2-Unit Standby System and Alertness of the Worker

This paper analyses two 2-unit standby systems. The failure times and repair times of the units are s-independent and have general distributions. The worker becomes alert whenever a unit is switched on and he attends the on-line unit. His alertness duration has a general distribution. In model 1 if an on-line unit fails while the worker is alert, the repair facility makes it a type 1 unit. If it fails while the worker is not alert, the failed unit becomes a type 2 unit after the repair. If off-line, type 1 unit does not fail. If off-line, type 2 unit is warm. The dual case is considered in model 2. Using renewal theory, availability and reliability of the systems are treated. The main paper describes the models and a Supplement presents the Laplace transforms of the availability and reliability.