System dynamics and discrete event simulation modelling.
This thesis investigates the relationship between discrete event and system
dynamics simulation modelling. Each modelling technique has its own strengths and
limitations. The choice of using one particular modelling technique often depends on
the preference and the knowledge of the modeller rather than on the nature of the
problem. The basis of this research has been to address the problem from a different
perspective. This has been to look at the nature of the problem first, and then determine
the most appropriate modelling technique to apply.
The basic method adopted was to compare, contrast and experiment with
these two modelling techniques in order to determine a number of common and
unrelated concepts between them. This investigation discovered that a system
dynamics flow diagram could be used to represent an activity cycle diagram of a
discrete event model. The converted flow diagram can provide a different viewpoint
from the discrete event model due to the feedback characteristic of system dynamics.
This research went on to develop a set of guidelines to convert an activity
cycle diagram into a system dynamics flow diagram. Experimentation with many
examples demonstrates that these conversion guidelines provide a consistent and
systematic method for obtaining a system dynamics flow diagram.
The final stage of this research was to develop a prototype computer system
(SMCP) to demonstrate these guidelines. SMCP consists of two modules, the ACD
module which allows the user to specify a discrete event model through textual
descriptions, and the SD module which allows the user to build a system dynamics
model by drawing symbols and using text inputs. In addition, SMCP allows users to
convert an ACD to a system dynamics flow diagram quickly and easy, and also
demonstrates the concept of data sharing.