The International Association of Classification Societies has updated the North Atlantic wave scatter diagram and supplementary requirements. A series of ships, including bulk carriers, oil tankers, container ships, ore carriers, LNG carriers, PCTC ships and passenger ships, were used to analyse the influence of the updated wave scatter diagram on a ship's wave load through long-term wave load prediction. The results of the analysis show that, compared with the original North Atlantic wave scatter diagram, the new diagram and supplementary requirements have a different impact on different ship types, typically decreasing by 0~40%. The results of this study provide a reference for determining the extreme wave load of ships above the new scatter diagram.

Inland river navigation plays an important role in supporting the domestic and international dual circulation by connecting international and domestic markets. However, the navigable channels of inland waterways are limited. With the increased demand for inland vessel traffic and higher requirements for vessel traffic services, attention is increasingly being paid to the safety and efficiency of inland vessel traffic. It is necessary to rigorously explore the regularity and characteristics of inland vessel traffic flow and conduct research into traffic efficiency, safety and available channel capacity. Traffic flow simulation is one of the key methods employed in this type of research. By investigating and analysing the navigation behaviour characteristics of inland vessels, a cellular automata-based model of vessel traffic flow in inland waterways is established, and a simulation experiment is carried out based on a straight segment of the Yangtze River. The simulation results demonstrate that the model can accurately predict vessel behaviour, such as overtaking, entering and leaving waterways. The simulated traffic flow characteristics in trajectory simulations and spatial-temporal diagrams align closely with the actual situation. These results can provide theoretical and technical support for analysing inland waterway traffic flow, supervising vessel traffic, planning waterways, and forecasting traffic flow.

Ensuring the safety of ship navigation is fundamental to the high-quality development of waterway transportation. However, the complex and ever-changing nature of the navigation environment poses significant challenges to ensuring the safe passage of ships. The management of navigation safety risks is gradually shifting from passive measures, such as emergency response and post-accident analysis, to proactive risk prevention and decision-making. This paper analyses the current state of domestic and international research into the proactive control of ship navigation safety, as well as existing issues. It reviews key technologies and practical engineering applications in three areas: ship navigation information perception; ship-based navigation decision-making; and shore-based risk early warning. The paper proposes an integrated, intelligent and resilient approach to developing ship navigation safety controls, providing insights and technical references to enhance proactive control capabilities.

Optimising pilot scheduling can reduce working hours and labour costs for pilots, while offering new approaches to pilot training. This paper addresses the scheduling of pilots for inbound and outbound vessels in a one-way waterway by establishing a joint optimisation model, with the aim of minimising total vessel waiting time, total pilot working hours and labour costs. It proposes a two-stage heuristic algorithm that combines an imperialist competitive algorithm, an adaptive evolutionary strategy, and a variable neighbourhood search (VNS) algorithm. Case studies and comparative experiments demonstrate the effectiveness of the model and algorithm. Compared with the traditional first-come, first-served (FCFS) rule, the proposed approach reduces pilots' average working hours and labour costs by 17.4% and 12.4%, respectively. Therefore, integrating the model and algorithm into pilot training programmes or operational guidelines could enhance coordination among port departments, improve organisational efficiency and service quality, and support the development of green and smart ports.

This paper studied the problem of distributing commodities for RoRo ships. Taking into account the initial inventory level at each demand port, the paper proposes a flexible calling strategy for RoRo ships transporting commodity vehicles within multiple voyage planning periods. A collaborative optimization model for routing and stowage was established for RoRo ships, and an improved genetic algorithm was designed to solve it. The results of the numerical example demonstrate that this flexible calling strategy can reduce the total distribution cost of RoRo ships by 1.9%. There is a difference of about 4% in fuel consumption between large and small RoRo ships for round-trip voyages on the same route. Shipping companies can also reduce total costs by arranging different types of RoRo ship for distribution. When the safety stock is set to a moderate level, the total cost during the planning period is minimized. These research conclusions can provide a useful reference for shipping companies when making decisions about the distribution of commodities with RoRo ships.

In order to solve the problem of difficult control of rebound and large impact during the berthing process of vessels not under command, a variable throttling active buffer method is proposed. The principle of the variable throttling active buffer for vessels not under command has been designed. A mathematical model of the system is established. A simulation model of the system is built based on AMESim. The simulation results of the passive buffer system and the active variable throttle system are then compared. The effectiveness of the variable throttle active buffer system is verified. The main analysis focuses on the pressure in the variable throttle chamber, the displacement of the ship berthing buffer and the speed. The influence of the opening pressure of the variable throttle valve and the overflow valve on the performance of the active variable throttle buffer is studied. The results show that, when using the berthing variable throttle active buffer system, the vessel decelerates smoothly without rebound during the berthing process and there is no pressure impact or fluctuation in the variable throttle chamber. Increasing the variable throttle opening prolongs the pressure response time of the variable throttle chamber. Increasing the relief valve opening pressure prolongs the pressure attenuation time of the variable throttle chamber. Under low-normal speed or light load berthing conditions, the ship berthing buffer decelerates gently.

Qinzhou Port, one of the largest in the Beibu Gulf, had a throughput of over 170 million tonnes and a container throughput of more than 5.4 million TEUs in 2022. The port is currently considering adopting the "seamless-connection mode" scheduling strategy to improve the operational efficiency of container ships. However, quantitative analysis tools are lacking. Using AnyLogic simulation software, this study has created a simulation model of the entire process of arriving at the port, waiting at the anchorage, entering the channel, anchoring, and leaving the port, both under the 'seamless-connection mode' and the existing scheduling modes for container ships at Qinzhou Port. The simulation results show that, compared with the existing scheduling mode, the average waiting time for container ships is reduced by 50.7%, while the threshold value for harbour service ships can be increased by 19.5%. These results provide port authorities with the necessary theoretical and data-driven support to formulate relevant policies and traffic rules.

In order to improve the frequency stability of the ship shore power system, an improved Virtual Synchronous Generator (VSG) control strategy is proposed. Firstly, the effects of inertia and damping on frequency are analyzed through the small-signal model of the active power of VSG. Then, based on the transient processes of active power and angular frequency, the requirements for inertia and damping in different stages of the system's non-steady state are enumerated. This analysis is used to design a control method that enables inertia and damping to be adjusted adaptively with load changes, thereby effectively suppressing the fluctuation of shore power frequency. Simulation experiments show that, compared with the traditional VSG control with constant inertia and damping, the adaptive VSG control exhibits smaller overshoot, shorter adjustment time, and better adjustment accuracy for shore power frequency regulation. This approach effectively improves the system's frequency modulation (FM) characteristics and enhances the smoothness of active power transfer from shore power to ship power.

To solve the problems of complex decision-making and the difficulty of global optimisation involving many factors, this paper establishes a scheduling model for maritime search and rescue forces and uses a second-generation non-dominant genetic algorithm based on a reduplication strategy (DW-NSGA-Ⅱ) to solve these problems. Firstly, the probability of a successful search and survival (POSAS) is elaborated upon, taking into account the survival probability of the target and the relevant mathematical model of the time it takes the search and rescue force to arrive at the search area. A search and rescue force dispatch model is then established with the following optimisation goals: the maximum search success rate, the shortest arrival time of search and rescue materials, and the minimum search and rescue cost. Secondly, to solve the problems of crowding, distance failure, and poor global optimisation caused by multiple repeated solutions when solving the search and rescue force scheduling model using the second-generation non-dominant genetic algorithm (NSGA-Ⅱ), a second-generation non-dominant genetic algorithm based on a reduplication strategy (DW-NSGA-Ⅱ) is proposed. Finally, an accident is used as an example to demonstrate the use of DW-NSGA-Ⅱ and NSGA-Ⅱ to solve the model, with the resulting optimisation outcomes being compared. The experimental results show that the proposed method can consider marine environmental information, accident rescue requirements and search and rescue forces to formulate a reasonable and effective search and rescue force scheduling scheme. The DW-NSGA-Ⅱ algorithm's optimisation effect is better than that of the NSGA-Ⅱ algorithm under the same initial conditions, which verifies the superiority of DW-NSGA-Ⅱ in search and rescue force dispatch.

As the CII regulations took effect in 2023, shipping companies are under increasing pressure to comply with these stringent regulations. This paper presents a fleet optimization method for CII regulatory constraints, considering the difference in main engine fuel consumption performance within the fleet. Two scenarios are optimized: "Fleet scheduling considering single ship CII rating limits" and "Fleet scheduling with no E-class ships and the least used biofuel". The results demonstrate that the proposed optimization algorithm outperforms random scheduling in maintaining fleet CII compliance and reducing biofuel usage. This study will help shipping companies meet fleet CII regulations and reduce carbon emissions, while improving their ability to respond to international green and low-carbon regulations.