Melting of xenon monolayers - computer simulations

The results of Monte Carlo simulations of xenon monolayers deposited on graphite are presented. Systems of various surface densities and in a wide range of temperatures are investigated. The results are compared to the experimental data and to the previous results for nitrogen. The results of simulations are in good agreement with the experimental ones and confirm that melting in two dimensions is vacancy-driven. Typical real-space configurations of Xe atoms and calculated specific heat results are shown.     

水位骤变时的饱和-不饱和渗流数值计算

本文应用全隐式交替方向迭代法对水位骤变时的饱和-不饱和渗流问题求出了数值解。对于赤井模型,计算结果与实验结果十分接近,比有限元法的计算结果好。对于大尺度的驹田蓄水池模型,计算结果与有限元法的结果基本一致。     

冲击压缩下NaCl单晶光辐射特性的研究

 用光辐射技术研究了氯化钠单晶冲击压缩下的光辐射特性,得到了在45～70 GPa压力范围内NaCl单晶的光谱吸收系数随冲击压力的变化,把这一结果与Kormer等人的结果比较,发现在较低压力下与Kormer等人的结果相差较少,当压力较高时实验结果比Kormer等人的结果约大1个数量级。并用实验结果计算了电子迁移率随冲击温度的变化,得到的结果与Ziman理论基本一致,从而解决了一直来Kormer的实验结果与Ziman理论不一致的困难,进一步证明了Ziman理论的正确性。     

抗爆容器内爆炸流场数值模拟

 采用计算流体动力学中的二阶精度TVD差分格式和特殊算子分裂法,按轴对称问题,对半球顶圆柱筒密闭式抗爆容器内部爆炸流场进行了数值模拟。计算得到的容器壁面载荷分布与实验结果基本一致。不同时刻爆炸流场压力分布图像清晰地描述了容器壁面的冲击波加载过程。     

Excited states of muonium in atomic hydrogen

Muonium formation in excited states in muon-hydrogen charge-exchange collision is investigated using a method developed in a previous paper. Differential cross-section results are found to resemble positronium formation cross-section results of positron—hydrogen charge-exchange problem. Forward differential and integrated cross-sections are computed for muon energy of 2 keV and higher. Total muonium formation cross-sections are computed using Jackson and Schiff scaling rules. Muonium formation cross-section results obtained from proton—hydrogen charge-exchange cross-section results, using velocity scaling are compared with the results of the present calculation     

Computation of triple differential cross-sections with the inclusion of exchange effects in atomic K-shell ionization by relativistic electrons for symmetric geometry

The triple differential cross-section for K-shell ionization of silver and copper atoms by relativistic electrons have been computed in the coplanar symmetric geometry with the inclusion of exchange effects following the multiple scattering theory of Das and Seal [1] multiplied by suitable spinors. Present computed results are marginally improved in some cases from the previous computed results [2]. Present results are compared with measured values [3] and with previous computation results [2]. Some other theoretical computational results are also presented here for comparison.      

Meson-Meson Scattering on Anisotropic Lattices

Using the tadpole improved Wilson quark action on small, coarse, and anisotropic lattices, meson-meson scattering lengths are calculated within quenched approximation. The study covers pion-pion scattering in the I=2 channel and kaon-pion scattering in the I=3/2 channel. The results are extrapolated towards the chiral limit. Finite volume and finite lattice spacing errors are also analyzed and results in the infinite volume and continuum limit are obtained. Our results are compared with the results obtained using Roy equations, chiral perturbation theory, dispersion relations, and the experimental data. We also compare our results with other lattice results on the scattering lengths.     

用质点源方法计算三维内电磁脉冲

本文给出用质点法求解三维长方腔体中的初级电流及其相应的内电磁脉冲的数值结果。井把这种方法得到的结果与三维欧拉方法的计算结果作了比较。在相同的计算条件下,两种方法得到的结果符合较好。     

Molecular dynamics study of self-diffusion in stoichiometric B2-NiAl crystals

Self-diffusion parameters in stoichiometric B2-NiAl solid state crystals were estimated by molecular statics/dynamics simulations with the study of required simulation time to stabilise diffusivity results. An extrapolation procedure to improve the diffusion simulation results was proposed. Calculations of volume diffusivity for the B2 type NiAl in the 1224–1699?K temperature range were performed using the embedded-atom-model potential. The results obtained here are in much better agreement with the experimental results than the theoretical estimates obtained with other methods.     

A practical comparison of surface resistance test electrodes

Four surface resistance test electrodes are compared using a selection of materials under similar test conditions. The results vary considerably with some materials due to variation in surface resistivity. Using a relatively uniform material two concentric ring electrodes compliant with the same standard differed in results by a factor of 1.8. Silver stripe and copper tape electrodes gave results a factor 0.4 and 0.7 compared to the reference electrode. A 2-pin electrode gave results a factor 4.7 greater. The 2 pin probe cannot be expected to give similar results to the other electrodes for materials that have variable resistivity.     

LO-phonon effect on the exciton binding energy in polar rectangular quantum wires

Longitudinal optical phonon effect on Wannier excitons in polar rectangular quantum wires is studied by a variational approach. The binding energy is calculated and the numerical results for several II-VI and III-V compound semiconductor rectangular quantum wires are given. The results show that the phonon effect reduces the binding energy and cannot be neglected. The phonon contribution to the binding energy is sensitive to the size of the rectangular quantum wire section, and increases with decreasing section area. The results for the GaAs rectangular quantum wires coincide with the experimental results. The calculated binding energy and the phonon effect in II-VI QWWs are both stronger than those in III-V compound systems, and the results for ZnSe QWW are qualitatively in agreement with the experiments.     

Analysis of the Scattering Characteristic of Several Waveguide Components Using Boundary Element Method

Several kinds of waveguide components such as curved waveguide bends, arbitrary angle waveguide bends and T-junctions have been analyzed with boundary element method in this paper. A new discretization method for the boundary element method to solve the waveguide discontinuities has been given. The numerical results obtained agree well with the experimental results and numerical results in other literature. Especially, the scattering characteristics of Forded E-, H-plane T-junctions in 3mm band have been analyzed using boundary element method and the calculation results are presented.     

水面目标复合电磁散射的并行迭代快速计算

采用快速远场近似的降秩电磁流迭代法计算目标与粗糙水面的复合散射, 并进一步采用粗糙面分区的多进程并行迭代算法提高其计算速度, 分析了降秩电磁流迭代法对散射结果的影响, 表明该方法可用于近场复合散射问题的计算; 对平板目标与水面间的复合散射进行了计算, 计算结果与快速多极子方法(MLFMM)结果符合较好, 验证了该算法的有效性. 同时, 利用造波水池开展了目标与水面近场复合散射的模拟实测, 测试与计算结果趋势较为一致.     

钬铝石榴石晶场参数调整

利用比热实验值,对钬铝石榴石（Ho3Al5O12）晶体的晶场参数进行了调整,依此计算了Ho3Al5O12晶体的晶场能谱、Zeeman劈裂能级和波函数. 在外磁场H=0时,分别计算了Ho3Al5O12晶体的总比热、总熵随温度的变化,以及外磁场H=10kOe时该晶体倒数磁化率的温度关系,理论计算结果均与已有实验数据符合较好.该工作为进一步探究该晶体的其它性质奠定了必要的理论基础,对实际生产和科学研究中磁制冷材料的优化选取也具有一定的现实意义.     

同轴型双程放大器的研究

理论上计算了在多程放大过程中反转粒子数的利用效率，反转粒数的分布等。计算结果与“神光－Ⅱ”主放大器原型－同轴型双程放大器－实验结果相符合。     

碳富勒烯在水中的运动阻力特性

采用分子动力学(MD)方法,模拟了Cn(n=60,180,240,540)以及C60@C240富勒烯在水中的速度衰减过程,得到了它们的阻力一速度与阻力,雷诺(Re)数关系曲线;进而将MD模拟的阻力结果和低Re数宏观流体力学中球的Stokes阻力解进行了对比,研究表明,低Re数下,富勒烯在水中的阻力要比传统流体力学中球的Stoke解高两个数量级;富勒烯在水中的阻力可通过Stokes解乘以(110.38-1.48/Re)近似估算.     

高效液相色谱法测定黄柏中盐酸小檗碱含量的不确定度评估

介绍一种高效液相色谱法测定含量的不确定度计算方法.通过黄柏中盐酸小檗碱含量测定结果,对产生不确定度的各分量进行计算,研究测量不确定度的主要分量,以控制检验环节的质量,保证结果准确度.     

Pre-sheath formation in an oblique magnetic field: fluid model and PIC simulation

We present some results of a one-dimensional fluid model with a floating electrode immersed in plasma with magnetic field applied at an oblique angle. The model equations are integrated numerically in order to find the space profiles of the ion velocities and electrostatic potential for various strenghts and angles of the magnetic field. We assume a collisionless magnetized pre-sheath with isothermal ions. The results are then compared with the spatial profiles obtained by a computer simulation. We use a BIT1 particle-in-cell code. The simulations input parameters are chosen in the way, that they resemble the fluid model as much as possible. Because the results of the simulation are given in the absolute SI units, they have to be normalized correctly. We evaluate the model results and compare them with the computer simulation results. Special attention is brought on formation of the pre-sheath with magnetic field applied at intermediate angles. The results of the simulation are in good qualitative agreement with the model.     

透平叶栅气膜冷却效果的数值研究

本文基于二维粘性数值模拟分析了某透平叶片气膜冷却的效果。在系统分析了冷却气流的喷射速度、喷射角度和温度的影响之后，得到了一些对叶片设计非常有用的结果和结论，同时探讨了本研究发展的数值方法和程序用于工程设计的可能性。     

啁啾脉冲在正常色散光纤中频域特性实验研究

对负啁啾脉冲在正常色散光纤中的频域特性进行了实验研究,并对实验结果进行了数值分析,实验和数值分析结果基本一致．