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Unformatted text preview: desirable, though team composition and
leadership can be expected to change as the system
progresses from phase to phase. change
interoperable, and product data are readily accessible
and accurate. For more on the characteristics of
automated environments, see for example Carter and
Baker, Concurrent Engineering,1992.
Technology Insertion. Projects are sometimes initiated
with known technology shortfalls, or with areas for which
new technology will result in substantial product
improvement. Technology development can be done in
parallel with the project evolution and inserted as late as
the PDR. A parallel approach that is not dependent on
the development of new technology must be carried
unless high risk is acceptable. The technology
development activity should be managed by the project
manager and system engineer as a critical activity.
Verification vs. Validation. The distinction between
verification and validation is significant: verification
consists of proof of compliance with specifications, and
may be determined by test, analysis, demonstration,
inspection, etc. (see Section 6.6). Validation consists of
proof that the system accomplishes (or, more weakly,
can accomplish) its purpose. It is usually much more
difficult (and much more important) to validate a system
than to verify it. Strictly speaking, validation can be
accomplished only at the system level, while verification
must be accomplished throughout the entire system
architectural hierarchy. 3.8 Funding: The Budget Cycle NASA operates with annual funding from
Congress. This funding results, however, from a
three-year rolling process of budget formulation, budget
enactment, and finally, budget execution. A highly
simplified representation of the typical budget cycle is
shown in Figure 9.
NASA starts developing its budget each January
with economic forecasts and general guidelines being
provided by the Executive Branch's Office of
Management and Budget (OMB). In early May, NASA
conducts its Program Operating Plan (POP)...
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