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Graphite nitrogen, pyridine nitrogen and pyrrole nitrogen are the main nitrogen types in nitrogen-doped graphene materials. In order to investigate the mechanism of the oxygen reduction activity of nitrogen-doped graphene, several models of nitrogen-doped graphene with different nitrogen contents and different nitrogen types are developed. The nitrogen content is varied from 1.3 at% to 7.8 at%, and the adsorption energy is calculated according to the established models, then the band gaps are analyzed through the optimization results, so as to compare the magnitude of the conductivity. Finally, the oxygen reduction activity of graphite nitrogen-doped graphene (GNG) is found to be better than pyridine nitrogen-doped graphene (PDNG) and pyrrole nitrogen-doped graphene (PLNG) when the nitrogen content is lower than 2.6 at%, and the oxygen reduction activity of PDNG is the best when the nitrogen content was higher than 2.6 at%.

Temperature control is very important to keep the efficiency of solar cells, because the open-circuit voltage of the system is obviously dropped, when the temperature is raised, so as to a decline in output power of solar cells. Especially in the concentrated system, solar cells worked several times even hundreds of times in the irradiation conditions, so the temperature will significantly increased. This not only reduces the efficiency of power generation, but also impacts the life-span of the photovoltaic cells. In this paper, we analyze different ways of using system's thermal energy, and introduce the major methods and work features for concentrated solar cells cooling system, research progress about concentrated PV system in the domestic and abroad are summarized, in order to provide the foundation of improving the efficiency of the concentrated photovoltaic systems.

The left electrostatic precipitator of Shanghai Wujing Cogeneration Power plant No.7 boiler had quite low dust removal efficiency in the past more than ten years. Through analysis of the historical data and inspection on the spot, the nonuniform gas flow distribution of the inlet was thought as one of the key factors resulting in the low dust removal efficiency of the electrostatic precipitator. Then according to the proportion of 10:1, the organic transparent glass model of the electrostatic precipitator of Shanghai Wujing Cogeneration Power Plant was set up. Under the self-similarity principle, the velocity profile in the electrostatic precipitator was modeled for four conditions, none of the distributor, one distributor, two distributors and three distributors were installed in the flue pipe upstream of the electrostatic precipitator. The experimental data has been measured under four conditions laboratory bench respectively. With colorful gas injection, Air-flow was visualized. And then the optimized scheme for retrofit was determined. After retrofit installation, the field test was conducted. The result showed removal efficiency of electrostatic precipitator of Shanghai Wujing Power Plant was improved significantly.