P.P. Gupta

Reliability and MTTF analysis of a non repairable parallel redundant complex system under hardware and human failures

This paper deals with Reliability and MTTF analysis of a two-state complex non-repairable system, consisting of two sub-systems A and B arranged in series, incorporating the concept of hardware and human failures. The failure times for the system follow exponential distribution. Laplace transforms of the various state probabilities have been derived and then reliability of the complex system, at any time t, has been computed by inversion process. MTTF has also been evaluated. In the end various graphs have also been plotted so as to explain the practical utility of the model.

Cost analysis of a multi-component parallel redundant complex system with overloading effect and waiting under critical human error

Abstract The cost analysis of a multi-component parallel redundant complex system is considered, incorporating the concept of overloading effect and waiting time for repair under critical human error. Failure and waiting times follow an exponential time distribution, whereas repair time follows a general distribution. Using the supplementary variable technique, Laplace transforms of the probabilities of the complex system being in various states have been computed. Some graphs have been plotted to highlight the main results.

Reliability analysis of a two state repairable parallel redundant system under human failure

Abstract In this paper, the investigations have been carried out for the MTTF and reliability analysis of a repairable two-unit redundant electronic equipment having two states under human failures. The two-unit repairable parallel redundant system suffers two types of failures; viz; unit failure and human failure. Human failure brings the system to a complete failure stage. There is only one server who is always available. Laplace transforms of the probabilities of the complex system being in up and down states have been derived and have been inverted to obtain time dependent probabilities. Two graphs have also been given in the end.

Reliability and MTTF analysis of a three-state multi-component parallel redundant system under overloading effect and waiting

Abstract Investigations have been carried out for the evaluation of reliability and MTTF analysis of a three-state multi-component parallel redundant complex system incorporating the concept of overloading effect and waiting. The complex system consists of two-subsystems A and B , connected in parallel. Subsystem A consists of M non-identical units in series whereas B has N non-identical units in series.

Availability and MTTF analysis of a three-state parallel redundant multi-component system under critical human failures

Abstract This paper deals with the availability and mean time to failure of a single server complex system made up of two classes A and B under critical human errors. Sub-system A has two identical components arranged in parallel whereas B has N non-identical components arranged in series. The complex redundant system has three states, viz. good, degraded, failed and suffers two types of failures, viz. unit failure and failure due to critical human errors. The failure and repair times for the system follow exponential and general distributions respectively. Laplace transforms of the probabilities of the complex system being in various states have been obtained along with steady state behaviour of the equipment. A numerical example has also been appended in the end to highlight the important results. There is only one repair facility, which is availed only when the system is in failed state due to failure of sub-system B.

Cost analysis of a three-state repairable redundant complex system under various modes of failures

Abstract In this paper, a mathematical model for the evaluation of expected profit during the time interval (0, t] and availability at an instant t under human failure has been set up. The model consists of two subsystems arranged in parallel having three states for operation. The first subsystem consists of two identical units in series whereas the second subsystem has only one unit. Failure and repair times for the system follow exponential and general distributions respectively. Repair is undertaken only when the system is in a reduced efficiency state. Using supplementary variable and Laplace transforms techniques, time dependent probabilities of the complex system being in various states have been computed along with the steady state behaviour of the system. A particular case has also been discussed to highlight the important results.

Cost analysis of a two unit, three state standby redundant complex system with two types of repair facilities under waiting

Abstract This paper deals with the cost analysis of a two unit, three state standby redundant complex system, incorporating the concept of two types of repair facilities, viz. minor and major repair. The concept of waiting time for the major repair of the failed system has also been introduced. The system can suffer from two types of failures, namely catastrophic and partial. Failure and waiting times of units follow exponential time distribution, whereas repair of units follows general time distribution. Using the supplementary variable technique, Laplace transforms of probabilities of the complex system being in various states have been computed. In addition, using Abels lemma, steady state behaviour has also been examined. Some important graphs have been sketched at the end to highlight the important results.

Point-wise availability of a two-unit standby redundant electronic equipment under human failure

Abstract This paper deals with the evaluation of point-wise availability and M.T.T.F., of a two-unit standby redundant electronic equipment, incorporating the concept of human failures. Single service facility is available for the service of constant failure. Using the supplementary variable technique, general equations are set up for deriving the above two measures. In addition, steady state availability is also derived and some important graphs have been sketched in the end.

MTTF and availability evaluation of a two-unit, two-state, parallel redundant complex system with constant human failure

Abstract This paper deals with MTTF and availability analysis of a two-state complex general repairable system consisting of two units arranged in parallel. Single service facility is available for the service of unit failure. The failure and repair times for the system follow exponential and general distributions respectively. Laplace-transforms of the various state probabilities have been derived and steady state behaviour of the system has also been examined. Availability at any time is obtained by the inversion process. To make the system more compatible with the physical situation, MTTF for the system has also been evaluated and various graphs have been plotted to highlight the utility of the model.

Cost function analysis of a standby redundant non-repairable system subjected to different types of failures

Abstract In this paper, cost function analysis of a non-repairable standby system has been studied incorporating the concept of environmental effect. The complex system consists of two sub-systems, say A and B, connected in series. Subsystem A consists of two units connected in standby redundancy, whereas subsystem B consists of a simple system. The complex system has been subjected to various kinds of failures, viz. hardware failure, human failure and self life failure. The failure times for the system follow exponential distribution. Laplace transforms of the various state probabilities have been derived and then reliability is obtained by the inversion process. Moreover, an important parameter of reliability, i.e. MTTF (mean time to failure), has also been evaluated. Also, few graphical illustrations are also given at the end to high-light the important results.