Nianfu Yang

Availability of a man-machine system with critical and non-critical human error

Abstract This paper presents a newly developed probabilistic model representing two units in parallel and one on standby system with critical and non-critical human error. Repair times of the failed system are arbitrarily distributed while all other transition time distributions are negative exponential. A general formula for the system steady-state availability is developed with the aid of the method of supplementary variables, the Markov approach and Laplace transforms. Specific plots and tables are shown to demonstrate the impact of critical and non-critical human errors on system steady-state availability.

Stochastic analysis of standby systems with common-cause failures and human errors

Abstract This paper presents two newly developed Markov models representing two identical unit standby systems with common-cause failures and human errors. The system reliability, mean time to failure, variance of time to failure, and time-dependent system availability expressions are developed. Some plots are shown.

Reliability and availability analysis of warm standby systems with common-cause failures and human errors

Abstract This paper presents reliability and availability analysis of warm standby systems with common-cause failures and human errors. Expressions for system availability, reliability, mean time to failures, and time to failure variance are developed. Selective plots are shown to demonstrate the effect of common-cause failures and human errors on system reliability, availability, and mean time to failure.

Availability analysis of a robot with safety system

This paper presents availability analysis of a system composed of a robot and its associated safety system. The failed robot system is repairable and its associated repair rates could be constant or non-constant. The supplementary variable and Markov techniques were employed to obtain expressions for steady state availability, state probabilities, and Laplace transform of the state probabilities. Various plots are presented.

Probabilistic analysis of a maintainable system with human error

Presents a newly developed stochastic model for performing reliability and availability analyses of a repairable general standby human‐machine system with increasing human error rates and arbitrary failed system repair rates. Also, the model takes into consideration the occurrence of common‐cause failures. The joint‐density function approach, supplementary variable techniques, and linear ordinary differential equation methods were used to perform analyses. Develops the expressions for steady state availability, the system time‐dependent availability, reliability and mean time to failure.

Stochastic analysis of an active-stand by redundant network with two types of common-cause failures

This paper presents probabilistic analysis of a reliability system composed of two active and one standby units. The system can fail either due to normal failures or two types of common-cause failures. The failed system is repairable. The supplementary variable and Markov methods were used to perform probabilistic analysis. Expressions for system availability and state probabilities are presented along with various plots

Availability analysis of a repairable standby human-machine system

Abstract This paper presents a model representing a two units active and one unit on standby human-machine system with general failed system repair time distribution. In addition, the model takes into consideration the occurrence of common-cause failures. The method of linear ordinary differential equation is presented to obtain general expressions for system steady state availability for failed system repair time distributions such as Gamma, Weibull, lognormal, exponential, and Rayleigh. Generalized expressions for system reliability, time-dependent availability, mean time to failure, and system variance of time to failure are also presented. Selected plots are presented to demonstrate the impact of human error on system steady state availability, reliability, time-dependent availability, and mean time to failure.

Human error analysis of a standby redundant system with arbitrarily distributed repair times

Abstract This paper presents human error analysis of a (two units working and one on standby) system with arbitrarily distributed repair times. The supplementary vairables method is used to develop the system availability expressions. A general formula for the system steady-state availability is developed when the failed system repair times are gamma distributed. Time-dependent availability, system reliability with repair, mean time to failure and variance of time to failure formulae are developed for some particular cases. Selective plots are shown to demonstrate the impact of critical human error on system availability and reliability.

Formulas for analyzing a redundant robot configuration with a built-in safety system

This paper presents formulas to perform reliability and availability analyses of a system having two identical robots and one safety system. Formulas for system expected time to failure, reliability, and Laplace transforms of system availability are developed along with various plots demonstrating the end results.

Comparisons of block diagram and Markov method system reliability and mean time to failure results for constant and non-constant unit failure rates

This paper presents a comparison of system reliability and mean time to failure results obtained using two different methods (i.e. block diagram and Markov) for the same system with constant and non-constant unit failures rates. The device of stages approach is used to obtain the non-constant unit failure rate when using the Markov method.