检索结果-南通市图书馆

Almost nonnegative curvature operator and cohomology rings

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2016年第5期11卷 1259-1274页

作者： Martin HERRMANN Fakultat fur Mathematik Karlsruher Institut fur Technologie Kaiserstraβe 89-93 76133 Karlsruhe Germany

We give a survey of results on the construction of and obstructions to metrics of almost nonnegative curvature operator on closed manifolds and results on the cohomology rings of closed, simply-connected manifolds with a lower curvature and upper diameter bound. The latter is motivated by a question of Grove whether these condition imply finiteness of rational homotopy types. This question has answers by F. Fang-X. Rong, B. Totaro and recently A. Dessai and the present author.

关键词： Nonnegative curvature homogeneous spaces curvature operator almost nonnegative curvature

Relationship Between Oct agonal Quasicrystal and β-Mn Type Crystal in Cut Description

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 1996年第3期13卷 199-202页

作者： LI Fang-hua CHENG Yi-fan institute of Physics Chinese Academy of SciencesBeijing 1000801 Max-Planck-institut fur Metallforschung Institut fur Werkstoff-WeissenschaftSeestrasse 9270147 StuttgartGermany

The transformation from the octagonal lattice to a square lattice is demonstrated straightforward under the cut description by introducing a peculiar linear phason *** calculated lattice parameter of the ft-Mn structure from the edge length of squares and rhombi forming the octagonal quasilattice is in agreement with experimental results.

关键词： strain. agonal lattice

BACKWARD ERROR ANALYSIS OF SYMPLECTIC INTEGRATORS FOR LINEAR SEPARABLE HAMILTONIAN SYSTEMS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2002年第5期20卷 449-460页

作者： PeterGrtz institut fur Praktische Mathematik Universitat Karlsruhe Englerstrabe 德国 Karlsruhe 276128

Presents a study that analyzed the symplecticness, stability and asymptotic of Runge-Kutta, partitioned Runge-Kutta, and Runge-Kutta-Nystr ? m methods applied to linear Hamiltonian systems. Numerical representation of the problem; Results in connection to P-stability; Details of the application of backward error analysis in the study.

关键词： Hamiltonian systems Backward error analysis Symplectic integrators.

CREEP DEFORMATION OF INTERMETALLIC ALLOYS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1995年第Z1期8卷 431-440页

作者： Gerhard Sauthoff(Max-Planck-institut fur Eisenforschung GmbH., D-40074 Dusseldorf,Germany) Max-Planck-institut fur Eisenforschung GmbH Dusseldorf Germany

Intermetallics for structural applications at high temperatures must show a sufficient high temperature strength which is controlled by creep processes. In the first section the creep behaviour of single-phase intermetallic alloys is overviewed with respect to stress and temperature dependence and effects of composition and microstructure. It is shown in particular that creep deformation is controlled by diffusion. The second section refers to multiphase intermetallic alloys, and both particulate and non-particulate alloys are regarded. Data are presented for single-phase and multiphase alloys based on B2 phases and lesscommon phases and the consequences of diffusion control for alloy design are discussed.

关键词： creep B2 phases NiAl particulate alloys,multiphase alloys

Clustering of voltage-gated ion channels as an evolutionary trigger of myelin formation

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第8期19卷 1631-1632页

作者： Henrike Ohm Simone Rey Christian Klambt institut fur Neuro-und Verhaltensbiologie MunsterGermany

Neurons carry apical dendrites that perceive information and a basal axon that transmits the computed information towards its to *** axon originates at the axon hillock which is followed by the axon initial ***,action potentials are initiated that are based on millisecond long openings of specific voltagegated sodium and potassium channels that are conserved in all parahoxozoa(Placozoa,Cnidaria,Bilateria)(Li et al.,2015).

关键词： initiated carry potassium

A glance at three-dimensional Alexandrov spaces

在线全文

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2016年第5期11卷 1189-1206页

作者： Fernando GALAZ-GARCIA institut fur Algebra und Geometrie Karlsruher Institut fiir Technologie (KIT) Karlsruhe Germany

We discuss the topology and geometry of closed Alexandrov spaces of dimension three.

关键词： Alexandrov space group action 3-manifold

Spaces and moduli spaces of Riemannian metrics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Mathematics in China 2016年第5期11卷 1335-1343页

作者： Wilderich TUSCHMANN Karlsruher institut fur Technologie (KIT) Fakultat fur Mathematik Institut fiir Algebra und Geometrie Arbeitsgruppe Differentialgeometrie Englerstraβe 2 D-76131 Karlsruhe Germany

These notes present and survey results about spaces and moduli spaces of complete Riemannian metrics with curvature bounds on open and closed manifolds, here focussing mainly on connectedness and disconnectedness prop... 详细信息

关键词： Riemannian metrics moduli spaces sectional curvature positive Ricci curvature positive scalar curvature

On the Estimation of Solutions for Some Linear Systems of Differential Equations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 1998年第1期14卷 41-46页

作者： L. R. Awad E. M. El-Kholy Sh. El-Bendary Universitat Hamburg institut fur Angewandte Mathematik Bundesstraβe 55 20146 Hamburg Germany

In this paper we estimate the solutions of homogeneous linear system of differential equations with unbounded coefficients on the real line R. We also give a necessary and sufficient condition in order that the linear... 详细信息

关键词： Homogeneous linear Unbounded coefficient

Normal and abnormal grain growth in magnesium:Experimental observations and simulations

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第15期47卷 257-270页

作者： Risheng Pei Sandra Korte-Kerzel Talal Al-Samman institut fur Metallkunde und Materialphysik RWTH Aachen UniversityD-52056AachenGermany

Commercial purity as-cast magnesium was hot rolled and subsequently annealed at different temperatures in order to investigate its grain growth behavior and link it to the texture *** at an intermediate temperature of 220℃ gave rise to abnormal grain growth with a few grains reaching a grain diameter 10 times larger than the *** the annealing temperature to 350℃ yielded normal grain *** types of grain growth revealed a strengthening of the(0001) texture *** is hypothesized that a dislocation density gradient after recrystallization grants(0001) grains a size advantage during early stages of *** type of growth will be,however,determined by the mobility of the present grain boundaries and triple junction drag,which are strongly dependent on the annealing *** above hypothesis of the interplay between these parameters was explored through curvature-and re sidual dislocation-density-gradient-driven grain growth simulations using a formerly developed level-set *** simulation outcome suggests that application of such a modeling approach in microstructure studies of magnesium can provide valuable new insights into the problem of grain growth and associated texture evolutio n.

关键词： Pure magnesium Grain growth Texture Dislocation density gradient Level-set modeling