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VISCO-PLASTIC CONSTITUTIVE MODEL FOR UNIAXIAL AND MULTIAXIAL RATCHETING AT ELEVATED TEMPERATURES

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 431-436页

作者： G.Z.Kang q.Gao j.Zhang Dept. of Applied Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 ChinaDept. of Applied Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 ChinaDept. of Applied Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China

Based on the experimental results of the ratcheting for SS304 stainless steel, a new visco-plastic cyclic constitutive model was established to describe the uniaxial and multiaxial ratcheting of the material at room and elevated temperatures within the framework of unified visco-plasticity. In the model, the temperature dependence of the ratcheting was emphasized, and the dynamic strain aging occurred in the temperature range of 4 00-600℃ for the material was taken into account particularly. Finally, the prediction capability of the developed model was checked by comparing to the corresponding experimental results.

关键词： constitutive model ratcheting elevated temperature multiaxial loading

STUDY ON STRUCTURES OF Al-CuAl_2 EUTECTIC SOLIDIFIED UNDER ELECTROMAGNETIC STIRRING

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Acta Metallurgica Sinica(English Letters) 1997年第6期10卷 461-464页

作者： W.q. Zhang q.M. Liu Y.F. zhu Y.S. Yang and Z.q. Hu(State Key Laboratory of RSA, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, China) Inst of Metal Research Chinese Acad of Sciences Shenyang China

An investigation on electromagnetically-stirred solidification of Al-CuAl2 eutectic system is presented in this paper. With electromagnetic stirring in solidification, structural transition from lamellar to rod-like eutectic has been found in the as-cast structures, and provided strong stirring is applied, proeutectic growth of α-Al phase is enhanced. Moreover, the interphase spacing of eutectic is clearly increased with melt flow intensified. Numerical computation of flow field is also presented, and the effect of stirring on structural formation is discussed.

关键词： electromagnetic stirring eutectic,interphase spacing fluid flow

Gradient microstructure,recrystallization and mechanical properties of copper processed by high pressure surface rolling

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journal of Materials Science & Technology 2022年第31期126卷 182-190页

作者： j.Guo q.Y.He q.S.Mei X.Huang G.L.Wu O.V.Mishin College of Materials Science and Engineering Chongqing UniversityChongqing400045China Southwest Technology and Engineering Research Institute Chongqing 400039China School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Department of Mechanical Engineering Technical University of Denmark2800 Kgs.LyngbyDenmark

The microstructure,hardness and tensile properties have been studied in copper processed by high pressure surface rolling(HPSR)both in the as-deformed condition and after subsequent annealing at 150℃.It is found that a gradient structure with significant differences in the scale of microstructural features is formed by *** deformed microstructure varies from nano-and ultrafine-scale structures with a large fraction of high angle boundaries near the surface to lightly deformed grains at depths of 1-3 mm below the *** tests of 1-mm-thick specimens demonstrate that the asdeformed material has a high strength and a low uniform *** at 150℃results in partial recrystallization,which creates new through-thickness *** for the topmost layer and several bands in the adjacent layer,recrystallization is more pronounced close to the *** fraction recrystallized is at least 80%at depths of 60-300μm after annealing for 960 *** fraction recrystallized in the subsurface decreases with increasing depth,and the deformed layer at depths greater than 500μm re-mains largely non-recrystallized after *** partially recrystallized condition demonstrates an improved combination of strength and ductility.

关键词： High pressure surface rolling Copper Gradient microstructure Annealing Hardness Strength Ductility

High-resolution dipole ( e, e ) study for optical oscillator strengths of valence shell excitation of nitrogen

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Chinese Science Bulletin 1997年第17期42卷 1426-1429页

作者： Zhang, Xj Feng, RF Zhong, ZP ji, q zhu, LF Wu, SL Xu, KZ Department of Modern Physics University of Science and Technology of China Hefei China

NITROGEN is the most abundant element in the earth’s atmosphere. The study of optical oscillator strengths of nitrogen is of great significance in atmosphere physics, space physics and environment science. These results are also used in many fields, such as fusion plasma and developments of the nitrogen laser. As we know, calculation of absolute optical oscillator strengths of molecular nitrogen are still at the level of electronic rather than vibronic states resolved.

关键词： nitrogen optical oscillator strength high-resolution dipole (e e) method electron energy-loss spectrum.

COUPLED SIMULATION OF 3D ELECTRO-MAGNETO-FLOW FIELD IN HALL-HEROULT CELLS USING FINITE ELEMENT METHOD

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Acta Metallurgica Sinica(English Letters) 2006年第2期19卷 105-116页

作者： j. Li W. Liu Y.q. Lai q.Y. Li Y.X. Liu School of Metallurgy Science and Engineering Central South University Changsha 410083 China Chemistry Department Guangxi Normal University Guilin 531400 China

Two full 3D steady mathematical models are developed by finite element method （FEM） to calcalate coupled physics fields. the electro-magnetic model is built and solved first and so is the fluid motion model with the acquired electromagnetic force as source body forces in Navier-Stokes equations. Effects caused by the ferromagnetic shell, busbar system around, and open boundary problem as well as inside induced current were considered in terms of the magnetic field. Furthermore, a new modeling method is found to set up solid models and then mesh them entirely with so-called structuralized grids, namely hex-mesh. Examples of 75kA prebaked cell with two kinds of busbar arrangements are presented. Results agree with those disclosed in the literature and confirm that the coupled simulation is valid. It is also concluded that the usage of these models facilitates the consistent analysis of the electric field to magnetic field and then flow motion to the greater extent, local distributions of current density and magnetic flux density are very much dependent on the cell structure, the steel shell is a shield to reduce the magnetic field and flow pattern is two dimensional in the main body of the metal pad.

关键词： coupled simulation electromagnetic field flow field aluminum reduction cell finite element analysis

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基于视频游戏的空间能力测评

心理科学进展 2025年第1期33卷 11-24页

作者：尚俊杰石祝沈科杰北京大学教育学院学习科学实验室北京100871

空间能力是个体对客体或空间图形在头脑中进行识别、编码、贮存、表征、分解组合和抽象概括的能力,是个体理解自身所处环境并解决问题的认知基础。准确、便捷、有效地测评空间能力,对增强STEM教育教学水平和人才培养质量都具有重要意义... 详细信息

空间能力是个体对客体或空间图形在头脑中进行识别、编码、贮存、表征、分解组合和抽象概括的能力,是个体理解自身所处环境并解决问题的认知基础。准确、便捷、有效地测评空间能力,对增强STEM教育教学水平和人才培养质量都具有重要意义。由于空间能力受多因素共同作用,具有复杂性、多维度、内隐性的特点,使得利用计算机评价空间能力比较困难。本研究旨在准确、有效、大规模地测评空间能力,将使用多模态学习分析方法探索学习者空间认知行为表现特征,并基于视频游戏环境研发空间能力隐形测评关键技术与工具。具体包括:1)构建空间能力内在表征框架和评价指标体系;2)基于多模态学习分析构建学习者空间能力行为表现模型;3)探索视频游戏影响空间能力的关键因素,并使用游戏引擎开发基于视频游戏的测评工具;4)使用以证据为中心的设计框架和贝叶斯网络模型,开发并部署能够推断和预测空间能力的测评算法;5)在实验室和真实课堂情境开展实证研究,验证测评工具有效性。研究成果将有利于理解人类空间认知过程和行为表现,拓展和丰富空间能力相关理论,并为大规模数字化测评提供关键技术支撑。

关键词：基于游戏的测评空间能力多模态学习分析游戏化学习隐形测评

ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY DURING CORROSION PROCESS OF 8090 Al-Li ALLOY IN EXCO SOLUTION

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 894-901页

作者： j.F.Li Z.q.Zheng C.Y.Tan S.C.Li Z.Zhang j.q.Zhang CollegeofMaterialsScienceandEngineering CentralSouthUniversityChangsha410083China／／DepartmentofChemistryZhejiangUniversityHangzhou310027China CollegeofMaterialsScienceandEngineering CentralSouthUniversityChangsha410083China DepartmentofChemistry ZhejiangUniversityHangzhou310027China DepartmentofChemistry ZhejiangUniversityHangzhou310027China／／StateKeyLaboratoryforCorrosionand.ProtectionInstituteofMetalResearchTheChineseAcademy

The corrosion behavior and electrochemical impedance spectroscopy (EIS) features of 8090 Al-Li alloys in EXCO solution were investigated, and the EIS was simulated using an equivalent circuit. At the beginning of immersion in EXCO solution, the EIS is comprised by a depressed capacitive arc at high-mediate frequency and an inductive arc at low frequency, and the inductive component decreases and disappears with im- mersion time. Once exfoliation or severe pitting corrosion is produced, two capacitive arcs appear in the EIS. These two capacitive arcs are originated from the two parts of the corroded alloy surface, the original flat alloy surface and the new inter-face exposed to the aggressive EXCO solution due to the exfoliation or pitting corrosion. Some corrosion development features of 8090 Al-Li alloys in EXCO solution can be obtained through simulated EIS information.

关键词： Al-Li alloy, exfoliation, electrochemical impedance spectros- copy (EIS), EXCO solution

PARTICLE SIZE AND MICROSTRUCTURE OF Ni NANOPOWDERS PREPARED BY ANODIC ARC PLASMA

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 209-216页

作者： Z.q.Wei H.X.qiao j.F.Dai W.j.Feng q.Wang P.X.Yan SchoolofSciences LanzhouUniversityofTechnologyLanzhou730050China CollegeofCivilEngineering LanzhouUniversityofTechnologyLanzhou730050China SchoolofPhysicalScienceandTechnology LanzhouUniversityLanzhou730000China

Pure Ni nanopowders were successfully prepared by the method of anodic arc disch arged plasma with homemade experimental apparatus. The particle size, mircostruc ture and morphology of the particles by this process were characterized via X-ra y powder diffraction (XRD), transmission electron microscopy (TEM) and the corre sponding selected area electron diffraction (SAED); The specific surface area an d pore parameters were investigated by multi-point full analysis of nitrogen ads orption-desorption isotherms at 77K by Brunauer- Emmett-Teller (BET) surface are a analyzer; The chemical composition were determined by X-ray energy dispersive spectrometry (XEDS) equipped in SEM and element analyze instrument. The experime nt results indicate that the samples by this method with high purity,the crystal structure of the particles is as same as the bulk material, is fcc structure, w ith average particle sizes about 47nm, ranging from 20 to 70nm, and distributed uniformly in spherical chain shapes, the specific surface areavis 14.23m2/g, po re volume of pore is 0.09cm3/g and average pore diameter is 23nm.

关键词： anodic arc plasma Ni nanopowder particle size structure composition.

High response and selectivity methanol gas sensor using molecular imprinting technique

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High response and selectivity methanol gas sensor using mole...