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Effect of silicon carbide on carbonization and morphology behavior of coal tar pitch
Wenjuan Zhang,Shihua Song,Xianren Zeng,Genhui Teng,Qi Wang 한양대학교 세라믹연구소 2017 Journal of Ceramic Processing Research Vol.18 No.10
Coal tar pitch (CTP) is a quite promising candidate for the production of carbon materials. However, the application of CTP is restricted by its poor properties at elevated temperature. In this paper, silicon carbide was used to modify CTP and thecarbonization and morphology behavior of CTP and the CTP modified with silicon carbide were studied by thermogravimetry and differential scanning calorimetry (TG-DSC), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show silicon carbide and CTP can coalesce well when the ratio of silicon carbide to CTP is 12% and the carbonization yield of CTP at 900 o C increases from 35.86% to 40.56% after the modification of CTP. Further, the addition of silicon carbide to CTP can reduce the temperature at which the reaction of thermal polymerization happen during the carbonization process of CTP and can facilitate the carbonization of CTP. In addition, little pore distributes on the surface of the heat-treatment products after the modification of CTP with silicon carbide.
Preparation of Functionalized Magnetic Silica Nanospheres for the Cellulase Immobilization
Wenjuan Zhang,Jianhui Qiu,Limin Zang,Eiichi Sakai,Huixia Feng 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.1
Cellulase was immobilized on functionalized magnetic silica nanospheres using glutaraldehyde as a cross-linking agent. The morphologies, structures and magnetic properties of this immobilized cellulase were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential thermal analysis and vibrating sample magnetometry. The properties of immobilized cellulase were investigated, including the amount of immobilized cellulase and its relative activity, stability and reusability. The results indicated that immobilized cellulase exhibited better resistance to high temperature and pH inactivation in comparison to free cellulase. Moreover, immobilized cellulase with and without cross-linking agent were investigated and the former had greater amount of immobilized cellulase and better operational stability. The amount of immobilized cellulase with the cross-linking agent was 92 mg/g support. Furthermore, the activity of the immobilized cellulase was still 85.5% of the initial activity after 10 continuous uses, demonstrating the potential of this immobilized cellulase for large-scale biofuel production.
Wenjuan Zhang,Haomiao Ma,Junli Zhang,Lingling Chen,Yang Qu 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4
This study investigates the multi-objective fuzzy optimization of crowbar resistance for the doubly fed induction generator (DFIG) low-voltage ride-through (LVRT). By integrating the crowbar resistance of the crowbar circuit as a decision variable, a multi-objective model for crowbar resistance value optimization has been established to minimize rotor overcurrent and to simultaneously reduce the DFIG reactive power absorbed from the grid during the process of LVRT. A multi-objective genetic algorithm (MOGA) is applied to solve this optimization problem. In the proposed GA, the value of the crowbar resistance is represented by floating-point numbers in the GA population. The MOGA emphasizes the non-dominated solutions and simultaneously maintains diversity in the non-dominated solutions. A fuzzy-set-theory-based is employed to obtain the best solution. The proposed approach has been evaluated on a 3 MW DFIG LVRT. Simulation results show the effectiveness of the proposed approach for solving the crowbar resistance multi-objective optimization problem in the DFIG LVRT.
Zhang, Wenjuan,Ma, Haomiao,Zhang, Junli,Chen, Lingling,Qu, Yang The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4
This study investigates the multi-objective fuzzy optimization of crowbar resistance for the doubly fed induction generator (DFIG) low-voltage ride-through (LVRT). By integrating the crowbar resistance of the crowbar circuit as a decision variable, a multi-objective model for crowbar resistance value optimization has been established to minimize rotor overcurrent and to simultaneously reduce the DFIG reactive power absorbed from the grid during the process of LVRT. A multi-objective genetic algorithm (MOGA) is applied to solve this optimization problem. In the proposed GA, the value of the crowbar resistance is represented by floating-point numbers in the GA population. The MOGA emphasizes the non-dominated solutions and simultaneously maintains diversity in the non-dominated solutions. A fuzzy-set-theory-based is employed to obtain the best solution. The proposed approach has been evaluated on a 3 MW DFIG LVRT. Simulation results show the effectiveness of the proposed approach for solving the crowbar resistance multi-objective optimization problem in the DFIG LVRT.
The Efect of ADRC on Vehicle Braking Performance
Wenjuan Li,Qi Zhang,Yuan Zhang 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.2
The active disturbance rejection control (ADRC) was proposed as a control strategy for anti-lock braking system (ABS) to improve the braking performance. A real-time simulation model was developed after analyzing the brake force during vehicle braking and the ADRC principle. This experimental real-time simulation platform was developed based on xPC Target. This ABS study was conducted on a dry concrete pavement, and the braking performance indices were analyzed under the ADRC and the bang–bang control. The results suggest that the braking performance is more superior with ADRC than the bang–bang control because the braking time and braking distance were reduced. The xPC Target is a less-costly and practical method for real-time simulation.
WenJuan Yan,YingYing Cai,Qun Zhang,YuSi Liu,WenChun Xu,YiBing Yin,YuJuan He,Hong Wang,XueMei Zhang 한국미생물학회 2013 The journal of microbiology Vol.51 No.4
Hsp100/Clp proteins have crucial functions in the protein quality control, stress tolerance, and virulence of many pathogenic bacteria. ClpE is an important virulence factor involved in adherence and invasion in Streptococcus pneumoniae. To explore the underlying mechanism, we screened ClpE interaction proteins using a bacterial two-hybrid system and co-immunoprecipitation. We used ClpE as bait and constructed the pBT-ClpE bait plasmid for two-hybrid screening. Then, we constructed ClpE::GFP fusion for co-immunoprecipitation screening using anti-GFP monoclonal antibody. We obtained eight potential ClpE interaction proteins,including carbamoyl-phosphate synthase, pyruvate oxidase (SpxB), phosphoenolpyruvate-protein phosphotransferase,aminopeptidase N (pepN), L-lactate dehydrogenase, ribosomal protein S4, sensor histidine kinase (SPD_2019), and FtsW (a cell division protein). FtsW, SpxB, pepN, and SPD_2019 were confirmed to interact with ClpE using Bacterial Two-hybrid or Co-immunoprecipitation. Morphologic observations found that ΔclpE strain existed in abnormal division. β-Galactosidase activity assay suggested that ClpE contributed to the degradation of FtsW. Furthermore, FtsW could be induced by heat shock. The results suggested that ClpE might affect cell division by regulating the level of FtsW. These data may provide new insights in studying the role of ClpE in S. pneumoniae.