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- 저자 : Keqing Han (검색결과 3 건)
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Hu Yafei,Li Keqing,Zhang Bo,Han Bin 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.5
Solid waste filling is an important development direction for filling mining technology. This paper proposes to use waste rock and aeolian sand as aggregates to fill the underground extraction area in order to reduce the environmental damage of related waste solid. The experiments are optimized by response surface methodology and multivariate nonlinear response models are constructed to investigate the effects of different factors on uniaxial compressive strength (UCS) of concrete-like material (CLM). The performance of different swarm intelligence optimization algorithms is analyzed and combined with support vector regression model (SVR) to construct an intelligent prediction model for UCS. The results show that the packing density has a maximum value of 0.74 when the proportion of waste rock is around 0.6. The response model constructed in this paper has a P-value < 0.01 and R2 > 0.8, which indicates its high significance and goodness of fit. The UCS of CLM increases with the increase of cement content and slurry mass fraction, while it also increases and then decreases with the increase of proportion of waste rock. The ratio of waste rock and aeolian sand will affect the compactness of cemented structure. The better the ratio, the higher the average grey value of the cemented structure, the more compactness the cemented structure. The whale optimization algorithm-SVR model constructed in this paper has a prediction accuracy of more than 99% for UCS of CLM, which achieves high accuracy and fast prediction of UCS under multifactor conditions.
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Synthesis and Characterization of a Novel Preceramic Polymer for SiBNC Ceramic Fibers
Chenyu Zhang,Yong Liu,Yongjie Cui,Minqiang Jiang,Keqing Han,Hui Zhang,Muhuo Yu 한국섬유공학회 2018 Fibers and polymers Vol.19 No.5
A new approach for the synthesis of polymer precursor for quaternary SiBNC fibers is presented. The inexpensive, commercially available reactants n-propylamine (C3H7NH2), trichlorosilane (SiHCl3) and boron trichloride (BCl3) were used in a simple one-step reaction. The reaction mainly involved the co-polymerization between Si-Cl, B-Cl and N-CH2CH2CH3 with C3H7NH2 evaporation. Characterization of synthesized polymer was performed by FT-IR and NMR. The polymer has a relatively linear-chain chemical structure, and could be easily converted into flexible green fibers by melt-spun with diameter of 24 μm. After pyrolysis process at 1000 oC under nitrogen atmosphere, SiBNC ceramic fibers were obtained with a diameter of about 19 μm. Those fibers showed average tensile strength of 1.05 GPa and it remained in the amorphous state up to 1600 oC, which made them as the promising candidates for reinforcements in ceramic matrix composites for hightemperature application.
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Elagib Tienah H. H.,Hassan Elwathig A. M.,Liu Baihua,Han Keqing,Yu Muhuo 한국탄소학회 2020 Carbon Letters Vol.30 No.3
The composite PAN fbers which incorporated with CNTs and Titania were prepared by mean of wet spinning. These fbers were then pre-oxidized with microwave heating in an air atmosphere. A combination of characterizations was carried out to study the impact of nanoparticles fllers on the properties of as-spun fbers and their performance during the microwave pre-oxidation. The addition of an equal amount of fllers made obvious changes in the chemical and crystalline structure, consequently improves the strength, and this could lower the capability to creep over a wide range of temperatures in the subsequent processes. FTIR and NMR analyses results of the pre-oxidized fbers exhibited clear changes in the PAN structure, where the dehydrogenation reaction and the degree of cyclization were investigated. Additional confrmation of the occur�rence of cyclization reaction was achieved by XRD and thermal analysis. According to the TGA results, the pre-oxidized CNT1 /Ti-PAN fbers exhibit greater thermal stability suggesting high carbon content and good quality could result in the dependent carbon fbers.
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