addLatent {FaultTree}

Add a Latent Component Event

Description

Modifies an existing fault tree with the addition of a latent component event.

Usage

addLatent(DF, at, mttf, mttr=NULL, inspect=NULL, risk="mean",
		display_under=NULL, tag="", label="",
		name="", name2="", description="")

Arguments

DF

A fault tree dataframe such as returned from ftree.make or related add... functions.

at

The ID of the parent node for this addition.

mttf

The mean time to failure. It is the user's responsibility to maintain constant units of time.

mttr

The mean time to repair (restore). This should only be provided when system remains at risk, while repair is in progress, as it modifies probability by factor "pzero". It is the user's responsibility to maintain constant units of time.

inspect

The time interval between inspections for the dormant component. (It will be possible upon future development to enter the string for the named inspection dataframe object. In this case the inspection object will be read to get the inspection interval. An inspection object must be a dataframe with interval and duration columns. If a positive duration value other than zero is found it is taken that the system is at risk during the time of inspection. An unavailable probability calculated as duration/(interval+duration) will be added to the fractional downtime.

risk

An opportunity to utilize the "max" risk probability occuring at the end of inspection duration.

display_under

Optionally, the ID of a sibling event under an OR gate for vertical alignment of the component node in the graphic display.

tag

A very short identifying string (typically 5 characters or less) uniquely identifying a basic event for minimal cutset evaluation

label

An identifying string for the logic gate. Use of label in ftree.make defines the convention for rest of tree construction.

name

A short identifying string (typically less than 24 characters)

name2

A second line, if needed for the identifying string label

description

An optional string providing more detail for the basic event.

Value

Returns the input fault tree dataframe appended with an entry row for the defined component event.

References

Nicholls, David [Editor] (2005) System Reliability Toolkit Reliability information Analysis Center

O'Connor, Patrick D.T. (1991) Practical Reliability Engineering John Wiley & Sons

Vesely, W.E., Goldberg, F.F., Roberts, N.H., Haasl, D.F. (1981) Fault Tree Handbook U.S. Nuclear Regulatory Commission

Vesely, W.E., Stamatelato, M., Dugan, J., Fragola, J., Minarick, J., Railsback, J. (2002) Fault Tree Handbook with Aerospace Applications NASA

Doelp, L.C., Lee, G.K., Linney, R.E., Ormsby R.W. (1984) Quantitative fault tree analysis: Gate-by-gate method Plant/Operations Progress Volume 3, Issue 4 American Institute of Chemical Engineers

Examples

mytree <-ftree.make(type="and")
mytree <- addLatent(mytree, at=1, mttf=5,mttr=12/8760,inspect=1/26, name="e-gen set fails")