Markov Calculation Equations
The following table defines the equations for Markov calculations. General descriptions of these calculations appear in Calculation Options Page. Definitions of notations appear in Markov Equation Notations.
Calculation
Equation
Availability
Capacity
Conditional failure intensity
Conditional repair intensity
Cost per unit time
Failure density
Here, Pi(t) is calculated considering that all failed states are absorbing states.
Failure frequency
Failure rate
Frequency of departures
Frequency of departures from state i:
Frequency of transitions
Frequency of transitions from state i to state j:
Frequency of visits
Frequency of visits to state i:
Mean availability
Mean capacity
Mean cost
Mean state probability
Mean unavailability
MTBF
Mean time to failure, steady state OR Mean time to first failure
The actual calculations are not discussed.
Mean time to failure, steady state
MTTR
Number of departures
Number of departures from state i:
Number of failures
Number of failures from state i:
Number of repairs
Number of repairs from state i:
Number of transitions
Number of transitions from state i to state j:
Number of visits
Number of visits to state i:
Reliability
Here, Pi(t) is calculated considering that all failed states are absorbing states.
Repair frequency
State probability
Individual state probabilities are calculated using information given in the Markov diagram. The probability of state i at time t, Pi(t), is calculated using the transition matrix and the initial state vector by the Fourth-Order Runge-Kutta Method. The error tolerance, ∈, is used to obtain the desired accuracy and stop the iterations. If ∈ is very small, then the computational time will be high; however, providing that round-off errors are negligible, results will be more accurate. If the system is repairable, then steady state results of individual state probabilities are calculated by solving a set of linear equations that correspond to the steady state behavior of the system.
Time spent in state
Total capacity
Total cost
Total downtime
Total uptime
Unavailability
Unreliability