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Approximation of eigenvalues below the essential spectra of singular second-order symmetric linear difference equations

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Science China Mathematics 2017年第9期60卷 1661-1678页

作者： LIU Yan shi yuming Department of Mathematics Shandong UniversityJinan 250100China

This paper is concerned with approximation of eigenvalues below the essential spectra of singular second-order symmetric linear difference equations with at least one endpoint in the limit point case. A sufficient condition is firstly given for that the k-th eigenvalue of a self-adjoint subspace （relation） below its essential spectrum is exactly the limit of the k-th eigenvalues of a sequence of self-adjoint subspaces. Then, by applying it to singular second-order symmetric linear difference equations, the approximation of eigenvalues below the essential spectra is obtained, i.e., for any given self-adjoint subspace extension of the corresponding minimal subspaee, its k-th eigenvalue below its essential spectrum is exactly the limit of the k-th eigenvalues of a sequence of constructed induced regular self-adjoint subspace extensions.

关键词： difference equation approximation eigenvalue limit point case self-adjoint subspace

Discrete chaos in Banach spaces

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Science China Mathematics 2005年第2期48卷 222-238页

作者： shi yuming CHEN Guanrong Department of Mathematics Shandong UniversityJina 250100China Department of Electronic EngineeringCity University of Hong KongChina

This paper is concerned with chaos in discrete dynamical systems governed by continuously Frech@t differentiable maps in Banach spaces. A criterion of chaos induced by a regular nondegenerate homoclinic orbit is established. Chaos of discrete dynamical systems in the n-dimensional real space is also discussed, with two criteria derived for chaos induced by nondegenerate snap-back repellers, one of which is a modified version of Marotto's theorem. In particular, a necessary and sufficient condition is obtained for an expanding fixed point of a differentiate map in a general Banach space and in an n-dimensional real space, respectively. It completely solves a long-standing puzzle about the relationship between the expansion of a continuously differentiable map near a fixed point in an n-dimensional real space and the eigenvalues of the Jacobi matrix of the map at the fixed point.

关键词： chaos, discrete dynamical system, Banach space, Marotto's theorem.

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健康鞋产业概述及中国健康鞋发展趋势探讨

中国皮革 2024年第5期53卷 69-72,81页

作者：施禹名崔同占蒋振刚孙天赦施凯温州职业技术学院浙江温州325000

人们健康意识的逐渐增强与足部疾病发病率的增加使得人们对健康鞋的需求逐渐提高。本文将健康鞋分为大众康养类与医疗辅助类两类,对两类健康鞋在国际与国内的发展现状进行了调研与综述。进一步的,结合中国宏观背景与国际上健康鞋的先进... 详细信息

人们健康意识的逐渐增强与足部疾病发病率的增加使得人们对健康鞋的需求逐渐提高。本文将健康鞋分为大众康养类与医疗辅助类两类,对两类健康鞋在国际与国内的发展现状进行了调研与综述。进一步的,结合中国宏观背景与国际上健康鞋的先进成果,总结了待突破的重点问题,聚焦了新兴的研究方向,并对中国健康鞋未来的发展趋势进行了探讨。

关键词：健康鞋制鞋行业结构设计材料创新智能化

Dual metal ions/BNQDs boost PMS activation over copper tungstate photocatalyst for antibiotic removal:Intermediate,toxicity assessment and mechanism

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Journal of Materials Science & Technology 2024年第3期170卷 11-24页

作者： Ruyao Chen Haiyue Zhang yuming Dong Haifeng shi School of Science Jiangnan UniversityWuxi214122China The Key Laboratory of Synthetic and Biological Colloids Ministry of EducationJiangnan UniversityWuxi214122China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing210093China

In the metal-based peroxymonosulfate(PMS)activation process,the sluggish surface redox cycle of metal ions generally hampered the efficiency of PMS activation for pollutant ***,Codoped CuWO 4/BN quantum dots(CW/Co/BNQDs)photocatalysts were developed to realize Cu^(2+)/Cu+and Co^(2+)/Co^(3+)dual ions redox cycles for PMS activation,which would facilitate the tetracycline(TC)***/4Co/2BNQDs could degrade 94.8%TC within 30 min in PMS/Vis system,and the apparent rate constant of CW/4Co/2BNQDs was 2.7 times and 1.2 times higher than those of CW and CW/4Co,*** improved TC degradation performance could be attributed to the synergetic effect between BNQDs and dual redox cycles.X-ray photoelectron spectroscopy(XPS)spectra of samples before and after the reaction demonstrated that BNQDs were beneficial for accelerating the Cu^(2+)/Cu+and Co^(2+)/Co^(3+)redox cycles in CW/4Co/2BNQDs,further boosting the activation of PMS in TC *** of different radical scavengers revealed that the SO_(4)^(·−)/·OH/h+/^(1)O_(2)reactive species participated in the PMS activation for the TC degradation *** possible TC degradation pathway and intermediate toxicity were detailed *** addition,CW/4Co/2BNQDs exhibited outstanding photocatalytic activity over five consecutive cycles,which illustrated that it was supposed to be a reliable PMS activator over antibiotic elimination for practical *** this work shed new light on constructing dual redox cycles for efficient PMS activation.

关键词： Dual redox cycles Photocatalysis Peroxymonosulfate BN quantum dots Toxicity assessment

DIRECT CONSTRUCT OF PERIODIC SOLUTIONS TO PERTURBED KLEIN-GORDON EQUATIONS BY NEWTON ITERATION

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Chinese Annals of Mathematics,Series B 2000年第3期21卷 297-322页

作者： shi yuming (Department of Mathematics, Fudan University, Shanghai 200433, China. E-mail: ymshi@***) Department of Mathematics Fudan University Shanghai 200433 China

By introducing the block estimate technique and directly using the Newton iteration method, the author constructs Cantor families of time periodic solutions to a class of nonlinear wave equations with periodic boundary conditions. The Lyapunov-Schmidt decomposition used by J. Bourgain, W. Craig and C. E. Wayne is avoided. Thus this work simplifies their framework for KAM theory for PDEs.

关键词： Klein-Gordon equation Periodic solution Newton iteration

Experimental study on the sandstone abrasiveness via mineral composition and microstructure analysis

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Petroleum 2024年第3期10卷 440-445页

作者： Xiangchao shi Yang Tang Shuai Chen Leiyu Gao yuming Wang State Key Lab of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China

Rock abrasiveness is an important factor affecting the tool's lifetime and efficiency in breaking a *** rock abrasiveness helps in the design,optimization,and mean-life prediction of *** diffraction,cast thin section analysis,and CERCHAR abrasiveness tests were performed on 18 different sandstones to characterize rock abrasiveness and explore new methods for *** relationship between the mineral composition and microstructure of sandstone and abrasiveness was *** results show that different structural maturities have varying effects on *** addition,the higher the structural maturity,the more the ***,in sandstones of the same structural maturity,the abrasiveness increases with equivalent quartz content(EQC).The texture coefficient(TC)and CERCHAR abrasiveness index(CAI)of sandstones with the same structural maturity showed a good linear ***,the correlation coefficients considering the combined parameters are above ***,obtaining the microstructure and mineral composition of sandstone can effectively characterize rock *** also provides a new method for predicting the abrasiveness of the rock in the well.

关键词： Abrasiveness Microstructure Mineral compositions Structural maturity Equivalent quartz content Sandstone

UNIFORMLY VALID ASYMPTOTIC APPROXIMATIONS FOR NONLINEAR SINGULARLY－PERTURBED VECTOR BOUNDARY VALUE PROBLEMS

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Annals of Differential Equations 1996年第3期12卷 326-334页

作者： shi yuming(Qufu Normal University, 273165) Qufu Normal University 273165

In the present paper,we study the uniformly valid asymptotic approximation for thenonlinear singularly-perturbed boundary value problemas ε→ 0+. Unaer some appropriate assumptions, the existence, local uniqueness and theuniformly valid asymptotic approximation of the perturbed solution are shown by employing the diagonalization method.

关键词： diagonalization Valid approximation EMPLOYMENT asymptotic uniqueness

Maternal supplementation with mulberry-leaf flavonoids improves the development of skeletal muscle in the offspring of chickens

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Animal Nutrition 2024年第3期18卷 72-83页

作者： Zhenwu Huang Hongjian Dai Simeng Li Zhe Wang Quanwei Wei Zhonghua Ning yuming Guo Fangxiong shi Zengpeng Lv State Key Laboratory of Animal Nutrition and Feeding College of Animal Science and TechnologyChina Agricultural UniversityBeijing100193China College of Animal Science and Technology Nanjing Agricultural UniversityNanjing210095China State Key Laboratory of Animal Nutrition and Feeding Institute of Animal SciencesChinese Academy of Agricultural SciencesBeijing100193China School of Biotechnology Aksu Vocational and Technical CollegeAksu843000China

The development of skeletal muscle is a crucial factor in determining the meat yield and economic benefits of broiler *** research has shown that mulberry leaves and their extracts can be used to significantly improve the growth performance of livestock and *** present study aims to elucidate the mechanisms involved in the regulation of skeletal muscle development in broiler offspring by dietary mulberry-leaf flavonoids(MLF)supplementation from the perspective of maternal effect theory.A total of 270 Qiling broiler breeder hens were randomly assigned to 3 treatments with different doses of MLF(0,30,60 mg/kg)for 8 weeks before collecting their fertilized *** chicken offspring at 13 and 19 d of embryonic stage,and from 1 to 28 d old after hatching were included in this *** results showed that maternal supplementation increased the breast muscle weight and body weight of the offspring at the embryo and chick stages(P<0.05).This was followed by increased cross-sectional area of pectoral muscle fibres at 14 d(P<0.05).Further determination revealed a tendency towards increased serum levels of insulin-like growth factor 1(IGF-1)(P=0.092)and muscle fibre count(P=0.167)at 1 d post-hatching following maternal MLF treatment,while serum uric acid(UA)was decreased at 14 d after hatching(P<0.05).Moreover,maternal MLF supplementation significantly up-regulated the mRNA expression of the myogenic regulatory factor Myf5 in skeletal muscle at the both embryonic and growth stages(P<0.05).The relative abundance of the downstream protein of BMPR2,Smad1 and p-Smad1/5/9 in the TGFβsignalling pathway was significantly increased by maternal MLF ***,the increased expression of the target protein p-mTOR in the breast muscle of the offspring chicks is in accordance with the improved growth rate of the breast and the *** conclusion,maternal MLF supplementation can promote muscle protein metabolism and muscle fibre development of chick embryos

关键词： Broiler breeder hen Mulberry-leaf flavonoids Offspring Protein metabolism Skeletal muscle

Forecasting supernova observations with the CSST:*** samples

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 164-177页

作者： Chengqi Liu Youhua Xu Xianmin Meng Xin Zhang shi-Yu Li yuming Fu Xiaofeng Wang Shufei Liu Zun Luo Guanghuan Wang Hu Zhan Department of Astronomy School of PhysicsPeking UniversityBeijing 100871China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China Key Laboratory of Space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Beijing Planetarium Beijing Academy of Science and TechnologyBeijing 100044China Leiden Observatory Leiden UniversityNL-2300 RA LeidenThe Netherlands Kapteyn Astronomical Institute University of GroningenNL-9700 AV GroningenThe Netherlands Physics Department Tsinghua UniversityBeijing 100084China School of Astronomy and Space Science University of ChineseAcademy of SciencesBeijing 100049China

The China Space Station Telescope(CSST,also known as Xuntian)is a serviceable two-meter-aperture wide-field telescope operating in the same orbit as the China Space *** CSST plans to survey a sky area of 17,500 deg^(2)of the medium-to-high Galactic latitude to a depth of 25-26 AB mag in at least 6 photometric bands over 255-1,000 *** such a large sky area,slitless spectra will also be taken over the same wavelength range as the imaging *** though the CSST survey is not dedicated to time-domain studies,it would still detect a large number of transients,such as supernovae(SNe).In this paper,we simulate photometric SN observations based on a strawman survey plan using the Sncosmo *** its 10-year survey,the CSST is expected to observe about 5 million SNe of various *** quality cuts,we obtain a“gold”sample that comprises roughly 7,400 SNe Ia,2,200 SNe Ibc,and 6,500 SNeⅡcandidates with correctly classified percentages reaching 91%,63%,and 93%(formally defined as classification precision),*** same survey can also trigger alerts for the detection of about 15,500 SNe Ia(precision 61%)and 2,100 SNeⅡ(precision 49%)candidates at least two days before the light ***,the near-ultraviolet observations of the CSST will be able to catch hundreds of shock-cooling events serendipitously every *** results demonstrate that the CSST can make a potentially significant contribution to SN studies.

关键词： space-based ultraviolet optical and infrared telescopes supernovae data analysis