The Western-Pacific region contains abundant polymetallic nodule resources. Effectively exploiting these resources is of great significance for the metal resources supply in China. To verify the feasibility of deep-sea mining and achieve commercial mining, it is necessary to conduct in-situ sea trials of the mining system in the mining area and develop environmental monitoring procedures to assess the impact of the mining operations on the environment. This study focuses on the monitoring content and monitoring plans by establishing a set of environmental monitoring and impact assessment procedures. It details the environmental monitoring procedures for sea trials across pre-trial, in-progress, and post-trial phases. The results show that polymetallic nodule mining is feasible in the Western-Pacific region. However, the impacts of mining plumes and sediments on the bottom marine ecosystem should be considered carefully, alongside the formulation of effective mitigation measures.

To address the influence of multi-scale complex loads on the deep-sea mining transport system during operations, the Failure Modes and Effects Analysis (FMEA) method is improved based on the α-cut fuzzy numbers, resulting in an α-cut based Fuzzy FMEA model ( α-FFMEA). The evaluation criteria of failure modes, including occurrence ( O), severity ( S), and detectability ( D), are described by using linguistic terms, effectively overcoming the limitations of traditional methods in dealing with uncertainty. Analytic Hierarchy Process (AHP) and entropy theory are used to assign the weights of O, S, and D reasonably and objectively, ensuring the scientificity and accuracy of the risk assessment. The α-cut fuzzy numbers and centroid method are then used to calculate the risk priority number of each failure mode across different α-cuts, providing a quantitative basis for system failure prevention and optimization. Finally, the transport system in the deep-sea linkage system is analyzed to validate the effectiveness and applicability of the model, offering important theoretical basis and practical guidance for the optimization and failure prevention of the deep-sea mining transport system.

Lightweight and integrated design are the key points in the design of the electromechanical equipment of the hovercraft. Through the analysis of the variable pitch hydraulic system of a ship, a comparative study of the conventional design scheme and the lightweight design scheme is conducted based on the design parameters of the variable pitch hydraulic integrated pump station that are obtained according to relevant design requirements. The results show that the lightweight and integrated design scheme can effectively reduce the overall weight of the pump station, and improve its integration. The trail production of the variable pitch hydraulic pump station has been conducted based on the lightweight design scheme. The main performance indicators of the hydraulic pump station can meet the system design requirements through the experimental research, which verifies the rationality of the proposed lightweight integrated hydraulic pump station design scheme. The lightweight design of the variable pitch hydraulic integrated pump station can provide reference for the subsequent hovercraft variable pitch pump station.

The environment of polar regions is very different from that of other ocean regions, including extremely cold (low temperature), icing, snowing, polar day and polar night, etc. The polar climate emulation laboratory will build an indoor polar environment for the design optimization and the test of polar equipment performance, ensuring the reliable operation of ships and offshore equipment under various polar environments. Currently, the military and civil institutions in some countries around the world have built climate laboratories for the operation simulation and experimental verification of the polar equipment and technology. The key technologies of polar climate emulation laboratory, such as the load calculation, air distribution design, and insulation system and refrigeration plant configuration, are summarized and discussed combined with the design cases of the ultra-low temperature container laboratory and the polar climate laboratory.

Lubricating oil and feed water are important items for the boiler inspection. However, the maintenance of the lubricating oil in the system is often neglected during when the ship is mooreding is often neglected in the ship during construction in shipyards, lacking while the concern of forthe water quality of the feed water quality is also lacking. It is therefore difficult to pass the inspection approval when facing the strict supervision of foreign ship owners. Based on the problems of the lubricating oil and feed water in the ship construction, the specific requirements of the relevant equipment manufacturers are studied to provide suggestions for the solutions of the relevant problems.

Three ways of application of shipborne automatic identification system (AIS) in ship navigation are systematically sorted out aiming at the safety hazard imposed due to the problem of the shipborne AIS only receiving messages but not sending out messages when it is in use. The timing of the information broadcast is given for the shipborne AIS in the severe weather conditions, narrow waterway and heavy traffic sea areas combined with the usage requirements. The reasonable and timely broadcasting of the AIS information of military ships can provide the effective means of the safety guarantee in the complex and changeable navigation environment.

Many shipowners choose to install the desulfurization system on ships as the approach of the entry into force of MARPOL Convention that sets limits on SO _X emissions from the ship exhausts in the global maritime space. Based on the project of a large crude oil tanker with the retrofitted desulfurization system, the power system after the transformation has been analyzed and studied. This project decide to add a desulfurization generator and a switchboard for the desulfurization system, in order to meet the requirements of the shipowner for the fuel economy of the ships during navigation. It can be seen that this scheme is not only feasible, but also can maximize the integrity of the original power system through the load estimation, short-circuit current calculation and alternative analysis of the power system.