Ballast as a part of the railway system plays an important role in the operation of the railways and also has a great impact on repair and maintenance activities. Hence most of the repair and maintenance activities in traditional railway systems are due to the defections in the ballast layer and therefore most of the maintenance budget is spent on repairing these defects. These repair and maint...

The objective of this paper is to study the M/M/R machine repair queueing system with mixed standbys. The life-time and repair time of units are assumed to be exponentially distributed. Failed units are repaired on FCFS basis. The standbys have switching failure probability q (0≤q≤1). The repair facility of the system consists of R permanent as well as r additional removable repairmen. Due to i...

In this paper we consider a repair shop location problem with uncertainties in demand. New repair shops have to be opened at a number of locations. At these local repair shops, customers arrive with broken, but repairable, items. Customers go to the nearest open repair shop. Since they want to leave as soon as possible, an inventory of working items is kept at the repair shops. A customer immed...

Soft, real-time distributed graph coloring is presented as a simplification of the problem of distributed resource management in an environment where communication is expensive and subject to relatively high latency. The resources are subject to dynamic task sets that may produce critical or super-critical loading – the objective is to quickly compute reasonable schedules for the resources that...

A stochastic programming model of optical ber manufacturing is cre ated The purpose is to set the best ber manufacturing goals while accounting for the uncertainty primarily in the yield and secondly in the demand The model is solved for the case when the data follows a multivariate discrete distribution The model is also solved for the case when the distribution is approximated by a multivaria...

A generalized age-replacement policy with age-dependent minimal repair and random leadtime is considered. A model is developed for the average cost per unit time and is based on the stochastic behavior of the assumed system and reflects the cost of storing a spare as well as the cost of system downtime. Determination of the minimum-cost policy time is described and illustrated with a numerical ...

This investigation deals with the transient analysis of the machine repair system consisting of M-operating units operating under the care of single repairman. To improve the system reliability/availability, Y warm standby and S cold standby units are provided to replace the failed units. In case when all spares are being used, the failure of units occurs in degraded fashion. In such situation ...

Many seasonal macroeconomic time series are subject to changes in their means and variances over a long time horizon. In this paper we propose a general treatment for the modelling of time-varying features in economic time series. We show that time series models with mean and variance functions depending on dynamic stochastic processes can be sufficiently robust against changes in their dynamic...

In the present investigation, we deal with the reliability characteristics of a repairable system consisting of two independent operating units, by incorporating the coverage factor. The probability of the successful detection, location and recovery from a failure is known as the coverage probability. The reboot delay and common cause shock failure are also considered. The times to failure of t...