, where corrective and preventive maintenances take place according to the following scheme. 

A NEW EFFECTIVE AGE-BASED APPROACH FOR IMPERFECT MAINTENANCE MODELING... 

Through a brief summary of imperfect maintenance modeling resorting to the concept of effective age, this paper highlighted some of the counterintuitive behaviors that can result from models usually referred to in the literature. An approach to adapt these models was proposed, based on the following two observations. 

Though this work proposes an alternative approach to imperfect maintenance models available so far in the literature, it is far from being complete. Indeed, the characterization of e.g. efficiency as a decreasing function with time is the plasticity region needs... 

Clavareau J. Labeau RE. 2008. An alternative imperfect preventive maintenance model. In Safety, Reliability and Risk Analysis Theory, Methods and Applications. Proceedings ofEsrel2008, Valencia (Spain). S. Martorelleta/. (eds),Vol. 1 455-462. 

Wu S. Clements-Croome D. 2005. Preventive maintenance models with random maintenance quality. Reliability Engineering and System Safety. 90 99-105. 

The maintenance model expressed in this work departs from an analysis done to a set of representative previous models, in order to have a new model constituted by the best characteristics observed. The modeling work has involved a research about some basic concepts (business process, modeling, modeling language, business architecture, etc.) to select the most suitable language and software tool for the particular case. 

Riis, J., Luxhoj, J. Thorsteinsson, U. 1997. A situational maintenance model. International Journal of Quality and Reliability Management 14(4) 349-366. 

A key issue in maintenance modeling is the modeling of the processes of component degradation to failure a realistic modeling implies that the impact of the actual living conditions on the component degradation be accounted for. 

First maintenance models were built to manage the maintenance operations of a single component. Then, researches focus on the modelling and optimization of maintenance of multi-component systems (Cho Parlar 1991). 

Cho, D. Parlar, M. 1991. A survey of maintenance models for multi-unit systems. European Journal of Operational Research 51(1) 1 23. 

Nicolai, R. 2008. Maintenance Models for Systems subject to Measurable Deterioration. Ph. D. thesis, Erasmus Universiteit Rotterdam. 

ABSTRACT The aim of this paper is to propose a maintenance model for a deteriorating system. The system considered begins to deteriorate with a slow deterioration rate and at an unknown time the system s deterioration rate changes and the new deterioration rate is a time dependent function. To deal with the change of mode of deterioration in the framework of the maintenance decision rule an adequate on-line change detection algorithm is used. The maintenance decision rule is chosen in order to minimise the global maintenance cost. 

Nicolai, R. (2008). Maintenance models for systems subject to measurable deterioration. P.H.D Erasmus Universiteit Rotterdam. 

In accordance with Castanier et al. (2003), because of this regenerative property, and following a widely used approach in maintenance modeling based on the renewal theorem, the long-run study (i.e. on an infinite time span) of the deterioration process can be limited to the study of the system state evolution on a single renewal cycle defined by the time period between the instant when the system enters the first state and the moment when it undergoes a replacement. 

Different unavailability states of system components (some times they are named basic events ) are modeled by one of the tree following maintenance models ... 

Figure 1. Overall structure for multi-component system maintenance modelling the boxes are the modelling modules, the white arrows represent interactions at the system level, the black arrows represent interactions between system and component levels. System performances are assessed in terms of maintenance cost and availability. 

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