SIMULATION MODEL OF THE FUNCTIONING OF THE LOGISTICS SYSTEM FOR THE SUPPLY OF GRAIN CARGOES FROM UKRAINE TO THE COUNTRIES OF THE WORLD

The article analyses the existing developments in the logistics of grain and similar cargoes in international systems. Due to the increase in logistics costs, Ukrainian agricultural companies receive a lower price compared to world market prices - they have to bear the costs caused by an inefficient logistics system. Therefore, it is necessary to develop a simulation model of the logistics system for the supply of grain cargo from the producer to the seaport of departure, as the main hub of communication with ports around the world. And the modelling will allow us to determine the level of influence of the obtained data on the transport material flow on the efficiency of decision-making. It is proposed to build models based on Petri nets, which allow to study the behaviour of an object in real time by assessing the performance of the system without forecast data. Today, the logistics system of grain cargo delivery in Ukraine has a structure based on the interaction of participants: agricultural companies as producers and organisers of grain exports, farmers, transport and logistics companies, as well as the existing infrastructure of Ukrainian and foreign ports, railways, and roads. This principle of interaction allowed us to build a structural model of functional interaction in the grain supply system. Based on this interaction and the principles of organising the supply of grain cargoes from production (harvesting) to the port of departure, a two-tier model of the functioning of this logistics system was developed. At the top are models of data collection and processing by an agricultural company, and at the bottom is a simulation model of the logistics system. A simulation model of grain cargo movement from the sender to the seaport of departure based on Petri nets has been built, which reflects the structure of relationships between the elements of the system and the dynamics of changes in its states in a compact form. On the basis of the built model, a simulation was carried out for three variants of distribution of cargo flow by two modes of transport. It has been determined that the option of uniform distribution of grain cargo between road and rail transport allows to save time.