Designing Complex Systems

56 n Designing Complex Systems

We note that while a service is always an “output” as far as a functional element

is concerned (in the sense of presenting the capability to the user), the functional

parameter may actually describe an input to the physical object. As an example,

consider a garbage disposal plant (e.g., incinerator). Its functionality is to dispose

of garbage; this is the service it provides to the users (the community). It is a func-

tional output, and its capability for disposing of garbage is the associated functional

parameter, even though the physical flow of garbage is into the plant. Another

example is a user command; the signal flow is into the equipment, but the equip-

ment has the capability of sensing the user’s comm ...