In the context of the increasingly strict pollutant emission regulations and carbon emission reduction targets proposed by the International Maritime Organization, the shipping industry is seeking new types of marine power plants with the advantages of high efficiency and low emissions. Among the possible alternatives, the fuel cell is considered to be the most practical technology, as it provides an efficient means to generate electricity with low pollutant emissions and carbon emissions. Very few comprehensive reviews focus on the maritime applications of the fuel cell. Thus, news reports and literature on the maritime applications of the fuel cell in the past sixty years were collected, and the industrial development status and prospects of the marine fuel cell were summarized as follows. Some countries in Europe, North America and Asia have invested heavily in researching and developing the marine fuel cell, and a series of research projects have achieved concrete results, such as the industrialized marine fuel cell system or practical demonstration applications. At present, the worldwide research of the marine fuel cell focuses more on the proton exchange membrane fuel cell (PEMFC). However, the power demand of the marine fuel cell in the future will show steady growth, and thus the solid oxide fuel cell (SOFC), with the advantages of higher power and fuel diversity, will be the mainstream in the next research stage. Although some challenges exist, the SOFC can certainly lead the upgrading and updating of the marine power system with the cooperative efforts of the whole world.

The skin friction consumes some of the energy when a train is running, and the coherent structure plays an important role in the skin friction. In this paper, we focus on the coherent structure generated near the vent of a train. The intention is to investigate the effect of the vent on the generation of coherent structures. The ventilation system of a high-speed train is reasonably simplified as a T-junction duct with vertical blades. The velocity signal of the cross duct was measured in three different sections (upstream, mid-center and downstream), and then the coherent structure of the denoised signals was analyzed by continuous wavelet transform (CWT). The analysis indicates that the coherent structure frequencies become abundant and the energy peak decreases with the increase of the velocity ratio. As a result, we conclude that a higher velocity ratio is preferable to reduce the skin friction of the train. Besides, with the increase of velocity ratio, the dimensionless frequency St of the high-energy coherent structure does not change obviously and St = 3.09 × 10⁻⁴–4.51 × 10⁻⁴.