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.
Conventional method has not been successful in predicting cargo throughput of ports due to the great fluctuation caused by complex external factors.In order to improve the accuracy of cargo throughput prediction for ports,the combination of NeuralProphet time series model and LSMT neural network is introduced.NeuralProphet model is trained to produce,according to input cargo throughput data,a preliminary prediction with a residual sequence.The LSMT model is used to correct the preliminary prediction and output final prediction.The combination model is verified through process the monthly throughput data from Shanghai Port and Xiamen Port.The advantage of the combination model in handling abnormal fluctuation over other configurations is demonstrated.
A ship,especially a larger one,has to take an appropriate start position in a river to smoothly travel through a river bend.That start position has been chosen according to experience gained in long navigation practice.A pithy formular"taking higher side and aiming for lower side"has been the general guidance.This paper quantitatively analyzes the process of ship travelling through a river bend and develops a method to calculate the position where a ship starts to sail through a river bend according to actual water flow in the river.A positioning model is built based on ship motion process and the ship lateral displacement and track width are calculated against the yaw angle and transverse flow by means of Matlab.The position the ship should take before starting to travel through a river bend is decided based on the calculation results.The calculation for Yingongzhou curved waterway is checked through simulation and proved.
A dual-objective multi-cargo inland port deployment optimization model is built.One of the objectives is minimum overall costs for construction,operation,transport,transit and time,and the other is minimum pollutant emissions.Three algorithms are designed:conventional genetic algorithm;the combination of genetic algorithm and simulated annealing algorithm;and the non-dominated sorting-based genetic algorithm.For verification,the deployment planning is tried for tree provinces in northeast China and the eastern cities of Inner Mongolia with the model.The finding of the experiment is cited that when the time sensitive factor of the cargo is low,larger part of the cargo goes to seaports to be shipped to destination via inland ports,while if the time sensitive factor of the cargo goes higher,more cargo will go to seaports by highway.
A fault prediction method for shafting of main engine is developed based on shaft vibration monitoring.Ensemble Empirical Mode Decomposition(EEMD)and Enhanced Intermittent Unknown Input Kalman Filter(EIIKF)are introduced into the fault prediction method.The vibration signal is mixed with a white noise before decomposition to prevent the modal mixing and improve the decomposability.The vibration signal,after filtering and reconstruction,is processed by sequential analysis to get the characteristic curve of the signal.EIIKF is used to analyze the characteristic curve and do working status prediction.In this processing,by introducing intermittent parameters,the uncertainty caused by some unknown input items is compensated.Fault diagnosis is carried out by checking the working status against a fault discrimination model.The method is verified with actual data from engine operation.The fault prediction capability of the method is seen better than that of conventional mode decomposition and Kalman filtering in terms of accuracy and timeliness.
For feeder container ship transportation with the characteristics of changeable feeding ports and variation of berthing conditions at ports,a two-stage method is applied to jointly optimizing route planning and cargo stowage of the feeder container ships.With the constraints of ship capacity,ship stability and cargo delivery time,a MIP(Mixed Integer Programming)model is constructed for the objective of minimizing the total operating cost of the container fleet and minimizing the number of mixed stacks.A PSO(Particle Swarm Optimization)algorithm is designed to solve the problem.Several practical cases are calculated to demonstrate the efficiency difference between direct model calculation and the PSO algorithm.For larger scale problems,the solution time for model direct calculation exceeds 600 s,while with PSO,the maximum solution time is 16.66 s and the average solution time is 10.00 s.Which can provide reference for practical optimization of feeder container ship transportation.
The track prediction in junction with improved velocity obstacle is combined introduced into dynamic intelligent collision avoidance calculation to accomplish the intelligent collision avoidance in restrained waterways.The model of relative motion between two ships is built and the collision avoidance motion parameters of the ships are calculated in real time.The motion states of OS(Own Ship)and the TS(Target Ship)at subsequent moment are predicted by using the 3D MMG(Maneuvering Modeling Group)model and Kalman filtering.The above process in conjunction with rules of Convention on the International Regulations for Preventing Collisions at Sea and good seamanship altogether form the complete dynamic intelligent avoidance algorithm.The algorithm is verified through simulations.
The high-performance metal additive manufacturing has been an answer to ultra-large structure manufacturing demanded by ship building industry,which is building increasingly bigger ships.The additive manufacturing of the skeg end structure is studied.A scale reduced structure is made by means of additive manufacturing.According to the specifications,the chemical composition of the material is analyzed and the non-destructive testing and tests for mechanical properties of the material is carried out.All that proves the feasibility of the application of metal additive manufacturing in ship building.The structure is further,optimized which made the structure 8%lighter while keeping the structure strength and modes satisfying the specification.
In order to promote the construction of green ports in China and achieve the carbon peaking and carbon neutrality goals,the State Council,ministries and commissions and local governments have issued 32 policy documents respectively to accelerate the use of shore power for ships.The paper analyzes the contents of the documents and builds a policy consistency index model.The model divides the shore-to-ship power policy into three kinds:mandatory,subsidy,and guidance and environment.Two of each kind of the documents are selected to be examined.The empirical analysis of the rationality of the documents are performed.The research shows that the policy documents can be improved in three ways:at the state level,the central government should focus its effort on mandatory rules rather than subsidy polices and guidance instructions;at the regional level,the local authorities should follow the state policy and direct the development of shore-to-ship powering in general;the coverage and coordination of relevant departments and enterprises should be monitored to ensure a network of full coverage without overlapping.
The safety evaluation criterion for fire escaping is set up.The professional fire simulation software PyroSim is used to simulate the engine room fire on a deep-sea fishing vessel and to find the ASET(Available Safe Egress Time).Personnel emergency evacuation software Pathfinder is used to optimize the feasibility and effectiveness of escape path and calculate RSET(Required Safe Egress Time).Comparison between ASET and RSET tells whether the crewmembers can escape safely.Practical calculation shows that the former is 154 s and the latter can be 144 s if an inclined ladder is added,which means that the crew members can be safely evacuated from engine room on fire as long as things are right.
It is very likely that the Arctic Route to develop into an important Asia-Europe cargo transport route.The implication of this fact should be investigated.For doing so,the container trade goods are divided into four categories through systematic clustering;a distribution models of cost flow network is built based on the time value of goods.The effects of initial value,depreciation rate and transportation time of goods on the distribution situation of the Northeast passage is studied.The study shows that,compared with traditional routes,the Northeast passage has the advantage of shorter transport mileage and less time;the proportion of cargo distributed to this route is more than 50％ as for higher vale or time sensitive goods are concerned;if the traditional route is congested,the distribution rate to the Northeast passage can even as high as 70％ or more.The potential for development is huge.To strengthen strategic cooperation with Artic countries and encourage shipping companies to try the Arctic route are suggested.
There are reports about container terminal construction or development of related technologies in China sometimes on TV,however,a comprehensive review of the development in the field will give a deeper understanding of the field.This paper investigates the documents published on CNKI and reviews the documents belong to topic Container Terminal by means of the topic model.The thesis published after 1992 are analyzed and the development in past 30 years are explored and the hot spot of R&D and the leading edge of technology development are presented.The work intensity-time distribution of 16 research topics is studied showing 6 of them going up and 3 of them going down,which is a good representation of current situation.
The documents concerning the calculation of conversion coefficients for marine fuels are reviewed to see the rationality of the conversion coefficients given by IMO.The method of calculating the coefficients is analyzed.Inconsistency in given atomic weight approximations for carbon,hydrogen and oxygen is found.Besides,the fundamental data source is not up to date.These problems are degrading the accuracy of carbon emission calculations.The corrections for the conversion coefficients are proposed.The conversion coefficients for ethane and bio-gasoline/biodiesel are calculated.A proposal on timely revising the conversion coefficients is prepared.Prudent treatment is suggested in using the conversion coefficients given by IMO to evaluating domestic emissions.
An analysis method to evaluate a large cruise ship's capacity for traveling home is developed in order to replace complicated and time-consuming physical tests.Existing records of fire accidents on large cruise ships are studied and an evaluation index system for mobility evaluation is built.The index system comprehensively reflects the situation of the fire site,seaworthiness of the ship,crew competence and other factors.The weights for the factors are decided by means of AHP(Analytic Hierarchy Process)and the evaluation result is derived through fuzzy calculation.A 135 000 ton cruise ship is examined to demonstrate the evaluation process.The evaluation shows the good traveling-home capacity of the ship in case a fire happens.
A collision avoidance path planning model is developed based on Adaptive step Rapidly-exploring Random Tree(Ada-RRT)algorithm instead of conventional RRT.The latter may experience low sampling efficiency in complex environments.The ship domain model is introduced to guarantee safety.Virtual obstacles are generated to ensure that the planned path complies with COLREGs.The time series is introduced to establish a dynamic obstacle detection mechanism.Heuristic sampling strategy is adopted to prevent the generation of invalid nodes.The mapping function between obstacle density and RRT searching step size is established.With the linear dynamic model,the preliminary current searching step size is calculated according to the previous searching step size.The preliminary step size is optimized according to the obstacle density information.Simulation is carried out.The results show that,compared with the conventional RRT model,the ship collision avoidance path planning model using Ada-RRT algorithm performs is superior in four aspects:sampling success rate,path searching time,number of path segments and total length of path.
Scenario planning and stochastic programming is introduced into the location selection of maritime rescue base and the optimization of rescue ship configuration.Several types of rescue ships and their respective seaworthy areas are investigated.Three severe weather scenarios are assumed.A two-stage stochastic programming model is built and the immune PSO(Particle Swarm Optimization)algorithm is developed.The method is verified with South China Sea case.The sensitivity analysis for the results is carried out.The result shows that the method can provide optimum proposals in saving rescue costs.
