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Secondary Science Teachers` Employment System in China Mainland
( Jingjing Luo ),( Xingkai Luo ) 한국과학교육학회 2008 한국과학교육학회 학술발표 및 세미나집 Vol.2008 No.1
This article presents how in China mainland a school and a school district find their science teachers. Based on studying relevant materials and years of intensive involvement in teacher education and recruitment practices the authors draw three features of the current secondary science teachers` employment system in China mainland: certification control conducted very loosely selection criteria and process vary with schools and school districts due to the remarkable difference existed among them the normal universities/colleges established originally only for secondary science teacher education still playa vital role in shaping effecting quality of teacher candidates although no one of them for a long time have focused on only doing what they were supposed to do. For further development, changes and essential reform are expected duo to the increasing promotion toward the internal quality of education and therefore high quality of teachers and teacher candidates.
Zhuang, Baotang,Li, Yong,Luo, Xianwu,Pan, Halin,Ji, Jingjing Korean Society for Fluid machinery 2014 International journal of fluid machinery and syste Vol.7 No.1
The propellant acquisition vane (PAV) is a key part of a vane type surface tension propellant management device (PMD), which can manage the propellant effectively. In the present paper, the fluid transportation behaviors for five PAVs with different sections were investigated by using microgravity drop tower test. Further, numerical simulation for the propellant flow in a PMD under microgravity condition was also carried out based on VOF model, and showed the similar flow pattern for PAVs to the experiment. It is noted that the section geometry of PAVs is one of the main factors affecting the fluid transportation behavior of PMD. PAVs with bottom length ratio of 5/6 and 1/2 have larger propellant transportation velocity. Based on the experiments, there were two stages during the process of propellant transportation under microgravity environment: liquid relocation and steady transportation stage. It is also recognized that there is a linear correlation between liquid transportation velocity and relative time's square root. Those results can not only provide a guideline for optimization of new vane type PMDs, but also are helpful for fluid control applications in space environment.
Baotang Zhuang,Yong Li,Xianwu Luo,Halin Pan,Jingjing Ji 한국유체기계학회 2014 International journal of fluid machinery and syste Vol.7 No.1
The propellant acquisition vane (PAV) is a key part of a vane type surface tension propellant management device (PMD), which can manage the propellant effectively. In the present paper, the fluid transportation behaviors for five PAVs with different sections were investigated by using microgravity drop tower test. Further, numerical simulation for the propellant flow in a PMD under microgravity condition was also carried out based on VOF model, and showed the similar flow pattern for PAVs to the experiment. It is noted that the section geometry of PAVs is one of the main factors affecting the fluid transportation behavior of PMD. PAVs with bottom length ratio of 5/6 and 1/2 have larger propellant transportation velocity. Based on the experiments, there were two stages during the process of propellant transportation under microgravity environment: liquid relocation and steady transportation stage. It is also recognized that there is a linear correlation between liquid transportation velocity and relative time's square root. Those results can not only provide a guideline for optimization of new vane type PMDs, but also are helpful for fluid control applications in space environment.
Synthesis and properties of ultrafine YAG powder via low-temperature microwave hydrothermal method
Yue Liu,Jieguang Song,Lin Chen,Huihui Luo,Guojian Lin,Peng Chen,Chenhui Wei,Jingjing Liu 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.4
Yttrium aluminum garnet (YAG) has good optical properties and has been widely used in engineering. The preparation ofconventional YAG powder is costly due to its high synthesis temperature, so lowering the synthesis temperature is the mosteffective way to save cost. The ultrafine oxide composite powder was rapidly synthesized using the microwave hydrothermalmethod at a low temperature. The effect of temperature and its performance. Differential thermal analysis and XRD phaseanalysis showed the mixed solution of Al(NO3)3 and Y(NO3)3 at pH=9 and C(Al3+)=0.42 mol·L−1. SEM, zeta potential, andparticle size analysis revealed that the microwave hydrothermal reaction temperature was 170 oC, and the high-purityultrafine YAG powder was calcined at 928 oC, which was lower than conventional calcination temperature. The synthesizedultrafine spherical YAG powder had a small particle size and a uniform distribution.
The technology and properties of sponge city permeable bricks prepared using refractory waste
Jieguang Song,Xueqing Yang,Ping Chen,Rongjin Liu,Deping Luo,Yuxuan Wei,Wenjin Yao,Jingjing Liu,Qing Zeng 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.4
With the widespread development of sponge city projects across the country, the use of industrial permeable bricks hasincreased dramatically. My country produces a large amount of refractory waste and pollutes the environment seriously. Wasterefractory insulation bricks are used as the main raw materials, and a small amount of auxiliary raw materials are added toprepare sponge urban permeable bricks through forming and sintering processes. Through performance tests, such asporosity, flexural strength, and water permeability coefficient, the effect of process parameters on the performance ofpermeable bricks is studied, the process parameters of using refractory waste are comprehensively optimized to preparesponge urban permeable bricks, and permeable bricks are prepared for the industrialization of high-quality industrial solidwaste. Brick provides reference. Through the experimental results and analysis, the following conclusions are drawn: the rawmaterial ratio of refractory brick waste: binder: foaming agent: sintering aid is 80:10:1:9. Slurry water mill foaming occurswhen the water to material ratio is 0.5, the ball milling speed is 80 r/min, and the ball milling time is 2 h; the foaming effectand molding performance are better. In the drying stage, drying at 45 oC for 12 h has the best molding effect. The sinteringsystem at 1,300 oC and holding time of 1 h has the best sintering performance. After optimizing the process, the porosity ofthe permeable bricks can reach 48.4%, the water permeability coefficient is 2.1×10^-2 cm/s, the national permeable brick hasA-level standard, and the compressive strength is 26.8 MPa.
The investigation of pH threshold value on the corrosion of steel reinforcement in concrete
Qi Pu,Yan Yao,Ling Wang,Xingxiang Shi,Jingjing Luo,Yifei Xie 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.3
The aim of this study is to investigate the pH threshold value for the corrosion of steel reinforcement in concrete. A method was designed to attain the pH value of the pore solution on the location of the steel in concrete. Then the pH values of the pore solution on the location of steel in concrete were changed by exposing the samples to the environment (CO25%, RH 40%) to accelerate carbonation with different periods. Based on this, the pH threshold value for the corrosion of steel reinforcement had been examined by the methods of half-cell potential and electrochemical impedance spectra (EIS). The results have indicated that the pH threshold value for the initial corrosion of steel reinforcement in concrete was 11.21. However, in the carbonated concrete, agreement among whether steel corrosion was initiatory determined by the detection methods mentioned above could be found.