The heart of modelling is formed by three aspects: the decomposition of a system into interrelated subsystems, called components here, the classification of these components and relations, and the representation of the resulting model. Modelling support (i.e. computer tools) should provide means for utilising powerful decomposition, classification and representation concepts, such as those incorporated in bond graphs for example. In this paper, an analysis is presented of techniques which (partially) enable the implementation of these concepts in computer-based modelling tools. The first and oldest technique applied as such is typing, which enabled the encapsulation and parametrisation of components and hierarchical modelling. This improved decomposition and classification possibilities of modelling support. Secondly port based interfaces have been incorporated in modelling tools. Such interfaces made it possible to model with an object oriented approach instead of a process oriented one, and improved the representation of models by enabling a component to be depicted as a network of lower level components. It is shown that typing and port based interfaces together allow the decomposition and its representation as done in bond graph modelling, but they do not support classification properly. The use of inheritance by means of subtyping improves this, but leads to components that can not be instantiated. To solve this, it is proposed to use the technique of modularisation. In modelling tools, modularisation involves the division of component definitions into two parts: a type, defining essential properties of a component, and a specification, defining the incidental ones. One type may have more than one specification, i.e. component types become polymorphic. Modularisation can, in combination with subtyping, support classification, and therefore it is said to extend hierarchical modelling into polymorphic modelling. An implementation in a modelling system is presented and examples are shown which demonstrate features of a polymorphic modelling system.
|Conference||International Conference on Bond Graph Modeling and Simulation, ICBGM 1993|
|Period||17/01/93 → 20/01/93|