Research On Calculation And Regularity Of Ship Density Based On AIS Data

Ship density can directly reflect the state of marine traffic,and it is the key content of marine traffic investigation.It is of great significance to explore the distribution law of vessel density in the water area and to provide theoretical support for the Maritime Traffic Control Department to formulate reasonable maritime traffic control activities.USING AIS data to calculate ship density overcomes the problem of poor timeliness of traditional marine traffic survey methods,but because of the periodicity of AIS data dissemination,the calculation of ship density is related to sampling time,the calculation result of instantaneous ship density is not accurate and the calculation efficiency is low.Therefore,it is very urgent and necessary to study an accurate and fast ship density calculation method based on AIS data.In this paper,the ship density calculation model is established with AIS data,and the ship density distribution law is explored.Firstly,a grid-based method for AIS data storage is proposed,which maps AIS trajectory data into each grid by gridding the research area,and obtains the time of ships entering the grid and the time of stay in the grid.Then,the paper analyzes the connotation of instantaneous ship density and average ship density,considers the effect of ship size on traffic safety,and establishes a ship density calculation model based on standard ship.Finally,the hourly mean ship density is used as a random variable,and the non-parametric kernel density estimation method is used to estimate the probability density function.Taking the AIS data of Tianjin Port as the research object,the storage space of the grid-based AIS data is 64%less than that of the original data,and the ship density based on the standard ship is obtained by using the ship conversion coefficient,the GAUSS kernel function is selected to determine the optimal bandwidth,and the ship density in the waters of the Port of Tianjin Channel,Anchorage and port area is estimated,and the statistical characteristics of the ship density are calculated,the density of ships in the harbor basin is large,the dispersion is high and the probability density curve is sharp and steep,but the density of ships in the Anchorage and channel is relatively small,the density of ships is relatively uniform and the probability density curve is relatively flat.The experimental results show that the ship density calculation model based on the standard ship can reflect the influence of ship size on the ship traffic safety,the Distribution Law of ship density can be obtained by the probability density curve and other statistical features.The research results can provide data support and theory support for safety supervision and macro-traffic evaluation of maritime department.