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965 results on '"Yang, Jiandong"'

9. Solution and aging behavior of Mg-Al alloy modified by Nd-Gd

Author

YANG Jiandong

Subjects
modified magnesium alloy, solution and aging, rare earth phase, precipitate phase, Materials of engineering and construction. Mechanics of materials, TA401-492, Environmental engineering, TA170-171
Abstract

In order to investigate the effect of Nd, Gd composite modification and heat treatment process on the microstructure of Mg-8Al alloy, we analyzed the evolution behavior of Mg17Al12 closely related to mechanical properties of Mg alloys and rare earth phase. The microstructure of the specimens was characterized by metallographic microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM), and the morphology and distribution of β-Mg17Al12 and Al2RE in Mg-8Al-1Nd-1Gd alloy during solution treatment at 420 ℃ and aging precipitation at 210 ℃ were observed. The experimental results show that the eutectic of Mg alloy after modification with Nd and Gd, β-Mg17Al12 transforms from a continuous network to a fine discontinuous island and Al2RE phase with good thermal stability is produced at the grain boundary. The phase decomposition process of eutectic β-Mg17Al12 in solution treatment is continuous network-discontinuous island-spherical particles. Finally, a supersaturated α-Mg solid solution is formed, while Al2RE phase do not change before and after heat treatment. Lamellar and acicular aging precipitation β-Mg17Al12 is distributed at the grain boundary and in the grain, respectively and the precipitated β-Mg17Al12 presents fine and dispersed distribution characteristics under the modification of Nd and Gd.

Published
2023
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28. Does the upstream gate control scheme threaten the safety of extra-long pressurized water diversion tunnel: Gas–liquid evolution characteristics of the filling process.

Author

Ouyang, Chenxi, Zhao, Zhigao, Liu, ChengPeng, Zhao, Zhanpeng, Yin, Xiuxing, and Yang, Jiandong

Subjects
WATER tunnels, WATER levels, ENGINEERING design, MATHEMATICAL models, WATER diversion, COMPARATIVE studies, TUNNELS
Abstract

With the promotion of China's "National Water Networks" strategy, extra-long pressurized water diversion tunnels are increasingly implemented in trans-regional and trans-basin water diversion projects. Existing projects commonly employ middle or downstream gate control schemes, but setting the control gate at the upstream offers a new approach to mitigate the adverse effects of flow pattern changes and hydraulic inertia caused by gate operations. However, there is no precedent for a 200 km-extra-long pressurized water diversion tunnel worldwide, it is not clear whether deviating from established norms will create new problems, and how to illustrate the hydraulic evolution characteristics under this scheme is the primary challenge. Therefore, this study takes a follow-up project for China's South-to-North Water Diversion Project as the research object: (1) Modeling: establish a mathematical model of an extra-long pressurized water diversion tunnel based on the movement of gas–liquid interface; and (2) Simulating: analyze the transient process of two arrangement schemes (single-slope and variable-slope) under various operating conditions. The study reveals the characteristics of pressure distribution, flow rates, and water level variations along the tunnel, conducting a comparative analysis of different arrangement schemes. The findings demonstrate that, even under the most unfavorable assumption, the key indicators during the water filling process remain within the acceptable range specified by engineering design. Therefore, the adoption of the upstream gate control scheme for the extra-long water diversion tunnel is considered feasible. This research provides specific theoretical basis and technical support for the construction and operation of water diversion projects. [ABSTRACT FROM AUTHOR]

Published
2024
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29. Generating Personalized Titles Incorporating Advertisement Profile

Author

Wang, Jingbing, Hao, Zhuolin, Zhou, Minping, Chen, Jiaze, Zhou, Hao, Song, Zhenqiao, Wang, Jinghao, Yang, Jiandong, Ni, Shiguang, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Woeginger, Gerhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Jensen, Christian S., editor, Lim, Ee-Peng, editor, Yang, De-Nian, editor, Lee, Wang-Chien, editor, Tseng, Vincent S., editor, Kalogeraki, Vana, editor, Huang, Jen-Wei, editor, and Shen, Chih-Ya, editor

Published
2021
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