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Chongqing Wang,Pau Loke Show,Xiuxiu Zhang,Yijun Cao,Yasser Vasseghian 한국탄소학회 2023 Carbon Letters Vol.33 No.7
Organic wastewater causes serious environmental pollution, and catalytic oxidation is promising technique for wastewater treatment. Developing green and effective catalysts is currently challenging. In this work, green synthesis of nano zerovalent iron loaded onto porous biochar derived from popcorn is conducted, and catalytic oxidation of Rhodamine B (RhB) is evaluated in the presence of H2O2. Effect of process factors is examined on catalytic performance for RhB removal. The mechanism of RhB removal is discussed by characterizations (Fourier transform infrared spectra and Raman) and UV–vis spectra. RhB removal is improved with high catalyst dosage, low initial RhB concentration, and high reaction temperature, while it is slightly influenced by carbonization temperature of biochar, H2O2 dosage and pH value. Under conditions of BC-250 1.0 g/L, H2O2 0.01 mol/L, pH 6.1, and temperature 30 °C, the removal rate of RhB is 92.27% at 50 min. Pseudo first-order kinetics is used to fitting experimental data, and the activation energy for RhB removal in BC-250/H2O2 system is 39 kJ/mol. RhB removal in BC-250/H2O2 system can be attributed to adsorption effect and catalytic oxidation with the dominant role of hydroxyl radical. This work gives insights into catalytic oxidation of organic wastewater using green catalyst.
Chongqing Di,Xiaodong Yan,Xuming Lv,Chao Yan,Wei Ye,Defu Li 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12
A (TaC/Ta2C) carbide bilayer is obtained by vacuum carburizing technology on the surface of Ta substrate at 1673 K for 4,8, and 12 h. XRD, SEM and EBSD are utilized to investigated phase composition and the microstructure. The mechanicalproperties of the Ta and tantalum carburized materials are studied with Vicker’s hardness tester and nanoindenter, adhesionautomatic scratch tester, reciprocating friction and wear testing machine. The results show that the outside surface phasecomposition of the carbide bilayer is all the TaC phase. With the increase of the carburizing time from 4 to 12 h, the averagegrain size from approximately 500 nm to 10 μm, the thickness of the carbide bilayer is from 11 to 20 μm. The microhardnessincreases from 104.1 to 322.5 HV, and the elastic modulus are from 466.6 to 615.3 GPa. Adhesive strength is best at 8 h,49.1 N, compared to 19 N at 4 h and 36.5 N at 12 h. The friction and wear coefficient of Ta fluctuates significantly between0.6 and 1.0, after carburizing treatment, the friction and wear coefficient fluctuates smoothly, and the wear resistance is wellimproved.
On some open problems of Mahmoudi and Renshaw
Husheng Qiao,Chongqing Wei 대한수학회 2014 대한수학회보 Vol.51 No.4
This paper continues the investigation of covers of cyclic acts over monoids. Special attention is paid to (P)-covers and strongly flat covers of cyclic acts. In 2008 Mahmoudi and Renshaw posed some open problems and we gave some examples on them in 2012. In this paper, we obtained some further results on these problems and hence gave some deeper answers to them.
Xueguang Li,Chongqing Li,Penghui Li,Huizhong Hu,Xiansheng Sui 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.2
The crossbeam plays a vital role in computer numerical controlled milling machines, especially in machines with a gantry structure, as it directly influences the machining precision. In this study, a machine tool crossbeam was designed, and the modal frequency of the crossbeam was analyzed using the finite element model (FEM) analysis. In the improved structure obtained through FEM analysis, the X-type structure of the internal unit of the crossbeam was replaced by an O-type structure. The specific structure dimensions were further optimized using a neural-network algorithm and a nondominated sorting genetic algorithm. Finally, we calculated the effect of each crossbeam dimension on the mass, deformation, and frequency in a sensitivity analysis. After optimizing the crossbeam dimensions with respect to deformation, modal frequency, and mass, the structural characteristics of the original and optimized crossbeams were compared. After optimization, the mass and deformation were reduced by 7.45% and 3.08%, respectively, and the modal frequency was increased by 0.42%. These results confirm that the optimization improved the performance of the crossbeam structure.
Modelling and Simulating the Spatio-Temporal Correlations of Clustered Wind Power Using Copula
Ning Zhang,Chongqing Kang,Qianyao Xu,Changming Jiang,Zhixu Chen,Jun Liu 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.6
Modelling and simulating the wind power intermittent behaviour are the basis of the planning and scheduling studies concerning wind power integration. The wind power outputs are evidently correlated in space and time and bring challenges in characterizing their behaviour. This paper provides a methodology to model and simulate the clustered wind power considering its spatiotemporal correlations using the theory of copula. The sampling approach captures the complex spatiotemporal connections among the wind farms by employing a conditional density function calculated using multidimensional copula function. The empirical study of real wind power measurement shows how the wind power outputs are correlated and how these correlations affect the overall uncertainty of clustered wind power output. The case study validates the simulation technique by comparing the simulated results with the real measurements.
Modelling and Simulating the Spatio-Temporal Correlations of Clustered Wind Power Using Copula
Zhang, Ning,Kang, Chongqing,Xu, Qianyao,Jiang, Changming,Chen, Zhixu,Liu, Jun The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.6
Modelling and simulating the wind power intermittent behaviour are the basis of the planning and scheduling studies concerning wind power integration. The wind power outputs are evidently correlated in space and time and bring challenges in characterizing their behaviour. This paper provides a methodology to model and simulate the clustered wind power considering its spatio-temporal correlations using the theory of copula. The sampling approach captures the complex spatio-temporal connections among the wind farms by employing a conditional density function calculated using multidimensional copula function. The empirical study of real wind power measurement shows how the wind power outputs are correlated and how these correlations affect the overall uncertainty of clustered wind power output. The case study validates the simulation technique by comparing the simulated results with the real measurements.
ON SOME OPEN PROBLEMS OF MAHMOUDI AND RENSHAW
Qiao, Husheng,Wei, Chongqing Korean Mathematical Society 2014 대한수학회보 Vol.51 No.4
This paper continues the investigation of covers of cyclic acts over monoids. Special attention is paid to (P)-covers and strongly flat covers of cyclic acts. In 2008 Mahmoudi and Renshaw posed some open problems and we gave some examples on them in 2012. In this paper, we obtained some further results on these problems and hence gave some deeper answers to them.
Ordinal Optimization Theory Based Planning for Clustered Wind Farms Considering the Capacity Credit
Yi Wang,Ning Zhang,Chongqing Kang,Qianyao Xu,Hui Li,Jinyu Xiao,Zhidong Wang,Rui Shi,Shuai Wang 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.5
Wind power planning aims to locate and size wind farms optimally. Traditionally, wind power planners tend to choose the wind farms with the richest wind resources to maximize the energy benefit. However, the capacity benefit of wind power should also be considered in large-scale clustered wind farm planning because the correlation among the wind farms exerts an obvious influence on the capacity benefit brought about by the combined wind power. This paper proposes a planning model considering both the energy and the capacity benefit of the wind farms. The capacity benefit is evaluated by the wind power capacity credit. The Ordinal Optimization (OO) Theory, capable of handling problems with non-analytical forms, is applied to address the model. To verify the feasibility and advantages of the model, the proposed model is compared with a widely used genetic algorithm (GA) via a modified IEEE RTS-79 system and the real world case of Ningxia, China. The results show that the diversity of the wind farm enhances the capacity credit of wind power.