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Foundation ::
Engineering Applications ::
CUTSETS
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CUTSETS
Minimal Cut Set Calculation for Digraph and Fault Tree Reliability Models
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Moderators:
Adopt This Application!
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SOURCE CODE AVAILABLE
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Fault tree and digraph models are frequently used for system failure
analysis. Both type of models represent a failure space view of the system
using AND and OR nodes in a directed graph structure. Fault trees must have
a tree structure and do not allow cycles or loops in the graph. Digraphs allow
any pattern of interconnection between loops in the graphs.
A common operation performed on digraph and fault tree models is the
calculation of minimal cut sets. A cut set is a set of basic failures that
could cause a given target failure event to occur. A minimal cut set for a
target event node in a fault tree or digraph is any cut set for the node with
the property that if any one of the failures in the set is removed, the occurrence
of the other failures in the set will not cause the target failure
event.
CUTSETS will identify all the minimal cut sets for a given node. The
CUTSETS package contains programs that solve for minimal cut sets of fault
trees and digraphs using object-oriented programming techniques. These
cut set codes can be used to solve graph models for reliability analysis and
identify potential single point failures in a modeled system.
The fault tree minimal cut set code reads in a fault tree model input
file with each node listed in a text format. In the input file the user specifies
a top node of the fault tree and a maximum cut set size to be calculated.
CUTSETS will find minimal sets of basic events which would cause the
failure at the output of a given fault tree gate. The program can find all
the minimal cut sets of a node, or minimal cut sets up to a specified size.
The algorithm performs a recursive top down parse of the fault tree, starting
at the specified top node, and combines the cut sets of each child node
into sets of basic event failures that would cause the failure event at the
output of that gate. Minimal cut set solutions can be found for all nodes in
the fault tree or just for the top node.
The digraph cut set code uses the same techniques as the fault tree cut
set code, except it includes all upstream digraph nodes in the cut sets for a
given node and checks for cycles in the digraph during the solution process.
CUTSETS solves for specified nodes and will not automatically solve for all
upstream digraph nodes. The cut sets will be output as a text file.
CUTSETS includes a utility program that will convert the popular COD
format digraph model description files into text input files suitable
for use with the CUTSETS programs.
CUTSETS carries the NASA case number ARC-13286. It was originally released as part of the NASA COSMIC collection.
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