Study On Ship Following Model In Arctic Ice Area

With the continuous melting of the Arctic sea ice,it is possible to open the Arctic to navigation.Many shipping companies are eager to strive for more potential economic benefits on this "golden waterway" in Asia and Europe.However,the rather complex sea ice situation increases the risk of ice navigation.How to ensure the safety of ship navigation while pursuing interests has always been the primary issue in ice navigation.At the same time,when the Arctic shipping is gradually normalized,the number of ships sailing in the Arctic continues to increase,accompanied by a large number of ship exhaust emissions and an increasingly fragile Arctic environment,the Arctic region will face great challenges in environmental protection.In this regard,this thesis first analyzes the ice following characteristics of ships on the Northeast route from two aspects: the ice navigation mode and the feasibility of green economy.Secondly,based on the vehicle following theory,three ice following scenarios are designed according to the ship ice resistance in different ice breaking channels,and the ship safety following model is constructed.Finally,based on the consideration of navigation cost,navigation time and fuel emissions,a multi-objective programming model of green economic ship following is constructed,and it is solved by using NSGA II and MOPSO algorithm.Finally,taking the Northeast route of the first voyage of "Tian you" in 2018 as an example,the simulation was carried out for the following behavior of the ship when sailing in the ice area,to explore the best speed and following distance under different ice sections,so as to provide a safe,green and economic decision-making scheme for shipping enterprises to actively participate in the development and construction of the Arctic route.By analyzing the simulation results of "Tian you" ship following model,it can be found that:(1)When a ship navigates in the ice area,it is very easy to be affected by the sea ice movement.The ship speed will be adjusted with the change of navigation resistance,and the change of ice breaking resistance is the key to the smooth navigation of the ship in the ice area.The results show that the variation of ice breaking resistance is closely related to the sea ice density and the sea ice thickness.With the increase of sea ice density,the ship ice breaking resistance increases significantly,showing a significant positive correlation;The sea ice thickness has a certain sensitive range to the change of ice breaking resistance,and the sea ice with a thickness of 0.3-0.5m has the most obvious effect on ice breaking resistance.(2)According to the distribution of broken ice on the follow-up channel,the more serious the ice condition on the follow-up channel,the smaller the safety speed between ships.When the ship is sailing in the general following scenario,the following safe speed shall be maintained at 6.5-7.5m\/s;If the ice condition is extremely serious and the ship is in an extreme following scenario,the safe speed of ship following needs to be controlled within 2-3m\/s.(3)The more serious the ice condition on the follow-up channel,the smaller the safety distance between ships.When the speed is lower than 6kn,the safe distance between ships in any follow-up scenario should be kept within 500-600 m as far as possible.If the front ship fails to break the ice smoothly in case of emergency,the pilot of the rear ship shall complete the speed adjustment within 50 meters after realizing the need to adjust the navigation state,otherwise there will be a risk of collision.(4)The speed optimization results of "Tian you" ice navigation show that within the range of safe following behavior,the following speed can be improved by 25% and the following distance can be shortened to 4% of the original distance.If IFO is used as fuel and equipped with good exhaust gas washing device during ice navigation,the following mode is expected to achieve the overall optimization in economy,exhaust gas emission and navigation time in the future.Therefore,this conclusion has certain reference value for the actual Arctic route ship ice navigation decision-making.