SIMULATIONS OF PRODUCTION-DELIVERY MODELS USING CONVENTIONAL METHODS OF DYNAMIC SYSTEMS: ZELGRAF COMPANY AS A CASE STUDY

The article presents the subsequent steps in developing a simulation model of the production-delivery system in a manufacturing company. Initially, the essence of the production-delivery process, namely all key processes that constitute the core business of a manufacturing company was explained. The most important decision principles directly related to these processes were identified and briefly characterized. This was followed by a presentation of the business profile of Zelgraf manufacturing company, where tests aimed at a practical understanding of the processes were carried out. This knowledge was useful in selecting variables of the mental model related to production-delivery processes, which are presented in tabular forms. The variables of the mental model, linked in a cause-effect diagram formed the basis for designing the simulation model.
A target simulation model was developed relying on the cause-effect relationship diagram. This involved the application of the method of dynamic systems. The Vensim^® DSS software was made use of both in designing the model and simulation. The different definitions of variables and the constant values for the model were provided using the programming language. These values were the direct outcome of empirical studies conducted in a given company. This was followed by the validation of the simulation model based on three methods. The last stage involved conducting a simulation of the model for an adopted stage, the presentation of the path of the
accumulatory variables, including chosen variables of the system and finally an analysis of the results obtained was conducted. Possible practical applications of the designed model were
mentioned in the conclusion.

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