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Dramatic impact of metric choice on biogeographical regionalization

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Plant Diversity 2020年第2期42卷 67-73页

作者： Jian-fei Ye Yun Liu zhi-Duan Chen State Key Laboratory of Systematic and Evolutionary Botany Institute of BotanyChinese Academy of SciencesBeijing 100093China University of Chinese Academy of Sciences Beijing 100049China Beijing Botanical Garden.Institute of Botany Chinese Academy of SciencesBeijing W0093China

For a quantitative biogeographical regionalization,the choice of an appropriate dissimilarity index to measure pairwise distances is *** different metrics have been used,but there is no specific study to test the impact of metric choice on biogeographical *** herein applied a hierarchical cluster analysis on the mean nearest taxon distance(MNTD)and the phylogenetic turnover component of the SФrensen dissimilarity index(pβsim)pairwise distances to generate two schemes of phylogenetic regio nalization of the Chinese flora,and then evaluated the effect of metric *** regionalization based on MNTD was influenced by richness differences,but regionalization based on pβsim can clearly reflect the evolutionary history of the Chinese *** provided a brief description of the five regions identified by pβsim,and the regionalization can help develop strategies to effectively conserve the taxa and floristic regions with different origins and evolutionary histories.

关键词： Angiosperms Chinese flora Dissimilarity index Distance metrics Spatial turnover

Stabilization of Cu/ZnO Based Catalysts by Nickel Additive in Methanol Decomposition

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Chemical Research in Chinese Universities 2001年第4期17卷 420-425页

作者： XI Jing-yu WANG zhi-fei LU Gong-xuan State Key Laboratory for Oxo Synthesis and Selective Oxidation Lanzhou Institute of Chemical PhysicsThe Chinese Academy of SciencesLanzhou 730000P.R.China

A series of Cu/Zn based catalysts with and without Ni, prepared by the co-precipitation method, has been studied for methanol decomposition. CO and H2 are the major products. The Cu/Zn catalysts show a low initial activity and a poor stability. The formation of the CuZn alloys was observed in the deactivated Cu/Zn catalysts which were used for methanol decomposition at 250 . When small amounts of Ni were added in the catalyst, the Cu/Zn/Ni(molar ratio 5/4/ x) catalysts showed a high activity at a low temperature. The activity and the stability of the catalyst depend on the nickel content. The activity of the Cu/Zn/Ni catalysts was maintained at a. relatively stable value of 78% conversion of methanol with 95% selectivity of H2, 93% selectivity of CO, and a more than 70% yield of hydrogen was obtained at 250 C when x >1. The stability of the Cu/Zn/Ni (molar ratio 5/4/x) catalysts showed the maximum (ca 88%) when x=1. The stabilization effect of nickel on the Cu/Zn based catalysts may lead to the increasing of the dispersion of active Cu species and the prevention of CuZn alloys formation.

关键词： Nickel Cu/Zn catalysts Stabilization Methanol Decomposition

One-pot scalable in situ growth of highly corrosion-resistant MgAl-LDH/MBT composite coating on magnesium alloy under mild conditions

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Journal of Materials Science & Technology 2021年第33期92卷 225-235页

作者： Ting Hu Yuejun Ouyang zhi-Hui xie Liang Wu Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province College of Chemistry and Chemical EngineeringChina West Normal UniversityNanchong 637002China Hunan Engineering Laboratory for Preparation Technology of Polyvinyl Alcohol(PVA)Fiber Material Huaihua UniversityHuaihua 418000China College of Materials Science and Engineering/National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China

Current corrosion-resistant layered double hydroxide(LDH)coating on Mg alloy is usually in situ grown in autoclave by hydrothermal methods under high temperature and high-pressure conditions,which is unfavorable for industrial *** report that an inhibitor(2-mercaptobenzothiazole,MBT)incorporated composite(Mg Al-LDH/MBT)coating can be in situ deposited on bare AZ31 Mg alloy surface with the assistance of a chelating agent(ethylenediaminetetraacetic acid)under a relatively low temperature(95℃)and ambient pressure by a one-pot *** successful formation of LDH/MBT composite coating is confirmed by a series of characterizations,such as X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and energy dispersive spectroscopy(EDS).The corrosion resistance of the composite coating is evaluated by means of hydrogen evolution measurement,electrochemical impedance spectroscopy(EIS),Tafel polarization curves,and neutral salt spray *** tests show that the LDH/MBT composite coating has a very low corrosion current density(1.7310^(-8)A cm^(-2)),an extremely high charge transfer resistance(2.336 M cm^(2)),and does not show any corrosion pits even after 15 d of exposure to a Na Cl solution or 7 d of exposure to salt fog environment,manifesting the good and robust corrosion ***,the deposition and corrosion protection mechanisms of the Mg Al-LDH/MBT composite coating are also discussed and proposed based on the EDS characterization of the coating after long-time exposure.

关键词： Magnesium alloy Coating Corrosion resistance Layered double hydroxide

Protein sequence analysis based on hydropathy profile of amino acids

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2012年第2期13卷 152-158页

作者： Xiao-li xie Li-fei ZHENG Ying YU Li-ping LIANG Man-cai GUO John SONG zhi-fa YUAN College of Sciences Northwest A&F UniversityYangling 712100China College of Animal Science and Technology Northwest A&F University Yangling 712100 China College of Animal Science and Technology China Agriculture UniversityBeijing 100193China Department of Animal and Avian Sciences University of MarylandCollege ParkMD 20742USA

Biology sequence comparison is a fundamental task in computational *** to the hydropathy profile of amino acids,a protein sequence is taken as a string with three *** curves of the new protein sequence were defined to describe the protein sequence.A new method to analyze the similarity/dissimilarity of protein sequence was proposed based on the conditional probability of the protein ***,the protein sequences of ND6(NADH dehydrogenase subunit 6)protein of eight species were taken as an example to illustrate the new *** results demonstrated that the method is convenient and efficient.

关键词： Protein sequence Sequence comparison Similarity/dissimilarity Conditional probability

The Low-Rank Approximation of Fourth-Order Partial-Symmetric and Conjugate Partial-Symmetric Tensor

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Journal of the Operations Research Society of China 2023年第4期11卷 735-758页

作者： Amina Sabir Peng-fei Huang Qing-zhi Yang School of Mathematics and Statistics Kashi UniversityKashi844008XinjiangChina School of Mathematical Sciences and LPMC Nankai UniversityTianjin300071China

We present an orthogonal matrix outer product decomposition for the fourth-order conjugate partial-symmetric(CPS)tensor and show that the greedy successive rank-one approximation(SROA)algorithm can recover this decomposition *** on this matrix decomposition,the CP rank of CPS tensor can be bounded by the matrix rank,which can be applied to low-rank tensor ***,we give the rank-one equivalence property for the CPS tensor based on the SVD of matrix,which can be applied to the rank-one approximation for CPS tensors.

关键词： Conjugate partial-symmetric tensor Approximation algorithm Rank-one equivalence property Convex relaxation

Matrix test measurements of ground-borne vibration induced by the heavy-duty trains on embankment and cutting tracks in a loess area

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Earthquake Engineering and Engineering Vibration 2021年第3期20卷 605-620页

作者： xie Qiang Wu zhi-Hui Dong Jie Zhong Shuai School of Civil Engineering Chongqing UniversityChongqing 400045China College of Civil Engineering Hebei University of ArchitectureZhangjiakou 075000China

This paper presents a comparative analysis of ground vibration in three directions generated by a heavy-duty railway with various track *** vibration characteristics in the plane area were investigated by using matrix test *** peak attenuation was faster within 25 m from the embankment,and the high-frequency vibration attenuates faster with increased *** the cutting section with multi-stage soil slope,decay rate of acceleration was relatively *** acceleration level of the plane region ranged to 82.2-89.1 dB by the single C80 *** the acceleration level caused by the C80 trains running parallel after meeting showed a distinct *** increment of the cutting section was much larger compared with the embankment section,with the increment ranging from 1.2-2.5 *** terms of the cutting section,Y direction acceleration was dominant closer to the *** 10-30 m of the track,the Y direction acceleration(perpendicular to the rail)decreased rapidly and became comparable to the X direction(parallel to the rail)and Z ***,the cutting case generated a higher level of vibration in all three directions compared to the embankment,but as the distance from track increased,the deviation between acceleration gradually decreased.

关键词： heavy-duty railway different track sections field measurement vibration response characteristics cutting slope

Existence of Positive Solutions to a Fractional-Kirchhoff System

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 225-240页

作者： Peng-fei Li Jun-hui xie Dan Mu School of Mathematics and Statistics Hubei Minzu UniversityEnshi445000China

LetΩbe a bounded smooth domain in RN(N≥3).Assuming that 00 are constants,we consider the existence results for positive solutions of a class of fractional elliptic system below,{(a+b[u]^(2)_(s))(-Δ)^(s)u=vp+h_(1)(x,u,v,▽u,▽v),x∈Ω,(-Δ)^(s)v=u^(q)+h_(2)(x,u,▽,▽u,▽v),x∈Q,u,v>0,x∈Ω,u=v=0,x∈RN\Ω.Under some assumptions of hi(x,u,v,▽u,▽v)(i=1,2),we get a priori bounds of the positive solutions to the problem(1.1)by the blow-up methods and rescaling *** on these estimates and degree theory,we establish the existence of positive solutions to problem(1.1).

关键词： fractional-Kirchhoff system a priori bounds degree theory positive solution

Suspension calcination and alkali leaching of low-grade high-sulfur bauxite:Desulfurization, mineralogical evolution and desilication

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International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 602-610页

作者： Hong-fei Wu Jun-qi Li Chao-yi Chen fei-long Xia Zhen-shan xie Department of Metallurgical Engineering College of Materials and MetallurgyGuizhou UniversityGuiyang 550025China Guizhou Province Key Laboratory of Metallurgical Engineering and Process Energy Saving Guiyang 550025China

To enable the utilization of low-grade and high-sulfur bauxite, the suspension calcination was used to remove the sulfur and the activate silica minerals, and the calcinated bauxite was subjected to a desilication process in Na OH solution under atmospheric pressure. The desulfurization and desilication properties and mineralogical evolution were studied by X-ray diffraction, thermogravimetry–differential thermal analysis, scanning electron microscopy, and FactSage methods. The results demonstrate that the suspension calcination method is efficient for sulfur removal: 84.21% of S was removed after calcination at 1000°C for 2 min. During the calcination process, diaspore and pyrite were transferred to α-Al2O3, magnetite, and hematite. The phase transformation of pyrite follows the order FeS2 → Fe3O4 → Fe2O3, and the iron oxides and silica were converted into iron silicate. In the alkali-soluble desilication process, the optimum condition was an alkali solution concentration of 110 g/L, a reaction time of 20 min, and a reaction temperature of 95°C. The corresponding desilication ratio and alumina loss ratio were 44.9% and 2.4%, respectively, and the alumina-to-silica mass ratio of the concentrate was 7.9. The Al2O3·2SiO2, SiO2, and Al2O3 formed during the calcination process could react with Na OH solution, and their activity decreased in the order of Al2O3·2 SiO2, SiO2, and Al2O3.

关键词： low-grade bauxite sulfur suspension calcination alkali-soluble desilication Bayer process

Research on the dynamic characteristics of pneumatic proportional regulator in pneumatic-loading system and design of fuzzy adaptive controller

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Science China(Technological Sciences) 2022年第4期65卷 956-965页

作者： WANG Na XU LuYu xie fei SHI Yan WANG YiXuan Engineering Training Center Beihang UniversityBeijing 100191China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Department of Pulmonary and Critical Care Medicine Chinese PLA General HospitalBeijing 100191China

Pneumatic proportional control servo regulator is the core component of a pneumatic-loading experimental system,which is very important in solving the overcharging ***,previous research on control of pneumatic proportional regulator in a pneumatic-loading experimental system led to failure in analysis of the influence of opening error of the switch regulator because it did not analyze the regulator basic working principle and *** traditional control method cannot fully solve the overcharging problem nor ensure adequate control performance of the *** seriously studying the working principle and key mechanical parameters of the valve,a fuzzy parameter-adaptive controller is designed by introducing a linear mixture of the pressure and opening errors of the switch regulator to reduce pressure overshoot and optimize its control *** to the fuzzy-control strategy based on the working characteristics and mechanical parameters of the valve,the overshoot phenomenon of the pneumatic-loading system is solved,and the pressure overshoot is *** error of the output air pressure of the regulator is 1.24%,which is *** adjustable pressure range of the regulator is 0.2–0.6 *** maximum deviation is 0.012 *** linearity of the case is 1.34%F.S.

关键词： pneumatic proportional servo regulator pneumatic-loading experimental system mathematical model fuzzy parameter-adaptive controller opening error of the switch regulator

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