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ObjectivesTo realize the online identification of hydrogen evolution characteristics and the quantitative design of the hydrogen control system for the lead-acid battery rooms of ships, a hydrogen concentration identification method based on the lumped model is proposed which comprehensively considers key parameters such as the hydrogen evolution rate of the battery and the ventilation & purification air volume and leakage air volume of the battery room.MethodsAccording to the environmental characteristics of the battery room, a mathematical model of the hydrogen concentration characteristics and hydrogen evolution rate prediction of the battery is established, and a corresponding calculation program is developed to analyze the hydrogen concentration variation characteristics of the battery room under different hydrogen evolution rates and ventilation & purification air volumes.ResultsThe various characteristics of the hydrogen concentration in the battery room are affected by the hydrogen evolution rate of the battery and the ventilation & purification air volume and leakage air volume of the battery room. When the hydrogen evolution rate is low (such as with a new battery), the leakage air volume will significantly affect the concentration rise rate. The daily operation frequency of the hydrogen purification system can reflect the actual hydrogen evolution rate of the battery and guide battery life evaluation.ConclusionsThe hydrogen evolution rate of the battery is correlated with several parameters. The proposed prediction model can accurately predict the hydrogen evolution rate of the battery and guide system design and operation strategy optimization. The related ideas and methods can also be extended to other cabin components similar to the hydrogen control system.

For obtaining environment-friendly and efficient green corrosion inhibitors， the photinia leaf extracts (PTF) were prepared by distilled water reflux method.The corrosion inhibition performance of PTF on Q235 steel in 1 mol/L hydrochloric acid was studied using electrochemical tests， weight loss tests， scanning electron microscopy and other methods.Results showed that as a mixed corrosion inhibitor， PTF could effectively inhibit the corrosion of Q235 steel in hydrochloric acid medium.The corrosion inhibition efficiency increased with the increase of PTF concentration and decreased with the increase of solution temperature.Furthermore， the inhibition efficiency of 4 g/L PTF was 87.99%at 293 K.The results of adsorption isotherm model showed that PTF could spontaneously adsorb on the surface of Q235 steel through physical effects， which conformed to the Langmuir single-layer adsorption model.

Wave impact is a strongly nonlinear interaction between waves and structures, and its load usually has the characteristics of a large peak value and short duration. In recent years, the extreme environment has frequently led to severe wave impacts on marine structures, resulting in loss of life and property, thus making the issue of wave impact become a great concern. For the complicated impact process, the theoretical analysis and model experiments can only provide simplified analytical solution and limited information on the slamming flow field. Therefore, numerical simulation has gradually become an effective means to study the issue of wave impact. Scholars at home and abroad have conducted a large number of numerical investigations on the load characteristics of wave impact, impact process, and its influencing factors on marine structures, gaining numerous important research conclusions. In this paper, the current progress, existing methods, and important conclusions of the numerical study of wave impact on marine structures are reviewed, which can provide useful references for further research on the numerical simulation of wave impact.