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journal of Computational Mathematics 1996年第4期14卷 363-382页

作者： x.j. Yu(Laborutory of Computational physics, Institute of applied physics and ComputationalMathematics, Beijing, China) INST APPL PHYS & COMPUTAT MATH LAB COMPUTAT PHYSBEIJINGPEOPLES R CHINA

The multigrid algorithm in [13] is developed for solving nonlinear parabolic equations arising from the finite element discretization. The computational cost of the algorithm is approximate O(NkN) where N-k is the dim... 详细信息

关键词： Th Math A MULTIGRID METHOD FOR NONLINEAR PARABOLIC PROBLEMS UC

Reflections on the Mechanism of Calcium Phosphate Nucleation on Titanium in Simulated Body Fluids

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journal of Materials Science & Technology 2005年第5期21卷 613-617页

作者： F.T.ChengDepartment of applied physics, The Hong Kong Polytechnic University, Hong Kong, China Department of applied physics Hong Kong Polytechnic University Hong Kong Hong Kong

The results and main findings of studies reported in the literature in relation to the deposition of calcium phosphate on Ti in simulated body fluids are summarized. The effects of the surface hydroxyl groups and the sign of surface charge on the nucleation of calcium phosphate are reviewed. One major controversy among the conclusions of different studies is the order of adsorption of the calcium ions and the phosphate ions in the initial stage of immersion. A simple model based on the amphoteric nature of the hydroxyl groups on Ti is proposed in an attempt to delineate the nucleation process for calcium phosphate on Ti in simulated body fluids. HPO4^2- ions interact with the hydroxyl groups via ion exchange and/or electrostatic attraction, and Ca^2＋ ions, via electrostatic attraction only. There is no preferential order of adsorption. Seemingly inconsistent results in different studies possibly arise from different prior treatments of the samples, which affect the adsorption properties.

关键词： Titanium Calcium phosphate Simulated body fluid Hydroxyl group Point of zero charge Surface charge

Ab initio study of a Y-doped Σ31 grain boundary in alumina

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Science China(physics,Mechanics & Astronomy) 2008年第11期51卷 1607-1615页

作者： CHEN jun, XU Yun, CHEN DongQuan & ZHANG jingLin Laboratory of Computational physics, Institute of applied physics and Computational Mathematics, Beijing 100088, China 1. Laboratory of Computational physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China

The atomic structures and energetics of clean and Y-doped general grain boundary (GB) Σ31/(0001) models in α-Al2O3 are studied by a series of high precision ab initio calculations. A large supercell with 700 atoms and periodic boundary conditions is adopted for undoped and Y-doped GB with different substitution sites and con-centrations. It is shown that Y atoms preferably segregate to the central column of the 7-member Al ring. This is explained as more favorable bond formation for Y in this position and lower GB energy. The calculated GB formation energy for the clean and Y-doped cases is respectively 3.99 and 3.67 j/m2. On the average, the GB region in Σ31 has a slightly lower charge density than the bulk crystalline region. In addtition, the GB induces a long ranged asymmetric electrostatic potential distri-bution on each side of the grain boundary.

关键词： alumina grain boundary Y-doped ab initio

A LAX-WENDROFF TYPE SCHEME WITH PREDICTOR-CORRECTOR

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计算物理 1991年第1期 95-101页

作者： Xu Guorong(Institute of applied physics and Computational Mathematics. Beijing)

In this paper a Lax- Wendroff type scheme with predictor-corrector is presented for solving the hyperbolic equations of fluid flow. The predictor solutions without introducing nonphysical oscillation are obtained by the method of flux vector splitting. The numerical flux of the corrector step is an anti - diffusive term, on which contraints are imposed to decrease the oscillation. Numerical experiments are presented to illustrate the performance of our proposed scheme.

关键词： A LAX-WENDROFF TYPE SCHEME WITH PREDICTOR-CORRECTOR 一刁二川

Microstructural Evolution of Rapidly Solidified Co-Mo and Ni-Mo Eutectic Alloys

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journal of Materials Science & Technology 2003年第6期19卷 553-556页

作者： Xiujun HAN, Wenjing YAO and Bingbo WEDepartment of applied physics, Northwestern Polytechnical University, Xi’an 710072, China Dept. of Appl. Phys. Northwestern Polytech. Univ. Xi'an 710072 China

Droplets of Co-37.6 wt pct Mo and Ni-47.7 wt pct Mo eutectic alloys were rapidly solidified during containerless processing in a 3 m drop tube. A kind of anomalous eutectic appears in these two eutectic alloys when undercooling is beyond 56 and 61 K, respectively. The two eutectic phases in anomalous eutectic were observed to grow in dendrite manner. The formation of anomalous eutectic is ascribed to the cooperative dendrite growth of the two independently nucleated eutectic phases. Current dendrite and eutectic growth theories are applied to describe the observed processes.

关键词： Rapid solidification Eutectic growth Dendrite growth Containerless processing

MELTING CRYSTALLIZATION BEHAVIOR OF NYLON 66

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Chinese journal of Polymer Science 2001年第3期19卷 237-246页

作者： Qing-xin Zhang Zhi-shen Mo State Key Laboratory of Polymer physics & Chemistry Changchun Institute of applied Chemistry Chinese Academy of Sciences, Changchun 130022, China Chinese Acad Sci Changchun Inst Appl Chem State Key Lab Polymer Phys & Chem Changchun 130022 Peoples R China

Analysis of isothermal and nonisothermal crystallization kinetics of nylon 66 was carried out using differential scanning calorimetry (DSC). The commonly used Avrami equation and that modified by jeziorny were used, respectively, to fit the primary stage of isothermal and nonisothermal crystallizations of nylon 66. In the isothermal crystallization process, mechanisms of spherulitic nucleation and growth were discussed. The lateral and folding surface free energies determined from the Lauritzen-Hoffman treatment are sigma = 9.77 erg/cm(2) and sigma (e) = 155.48 erg/cm(2), respectively; and the work of chain folding is q = 33.14 kj/mol. The nonisothermal crystallization kinetics of nylon 66 was analyzed by using the Mo method combined with the Avrami and Ozawa equations. The average Avrami exponent (n) over bar was determined to be 3.45. The activation energies (DeltaE) were determined to be -485.45 kj/mol and -331.27 kj/mol, respectively, for the isothermal and nonisothermal crystallization processes by the Arrhenius and the Kissinger methods.

关键词： nylon 66 crystallization kinetics activation energy

A Self-consistent Calculation and an Anisotropic Wavelength Cut off Energy of Spin-wave Spectrumin Magnetic Tunnel junctions

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journal of Materials Science & Technology 2001年第2期17卷 197-202页

作者： Xiufeng HAN State Key Laboratory of Magnetism, Institute of physics, Chinese Academy of Sciences, Beijing 100080, China Terunobu Miyazaki Department of applied physics, Graduate School of Engineering, Tohoku University, Aoba-yama 08, Sendai 980-8579, japa Chinese Acad Sci Inst Phys State Key Lab Magnetism Beijing 100080 Peoples R China Tohoku Univ Grad Sch Engn Dept Appl Phys Sendai Miyagi 9808579 Japan

Temperature dependence of tunnel magnetoresistance (TMR) ratio, resistance, and coercivity from 4.2 K to room temperature (RT), applied de bias voltage dependence of the TMR ratio and resistances at 4.2 K and RT, tunnel current I and dynamic conductance dI/dV as functions of the de bias voltage at 4.2 K, and inelastic electron tunneling (IET) spectroscopy, d(2)I/dV(2) versus V, at 4.2 K for a tunnel junction of Ta(5 nm)/Ni79Fe21(25 nm)/Ir22Mn78(12 nm)/Co75Fe25(4 nm)/Al(0.8 nm)-oxide/Co75Fe25(4 nm)/Ni79Fe21(25 nm)/Ta(5 nm) were systematically investigated. High TMR ratio of 59.2% at 4.2 K and 41.3% at RT were observed for this junction after annealing at 275 degreesC for an hour. The temperature dependence of TMR ratio and resistances from 4.2 to 300 K at 1.0 mV bias and the de bias voltage dependence of TMR ratio at 4.2 K from 0 to 80 mV can be evaluated by a comparison of self-consistent calculations with the experimental data based on the magnon-assisted inelastic excitation model and theory. An anisotropic wavelength cutoff energy of spin-wave spectrum in magnetic tunnel junctions (MTjs) was suggested, which is necessary for self-consistent calculations, based on a series of IET spectra observed in the MTjs.

关键词： off TMR A Self-consistent Calculation and an Anisotropic Wavelength Cut Energy of Spin-wave Spectrumin Magnetic Tunnel junctions wave Figure than

Luminescence of RE^(3+) and energy transfer from Gd^(3+) to RE^(3+) (RE = Dy, Eu) in SrGdAlO_4:RE^(3+)

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Chinese journal of Chemistry 1997年第1期15卷 60-67页

作者： LIU, Sheng-Li SU, QiangLaboratory of Rare Earth Chemistry and physics, Changchun Institute of applied Chemistry, Chinese Academy of Sciences, Changchun, jilin 130022, China Laboratory of Rare Earth Chemistry and physics Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun Jilin 130022 China [*]Laboratory of Rare Earth Chemistry and physics Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun Jilin 130022 China

Spectral properties of Gd3+, Dy3+ and Eu3+ ions in SrGdAlO4 are reported in detail. A cooperative vibronic transition of Gd3+ and the emission from the higher 5Dj (j=1, 2, 3) levels of Eu3+ were observed. Energy transfer occurs from Gd3+ to Dy3+ and to Eu3+. The influence of Gd3+ and Dy3+ concentrations on the luminescence intensity is discussed.

关键词： Luminescence energy transfer rare earth aluminate

Optical Properties of High Sensitivity Fiber Bragg Grating on Temperature Sensor

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光学学报 2003年第S1期23卷 843-844页

作者： Li Wang Shiya He Department of applied physics, Beijing University of Technology, Beijing 100022, China Department of applied physics Beijing University of Technology Beijing 100022 China

In this paper, the spectrum shift properties of the center reflection wavelength detected to be based on the FBG sensor with ambient temperature change. The basic theoretical methods and numerical simulation for the spectral properties of uniform Bragg grating is analyzed by using coupling mode theory which is optical properties of high sensitivity fiber Bragg grating on temperature sensor in accordance with experiment.

关键词： of in be et for FBG Optical Properties of High Sensitivity Fiber Bragg Grating on Temperature Sensor on