Showing papers on "Preventive maintenance published in 1998"
TL;DR: In this article, a probabilistic model is proposed for the purpose of maintenance, and a computer program based on this model is described, providing a quantitative connection between reliability and maintenance, a link missing in the heuristic approaches.
Abstract: The purpose of maintenance is to extend equipment lifetime, or at least the mean time to the next failure. While too little maintenance may have very costly consequences, maintenance, too, incurs expenditures and it may not be economical to perform it too frequently. Therefore, the two costs must be balanced. In the past, attempts to approximate this balance have often been based on trial and error. In this paper, a probabilistic model is proposed for the purpose, and a computer program based on this model is described. The model provides a quantitative connection between reliability and maintenance, a link missing in the heuristic approaches. The component ageing process is modelled, and the mean and distribution of the remaining life to failure are predicted for any stage of ageing. The method is applied to a practical example.
227 citations
TL;DR: An analytical model of a software system which serves transactions is presented and expressions for resulting steady state availability, probability that an arriving transaction is lost and an upper bound on the expected response time of a transition are derived.
Abstract: Preventive maintenance of operational software systems, a novel technique for software fault tolerance, is used specifically to counteract the phenomenon of software "aging". However, it incurs some overhead. The necessity to do preventive maintenance, not only in general purpose software systems of mass use, but also in safety-critical and highly available systems, clearly indicates the need to follow an analysis based approach to determine the optimal times to perform preventive maintenance. In this paper, we present an analytical model of a software system which serves transactions. Due to aging, not only the service rate of the software decreases with time, but also the software itself experiences crash/hang failures which result in its unavailability. Two policies for preventive maintenance are modeled and expressions for resulting steady state availability, probability that an arriving transaction is lost and an upper bound on the expected response time of a transition are derived. Numerical examples are presented to illustrate the applicability of the models.
214 citations
Book•
03 Nov 1998
TL;DR: This text is the second edition of the book, which has four new chapters added and three chapters are revised substantially to reflect development in maintenance since the publication of the first edition.
Abstract: Analyzing maintenance as an integrated system with objectives, strategies and processes that need to be planned, designed, engineered, and controlled using statistical and optimization techniques, the theme of this book is the strategic holistic system approach for maintenance. This approach enables maintenance decision makers to view maintenance as a provider of a competitive edge not a necessary evil. Encompassing maintenance systems; maintenance strategic and capacity planning, planned and preventive maintenance, work measurements and standards, material (spares) control, maintenance operations and control, planning and scheduling, maintenance quality, training, and others, this book gives readers an understanding of the relevant methodology and how to apply it to real-world problems in industry. Each chapter includes a number exercises and is suitable as a textbook or a reference for a professionals and practitioners whilst being of interest to industrial engineering, mechanical engineering, electrical engineering, and industrial management students. It can also be used as a textbook for short courses on maintenance in industry. This text is the second edition of the book, which has four new chapters added and three chapters are revised substantially to reflect development in maintenance since the publication of the first edition. The new chapters cover reliability centered maintenance, total productive maintenance, e-maintenance and maintenance performance, productivity and continuous improvement
121 citations
TL;DR: In this article, the authors present a method for predicting a cost-optimal preventive maintenance policy for a repairable system with an increasing Rate of Occurrence Of Failure (ROCOF).
Abstract: In this paper, we present a method for predicting a cost-optimal preventive maintenance policy for a repairable system with an increasing Rate of Occurrence Of Failure (ROCOF). We segment the maintenance planning horizon into n discrete and equally-sized periods. For each period, we predict which of three possible actions, (maintain the system, replace the system, or do nothing to the system) should be taken, such that the total net present worth of all future costs is minimized. Our model expands upon previous work by utilizing the concept that maintenance reduces the “effective age” of the system and hence the system ROCOF. We develop the model and evaluate three solution procedures, namely, a random search, a genetic algorithm, and a branch-and-bound approach. The entire approach is illustrated through the use of a numerical example.
83 citations
TL;DR: An optimization model is formulated to minimize unit time system life cycle cost subject to reliability requirements to obtain optimal values of system design, burn-in period, preventive maintenance intervals and replacement time.
67 citations
TL;DR: The proposed model reduces the shift rate of the system to the out-of-control state proportional to the PM level, and determines the EPQ, the optimal design of the control chart and the optimal preventive maintenance level.
Abstract: In this paper, we investigate the effect of various preventive maintenance policies on the joint optimisation of the economic production quantity (EPQ) and the economic design of control chart. This has been done for a deteriorating process where the in-control period follows a general probability distribution with increasing hazard rate. In the proposed model, preventive maintenance (PM) activities reduce the shift rate of the system to the out-of-control state proportional to the PM level. For each policy, the model determines the EPQ, the optimal design of the control chart and the optimal preventive maintenance level. The effects of the three PM policies on EPQ and quality costs are illustrated using an example of a Weibull shock model with an increasing hazard rate.
66 citations
16 Mar 1998
TL;DR: This research paper presents the results of a field survey for the characterisation of Software Maintenance Process in Portugal, concluded that the three biggest problems related to the Software maintenance process are:The lack of software maintenance process models, the lack of documentation of applications and the lack-of-time to satisfy the requests.
Abstract: This research paper presents the results of a field survey for the characterisation of Software Maintenance Process in Portugal. It was concluded that the three biggest problems related to the Software Maintenance Process are: the lack of software maintenance process models, the lack of documentation of applications and the lack of time to satisfy the requests. Only 2.7% of the people who answered the questionnaire consider the software maintenance process very efficient; 70.2% consider it of a very low level of efficiency.
63 citations
TL;DR: The proposed method is aiming at functionally robust designs, reduction of preventive maintenance cost and more effective fault diagnosis, in terms of inspection, monitoring, diagnosis and planning, based on functional, behavioural and state models.
44 citations
Book•
01 Jan 1998
TL;DR: In this article, the authors present a model for estimating long-term average-cost models for a set of different types of extended and non-extended warranty policies, based on the failure process.
Abstract: 1 Introduction.- 1.1 Warranty.- 1.1.1 Warranty Content.- 1.1.2 Warranty Duration.- 1.1.3 Warranty Type.- 1.1.4 Extended Warranties.- 1.1.5 Quality and Warranty.- 1.2 Preventive Maintenance.- 1.2.1 Rectification Modes.- 1.2.2 Rectification Period and Maintenance Cycle.- 1.2.3 Replacement Strategies.- 1.2.4 Quality and Preventive Maintenance.- 1.3 Objectives, Scope and Summary.- 1.3.1 Unit Warranties.- 1.3.2 Perpetual Warranties.- 1.3.3 Extended Warranties.- 1.3.4 Preventive Maintenance.- 1.4 Notation.- 2 Reliability and Quality Measures.- 2.1 The Failure Process.- 2.1.1 Integral Equation of the Process.- 2.1.2 Recurrence Times.- 2.1.3 Replacement on Failure.- 2.1.4 Minimal Repair.- 2.1.5 Imperfect Repair.- 2.2 Measuring Quality Improvement.- 2.2.1 Mean-and-Variance Ordering.- 2.2.2 Stochastic Ordering.- 2.2.3 Other Partial Ordering Relations.- 2.2.4 Mixture Models.- 2.2.5 Examples.- 3 Unit Warranties.- 3.1 Free-Rectification Warranties.- 3.1.1 Distribution of Warranty Cost.- 3.1.2 Optimal Rectification Effort.- 3.1.3 Impact of Quality.- 3.2 Pro-Rata Replacement Warranties.- 3.2.1 Variables of Interest.- 3.2.2 Examples.- 3.3 Combination Warranties and Warranty Policy.- 3.3.1 Probability Distributions.- 3.3.2 Warranty Policy Design.- 4 Perpetual Warranties.- 4.1 Long-Life-Cycle, Free-Rectification Warranties.- 4.1.1 Cost Rates.- 4.1.2 Impact of Product Quality.- 4.2 Free-Rectification Warranties in Finite Time.- 4.2.1 User's Replacement Cost.- 4.2.2 Manufacturer's Costs and Profit.- 4.2.3 Examples.- 4.3 Long-Life-Cycle, Pro-Rata Warranties.- 4.3.1 Cost Rates.- 4.3.2 Impact of Product Quality.- 4.4 Pro-Rata Warranties in Finite Time.- 4.4.1 Manufacturer's Supply Cost.- 4.4.2 Joint Distribution of BUf(t) and N(t).- 4.4.3 User's Replacement Cost.- 4.4.4 Manufacturer's Warranty Cost.- 4.4.5 Examples.- 5 Extended Warranties.- 5.1 Mathematical Model.- 5.1.1 Probability Distributions.- 5.2 Performance Measures.- 5.2.1 Profitability and Risk-of-Loss.- 5.2.2 Expected Cost and Profit.- 5.2.3 Expected Cost Per Unit Time.- 5.2.4 Multiple Extended Warranty Options.- 5.2.5 User's Perspective.- 5.3 Extensions.- 5.3.1 Extended Warranties for Used Systems.- 5.3.2 Free-Rectification Base Warranty.- 5.3.3 Random Repair.- 5.3.4 Adverse Selection and Moral Hazard.- 6 Preventive Maintenance.- 6.1 Long-Term-Average-Cost Models.- 6.1.1 Age-Replacement Strategy.- 6.1.2 Periodic-Replacement Strategy.- 6.1.3 Repair-Limit Strategy.- 6.2 Quality and Preventive Maintenance.- 6.2.1 Sufficient Conditions for Cost Reduction.- 6.2.2 Extent of Cost Reduction.- 6.3 Cost Models in Finite Time.- 6.3.1 Age-Replacement Strategy.- 6.3.2 Periodic-Replacement Strategy.- 6.3.3 Repair-limit Strategy.- 6.4 Maintenance After Warranty.- 6.4.1 Unit Contracts.- 6.4.2 Perpetual Contracts.
41 citations
TL;DR: In this article, the flexible Kanban system (FKS) is proposed to dynamically and systematically manipulate the number of Kanbans in order to offset the blocking and starvation caused by the said factors during a production cycle.
Abstract: The just-in-time (JIT) system is designed to operate in an ideal environment such as with constant processing times, smooth and stable demand and uninterrupted processing. However, in a real-life environment, the JIT system is subjected to various uncertain factors including stochastic processing times, variable demand and process interruption due to planned preventive maintenance. These factors seriously compromise the performance of JIT. In this paper, we present a newly developed JIT system which uses an algorithm to dynamically and systematically manipulate the number of Kanbans in order to offset the blocking and starvation caused by the said factors during a production cycle. We refer to the new system as the flexible Kanban system (FKS). We provide steps of the algorithm and demonstrate the effectiveness of FKS using a case example. For the case example, we present the solution procedure, results and discussion.
40 citations
TL;DR: In this article, a hybrid Petri net model with parameter trend and fault tree analysis is used to perform early failure detection and isolation for district heating and cooling facilities, and a fault diagnosis system is employed as an example to demonstrate the proposed method.
Abstract: SUMMARY To improve preventive maintenance, this study uses a hybrid Petri net modelling method coupled with parameter trend and fault tree analysis to perform early failure detection and isolation. A Petri net arrangement is proposed that facilitates alarm, early failure detection, fault isolation, event count, system state description and automatic shutdown or regulation. These functions are very useful for health monitoring and preventive maintenance of a system. A fault diagnosis system for district heating and cooling facilities is employed as an example to demonstrate the proposed method. ©1998 John Wiley & Sons, Ltd.
TL;DR: In this article, the optimal number of preventive maintenance activities to be scheduled within a time horizon of interest, the required extent of the preventive maintenance by means of an age reduction of the unit and the corresponding optimal value of the expected profit were determined.
TL;DR: In this article, the authors propose to decompose the global generator/transmission scheduling problem into a master problem and sub-problems using Benders decomposition to minimize operation costs while satisfying the network constraints.
01 Jan 1998
20 Sep 1998
TL;DR: In this paper, the maintenance of the optical distribution network in PONs is discussed, where post-fault maintenance (to detect, locate and restore the faults) and preventive maintenance are both considered.
Abstract: The maintenance of the ODN (optical distribution network) in PONs is discussed. Post-fault maintenance (to detect, locate and restore the faults) and preventive maintenance (to reduce the fault events) are both considered. The use of OTDR based measuring and monitoring systems is examined in detail.
TL;DR: The optimal ordering policies minimizing the long-run average cost are analytically derived and referred to in the mathematical contexts of the order-replacement problems and their applications.
Abstract: In this paper, we consider a typical but somewhat generalized order-replacement model arising in the spare part inventory management. The optimal ordering policies minimizing the long-run average cost are analytically derived. We review the mathematical contexts of the order-replacement problems and refer to their applications. A comprehensive bibliography in this research area is provided.
TL;DR: A delay–time model is developed and applied to model and optimize preventive maintenance (PM) of a plant manufacturing brake linings and a key subsystem in the plant is used to illustrate the modelling process and management reaction.
Abstract: This paper presents a maintenance-modelling case study of a plant manufacturing brake linings. A delay–time model is developed and applied to model and optimize preventive maintenance (PM). A key subsystem in the plant is used to illustrate the modelling process and management reaction. Defects identified at PM may not all be removed. This incomplete response to PM is a feature which has not been modelled before. The parameter values of the delay-time process are estimated from objective data from maintenance records of failures, using the method of maximum likelihood. This is aided by a theorem extending results on the NHPP arival rate of failures in a perfect-inspection case to the non-perfect-inspection case. Problems of parameter estimation given inadequate data collected at PMs are discussed, and the necessity to augment objective data with subjective assessments highlighted. Based upon the estimated model parameters and delay-time distribution, an inspection model is constructed to describe the relationship between the total unit downtime and the PM interval. The response of management is discussed.
TL;DR: A subjective data based case study carried out at a company manufacturing copper products, which parallels a previously published objective data based study at the same plant, to model the implementation of Planned Preventive Maintenance to an Extrusion Press using the delay time concept.
Abstract: In this paper we describe a subjective data based case study carried out at a company manufacturing copper products, which parallels a previously published objective data based study at the same plant. The purpose of this study is twofold. The first is to model the implementation of Planned Preventive Maintenance (PM) to an Extrusion Press using the delay time concept. The second is to test a method for estimation of model parameters from subjective data in the context of delay time modelling. The parameter values of the underlying fault arrival process and the delay time distribution were, unlike in a parallel objective study, initially estimated from subjective data obtained through a questionnaire survey. Since bias was present in the initial subjective estimate, a method of removing it was developed to improve the model fit. On the basis of the data analysis and delay time modelling, improved PM policy and procedures were proposed to increase the effectiveness and efficiency of PM.
07 Sep 1998
TL;DR: An approach to on-board preventive maintenance which rejuvenates a system via periodical duty switching between system components, slowing down a system's aging process and enhancing mission reliability is presented.
Abstract: The long-life deep-space missions associated with NASA's X2000 Advanced Flight Systems Program creates many unprecedented challenges. In particular the stringent constraints on the mass of a spacecraft and the power on-board preclude traditional fault tolerance approaches which rely on extensive component/subsystem replication, calling for novel approaches to mission reliability enhancement. In this paper we present an approach to on-board preventive maintenance which rejuvenates a system via periodical duty switching between system components, slowing down a system's aging process and enhancing mission reliability. By exploiting the nondedicated system redundancy hardware and software rejuvenation are realized simultaneously without significant performance penalty. Our model-based evaluation confirms a potential for significant gains in mission reliability from on-board preventive maintenance and provides to us useful insights about the collective effect of age-dependent failure behavior residual mission life, risk of unsuccessful maintenance and maintenance frequency on mission reliability.
26 Oct 1998
TL;DR: It is shown how maintenance scheduling can be cast as a constraint satisfaction problem and used to define the structure of randomly generated non-binary CSPs, and several previously studied backtracking-based algorithms are evaluated.
Abstract: A well-studied problem in the electric power industry is that of optimally scheduling preventative maintenance of power generating units within a power plant [1, 3]. The general purpose of determining a maintenance schedule is to determine the duration and sequence of outages of power generating units over a given time period, while minimizing operating and maintenance costs over the planning period, subject to various constraints. We show how maintenance scheduling can be cast as a constraint satisfaction problem and used to define the structure of randomly generated non-binary CSPs. These random problem instances are then used to evaluate several previously studied backtracking-based algorithms, including backjumping and dynamic variable ordering augmented with constraint learning and look-ahead value ordering [2].
TL;DR: An efficient algorithm is developed to demonstrate the optimal strategy for a queue-like production system, via numerical results that offer useful insights, and the actual starting time of preventive maintenance is modelled in terms of a uniform distribution over the maintenance interval.
TL;DR: In this paper, the authors stress the importance of utilizing the knowledge of maintenance engineers, i.e., expert judgment, in addition to recorded equipment lifelengths, in order to get credible input data.
TL;DR: In this article, a model description for the influence of preventive maintenance on protection system reliability performance is presented, where the model description is constructed as a continuous time Markov chain and the system states and the transitions between states are generated in a general and systematic manner.
Abstract: Protection systems exhibit two important types of failures: failures to operate and unwanted operations. Both failure modes have been introduced in a model description designed for the evaluation of the influence of preventive maintenance on protection system reliability performance. The model description is constructed as a continuous time Markov chain. The system states and the transitions between states are generated in a general and systematic manner which makes it possible to apply the model description to a lot of different situations. Through an example it is shown that (the quality) of preventive maintenance can have significant influence upon the reliability performance of a given system.
TL;DR: The Michigan Department of Transportation is committed to the successful implementation of a preventive maintenance program to protect pavement and bridge structures, slow the rate of deterioration, and correct minor pavement deficiencies using surface treatments that primarily target pavement surface defects caused by the environment and deficiencies in pavement materials.
Abstract: The Michigan Department of Transportation is committed to the successful implementation of a preventive maintenance program to protect pavement and bridge structures, slow the rate of deterioration, and correct minor pavement deficiencies using surface treatments that primarily target pavement surface defects caused by the environment and deficiencies in pavement materials. Structural deficiencies of the pavement structure caused by traffic-loading are generally not corrected by this program. Many innovative concepts were incorporated in the Michigan Preventive Maintenance Program. The business processes were simplified, and more responsibility was given to the private sector. All preventive maintenance projects used standard specifications and contained a limited number of pay items. But perhaps the most substantial concept was the introduction of warranty specifications for all surface treatments. The implementation of warranty specifications involved mutual trust and cooperation between the department ...
01 Dec 1998
TL;DR: Parameters of the production system, in particular the allowable in-process buffers, and the design parameters of the maintenance plan are considered simultaneously as integral parts of the whole decision process for selection and implementation of a maintenance policy.
Abstract: Selecting an optimum maintenance policy independent of other parameters of the production system does not always yield the overall optimum operating conditions. For instance, high levels of in-process inventories affect the performance of a given maintenance policy by reducing the effects of machine breakdowns. In this study, parameters of the production system, in particular the allowable in-process buffers, and the design parameters of the maintenance plan are considered simultaneously as integral parts of the whole decision process for selection and implementation of a maintenance policy. The results from the simulation experiments show that the response surfaces for these systems are of the forms that yield themselves to an optimization search. However, the optimization problem itself is not trivial, as the performance of the system depends on a combination of qualitative and policy variables (the choice of the maintenance policy) as well as a set of quantitative variables (allowable buffer spaces). In this paper, a methodology is presented for solving this class of problems that is based on a combined computer simulation and optimization integrated with a genetic algorithm search.
TL;DR: The paper attempts to provide a unified approach to manage maintenance and thus reduce risks to an acceptable level and the role of maintenance planning to achieve this objective.
Abstract: The effective management of risk is the characteristic feature of a successful organization. The risk may be relating to safety, the environment, or one affecting profitability. This paper discusses failures and the mechanism by which they escalate into serious incidents. A generalized model is used to illustrate the method by which such escalation may be prevented. A hypothesis is then postulated to relate the frequency of serious events, minor failures and the availability of protective barriers. The methods that can be used to optimize the barrier avilability are then explored. A practical way to compute the test intervals in order to obtain the required barrier availability is suggested. The role of maintenance planning to achieve this objective is discussed briefly. The paper attempts to provide a unified approach to manage maintenance and thus reduce risks to an acceptable level.
19 Jan 1998
TL;DR: In this paper, the authors characterize the solution to a general class of preventive maintenance optimization problems, where the equipment is subjected to an age replacement preventive maintenance policy and the successive preventive maintenance times are assumed to be i.i.d. Weibull random variables.
Abstract: The intention of the effort presented is to characterize the solution to a general class of preventive maintenance optimization problems. Successive lengths of operating periods and the successive repair times for a piece of equipment are each assumed to be i.i.d. Weibull random variables. The equipment is subjected to an age replacement preventive maintenance policy and the successive preventive maintenance times are assumed to be i.i.d. Weibull random variables. An optimal age replacement policy is a policy, T/sub age/*, that maximizes A/sub avg/(T/sub use/), the average availability of the equipment over its useful life (T/sub use/
26 Mar 1998
TL;DR: This paper separates on-board maintenance into three categories: preventive maintenance, perfective maintenance and corrective maintenance, and presents its definition and proposes some approaches to its realization.
Abstract: Due to the low power, low cost, high reliability and high performance goals, the traditional approaches to fault-tolerant, ultra-reliable systems that rely on custom-built hardware and extensive component/subsystem replication will not be feasible for the new-generation spaceborne computing systems. In this paper, we present a new concept called "on-board maintenance". We classify on-board maintenance into three categories: preventive maintenance, perfective maintenance and corrective maintenance. For each type, we present its definition and propose some approaches to its realization.
TL;DR: In this paper, a rotordynamic model is used to predict the rate of deterioration of a turbine-generator rotor and a simulation is performed to predict either the machine life or the maintenance period.
Abstract: A use of rotordynamic models in predictive maintenance is described in which variables characterizing the state of a deterioration mechanism are determined from online measurements. These variables are trended to determine the rate of deterioration and to perform a simulation to predict either the machine life or the maintenance period. Some useful terms for using models in predictive maintenance are defined and the prediction procedure is described. The procedure is demonstrated with a simple two degree-of-freedom example and the numerical model of an actual hydraulic turbine-generator rotor. Some benefits and problems associated with the implementation of the procedure are then discussed. It is considered that this procedure brings the possibility of a better understanding of deterioration processes and a resulting better life prediction.