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A Note on Abelian Extensions

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wuhan {1. Journal of Natural Sciences 2008年第1期13卷 6-8页

作者： YU Chuxiong1,2. fan yun3 1. {2. of mathematics and statistics, wuhan university, wuhan 430072. hubei, china 2. {2. of mathematics and Computer Science, Jianghan university, wuhan 430056, {12., china 3. {2. of mathematics and statistics, Huazhong Normal university, wuhan 430079, {12., china school of {1. and {2. Wuhan University Wuhan 430072 Hubei China

Let K/Q be any abelian extension where Q is the field of rational numbers. By Galois theory and the Frobenius formula for induced characters, we prove that there exists a metabelian group G and an irreducible characte... 详细信息

关键词： abelian extensions metabelian groups induced characters Galois groups

An Overview on Wavelet Software Packages

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wuhan {1. Journal of Natural Sciences 2001年第Z1期6卷 593-600页

作者： fan Qi\|bin 1. Li Hong {1.1. school of {{1. and statistics, wuhan university, wuhan 430072. china {1. school of Electronic Information, wuhan university, wuhan 430072. china school of {1. and {2. Wuhan University Wuhan China school of Electronic Information Wuhan University Wuhan China

Wavelet analysis provides very powerful problem\|solving tools for analyzing, encoding, compressing, reconstructing, and modeling signals and images. The amount of wavelets\|related software has been constantly multiplying. Many wavelet analysis tools are widely available. This overview represents a significant survey for many currently available packages. It will be of great benefit to engineers and researchers for using the toolkits and developing new software. The beginner to learning wavelets can also get a great help from the review. If you browse around at some of the Internet sites listed in the reference of this paper, you may find more plentiful wavelet resources.

关键词： wavelet transforms image compression matching pursuit lifting MATLAB

A theorem of Fong's type for graded algebras

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Science china {1. 2005年第5期48卷 577-582页

作者： fan {1. & {2. ping school of mathematics and statistics, Central china Normal university, wuhan 430079, china school of Mathematical Science, Nankai university, Tianjin 300071. china 1. school of {1. and {2. Central China Normal University 430079 Wuhan China 2. {1. of Mathematical Science Nankai University 300071 Tianjin China

Let G be a finite p-solvable group and k be an algebraic closed field of characteristic p. It is proved that any projective indecomposable module of a G-graded k-algebra is an induced module of a module of the subalgebra graded by a Hall p′-subgroup. A necessary and sufficient condition for the indecomposability of an induced module from a Hall p′-subgroup is obtained.

关键词： group graded algebra indecomposable induced module primitive idempotent.

Equivalence problem for Bishop surfaces

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Science china {1. 2010年第3期53卷 687-700页

作者： HUANG XiaoJun 1, & YIN WanKe 2.1 Department of mathematics, Rutgers university, New Brunswick, NJ 08902. USA 2.{2. of mathematics and statistics, wuhan university, wuhan 430072. china 1. Department of mathematics Rutgers University New Brunswick NJ 08902 USA2. School of Mathematics and Statistics Wuhan University Wuhan 430072 China

The paper has two parts. We first briefly survey recent studies on the equivalence problem for real submanifolds in a complex space under the action of biholomorphic transformations. We will mainly focus on some of the recent studies of Bishop surfaces, which, in particular, includes the work of the authors. In the second part of the paper, we apply the general theory developed by the authors to explicitly classify an algebraic family of Bishop surfaces with a vanishing Bishop invariant. More precisely, we let M be a real submanifold of C 2.defined by an equation of the form w = zz + 2.e(z s + az s+1.) with s≥ 3 and a a complex parameter. We will prove in the second part of the paper that for s≥ 4 two such surfaces are holomorphically equivalent if and only if the parameter differs by a certain rotation. When s = 3, we show that surfaces of this type with two different real parameters are not holomorphically equivalent.

关键词： equivalence problem Bishop surface Chern-Moser theory elliptic and hyperbolic complex tangents normal form and modular space

A numerical study on nonlinear propagation and short-term variability of the migrating diurnal and semidiurnal tides

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Chinese Science Bulletin 2005年第17期50卷 1940-1948页

作者： HUANG Chunming1.2. ZHANG Shaodong1.2.& YI fan1.2.1. school of Electronic Information, {2. Universiy, {2. 430079, china 2. Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, wuhan university, {2. 430079, china school of Electronic Information Wuhan University Wuhan 430079 China Key Laboratory of Geospace Environment and Geodesy Ministry of Education Wuhan University Wuhan 430079 China

By using a three-dimensional fully nonlinear numerical model in spherical coordinates and taking the linear steady solutions of the migrating diurnal and semidi-urnal tides in January from the Global-Scale Wave Model (GSWM) as the initial values, we simulate the linear and nonlinear propagations of the migrating diurnal and semidi-urnal tides in the atmosphere from the ground to the lower thermosphere. A comparison of our simulations with the results of GSWM is also presented. The simulation results show that affected by the nonlinearity, the migrating diurnal and semidiurnal tides propagating in the middle and upper atmosphere exhibit evident short-term variability. The nonlinear interactions between the migrating tides and the background atmosphere can obviously alter the background wind and temperature fields, which suggests that the nonlin-ear propagations of the migrating diurnal and semidiurnal tides impact significantly on the transient dynamical and thermal structures of the background middle and upper at-mosphere and the nonlinear effect is an important cause of the difference between the results of GSWM and observa-tions.

关键词：大气非线性传播数学模型可变性温度场

Fabrication of Ti_2.lC by Spark Plasma Sintering from Elemental Powders and Thermodynamics Analysis of Ti-Al-C System

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Journal of wuhan university of Technology(Materials Science) 2007年第2期22卷 325-328页

作者：王苹 State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology

A ternary-layered carbide Ti2.lC material could be synthesized by spark plasma sintering（SPS） technology using elemental powder mixture of Ti, Al and active carbon. By means of XRD and SEM, phases were identified and microscopically evaluated. The experimental results show that the main phase in the product was fully crystallized Ti2.lC with small particle size when sintered at 1.0}0℃. The synthesis temperature of SPS was 2.0-400℃ lower than that of hot pressing （HP） or hot isostatic pressing （HIP）. Through thermodynamics calculations, the mechanism of Ti2.lC was studied by calculating changes of Gibbs free energy of reactions.

关键词： Ti2.lC spark plasma sintering elemental powder thermodynamics analysis

C@Ag core‒shell structure as lubricating additives towards high efficient lubrication

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Friction 2024年第9期12卷 1991-2003页

作者： Dong AO Xiaoqiang fan Minhao {1. Key Laboratory of Advanced Technologies of Materials(Ministry of Education) School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Tribology Research Institute School of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Efficient cooperative lubrication can be achieved via the introduction of core‒shell structure lubricant additives with hard core and soft shell,for obtaining the expected anti-wear performance from the structural changes in the friction *** this study,C@Ag microspheres with a core‒shell structure were prepared by the redox method with carbon spheres as the core and Ag nanoparticles as the *** tribological behaviors as base oil(G1.30)additive with different concentrations were investigated in *** with base oil,the addition of C@Ag particles at 0.5 wt%can reduce the coefficient of friction(COF)and wear volume(Wv)up to 1..5%and 88%,*** importantly,C@Ag particles provide superior lubrication performance to single additive(like carbon sphere(CS)and Ag nanoparticle).C@Ag core‒shell particles contribute to the formation of tribo-film by melt bonding of flexible Ag and carbon sphere(CS)toward excellent self-repair performance and high-efficiency ***,core‒shell structural nanoparticles with hard-core and soft-shell hold bright future for high-performance lubrication application.

关键词： C@Ag microspheres tribo-film self-repair performance high-efficiency lubrication

Flexural-tensile Properties of Layered Steel Fiber Reinforced Rubber Concrete

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Journal of wuhan university of Technology(Materials Science) 2009年第5期24卷 846-848页

作者：易贤仁 school of Sciences Wuhan University of Technology

Layered steel fiber reinforced rubber concrete （LSFRRC）, a new type of pavement concrete based on the requirements of national standard were experimentally researched. The different properties of flexural-tensile strength from plain concrete （PC）, rubber concrete （RC）, layered steel fiber reinforced concrete （LSFRC） and LSFRRC were presented. Experimental results show that the tensile strength of LSFRRC is improved by 4.1.0} compared with PC, by 1..75% compared with RC. The load-deflection curve on flexural-tensile propertiesis put forward. The flexural-tensile toughness index I1. of LSFRRC is improved 1..32.times compared with PC.

关键词： RC LSFRRC flexural-tensile strength load-deflection curve experimental re-search

Mechanical Properties of Layered Steel Fiber and Hybrid Fiber Reinforced Concrete

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Journal of wuhan university of Technology(Materials Science) 2008年第5期23卷 733-736页

作者：卢哲安 hubei Key Laboratory of Roadway Bridge and Structure Engineering Wuhan University of Technology

To explore a new structure form of fiber reinforced concrete, namely, the layered steel fiber and layered hybrid fiber reinforced concrete （LSFRC and LHFRC）, the mechanical properties of LSFRC and LHFRC, such as compressive strength, tensile strength, flexural strength, fatigue and durability were focused on. The experimental results show that LSFRC and LHFRC can improve the flexural strength of concrete by 2.%-50%. In the aspect of improving the flexural strength of concrete, adulterant rate has more obvious effect than length/diameter ratio. Double logarithmic fatigue equation considered liveability was founded. The impermeability of LHFRC is superior to LSFRC and plain concrete （C）. However, the porosity of LHFRC is lower than LSFRC and C. The shrinkage of LHFRC at every age is obviously lower than C. The antifreeze durability of LHFRC is also better than C.

关键词： layered steel fiber reinforced concrete mechanical properties layer hybrid fiber reinforced concrete