ETL 1110-2-560
30 Jun 01
R(t)
1.0
β=1/2
0.368
β=1.0
β = 4.0
1/λ
t
Figure 4. Reliability function for Weibull distribution
h(t)
β=4
β=1
λ
β=1/2
t
Figure 5. Hazard function for Weibull distribution
proper, coordinated function leads to its proper operation. In reliability analysis, it is therefore important
to model the reliability of the individual items as well as the relationship between the various items to
determine the reliability of the system as a whole. This ETL applies the reliability block diagram (RBD)
method as outlined in MIL-STD-756B to model conventional probability relationships of collections of
independent components and systems.
8. System Reduction
The number of discrete mechanical and electrical components in a lock and dam requires system reduc-
tion to reduce the vast complexity of numerous components into smaller groups of critical components.
The reliability models should be developed to the level of detail for which information is available and for
which failure rate (or equivalent) data can be applied. Functional elements not included in the mission
reliability model shall be documented, and rationale for their exclusion shall be provided.
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