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Numerical Simulation of Unidirectional Infiltration of Silicon Carbide Preforms

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Journal of Materials science & technology 2001年第1期17卷 11-12页

作者： XueXi ZHANG Dezun WANG Dongyan DING and Congkai YAO school of Materials science and Engineering, harbin institute of technology, harbin 150001, china Sch. of Mater. Sci. Harbin Inst. of Technol. Harbin 150001 China

Mathematical model of unidirectional infiltration was set up and metal infiltration velocity and temperature fields of the metal, preform, and composites were calculated using the finite difference method. The metal infiltration velocity has a close relationship with infiltration time. It is very large after the infiltration begins in a few seconds, then the velocity keeps almost constant. The temperature field of the composite proves that metal matrix composites (M MCs) after unidirectional pressure infiltration can solidify from the entrance of the preform to the infiltration front, which is useful for obtaining the MMCS with low porosity and high properties.

关键词： FIBROUS PREFORMS PURE METAL

Study on Multi-enterprise Collaborative Resource Planning Based Process-oriented Decision Model

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武汉理工大学学报 2006年第S2期28卷 600-606页

作者： SHI Jinhua~1 HE Yingying~2 LIU Jianmin~3 1.school of Management,harbin institute of technology,harbin 150001,china 2.weihai Nongyou Software Company,weihai 264209,china 3.weihai High-tech Pioneering Service Center,weihai 264209,china school of Management Harbin Institute of TechnologyHarbin 150001China weihai Nongyou Software Company Weihai 264209China weihai High-tech Pioneering Service Center Weihai 264209China

Aiming to share the information,knowledge and optimizing resource via collaborating with multiple external partners across their supply chains,the concept model and system framework of multi-enterprises collaborative resource planning (MECORP) are put *** there is Considerable pressure to improve the operation of MECORP system,their inherent complexity can make modelling a MECORP system a difficult *** there could be considerable benefits in designing MECORP taking into account the operation of the *** order to address the central research issue of developing of a methodology that can assist a manager in making decisions by modelling the operation of MECORP *** methodology called process-oriented deci- sion model (PODM) is presented in the *** uses an abstracted network to model MECORP *** MECORP system supported by PODM,can effective optimize the manifold resource,coordinate the relationship of multiple partners and assist deci- ***,an industry excample of MECORP system is described to illustrate the application of PODM.

关键词： collaboration decision multi-enterprises operation process resource planning

Synthesis and characterization of ZnO nanostructures prepared by a thermal evaporation process

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Rare Metals 2007年第S1期26卷 153-156页

作者： CAI Wei,and LIU Wencheng school of Materials science and Engineering,harbin institute of technology,harbin 150001,china harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China

A series of ZnO nanostructures such as nanowires,nanobelts,nanocombs and mesoporous nanoballs were fabricated by a simple carbon reduction method without *** morphologies and microstructures of all samples were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and energy dispersive X-ray *** results indicate that different deposition temperatures have great impact on different shapes of ZnO *** growth mechanisms of these ZnO nanostructrues suggest that,by controlling the experiment parameters,different morphological configurations nanostructures can be fabricated.

关键词： ZnO nanostructures thermal evaporation nanowires vapor deposition

Microstructure and mechanical properties of extruded AZ31 magnesium alloy sheet

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Rare Metals 2007年第S1期26卷 226-230页

作者： WANG Xin,and FENG Jicai school of Materials science and Engineering,harbin institute of technology,harbin 150001,china harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China

The effects of billet temperature on the maximum punch load,microstructure and mechanical properties of the extrusion of AZ31 cast magnesium alloy were *** is found that with the temperature decreasing,the microstructure of extruded sheets is more homogeneous and the grains become *** grain refinement does little effect on the strength of the material but significantly affects the *** the billet temperature is kept constant at room temperature,the elongation of the billets is up to 23%.The mechanical properties at extrusion direction(ED) and transverse direction(TD) were also *** differences of the properties between ED and TD are not obvious.

关键词： AZ31 magnesium alloy extrusion dynamic recrystallization

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咖啡因的科学共识

中国食品学报 2024年第6期24卷 498-504页

作者：中国食品科学技术学会北京100048

咖啡因是一种常见于咖啡、茶叶和可可等植物中的天然活性成分,作为功能添加成分已在国际食品领域广泛应用多年,适量摄入有助于健康人群提高注意力,促进运动能力,缓解疲劳。国内外相关食品安全监管机构一致认为,咖啡因虽在日常饮食中的... 详细信息

咖啡因是一种常见于咖啡、茶叶和可可等植物中的天然活性成分,作为功能添加成分已在国际食品领域广泛应用多年,适量摄入有助于健康人群提高注意力,促进运动能力,缓解疲劳。国内外相关食品安全监管机构一致认为,咖啡因虽在日常饮食中的摄入是安全的,但需关注个体差异、摄入量以及频率。许多国家和地区已对咖啡因在食品中的应用制定了严格的应用限量和标识规定。为进一步提升大众对咖啡因的科学认知,消除对咖啡因的偏见,推动咖啡因在相关食品产业的合理应用,中国食品科学技术学会组织食品科学、公共卫生、食品安全与食品营养等领域专家与相关产业界代表,通过现场咨询、文献检索、专题研讨等形式和方法,经广泛讨论形成咖啡因的科学共识,以推动咖啡因在我国的规范使用。

关键词：咖啡因健康益处摄入量应用管理

Hot compressive deformation behaviors and micro-mechanisms of TA15 alloy

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Rare Metals 2007年第S1期26卷 162-167页

作者： LIU Yong,ZHU Jingchuan,WANG Yang,and ZHAN Jiajun school of Materials science and technology,harbin institute of technology,harbin 150001,china harbin Inst Technol Sch Mat Sci & Technol Harbin 150001 Peoples R China

The hot deformation behaviors of TA15 alloy,as well as the microstructure obtained after compressive deformation,were *** results show that TA15 alloy exhibits a peak stress when deformed at temperature lower than 900 ℃,implying recrystallization ***,steady flow stress-stain behavior is observed without peak stress when deformation is employed at temperature higher than 900 ℃,showing recovery ***-deformation band appears at deformation temperature of 750 ℃,and equiaxed grains are found at 800 ℃,implying the occurrence of *** deformed at 925 ℃,the specimen shows the recovery characteristics with dislocation networks and sub-grain boundaries.

关键词： TA15 alloy hot compressive deformation micro-mechanisms

First principles study on effect of lanthanum on nitrogen diffusion in ε-Fe_3N phase

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Rare Metals 2007年第S1期26卷 251-254页

作者： WU Yeqiong,and YAN Mufu school of Materials science and Engineering,harbin institute of technology,harbin 150001,china harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China

The effect of lanthanum(La) on nitrogen atom diffusion in ε-Fe3N phase produced during nitriding with and without rare earth addition were studied based on the density function theory of first principles and the quantum mechanics program CASTEP code of Material Studio *** results show that the presence of La in ε-Fe3N phase can lead to the shrinks of a and b axis and the elongation of c axis of ε-Fe3N crystal *** total energy and the stability of the crystal cell with La are lower and higher than that without La,*** activation energy of nitrogen atom in ε-Fe3N phase with La is 1.01 eV smaller than that in ε-Fe3N phase without *** is the main reason why rare earth elements diffusing into compound layer produced during nitriding can accelerate the nitriding process or shorten the nitriding duration.

关键词： first principles lanthanum nitrogen diffusion ε-Fe_3N phase

MICROSTRUCTURE，INTERFACE　AND　MECHANICAL　PROPERTIES　OF　NiAl－BASED　COMPOSITES　REINFORCED　BY　TiB_2　PARTICULATES

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Acta Metallurgica Sinica(English Letters) 1995年第Z1期8卷 455-465页

作者： GUO Jianting(institute of Metal Research, Chinese Academy of sciences, Shelving 110015, china)XING Zhanping(school of Materials science and Engineering, harbin institute of technology, harbin 150001, china) Inst of Metal Research Chinese Acad of Sciences Shenyang China

This paper developed a hot Pressing aided exothermic synthesis (HPES) technique. to fabricate NiAl matrix composites containing 0 and 20 v.% TiB_2 particles. The conversion to the product was complete. and TiB_2 particles in the matrix were uniformly dispersed. The inter faces between nail and TiB_2 were atomically flat. sharp and free from any inter facial phases in most cases. In some cases. however. thin inter facial amorphous layers existed at NiAl/ TiB_2 interfaces. In addition, the microstructure and inter faces were highly thermal stable. In all processing states. the yield strengths at room temperature or at 1000℃ of the composite were approximately three times as strong as that of the unrein forced NiAl. The ambient fracture toughness of the composite was also superior to monolithic NiAl.

关键词： intermatallic matrix composite NiAl-TiB_2 microstructure interface,mechanical property

Influence of polymer on shrinkage and anti-cracking performance of mortar

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Rare Metals 2007年第S1期26卷 120-123页

作者： LI Jiahe1),OU Jinping2),and WANG Zheng1)1) school of Material science and Engineering,harbin institute of technology,harbin 150001,china 2) school of Civil Engineering,harbin institute of technology,harbin 150001,china harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China harbin Inst Technol Sch Civil Engn Harbin 150001 Peoples R China

A self-designed restrained ring test was applied to investigate cracking of *** cracking total weigh W and cracking control rate K were applied to evaluate anti-cracking performance of *** the above method,the influence of polymer on the shrinkage and anti-cracking performance was *** microstructures of mortar specimens were investigated by means of *** results indicated that the addition of polymer can efficiently reduce the shrinkage of mortar and improve the anti-cracking performance of mortar.

关键词： mortar shrinkage cracking anti-cracking