An object oriented/DEVS framework for strategic modelling and industry simulation

Ninios, Panagiotis (1994) An object oriented/DEVS framework for strategic modelling and industry simulation. Doctoral thesis, University of London: London Business School.

Abstract

The use of simulation modelling for the development of business strategy models, at an industry level, focusing on the exploration of different scenarios and future policy, has been gaining increased acceptance and popularity over the last decade.

This thesis develops a modelling and simulation framework for industry simulation, extending the approach of System Dynamics, by integrating recent concepts from software engineering and mathematical formalisms for discrete event system modelling.

The current modelling view of industry simulation, based on System Dynamics, is reviewed. A critique of the capabilities of System Dynamics is presented, regarding the ability of the System Dynamics core technology to address the broad requirements of industry modelling. We focus the critique and develop a research agenda around the issues of natural model building, model structure and focus, model reusability and time representation.

An overview of manufacturing simulation and the research directions in that area, is presented with the objective of identifying possible areas of cross-fertilization which can be used in modelling at the industry level in a more effective way.

A review of Object Orientation is presented, along with a general review of mathematical formalisms for the description of discrete event systems, with particular focus on the Discrete Event System Specification formalism (DEVS) [Zeigler (1976, 1984)]. An innovative synthesis of Object Orientation and DEVS is proposed in order to address the research questions which resulted from our critique of System Dynamics.

A Smalltalk implementation of the concepts supported by the synthesis, called OO/DEVS, has been developed. Using as a point of reference the requirements of industry simulation, we build upon a critique of previous DEVS implementations (placed within the manufacturing simulation problem domain), by presenting an innovative implementation view of DEVS, which exploits fully the concepts supported by Object Orientation.

The issues related to graphical model specification within OO/DEVS, and its comparison to the modem System Dynamics graphical user interfaces, are explored. A OO/DEVS Graphical User Interface and its implementation are explored and presented.

Two case studies have been employed, in order to test the capabilities of OO/DEVS as an alternative to System Dynamics, as well as to demonstrate the modelling characteristics of the framework and its implementation.

A comparative study is presented, where a capacity investment model of the postprivatised UK Electricity Industry is developed in both frameworks. The model is used as a vehicle for assessing the modelling characteristics of OO/DEVS versus System Dynamics. Our initial conclusion is that the modelling properties of OO/DEVS can address at a sufficient level the research issues related to the System Dynamics core technology.

Finally, a large scale modelling case study is carried out, within one of the UK Electricity Distribution companies, where a OO/DEVS model of the Electricity Markets is developed jointly with a management team. This real application establishes the value of OO/DEVS, and its modelling characteristics, as a powerful platform for building decision support industry models.