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28 results on '"Lin, Yujin"'

3. Some topological properties of topological rough groups

Author

Lin, Fucai, Sun, Qianqian, Lin, Yujin, and Li, Jinjin

Subjects
Mathematics - General Topology, Mathematics - Group Theory, Primary: 22A05, 54A05. Secondary: 03E25
Abstract

Let $(U, R)$ be an approximation space with $U$ being non-empty set and $R$ being an equivalence relation on $U$, and let $\overline{G}$ and $\underline{G}$ be the upper approximation and the lower approximation of subset $G$ of $U$. A topological rough group $G$ is a rough group $G=(\underline{G}, \overline{G})$ endowed with a topology, which is induced from the upper approximation space $\overline{G}$, such that the product mapping $f: G\times G\rightarrow \overline{G}$ and the inverse mapping are continuous. In the class of topological rough groups, the relations of some separation axioms are obtained, some basic properties of the neighborhoods of the rough identity element and topological rough subgroups are investigated. In particular, some examples of topological rough groups are provided to clarify some facts about topological rough groups. Moreover, the version of open mapping theorem in the class of topological rough group is obtained. Further, some interesting open questions are posed., Comment: 19 pages

Published
2020

14. The deformation analysis of friction stir welding with different clamping distances for large thin-walled joints

Author

Gao, Chang, Yu, Haidong, Gu, Bin, and Lin, Yujin

Subjects
General Materials Science, Condensed Matter Physics
Abstract

Clamping scheme may change the local stiffness and affect the welding deformation which is very important for the large thin-walled joints connected by friction stir welding with heavy load and heat production. In this paper, the welding experiments of large thin-walled joints were conducted and the numerical simulation model is established based on three-dimensional stress mapping method. The accuracy of the numerical model is verified and welding deformation with various clamping distances is discussed. The restraint intensity index is employed to describe the influence of clamping distance on the stiffness of welding seam and welding deformation. The mechanism of welding deformation with the effect of clamping distance is well revealed by the analysis of welding stress and restraint intensity.

Published
2023
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20. Acousto-electric attenuation in a layered structure analyzed by the transmission line technique

Author

Wang, Wen-Chung and Lin, Yujin

Subjects
Semiconductor films -- Research, Sound -- Research, Business, Electronics, Electronics and electrical industries
Abstract

A study was conducted to analyze a structure of an infinitesimally thin semiconductor film deposited on a SAW substrate without an isolation layer in-between. Device parameters were selected so that the charge relaxation time was much smaller than the duration of the wavelength. Results indicated that the transmission line framework can be effectively utilized to examine the acousto-electric interaction in a multimedium, coupled-layer system.

Published
1999

26. A Modified ZnO Film Model for Calculating Elastic and Piezoelectric Properties

Author

Wu Xizhang, Zhao Mingzhou, Zhang Xiaozhong, Lin Yujin, and Qian Zenxing

Subjects
Diffraction, Materials science, Condensed matter physics, business.industry, General Engineering, Crystal structure, Expected value, Piezoelectricity, Crystal, Optics, X-ray crystallography, Thin film, business, Single crystal
Abstract

Abstmct-A modified ZnO film model to calculate the elastic and pi- ezoelectric constants and the SAW velocities of ZnO film (c-axis ori- ented) substrate layer structure is proposed. The influences of the ran- dom orientation and lattice distortion have been taken into account. Compared to the traditional single crystal model, the theoretical results of the modified model fit better with the experimental values of a laser- probe measuring system. minor effect on the SAW properties of the ZnO substrate layer structure when it is not larger than 3 O. In the present case the mean is less than l"; therefore, for simplicity it is assumed to be zero, and only the effect of U (o is equal to 3" from the X-ray diffraction pattern) is taken into ac- count. In our model, the ZnO film is treated as a collec- tion of many monocrystal columns. The orientation 7 of the c-axis of each crystal column has the value within ( -T/ 2, 7r/2) on both the y-z and x-z planes. The material pa- rameters of the monocrystal column with the c-axis ori- entation of 17 can be calculated by assuming that 17 follows the normal distribution Since all the monocrystal columns with c-axis orientations contribute to the material parameters, their mathematical expectation can be taken as the material parameters of ZnO film. The average can be obtained by integrating with respect to 7 twice, first in the x-z plane and then in the y- z plane. Since 7 is a two-dimensional variable, the first integration process in the x-y plane can be stated as fol- lows

Published
1985

28. Genomic evolution of BA.5.2 and BF.7.14 derived lineages causing SARS-CoV-2 outbreak at the end of 2022 in China.

Author

Zhu W, Wang X, Lin Y, He L, Zhang R, Wang C, Zhu X, Tang T, and Gu L

Subjects
Humans, Genomics, Disease Outbreaks, China epidemiology, Evolution, Molecular, SARS-CoV-2 genetics, COVID-19 epidemiology
Abstract

Since the end of 2022, when China adjusted its COVID-19 response measures, the SARS-CoV-2 epidemic has rapidly grown in the country. It is very necessary to monitor the evolutionary dynamic of epidemic variants. However, detailed reports presenting viral genome characteristics in China during this period are limited. In this study, we examined the epidemiological, genomic, and evolutionary characteristics of the SARS-CoV-2 genomes from China. We analyzed nearly 20,000 genomes belonging to 17 lineages, predominantly including BF.7.14 (22.3%), DY.2 (17.3%), DY.4 (15.5%), and BA.5.2.48 (11.9%). The Rt value increased rapidly after mid-November 2022, reaching its peak at the end of the month. We identified forty-three core mutations in the S gene and forty-seven core mutations in the ORF1ab gene. The positive selection of all circulating lineages was primarily due to non-synonymous substitutions in the S1 region. These findings provide insights into the genomic characteristics of SARS-CoV-2 genomes in China following the relaxation of the 'dynamic zero-COVID' policy and emphasize the importance of ongoing genomic monitoring., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhu, Wang, Lin, He, Zhang, Wang, Zhu, Tang and Gu.)

Published
2023
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