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 ...

Pessimistic control algorithms for replicated data permit only one partition to perform update operations at any time so as to ensure mutual exclusion of the replicated data object. Existing availability modelling and analyses of pessimistic control algorithms for replicated data management are constrained to either site-failure-only or link-failure-only models, but not both, because of the lar...

The present investigation deals with a machine repair problem consisting of cold and warm standby machines. The machines are subject to breakdown and are repaired by the permanent repairman operating under N-policy. There is provision of one additional removable repairman who is called upon when the work load of failed machines crosses a certain threshold level and is removed as soon as the wor...

The machine repair problem with spares and additional repairman is analyzed. The interfailure and repair times of the units are general identical and independently distributed. The failure and repair rates are assumed to be state dependent. Using diffusion approximation technique, we obtain the queue size distribution under steady state. The average number of failed units, average number of ope...

Suppose G=(V,A) be an undirected graph with n nodes and a source vertex s Є V. Each node has a problem that must be solved by the repairman that has send. We are given the time required by the repairman to travel among nodes. The objective is to find a tour that minimizes the total waiting time of all the problems that are waiting to be solved. Traveling Repairman problem (TRP) is also known as...

The travelling repairman problem (TRP) is a scheduling problem in which a repairman must visit locations to perform some task. Each location has a time window in which the repairman is allowed to arrive. The objective of this problem is to maximize the number of tasks performed. In this paper, we consider a special case in which all the locations are on a straight line, the tasks have no proces...

We assume a Boolean parallel system with exponentially distributed component failure times. In order to maximize the lifetime of the system we consider a repairman with Erlang-k distributed repair time. By extending the classical exponential case k = 1 to k ≥ 2 different repair semantics arise in this context. In the case of restart repair semantics we show that a repairman should have few Erla...

The input to the unrooted traveling repairman problem is an undirected metric graph and a subset of nodes, each of which has a time window of unit length. Given that a repairman can start at any location, the goal is to plan a route that visits as many nodes as possible during their respective time windows. A polynomial-time bicriteria approximation algorithm is presented for this problem, gain...

In this paper, we analyze a machine repairable system with warm spares and two repairmen. The first repairman never takes vacations. The second repairman leaves for a vacation of random length when the number of the failed units is less than N. At the end of a vacation period, this repairman returns back if there are N or more failed units accumulated in the system. Otherwise this repairman goe...

In this paper, we model a cold standby repairable system with one repairman. Suppose that the system consists of two dissimilar components and one repairman, in which component 1 is the major working unit and component 2 is the cold stand-by unit, component 1 has priority in use and repair; then the repairman takes a single vacation. Under these assumptions , we derive a model of partial differ...