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Facile Synthesis of Zn1-xCuxO Nanorods with a Very Broad Visible Band
Jianguo Lv,Changlong Liu,Wanbing Gong,Zhenfa Zi,Xiaoshuang Chen,Kai Huang,Feng Liu,Tao Wang,Gang He,Xueping Song,Zhaoqi Sun 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.5
Zn1-xCuxO nanorods with different Cu concentrations are prepared by a hydrothermal method. Bent and aggregated nanorods are obtained, which is attributed to centripetal surface tension of the evaporation and coagulation processes of the water film on the ZnO nanorods. The broad visible band consists of one violet, three blue,and one green emission. The violet emission is due to the transition of electrons from zinc interstitial (Zni)levels to the valance band. The three blue emissions may be attributed to the transition from extended Zni levels, which are slightly below the simple Zni level, to the valance band. The change of the green emission may be the result of competition between oxygen vacancies (VO) and zinc vacancies (VZn).
Research on stiffness control of a redundant cable-driven parallel mechanism
Jinshan Yu,Jianguo Tao,Guoxing Wang,Xiao Li,Haowei Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11
Controlling the stiffness of cable-driven parallel mechanisms (CDPM) is of great significance for improving performance in different tasks. A method for stiffness control of a redundant CDPM is presented in this paper. The stiffness matrix of the redundant CDPM is established. On this basis, considering the effect of coupling stiffness, a complete analytical formula for stiffness in different directions is established. Then, the influence of the vector λ on the stiffness of the CDPM in different directions is analyzed, and a method to control the stiffness of the CDPM through adjusting the vector λ is proposed. To avoid traversing the value of λ in the polygon formed by the set of λ to obtain the appropriate cable tension and keep the cable tension away from the upper and lower limit values, a change path of the vector λ is designed. When the vector λ changes along the path, the stiffness of the mechanism can be changed from the minimum value to the maximum value. This method has high computational efficiency and safety. Finally, the correctness and effectiveness of the stiffness control method are verified by experiments. The stiffness control method proposed in this paper can be used to control the stiffness in different directions, and can also be used for different types of redundant CDPMs.