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A class of epidemic virus transmission population dynamic system

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Applied mathematics and mechanics(English Edition) 2017年第8期38卷 1181-1190页

作者： Cheng OUYANG min ZHU Jiaqi mo Faculty of Science Huzhou UniversityHuzhou 313000Zhejiang ProvinceChina School of mathematics and Computer Science Anhui Normal UniversityWuhu 241003Anhui ProvinceChina

A class of epidemic virus transmission population dynamic system is considered. Firstly, using the functional homotopic analysis method, an initial approximate function is selected. Then, the arbitrary order approximate analytic solutions are obtained successively. Finally, the accuracy of the obtained approximate analytic solutions is described. The influence of the various physical parameters for the epidemic virus transmission population dynamic system is discussed.

关键词： epidemic approximate analytic successively perturbation arbitrary qualitative asymptotic attractive manifold

Discrepancies and error evaluation metrics for machine learning interatomic potentials

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npj Computational materials 2023年第1期9卷 533-545页

作者： Yunsheng Liu Xingfeng He Yifei mo Department of materials Science and Engineering University of MarylandCollege ParkMDUSA

machine learning interatomic potentials(mLIPs)are a promising technique for atomic *** small errors are widely reported for mLIPs,an open concern is whether mLIPs can accurately reproduce atomistic dynamics and related physical properties in molecular dynamics(mD)*** this study,we examine the state-of-the-art mLIPs and uncover several discrepancies related to atom dynamics,defects,and rare events(rEs),compared to ab initio *** find that low averaged errors by current mLIP testing are insufficient,and develop quantitative metrics that better indicate the accurate prediction of atomic dynamics by *** mLIPs optimized by the rE-based evaluation metrics are demonstrated to have improved prediction in multiple *** identified errors,the evaluation metrics,and the proposed process of developing such metrics are general to mLIPs,thus providing valuable guidance for future testing and improvements of accurate and reliable mLIPs for atomistic modeling.

关键词： properties methods testing

ON THE CONVErGENCE OF ImPLICIT DIFFErENCE SCHEmES FOr HYPErBOLIC CONSErVATION LAWS

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Journal of Computational mathematics 2002年第2期20卷 121-128页

作者： Hua-zhong Tang Hua-mo Wu School of mathematical Sciences Peking UniversityBeijing 100871China LSEC ICMSECAcademy of Mathematics and System SciencesChinese Academy of SciencesBeijing 100080China

Discusses the treatment of implicit difference approximations to hyperbolic conservation laws with non-convex flux. Information on weighted implicit difference schemes; Convergence of difference scheme; Establishment ... 详细信息

关键词： conservation laws weighted implicit schemes entropy solution

The giant tin polymetallic mineralization in southwest China:Integrated geochemical and isotopic constraints and implications for Cretaceous tectonomagmatic event

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Geoscience Frontiers 2020年第5期11卷 1593-1608页

作者： Yanbin Liu Lifei Zhang Xuanxue mo m.Santosh Guochen Dong Hongying Zhou moE Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space SciencesPeking UniversityBeijing 100871China State Key Laboratory of Geological Processes and mineral resources And School of Earth Science and ResourcesChina University of Geosciences(Beijing)Beijing 100083China Department of Earth Sciences University of AdelaideSA5005Australia Tianjin Institute of Geology and mineral resources China Geological SurveyTianjin 300170China

The Gejiu-Bozushan-Laojunshan W-Sn polymetallic metallogenic belt(GBLB)in southeast Yunnan Province is an important part of the southwestern Yangtze Block in South *** polymetallic mineralization in this belt includes the Niusipo,malage,Songshujiao,Laochang and Kafang ore fields in the Gejiu area which are spatially and temporally associated with the Kafang-Laochang and Songshujiao granite *** granites are characterized by variable A/CNK values(mostly>1.1,except for two samples with 1.09),high contents of SiO2(74.38-76.84 wt.%)and Al2 O3(12.46-14.05 wt.%)and variable CaO/Na2 O ratios(0.2-0.65)as well as high zirconδ18O values(7.74‰-9.86‰),indicative of S-type *** rocks are depleted in rb,Th,U,Ti,LrEE[(La/Yb)N=1.4-20.51],Ba,Nb,Sr,and Ti and display strong negative Eu and Ba *** rocks possess high rb/Sr and rb/Ba ratios,relatively low initial 87Sr/86Sr ratios(0.6917-0.7101),and less radiogenicεNd(t)values(-8.0 to-9.1).The zircon grains from these rocks show negativeεHf(t)values in the range of-3.7 to-9.9 with mean TDm2(Nd)and TDm2(Hf)values of 1.57 Ga and 1.55 *** show initial 207Pb/204Pb ranging from15.69 to 15.71 and 206Pb/204Pb from 18.36 to *** from Songshujiao granites exhibits higher U and lower Th/U ratios,lowerδ18O values and higherεHf(t)values than those of the zircon grains in the KafangLaochang *** geochemical and isotopic features indicate that the Laochang-Kafang granites originated by partial melting of mesoproterozoic crustal components including biotite-rich metapelite and metagraywacke,whereas the Songshujiao granites were derived from mesoproterozoic muscovite-rich metapelite crustal *** zircon grains from the Songshujiao,Laochang and Kafang granites have high-U concentrations and their SImS U-Pb ages show age scatter from 81.6 ma to 88.6 ma,80.7 ma to 86.1 ma and 82.3 ma to 87.0 ma,suggesting formation earlier than the monazite and *** SImS U-Pb ages and Th-Pb ag

关键词： S-type granite SImS monazite and zircon geochronology Cassiterite U–Pb age Zircon Hf–O isotope Sr–Nd–Pb isotope Yangtze Block

Changes in Vegetation and Assessment of meteorological Conditions in Ecologically Fragile Karst Areas

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Journal of meteorological research 2021年第1期35卷 172-183页

作者： Yanli CHEN Weihua mo Yonglin HUANG Jianfei mo Xiaohan HUANG Xiumei WEN Institute of meteorological Sciences Guangxi Zhuang Autonomous Region(GZAR)Meteorological BureauNanning 530022 Hechi meteorological Service GZAR Meteorological BureauHechi 547000 College of Geography and Planning Nanning Normal UniversityNanning 530001

meteorological conditions have an important impact on changes of vegetation in ecologically fragile karst *** study aims to explore a method for quantitative evaluation of these meteorological conditions. We analyzed the changing trend of vegetation during 2000–2018 and the correlations between vegetation changes and various meteorological factors in karst rocky areas of Guangxi Zhuang Autonomous region, China. Key meteorological factors in vegetation areas with varying degrees of improvement were selected and evaluated at seasonal timescale. A quantitative evaluation model of comprehensive influences of meteorological factors on vegetation was built by using the partial least-square regression(PLS). About 91.45% of the vegetation tended to be improved, while only the rest 8.55% showed a trend of degradation from 2000 to 2018. Areas with evident vegetation improvement were mainly distributed in the middle and northeast, and those with obvious vegetation degradation were scattered. meteorological factors affecting vegetation were significantly different among the four seasons. Overall, high air humidity, small temperature difference in spring and autumn, and low daily minimum temperature and air pressure were favorable conditions. Low temperature in winter as well as high temperature in summer and autumn were unfavorable conditions. The Climate Vegetation Index(CVI) model was established by PLS using the maximum, minimum, and average temperatures;vapor pressure;rainfall;and air pressure as key meteorological factors. The Enhanced Vegetation Index(EVI) was well fitted by the CVI model, with the average coefficient of determination(r2) and root mean square error(rmSE) of 0.856 and 0.042, respectively. Finally, an assessment model of comprehensive meteorological conditions was built based on the interannual differences in CVI. The meteorological conditions in the study area in 2014 were successfully evaluated by combining the model and selected seasonal key meteo

关键词： karst rocky area vegetation change ecologically fragile meteorological conditions

Designing Bézier surfaces minimizing the L^2-norm of the Gaussian curvature

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第1期8卷 142-148页

作者： mo Guo-liang WU ming-hua Department of Information and Computational Science Zhejiang University City College Hangzhou 310015 China

In freeform surface modelling, developable surfaces have much application value. But, in 3D space, there is not always a regular developable surface which interpolates the given boundary of an arbitrary piecewise smooth closed curve. In this paper, tensor product Bézier surfaces interpolating the closed curves are determined and the resulting surface is a minimum of the functional defined by the L2-integral norm of the Gaussian curvature. The Gaussian curvature of the surfaces is minimized by the method of solving nonlinear optimization problems. An improved approach trust-region form method is proposed. A simple application example is also given.

关键词： ensor product polynomial surfaces Gaussian curvature L^2-integral norm Texture mapping Nonlinear optimization

Comparison between chikungunya and dengue viruses transmission based on a mathematical model

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International Journal of Biomathematics 2017年第6期10卷 255-276页

作者： Hyun mo Yang Departamento de matematica Aplicada Universidade Estadual de Campinas Praca Sergio Buarque de Holanda 651 CEP 13083-859 Campinas Sao Paulo Brazil

Chikungunya and dengue viruses are transmitted by mosquitoes of genus Aedes. Based on a mathematical model dealing with arboviruses transmission that encompasses human and mosquito populations, the risks of dengue and chikungunya infections are compared. By the fact that chikungunya virus attains high viral load earlier than dengue virus in both humans and mosquitoes, the potential risk of chikungunya could be higher than the dengue infection. The risk of arboviruses infections is assessed by the reproduction number r, which is obtained by the next generation matrix method and routh-Hurwitz criteria.

关键词： reproduction number partial reproduction numbers stability of equilibriumpoints next generation matrix routh-Hurwitz criteria.

mechanical behavior of segment rebar of shield tunnel in construction stage

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第7期9卷 888-899页

作者： Jun-sheng CHEN Hai-hong mo Department of Civil Engineering South China University of Technology Guang＇zhou 510640 China State Key Laboratory of Subtropical Building Science South China University of Technology Guang＇zhou 510640 China

In this paper, a 3D finite element （FE） program ADINA was applied to analyzing a tunnel with 9 segment tings. The loads acting on these segment tings included the squeezing action of tail brush of shield machine under attitude deflection, the jacking forces, the grouting pressure and the soil pressure. The analyses focused on the rebar stress in two statuses：（1） normal construction status without shield machine squeezing; （2） squeezing action induced by shield machine under attitude deflection. The analyses indicated that the rebar stress was evidently affected by the construction loads. In different construction status, the rebar stress ranges from -80 mPa to 50 mPa, and the rebar is in elastic status. Even some cracks appear on segments, the stress of segment rebar is still at a low level. It is helpful to incorporate a certain quantity of steel fiber to improve the anti-crack and shock resistance performance.

关键词： Shield tunnel Construction Segment rebar Finite element (FE) analysis

Consensus problems on networks with free protocol

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Chinese Physics B 2021年第7期30卷 171-177页

作者： Xiaodong Liu Lipo mo School of mathematics and Statistics Beijing Technology and Business UniversityBeijing 100048China Key Laboratory of Power Big Data of Guizhou Province Guizhou Institute of TechnologyGuiyang 550003China

In the real world,rule makers can only restrict,not completely control the behavior of the governed,while the governed can only choose their behavior patterns under these *** this paper,we design a new control protocol called free protocol to describe this ***,we calculate consensus probabilities based on the information of the interaction ***,sufficient conditions are obtained for all agents converging to a same value with probability ***,numerical simulation results are given to verify the above results.

关键词： multi-agent systems random protocol consensus with probability one