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Limits of phase locked loop (PLL) are necessary to make sure the transient converter frequency bounded in a safety range. This leads to the grid-connected voltage source converter (VSC) with limits of PLL as one switched system. Stability of switched dynamic system is fully discussed in this paper. One conservative analytical stable region of the unbounded autonomous system is derived by Lyapunov method. It is proved that when bounds are touched, any trajectory of the studied switched system deviates from these bounds at two fixed switching Points. Moreover, the switched system energy is non-increasing when trajectories lie inside the derived analytical stable region. Based on these properties of switched system, it is proved that to ensure the globally asymptotically stability, the fixed switching Points should be placed inside the derived stable region of the unbounded autonomous system. Finally, stabilization method is proposed via placement of the fixed switching Points so that the globally asymptotically stability is ensured.

Different types of carbon nanotubes as carriers were used to prepare ruthenium nano-catalysts loaded outside (named as Ru/CNTs) and inside (named as Ru@CNTs) the tube. The catalysts were modified in situ with chiral ligands (1S, 2S)-DPEN (1S, 2S)-DPEN = (1S, 2S)-1,2-diphenyl-1,2-ethanediamine). In the presence of TPP (TPP = triphenylphosphine) as the stabilization, the catalytic asymmetric hydrogenation of acetophenone was carried out with the modified catalysts. A novel approach to prepare the inside-loaded catalysts of Ru@CNTs was explored in the preparation. The catalyst can efficiently prevent the Ru nanoparticles from oxidizing in the air in this approach. The catalysts were well characterized by means of TEM, XRD, XPS, BET and H 2 Pulse Chemisorption. The effect of the diameter of carbon nanotubes on the particle size of ruthenium nanoparticles loaded on the tubes was also well studied. When Ru@CNTs (8 %, S) ("S" abbreviated from "short", the same below) was used in the asymmetric hydrogenation of acetophenone, 100 % conversion of acetophenone achieved, and the ee value reached 76.4 %. Under the same reaction conditions, 100 % conversion of acetophenone as well as the highest ee value of 80.8 % were obtained when Ru/CNTs (8 %, S) was applied in the reaction.

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Novel ZnIn2S4/FeUiO-66 (ZFeU) photocatalyst with different proportion of FeUiO-66 has been successfully prepared by a facile one-pot solvothermal reaction. The as-synthesized nanocomposites have been thoroughly characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), Brunauer–Emmett–Teller (BET) characterization, photoluminescence (PL) analysis and electrochemical impedance spectrum (EIS). The photocatalytic performance of ZFeU nanocomposites for the photodegradation of RhB under visible light irradiation was better than that of ZnIn2S4 and FeUiO-66 alone. The experiment results showed the 20% ZFeU nanocomposites had the best photocatalytic properties. At the same time, a probable mechanism was discussed and it was believed that introduction of FeUiO-66 on ZnIn2S4 would minimize the recombination of photogenerated electron-hole pairs, leading to the enhancement of the photocatalytic activity.