Libro

. Systems engineering is focused on the system as a whole; it emphasizes its total operation. It looks at the system from the outside, that is, at its interactions with other systems and the environment, as well as from the inside. It is concerned not only with the engineering design of the system but also with external factors, which can significantly constrain the design. These include the identification of customer needs, the system operational environment, interfacing systems, logis- tics support requirements, the capabilities of operating personnel, and such other factors as must be correctly reflected in system requirements documents and accommodated in the system design.

2. While the primary purpose of systems engineering is to guide, this does not mean that systems engineers do not themselves play a key role in system design. On the contrary, they are responsible for leading the formative (concept devel- opment) stage of a new system development, which culminates in the functional design of the system reflecting the needs of the user. Important design decisions at this stage cannot be based entirely on quantitative knowledge, as they are for the traditional engineering disciplines, but rather must often rely on qualitative judgments balancing a variety of incommensurate quantities and utilizing expe- rience in a variety of disciplines, especially when dealing with new technology.

3. Systems engineering bridges the traditional engineering disciplines. The diver- sity of the elements in a complex system requires different engineering disci-

plines to be involved in their design and development. For the system to perform correctly, each system element must function properly in combination with one or more other system elements. Implementation of these interrelated functions is dependent on a complex set of physical and functional interactions between separately designed elements. Thus, the various elements cannot be engineered independently of one another and then simply assembled to produce a working system. Rather, systems engineers must guide and coordinate the design of each individual element as necessary to assure that the interactions and interfaces between system elements are compatible and mutually supporting. Such coor- dination is especially important when individual system elements are designed, tested, and supplied by different organizations.

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