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1,908 results on '"Wang, Xianfeng"'

2. Generalized Alexandrov theorems in spacetimes with integral conditions

Author

Kwong, Kwok-Kun and Wang, Xianfeng

Subjects
Mathematics - Differential Geometry, Mathematical Physics, 53C40, 53C50, 53C65
Abstract

We investigate integral conditions involving the mean curvature vector $\vec{H}$ or mixed higher-order mean curvatures, to determine when a codimension-two submanifold $\Sigma$ lies on a shear-free (umbilical) null hypersurface in a spacetime. We generalize the Alexandrov-type theorems in spacetime introduced in \cite{wang2017Minkowski} by relaxing the curvature conditions on $\Sigma$ in several aspects. Specifically, we provide a necessary and sufficient condition, in terms of a mean curvature integral inequality, for $\Sigma$ to lie in a shear-free null hypersurface. A key component of our approach is the use of Minkowski formulas with arbitrary weight, which enables us to derive rigidity results for submanifolds with significantly weaker integral curvature conditions., Comment: 19 pages

Published
2023

4. Analysis of Improving Generator Power Quality and Unit Stability Based on Generator Short Circuit Drying Temperature Rise Test

Author

Lei, Xule, Wang, Xianfeng, Pang, Hongqiang, Liu, Deyi, He, Xinlin, Li, Zhihua, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, 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, 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, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Panigrahi, Bijaya Ketan, 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, Tan, Kay Chen, Series Editor, Yang, Qingxin, editor, Li, Zewen, editor, and Luo, An, editor

Published
2024
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10. Hypersurfaces of $\mathbb{S}^2\times\mathbb{S}^2$ with constant sectional curvature

Author

Li, Haizhong, Vrancken, Luc, Wang, Xianfeng, and Yao, Zeke

Subjects
Mathematics - Differential Geometry, 53C42, 53B25
Abstract

In this paper, we classify the hypersurfaces of $\mathbb{S}^2\times\mathbb{S}^2$ with constant sectional curvature. By applying the so-called Tsinghua principle, which was first discovered by the first three authors in 2013 at Tsinghua University, we prove that the constant sectional curvature can only be $\frac{1}{2}$ and the product angle function $C$ defined by Urbano is identically zero. We show that any such hypersurface is a parallel hypersurface of a minimal hypersurface in $\mathbb{S}^2\times\mathbb{S}^2$ with $C=0$, and we establish a one-to-one correspondence between the involving minimal hypersurface and the famous ``sinh-Gordon equation'' $$ (\frac{\partial^2}{\partial u^2}+\frac{\partial^2}{\partial v^2})h =-\tfrac{1}{\sqrt{2}}\sinh(\sqrt{2}h). $$ As a byproduct, we give a complete classification of the hypersurfaces of $\mathbb{S}^2\times\mathbb{S}^2$ with constant mean curvature and constant product angle function $C$., Comment: 24 pages

Published
2023

12. Influence of Countersink Fillet Radius on Mechanical Performance of CFRP/Al Bolted Joints

Author

WANG Xianfeng, ZOU Fan, LIU Chang, AN Qinglong, CHEN Ming

Subjects
carbon fiber reinforced polymer (cfrp), countersink, fillet radius, mechanical joint, finite element method, Engineering (General). Civil engineering (General), TA1-2040, Chemical engineering, TP155-156, Naval architecture. Shipbuilding. Marine engineering, VM1-989
Abstract

Carbon fiber reinforced polymer (CFRP) and aluminum alloys (Al) are widely used in the new generation of commercial aircraft due to their excellent mechanical/physical properties. CFRP/Al countersink bolted structures are important connection forms, where the radius of the countersink fillet affects the mechanical connection performance. The countersink fillet radius is an important factor affecting the mechanical performance of bolted joints. In this paper, the countersink fillet radius is controlled by specially-designed drill-countersink tools with different countersink fillet radii. Meanwhile, the finite element model based on the progressive damage method of composite material is established and utilized to simulate the mechanical performance of different composite/metal bolted joints. The failure mechanism of CFRP/Al bolted joints is analyzed. The results show that the countersink fillet radius can be effectively controlled by specially-designed drill-counterbore tools. The ultimate strength of bolted joints with dimple in the CFRP layer is higher than that in the aluminum alloy layer. In terms of the countersink fillet radius, both CFRP and aluminum alloy materials have the maximum strength when the countersink fillet radius is 1.0 mm. That is, the countersink fillet radius should be slightly larger than the bolt fillet radius, which is conducive to a better mechanical performance.

Published
2024
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33. Coupled atmosphere-ice-ocean dynamics during Heinrich Stadial 2

Author

Dong, Xiyu, Kathayat, Gayatri, Rasmussen, Sune O, Svensson, Anders, Severinghaus, Jeffrey P, Li, Hanying, Sinha, Ashish, Xu, Yao, Zhang, Haiwei, Shi, Zhengguo, Cai, Yanjun, Pérez-Mejías, Carlos, Baker, Jonathan, Zhao, Jingyao, Spötl, Christoph, Columbu, Andrea, Ning, Youfeng, Stríkis, Nicolás M, Chen, Shitao, Wang, Xianfeng, Gupta, Anil K, Dutt, Som, Zhang, Fan, Cruz, Francisco W, An, Zhisheng, Lawrence Edwards, R, and Cheng, Hai

Subjects
Earth Sciences, Physical Geography and Environmental Geoscience, Geology, Climate Action
Abstract

Our understanding of climate dynamics during millennial-scale events is incomplete, partially due to the lack of their precise phase analyses under various boundary conditions. Here we present nine speleothem oxygen-isotope records from mid-to-low-latitude monsoon regimes with sub-centennial age precision and multi-annual resolution, spanning the Heinrich Stadial 2 (HS2) - a millennial-scale event that occurred at the Last Glacial Maximum. Our data suggests that the Greenland and Antarctic ice-core chronologies require +320- and +400-year adjustments, respectively, supported by extant volcanic evidence and radiocarbon ages. Our chronological framework shows a synchronous HS2 onset globally. Our records precisely characterize a centennial-scale abrupt "tropical atmospheric seesaw" superimposed on the conventional "bipolar seesaw" at the beginning of HS2, implying a unique response/feedback from low-latitude hydroclimate. Together with our observation of an early South American monsoon shift at the HS2 termination, we suggest a more active role of low-latitude hydroclimate dynamics underlying millennial events than previously thought.

Published
2022

34. Performance of polycarboxylate superplasticisers in seawater-blended cement: Effect from chemical structure and nano modification

Author

Ren Jun, Yan Shuo, Fang Yunhui, Tian Zhenhe, Li Hao, Guo Jinyi, Xing Feng, Fan Yiding, Wang Xianfeng, and Ren Zengle

Subjects
polycarboxylate superplasticiser, nanosilica, rheological behaviour, seawater, molecular architecture, adsorption, Technology, Chemical technology, TP1-1185, Physical and theoretical chemistry, QD450-801
Published
2023
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46. Self-similar solutions to fully nonlinear curvature flows by high powers of curvature

Author

Gao, Shanze, Li, Haizhong, and Wang, Xianfeng

Subjects
Mathematics - Differential Geometry
Abstract

In this paper, we investigate closed strictly convex hypersurfaces in $\mathbb{R}^{n+1}$ which shrink self-similarly under a large family of fully nonlinear curvature flows by high powers of curvature. When the speed function is given by powers of a homogeneous of degree $1$ and inverse concave function of the principal curvatures with power greater than $1$, we prove that the only such hypersurfaces are round spheres. We also prove that slices are the only closed strictly convex self-similar solutions to such curvature flows in the hemisphere $\mathbb{S}^{n+1}_{+}$ with power greater than or equal to $1$., Comment: 23 pages, revised version, some typos are corrected, to appear in Crelle's Journal

Published
2020

47. Shifted inverse curvature flows in hyperbolic space

Author

Wang, Xianfeng, Wei, Yong, and Zhou, Tailong

Subjects
Mathematics - Differential Geometry, Mathematics - Analysis of PDEs, 53E10, 53C21
Abstract

We introduce the shifted inverse curvature flow in hyperbolic space. This is a family of hypersurfaces in hyperbolic space expanding by $F^{-p}$ with positive power $p$ for a smooth, symmetric, strictly increasing and $1$-homogeneous curvature function $f$ of the shifted principal curvatures with some concavity properties. We study the maximal existence and asymptotical behavior of the flow for horo-convex hypersurfaces. In particular, for $0

Published
2020
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