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Haibing He,Xing Tang,Bo Shi,Cuifang Cai 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.11
The poorly water-soluble drug lovastatin (LVA) is an inhibitor of 3-hydroxy-3-methylglutarylcoenzyme A reductase and has a slow dissolution rate. In this study, a microcrystal dispersion (MCD) technique was used in the preparation of LVA to increase its dissolution rate and then combining with an extrusion-spheronization method, microcrystalline cellulose (MCC) matrix sustained-release pellets containing LVA-MCD were developed and characterized in vitro. Photomicrographs indicated that LVA-MCD existed as fine crystals, of which the mean particle size was reduced from 65.75 μm to 3.97 μm and the dried LVA-MCD powders released completely within 2 hours. SEM results during the release process showed that pellets possessed a matrix structure and after the dissolution test, this matrix structure became loose and porous. The release of LVA was fast and complete, and accumulated release by the optimal formulation was: 0.5 h (20.23 ± 3.40%), 2 h (56.87 ± 2.85%), 4 h (78.71 ± 3.42%), and 8 h (96.81 ± 3.30%). The 3 months accelerating test at 40^oC and 75% RH demonstrated that drug release of pellets was not changed and drug degradation was less than 1%. Thus, a novel MCD process with MCC matrix was feasible and effective to get complete release without a lag time for the poorly water soluble drug, LVA, with high stability.
Aiguo Tan,Zhihan Tang,Xianbo Sun,Jianwei Zhong,Honghua Liao,Haibing Fang 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4
In view of the problem that large-scale and high-penetration wind power access may weaken the stability of small interference in the power grid, this study proposes a novel additional damping controllers for the doubly-fed induction generator (DFIG) based on the genetic algorithm. A DFIG model and its control system is built, and the parameters of the controller are tuned using the genetic algorithm to optimize the control efect. Based on Western System Coordinating Council (WSCC) 3-machine 9-node system, multi-scenario simulation results verifes that the additional damping controller proposed in this study performs better to suppress the low-frequency oscillation than the power system stabilizer (PSS) installed on the synchronous generators which are farther to the disturbance point. Meanwhile, the proposed strategy is compared with the reactive power modulation control, which can provide a reference for engineering applications of an added DFIG damping controller.
A Cut‑Out Strategy for Wind Turbines that Ensures Low‑Voltage Ride‑Through Capability
Aiguo Tan,Zhihan Tang,Xianbo Sun,Jianwei Zhong,Honghua Liao,Haibing Fang 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4
To ensure the dynamic stability of the system and improve low-voltage ride-through (LVRT) capability, this study presents a cut-out strategy for doubly-fed induction generator (DFIG) wind turbines that combines reactive power output with asynchronous load reduction. This strategy reduces the risk of the large-scale disconnection of DFIGs in a wind farm by regulating the reactive power output of DFIGs in the wind farm and removing DFIGs in an asynchronous state based on the reduction ratio. Simulation results demonstrate that the implementation of this strategy can help increase the voltage at the point of common coupling and the LVRT time for a wind farm.
Ke Wei,Qing Ma,Haibing Tang,Xiaoguang Fan,Jian Zhang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.12
The folding, die underfilling, rib shifting and average grain size of primary equiaxed were investigated using five different unequal thickness billets in transitional region of Ti-alloy multi-rib component under isothermal local loading and compared with integral loading. In terms of the macro deformation, the results show that the material transfers from the second-loading zone into the first-loading zone and the die underfilling decreases with the initial volume of the first-loading zone increasing, which reduces the risk of folding and rib shifting. However, that folding and rib shifting did not appear during the integral loading. Nevertheless, when the initial volume of the first-loading zone reaches a certain value, the die underfilling is aggravated both in local and integral loading. With respect to the microstructure, as the initial volume of the first-loading zone increases, the average grain size is decreased after the first-loading step, but increased after the second-loading step with consideration of one single loading step, which lead to the grain size being barely influenced by different billet volume distribution under both loading steps.