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134 results on '"Feng, Junwei"'

1. Research on the Transfer Effect of Manufacturing Industry in Beijing-Tianjin-Hebei Urban Agglomeration Under the Background of Carbon Peak

Author

Feng, Junwei, Liu, Jianghui, Che, Huichun, Barbosa-Povoa, Ana Paula, Editorial Board Member, de Almeida, Adiel Teixeira, Editorial Board Member, Gans, Noah, Editorial Board Member, Gupta, Jatinder N. D., Editorial Board Member, Heim, Gregory R., Editorial Board Member, Hua, Guowei, Editorial Board Member, Kimms, Alf, Editorial Board Member, Li, Xiang, Editorial Board Member, Masri, Hatem, Editorial Board Member, Nickel, Stefan, Editorial Board Member, Qiu, Robin, Editorial Board Member, Shankar, Ravi, Editorial Board Member, Slowiński, Roman, Editorial Board Member, Tang, Christopher S., Editorial Board Member, Wu, Yuzhe, Editorial Board Member, Zhu, Joe, Editorial Board Member, Zopounidis, Constantin, Editorial Board Member, Li, Menggang, editor, Guowei, Hua, editor, Huang, Anqiang, editor, Fu, Xiaowen, editor, and Chang, Dan, editor

Published
2024
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11. Cultivation of Core Literacy of Physical Education Professionals in Private Colleges and Universities Based on the Background of Data Mining

Author

Feng Junwei

Subjects
association rules, xgboost algorithm, apriori algorithm, confidence principle, talent core literacy, 62n01, Mathematics, QA1-939
Abstract

The purpose of this paper is to analyze the main types of core literacy of sports professionals in colleges and universities using association rules and the XGBoost algorithm. Combined with the confidence rule in association analysis, it finds out the minimum support degree of all the core qualities that satisfy the core qualities of sports professionals in colleges and universities. The efficiency of modeling talent demand can be improved by using the Apriori algorithm. Adding new regression trees sequentially based on the original model using the XGBoost algorithm. The college sports talent demand model was constructed by combining association rules and the XGBoost algorithm. Based on the results, composite talents, professional talents, and application talents are the main types of sports professional talent cultivation positioning. The cultivation ratio of sports composite talents in University A is 0.7, and the cultivation ratio of application composite talents is 0.6. The school’s requirements for sports talent’s ability are the highest, resulting in a cultivation ratio of 0.75 for sports talent. This study promotes, to a certain extent, the cultivation of sports professionals in colleges and universities.

Published
2024
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23. Effect of V-Mn-Cr inoculant on microstructure and mechanical properties of grey cast iron

Author

Ji, Lie, Du, Xueshan, Cao, Wenbo, Zhao, Jingyu, Sun, Yufu, Zhu, TengZhong, Feng, JunWei, and Xing, Beibei

Abstract

ABSTRACTIn this study, the effects of different composition V-Mn-Cr inoculants on the microstructure and mechanical properties of GCI were investigated through Optical microscope (OM), Scanning electron microscope (SEM), Energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), etc. The results showed that the optimum quantity of inoculant was 7% V, 1% Mn and 6% Cr, and compared with the commercial inoculant samples, the tensile strength, Brinell hardness, and elastic modulus of the V-Mn-Cr inoculant samples increased by 16.7%, 14.2%, and 12.8%, respectively. V-Mn-Cr inoculants were found to refine austenite, graphite, pearlite and eutectic cells size, reduce pearlite lamellar spacing, and increase pearlite and eutectic cells number, thus improving mechanical properties. In addition, graphite nucleation substance may consist of oxides (SiO2, FeO, Cr2O3), carbides (SiC, TiC), sulfides (MnS, FeS), and XO·SiO2silicates (X: Mn, Fe, Ca).

Published
2023
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30. Effect of Solidification Rate on Microstructure and Mechanical Characteristic of Gray Cast Iron

Author

Ji, Lei, Du, Xueshan, Sun, Yufu, Zhu, Tengzhong, and Feng, Junwei

Abstract

In this study, various solidification rates were achieved by controlling the wall thickness to improve the hardness properties of gray cast iron (GCI). The effects of solidification rate on the microstructure and mechanical properties of GCI were investigated through Optical microscope, Scanning electron microscope, Thermal analysis, etc. Experimental results showed that the hardness improved as the solidification rate increased. Higher solidification rates were found to refine austenite, graphite, pearlite and eutectic cell size, reduce pearlite lamellar spacing, and increase pearlite and eutectic cell count. The increasing solidification rate resulted in the carbon released by the austenite accumulation along the austenite dendrites, which caused type D graphite formation. In addition, it was also found that the primary dendrite arm spacing (DAS), secondary dendrite arm spacing (SDAS) and eutectic cell size decreased as the hardness increased. Thermal analysis revealed that the increased solidification rate reduced the austenite precipitation, eutectic nucleation and eutectic minimum temperature, resulting in an improvement of the undercooling, thus accelerating the solidification and crystallization process.

Published
2023
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43. Na2La2B10O19: a new lanthanum sodium borate with infinite 2D layer 2∞[B10O19]8− and moderate birefringence.

Author

Wu, Chengfa, Feng, Junwei, and Yu, Feng

Subjects
*BORAX, *BIREFRINGENCE, *LANTHANUM, *INFINITE groups, *SPACE groups, *RARE earth metals
Abstract

A new rare earth borate Na2La2B10O19 was successfully synthesized by spontaneous crystallization in a high temperature solution. It crystallizes in the centrosymmetric (CS) space group C2/c with an infinite two-dimensional (2D) double layer which is composed of the fundamental building block (FBB) [B5O12]9−. The calculated birefringence of the compound is 0.06 @1064 nm which mainly originates from the contributions of the B–O anion group according to the first-principles study. [ABSTRACT FROM AUTHOR]

Published
2021
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44. Na2Rb2SrB18O30 with [B9O19]11− fundamental building block consisting of three [B3O7]5− groups.

Author

Zheng, Jingjing, Zhang, Ting, Feng, Junwei, An, Donghai, Bai, Chunyan, and Sun, Yi

Subjects
RUBIDIUM, CRYSTAL optics, X-ray diffraction, ALKALINE earth metals, SPACE groups, SINGLE crystals
Abstract

A new sodium rubidium strontium borate, Na2Rb2SrB18O30, has been successfully synthesized via the high temperature solution method and characterized by single crystal X ray diffraction. The compound crystallizes in the monoclinic space group P21/c (No. 14) with the following cell parameters: a=8.464(5) Å, b=8.516(5) Å, c=17.110(10) Å, β=92.281(8)°, V=1232.3(12) Å3, Z=2. The fundamental building block (FBB) of Na2Rb2SrB18O30 is [B9O19]11−, which consists of three [B3O7]5− groups bridged by oxygen atoms. The FBB connects with adjacent ones through the terminal oxygen atoms condensed into a three dimensional (3D) 3∞[B9O15] network with three types of channels, and two of them are occupied by Rb+ and Sr2+ cations. Besides, the structure comparison and categorization between the borates with [B9O19]11− FBB were investigated via the topological analysis for the first time. Also, theoretical analyses of the band structures and partial densities of states (PDOS) calculations were carried out to elaborate the relationship between crystal structures and optical properties by first‐principles calculation. [ABSTRACT FROM AUTHOR]

Published
2021
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