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The content of hydrogen is a key quantity in condition assessment and fault diagnosis of power transformer. Based on the density functional theory (DFT), the adsorption mechanism of Cu-doped SnO2 surface toward H2 has been systematically studied in this work. Firstly, the relaxation, the bond length, and overlap population of both the pure and Cu-doped SnO2 are computed. To determine the optimal doping position, the formation energies of four potential sites (i.e., Sn5c, Sn6c, Sn5c-s, and Sn6c-s) are then compared with each other. The adsorption energy and the electronic structure of SnO2 surface are analysed and discussed in detail. Furthermore, to estimate the partial atomic charges and the electrical conductance, the Mulliken population analysis is also performed. It has been found that the bridge oxygen is the most favourable position. The partial density of states of H2 after adsorption is broadened and shifted close to the Fermi level. A large amount of charges would be transferred and then released back into its conduction band, leading to the reduction of resistance and the enhancement of sensitivity toward H2. The results of this work provide references for SnO2-based sensor design.

A compact and wideband ultra‐high‐frequency antenna is developed in this work. Based on the Minkowski fractal geometry of the lateral boundaries of monopole and the upper boundary of ground plane, miniaturization is realized. Meanwhile, by optimizing the dimension of the semi‐elliptical part of monopole and the triangular notch of ground plane, the impedance bandwidth is enhanced. To confirm the performance of antenna, a series of experiments are conducted. The size and ratio bandwidth of antenna are compared with existing broadband ones. The proposed antenna with size of 0.3 λL × 0.25 λL covers the frequency ranging from 700 MHz to more than 3 GHz and possesses an average gain of 4.08 dBi.

C5F10O has been widely studied as a great potential alternative gas to SF6, a most potent industrial greenhouse gas that is predominantly used as an insulating medium in electrical equipment, due to its excellent insulation properties and environmental characteristics. Several experimental and theoretical attempts have been made and have obtained valuable results in the last five years. However, few researchers have thoroughly investigated the decomposition mechanism and the main decomposition pathways of the C5F10O/H2O system, which are important for evaluating the insulating and environmental performance and providing guidance for engineering application. Herein, the decomposition characteristics and mechanism of C5F10O in the presence of moisture content was studied by density functional theory calculations. The main types of decomposition products with relatively high content have been summarized based on the evaluation of cleavage reactions and the influence of moisture. The electrical, environmental and safety performances of the primary products were analyzed. CF3CFCF3, CF3CO, CF3, OH and H radicals are the most primary particles formed by dissociation of C5F10O and H2O. These particles may further convert into more than 20 kinds of relatively stable products, among which C4F10, C3F8, C6F14, C3HF7, C2F6 and CO are primary ones. In addition, COF2, CO2, CO and C3F6 can be used as components for estimating the degree of failures. The existence of H2O has a negative impact on the insulation and environmental performance. In particular, trace water has a direct contribution to the production of highly toxic COF2, CO and HF. Thus, it is necessary to strictly control the moisture and develop application standards before any industrial application of C5F10O in electrical equipment.