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To understand the space charge characteristics of ethylene propylene rubber (EPR) used in MV/HV power cables under thermal stress, the space charge profile is measured by the pulsed electro-acoustic method under 20 kV/mm at 120 and 160 °C. The complex permittivity and physicochemical properties at the different ageing stages are measured and analyzed for an understanding of the effects of thermal ageing on space charge characteristics. The trap properties of EPR during thermal ageing is calculated and analyzed based on the space charge decay model. The results show that both the ageing time and temperature can affect the space charge characteristics of EPR. The space charge characteristics of EPR can be ascribed to the trapping sites caused by the complex chemical and physical structures during thermal ageing. Under the thermal oxygen process, the polar groups and ions increase because of the EPR molecular chain breakages, and the charge injection from the electrodes increases. Based on the decay model of space charge and isothermal decay current theory, the distribution of trap levels in EPR at different ageing stages is obtained. The trap distribution under different ageing process can be explained by the theory of trap filling.

With the development of intelligent theory of computer vision and the popularization of surveillance cameras, intelligent video analysis and surveillance technology has been widely used. The traditional video monitoring system will produce a large amount of video information in the application process, which is not conducive to the storage and reference of information, and it can not carry out real-time warning, and has poor robustness to the bad environment. In view of these disadvantages, this paper proposes an improved video enhancement and concentration method, which has a good effect in ensuring the video concentration ratio and the target loss rate, and can improve the shortcomings brought by manual reference. Aiming at the problem of real-time early warning, an intelligent video analysis method is proposed to realize the functions of event alarm and detection analysis. It is of great significance to improve the video monitoring management level of the substation and realize the unattended operation of the substation.

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Here, we investigate structure and mechanical change of Cu and Al current collector during cycling and analyze the contribution to capacity attenuation of Sb-based lithium-ion batteries (LIBs). There exists migration of C, Sb, and Li atoms to the inside of Cu current collector, and diffusion of Li, Co, and O atoms to the inside of Al current collector during cycling, which results in the formation of a porous film of Li2SbCu (with the thickness of 21 µm after 100 cycles) and a relatively dense film of Al2O3 (with the thickness of 23 µm after 100 cycles) on the surface of Cu and Al current collector, respectively. The formation of films results in a weak bond between active layer and current collector, and the increase of hardness of 0.84 GPa and modulus of 22.5 GPa for Cu current collector after 100 cycles, which is adverse to the charge capacity and cycling stability. Nevertheless, Al2O3 films caused hardness decrease of 0.53 GPa and modulus decrease of 18.93 GPa of Al current collector after 100 cycles, which contributes to the improvement of cycling stability and charge capacity. This study provides an understanding of the capacity loss of Sb-based LIBs from the perspective of structural degradation of current collectors.