COMPONENT-BASED COMPOSITION OF SYSTEM DYNAMICS MODELS

An approach using component technology for the development of System Dynamics models is introduced. At first a brief introduction of System Dynamics and its modeling elements is given. The representation of System Dynamics models in Vensim, an interactive software environment for the handling of such models, is described. On this basis the paper provides a concept for component development and model composition. The concept is basic and independent from any problem or domain specific context. An example depicts the appliance of the concept to a given problem domain explaining the usage of domain specific model design patterns and components. Finally a prototype system to support component-based modeling is described. PROBLEM The use of component-based approaches lead to vast improvements in almost every engineering discipline. The list of success stories ranges from classical Indus-trial production to software development and service manufacturing. The advantages of component technolo-gy are well-known. Examples are increased reusability, reduction of complexity, encapsulation of expert know-ledge, accelerated production, and the establishment of quality standards. This paper introduces a concept for the component-based development of System Dynamics models and outlines the potential, that the adoption of component technology can bring to the field of System Dynamics modeling. So far, only few work has been done in this area (Eberlein 1996; Myrtveit 2000; Tignor 2001). Therefore, concepts for modeling components and soft-ware environments that support the component-based model composition are rare. The paper starts with a brief introduction of System Dynamics in general in order to sketch the requirements for the conceptualization of a component-based mode-ling approach. As the software environment Vensim is used for implementation, its specific representation of System Dynamics is outlined. After that the modeling concept and a prototype system supporting the composi-tion process are described