The shell structure is developed for the Undersea Data Center to isolate it from seawater and dissipate the heat generated by the data center.With the help of gasbags and a gantry crane the shell can bring the data center up for routine service.In emergency,the shell itself can bring the data center up to sea surface.The shell structure is optimized for high heat dissipation efficiency and comfortable working condition.Simulations are conducted to examine the performances of the shell,including the surface stress of the shell,deformations under various working conditions and total heat dissipation.
The attributes of the spatial distribution(ship type,ship position,ship speed,traffic density)and the time characteristics(traffic change against time,daily traffic change)of the traffic flow in Tiaozhoumen Channel is studied by means of local density and mathematical statistics.The research shows the following facts:The geographic position of docks and main channel decide the traffic distribution,and ships are highly concentrated in deeper water area;The number of larger ships in a day is twice to three times of that of smaller ships;69.35%of larger ships are cargo ships and smaller ships are mostly workboats,accounting for 40.34%;The ships in the channel usually sail at medium or low speed,especially cargo ships and tanks;Container ships,workboats and passenger ships may sail at higher speed;Small ships usually follow the rule of"to start work when the sun rises and to stop work when the sun sets",so the number of small ships in the channel changes significantly over time of the day.In the contrary,the number of larger ships does not change too much in a day.
The Traffic Congestion Index(TCI)for ports is introduced and the modeling and calculation of the index is conducted based on AIS data.The experience on road traffic is used to develop the index system.In order to establish TCI,the VTS reporting line of the port is moved outwards to ensure the AIS reporting zone to cover all roadsteads.The time of every ship's entering the port,staying at berth and leaving the port are respectively calculated according to AIS data.The ratio of actual in-port time of ships to in-port time reference is defined as the indicator of port congestion.The time ratio for each ship is weighted according to its cargo type and ship length.The weighted time ratios for ships are combined to get the TCI of the port.Tianjin Port,Shenzhen Port and Ningbo Zhoushan Port are examined with the TCI for illustration.
A model involving ship's turning characteristics is developed to improve the accuracy of distance-to-new-course calculation.The conventional calculation method based on ship maneuverability indices K-T and its limitations are analyzed.The ship's motion characteristics and the relations among the parameters are studied.The design rules relating to channel bending radius and the impact of bridge position on a ship are introduced into the model for calculating distance-to-new-course.The model has been used for several ships and proved.
The influencing factors of risks that associated with piloting a ship in port are analyzed and their unascertained measurement model of the factors are identified.Copula function is used to weigh the risk factors and a risk assessment model involving the factors with uncertainty is built.Particularly,the process of piloting a ship through the Pearl River Estuary is quantitatively studied through analyzing several scenarios.Relatively significant situation features of pilotage operation are identified and risk assessment is conducted.The results are examined against practical pilotage processes and proved.The research shows that the risk level in middle-late stages of piloting a ship through the pearl river estuary is medium and tide is the critical factor influencing the risk situation.
