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Asymptotic Behavior in a Quasilinear Fully Parabolic Chemotaxis System with Indirect Signal Production and Logistic Source

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Journal of Partial Differential Equations 2021年第2期34卷 129-143页

作者： li Dan li zhongping College of Mathematic and Information China West Normal UniversityNanchong 637009China

In this paper,we study the asymptotic behavior of solutions to a quasilinear fully parabolic chemotaxis system with indirect signal production and logistic source{ut=■·(D(u)■u)-■·(S(u)■v)+b-μur,x∈Ω,t>0,vt=Δv+a1v+b1w,x∈Ω,t>0,wt=Δw-a2w+b2u,x∈Ω,t>0 under homogeneous Neumann boundary conditions in a smooth bounded domainΩ■R^(N)(N≥1),where b≥0,γ≥1,ai≥1,μ,bi>0(i=1,2,D,S∈C^(2)([0,∞))fulfilling D(S)≥a0(s+1)^(-a),0≤S(s)≤b0(s+1)^(β)for all s≥0,where a0,b0>0 and a,β≤R are *** pur purpose of this paper is to prove that if b≥0 andμ>0 sufficiently large,the globally bounded solution(u,v,w)with nonnegative initial data(u0,v0,w0)satisfies||u(·,t)-(b/μ)^(1/γ)L∞(Ω)+||V(·,t)+b1b2/a1a2(b/μ)^(1/γ)||L∞(Ω)+||w(·,t)+b2/a2(b/μ)^(1/γ)||L∞(Ω)→0ast→∞.

关键词： Chemotaxis system indirect signal logistic source asymptotic behavior

RELAXED CONDITIONS FOR CONSENSUS IN MULTI-AGENT COORDINATION

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Journal of Systems Science & Complexity 2008年第3期21卷 347-361页

作者： Qin li zhongping JIANG Department of Electrical and Computer Engineering Polytechnic University Six Metrotech Center Brooklyn NY 11201 USA

This paper proposes relaxed sufficient conditions for the consensus of multi-agent systems by the averaging protocols with time-varying system topology. Bidirectional information exchange between neighboring agents is considered and both the discrete-time and continuous-time consensus protocols are studied. It is shown that the consensus is reached if there exists an unbounded time sequence such that two agents who own the maximum and minimum states at each time instant in the sequence will be jointly connected at some future time. Further, this result is applied to the original nonlinear Vicsek model, and a sufficient condition for the heading consensus of the group with restricted initial conditions is obtained.

关键词： Averaging protocol consensus multi-agent systems Vicsek's model

General Trends in Electronic Structure, Stability, Chemical Bonding and Mechanical Properties of Ultrahigh Temperature Ceramics TMB_2(TM=transition metal)

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Journal of Materials Science & Technology 2015年第3期31卷 285-294页

作者： Yanchun Zhou Huimin Xiang Zhihai Feng zhongping li Science and Technology on Advance Functional Composite Laboratory Aerospace Research Institute of Materials & Processing Technology

The electronic structure, stability, chemical bonding and mechanical properties of 3d, 4d and 5d transition metal diboride TMB2 were investigated using first-principles calculations based on density functional theory. All the primary chemical bonds, i.e., metallic, ionic and covalent have contributions to the bonding of TMB2. The number of valence electrons of transition metals or the valence electron concentration(VEC) of TMB2 has strong effects on the lattice parameters, stability and mechanical properties of TMB2. Both lattice constants a and c decrease with VEC, but c decreases faster than a, which is attributed to the enhanced TM de B p(sp2) bonding. Bulk modulus B of TMB2 increases continuously with VEC due to the enhanced TM de B p(sp2) and TM dd bonding. Shear modulus G increases with VEC,reaching a maximum at VEC=3.33, and then decreases with further increase of VEC. YB2 and Mn B2 have low Young’s modulus and are predicted to have good thermal shock resistance. According to Pugh’s criterion(G/B < 0.571), Mn B2, Mo B2 and WB2are predicted as ductile or damage tolerant ultrahigh temperature ceramics(UHTCs).

关键词： Ultrahigh temperature ceramics Transition metal di

Blow-Up and Boundedness in Quasilinear Parabolic-Elliptic Chemotaxis System with Nonlinear Signal Production

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Journal of Partial Differential Equations 2023年第3期36卷 262-285页

作者： CAO Ruxi li zhongping College of Mathematics and Information China West Normal UniversityNanchong 637009China.

In this paper,we consider the quasilinear chemotaxis system of parabolicelliptic type■.under homogeneous Neumann boundary conditions in a smooth bounded domain■n≥*** nonlinear diffusivity D(ζ)and chemosensitivity f(ζ)as well as nonlinear signal production g(ζ)are supposed to extend the prototypes■We proved that if m+k+l>1+2/n,then there exists nonnegative radially symmetric initial data uo such that the corresponding solutions blow up in finite ***,the system admits a global bounded classical solution for arbitrary initial datum when m+k+l<1+2/n.

关键词： Chemotaxis nonlinear diffusion blow-up boundedness nonlinear signal production

The preparation and application of microbubble contrast agent combining ultrasound imaging and magnetic resonance imaging

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Chinese Science Bulletin 2009年第17期54卷 2934-2939页

作者： YANG Fang li YiXin CHEN zhongping GU Ning State Key Laboratory of Bioelectronics Jiangsu Laboratory for Biomaterials and Devices School of Biological Science and MedicalEngineering Southeast University Nanjing 210096 China

Encapsulated gas microbubbles are well known as ultrasound contrast agents (UCAs) for medical ultrasound (US) imaging. With the development of shell materials and preparation technologies, the application of microbubbles has been enormously popular in molecular imaging, drug delivery and targeted therapy, etc. The objective of this study is to develop Fe3O4 nanoparticle-inclusion microbubble construct. The in vitro US imaging experiment indicates that the Fe3O4 nanoparticle-inclusion microbubbles have higher US enhancement than those without Fe3O4 nanoparticle-inclusion. According to the microbubble dynamic theory, the acoustic scattering properties can be quantified by scattering cross-section of the shell. The scattering study on Fe3O4 nanoparticle-inclusion microbubbles of different concentration shows that within a certain range of concentration, the scattering cross-section of microbubble increases with the addition of Fe3O4 nanoparticles. When exceeding the concentration range, the ultrasonic characteristic of microbubbles is damped. On the other hand, since Fe3O4 nanoparticles can also serve as the Magnetic Resonance Imaging (MRI) contrast agent, they can be potentially used as contrast agents for the double-modality (MRI and US) clinical studies. However, it is important to control the concentration of Fe3O4 nanoparticles in the shell in order to realize the combined functions of US and MRI.

关键词： Fe3O4纳米粒子超声造影剂浓度范围外壳材料分子成像散射截面动力学理论声散射特性

Composition and Evolution of Hydrogen Isotopes of n-Akanes Generated from Anhydrous Pyrolysis of Sediments from Lake Gahai,Gannan,China

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Acta Geologica Sinica(English Edition) 2021年第5期95卷 1725-1735页

作者： DUAN Yi WU Yingzhong XING Lantian li zhongping ZHANG Ting Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences and Gansu Provincial Key Laboratory of Petroleum ResourcesLanzhou 730000China School of Earth Science&Resources Chang’an UniversityXi’an 710054China Shaanxi Center of Mineral Geological Survey Xi'an 710068China

To understand the thermal evolution of lacustrine sedimentary n-alkane hydrogen isotopic composition(δD),especially bacterially derived n-alkanes,anhydrous thermal simulation experiments were performed with sediments from Lake Gahai(Gannan,China).We analyzed the original and pyrolysis-generated n-alkanes and theirδD *** results showed that thermal maturity and n-alkane origins significantly affected the distribution of pyrolysis-generated *** immature to post-mature sediments,the bacterial-derived medium-chain n-alkanes generally had depletedδD *** maximum difference in averageδD values between the bacterial-and herbaceous plant-derived medium-chain n-alkanes was 32‰,and the maximum difference in δD values among individual n-alkanes was 59‰.We found that the averageδD value of pyrolysis-generated n-alkanes from different latitude was significantly different in immature to highly mature sediments,but similar in post-mature *** hydrogen isotopes of sedimentary n-alkanes can be used as indicators for paleoclimate/paleo-environment conditions only when sediments are immature to highly *** thermal evolution,the δD value of generated individual n-alkanes and the averageδD value increased with thermal maturity,indicating that hydrogen isotopes of sedimentary n-alkanes can be used as an index of organic matter *** established mathematical models of average δD values of generated n-alkanes from immature to post-mature sediments using n C_(21)^(-)/nC_(21)^(+)and average chain *** results improve our understanding of the distribution andδD value of sedimentary n-alkanes derived from herbaceous plants in mid-latitude plateau cold regions.

关键词： freshwater lake sediment n-alkane simulation experiment bacterial origin hydrogen isotope thermal evolution

Theoretical prediction on mechanical and thermal properties of a promising thermal barrier material:Y_(4)Al_(2)O_(9)

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Journal of Advanced Ceramics 2015年第2期4卷 83-93页

作者： Yanchun ZHOU Huimin XIANG Xinpo LU Zhihai FENG zhongping li Science and Technology of Advanced Functional Composite Laboratory Aerospace Research Institute of Materials and Processing TechnologyNo.1 South Dahongmen RoadBeijing 100076China

The mechanical and thermal properties of Y_(4)Al_(2)O_(9)were predicted using a combination of first-principles and chemical bond theory(CBT)*** functional theory(DFT)computations were performed for the structural,mechanical,and thermal properties,and the results were confirmed by chemical bond *** on the calculated equilibrium crystal structure,heterogeneous bonding nature has been revealed,i.e.,Al-O bonds are stronger than Y-O *** second-order elastic constants c44,c55,and c66 demonstrate the low shear deformation *** G/B ratio suggests that Y_(4)Al_(2)O_(9)is a damage tolerant ceramic.Y_(4)Al_(2)O_(9)shows anisotropy in elastic behavior based on the discussion of direction dependence of Young’s *** hardness is predicted to be 10.2 GPa from calculated elastic *** thermal expansion coefficient(TEC)calculated by chemical bond theory is 7.51×10^(-6)K^(-1).In addition,the minimum thermal conductivity of Y_(4)Al_(2)O_(9)is estimated to be 1.13 W·m^(-1)·K^(-1),and the thermal conductivity decreases with temperature as 1305.6/T.

关键词： Y4Al2O9 chemical bonding elastic constants thermal conductivity thermal expansion coefficient(TEC)

Ordering policies and coordination in a twoechelon supply chain with Nash bargaining fairness concerns

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Journal of Management Analytics 2017年第1期4卷 55-79页

作者： Caimin Wei zhongping li Zongbao Zou Department of Mathematics Shantou UniversityShantou 515063People’s Republic of China Guangdong Provincial Key Lab of Digital Signals and Image Processing Shantou UniversityShantou 515063People’s Republic of China Sun Yat-Sen Business School Sun Yat-sen UniversityGuangzhou 510275People’s Republic of China

This paper investigates the ordering policies of two competitive retailers,and the coordination status of a two-echelon supply chain by considering the fairness concerns of channel *** consider that two retailers compete with each other over price,where overstock and shortage are *** assume that the demand is stochastic and considered with additive ***,based on the Nash bargaining fairness reference point,we obtain the optimal decisions of the fairness-concerned channel members in both the centralized and the decentralized cases using a two-stage game ***,we analyze the coordination status of the supply chain with Nash bargaining fairness concerns using ideas of ***,numerical experiments are used to illustrate the influence of some parameters,the fairness-concerned behavioral preference of the channel members on the optimal decisions and the coordination status of supply *** managerial insights are obtained.

关键词： supply chain Nash bargaining fairness concern sale price coordination

Mid—Late Neoproterozoic rift-related volcanic rocks in China:Geological records of rifting and break-up of Rodinia

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Geoscience Frontiers 2012年第4期3卷 375-399页

作者： linqi Xia Zuchun Xia Xueyi Xu Xiangmin li zhongping Ma Xi＇an Institute of Geology and Mineral Resources China Geological Survey Xi＇an Shaanxi 710054 China

Early Cambrian and Mid--Late Neoproterozoic volcanic rocks in China are widespread on several Precambrian continental blocks, which had aggregated to form part of the Rodinia supercon- tinent by ca. 900 Ma. On the basis of petrogeochemical data, the basic lavas can be classified into two major magma types： HT （Ti/Y 〉 500） and LT （Ti/Y 〈 500） that can be further divided into HT1 （Nb/La 〉 0.85） and HT2 （Nb/La ≤ 0.85）, and LT1 （Nb/La 〉 0.85） and LT2 （Nb/La ≤ 0.85） subtypes, respectively. The geochemical variation of the HT2 and LT2 lavas can be accounted for by lithospheric contamination of asthenosphere- （or plume-） derived magmas, whereas the parental magmas of the HT1 and LT1 lavas did not undergo, during their ascent, pronounced lithospheric contamination. These volcanics exhibit at least three characteristics：（1） most have a compositional bimodality; （2） they were formed in an intracontinental rift setting; and （3） they are genetically linked with mantle plumes or a mantle surperplume. This rift-related volcanism at end of the Mid-- Neoproterozoic and Early Cambrian coincided temporally with the separation between Australia-- East Antarctica, South China and Laurentia and between Australia and Tarim, respectively.

关键词： Neoproterozoic Bimodal volcanism Continental rift Mantle plume Rodinia supercontinent China