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Technological advancements and growing complexity of many real-time systems, namely, communication, transportation, defense systems, etc., necessitate the importance to adopt a well-planned repair process such as phase type quasi-renewal process contributing to an improved system performance. Further, in an attempt to boost the role of maintenance as a financial benefactor, repairman’s multiple vacation policy is incorporated. Also, the significance of the degree of repair is illustrated while indicating the suitability of the matrix-analytic approach via the phase type quasi-renewal operating/repair times in reliability. The paper aims to discuss these issues.

The optimal replacement policy is obtained by employing the matrix-analytic method and minimum average cost rate.

The considered models make a significant contribution towards establishing that the matrix-analytic method, using the phase type quasi-renewal process, aids in reducing the computations and also fills the gap in the literature in the study of deteriorating systems. Availability and rate of occurrence of failures are evaluated in transient and steady-state regime.

This model differs from the existing models, in that, a repairman’s multiple vacation, delayed repair time and representation of the failure occurrence by a mixed Poisson process have been incorporated into the analysis. Also, time-dependent case and N-policy have been adopted to explore the optimality issues using phase type quasi-renewal process analytically. The numerical illustrations warrant that the maintenance policy proposed in this paper produces a considerably lower cost.

This work examines a repairable machining system’s reliability by considering multiple failure scenarios, including individual component failures, hardware and software malfunctions, failures resulting from shared causes and failures caused by human error. When a system is susceptible to several modes of failure, the primary goal is to forecast availability and other reliability metrics as well as to calculate the expected profit of the repairable machining system.

The process of recovering after a system failure involves inspecting the system and fixing any malfunctions that may have occurred. The repair procedures for all kinds of faults are taken to follow a general distribution to represent real-time circumstances. We develop a non-Markovian stochastic model representing different system states that reveal working, failed, degraded, repair and delayed repair states. Laplace transformation and the supplementary variable technique are used to assess the transient states of the system.

Analytical expressions for system performance indices such as availability, reliability and cost-benefit analysis are derived. The transient probabilities when the system experiences in different states such as failed, degraded and delayed states are computed. The results obtained are validated using Mathematica software by performing a numerical illustration on setting default values of unknown parameters. This ensures the accuracy and reliability indices of the analytical predictions.

By methodically examining the system in its several states, we will be able to spot possible problems and offer efficient fixes for recovery. The system administrators would check to see if a minor or major repair is needed, or if a replacement is occasionally taken into consideration to prevent recurring repairs.

Wind power is an important source of renewable energy and accounts for significant portions in supplying electricity in many countries and locations. The purpose of this paper is to develop a method for wind power system reliability assessment and condition-based maintenance (CBM) optimization considering both turbine and wind uncertainty. Existing studies on wind power system reliability mostly considered wind uncertainty only and did not account for turbine condition prediction.

Wind power system reliability can be defined as the probability that the generated power meets the demand, which is affected by both wind uncertainty and wind turbine failures. In this paper, a method is developed for wind power system reliability modeling considering wind uncertainty, as well as wind turbine condition through health condition prediction. All wind turbine components are considered. Optimization is performed for maximizing availability or minimizing cost. Optimization is also conducted for minor repair activities to find the optimal number of joint repairs.

The wind turbine condition uncertainty and its prediction are important for wind power system reliability assessment, as well as wind speed uncertainty. Optimal CBM policies can be achieved for optimizing turbine availability or maintenance cost. Optimal preventive maintenance policies can also be achieved for scheduling minor repair activities.

This paper considers uncertainty in both wind speed and turbine conditions and incorporates turbine condition prediction in reliability analysis and CBM optimization. Optimization for minor repair activities is studied to find the optimal number of joint repairs, which was not investigated before. All wind turbine components are considered, and data from the field as well as reported studies are used.

Uses the technique of delay‐time analysis to model preventive maintenance problems of gearboxes for the Kowloon Motor Bus (KMB) Company Limited in Hong Kong. Presents a basic model of inspection maintenance, along with models of some of the variations which have been observed in the case being studied. Aims, in particular to identify the problems and requirements of KMB and then develop a delay‐time model to fit the case, as well as to determine a preventive maintenance policy derived from the model so that the total maintenance cost per unit time can be minimized. Verifies the feasibility of implementing the policy according to three criteria: workers’ utilization, downtime of the gearboxes and the monthly cost incurred by both maintenance and overhead. Compares the results with those of the current policy. Suggests recommendations to KMB for improving the current maintenance policy, and highlights the general applicability of the delay‐time modelling technique.

This paper seeks to present a decision‐making model for manufacturers to maximize their profits in reverse logistics operations.

A system dynamic model has been developed to complement with prior models and is validated using data collected from a computer company manufacturer handling returns with volumes transacted over a period of two years.

The results from the model indicate that part replacements from suppliers are more profitable than refurbished computer parts. In addition, transportation delay and supplier delay in processing returns have a significant impact on the viability of reverse logistics regardless of return volumes.

The current model is not designed for third‐party logistics (3PL) offering reverse logistics services. However, this can be accomplished by resetting some of the parameters in the model. The other limitations are exchange rate fluctuation and product depreciation which are not incorporated in the model. This is important in Asia where each country has its own currency which fluctuates with time.

This dynamic model will assist decision‐makers to test new policies related to reverse logistics, for example, liberal versus conservative return policy from supplier, shipment consolidation (longer delays) versus direct shipment, batch (longer delays) versus JIT remanufacturing, pricing of new parts versus re‐condition parts, as well as to examine its long‐term viability.

Using system dynamics to understand the profitability of reverse logistics for both replacement parts to suppliers and refurbished parts to manufacturers.

IT would be quite refreshing to have an open breeze blowing through the ranks of work study technicians these days. Away with the ponderous exponents of the mystic art and, instead, finding the experts telling the workers how easy work study really is if only you sit down and think about it. It has, of course, many difficult and complex aspects but let us not confuse the issue, since these aspects can be left to the professionals' — after all that is what they get paid for — sorting out and providing solutions to the problems!

The purpose of this paper is to prepare a methodology to evaluate availability analysis of distillery plant using Petri nets (PN). The effect of various failures, repair rate and availability of repair facilities on the system has been studied.

The PN model of a system is developed to study the dynamic behavior of the system under various working conditions. Availability analysis of the plant is presented taking into consideration of failure and repair rates of their subsystems and has been carried out using Monte Carlo simulation.

The bottle washing machine is the most critical machine from a maintenance point of view which has more compact on the system performance as compared to other machines. The availability analysis of distillery plant helps the management to adopt a suitable maintenance policy to improve upon plant production and plant availability.

The application of this proposed PN-based approach is very useful in finding the most critical subsystem and its effect on the performance of the system in terms of availability and plant production. Further, the advantage of the PN approach is that dynamic behavior of the system under consideration is modeled with graphic representation of the system and given distribution can be associated with the subsystems for analysis. The superiority of this approach over others, such as network, fault tree and Markov analysis, is outlined in the paper.

Purpose – To investigate the potential impacts of future climate change in the United Kingdom on its road and rail networks.

Methodology/approach – The climate change impacts of increasing summer temperatures, decreasing winter temperatures, increased heavy precipitation, greater numbers of extreme weather events and rises in sea level are reviewed.

Findings – Surface transportation is the most exposed element to the localised impacts of climate change. High summer temperatures will result in road rutting, rail buckling and decreased thermal comfort, whereas more intense winter precipitation will cause flooding, landslips and bridge scour across all modes. For all impacts, it is the extreme events (e.g. heat waves and storms) that are potentially the most devastating. As shown, there are some positive climate change impacts. For example, in the case of winter maintenance, all transport networks stand to benefit.

Originality/value – In order for transport to react appropriately to the potential changes in climate, it is essential to understand how the road and rail networks may be affected and to build strategies for both adaptation and mitigation into plans for future developments for both modes.

THE newly‐constituted Adult Education Committee of the Board of Education has settled down to work, and librarians of every class will await its recommendations with much interest. It embodies representatives of many associations concerned, but its character is highly academic, and possibly unduly so in view of the practical work to be examined. Some disappointment has been expressed that no librarians have been invited to serve on the Committee, even though the best work of the librarian is mainly educational, and with adults. Progress in adult educational work in the widest sense depends on proper methods of advance, and the Board of Education should by this time know that every aspect of such work has a vital interest for librarians, many of whom were doing practical work of the kind long before the subject of adult education threatened to become a cult. Even the anæmic Eastbourne Memorandum indicates that.

Recent years have highlighted the emphasis placed on quality. It is a word often heard around many an organization, but can mean different things to different people.The Japanese have certainly jumped on the bandwagon with vigour, and have tried to include total quality in almost everything they do, looking increasingly to improve their processes at every conceivable stage. Recent emphasis has been heavily placed on product reliability, thus ensuring that the final product does not let the customer down. Quality in this instance quite simply refers to the processes leading up to the end product itself. This can throw up even more tantalizing questions, such as trying to decide what your actual product is. Am I, for example, selling you, the reader, the actual journal or the information contained within? Does quality mean to you, therefore, the quality of the cover, the paper, and the print, or is it the quality of the information, or indeed both. This issue of IJHCQA, will hopefully go some way towards answering these types of questions, and take a closer look at a number of “strategies for service quality”.