Research On The Navigation Risk Of Ships In The Traffic-intensive Waters Of The Yangtze River Estuary From The Perspective Of Vulnerability

Because of the characteristics of large transportation volume and low unit transportation cost,waterway transportation is conducive to promoting the economic development of the basin.However,due to the complicated water transportation operation environment,water traffic accidents often occurred,which puts higher requirements on the level of risk emergency control.In recent years,with the increase in the volume of goods traded on the water,the number of ships entering and leaving navigable waters through deep water channels has been increasing,and the cross-density of navigable ship routes has been expanding.If a sudden danger or accident occurs,due to many factors such as a large number of ships in a short period of time,intricate route crossings,and inconvenience in emergency rescue,it is very easy to cause water traffic congestion and navigation network disruption,which will lead to the vulnerability risk of the ship navigation system.Therefore,how to use appropriate models and methods to identify the vulnerability of the navigation system,describe the risk evolution mechanism,and analyze the two main risk scenarios of ship traffic congestion and emergencies is particularly urgent.The thesis is based on the theory of system theory,fragile system,water traffic safety,deep learning,complex network theory.The navigable risk of ships in depth and identifies the impact on ship navigation system were analyzed by combining with the specificity of traffic flow-intensive water area from the perspective of vulnerability in this work.The key vulnerability factors are divided into hierarchical structures and the risk evolution based on vulnerability factors.The ship traffic flow congestion and emergencies are analyzed as risk scenarios.An empirical analysis is carried out with the traffic waters in the Yangtze Estuary as the research background.These studies are intended to provide a theoretical basis for risk management and emergency safety of ship navigation systems.The main research content and innovative achievements of the paper include:(1)Divide the risk scenarios of ship navigation system in traffic-intensive waters from the perspective of vulnerability.Summarize the definition of vulnerability concept,vulnerability connotation,and vulnerability characteristic elements in different fields,comb the major events of vulnerability,and analyze the differences between vulnerability and the concepts of brittleness,anti-fragility,toughness,elasticity,robustness.On this basis,the concept of vulnerability of the ship's navigation system is defined.At the same time,combined with the characteristics of dense traffic flow waters,the risk scenarios of the ship navigation system are divided into ship congestion and unexpected events,and the risk scenarios are described.(2)The vulnerability factors of the ship navigation system are analyzed,and a vulnerability identification model is constructed.From the three perspectives of ship navigation system carrying capacity,environmental capability and control capability,three subsystems are divided.The vulnerability factors of the ship navigation system are determined.Comprehensive use of the advantages of decision-making test,evaluation experiment method and analytic hierarchy process,the vulnerability identification model was constructed.The degree of correlation between vulnerability factors and the overall influence matrix of vulnerability factors are obtained.The weight value of the vulnerability factor corrected by the entropy weight method was calculated.(3)Analyze the hierarchical relationship of vulnerability factors of ship navigation system,and construct a risk evolution model.On the basis of the factors affecting the vulnerability of the ship navigation system and their correlations,a hierarchical division method of vulnerability factors based on the explanatory structural model is proposed.The driving force and dependency of each vulnerability factor are analyzed in conjunction with the cross-effect matrix to generate vulnerabilities factor hierarchy diagram.Based on the selected critical vulnerability factors that affect the ship's navigation system,a risk evolution model of infectious disease dynamics based on vulnerability factors is constructed,and the impact of key vulnerable nodes on the risk evolution process is analyzed.(4)Aiming at the application scenarios of ship traffic congestion,a risk prediction model of ship traffic congestion is constructed.The characteristics of the main prediction parameters of the traffic flow and the cluster mapping relationship are analyzed,and the relationship is proposed to be mapped by the fuzzy mean clustering algorithm and the K nearest neighbor algorithm.The traffic flow prediction is constructed using convolutional neural networks,long and short-term memory networks,and support vector regression.The model realizes the prediction of ship traffic flow and density.On this basis,the cluster classification of traffic flow and density is completed,and the congestion risk level of ship traffic flow is finally obtained.(5)Aiming at the application scenarios of emergency risk in traffic-intensive waters from the perspective of vulnerability,the vulnerability measurement and risk evaluation model of navigation system are proposed.Using the origin mapping method,the network topology of the ship navigation system is constructed,and a vulnerability measurement model based on the complex network theory is constructed.Aiming at the different forms of attack or interference that the ship navigation system may be subjected to,the degree of change of the "fragile point" of the navigation system under the influence of the interference is analyzed.Measurement and risk assessment of vulnerable points in the navigation system.The research on the identification of vulnerability factors,vulnerability evolution,congestion risk prediction,and vulnerability measurement of the navigation system has enriched the theoretical research and technical application of ship navigation risk;based on the relevant data modeling and empirical analysis of ship navigation at the mouth of the Yangtze River characterization,the proposed vulnerability identification model can better identify the key vulnerability factors that affect the ship navigation system;the constructed risk evolution model based on the vulnerability factor of the ship navigation system can realize the hierarchical structure of the vulnerability factors and describe the vulnerability factors the law of risk evolution over time;the proposed ship traffic flow congestion risk prediction model can analyze the ship traffic flow congestion risk from the spatiotemporal perspective.The vulnerability measurement and risk evaluation method based on the complex network theory can achieve the key vulnerable nodes and the measurement of air routes and the realization of node risk assessment.The research results of the thesis attach important theoretical and social significance to the safety management of ship navigation and the improvement of the efficiency of ship transportation organization.