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Journal of Wuhan university of technology(Materials science) 2011年第6期26卷 1215-1221页

作者：陈俊 College of Civil and Transportation Engineering Hohai University

We established a user-defined micromechanical model using discrete element method （DEM） to investigate the cracking behavior of asphalt concrete （AC）. Using the ＂Fish＂ language provided in the particle flow code in 3-Demensions （PFC3D）, the air voids and mastics in asphalt concrete were realistically built as two distinct phases. With the irregular shape of individual aggregate particles modeled using a clump of spheres of different sizes, the three-dimensional （3D） discrete element model was able to account for aggregate gradation and fraction. Laboratory uniaxial complex modulus test and indirect tensile strength test were performed to obtain input material parameters for the numerical simulation. A set of the indirect tensile test were simulated to study the cracking behavior of AC at two levels of temperature, i e, -10 ℃ and 15 ℃. The predicted results of the numerical simulation were compared with laboratory experimental measurements. Results show that the 3D DEM model is able to predict accurately the fracture pattern of different asphalt mixtures. Based on the DEM model, the effects of air void content and aggregate volumetric fraction on the cracking behavior of asphalt concrete were evaluated.

关键词： discrete element method asphalt concrete cracking behavior three-dimensional simulation micromechanics

Mechanical Property and Microstructural Characterization of C-Mn-Al-Si Hot Dip Galvanizing TRIP Steel

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Journal of Iron and Steel Research International 2012年第8期19卷 29-36页

作者： JIANG Hai-tao1, DING Wei1,2, TANG Di1, huang Wei1 (1. National Engineering Research Center for Advanced Rolling technology, university of science and technology Beijing, Beijing 100083, china 2. school of Material and Metallurgy, Inner Mongolia university of science and technology, Baotou 014010, Inner Mongolia, china) National Engineering Research Center for Advanced Rolling technology University of Science and Technology Beijing Beijing China school of Material and Metallurgy Inner Mongolia University of Science and Technology Baotou Inner Mongolia China

Mechanical properties and microstructure in high strength hot dip galvanizing TRIP steel were investigated by optical microscope (OM), transmission electron microscope (TEM), X-ray diffraction (XRD), dilatometry and mechanical testing. On the heat treatment process of different intercritical annealing (IA) temperatures, isothermal bainitic transformation (IBT) temperatures and IBT time, this steel shows excellent mechanical properties with tensile strength over 780 MPa and elongation more than 22%. IBT time is a crucial factor in determining the mechanical properties as it confirms the bainite transformation process, as well as the microstructure of the steel. The microstructure of the hot dip galvanizing TRIP steel consisted of ferrite, bainite, retained austenite and martensite during the short IBT time. The contents of ferrite, bainite, retained austenite and martensite with different IBT time were calculated. The results showed that when IBT time increased from 20 to 60 s, the volume of bainite increased from 14.31% to 16.95% and the volume of retained austenite increased from 13.64% to 16.28%; meanwhile, the volume of martensite decreased from 7.18% to 1.89%. Both the transformation induced plasticity of retained austenite and the hardening of martensite are effective, especially, the latter plays a dominant role in the steel containing 7.18% martensite which shows similar strength characteristics as dual-phase steel, but a better elongation. When martensite volume decreases to 1.89%, the steel shows typical mechanical properties of TRIP, as so small amount of martensite has no obvious effect on the mechanical properties.

关键词： TRIP steel isothermal bainitic transformation martensite mechanical property

Effect of CuO on the Formation Mechanism of Calcium Sulphoaluminate

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Journal of Wuhan university of technology(Materials science) 2008年第4期23卷 518-521页

作者： MA Suhua SHEN Xiaodong huang Yeping ZHONG Baiqian College of Materials science and Engineering.nanjing university of technology Nanjing 210009 China

Calcium sulphoaluminate was prepared with chemical reagents in this paper. The formation mechanism of calcium sulphoaluminate and effect of CuO on the formation mechanism of calcium sulphoaluminate were investigated by the chemical analysis, X-ray diffraction （XRD）, and differential scanning calorimetry （DSC）. The results show that there are three ways in the formation of calcium sulphoaluminate. CuO can promote the decomposition of calcium carbonate and decrease the formation temperature of calcium sulphoaluminate（C4A3S）. When the burning temperature is below 1 000 ℃, the addition of CuO can promote the formation of calcium sulphoaluminate, while CuO can not favor the formation of calcium sulphoaluminate above 1 000 ℃.

关键词： copper oxide calcium sulphoaluminate formation mechanism

GTA Welds of Iron-Aluminide Based Alloys

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Journal of university of science and technology Beijing 2001年第1期8卷 39-42页

作者： Dechun Gao, Wangyue Yang, Min Dong, Jihua huang, Yuanding huang, Zuqing Sun Material science and Engineering school, university of science and technology Beijing, Beijing 100083, china Material Sci. and Engineering school Univ. of Sci. and Technology Beijing Beijing 100083 China

The weldability of two Fe3Al-based intermetallic alloys and one Fe-16%Al-based (atom fraction) alloy has been investigated for gas tungsten are (GTA) welding on sheets with a thickness of 2 mm. The results indicated that pre-heating and post-annealing treatment were important procedures for retarding cold crack initiation and the propel selection of filler could effectively improve the weldability. For the same alloys with the same welding filler, it is better to choose lower welding current, in another word, lower heat input.

关键词： iron-aluminide gas tungsten arc welding weldability filler

Preparation and characterization of nanostructured Al_2O_3-13wt.%TiO_2 ceramic coatings by plasma spraying

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Rare Metals 2009年第5期28卷 465-470页

作者： WANG Dongsheng TIAN Zongjun SHEN Lida LIU Zhidong huang Yinhui Jiangsu Key Laboratory of Precision and Micro-Manufacturing technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

Nanostructured and conventional Al2O3-13wt.%TiO2 ceramic coatings were prepared by plasma spraying with nanostructured agglomerated and conventional powders, respectively. The microstructure and microhardness of the coatings were investigated using scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, and microhardness measurement. Meanwhile, the friction and wear behaviors were analyzed and compared using a ball-on-disk tribometer. The results show that the conventional coating has lamellar stacking characteristic and has some pores. However, the nanostructured coating shows a bimodal microstructure, which is composed of both fully melted regions and partially melted regions. According to the microstructural difference, the partially melted regions can be divided into liquid-phase sintered regions （a three-dimensional net or skeleton-like structure： Al2O3-rich submicron particles embedded in the TiO2-rich matrix） and solid-phase sintered regions （remained nanoparticles）. The microstructural characteristics of the liquid-phase sintered region are formed due to the selective melting of TiO2 nanoparticles during plasma spraying. On the other hand, the TiO2 and Al2O3 nanoparticles of the solid-phase sintered regions are all unmelted during plasma spraying. Due to the existence of nanostructured microstructures, the nanostructured coating has a higher microhardness, a lower friction coefficient, and a better wear resistance than the conventional coating.

关键词： surface coating nanostructured coating plasma spraying microstructure microhardness wear resistance

Statistical assessment of H/A target decomposition theorems in radar polarimetry

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science china(Information sciences) 2010年第2期53卷 355-366页

作者： LIU Tao 1,2 , huang GaoMing 1 , WANG XueSong 2 & XIAO ShunPing 2 1 school of Electronic Engineering, Naval university of Engineering, Wuhan 430033, china 2 school of Electronic science and Engineering, National university of Defense technology, Changsha 410073, china school of Electronic Engineering Naval University of Engineering Wuhan China school of Electronic science and Engineering National University of Defense Technology Changsha China

Target decomposition (TD) theorems have been widely applied in radar polarimetry, serving as the bridge between radar measurements and the physical parameters of a scatterer. The H/A target decomposition is one of the most suitable tools for performing data interpretation in the study and characterization of natural scatters. In this paper, the statistics of the parameters of eigenvalue, eigenvector and H/A have been analyzed via a novel method, and the probability density functions (PDF) have been obtained. It is pointed out that all these parameters can be seen as asymptotically nonbiased with respect to the number of looks. In order to reduce the biases for a small number of looks, a novel estimator for the parameters has been proposed. We give the basic theorems for accurate estimation of parameters.

关键词： target decomposition theorems H/A characteristic parameters statistical analysis MLE

Anthropogenic warming is a key climate indicator of rising urban fire activity in china

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National science Review 2024年第5期11卷 110-120页

作者： Qichao Yao Dabang Jiang Ben Zheng Xiaochun Wang Xiaolin Zhu Keyan Fang Lamei Shi Zhou Wang Yongli Wang Linhao Zhong yanyan Pei Amy Hudson Shuai Xu Maowei Bai Xinyan huang Valerie Trouet National Institute of Natural Hazards Ministry of Emergency Management of China Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education School of Forestry Northeast Forestry University Laboratory of Tree-Ring Research University of Arizona Institute of Atmospheric Physics Chinese Academy of Sciences Department of Statistics Colorado State University Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic University Key Laboratory of Humid Subtropical Eco-Geographical Process (MOE) College of Geographic Sciences Fujian Normal University Department of Building Environment and Energy Engineering The Hong Kong Polytechnic University

china, one of the most populous countries in the world, has suffered the highest number of natural disaster-related deaths from fire. On local scales, the main causes of urban fires are anthropogenic in ***, on regional to national scales, little is known about the indicators of large-scale co-varying urban fire activity in china. Here, we present the china Fire History Atlas(CFHA), which is based on 19 947documentary records and represents fires in urban areas of china over the twentieth century(1901–1994).We found that temperature variability is a key indicator of urban fire activity in china, with warmer temperatures being correlated with more urban fires, and that this fire–temperature relationship is seasonally and regionally explicit. In the early twentieth century, however, the fire–temperature relationship was overruled by war-related fires in large urban areas. We further used the fire–temperature relationship and multiple emissions scenarios to project fire activity across china into the twenty-first century. Our projections show a distinct increase in future urban fire activity and fire-related economic loss. Our findings provide insights into fire–climate relationships in china for densely-populated areas and on policy-relevant time scales and they contribute spatial coverage to efforts to improve global fire models.

关键词： fire–climate interactions global warming fire history network urban fires fire management

A quasi-physical algorithm for solving the linear separation problem in n-dimensional space

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Journal of Central South university of technology 2001年第4期8卷 272-277页

作者： huang Jia yuan (College of Computer science, Huazhong university of science and technology, Wuhan 430074, china) College of Computer science Huazhong University of Science and Technology Wuhan China

A quasi physical algorithm was proposed for solving the linear separation problem of point set in n dimensional *** original idea of the quasi physical algorithm is to find an equivalent physical world for the primitive mathematical problem and to observe the vivid images of the motion of matter in it so as to be inspired to obtain an algorithm for solving the mathematical problem. In this work, the electrostatics with two kinds of matter is found to be the equivalent physical world. As a result,the proposed algorithm is evidently more efficient and robust than the famous LMS algorithm and ETL algorithm. The efficiency of the quasi physical algorithm is about 10-50 times of the LMS algorithm’s for representative instances. A typical Boolean valued instance shows that it is hard for ETL algorithm but very easy for the quasi physical *** this instance, point set A and B is {000, 010, 011, 111} and {001,100}, respectively.

关键词： linear separation problem neural network algorithm quasi-physical method electrostatics

A new composite:spray-deposited M2 high speed steel reinforced by WC particles

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International Journal of Minerals,Metallurgy and Materials 1997年第3期11卷 14-17页

作者： ZHANG Liying TIAN Haige huang Thuo WU Chengyi (Material science and Engineering school, university of science and technology Beijing, Beijing 100083, china) Univ of science and technology Beijing Beijing China

The fabrication of the high speed steel matrix composites reinforced by WC particles utilizing the ultrasonicgas atomization and spray-deposition was studied. The change of microstware and mechanical Properties of thecomposites added WC Particles were investigated and analyzed as well. As some results, the WC particles exhibit tWomorphologies (spherical and angular) with different content of WC particles; and with the increase of content of WCparticles, the hardness of the composites increases, yet the bending strength appears a trend of decreasing.

关键词： spray-deposition high speed steel composite

LiCoO_2 electrode/electrolyte interface of Li-ion batteries investigated by electrochemical impedance spectroscopy

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science china Chemistry 2007年第6期50卷 776-783页

作者： Zhuang QuanChao1, 2, XU JinMei1, FAN XiaoYong1, WEI GuoZhen1, DONG QuanFeng1 JIANG YanXia1, huang Ling1 & SUN Shigang1 1 State Key Lab of Physical Chemistry of Solid Surfaces, Department of Chemistry, Xiamen university, Xiamen 361005, china 2 school of Materials science and Engineering, china university of Mining & technology, Xuzhou 221116, china State Key Lab of Physical Chemistry of Solid Surfaces Department of Chemistry Xiamen University Xiamen China school of Materials science and Engineering China University of Mining & Technology Xuzhou China

The storage behavior and the first delithiation of LiCoO2 electrode in 1 mol/L LiPF6-EC:DMC:DEC elec- trolyte were investigated by electrochemical impedance spectroscopy (EIS). It has found that, along with the increase of storage time, the thickness of SEI film increases, and some organic carbonate lithium compounds are formed due to spontaneous reactions occurring between the LiCoO2 electrode and the electrolyte. When electrode potential is changed from 3.8 to 3.95 V, the reversible breakdown of the resistive SEI film occurs, which is attributed to the reversible dissolution of the SEI film component. With the increase of electrode potential, the thickness of SEI film increases rapidly above 4.2 V, due to overcharge reactions. The inductive loop observed in impedance spectra of the LiCoO2 electrode in Li/LiCoO2 cells is attributed to the formation of a Li1-xCoO2/LiCoO2 concentration cell. Moreover, it has been demonstrated that the lithium-ion insertion-deinsertion in LiCoO2 hosts can be well described by both Langmuir and Frumkin insertion isotherms, and the symmetry factor of charge transfer has been evaluated at 0.5.

关键词： Li-ion batteries, LiCoO2, EIS, SEI film, inductance