To solve the problem of distribution network fault line selection caused by too few frequency components and no high amplitude low frequency components in the characteristic frequency band of transient zero sequence current, an improved ensemble empirical mode decomposition (MEEMD) method is proposed. Firstly, the influence of distributed generation on line zero sequence current was considered; then, the zero sequence current after fault was decomposed into multiple frequency signals according to frequency by meemd, and the eigenmode function was obtained and the highest frequency component is extracted; finally, the line selection result was obtained by analyzing the signal waveform of the highest frequency. The basic signal was not needed in this process, so the characteristics of the obtained signal were closer to the original signal. The process of fault line selection based on meemd was described in detail, and the influence of multi scene distribution network considering distributed generation on fault line selection is discussed. The simulation results show that the method can effectively improve the accuracy of fault line selection.

The damping vibration performance of the blade after metallization of steam turbine blades is studied. The turbine impeller was simplified and then modeled by ug software, and the modal analysis is carried out on the integral blade disk of the same thickness of the aluminum, titanium, aluminum titanium film blade and the uncoated blade by ANSYS software. The vibration pattern and natural vibration frequency are obtained, and the vulnerable parts of the impeller are observed as a whole；Harmonic response analysis of a single blade,The deformation of the four blades under the same load was further analyzed, and their damping effects were discussed.Combined with the experimental results, the test specimens were subjected to aluminum plating, titanium plating, aluminum plating first and then titanium plating treatment, and uncoated specimens formed a control group.Testing the damping performance of coatings with a Dynamic Mechanical Thermal Analyzer (DMA).The results show that the deformation of each step mode of the blade after coating is smaller than that of the blade without coating，it can play a certain damping effect on the blade coating.

The research and development of carbon-based non noble metal catalysts is one of the leading directions in the field of materials science and catalysis. Although, compared with conventional noble metal catalysts, it has the unique advantages of large surface area, wide source, low cost, environmental friendliness, corrosion resistance and so on. Combining the research progress of carbon-based non noble metal catalysts at home and abroad in recent years, the synthesis methods and research status of graphenebased non-metal catalysts, graphene-based non-precious metal oxide catalysts and carbon materials dispersed nonprecious metal catalysts are reviewed.

The center angle of 90° as a simulation model of the elbow，under the pressure of 0.15 MPa, the gas mass flow rate of 0.912 6 g/s condition, it selects four different liquid flow:0.27, 0.40, 0.53, 0.80 kg/s, and each condition is simulated using the FLUENT software. By numerical simulation results, it analyzes the fluid flow characteristics at the elbow at each of the conditions, and get the basic law and characteristics of elbow slug flow under different liquid flow.

By analyzing the failure of ERPN32200 pump mechanical seal, it was found that the actual sealing effect of mechanical seals is related not only to the performance itself, but also to the precision, size, and assembly quality of the relevant parts. In the meantime, it was proposed that the corresponding measures to cope with the problems, thus prolonging the service life of mechanical seals.