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THE GLOBAL DUFORT-FRANKEL DIFFERENCE APPROXIMATION FOR NONLINEAR REACTION-DIFFUSION EQUATIONS

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Journal of Computational Mathematics 1998年第3期16卷 275-288页

作者： Lu, BN Wan, GH Guo, bl Xiangtan Univ Inst Computat & Appl Math Xiangtan 411105 Peoples R China Inst Appl Phys & Computat Math Lab Computat Phys Beijing 100088 Peoples R China Shaanzi Normal Univ Dept Math Xian 710062 Peoples R China Inst Appl Phys & Computat Math Ctr Nonlinear Studies Beijing 100088 Peoples R China

In this paper, the initial value problem of nonlinear reaction-diffusion equation is considered. The Dufort-Frankel finite difference approximation for the long time scheme is given for the d-dimensional reaction-diffusion equation with the two different cases. The global solution and global attractor are discussed for the Dufort-Frankel scheme. Moreover properties of the solution are studied. The error estimate is presented in a finite time region and in the global time region for some special cases. Finally the numerical results for the equation are investigated for Allen-Cahn equation and some other equations and the homoclinic orbit is simulated numerically.

关键词： global Dufort-Frankel method reaction-diffusion equation global attractor error estimate numerical experiments

STM image of tungstosilicic acid molecular layer on highly oriented pyrolytic graphite

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Chinese Journal of Chemistry 1995年第6期13卷 493-496页

作者： Zhang, bl Wang, EK CHINESE ACAD SCI CHANGCHUN INST APPL CHEMELECTROANALYT CHEM LABCHANGCHUN 130022JILINPEOPLES R CHINA

Molecular layer of tungstosilicic acid (H4SiW12O40) deposited on freshly-cleaved highly oriented pyrolytic graphite (HOPG) was observed by scanning tunneling microscopy (STM) in air at room temperature. The molecular dimension (11.5 Angstrom) of H4SiW12O40 measured by STM is consistent with known crystallographic parameter. We also imaged the boundary of H4SiW12O40 molecular layer on HOPG showing that molecular layer of H4SiW12O40 was formed. It has been proved that individual tungstosilicic acid species is imaged. The probable reason for the formation of the molecular layer is also discussed.

关键词： tungstosilicic acid HOPG STM

TENSILE PROPERTIES OF COATED CARBON FIBER REINFORCED MAGNESIUM COMPOSITES

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中国有色金属学会会刊：英文版 1997年第3期7卷 87-90页

作者： Zhang, K Wang, YQ Zhou, bl CHINESE ACAD SCI INST MET RESSHENYANG 110015PEOPLES R CHINA ACAD SINICA INT CTR MAT PHYSSHENYANG 110015PEOPLES R CHINA

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关键词： C/Mg composites coating thickness tensile properties

Persistent Currents in Toroidal Single-wall Carbon Nanotubes

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Journal of Materials Science & Technology 1999年第4期15卷 342-344页

作者： Liu, JJ Zhang, G Gu, bl Tsing Hua Univ Dept Phys Beijing 100084 Peoples R China

In this paper the persistent currents of ideal toroidal single-wall carbon nanotubes (TSWNTs) are calculated from the tight-binding model and the periodic boundary conditions. The electronic structure and persistent current of a TSWNT strongly depend on its helicity and longitudinal circumference, making the TSWNTs a geometry-sensitive kind of materials. The interatomic carbonic interactions other than pp pi-type are also studied and are found to introduce more steps to the persistent current. The diamagnetic-paramagnetic transitions occur more frequently, and the persistent current depends on the interaction energy values, while the periodicity of magnetic flux preserves.

关键词： Nanotubes

Biomimetic Study on Helical Fiber Composites

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Journal of Materials Science & Technology 1998年第1期14卷 29-32页

作者： Zhang, K Wang, YQ Zhou, bl Chinese Acad Sci Inst Met Res Shenyang 110015 Peoples R China Acad Sinica Int Ctr Mat Phys Shenyang 110015 Peoples R China

The innovative approach imparting strength and toughness to carbon fiber reinforced polymer composites (CFRP) is put forward from the viewpoint of biomimetics. Helical fibers produced by twisting fiber bundle are arranged in the matrix to simulate the unique structure of natural fibers. The results on the CFRP with helical fiber bundles show that, under the same state of strong fiber/matrix interface, the impact fracture toughness can be improved substantially compared to conventional composites with plain fibers. The beneficial effect is attributed to the helical fiber bundles which act as single fibers of huge diameter effectively increasing the fiber elastic energy.

关键词： Carbon fiber reinforced plastics

Electron–plasmon and electron–magnon scattering in ferromagnets from first principles by combining GW and GT self-energies

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npj Computational Materials 2021年第1期7卷 1619-1632页

作者： Dmitrii Nabok Stefan blügel Christoph Friedrich Peter Grünberg Institut and Institut for Advanced Simulation Forschungszentrum JülichJülich 52425Germany

This work combines two powerful self-energy techniques:the well-known GW method and a self-energy recently developed by us that describes renormalization effects caused by the scattering of electrons with magnons and Stoner *** GT selfenergy,which is fully k-dependent and contains infinitely many spin-flip ladder diagrams,was shown to have a profound impact on the electronic band structure of Fe,Co,and *** the present work,we refine the method by combining GT with the GW *** resulting GWT spectral functions exhibit strong lifetime effects and emergent dispersion *** are in an overall better agreement with experimental spectra than those obtained with GW or GT alone,even showing partial improvements over local-spin-density approximation dynamical mean-field *** performed analysis provides a basis for applying the GWT technique to a wider class of magnetic materials.

关键词： materials theory infinitely

A graph-based representation of knowledge for managing land administration data from distributed agencies–A case study of Colombia

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Geo-Spatial Information Science 2022年第2期25卷 259-277页

作者： Luis M.Vilches-blázquez Jhonny Saavedra Investigación en Computación Instituto Politécnico NacionalMexico CityMexico School of Land Surveying Geodesy and Mapping EngineeringUniversidad Politécnica de MadridMadridSpain

Multiple efforts have been performed worldwide around diverse aspects of land ***,land administration data and systems’notorious heterogeneity remains a longstanding challenge to develop a harmonized *** this sense,the traditional Spatial Data Infrastructures adoption is not enough to overcome this challenge since data sources’heterogeneity implies needs related to harmonization interoperability,sharing,and integration in land administration *** paper proposes a graph-based represen-tation of knowledge for integrating multiple and heterogeneous data sources(tables,shape-files,geodatabases,and WFS services)belonging to two Colombian agencies within a decentralized land administration *** knowledge graphs are developed on an ontology-based knowledge representation using national and international standards for land *** approach aims to prevent data isolation,enable cross-datasets integration,accomplish machine-processable data,and facilitate the reuse and exploitation of multi-jurisdictional datasets in a single approach.A real case study demonstrates the applicability of the land administration data cycle deployed.

关键词： Land administration knowledge graph ontology heterogeneity data integration

The AiiDA-KKR plugin and its application to highthroughput impurity embedding into a topological insulator

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npj Computational Materials 2021年第1期7卷 108-116页

作者： Philipp Rüßmann Fabian Bertoldoand Stefan blügel Peter Grünberg Institut and Institute for Advanced Simulation Forschungszentrum Jülich and JARAD-52425 JülichGermany

The ever increasing availability of supercomputing resources led computer-based materials science into a new era of highthroughput ***,Pizzi et *** the AiiDA framework that provides a way to automate calculations while allowing to store the full provenance of complex workflows in a *** present the development of the AiiDA-KKR plugin that allows to perform a large number of ab initio impurity embedding calculations based on the relativistic full-potential Korringa-Kohn-Rostoker Green function *** capabilities of the AiiDA-KKR plugin are demonstrated with the calculation of several thousand impurities embedded into the prototypical topological insulator *** results are collected in the JuDiT database which we use to investigate chemical trends as well as Fermi level and layer dependence of physical properties of *** includes the study of spin moments,the impurity’s tendency to form in-gap states or its effect on the charge doping of the *** properties depend on the detailed electronic structure of the impurity embedded into the host crystal which highlights the need for ab initio calculations in order to get accurate predictions.

关键词： method topological embedding

Remarks on the nonlinear Schrodinger equations in plasma

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Chinese Science Bulletin 1997年第22期42卷 1875-1877页

作者： Guo, bl Wu, YH Inst Appl Phys & Computat Math Beijing 100088 Peoples R China

CONSIDER the following nonlinear Schrodinger equation: （SP）{iΔφt+Δ2φ+β(|φ|2pφ)=0,x∈R2,t>0, （1,1） φ|i=0=φ0（x）, （1,2）where p>0, β∈R are constants, φ0∈H3 （R2）. For the problem arising from nonline... 详细信息

关键词： Schrodinger equations existence blow-up.