Praveen Gupta

Reliability analysis of a system with preventive maintenance, inspection and two types of repair

Abstract This paper considers a two-unit (identical) parallel system with facilities of preventive maintenance, inspection and two types of repair, type I and type II. These two types of repair facilities have a considerable difference in their costs. Both the units of the system can fail simultaneously due to some common-cause or they can fail one by one. The time of failure of a unit and system, the commencement of maintenance and inspection are assumed to be constant while repair and maintenance times are arbitrarily distributed. Various measures of system effectiveness are evaluated using regenerative point technique.

Stochastic analysis of a parallel system with common cause failure, preventive maintenance and two types of repair

Abstract This paper studies a two-unit (identical) parallel system with facilities of preventive maintenance and two types of repair, i.e. regular and occasional. When the regular repairman is unable to repair the unit/system, the occasional (expert) repairman is called for. The system can also fail due to common cause. The time of the failure of a unit and the system, the commencement of maintenance and to call the occasional repairman are assumed to be constant while the repair and maintenance times are arbitrarily distributed. The system is analysed by using regenerative point technique to obtain various economics related measures, such as mean time to system failure, steady state availability, probability that the repairman is busy, expected number of visits by the occasional repairman and the expected profit earned by the system.

Analysis of a two-engine aeroplane model with two types of failure and preventive maintenance

Abstract This paper deals with an aeroplane model; namely, a two-unit (non-identical) parallel system with dual mode of failures—(1) failure due to change in operating characteristics and (2) failure due to common cause. The system goes for preventive maintenance at random epochs. We assume that the failure, repair and maintenance times are stochastically independent random variates each having an arbitrary distribution. Using the regenerative point technique several measures of reliability are obtained. Certain important results have been derived as particular cases.

A single unit multicomponent system subject to various types of failures

Abstract This paper investigates the mathematical model of a reparable system with several possible states of operation, failure and repair. There is also an inspection facility for deciding whether on failure, the system needs minor repair or overhaul. Repair rates are arbitrary functions of the time spent. All other transition rates are constant. Several reliability characteristics of interest to system designers as well as operations managers have been computed and results obtained earlier are verified as particular cases.

Analysis of a two-unit cold standby system with three modes

Abstract This paper analyses a two-unit cold standby system under the assumption that each unit works in three different modes—normal, partial failure and total failure. Failure time distributions of units are exponential, whereas repair time distributions are arbitrary. Breakdown of the system occurs when both the units are in total failure mode. Several reliability characteristics of interest to system designers as well as operations managers have been evaluated.

Stochastic analysis of a two-unit parallel system with partial and catastrophic failures and preventive maintenance

Abstract This paper studies a two-unit parallel system with each unit having two types of failure and two modes of operation—normal or partial failure mode. A unit fails either due to change in operating characteristics or due to catastrophe. The system goes for preventive maintenance randomly (in time). Failure rates are constant while repair and (preventive) maintenance rates are general. Using the theory of regenerative and Markov-renewal processes several important measures of reliability are obtained.

Cost-benefit analysis of a system with intermittent repair and inspection under abnormal weather

Abstract This paper studies a repairable system with intermittent repair. Weather under which the system works changes randomly (in time) from normal to abnormal weather and vice-versa. By intermittent repair, we mean that the repair facility is not available instantaneously but takes random time to be available. The system operating under abnormal weather is sent for inspection randomly with Poisson process. Failure rates of the system and rates of change of weather are constant while repair times, inspection time and inter-inspection time are arbitrarily distributed. The system is analysed by using regenerative point technique to obtain various economic measures such as mean time to system failure, steady state availability, probability that the repairman is busy, expected number of visits by repairman and expected profit earned by the system.

Stochastic analysis of a man-machine system with critical human error

Abstract This paper studies various economic reliability measures of a repairable man-machine system. The physical condition (good/poor) of the operator may affect the performance of the system. Repair time distributions of the system are general while all other transition time distributions are negative exponential. The system can be in one of the three modes—normal, partial failure and total failure. Regenerative technique in MRP is applied to obtain several reliability characteristics of interest to system designers.

A two-unit deteriorating standby system with inspection

Abstract This paper studies a single server two-unit standby system in which the standby can fail when offline and its repair starts only after knowing about its failure from its time to time inspection. The inter-inspection time is assumed to be arbitrarily distributed. Various measures of reliability useful to system designers and operations managers are obtained.

Stochastic behaviour of a two-unit standby system with better utilization of units

Abstract This paper obtains various measures of reliability of a two-unit redundant system with three modes. Upon partial failure of an operative unit the cold standby starts operation only when it becomes active. A single service facility is available (1) for repairing a partially or totally failed unit and (2) to activate the cold standby unit whenever required. Failure time distributions are negative exponential while repair and activating time distributions are general.