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- 저자 : Hongcheng Li (검색결과 4 건)
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Hongcheng Li,Kongzhai Li,Xing Zhu,Yunpeng Du,Yonggang Wei,Kang Zhai,Hua Wang 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-
The fabrication of mesoporous PrxZr1xO2d solid solutions with different Pr/Zr molar ratios is reported in the present work. Based on a systematic investigation, the anion of Zr precursor and template species are found to play the most important roles for the formation of mesoporous structure. The triblock copolymer Pluronic F127 template helps to generate porosity in the matrix by self-assembly into micelle, while the additional Cl1 from Zr precursor can lead to the enhancement of the interaction between non-ionic micelles. The physicochemical properties of the obtained samples were studied by means of N2 sorption analysis, TEM, XRD, H2-TPR, O2-TPD and XPS technique. It is found that, compared with the nonmesoporous counterparts, the mesoporous PrxZr1xO2d solid solutions possess much higher specific surface area (139 m2 g1) and enhanced redox ability. Also, the ability to release oxygen is improved after aging at high temperature. For the catalytic soot oxidation, the fresh mesoporous Pr0.1Zr0.9O2d catalyst (calcinated at 500 C) shows high activity in a loose contact condition (T50 = 399 C). It should be highlighted that the T50 values over the three mesoporous PrxZr1xO2d samples decrease by 8–24 C after aging at 800 C for 3 h. This suggests that the mesoporous PrxZr1xO2d solid solution is an ideal candidate for catalytic application at high temperatures.
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Energy Dissipation Characteristics Modelling for Hot Extrusion Forming of Aluminum-Alloy Components
Hongcheng Li,Yuanjie Wu,Huajun Cao,Feng Lu,Congbo Li 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.6
The hot extrusion forming process is widely used to process aluminum-alloy components in both the automobile and aircraft manufacturing industries. Since it involves pushing the material through the die at increased temperature, it is very energy-intensive despite requiring less blank material allowance. During hot extrusion forming, the multi-stage dynamic conversion of electricity, mechanical energy, and hydraulic energy to heat results in high energy dissipation. In order to improve the power and energy conversion efficiency of hot extrusion forming process, it is necessary to identify the energy dissipation characteristics. The transfer and conversion paths of the electrical, mechanical, and hydraulic energy from the motor to the hydraulic cylinder were firstly depicted based on the motion cycle of the extruder. A bond graph-based energy dissipation model was then proposed for dynamically identifying the energy-saving potentials. The energy dissipation model integrated the power bond graph sub-model of energy conversion elements such as motor, pump, hydraulic valve group, and hydraulic cylinder. These power bond graph sub-models were separately developed to find the energy dissipation state equations of energy conversion elements. An experiment was carried out using data obtained from the energy management system to validate the bond graph-based energy dissipation model. The results have shown that the power and energy conversion efficiency of hot extrusion forming is primarily controlled by the parameters such as extrusion velocity and extrusion force. Both the higher extrusion velocity and lower extrusion force will reduce the power and energy conversion efficiency. An optimal combination of extrusion velocity and pressure can achieve the lowest energy consumption per unit product.
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Analysis of large concrete storage tank under seismic response
Jingyuan Li,Xiaochuan You,Hongcheng Cui,Qiang He,Jinsan Ju 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.1
This study adopted the finite element software ABAQUS to trace the dynamic response history of large reinforced concrete storagetank during different seismic excitations. The dynamic characteristics and failure modes of the tank’s structure were investigated by consideringthe rebar’s effect. Calculation results show that the large concrete storage tank remains in safe working conditions under a seismicacceleration of 55 cm/s2. The joint of the concrete wall and dome begins to crack when seismic acceleration reaches 250 cm/s2. Asthe earthquake continues, cracks spread until the top of the wall completely fails and stops working. The maximum displacement of theconcrete tank and seismic acceleration are in proportion. Peak displacement and stress of the tank always appear behind the maximumacceleration.
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Zhaoming Huang,Zijun Zheng,Tao Wang,Li Wang,Hongcheng Gan,Weiguo Chen 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.4
On a single-cylinder gasoline engine test bench, the experimental study of the effects of polishing the combustion chamber wall and piston top surface on the indicated thermal efficiency and combustion characteristics were carried out, and the mutual influence of combustion phase, combustion duration and indicated thermal efficiency before and after polishing the wall of combustion system was systematically analyzed. The results show that when the single-cylinder gasoline engine operates at stoichiometric air-fuel ratio, low load and low compression ratio, the heat transfer loss of the polished combustion chamber is reduced and the fuel economy is improved, and the indicated thermal efficiency is increased from 40.8 to 42.2 %. With the increasing of load and compression ratio, the knock effect caused by the reduction of heat transfer loss after polishing is enhanced, and the combustion phase is delayed and the combustion duration is prolonged, which eventually leads to the decrease of the indicated thermal efficiency. After combustion chamber polishing, HC and NOx decrease by up to 70 %. With the increase of compression ratio, HC emission gradually increases, while NOx emission gradually decreases. There is no obvious change trend of CO emission before and after polishing. When the gasoline engine operates in lean combustion mode, the indicated thermal efficiency increases effectively, and the highest thermal efficiency exceeds 45 %; When the gasoline engine operates at indicated mean effective pressure of 1.05 MPa, the reduction of heat transfer loss in the combustion chamber after polishing enhances the knocking tendency, resulting in the overall decrease of the gross indicated thermal efficiency compared with that before polishing.
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