Bow Tie — Advanced mode
The advanced version adds full probabilistic quantification.
Differences from the simple node
| Feature | Simple | Advanced |
|---|---|---|
| Probability on events | — | ✓ |
| AND / OR logic gates | — | ✓ |
| PFD on barriers | — | ✓ |
| ERC probability calculation | — | ✓ |
| MOCUS analysis | — | ✓ |
Node structure
- Events — carry a probability or an occurrence frequency
- Barriers — carry a reduction factor (PFD: Probability of Failure on Demand)
- AND gates — all parent events must occur simultaneously
- OR gates — a single parent event is enough
- Conditions — conditioning events that modify the probability of an arc
Diagram tab
Graphic editing of the bow tie: adding nodes (events, barriers, conditions), connections, assigning logic gates, entering probabilities and PFDs.
Probabilities tab
Tabular summary of calculated probabilities:
- Probability of the ERC (annual frequency or per demand)
- Probability of each consequence
Minimal cut sets (MOCUS) tab
Result of the MOCUS (Method for Obtaining Cut Sets) analysis:
- List of minimal cut sets, ranked by decreasing probability
- Each cut set = minimal combination of basic events leading to the ERC
- Helps identify the most critical failure combinations to address first