Page 147 - DCAP405_SOFTWARE_ENGINEERING

Software Engineering

Notes Some restraining factors that are considered to construct a system model are:
Assumptions that reduce number of possible permutations and variations thus enabling a
model to reflect the problem in a reasonable manner.

Simplifications that enable the model to be created in a timely manner.
Limitations that help to bound the system.
Constraints that will guide the manner in which the model is created and the approach
taken when the model is implemented.
Preferences that indicate the preferred architecture for all data, functions , and technology.
The resultant system model may call for a completely automated or semi automated or a non
automated solution.

Task System modeling is an important element of system engineering process. Analyze
how?

9.1.2 System Simulation

After some consideration regarding a meaningful way of putting System, Model, and Simulation
in an appropriate perspective I arrived at the following distinction.
System: A system exists and operates in time and space.
Model: A model is a simplified representation of a system at some particular point in time or
space intended to promote understanding of the real system.
Simulation: A simulation is the manipulation of a model in such a way that it operates on time
or space to compress it, thus enabling one to perceive the interactions that would not otherwise
be apparent because of their separation in time or space.
Modeling and Simulation is a discipline for developing a level of understanding of the interaction
of the parts of a system, and of the system as a whole. The level of understanding which may be
developed via this discipline is seldom achievable via any other discipline.
A system is understood to be an entity which maintains its existence through the interaction of
its parts. A model is a simplified representation of the actual system intended to promote
understanding. Whether a model is a good model or not depends on the extent to which it
promotes understanding. Since all models are simplifications of reality there is always a trade-
off as to what level of detail is included in the model. If too little detail is included in the model
one runs the risk of missing relevant interactions and the resultant model does not promote
understanding. If too much detail is included in the model the model may become overly
complicated and actually preclude the development of understanding. One simply cannot develop
all models in the context of the entire universe, of course unless you name is Carl Sagan.

A simulation generally refers to a computerized version of the model which is run over time to
study the implications of the defined interactions. Simulations are generally iterative in there
development. One develops a model, simulates it, learns from the simulation, revises the model,
and continues the iterations until an adequate level of understanding is developed.
Modeling and Simulation is a discipline, it is also very much an art form. One can learn about
riding a bicycle from reading a book. To really learn to ride a bicycle one must become actively
engaged with a bicycle. Modeling and Simulation follows much the same reality. You can learn

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