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Prediction method for October 2.03 solar storm

Science china(Technological Sciences) 2006年第5期49卷 629-640页

作者： XIE Yanqiong1, 2. 3, WEI Fengsi1, FENG Xueshang1 & ZHONG Dingkun1, 2.1. State Key Laboratory of Space Weather, center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100080, china 2. Graduate School, Chinese Academy of Sciences, Beijing 100039, china 3. Institute of Meteorology, PLA University of Science and Technology, nanjing 2.1101, china State Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing China Graduate School Chinese Academy of Sciences Beijing China Institute of Meteorology PLA University of Science and Technology Nanjing China

Aiming at two intense shock events on October 2. and 2., 2.03, this paper presents a two-step method, which combines synoptic analysis of space weather ——“observing” and quantitative prediction ——“palpating”, and then uses it to test predictions. In the first step of “observing”, on the basis of observations of the solar source surface magnetic field, interplanetary scintillation (IPS) and ACE spacecraft, we find that the propagation of the shocks is asymmetric relative to the normal direction of their solar sources, and the Earth is located near the direction of the fastest speed and the greatest energy of the shocks. As the two fast ejection shock events, the fast explosion of coronal mass of the extremely high temperature, the strong magnetic field, and the high speed background solar wind are also helpful to their rapid propagation. In the second step of “palpating”, we adopt a new membership function of the fast shock events for the ISF method. The predicted results show that for the onset time of the geomagnetic disturbance, the relative errors between the observational and the predicted results are 1.8% and 6.7%; and for the magnetic disturbance magnitude, the relative errors are 4.1% and 3.1%, re- spectively. Furthermore, the comparison among the predicted results of our two-step method with those of five other prevailing methods shows that the two-step method is advantageous. The results tell us that understanding the physical features of shock propagation thoroughly is of great importance in improving the prediction precision.

关键词： solar storm, interplanetary shock, interplanetary scintillation, two-step method, ISF method.

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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 Technology(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

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Structure and Properties of BaFe_(12.O_(19) Coated Fly Ash Cenospheres by Sol-Gel Process

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Journal of Wuhan University of Technology(materials Science) 2006年第3期21卷 129-131页

作者：曾爱香 Department of materials Science and Technology Changsha University of Science and TechnologyChangsha 410076ChinaState Kay Laboratry of Die and Mould Technology Huazhong University of Science and TechnologyWuhan 430074China

Thin films of barium hexaferrite were prepared on fly ash cenosphere particles by the sol-gel method using Fe（ NO3 ）3 ·9H2., Ba（ NO3 ）2.and citric acid as raw materials. The prepared films were characterized by differential thermal and thermogravimetric analysis （DTA-TG）, X-ray diffraction analysis （XRD）, scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDX）, X-ray photoelectron spectroscopy （XPS）, and vibrating sample magnetometry . The magnetic and structural properties of barium hexaferrite coated cenosphere particles were also studied. The experimental results show that even and continual barium hexaferrite coatings were prepared on fly ash cenospheres , and the magnetic conductivity was imparted to these non-conducting oxide ceramic particles. The low density barium hexaferrite coated cenosphere particles may be atilized for manufacturing microwave absorbing materials.

关键词： barium hexaferrite coating fly ash cenosphere particles sol-gel

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Pathways of birnessite formation in alkali medium

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Science china Earth Sciences 2005年第9期48卷 1438-1451页

作者： FENG Xionghan1, TAN Wenfeng1, LIU Fan1, HUANG Qiaoyun1 & LIU Xiangwen2.1. College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, china 2. Testing center, china University of Geosciences, Wuhan 430074, china College of Resources and Environment Huazhong Agricultural University Wuhan China Testing center China University of Geosciences Wuhan China

Birnessite is a common weathering and oxidation product of manganese-bearing rocks. An O2.oxidation procedure of Mn(OH)2.in the alkali medium has been used to synthesize birnessite. Fast and powder X-ray diffraction (XRD), transmission electron microscopy (TEM), electron diffraction (ED), energy dispersed X-ray analysis (EDAX), infrared spectroscopy (IR) techniques and chemical composition analysis, Eh-pH equilibrium diagram approaches were employed to investigate the reaction process and pathways of birnessite formation. Results showed that the process of the birnessite formation could be divided into four stages: (1) forma- tion stage for hausmannite and feitknechtite, (2. stage of transformation of hausmannite and feitknechtite to buserite, (3) buserite crystal growing stage, and (4) stage of conversion of buser- ite into birnessite. Mn(OH)2.was mainly present as amorphous state only for a short initial time of oxidation reaction. In the oxidation process, buserite formed following two pathways by recrys- tallization after dissolution of the intermediates, and the transformations of the minerals de- pended on the Eh determined by the dissolved O2.concentration on their surfaces. The results are fundamental in further exploration on the mechanism of birnessite formation in the alkali medium. A great practical significance would also be expected with respect to the areas of mate- rial sciences.

关键词： birnessite, pathway of formation, reaction process, Eh-pH diagram, hausmannite, feitknechtite.

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Similar component analysis

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Progress in Natural Science:materials International 2006年第12期16卷 1343-1347页

作者： ZHANG Hong~1**, WANG Xin~1, LI Junwei~2.and CAO Xianguang~1(1. Image center, Astronautics School, BeiHang University, Beijing 100083, china 2. The 2.7th Institute of the Second Academy of china Aerospace Science Industry Corporation, Beijing 100854, china) Image center Astronautics School BeiHang University Beijing 100083 China The 2.7th Institute of the Second Academy of china Aerospace Science Industry Corporation Beijing 100854 China

A new unsupervised feature extraction method called similar component analysis (SCA) is proposed in this paper. SCA method has a self-aggregation property that the data objects will move towards each other to form clusters through SCA theoretically, which can reveal the inherent pattern of similarity hidden in the dataset. The inputs of SCA are just the pairwise similarities of the dataset, which makes it easier for time series analysis due to the variable length of the time series. Our experimental results on many problems have verified the effectiveness of SCA on some engineering application.

关键词： clustering feature extraction similar component.

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Fracture analysis of a functionally graded interfacial zone between two dissimilar homogeneous materials

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Science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 540-552页

作者： CHENG Zhanqi1,2.& ZHONG Zheng1 1. School of Aerospace Engineering and Applied mechanics, Tongji University, Shanghai 2.0092. china 2. College of Civil Engineering, Zhengzhou University, Zhengzhou 450002. china School of Aerospace Engineering and Applied mechanics Tongji University Shanghai China College of Civil Engineering Zhengzhou University Zhengzhou China

In this paper the plane elasticity problem for a functionally graded interfacial zone containing a crack between two dissimilar homogeneous materials has been considered. It is assumed that in the interfacial zone the reciprocal of the shear modulus is a linear function of the coordinate, while Possion’s ratio keeps constant. By utilizing the Fourier transformation technique and the transfer matrix method, the mixed boundary problem is reduced to a system of singular integral equations that are solved numerically. The influences of the geometric parameters and the graded parameter on the stress intensity factors are investigated. The numerical results show that the graded parameters, the thickness of interfacial zone, the crack size and location have significant effects on the stress intensity factors.

关键词： functionally graded material interfacial zone fracture stress intensity factor

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Resistance of Si_2._2. ceramics to oxidation and erosion of molten silica

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中国有色金属学会会刊：英文版 2000年第3期10卷 418-420页

作者： WANG Si qing(王思青) 1, YAN Yu hua(阎玉华) 2.1. Department of materials Engineering and Applied Chemistry, National University of Defense Technology, Changsha 410073, P.R.china 2. Biomaterials Engineering center, Wuhan University of Technology, W 国防科技大学湖南长沙武汉工业大学湖北武汉

Si 2. 2. ceramics was fabricated from powder by hot pressing in N 2.atmosphere. The resistance of the ceramic sample to oxidation and erosion of molten silica was investigated. The bulk density and open porosity of the ceramic sample were measured according to the Archimedes principle in water. Then fracture surface of the sintered body was observed by SEM. The results and analysis indicate that the resistance of Si 2. 2. ceramics to oxidation and erosion of molten silica increases when its density increases and/or its open porosity decreases. Moreover, they also reveal that the oxidation process is an unsteady dispersing process with oxygen as the constant source, and the resistance to erosion of molten silica related to the quantity of grain boundary in unit surface area. The lowest mass gain is 2.4 g/m 2.after oxidizing at 1 000 ℃ for 100 h in air, while the lowest mass loss is 2.9 g/m 2.after 40 h erosion in molten silica.

关键词： silicon oxynitride ceramics chemical stability

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Microstructure and formation mechanism of twins of laths of austenite with high nitrogen

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Science china(Technological Sciences) 2007年第6期50卷 755-764页

作者： WU CuiLan1,2.& LUO ChengPing2.1 center for High Resolution Electron Microscopy, College of materials Science and Engineering, Hunan University, Changsha 410082.{2. 2.College of Mechanical Engineering, South{2. University of Technology, Guangzhou 510641,{2. center for High Resolution Electron Microscopy College of Materials Science and Engineering Hunan University Changsha China College of Mechanical Engineering South China University of Technology Guangzhou China

The microstructure of composite diffusion layer of the nitrided and chromized 0.2. carbon steel is investigated using TEM and EDS. It is found that laths of austenite with high nitrogen (γ N) precipitate from α-ferrite matrix in the deeper zone of the diffusion layer. These γ N laths are all twins, with their {111} twinning planes parallel to the lath axis, thus forming a characteristic "back-to-back" morphology. There are two types of γN lath. The first is a genuinely {111} twin, and γ N and α keep the accurate K-S relationship, and each γ N and α form a sharp and smooth γ N/α inter- face of {335}γN//{341}α, namely habit plane {335}fcc. The second is a pseudo-twin, with micro-twins {111} or faults formed within the two twin components. Localized lattice deformation (relaxation) seems to have occurred at the interfaces of the second type of γ N due to the formation of micro-twins or faults within the twin components. These micro-twins or faults make the orientation relationship (OR) between each of the γN and the α-matrix deviate from the accurate K-S OR, and the OR between two γ N twin components deviate from the genuine {111} twin relation- ship. In addition, the γ N/α interface of the second type of γ N is not as sharp or smooth as that of the first one.

关键词： austenite containing nitrogen, twins, steel 2., nitriding, composite chromizing

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Game model of safety monitoring for arch dam deformation

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Science china(Technological Sciences) 2008年第S2期51卷 76-81页

作者： SU HuaiZhi1,2.WU ZhongRu1,2.GU YanChang1,2.HU Jiang1 & WEN ZhiPing3 1 College of Water Conservancy and Hydropower Engineering,Hohai University,nanjing 2.0098,china 2.National Engineering Research {2. of Water Resources Efficient Utilization and Engineering Safety,nanjing 2.0098,china 3 Department of Computer Engineering,nanjing Institute of Technology,nanjing 2.0013,china College of Water Conservancy and Hydropower Engineering Hohai University Nanjing China National Engineering Research center of Water Resources Efficient Utilization and Engineering Safety Nanjing China Department of Computer Engineering Nanjing Institute of Technology Nanjing China

Arch dam deformation is comprehensively affected by water pressure,temperature,dam's structural behavior and material properties as well as other *** them the water pressure and temperature are external factors(source factors) that cause dam deformation,and dam's structural behavior and material properties are the internal factors of deformation(resistance factors).The dam deformation is the result of the mutual game playing between source factors and resistance ***,resistance factors of structure and materials that reflect resistance character of arch dam structure are introduced into the traditional model,where structure factor is embodied by the flexibility coefficient of dam body and the maximum dam height,and material property is embodied by the elastic modulus of *** the basis of analyzing the correlation between dam deformation and resistance factors,the game model of safety monitoring for arch dam deformation is put forward.

关键词： arch dam deformation monitoring model flexibility coefficient game theory

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Thermal-stress Simulation of Direct-chill Casting of AZ31 Magnesium Alloy Billets

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Journal of Wuhan University of Technology(materials Science) 2009年第3期24卷 376-382页

作者：胡红军 College of materials Science and Engineering Chongqing University National Engineering Research center for Magnesium Alloys Chongqing University College of Material Science and Engineering Chongqing University of Technology

Two-dimensional （2.） transient coupled finite element model was developed to compute the temperature and stress field in cast billets, so as to predict the defects of the I-type billets made from AZ31 magnesium alloy and find the causes and solutions for surface cracks and shrinkages during direct-chill （DC） casting process. Method of equivalent specific heat was used in the heat conduction equation. The boundary and initial conditions used for primary and secondary cooling were elucidated on the basis of the heat transfer during the solidification of the billet. The temperature and the thermal-stress fields were simulated with the thermal-structural coupled module of ANSYS software. The influences of casting parameters on the distributions of temperature and stress were studied, which helped optimize the parameters （at pouring temperature of 680 ℃, casting speed of 2.min/s, heat-transfer coefficient of the second cooling equals to 5 000 W/m^2.℃^-1）. The simulation results of thermal stress and strain fields reveal the formation mechanism of some casting defects, which is favourable for optimizing the casting parameters and obtain high quality billets. Some measures of controlling processes were taken to prevent the defects for direct-chill casting billets.

关键词： magnesium alloy direct-chill casting temperature and stress fields numerical simulation solidification model

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