Page 271 - Mechanical Engineers' Handbook (Volume 2)

262 Analysis, Design, and Information Processing

Figure 2 One representation of three systems engineering steps within each of three life-cycle phases.

In actual practice, the steps of the systems process (formulation, analysis, and interpre-
tation) are applied iteratively, across each of the phases of a systems engineering effort, and
there is much feedback from one step (and one phase) to the other. This occurs because of
the learning that is accomplished in the process of problem solution. Underlying all of this
is the need for a general understanding of the diversity of the many systems engineering
methods and algorithms that are available and their role in a systems engineering process.
The knowledge taxonomy for systems engineering, which consists of the major intellectual
categories into which systems efforts may be categorized, is of considerable importance. The
categories include systems methods and measurements, systems engineering processes or
systems methodology, and systems management. These are used, as suggested in Fig. 3, to
produce a system, which is a generic term that we use to describe a product or a service.
The methods and metrics associated with systems engineering involve the development
and application of concepts that form the basis for problem formulation and solution in
systems engineering. Numerous tools for mathematical systems theory have been developed,
including operations research (linear programming, nonlinear programming, dynamic pro-
gramming, graph theory, etc.), decision and control theory, statistical analysis, economic
systems analysis, and modeling and simulation. Systems science is also concerned with
psychology and human factors concepts, social interaction and human judgment research,
nominal group processes, and other behavioral science efforts. Of very special significance
for systems engineering is the interaction of the behavioral and the algorithmic components
of systems science in the choice-making process. The combination of a set of systems science
and operations research methods and a set of relations among these methods and activities
constitutes what is known as a methodology. References 3 and 4 discuss a number of systems
engineering methods and associated methodologies for systems engineering.
As we use it here, a methodology is an open set of procedures that provides the means
for solving problems. The tools or the content of systems engineering consists of a variety
of algorithms and concepts that use words, mathematics, and graphics. These are structured
in ways that enable various problem-solving activities within systems engineering. Particular
sets of relations among tools and activities, which constitute the framework for systems