A New Method for Modeling System Dynamics by Fuzzy Logic: Modeling of Research and Development in the National System of Innovation

System Dynamics (SD) is an effective method for studying dynamic conditions and changes in complex systems. It has been used in domain of social, economic and human activities which deal with vague and inaccurate variables. In this paper, a new dynamic model of real world systems is designed based on the concept of system dynamic approach. Then relations among the variables in the model are defined as fuzzy if-then rules by using fuzzy logic method. For analyzing the model accurately and avoiding the extent of ambiguities, Fuzzy Inference System (FIS) will be designed. For this purpose, cycle of creation and absorption of knowledge in a National Innovation System has been analyzed via SD methodology and FIS results.