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Synthesis of Cr-Al_2._3 Cermet Selective Surfaces Coated by SnO_2.Thin Film by Air Plasma Spraying

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稀有金属材料与工程 2012年第S1期41卷 272-275页

作者： Zhu Zhenqi,Cheng Xudong,Li Guanglei school of Materials science and {2.,wuhan university of {2.,wuhan 43.070,china wuhan Univ Technol State Key Lab Adv Technol Mat Synth & Proc Sch Mat Sci & Technol Wuhan 430070 Peoples R China

High efficient Cr-Al2.3 cermet selective surfaces coated by sol-gel SnO2.thin film for high-temperature application were synthesized by air plasma spraying(APS),followed further heat and polish *** phase composition and micro morphology of coating samples were characterized by X-ray diffractions(XRD),scanning electron microscope(SEM)and roughmeter *** solar absorptance(α)and thermal emittance(ε)were determined by optical spectrum *** results show that Cr-Al2.3 cermet coating has a high absorptivity nearly *** unfortunately,the emissivity of these coatings is nearly 0.50 because of the big thickness and coarse surface prepared by APS ***,once coated SnO2.thin film,the composite coatings exhibit excellent selective absorbing property of α=0.89 and ε=***,SnO2.thin film plays a significant role in decreasing the emissivity of coatings as antireflection *** furthermore,the optical performance shows that more metal content and smooth surface are favorable for the selective absorbing ***,the coatings have excellent bond strength with stainless steel substrate and thermal shock resistance at high temperature.

关键词： selective surfaces SnO2 thin film air plasma spraying

Flexural-tensile Properties of Layered Steel Fiber Reinforced Rubber Concrete

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Journal of wuhan university of {2.(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 4.12. compared with PC, by 13.75% compared with RC. The load-deflection curve on flexural-tensile propertiesis put forward. The flexural-tensile toughness index I10 of LSFRRC is improved 10.32.times compared with PC.

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

Early Age Compressive Strength of Pastes by Electrical Resistivity Method and Maturity Method

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Journal of wuhan university of {2.(Materials science) 2011年第5期26卷 983-989页

作者：肖莲珍 school of Materials science and Engineering Wuhan Institute of Technology

The compressive strength development of Portland cement pastes was investigated by the electrical resistivity method and the maturity *** experiments were carried out on the cement pastes with different water-cement ratios at different curing *** results show that the application of the maturity method has limitation to obtain the *** is found that both of the compressive strength and the electrical resistivity follow hyperbolic trend for all the *** hyperbolic equation of each mix is obtained to estimate the ultimate resistivity value which can probably be *** relationship between electrical resistivity and compressive strength of the cement pastes is established based on the test results and interpreted by the empirical Archie equation and a strength-porosity *** relationship between the electrical resistivity after temperature correction and the compressive strength was linear and independent of curing temperature and water-cement ratio.

关键词： electrical resistivity cement hydration compressive strength maturity method

Determination of the Thermal Expansion Coefficient of Concrete at Early Ages by Using Temperature-stress Testing Machine

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Journal of wuhan university of {2.(Materials science) 2006年第4期21卷 146-149页

作者：霍凯成 Hubei Key Laboratory of Roadway Bridge & Structure Engineering Wuhan University of TechnologyWuhan 430070China

By using the uptodate temperatuer-stress testing machine, the thermal expansion coefficient of concrete at early ages was studied and indicative conclusions were achieved ： temperature rising due to hydration heat is not directly correlated with cracking, but the temperature and stress evolation process should be taken into consideration in the same time. Proper chemical admixtures and mineral cornpasitions can improve the mechanical properties of concrete such as thermal expansion coefficient, which is very indicative in practice.

关键词： concrete coefficient of thermal expansion temperature-stress test

Fractal Analysis of Gas Diffusion Layer in PEM Fuel Cells

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Journal of wuhan university of {2.(Materials science) 2006年第1期21卷 22-25页

作者：石英肖金生 State Key Laboratory of Advanced technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070ChinaSchool of Automation Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070ChinaSchool of Automotive EngineeringWuhan University of Technology Wuhan 430070China

The aim of this study is to show how fractal analysis can be effectively used to characterize the texture of porous solids. The materials under study were carbon papers, the backing material of the gas diffusion layer （GDL） in Proton Exchange Membrane Fuel Cell （PEMFC）. The fractal dimensions were calculated by analyzing data from mercury porosimetry. The polytotrafluoroethylene （PTFE） treated carbon paper shows a significantly high fractal dimension value than pare sample, and the high fractal dimension signifies that the physical complexity of the pore surface is enhanced. The fractal dimension can be used as a valid parameter to monitor the textural evolution of the samples as the treatment progresses, as this behaves in a similar way to other textural parameters. The use of fractal analysis in conjunction with the results of classical characterization methods leads to a better understanding of textural modificatious in the processing of materials.

关键词： PEMFC gas diffusion layer fractal dimension mewury porosimetry

Ni60-SiC Coating Prepared by Plasma Spraying, Plasma Re-melting and Plasma Spray Welding on Surface of Hot Forging Die

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Journal of wuhan university of {2.(Materials science) 2011年第4期26卷 715-718页

作者：王洪福 school of Mechanical Engineering and automation North University of China

In order to produce the hear-resistant inner layer of hot-forging die, plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2. including 10%, 2.%, 30% SiC ceramic powder used as coating material to obtain different Ni-based SiC alloys coating. Micro-structure and micro-hardness analysis of the coating layer were followed, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70% Ni60, 30% SiC powder has best properties with plasma spray welding, in which the micro-hardness can achieve 1100 HV, meanwhile can improve the thermal property of hot-forging die dramatically.

关键词： hot forging die plasma spraying plasma re-melting plasma spray welding thermo- physical properties

Electronic Structure of Doped Trans-Polyacetylene

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wuhan university Journal of Natural {2.s 2002年第1期7卷 51-53页

作者： Ren Da-zhi 1,2. Zhuang Wei 2. Wang Jun 2.1. wuhan university Journals Press,wuhan 430072.Hubei,china 2. school of Physics and technology, wuhan university, wuhan 430072.Hubei,china wuhan university Journals Press Wuhan Hubei China school of Physics and technology Wuhan University Wuhan Hubei China

The behavior of electronic structures of doped trans-polyacetylene is revealed by a simple method. (C2.H2.)+n is used to simulate p-type doped trans-polyacetylene at various doping concentrations. The electronic structure is calculated, by CNDO/2.method. These calculations show that at low doping level, the decrease of electronic energy compensates the increase of elastic energy, thus the bond alternation exists, and the charge carriers are solitons. When doping level is high, the increase of elastic energy is larger than the decrease, of electronic energy, the bond alternation disappears, solitons no longer exist, and polyacetylene is in a metalic state.

关键词： trans polyacetylene CNDO/2 electronic structure doped

Exploring non-equilibrium statistical ensembles

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science Bulletin 2011年第34期56卷 3654-3660页

作者： BI Qiao & LIU Jie Department of Physics, school of science, {2. university of technology, wuhan 43.070, china Department of Physics School of Science Wuhan University of Technology Wuhan China

Since Gibbs synthesized a general equilibrium statistical ensemble theory, generalizing the Gibbsian theory to non-equilibrium phenomena has been a dream for some theorists. However, the status of the theory for the non-equilibrium ensemble formalism is not as well established as the Gibbsian ensemble theory. In this work, we explore the formalism behind the non-equilibrium statistical ensemble theory based on the sub-dynamic kinetic equation originating from the Brussels-Austin school and developed further by others. The key is establishing a similarity transformation between Gibbsian ensembles and the sub-dynamic ensemble. Using this way, we study a spin-Boson model with strong coupling. A reduced density operator for the canonical ensemble can be easily obtained and the relevant decoherence-free property is revealed.

关键词： subdynamics statistical ensemble non-equilibrium statistical physics

Hierarchical Classification of Chinese Documents Based on N grams

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wuhan university Journal of Natural {2.s 2001年第Z1期6卷 416-422页

作者： Zhou Shui geng 1, Guan Ji hong 2. He Yan xiang 2.1. State Key Laboratory of Software Engineering, wuhan university, wuhan 430072. china 2. school of Computer science, wuhan university, wuhan 430072. china State Key Laboratory of Software Engineering Wuhan University Wuhan China school of Computer science Wuhan University Wuhan China

We explore the techniques of utilizing N gram information to categorize Chinese text documents hierarchically so that the classifier can shake off the burden of large dictionaries and complex segmentation processing, and subsequently be domain and time independent. A hierarchical Chinese text classifier is implemented. Experimental results show that hierarchically classifying Chinese text documents based N grams can achieve satisfactory performance and outperforms the other traditional Chinese text classifiers.

关键词： Chinese text classification N grams feature selection hierarchical classification