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Journal of Computational Mathematics 2022年第2期40卷 258-274页

作者： libin liu Yanping Chen Ying Liang School of Mathematics and Statistics Nanning Normal UniversityNanning 530023China School of Mathematical Sciences South China Normal UniversityGuangzhou 510631China

In this paper,we study a nonlinear first-order singularly perturbed Volterra integro-differential equation with *** equation is discretized by the backward Euler for differential part and the composite numerical quadrature formula for integral part for which both an a priori and an a posteriori error analysis in the maximum norm are *** on the a priori error bound and mesh equidistribution principle,we prove that there exists a mesh gives optimal first order convergence which is robust with respect to the perturbation *** a posteriori error bound is used to choose a suitable monitor function and design a corresponding adaptive grid generation ***,we extend our presented adaptive grid algorithm to a class of second-order nonlinear singularly perturbed delay differential *** results are provided to demonstrate the effectiveness of our presented monitor ***,it is shown that the standard arc-length monitor function is unsuitable for this type of singularly perturbed delay differential equations with a turning point.

关键词： Delay Volterra integro-differential equation Singularly perturbed Error analysis Monitor function

Low net primary productivity of dominant tree species in a karst forest, southwestern China： first evidences from tree ring width and girth increment

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Acta Geochimica 2017年第3期36卷 482-485页

作者： Jian Ni Haiyang Xu libin liu College of Chemistry and Life Sciences Zhejiang Normal University Yingbin Avenue 688 Jinhua 321004 China State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of SciencesLincheng West Road 99 Guiyang 550081 China Puding Karst Ecosystem Research Station Chinese Academy of Sciences Puding 562100 China

Aboveground net primary productivity(ANPP)of two dominant species, one deciduous tree(Platycarya strobilacea) and one evergreen tree(Machilus cavaleriei),was estimated based on the tree-ring width and the girth increment as well as allometric functions in a karst evergreen and deciduous broadleaved mixed forest in central Guizhou Province, southwestern China. Results showed that the ANPP increased from 1961 to 2015, especially during the last 20–30 years, but with strong variations. The deciduous tree had higher ANPP than the evergreen tree according to two kinds of estimates by the tree ring and girth increment. The averaged ANPP for these two mature trees was 2.27 kg/individual/year, ca. 8 t/ha/year considering the normal stand density. Such karst forest productivity was lower than the natural subtropical forests in China and in the world.

关键词： Biomass increment Tree ring Girth measurement Karst evergreen and deciduous broadleaved forest Allometric functions

Grafting of 4-Vinyl Pyridine onto Nylon-6 Initiated by Redox System

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Chinese Journal of Chemistry 2011年第2期29卷 351-355页

作者： Zhou Jian Bai libin Qin Hong liu Yinghai College of Chemistry and Environmental Science Hebei University Baoding Hebei 071002 China

The graft copolymerization of 4-vinyl pyridine （4VP） onto nylon-6 （PA6） was studied by using potassium diperiodatonickelate（IV）（DPN）-PA6 redox system in alkaline medium. The structures of graft copolymers were confirmed by Fourier transfer infrared spectroscopy （FTIR） and X-ray diffraction. The properties of graft copolymers were investigated by thermogravimetric analysis （TGA）. A mechanism was proposed to explain the generation of radicals and the initiation. The effects of reaction variables, such as the initiator concentration, the ratio of 4VP to PA6, pH as well as reaction temperature and time were investigated. Graft copolymers with high grafting efficiency （〉95%） were obtained, which indicated that DPN-PA6 redox system is an efficient initiator for this graft copolymerization. The quaternized PA6-g-P4VP （QPAVP） was proved to be an excellent adsorbent to heavy metal ions.

关键词： potassium diperiodatonickelate(IV) nylon-6 4-vinyl pyridine graft copolymerization redox initiation,adsorption

Quantification of selected monohydroxy metabolites of polycyclic aromatic hydrocarbons in human urine

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Science China Chemistry 2015年第10期58卷 1579-1584页

作者： libin liu Yueping Luo Junping Bi Haifang Li Jin-Ming Lin Key Laboratory of Monitoring for Heavy Metal Pollutants Hunan Province Environmental Monitoring Centre Beijing Key Laboratory of Microanalytical Methods and Instrumentation Department of Chemistry Tsinghua University

An analytical method was developed to quantitatively determine selected monohydroxy metabolites of polycyclic aromatic hydrocarbons(PAHs) in human urine. The procedure included enzymatic hydrolysis to cleave the conjugated metabolites, solid-phase microextraction enrichment, and gas chromatography-mass spectrometry analysis. The method proved to be sensitive enough to detect the selected PAH metabolites in human urine.

关键词： polycyclic aromatic hydrocarbons metabolites human urine solid-phase microextraction GC/MS

Nanoscale triple-gate FinFET design considerations based on an analytical model of short-channel effects

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Science China(Information Sciences) 2014年第4期57卷 228-234页

作者： XIE Qian LIANG RenRong WANG Jing liu libin XU Jun Tsinghua National Laboratory for Information Science and Technology Institute of MicroelectronicsTsinghua University

In this paper,a three-dimensional(3-D)analytical model for short-channel effects(SCEs)in a nanoscale triple-gate(TG)FinFET is derived based on solving a boundary value problem using the 3-D Poisson’s *** model is validated using 3-D numerical simulations(TCAD Sentaurus).Results show that SCEs in a TG FinFET can be controlled by reducing either the fin thickness(D)or height(H).On the other hand,when fixing the drive capability of turn-on current,*** the total width of the conductive channel,and changing the ratio of D and H,there exists a case where SCEs are worst,and SCEs can be reduced by either increasing or decreasing the ratio from the worst *** SCEs model can be used to predict the minimum channel length(Lmin)of a device when D,H,and tox are fixed,while keeping SCEs at a tolerable *** on the analytical model,the insights into the physics of SCEs in nanoscale TG FinFET are discussed,and design considerations are investigated.

关键词： triple-gate FinFET short-channel effects(SCEs) scale length design considerations modeling

Zr-xNb-4Sn alloys with low Young's modulus and magnetic susceptibility for biomedical implants

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Progress in Natural Science:Materials International 2021年第5期31卷 772-778页

作者： Renhao Xue Dong Wang Yueyan Tian Jiang Wang libin liu Ligang Zhang School of Material Science and Engineering Central South University Guangxi Key Laboratory of Information Materials Guilin University of Electronic Technology State Key Laboratory of Powder Metallurgy Central South University

The microstructure,mechanical and magnetic properties of Zr-x(8,9,10,wt.%)Nb-4 Sn alloys were investigated to obtain novel Zr-based alloy with low Young’s modulus and magnetic susceptibility for biomedical *** homogenization annealing,hot forging and solution annealing,Zr-8 Nb-4 Sn,Zr-9 Nb-4 Sn and Zr-10 Nb-4 Sn alloys were composed of β+α" phase,β+α" phase,β+ω phase,*** temperature at which the α" and ωphase were transformed into β phase during the heating process was about 200 ℃ and the phase transformation temperature decreased with the increase of Nb *** all the Zr-x(x=8,9,10)Nb-4 Sn(wt.%) alloys,Zr-9 Nb-4 Sn alloy had the lowest Young’s modulus of 46.6 GPa and the low magnetic susceptibility of1.294×10-6cm~3 g-1,which has a good application prospect for biomedical applications.

关键词： Zirconium-based alloys Microstructure Mechanical properties Phase transformation Biomedical materials

Low carbon storage of woody debris in a karst forest in southwestern China

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Acta Geochimica 2019年第4期38卷 576-586页

作者： Yangyang Wu libin liu Chunzi Guo Zhonghua Zhang Gang Hu Jian Ni State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of SciencesLincheng West Road 99Guiyang 550081China University of Chinese Academy of Sciences Yuquan Road 19ABeijing 100049China Puding Karst Ecosystem Research Station Chinese Academy of SciencesPudingAnshun 562100China College of Chemistry and Life Sciences Zhejiang Normal UniversityYingbin Avenue 68& Jinhua 321004China Haihe River Water Resources Protection Bureau Haihe River Water Conservancy CommissionThe Ministry of Water Resources of the People's Republic of ChinaLongtan Road 15Tianjin 300170China School of Enviroment and Life Science Guangxi Teachers Education UniversityMingxiu East Road 175Nanning 530001China Key Laboratory of Environment Change and Resources Use in Beibu Gulf Ministry of EducationMingxiu East Road 175Nanning 530001China

The properties of woody debris(WD) vary across different forests under various soil *** to the relatively shallow and low amounts of soils on karst terrains, it is necessary to determine the WD carbon inventory of karst forests. In this study, we recorded WD with a basal diameter for standing snags and the largeend diameter for fallen logs of ≥ 1 cm. The carbon density of WD in a secondary karst mixed evergreen and deciduous broad-leaved forest that had been clear-cut 55 years ago in southwestern China were inventoried in a 2 ha plot. Woody debris carbon density calculated using specific gravity and carbon concentration was 4.07 Mg C ha^-1. Woody debris with diameters ≥ 10 cm(coarse WD) constituted 53.8% of total carbon storage whereas WD < 10 cm in diameters(fine WD) accounted for more pieces of WD(89.9%).Lithocarpus confinis contributed the most WD carbon(26.5%). Intermediate decayed WD was relatively more abundant, but WD with final decay contributed the least to the total pieces of WD(6.7%). The contribution of WD to carbon storage of karst forest was low compared to other forests worldwide. Significant positive correlations were found between WD carbon and biodiversity(R^2= 0.035,p < 0.01) and elevation(R^2= 0.047, p < 0.01) and negative correlations was found in outcrop coverage(R^2= 0.034, p <0.01). Further studies are needed to elucidate the ecological functions of WD to better understand their roles in maintaining biodiversity, enhancing productivity, and controlling vegetation degradation in karst forest ecosystems.

关键词： Secondary forest Fine woody debris Coarse woody debris Dead wood Karst Subtropical China

Designing high-strength titanium alloy using pseudo-spinodal mechanism through diffusion multiple experiment and CALPHAD calculation

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Journal of Materials Science & Technology 2021年第15期74卷 78-88页

作者： Di Wu libin liu Lijun Zeng Wenguang Zhu Wanlin Wang Xiaoyong Zhang Junfeng Hou Baoliang liu Jiafeng Lei Kechao Zhou State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China School of Material Science and Engineering Central South UniversityChangsha 410083China School of Metallurgy and Environment Central South UniversityChangsha 410083China School of Metallurgical Engineering Xi'an University of Architecture and TechnologyXi'an 710055China School of Materials Science&Engineering North Minzu UniversityYinchuan 750021China Xi'an Trianlge Defence Incorporated Company Xi'an710089China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

This study used the pseudo-spinodal mechanism to obtain the ultrafineαphase for designing highstrength titanium *** multiple experiments were designed to find the composition range of TM-x Mo-y V alloy(TM:Ti-4.5 Al-2 Cr-2.5 Nb-2 Zr-1 Sn)for obtaining ultrafineα*** results confirm that when the alloy composition is located near the intersection of theαandβphase free energy curves,the alloy will undergo pseudo-spinodal transformation and obtain the ultrafineα*** designed TM-6 Mo-3 V alloy has a yield strength of 1411 MPa and an elongation of 6.5%.The strength of the alloy depends on the thickness,fraction of theαphase and the solid solution strengthening effect of the alloying *** deformation mechanism of the alloy is the dislocation slip of theαandβphases and the twin deformation of theα*** large number ofα/βinterfaces produced by the fineαphase is the main reason for limiting the ductility of the *** use of the pseudo-spinodal mechanism combined with diffusion multiple experiments and CALPHAD is an effective method for designing high-strength titanium alloys.

关键词： Pseudo-spinodal mechanism Alloy design CALPHAD Diffusion multiple Strengthening mechanism

Nonlinear characteristics analyses of particle motion for predicting flow regimes

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Particuology 2020年第6期18卷 134-141页

作者： Panxing Kang Yujian Lu Lei Yang libin liu Xiayi(Eric)Hu Xiao Luo Hongbo Chen Yefeng Zhou Rui Zhang National and Local United Engineering Research Centre for Chemical Process Simulation and Intensification Chemical Process Simulation and Optimization Engineering Research Center of the Ministry of EducationXiangtan UniversityXiangtan 411105China College of Chemistry and Chemical Engineering Hunan UniversityChangsha 410082China

Gas-solid flow regimes have a significant impact on particle transport and separation in a fluidized bed *** this study,to determine flow regime transitions in gas-solid fluidized beds,an acoustic technique was used to detect and analyze the behavior of gas and *** complexity,fluctuation complexity,and Shannon entropy analyses of acoustic emission signals were performed to examine non linear system characteristics,and to determine the flow regime transiti on velocities uc,uk,and ufd-Moreover,using the standard deviation of pressure signals,pressure measurements and acoustic measurements were *** relative deviations(RDs)between the experimental and empirical values of uk were 8.8%,13.7%,8.8%,and 30.4%for the algorithm complexity,fluctuation complexity,Shannon entropy,and pressure signal standard deviation,respectively,while the respective RDs for Ufd were 15.7%,23.9%,15.7%,and 97.8%.The RDs between the experimental and empirical values of uc were all 6.4%.The experimental values obtained from acoustic signal measurements were therefore closer to the empirical *** summary,the integration of non-intrusive acoustic measurements,complexity analysis,and Shannon entropy analysis is suitable for identifying flow regime transitions.

关键词： Acoustic emission Nonlinear characteristics Complexity analysis Shannon entropy Flow regime transition

Thermodynamic database of multi-component Mg alloys and its application to solidification and heat treatment

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Journal of Magnesium and Alloys 2016年第4期4卷 249-264页

作者： Guanglong Xu Ligang Zhang libin liu Yong Du Fan Zhang Kai Xu Shuhong liu Mingyue Tan Zhanpeng Jin School of Materials Science and Engineering Central South UniversityChangsha 410083China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

An overview about one thermodynamic database of multi-component Mg alloys is given in this *** thermodynamic database includes thermodynamic descriptions for 145 binary systems and 48 ternary systems in 23-component(Mg–Ag–Al–Ca–Ce–Cu–Fe–Gd–K–La–Li–Mn–Na–Nd–Ni–Pr–Si–Sn–Sr–Th–Y–Zn–Zr)***,the major computational and experimental tools to establish the thermodynamic database of Mg alloys are briefly ***,among the investigated binary and ternary systems,representative binary and ternary systems are shown to demonstrate the major feature of the ***,application of the thermodynamic database to solidification simulation and selection of heat treatment schedule is described.

关键词： Thermodynamic database Phase diagram Mg alloys Solidification Heat treatment