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Lihua Deng,Juntao Fei,Changchun Cai 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10
This paper presents a global fast terminal sliding mode (GFTSM) control based on backstepping design for active power filter(APF). Power system is a typical nonlinear system. Its mathematic model can be reduced order by backstepping method. Power system is decomposed into low-level subsystems until finalizing the design of the control law. The System’s stability is ensured by Lyapunov framework. The sliding mode control is added into backstepping control to expand the application scope of control. The sliding mode control doesn’t need accurate model of system. Therefore robustness of APF control is improved. Global fast terminal control is added into sliding mode control. The nonlinear term of GFTSM control makes the system converge quickly when far from equilibrium point, and the linear term do when near equilibrium point. It makes the system’s state tracking error reach zero in finite time. The control speed of system is enhanced. An experiment based on MATLAB/SIMULINK is designed to compare GFTSM backstepping control with pure backstepping control, and experimental results confirm the validity of proposed APF controller for a three-phase three-wire system.
A Theoretical Study on the Mechanism of Decarboxylations for Hydroxymandelate Synthase
Qing-An Qiao,Qiuxian Li,Changchun Liu,Xiao Sun,Honglan Cai,Lixiang Sun,Huayang Wang 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.6
Hydroxymandelate synthase is one type of alpha-keto acid-dependent oxygenases and plays an important role in the biosynthesis of hydroxyphenyl-pyruvate. The ferrous and ferryl intermediates in the reaction were considered to be very important in the DNA repair process. The mechanism of hydroxymandelate synthase was investigated by a theoretical method based on B3LYP/LACVP*. The data indicated that each decarboxylation went through a process of direct dioxygen insertion. The first oxidative decarboxylation experienced only one transition state, while there were two potential pathways for the second decarboxylation process. The calculation data showed that the stepwise one was favored to the concerted one due to the lower energy barrier. The process to form the iron-superoxide was the rate-limiting step. After two consecutive decarboxylations, a proton transfer reaction was needed to obtain the target products. Two possible transition states were found out to achieve this step. The one with a six-membered ring structure was preferred because of the lower activation energy. In addition, several ferryl species with high spins were captured in the whole process, which could be supplied as requisite substrates for DNA repair reaction.