The calculation method of direct-current (DC) short-circuit current and analysis of selective protection of fuses are important aspects of the design of the DC integrated power system. The design directly affects the selective protection scheme of fuses in the DC distribution system and the operational stability of the DC distribution system. The calculation principle and method of the single module short-circuit current in marine DC distribution system are presented for equivalent calculation of the ship’s DC distribution system. By selecting different short-circuit points, the impact of different short-circuit points on the DC comprehensive power system during short circuit. The short-circuit currents of different branches are calculated to determine the fuse specification through the actual I2T curve of the branch. The error between the simulation results obtained from the equivalent model simulation and the practical calculation is within 1% by analyzing the practical examples. By using the MATLAB/SIMULINK equivalent model simulation method, the calculation of the short-circuit current of the DC distribution system and the reasonable selection of the fuse can be conducted without establishing a detailed SIMULINK model and performing tedious formula calculations.

The interaction between ship sails and the air flow field is a typical fluid-structure interaction problem, which has attracted great attention in recent years. Research on the mechanical behavior of the fluid-structure interaction for ship sails is of great significance to the structural optimization design of the sails and the improvement of the ship dynamic performance. In order to fully understand the state-of-the-art of the fluid-structure interaction of ship sails, the current relevant literatures have been reviewed from the aspects of numerical simulation and experimental research. The adopted numerical methods are summarized from three aspects of air flow field, sail structure, and fluid-structure interaction. The current experimental methods are classified and analyzed from the viewpoints of the full-scale and model-scale tests. The future research direction of the fluid-structure interaction of ship sails is analyzed and discussed by comparing the advantages and disadvantages of different methods.

The strength and fatigue life of the bolted base of the marine diesel generator sets are analyzed to ensure its long-term operation reliability. The static strength of the bolted base is calculated based on the finite element modeling of the bolted base. The strength of the base bolts are calculated based on the VDI 2230 standard. The response vibration characteristics of the bolted case under the operating conditions are calculated to analyze its fatigue life according to the base load in the actual vibration test and the rated load. The results show that the static strength of the bolted base calculated by the finite element method meets the requirements, and the bolt strength calculated by the VDI 2230 standard also meets the requirements. The response calculations based on the two methods show that the bolted base will not experience fatigue failure during the 20-year safe operation period.