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Possibilities for significant reductions in line‐haul rates and improved service are occuring through the development of the unit train principle. In this article the author describes the North American experience with unit trains.

Profit analysis of a two non‐identical unit cold standby system model with mutual changeover of the units is carried out in this paper. With mutual changeover of the unit, the operating unit, after functioning for some random amount of time, becomes standby to take rest, and the standby unit becomes operative. The failure and repair times of each unit are jointly distributed as bivariate exponential (BVE) with different parameters. Various measures of system effectiveness useful to system engineers and designers are obtained by using the regenerative point technique. Behaviour of the mean time to system failure (MTSF) and availability have also been studied graphically.

The purpose of this paper is to derive the user‐perceived availability of M‐for‐N shared protection systems composed of multiple user groups, each with a protection‐switching priority.

The paper assumes a shared protection system with M protection units and N working units. The memoryless state transition diagram viewed from the system administrator, combined with combinatorial analysis of state probabilities on protection switching, yields a generic formula of the availability viewed from an arbitrary end user.

The numerical examples of availability reveal the effect of prioritized protection switching. It is observed that the total protection capacity is constant regardless of the ways of priority grouping. The shared protection system with multiple protection units enables more flexible availability allocation compared with the case of a single protection unit.

User‐perceived reliability is still an unexplored research area. Many variations of the system treated in this paper can be applied to various applications.

The analysis provides useful information for the design and operation of, for example, telecommunication network devices. The analysis is applicable to general shared protection systems that are subject to service level agreement (SLA) involving user‐perceived reliability measures.

This paper establishes the model of the priority shared protection systems for the first time and shows a practical computation method of prioritized user‐perceived availability.

The purpose of this paper is to explore the effects of prolonged investment in one quality improvement method, which are uncertain. The authors aim to examine the extent to which sustained involvement in a quality network over five years led to improved performance against standards, and whether improvement was achieved in areas where service staff could exercise direct control.

A prospective cohort design was used to examine data from 48 UK inpatient child and adolescent mental health units between 2005/2006 and 2009/2010, which had been Quality Network for In-patient CAMHS members for two years. These were selected to remove the initial marked increase in compliance identified in an earlier study. The main outcome measure was compliance with organisation process standards.

Units meeting “excellent” quality status across all standards rose from seven (14.6 per cent) to 18 (37.5 per cent). Standards for Environment and Facilities and Access, Admission and Discharge improved the most. Units meeting the “excellent” quality status for criteria over which staff had direct control criteria rose from 17 (35.4 per cent) to 29 (60.4 per cent) over the five-year period. The unit modal quality status categorisation for criteria where staff had no direct control in 2005/2006 was “poor” (n=25; 52.1 per cent) but had progressed to “good” in 2009/2010 (n=24; 50.0 per cent).

The authors provide evidence that sustained investment in one QI method raises service compliance against standards. Trends showed improvement for direct control standards from “good” to “excellent” levels and improvement for no direct control from “poor” to “good”.

The methodology of process cost accounting is set out in a step‐by‐step format. This is a technique used when operations are not undertaken on a discrete, job‐by‐job basis.

The productivity and quality of working life of operations within a firm with multiple operating units can be improved by the diffusion of incremental improvements from one unit to another. The opportunities and problems experienced by one large multi‐unit firm in diffusing employee innovations between units are examined. It was found that incremental or Minor Technical Improvements (MTIs) do diffuse between units. Improved communication and increased under standing of the innovation process by management may increase the amount of MTI diffusion. The costs and benefits of MTI type innovation and diffusion are explored. Opportunities for more research into the diffusion of MTIs in other multi‐unit firms are discussed.

The purpose of this paper is to determine the state probabilities for a float system when overhauls are performed periodically.

First, a model is developed to express the relationship between the rate of occurrence of failure and time interval between overhauls. Then, a methodology is defined to develop differential equations for each system state in order to calculate corresponding system state probabilities.

Since it is considered that units requiring an overhaul stay in operation until replacement, the possibility of failure of those units has to be included. Then, the determination of system state probabilities has to be done iteratively.

The methodology proposed in this paper enables comparison of different designs for a float system submitted to periodic overhauls through some different performance measures. System state probabilities can also be used to determine the idle time of units, which is essential to obtain the cost of production loss and, therefore, the system maintenance cost.

This paper considers simultaneously three different factors that influence maintenance float system performance: the number of spare units and the number of maintenance crews (which mean minimising the downtime effect) and the overhaul frequency (which means decreasing the number of failures).

Planning to add a hard disk to your computer? One of the possibilities you should consider is a unit that combines the disk with a magnetic tape drive. The disk will store your data; the tape will provide the backup security you need to protect against loss of valuable files.

The purpose of this paper is to develop a dynamic opportunistic maintenance policy for a continuously monitored multi‐unit series system with integrating imperfect effect into maintenance activities.

Based on the hybrid hazard rate recursion rule, an imperfect maintenance model for a continuously monitored single‐unit system was proposed. Then by introducing the “set‐up cost” concept, a dynamic opportunistic maintenance (OM) policy for multi‐unit‐series‐systems was developed. The optimal maintenance activities were determined by maximizing the short‐term cumulative OM cost saving for the continuously monitored system. A numerical example is given to show how the proposed dynamic OM policy proceeded.

The simulation results imply that the proposed policy is better than the policy to maintain the system units separately and the policy to maintain the system units together.

The proposed dynamic maintenance policy can fulfill the real plant environment that maintenance action is always imperfect and maintenance information is only available over a short term. Under this policy, the maintenance manager can easily and quickly adjust the maintenance schedule at any moment according to the working condition of the system.

The proposed model in this paper integrates the imperfect maintenance effect into condition‐based predictive maintenance, and the system maintenance schedule is dynamically determined based on the short‐term information of the system.