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12,210 results on '"Zhao, Zhen"'

467. A Lane-Changing Decision Model of Structured Roads Based on Optimized XGBoost Algorithm

Author

Zhao, Zhen, Ren, Xuemei, Wang, Haoyuan, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Jia, Yingmin, editor, Zhang, Weicun, editor, Fu, Yongling, editor, Yu, Zhiyuan, editor, and Zheng, Song, editor

Published
2022
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482. Longitudinal antibody response kinetics following SARS-CoV-2 messenger RNA vaccination in pregnant and nonpregnant persons

Author

Prabhu, Malavika, Yang, Yawei J., Johnston, Carrie D., Murphy, Elisabeth A., Ketas, Thomas J., Diaz-Tapia, Randy, Jurkiewicz, Magdalena, Racine-Brzostek, Sabrina, Mohammed, Iman, Sukhu, Ashley C., Singh, Sunidhi, Forlenza, Kimberly, Iyer, Sonali, Yee, Jim, Eng, Dorothy, Marks, Kristen, Zhao, Zhen, Klasse, Per Johan, Permar, Sallie, Moore, John P., and Riley, Laura E.

Published
2023
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492. Corner crack control for thin slab continuous casting of microalloyed steel

Author

Zhao-zhen CAI and Miao-yong ZHU

Subjects
microalloyed steel, thin slab continuous casting, corner cracks, mold, liquid core reduction, hard cooling, Mining engineering. Metallurgy, TN1-997, Environmental engineering, TA170-171
Abstract

Thin slab continuous casting and rolling process is an important way to produce hot-rolled strips. Recently, the process has been widely used to produce Nb/V/Ti/B bearing microalloyed steel. However, during the continuous casting of the thin slabs of the microalloyed steel, there are frequent cracks on the corners of the slabs, which would cause quality defects, such as scars and cracks at the edges of the hot-rolled coils. These defects are a common technical issue in the steel industry. In this paper, the characteristics of the microstructure and carbonitride precipitation of the thin slab corner of QStE380TM low carbon niobium–titanium bearing microalloyed steel, as well as the reduction of area of the steel under different cooling and tensile rates, were detected. Moreover, the evolutions of the temperature of the solidified shell in different structure molds and secondary cooling processes, as well as the stress of the thin slab surface during liquid core reduction, were numerically simulated. The results show that there is a significant third brittle temperature zone during continuous casting of microalloyed steel thin slabs, and the greater the deformation rate of the thin slab, the more significant the third brittle temperature zone is. Under the conventional thin slab continuous casting process, the cooling rate of the thin slab corners in the upper part of the mold and the secondary cooling zone from the mold exit to the liquid core reduction segment is lower than 5 °C·s−1, which is the key factor to lead a chain of niobium–titanium carbonitrides precipitate at the grain boundaries of the corners. As a result, the plasticity of the thin slab corners is greatly reduced. During the process of liquid core reduction, the low plasticity corners of the thin slab crack because of large deformation and stress. Applying the Gaussian concave curved surface mold, which the narrow face copper plates could efficiently compensate the shell shrinkage, the narrow face-foot roll zone hard cooling process can increase the cooling rates of the thin slab corners over 10 and 20 °C·s−1 in the mold and the narrow face-foot roller cooling zone, respectively. As a result, the carbonitrides precipitate in the thin slab corners disperses, and the stress of the thin slab corners reduces since the new mold promotes the metal flow of slab narrow surface broadsiding during the liquid core reduction. Finally, the cracking rate of the thin slab corners during the microalloyed steel thin slab casting has been reduced significantly.

Published
2022
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493. Abundant exact solutions of higher-order dispersion variable coefficient KdV equation

Author

Zhao Zhen and Pang Jing

Subjects
tension waves, fifth order variable coefficient kdv equation, hirota bilinear method, linear superposition principle, interaction solution, resonant multi soliton solution, Physics, QC1-999
Abstract

In this article, various exact solutions of the fifth-order variable coefficient KdV equation with higher-order dispersion term are studied. Because of the complexity of the exact solution of the variable coefficient t, it has a certain influence on the tension waves at the fluid interface on the gravity surface. First, the bilinear KdV equation is derived by using the Hirota bilinear method, and four mixed solutions consisting of positive quartic function, quadratic function, exponential function, and hyperbolic function are constructed. Second, the linear superposition principle is used to obtain the resonance multisoliton solution, and two cases are taken as examples to illustrate the study of resonance multi soliton solution. In addition, 3D images and contour images are drawn by mathematical symbol calculation and appropriate parameters, and the process of tension fluctuation is vividly explained by physical phenomena. The results obtained greatly expand the exact solution of the KdV equation in the existing literature and enable us to understand nonlinear dynamical systems more deeply.

Published
2022
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