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Porous carbon microtubes were prepared by pyrolysing an inexpensive and abundant natural fungus at a high temperature, followed by activation and doping with nitrogen (N) and sulfur (S) elements at a lower temperature. The performance of the porous carbon as electrocatalysts for oxygen reduction reaction (ORR) was systematically investigated. The pristine carbon without doping shows a high electrocatalytic activity, which is strongly dependent on the degree of graphitization. By N- and S- dual-doping, the catalytic performance is further enhanced, exhibiting a four-electron oxygen reduction pathway, which is attributed to the redistribution of spin and charge densities. These results suggest that obtaining graphitic porous carbon from natural precursors combined with heteroatom-doping, provide an effective method of producing high performance carbon materials which might be suitable for various electrochemical energy applications.

The reliability of DC arresters is one of the basis of safe operation for HVDC transimission system, the aging test is the main measure to obtain the reliability of arresters, and therefore, is of great importance. The test voltage with ideal waveforms had not been produced before by any of the test equipment when it is loaded. The paper introduces a method to produce the aging test ripple voltage waveforms of 6 pulses and 12 pulses converter which fully considers the influence of trigger angle and commutation angle. The paper designed a kind of ripple voltage power source which can series, and produce the ripple waveform of any trigger angle and commutation angle, the output voltage of one module is up to 1kV. The device went through 1000 hours of testing, and commutation process can be seen in the oscillograph clearly, including stable commutation overshoot. The oscillograph also show that the fundamental frequency of the waveform is stable, and waveform distortion is small and can be ignored. The output voltage meets the requirements of aging test for various types of DC arresters.

In order to study fatigue performance of foamed lightweight soil and forecast its fatigue life in the supporting project, on the base of preliminary tests, beam fatigue tests on foamed lightweight soil is conducted by using UTM-100 test system. Based on Weibull distribution and lognormal distribution, using the mathematical statistics method, fatigue equations of foamed lightweight soil are obtained. At the same time, according to the traffic load on real road surface of the supporting project, fatigue life of formed lightweight soil is analyzed and compared with the cumulative equivalent axle loads during the design period of the pavement. The results show that even the fatigue life of foamed lightweight soil has discrete property, the linear relationship between logarithmic fatigue life and stress ratio still performs well. Especially, the fatigue life of Weibull distribution is more close to that derived from the lognormal distribution, in the instance of 50% guarantee ratio. In addition, the results demonstrated that foamed lightweight soil as subgrade filler has good anti-fatigue performance, which can be further adopted by other projects in the similar research domain.