摘要:

The expected profit is frequently used as an optimality criterion in manufacturing and maintenance operations. In this paper, we consider the optimal preventive maintenance policy and the optimal repair limit policy which maximize the expected earning rates for one-unit systems subject to failure and repair, respectively. In particular, the total time on test concept is used to directly estimate the optimal policies from empirical sample data. The proposed methods provide geometrical interpretations of the underlying probabilistic problems to practitioners as well as nonparametric estimators of the optimal maintenance strategies.

ISSN:0740-817X    

DOI:10.1080/07408179808966566

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper investigates the maintenance decision situation in which three actions, minimal repair, periodic overhaul and complete renewal, may be applied to the system under consideration. A new mathematical model is proposed to describe system improvement due to the maintenance action of an overhaul that differs from the virtual age approach by considering a direct reduction on the system's failure rate. Based on this improvement model, two cost models for determining the optimal overhaul interval and the number of overhauls in a renewal cycle, that minimize the expected unit-time cost or the total discounted cost, are established. Existence conditions of optimal solutions are obtained and special cases of the two cost models are discussed.

ISSN:0740-817X    

DOI:10.1080/07408179808966567

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

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 intondiscrete 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.

ISSN:0740-817X    

DOI:10.1080/07408179808966568

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Weapon systems that function destructively (e.g., missile or torpedo) are to be acquired in a lot of sizem. Acceptance of the lot is based on the result of an operational test, administered to part of the lot: if the test results indicate positive operational value the lot is accepted and the remaining part of the lot is fielded; otherwise the lot is “rejected”. A test plan is designed that establishes an optimal number of weapon copies to test, given models of the operational gain of the fielded weapon under two tactical options, and the uncertainty in the weapon's predicted probability of success after the test is complete. The major test objective is to realize possible operational utility from the lot of items, and secondarily to demonstrate arbitrary levels of certainty.

ISSN:0740-817X    

DOI:10.1080/07408179808966569

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this paper, a software cost model with a warranty period and cost, a cost to remove each error detected in the software and a risk cost due to software failure is developed. A software reliability model based on the nonhomogeneous Poisson process is used. The optimal release policies which minimize the expected total software costs are presented. A software tool is also developed using Excel and Visual Basic that facilitates the task of determining the optimal software release time. Numerical examples are provided to illustrate the results.

ISSN:0740-817X    

DOI:10.1080/07408179808966570

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In the development of new electronic systems the planning of reliability growth tests has become both more critical and more difficult as available testing budgets have diminished. Previously, system designers were able to plan and implement relatively lengthy reliability growth test plans to assist in the development of reliable systems. A new method is presented to allocate subsystem reliability growth test time in order to maximize the system mean time between failure (MTBF) or system reliability when designers are confronted with limited testing resources. For certain problems, the algorithm yields the same results as competing approaches to the problem but with significantly fewer required iterations. More significantly, the new algorithm applies to a larger problem domain compared to analogous algorithms. Much more realistic formulations of the problem can now be solved optimally. The algorithm is based on objective function gradient information projected onto a feasible region that consists of candidate test plans given the testing budget constraint. The algorithm is demonstrated on several examples with superior results.

ISSN:0740-817X    

DOI:10.1080/07408179808966571

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In 1995 a record 17.8 million vehicles were recalled in the USA. In addition to these recalls, warranty costs for non-recallable defects, and the cost of lost future sales due to dissatisfied customers, contribute to the cost associated with poor quality. Although pre-production testing has more leverage, post-launch vehicle testing may provide valuable information in an economical fashion. By field testing the first production vehicles off the line, automotive manufacturers may detect manufacturing-related and component-interaction defects that would not be discovered by pre-production testing. We present acost-benefitmodel for production vehicle field testing. Using data on defects and warranty costs for past vehicle programs, we can estimate the average warranty cost, the likelihood of a recall, the number of vehicles recalled, failure rates, and severity of defects for future vehicle programs, as well as the warranty costs avoided by a particular production vehicle test program. This cost-benefit analysis allows us to determine if a post-production vehicle test program is worthwhile, and if so, it allows us to choose the best such program.

ISSN:0740-817X    

DOI:10.1080/07408179808966572

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper describes a general approach to the optimal design of communications networks when considering both economics and reliability. The approach uses a genetic algorithm to identify the best topology of network arcs to collectively meet cost and network reliability considerations. This approach is distinct because it is highly flexible and can readily solve many versions of the network design problem, including formulations not previously seen in the literature that more closely reflect actual design scenarios. The method is shown to be effective, computationally efficient and flexible on a suite of diverse test problems.

ISSN:0740-817X    

DOI:10.1080/07408179808966573

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Many real-world systems such as transportation systems and manufacturing systems can be regarded as flow networks whose arcs have independent, finite and multi-valued random capacities. Such a flow network is indeed a multistate system with multistate components and so its reliability for level (d,c), i.e., the probability thatdunits of flow can be transmitted from the source node to the sink node such that the total transmission cost is less than or equal toc, can be computed in terms of minimal path vectors to level (d,c) (named (d,c)-MPs here). The main objective of this paper is to present a simple algorithm to generate all (d,c)-MPs of such a system for each level (d,c) in terms of minimal pathsets. Two examples are given to illustrate how all (d,c)-MPs are generated by our algorithm and then the reliability of one example is computed.

ISSN:0740-817X    

DOI:10.1080/07408179808966574

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We deal with a system whose failures depend on several parallel effects, such as the time in use ℒ and the mileage ℋ. Manufacturer warranties are typically described by a two-dimensional region in the (ℒ, ℋ)-plane. A proper determination of the warranty limits must be based on a two-dimensional distribution of time to failure on this plane. The aim of this paper is to demonstrate the possibility of designing individual warranties for a “nontypical” customer who has a very low or very high usage rateb=H/L, and to show a simple way to calculate warranty limits by minimizing the lifetime coefficient of variation. The latter is carried out by introducing the “best” combined time scale in the form 𝒦 = (1−ϵ)ℒ+ϵℋ which provides the minimal lifetime coefficient of variation.

ISSN:0740-817X    

DOI:10.1080/07408179808966575

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor