Ante Munitić

System dynamics continuous modelling of the ecological subsystem of the “Kastela Bay”

Abstract The Computer Simulation Submodel of The Ecological Regional Subsystem of the “KASTELA BAY” is an extra relevant submodel of The System Dynamics Computer Simulation Model of the “KASTELA BAY” which has been developed with the help of System Dynamics. It is, in its essence, a continuous model because it is presented as a system of non-linear differential equations. At the same time, it is a discrete model, because it is presented as a system of linear differential equations (System Dynamics DYNAMO-software package). Its DT (length of intervening time = computation interval) is chopped in full accordance with the Sampling Theorem [see Shannon, in: Systems modelling and analysis, I.J. Nagrath, M. Gopal (Eds.), Tata McGraw-Hill, New Delhi, 1984; see also Nyquist, McGraw-Hill Encyclopedia of Electronics and Computers, S.P. Parker (Ed.); and see Koteljnikov, Enciklopedȳa Kibernetiki, Akademȳa Nauk Ukrainskoi, Kiev, 1975]. The System Dynamics Computer Simulation Model of the “Kastela Bay” also employs certain experience gathered by experts who had worked on the preparation of projects: “Blue Plan” and “The Methodological Basis for the Scenario of the Management of Natural Resources of the ‘Kastela Bay’ ” (1991).

Simulatoin of behavior dynamics of management ship stability during changable regime of sailing

System Dynamic Simulating Modeling is one of the most appropriate and successful scientific dynamics modeling methods of the complex, non linear, natural, technical and organizational systems. The methodology of this method, together with use of digital computer, showed its efficiency in practice as very suitable means for solving the problems of management, of behavior, of sensibility, of flexibility of behavior dynamics of very complex systems. All this is made by computer simulating, i.e. “in laboratory”, which mean without any danger for observed realities. The paper deals with dynamic analysis of automatic ship steering gear systems utilizing complex controls that function according to the principle of proportional, integral and derivation regulators. The analysis involves a system dynamic simulation modeling methodology as one of the most suitable and effective means of dynamic modeling of complex non-linear, natural, organizational and technical systems. The paper discusses system dynamics simulation models being used in qualitative (mental-verbal, structural) and quantitative (mathematical and computer) simulation models on ships equipped with trailing steering systems and PID regulator. Authors suggest using the presented models for designing and constructing new steering systems, for diagnosing existing constructions and for education in Universities.