Search results

To provide a brief introduction to warranty analysis and a classification of general repairs. To introduce the notion of accelerated probability distribution and use it to model imperfect warranty repairs.

The notion of accelerated probability distribution is discussed and its similarity with quasi‐renewal and geometric processes is observed. An approach to modeling imperfect warranty repairs based on the accelerated probability distributions is presented, and the corresponding expected warranty cost over the warranty period under non‐renewing free replacement warranty policy is evaluated.

It is observed that quasi‐renewal and the geometric processes are equivalent. Using data from an existing warranty database it is shown that the inter‐repair times form a quasi‐renewal process. The corresponding expected warranty cost over the warranty period under a non‐renewing free replacement warranty policy is evaluated.

This approach is applicable only if the cost of the warranty repair is an increasing function of the number of repairs.

Provides a useful approach to modeling inter‐repair times incorporating the idea of imperfect repairs in practice.

Provides an approach to model imperfect warranty repairs and to evaluate the corresponding expected warranty cost.

The purpose of this paper is to study a geometric process (GP) maintenance model and policy for a repairable system.

Lam first introduced the GP and its application to maintenance model. Assume that a replacement policy N is applied by which the system will be replaced by a new, identical one following the Nth failure.

For a deteriorating system, an optimal replacement policy is determined analytically, and the monotonicity properties of the optimal replacement policy are then studied.

For an improving system, the paper shows that the optimal replacement policy is the ∞ policy, i.e., the policy without replacement.

This paper aims to present a method for calculating the top event probability of a fault tree with priority AND gates.

The paper makes use of Merle's temporal operators for obtaining the minimal cut sequence set of a dynamic fault tree. Although Merle's expression is based on the occurrence time of an event sequence, the paper treats the expression as an event containing the order of events. This enables the authors to treat the minimal cut sequence set by using the static fault tree techniques. The proposed method is based on the sum of disjoint products. The method for a static FT is extended to a more applicable one that can deal with the order operators proposed by Merle et al.

First, an algorithm to obtain the minimal cut sequence set of dynamic fault trees is proposed. This algorithm enables the authors to analyze reasonably large scale dynamic fault trees. Second, the proposed method of obtaining the top event probability of a dynamic fault tree is efficient compared with an inclusion‐exclusion based method proposed by Merle et al. and a conventional Markov chain approach. Furthermore, the paper shows the top event probability is derived easily when all the basic events have exponential failure rates.

The methodology presented shows a new solution for calculating the top event probability of dynamic fault trees.

The purpose of this paper is to consider maintenance policies for an operating system which works at random times for jobs. Each job causes some damage to the system and these damages are additive, and the system fails when the total damage has exceeded a failure level K.

Using techniques of cumulative damage models, the maintenance is made at the N‐th completion of working time for the first model and at a damage level Z with a limit number of working times N for the second model.

The system is maintained at the first completion of the working time over time T for the third model. The system fails with probability p(x) when the total damage is x and undergoes minimal repair at failure for the fourth model. The expected cost rates are obtained and optimal maintenance policies are discussed analytically and computed numerically.

The paper discusses four maintenance policies for an operating system which works at successive random times for jobs, where the system fails due to damage that can be additive caused by jobs.

To provide a brief survey of the literature directed towards the analysis of warranty claim data.

For convenience, this survey of the analysis of warranty claims data is somewhat arbitrarily be classified by topics as follows: age‐based claims analysis, aggregated warranty claims analysis, marginal counts of claims analysis, warranty claims analysis by using covariates, estimation of lifetime distribution using supplementary data, two‐dimensional warranty, warranty costs analysis, sales lag and reporting lag analysis, and forecasts of warranty claims.

Emphasis is placed on a discussion of different kinds of warranty claims data selected from reviews and on a comparison of the statistical models and methods used to analyze such data.

Since the literature on product warranty data is vast, more work on this problem is needed.

This review points out why warranty claims data is important and gives a survey of the literature pertaining to the analysis of such data. The emphasis is on the analysis of minimal databases of real warranty data, constructed by combining information from different sources, which can be collected economically and efficiently through service networks. The research is applicable for those responsible for product reliability, product design decisions and warranty management in manufacturing industries.

The paper reviews different statistical models and methods used to analyze warranty claims data. The statistical models and methods presented are be valuable and meaningful tools for product reliability and warranty management and analysis.

To consider the problem of outsourcing warranty repairs to outside vendors when items have priorities in service.

The repair allocation problem is formulated as a convex minimum‐cost network flow problem and solve it by the successive shortest path algorithm. The computation issues involved with the problem are also discussed.

Examples are provided to illustrate the cost benefits achieved due to the priority structure.

The research uses a closed static allocation model. Future research efforts can expand our model by considering a dynamic allocation method or an open population model.

The paper can be a valuable resource to warranty managers who make decisions regarding the negotiations of warranty contracts and the allocation of items to outside repair vendors.

A warranty manager can apply our results to receive insight on the value of giving priority in service to special customers. In addition, resource allocation problems with an objective structure similar to our application can be efficiently solved using our algorithm.

The purpose of this paper is to study the life cycle cost (LCC) on the operation of power generation. LCC is the total cost of ownership including the cost of the project or asset acquisition, operation and maintenance, and disposal. LCC includes both deterministic costs (such as acquisition costs, improvement costs and disposal costs) and probabilistic (such as the costs of failure, repairs, spare parts, downtime, lost gross margin). Most of the probabilistic costs are associated directly with the reliability and maintenance characteristics of the system.

To be able to analyze failure data using appropriate cost profile in order to represent the fact that each failure has different prices, in different time periods at an economical cycle the new methodology of LCCA Diagram is proposed. Developing criticality ranking of sub‐system, calculating values of Weibull Shape Factor β and Weibull Characteristic Life η for each sub‐system, calculating the time to failure of sub‐system, calculating the mean time to failure of sub‐system using Monte Carlo simulation, determining several alternatives, failure mode and effects analysis and root cause failure analysis are parts of the methodology.

To give a sample of case study, the LCC on the operation of coal fired power plant (CFPP) 330 MW is analyzed. Five alternatives calculation of LCC will be simulated. Graph of cash flow, break‐even graph, and graph of cost/benefit versus risk made for a period of 30 years can be used to asses an effective management program and costs of power plant with a low risk.

The paper suggests that LCC can be used to asses an effective management program and costs of power plant with a low risk.

The purpose of this paper is to evaluate and analyse the production and maintenance performance of a manual and a semi‐automatic load haul dump (LHD) machine to find similarities and differences.

Real time process‐, operational‐ and maintenance data, from an underground mine in Sweden, have been refined and aggregated into KPIs in order to make the comparison between the LHDs.

The main finding is the demonstration of how production and maintenance data can be improved through information fusion, showing some unexpected results for maintenance of automatic and semi‐automatic LHDs in the mining industry. It was found that up to one third of the manually entered workshop data are not consistent with the automatically recorded production times. It is found that there are similarities in utilization and filling rate but differences in produced tonnes/machine hour between the two machines.

The originality in this paper is the information fusion between automatically produced production data and maintenance data which increases the accuracy of reliability analysis data. Combining the production indicator and the maintenance indicator gives a common tool to the production and maintenance departments. This paper shows the difference in both maintenance and production performance between a manual and semi‐automatic LHD.

To make a theoretical comparison between two scale‐inspection and warranty policies for weight‐quality, one practical and the other theoretically grounded.

Comparison is made in a Stackelberg game framework considering the consumer's as well as the manufacturer's viewpoint.

The practical policy is more profitable for the manufacturer than the theoretical policy in many cases.

The study confines itself to scale‐inspection and warranty policies, but the underlying approach used in this paper can also be applied to other topics.

The proposed model can also provide a lower bound for the warranty.

The study compares a practical policy with a theoretical one from both the consumer's and manufacturer's point of view.