Sequential
Hazard Analysis
CE-653 - Hazards and Analysis
Methods
32
}Can be extended with 13-value logic and timeframes:
}Eichelberger’s Two-Step
Approach:
}Procedure/Step 1 – Determine all changing Y signals
1.Set changing input vector
signals to intermediate1/2 values, and all other x or y
signals to their previous values
2.Evaluate Yi functions to determine changes from 1 or 0 to
1/2
3.Propagate any 1/2 Yi change
to corresponding yi change and repeat process until no
further changes to Yi occur
}Procedure/Step 2 – Determine all stabilising Y signals
}Set changing input vector
signals to their final values, 1 or 0, and all other x or y
signals to their previous values, as determined by Procedure
1
}Evaluate Yi functions to determine changes from 1/2 to 1
or 0
}Propagate any 0 or 1 Yi change
to corresponding yi change and repeat process until
no further changes to Yi occur
18/3/2014