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Fabrication of Ni_3Al by hot pressing from element powders

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Rare Metals 2007年第3期26卷 222-225页

作者： MENG Jie JIA Chengchang HE Qing School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Ni3Al intermetaUic was synthesized by hot pressing from element powders of nickel, aluminum, and boron. The influences of parameters on the properties of Ni3Al were investigated. The parameters include the particle size of nickel powder, adding or without boron powder, hot pressing temperature, etc. The properties include the density of hot-pressed samples, resultant redo of Ni3A1.phase, and bending strength. The microstructures of hot-pressed samples were investigated by X-ray diffraction and scan electronic microscopy, and the properties, such as density and bending strength, were also measured. The results show that a higher bending strength was obtained under the same hot pressing conditions by the fine nickel powder than the coarse one, and there is little difference about density. Boron powder added in this process accelerates the formation of Ni3Al and markedly increases the hot pressed density. In the temperature range of this study, the density increases along with the hot pressing temperature. Full dense Ni3Al samples were obtained under the condition of 860℃, 1. min, 4. MPa from Ni-22.89A1.0.5B powder.

关键词： Ni3Al intermetallics powder technology hot pressing.

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Journal of Hydrodynamics 2000年第1期12卷 117-126页

作者： Xia, Liping Yang, Zhifeng Ming, Lamkit beijing Normal Univ Beijing China

The RNG k εturbulence model is adopted to investigate a turbulent round jet issuing into crossflow, with the Reynolds number at jet exit of Re=6000 and jet to crossflow velocity ratio of r=8. With the CFD code, FLUENT, the relations of dimensional analysis are successfully reproduced and the calculated coefficients agree well with the experimental measurements of Wong (1.91. and Chu (1.96). The investigations are then taken on the velocity, stream function and vorticity at the far field of the jet. It shows that at least within the covered range herein, the jet at the far field is self similar.

关键词： jet in crossflow RNG k ε turbulence model self similarity

The (⊿+2,2)-incidence coloring of outerplanar graphs

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Progress in Natural Science:Materials International 2008年第5期18卷 575-578页

作者： Shudong Wanga,b,c, Jin Xu a,b, Fangfang Mac, Chunxiang Xua,b a Institute of Software, School of Electronic Engineering and Computer Science, Peking university, {1. 1.0871. china b Key Laboratory of High Con dence Software Technologies, Ministry of Education, {1. 1.0871. china c College of Information Science and Engineering, Shandong university of Science and Technology, Qingdao 26651., china Institute of Software School of Electronic Engineering and Computer Science Peking University Beijing 100871 China Key Laboratory of High Confidence Software Technologies Ministry of Education Beijing 100871 China College of Information Science and Engineering Shandong University of Science and Technology Qingdao 266510 China

An incidence coloring of graph G is a coloring of its incidences in which neighborly incidences are assigned di erent colors. In this paper, the incidence coloring of outerplanar graphs is discussed using the techniques of exchanging colors and the double inductions from the aspect of con guration property. Results show that there exists a (D + 2,2)-incidence coloring in every outerplanar graph, where D is the maximum degree of outerplanar graph.

关键词： Incidence coloring Incidence chromatic number Outerplanar graph

GRID GENERATION OF COMPLEX PRACTICAL AIRCRAFT & ZONAL SOLUTION OF EULER EQUATIONS FOR HIGH-INCIDENCE VORTICAL FLOWS(HIVF)

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Chinese Journal of Aeronautics 1997年第3期10卷 2-8页

作者： Zhang Zhengke, Zhu Zhiqiang, Zhuang Fenggan (Institute of Fluid Mechanics, beijing {1. of Aeronautics and Astronautics, beijing, 1.0083, china)

A complete process of grid generation for complex practical aircraft is described with a twin tail fighter as an example. Euler equations are discretized in the generated multiblock grid by a finite volume method and solved by a three stage explicit time stepping scheme in each block with some extra treatments of interface at each step. The predicted aerodynamic coefficients and vortical flow field are reasonable.

关键词： fighter aircraft grid generation (mathematics) elliptic partial differential equations Euler equations zonal method

A first-principles investigation into the hydrogen bond interaction in β-HMX

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Science china(Physics,Mechanics & Astronomy) 2010年第6期53卷 1080-1085页

作者： CHEN Fang 1.,ZHANG Hong 1.2,ZHAO Feng 3 ,MENG ChuanMin 3 & CHENG XinLu 1.1.Institute of Atomic and Molecular Physics,Sichuan university,Chengdu 61.065,{1. 2 School of Physical Science and Technology,Sichuan university,Chengdu 61.065,{1. 3 Laboratory for Shock Wave and Detonation Physics Research,Southwest Institute of Fluid Physics,{1. Academy of Engineering Physics,Mianyang 621.00,{1. 1. Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China2. School of Physical Science and Technology Sichuan University Chengdu 610065 China3. Laboratory for Shock Wave and Detonation Physics Research Southwest Institute of Fluid Physics China Academy of Engineering Physics Mianyang 621900 China

A theoretical study of structural and electronic properties of β-HMX crystal is performed using density-functional theory(DFT). The total density of states(TDOS) is presented. The atomic orbit projected density of state(PDOS) from the p-type orbit of C,N,O and the s-type orbit of H is discussed. The study by analyzing the PDOS shows that the structure of β-HMX crystal possesses C-H···O intra- and inter-molecular hydrogen-bonding. There exists a hydrogen bonding between H5 -1. and O1. -2p orbits,between H1. -1. and O28 -2p orbits of intra molecules,and between H1. -1. and O24.-2p orbits of inter molecules. The Mulliken population analysis is also made.

关键词： structural property hydrogen bond β-HMX population analysis

Modeling of Mechanical Behavior of Fractal Rock Joint

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International Journal of Minerals,Metallurgy and Materials 1999年第3期13卷 157-164页

作者： Jinan bang Marek A. Kwasniewski( Resources Engineering School. university of Science and Technology {1., Bejing 1.0083, china)( Rock Mechanics Laboratory, Faculty of Mining and Geology, Technical university of Silesia, Gliwice , Poland) Resources Engineering School University of Science and Technology Beijing Beijing 100083 China Rock Mechanics Laboratory Faculty of Mining and Geology Technical University of Silesia Gliwice Poland

The present study shows that naturally developed fracture surfaces in rocks display the properties of self-affine fractals. Surface roughness can be quantitatively characterized by fractal dimension D and the intercept A on the log-log plot of variance: the former describes the irregularity and the later is statistically analogues to the slopes of asperities. In order to confirm the effects of these fractalparameters on the properties and mechanical behavior of rock joints, which have been observed in experiments under both normal andshear loadings, a theoretic model of rock joint is proposed on the basis of contact mechanics. The shape of asperity at contact is assumed to have a sinusoidal form in its representative scale r, with fractal dimension D and the intercept A. The model considers different local contact mechanisms, such as elastic deformation, frictional sliding and tensile fracture of the asperity. The empirical evolution law of surface damage developed in experiment is implemented into the model to up-date geometry of asperity in loading history. The effects of surface roughness characterized by D, A and re on normal and shear deformation of rock joint have been elaborated.

关键词： fractal roughness mechanical behavior rock joints fractal dimension the intercept contact mechanics normal stiffness shear stiffness, surface damage

Effect of Crystallinity on Electrochemical Insertion/Extraction of Li in Transition Metal Oxides Part I: LiMn_2O_4.and LiCo_(0.5)Ni_(0.5)O_2

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Journal of Materials Science & Technology 1999年第6期15卷 509-514页

作者： Tomoki TSUMURA and Michio INAGAKI (graduate School of Engineering, Hokkaido {1. Kita-ku, Sapporo, 060-8628 Japan) Hokkaido Univ Grad Sch Engn Kita Ku Sapporo Hokkaido 0608628 Japan

Electrochemical insertion/extraction of Li on cathode materials of spinel type LiMn2O4.and ordered rock-salt type LiCo0.5 Ni0.5O2 was measured on samples of which structures were well characterized. On the basis of experimental results on structure, morphology and charge-discharge characteristics, the effect of crystallinity of the cathode materiaIs on electrochemical Li insertion/extraction performance was discussed. These two transition metal oxides belong to onegroup that the crystallinity of these oxides affects to the performance.

关键词： LiMn2O4.and LiCo Effect of Crystallinity on Electrochemical Insertion/Extraction of Li in Transition Metal Oxides Part I O2 Ni

A new buprenorphine analogy, thenorphine, inhibits morphine-induced behavioral sensitization in mice

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Acta Pharmacologica Sinica 2004年第11期 29-34页

作者： Wen-li ZHAO, Ze-hui GONG, Jian-hui LIANGDepartment of Neuropharmacology, National Institute on Drug Dependence, Peking university, {1. 1.0083 {1. Institute of Pharmacology and Toxicology, {1. 1.0850,{4.

AIM: To investigate effects of thenorphine, a new compound of partial agonist of μ-opioid receptor, on the loco-motor activity and the behavioral sensitization to morphine in mice. METHODS: Locomotor activity was observed after administration of thenorphine or co-administration of thenorphine and morphine in mice. Mice were induced behavioral sensitization to morphine by intraperitoneal injection of 20 mg/kg morphine once daily for 7 d. Thenorphine was co-administrated with morphine to observe the effects of thenorphine on the development, transfer and expression of morphine-induced behavioral sensitization. RESULTS: A single dose of thenorphine (0.0625, 0.25, and 1.0 mg/kg) could dose-dependently inhibit the locomotor activity in mice (P1.. Co-adminis

关键词： thenorphine morphine behavioral sensitization mice

Mobile HTc SQUID MCG Measurement System

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Mobile HTc SQUID MCG Measurement System