Definitions of Systems Engineering

The Chief Systems Engineer (CSE) normally reports to the Project Manager and focuses upon building the system in question. The overall process that the CSE employs is known as Systems Engineering, a central theme in this text. We will define Systems Engineering in terms of increasing complexity and detail in various parts of this book, starting here with five relatively simple expressions, namely:

1. As developed by the International Council on Systems Engineering (INCOSE)

2. As articluated by the Department of Defense (DoD)

3. As represented in an earlier text by this author

4. As summarized by the Defense Systems Management College (DSMC)

5. As viewed by the National Aeronautics and Space Administration (NASA)

The INCOSE definition is that Systems Engineering is [1.2]:

An interdisciplinary approach and means to enable the realization of successful systems.

This definition is rather sparse and emphasizes three aspects: ''interdisciplinary,'' ''realization,'' and ''successful.'' Especially for large-scale systems, it is clearly necessary to employ several disciplines (e.g., human engineering, physics, software engineering, and management). Realization simply confirms the fact that systems engineering processes lead to the physical construction of a real-life system (i.e., it goes beyond the formulation of an idea or concept). Finally, our expectation is that by utilizing the various disciplines of systems engineering, the outcome will be a successful system, although this result is certainly not guaranteed.

A definition provided by the Department of Defense (DoD), a strong supporter as well as user of systems engineering as a critical discipline, is that Systems Engineering [1.3]:

Involves design and management of a total system which includes hardware and software, as well as other system life-cycle elements. The systems engineering process is a structured, disciplined, and documented technical effort through which systems products and processes are simultaneously defined, developed and integrated. Systems Engineering is most effectively implemented as part of an overall integrated product and process development effort using multidisipli-nary teamwork.

Key words from this definition include: ''design and management,'' ''hardware and software,'' ''structured, disciplined and documented,'' and ''overall integrated'' effort that involves ''multidisciplinary teamwork.'' These important notions will be reiterated and expanded upon in later parts of this book.

A third definition, formulated by this author, is that Systems Engineering is an [1.4]:

Iterative process of top-down synthesis, development, and operation of a real-world system that satisfies, in a near-optimal manner, the full range of requirements for the system.

Here, key ideas have to do with ''iterative,'' ''synthesis,'' ''operation,'' ''near-optimal,'' and ''satifies the system requirements.'' Designing and building a system usually involves several loops of iteration, for example, from synthesis to analysis, from concept to development, and from architecting to detailed design. The notion of synthesis is emphasized, since the essence of systems engineeering is viewed from the perspective of design rather than analysis. Design precedes analysis; if there is no coherent design, there is nothing to analyze. The term ''near-optimal'' suggests that large-scale systems engineering does not lead to a provably optimal design, except under very special circumstances. The normal cases all involve attempts to find an appropriate balance between a variety of desirable features. Trade-off analyses are utilized to move in the direction of a ''best possible'' design. Finally, in terms of the basic definition, we find a need to satisfy the full range of requirements for the system. The focus on constructing a system that is responsive to the needs of the user-customer is central to what systems engineering is all about.

The Defense Systems Management College text summarizes Systems Engineering as [1.5]:

An interdisciplinary engineering management process to evolve and verify an integrated, life cycle balanced set of system solutions that satisfy customer needs.

Here, key words emphasize a ''management process,'' ''verification,'' a ''balanced set of solutions,'' and ''customer needs.'' This definition, therefore, tends to see systems engineering through a ''management'' prism, requires a balanced set of solutions as well as verification of those solutions, and the satisfaction of what the customer states as a set of needs.

The last definition cited in this chapter is that represented by NASA, namely, that Systems Engineering is [1.6]:

A robust approach to the design, creation and operation of systems. NASA expands this short explanation by emphasizing:

1. Identification and quantification of goals

2. Creation of alternative system design concepts

3. Performance of design trades

4. Selection and implementation of the best design

5. Verification that the design is properly built and integrated

6. Post-implementation assessment of how well the system meets the stated goals

The above five definitions of systems engineering, in the aggregate, give us a point of departure for our further exploration of systems engineering and the management thereof. We will also see other representations that tend to add further detail and structure to these short-form definitions. For example, Chapter 2 cites several standards that relate to systems engineering. Further,

Chapter 7 defines the thirty elements that this author considers to be the essence of large-scale systems engineering.

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Project Management Made Easy

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