Page 297 - Mechanical Engineers' Handbook (Volume 2)

288 Analysis, Design, and Information Processing

5.3 The Development of Aids for the Systems Design Process
This section describes five important phases in the development of systems and systemic
aids for the design process. These phases serve as a guide not only for the sound design and
development of systems and systemic aids for design decision support but also for their
evaluation and ultimate operational deployment:

• Requirements specification
• Preliminary conceptual design and architecting
• Detailed design, integration, testing, and implementation
• Evaluation (and potential modification)
• Operational deployment
These five phases are applicable to design in general. Although the five phases will be
described as if they are to be sequenced in a chronological fashion, sound design practice
will generally necessitate iteration and feedback from a given phase to earlier phases.

Requirements Specification Phase
The requirements specification phase has as its goal the detailed definition of those needs,
activities, and objectives to be fulfilled or achieved by the system or process that is to result
from the system design effort. Furthermore, the effort in this phase should result in a de-
scription of preliminary conceptual design considerations appropriate for the next phase. This
must be accomplished in order to translate operational deployment needs, activities, and
objectives into requirements specifications if, for example, that is the phase of the systems
engineering design effort under consideration.
Among the many objectives of the requirements specifications phase of systems engi-
neering are the following:
1. To define the problem to be solved, or range of problems to be solved, or issue to
be resolved or ameliorated, including identification of needs, constraints, alterables,
and stakeholder groups associated with operational deployment of the system or the
systemic process
2. To determine objectives for operational system or the operational aids for planning,
design, and decision support
3. To obtain commitment for prototype design of a system or systemic process aid
from user group and management
4. To search the literature and seek other expert opinions concerning the approach that
is most appropriate for the particular situation extant
5. To determine the estimated frequency and extent of need for the system or the
systemic process
6. To determine the possible need to modify the system or the systemic process to
meet changed requirements
7. To determine the degree and type of accuracy expected from the system or systemic
process
8. To estimate expected effectiveness improvement or benefits due to the use of the
system or systemic process
9. To estimate the expected costs of using the system or systemic process, including
design and development costs, operational costs, and maintenance costs