Papers by Author: Zhi Yong Zhang

Abstract: In this paper, the photocatalytic properties of W-doped monoclinic BiVO₄ were studied by CASTEP of MS-5.5 software under PWPP based on density function theory (DFT). The results showed that the band gap narrowed and the absorption edge red shifted after 5d atomic orbit of W mixing into the valence band of BiVO₄ crystallites, which could effectively improve the photocatalytic activity of BiVO₄ crystallites. The calculated results also implied that the photocatalytic properties of monoclinic BiVO₄ crystallites could be improved by doping the transition metal with 5d⁴ orbital.

Abstract: A novel method in the solution of the pointing problem for electro-optical pointing system (EOPS) is presented in this paper. Firstly, the error sources are analyzed in detail. And then, a linear model whose parameters have definitely physical meaning is developed to improve pointing accuracy. Extensive experiments have been carried out and the results show that the system errors can be eliminated by the model effectively and the pointing accuracy of the azimuth and elevation axes have been improved from 0.4541º and 0.2959º to 0.038º and 0.031º respectively.

Abstract: Aluminum alloy has being widely used in modern automobile and aeronautic industry. However, the welding of aluminum alloy, especially high strength aluminum alloy，is difficult. Porosities are usually brought in the weld metal. In this paper, MIG welding using mixed gas shielding is carried out. The characteristic shapes of porosity in weld metal are described, the mechanism of porosity formation is analyzed, and the factors that influence the tendency of porosity formation are studied. Experiment results indicate that by the use of mixed shielding gas of 38%He+62%Ar, the number of porosity is reduced, the width of HAZ and softened zone is decreased, and the mechanical properties of welded joint is increased.