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Stability of Semi-implicit Finite Volume Scheme for Level Set Like Equation

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Communications in Mathematical Research 2015年第4期31卷 351-361页

作者： Kim Kwang-il Son Yong-chol Ma fu-ming School of Mathematics Jilin University Department of Mathematics University of Science

We study numerical methods for level set like equations arising in image processing and curve evolution problems. Semi-implicit finite volume-element type schemes are constructed for the general level set like equation （image selective smoothing model） given by Alvarez et al. （Alvarez L, Lions P L, Morel J M. Image selective smoothing and edge detection by nonlinear diffusion II. SIAM J. Numer. Anal., 1992, 29： 845-866）. Through the reasonable semi-implicit discretization in time and co-volume method for space approximation, we give finite volume schemes, unconditionally stable in L∞ and W1＇2 （W1＇1） sense in isotropic （anisotropic） diffu- sion domain.

关键词： level set like equation semi-implicit finite volume scheme stability

Bifurcation in a Class of Planar Piecewise Smooth Systems with 3-parameters

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Communications in Mathematical Research 2014年第3期30卷 207-221页

作者： LIU YUAN-YUAN CHAI ZHEN-HUA Ma fu-ming School of Mathematics Jilin University

This paper is concerned with the bifurcation properties on the line of discontinuity of planar piecewise smooth systems. The existence of equilibria and periodic solutions with sliding motion in a class of planar piecewise smooth systems with 3-parameters is investigated in this paper using the theory of differential inclu-sion and tools of Poincar′e maps.

关键词： piecewise smooth system line of discontinuity equilibria periodic so-lution with sliding motion bifurcation

An Extension of Chebyshev's Maximum Principle to Several Variables

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Communications in Mathematical Research 2013年第4期29卷 363-369页

作者： Meng Zhao-liang Luo Zhong-xuan Ma fu-ming School of Mathematical Sciences Dalian University of Technology School of Software Dalian University of Technology

In this article, we generalize Chebyshev＇s maximum principle to several variables. Some analogous maximum formulae for the special integration functional are given. A sufficient condition of the existence of Chebyshe... 详细信息

关键词： cubature formula orthogonal polynomial Chebyshev's maximum prin-ciple nonstandard Gaussian quadrature

Chemical vapor deposition growth of crystal monolayer SnS2 with NaCl-assistant

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Chinese Physics B 2019年第11期28卷 360-363页

作者： Xiao-Xu Liu Da-Wei He Jia-Qi He Yong-Sheng Wang ming fu Key Laboratory of Luminescence and Optical Information Ministry of EducationInstitute of Optoelectronic TechnologyBeijing Jiao Tong UniversityBeijing 100044China

As an important member of the two-dimensional layers of metal dichalcogenides family, the two-dimensional(2 D)group IV metal chalcogenides(GIVMCs) have been attracting intensive attention. However, the growth of monolayer tin disulfide(SnS2) remains a great challenge contrasted to transition metal dichalcogenides, which have been studied quite maturely. Till date, there have been scant reports on the growth of large-scale and large-size monolayer SnS2. Here, we successfully synthesized monolayer SnS2 crystal on SiO2/Si substrates via NaCl-assisted CVD and the edge can be as long as 80 μm. Optical microscope, Raman spectroscopy, x-ray diffraction, atomic force microscopy(AFM), and energydispersion x-ray(EDX) were performed respectively to investigate the morphology, crystallographic structure, and optical property of the 2 D SnS2 nanosheets. In addition, we discussed the growing mechanism of the NaCl-assisted CVD method.

关键词： group IV metal chalcogenides tin disulfide two-dimensional materials chemical vapor deposition

Biquartic Finite Volume Element Method Based on Lobatto-Guass Structure

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Communications in Mathematical Research 2015年第4期31卷 320-332页

作者： Gao Yan-ni Chen Yan-li Ma fu-ming School of Mathematics Jilin University

In this paper, a biquartic finite volume element method based on Lobatto- Guass structure is presented for variable coefficient elliptic equation on rectangular partition. Not only the optimal H1 and L2 error estimates but also some superconvergent properties are available and could be proved for this method. The numerical results obtained by this finite volume element scheme confirm the validity of the theoretical analysis and the effectiveness of this method.

关键词： Lobatto-Guass structure biquartic finite volume element method er- ror estimate superconvergence

Stability analysis of free surface of soil between piles in fabricated recyclable foundation pit supporting structure

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Yantu Lixue/Rock and Soil Mechanics 2020年 41卷 299-305页

作者： Chen, Li-Chao Lin, Pei-Yuan Guo, Cheng-Chao Wang, fu-ming School of Civil Engineering Sun Yat-sen University Guangzhou 510275 China Zhuhai 519080 China Guangdong Provincial Key Laboratory of Oceanic Civil Engineering Sun Yat-sen University Guangzhou 510275 China Guangdong Provincial Research Center for Underground Space Exploitation Technology Guangzhou 510275 China

The stability of the free surface of the soil between the piles is of great significance for the engineering application of the assembled recyclable foundation pit support structure. In this paper, based on the calculation model of wedge-shaped body and the Terzaghi's theory on loosening earth pressure, considering the interaction between the soil and the pile-slab, the calculation formula of the ultimate supporting pressure of the free surface of the soil between the piles is derived from the limit equilibrium condition of the sliding mass. The calculated ultimate supporting pressure is compared with the numerical simulation results of three-dimensional finite element limit analysis to verify the rationality of the calculation method. The simple variable method was used to analyze the effects of soil internal friction angle φ, interface friction angle between soil and plates/piles δ, ground overload P0, spacing between piles B, relative excavation depth H/D, and unloading arch angle β on the ultimate support pressure. The research results can provide a theoretical basis for the soil support between the piles in the pile-slab support structure. © 2020, Science Press. All right reserved.

关键词： Piles

基于注意力机制的高光谱图像降维在纸质文物霉斑识别的研究

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光谱学与光谱分析 2025年第1期45卷 246-255页

作者：汤斌贺渝龙唐欢龙邹荣王建旭谭博文覃丹罗希玲赵明富重庆理工大学重庆市光纤传感与光电检测重点实验室重庆400054 馆藏文物有害生物控制研究国家文物局重点科研基地(重庆中国三峡博物馆) 重庆400060

纸质文物作为文物传承的重要工具,用于记录不同时期人类历史及人文风貌,其在保存过程中极易受到霉菌等微生物的侵害。霉菌会加速纤维素的降解,在纸张表面生成霉斑,并且散落的孢子会随空气流动大范围传播,增加其他纸质文物发生霉变的风... 详细信息

纸质文物作为文物传承的重要工具,用于记录不同时期人类历史及人文风貌,其在保存过程中极易受到霉菌等微生物的侵害。霉菌会加速纤维素的降解,在纸张表面生成霉斑,并且散落的孢子会随空气流动大范围传播,增加其他纸质文物发生霉变的风险。因此,定期对纸质文物进行霉斑检测对了解纸质文物现状和纸质文物修复至关重要。高光谱成像技术是一种非接触性、非破坏性的检测技术,能同时获得空间数据和光谱数据,与计算机技术结合可以实现纸质文物的大批次实时无损检测。针对黑曲霉这一广泛出现的霉菌,提出一种基于注意力机制的高光谱数据降维方法,通过采集其高光谱数据,实现了高光谱冗余数据的自适应预处理。采集了来自重庆中国三峡博物馆提供的20份纸质文物黑曲霉霉斑样本,使用ENVI软件分析得出在413~855 nm波段范围内,黑曲霉霉斑感染区域和健康区域的平均光谱曲线,平均反射率差异明显;在855~1021 nm波段范围内,黑曲霉霉斑感染区域和墨迹区域的平均光谱曲线,平均反射率差异明显。文中将所提出方法与传统主成分分析和独立成分分析预处理方法分别处理原始高光谱数据,并将结果在经典U-Net、SegNet、DeepLabV3+和PSPNet四个语义分割网络上进行了对比。结果表明,该算法预处理的数据在U-Net和SegNet经典网络中有明显优势,相较于主成分分析法和独立成分分析法,霉斑识别精度取得了较大提升达到89.49%和88.46%,验证了本文所提出算法的有效性,为文物保护领域提供有效的支撑和新的思路。

关键词：高光谱数据预处理霉斑识别纸质文物注意力机制图像分割

Study on the Anisotropy of Meniscus in the Growing Sapphire

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Chinese Journal of Aeronautics 2006年第B12期19卷 78-81页

作者： YAO Tai ZUO Hong-bo HANJie-cai MENG Song-he ZHANG ming-fu LI Chang-qing Grigoryan Benik Center for Composite Materials Harbin Institute of Technology Harbin 150006 China

This study is aimed at predicting the relationship between the meniscus and the quality of the sapphire crystals produced by the micro-pulling and shoulder at cooled center （SAPMIC） technique. As with different orientations, the shapes of the meniscus vary, so an investigation into the anisotropy of the meniscus shapes is very important for the final quality of the sapphire crystal. An effective model to describe meniscus shapes and their formation process has been presented. The model has been applied to a sapphire crystal of 200 mm diameter in order to check its reliability. The results show that the model proves to be useful for forecasting the final shapes of the sapphire crystal made by the SAPMIC technique.

关键词： anisotropy meniscus simulation sapphire

Natural populations of lactic acid bacteria in douchi from Yunnan Province,China

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2012年第4期13卷 298-306页

作者： Chen-jian LIU fu-ming GONG Xiao-ran LI Hai-yan LI Zhong-hua ZHANG Yue FENG Hiroko NAGANO State Key Laboratory of Food Science and Technology Jiangnan UniversityWuxi 214122China Laboratory ofApphed Mierobtology Faculty ofLife Scwnee and TechnologyKunmmg Umversity of Sctence and TechnologyKunming 650500Chin Basic Department Dehong Vocational CollegeMangshi 678499China Faculty of Education Gifu UniversityGifu 501-1193Japan

This research was aimed at isolating and identifying the predominant lactic acid bacteria(LAB) in the traditional Chinese salt-fermented soybean food,douchi,from Yunnan,*** predominant LAB present were isolated and identified by conventional culture-dependent methods combined with molecular biological *** hundred and sixty isolates were obtained from thirty kinds of traditional fermented douchi from six cities and counties in Yunnan,and those strains were divided into twelve groups by their morphological and biochemical *** on 16S ribosomal DNA(rDNA) sequencing and analysis,56 representative strains were identified as belonging to 6 genera and 14 species:Lactobacillus(4 spp.),Weissella(3 spp.),Pediococcus(2 spp.),Staphylococcus(2 spp.),Enterococcus(1 sp.),and Bacillus(2 spp.).The results show that douchi contains a large natural population of LAB of diverse composition from which some strains could be selected as starters for functional fermented *** is the first study on the original douchi from Yunnan,and the results suggest that it may be a useful source for the isolation of *** study has also laid a foundation for further research on developing functional douchi products.

关键词： Fermented food Douchi Lactic acid bacteria Culture-dependent methods 16S rDNA