Research On Dynamic Risk Pre-assessment For Maritime Traffic Safety In Heavy Weather

In order to solve the two key problems of vessels sailing in heavy weather condition,such as "whether a vessel can sail safely" and "how to sail safely",a dynamic risk pre-assessment system(hereinafter referred as The System)is established for maritime traffic in heavy weather in this doctoral dissertation.Based on the functions and algorithm as designed on the said purpose,The System is able to dynamically indicate the risk level of a certain vessel in a specific sea area or route in the near future,and meanwhile to provide shipmaster and the relevant personnel with a visual and intelligent warning supervision over the vessel for the assistance of decision-making.The main research works are stated as follows:Firstly,from a more applicable and reasonable perspective,three types of mathematical models for maritime traffic risk pre-assessment in heavy weather condition are established by using the fuzzy comprehensive evaluation method for giving prominence to the dynamics of marine environment and the monitor of certain vessels.On the basis of large number of sample data,for example,a risk matrix of the maritime traffic in the weather condition of restricted visibility is established by using the expert investigation method modified through the theory of fuzzy information distribution under the condition of incomplete information.The results of comparison and analysis show that the modified risk matrix can avoid the shortcomings of the expert investigation methods that rely entirely on subjective judgement by reflecting the characteristics of maritime traffic risk and the situation of the risk in practice,and thus can improve the accuracy and reliability of maritime traffic risk assessment.These mathematical models and the risk matrix can be used as a theoretical basement for the visualization and intelligence of such decision-making assistance as the pre-warning supervision of the maritime traffic risk in a heavy weather condition.Secondly,the Advanced Regional Prediction Data Analysis System-Weather Research and Forecast(ADAS-WRF)numerical weather prediction mode system and other modern meteorological technologies are applied to grid the data provided by relevant authorities from the two angles of temporal sequence and spatial sequence.Then,the theory of extreme learning machine scheme in artificial neural network is employed to forecast the traffic flow density of vessels for a short time in future.The results of date analysis and simulation show that the technology of data prediction and processing is able to realize the function of a stable,accurate,fast risk dynamic information date rolling continuous prediction and processing under the input of the forecasting data of the wind and wave at the time interval of 1 h and the space grids of 10 km x 10 km,the forecasting data of visibility at the time interval of 1 h and the space grids of 2 n mile x 2 n mile,and the forecasting data of sea ice at the time interval of 12 h and the space grids of 10 n mile x 10 n mile,and the forecasting date of the traffic flow density of vessels at the time interval of 10 min and the space grids of 2 n mile x 2 n mile.Subsequently,a reliable support of technology and data for the visualization and intelligence of the decision-making assistance mentioned in The System is achieved.Finally,by combining the dynamic pre-assessment model of the maritime traffic risk,the data processing technology of meteorological forecast information,the theory of traffic flow density prediction,and the information platform of Automatic Identification System(AIS)of vessels,three types of The System for the visualization and intelligence of the decision-making assistance in different heavy weather conditions are designed and realized.The example simulation results show that the three types of The System realize the dynamic risk pre-assessment of a certain vessel in a specific sea area or route,and also realize the visual and intelligent warning supervision over the vessel for the assistance of decision-making to avoid major maritime traffic risk,and the calculated risk level is basically consistent with actual risk level.The results verify the effectiveness and reliability of The System.The three types of The System improve the visualization and intelligence of the pre-assessment of maritime traffic risk under rough weather condition,and enrich the research of the pre-assessment of marine traffic risk in the weather condition of restricted visibility and heavy sea ice,have a certain theoretical significance and a wide range of practical application.Through the above-mentioned research work on the dynamic risk pre-assessment for maritime traffic safety in heavy weather,this paper basically solves the key problems for vessels of "can or cannot sail safely" and "how to sail safely" in heavy weather in the future for a period of time.The above research results in this doctoral dissertation show that The System for maritime traffic safety in heavy weather should not only make full use of modern mathematical theory and latest technology to guide and correct the specific work practice of maritime traffic risk assessment,but also consider the worst-case of the dynamic environmental factors.The research results can be used to provide a reference for maritime safety administration in maritime affairs to develop the regulations,code and guidelines for marine traffic safety in heavy weather condition,and implement maritime traffic control behaviors and vessel traffic service.At the same time,it can be used to propose a technical means for shipping companies to establish and improve the vessel navigation safety management system,and track and supervise the vessel dynamics,and also used to offer practical guidance for the voyagers such as the captain,officer on watch and the pilot to drive and maneuver the vessel safely.