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A system is a construct or collection of
different elements that together produce results not obtainable by the elements
alone. The elements, or parts, can include people, hardware, software,
facilities, policies, and documents; that is, all things required to produce
systems-level results. The results include system level qualities,
properties, characteristics, functions, behavior and performance. The value
added by the system as a whole, beyond that contributed independently by the
parts, is primarily created by the relationship among the parts; that is, how
they are interconnected (Rechtin, 2000).
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Systems Engineering is an engineering discipline whose responsibility
is creating and executing an interdisciplinary process to ensure that the
customer and stakeholder's needs are satisfied in a high quality,
trustworthy, cost efficient and schedule compliant manner throughout a
system's entire life cycle. This process is usually comprised of the
following seven tasks: State
the problem, Investigate
alternatives, Model the
system, Integrate, Launch the system, Assess performance, and Re-evaluate. These functions can be
summarized with the acronym SIMILAR: State, Investigate, Model, I ntegrate,Launch, Assess and Re-evaluate. This Systems
Engineering Process is shown in Figure 1. It is important to note that the
Systems Engineering Process is not sequential. The functions are performed in
a parallel and iterative manner.
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State the problem
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The problem statement starts with a
description of the top-level functions that the system must perform: this
might be in the form of a mission statement, a concept of operations or a
description of the deficiency that must be ameliorated. Most mandatory and
preference requirements should be traceable to this problem statement.
Acceptable systems must satisfy all the mandatory requirements. The
preference requirements are traded-off to find the preferred alternatives.
The problem statement should be in terms of what must be done, not how to do it. The problem statement should express the
customer requirements in functional or behavioral terms. It might be composed
in words or as a model. Inputs come from end users, operators, maintainers,
suppliers, acquirers, owners, regulatory agencies, victims, sponsors,
manufacturers and other stakeholders.
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