Nanocrystallization behaviour of a ternary amorphous alloy during isothermal annealing： a Monte Carlo simulation

The nanocrystallization behaviour of Zr70Cu20Ni10 metallic glass during isothermal annealing is studied by employing a Monte Carlo simulation incorporating with a modified Ising model and a Q-state Potts model. Based on the simulated microstructure and differential scanning calorimetry curves, we find that the low crystal-amorphous interface energy of Ni plays an important role in the nanocrystallization of primary Zr2Ni. It is found that when T〈T1max （where T1max is the temperature with maximum nucleation rate）, the increase of temperature results in a larger growth rate and a much finer mierostrueture for the primary Zr2Ni, which accords with the microstructure evolution in ＂flash annealing＂. Finally, the Zr2Ni/Zr2Cu interface energy σG contributes to the pinning effect of the primary nano-sized Zr2Ni grains in the later formed normal Zr2Cu grains.     

水中之月与天上的月亮等大吗？ ——凸面镜成像漫谈

 农历每月的十二、十三前后,若是晴天,在太阳还未落山之前,一轮明月便挂在东方蔚蓝色的天幕上.此时,于风平浪静的海面,人们可以欣赏到水天一色,天上明月与水中月亮交相辉映的美景.     

电子轰击电离源-离子阱质谱的质量范围优化程序研究

电子轰击电离源(Electron impact ion source,EI)是一种真空中使用的高效电离源,其电离效率可达到0.1％,几乎可以电离所有的物质.近年来,电子轰击电离源-离子阱质谱(EI-ion trap mass spectrometry,EI-ITMS)的发展使得便携式气相色谱-质谱联用仪广泛应用于有毒有...     

加权Hardy空间与加权L^p空间之间的算子内插

利用Calderon-Zygmund分解,给出了当w∈A1时加权Hardy空间与加权L^p空间之间的算子内插。     

High power terahertz pulses generated in intense laser-plasma interactions

Terahertz (THz) radiation has attracted much attention due to its wide potential applications. Though radiation can be generated with various ways, it is still a big challenge to obtain strong tabletop sources. Plasma, with the advantage of no damage limit, is a promising medium to generate strong THz radiation. This review reports recent advances on strong THz radiation generation from low-density gases and high-density solid targets at different laser intensities.     

纯铝熔体的微观动力学行为

利用反映原子多体相互作用的紧束缚模型及分子动力学计算机模拟技术,研究了液态金属Al的熔体结构与微观动力学行为。计算了纯金属熔体Al在不同温度下的双体分布函数,平均平方位移及速度自相关函数。模拟结果与实验结果吻合得很好,表明紧束缚模型能够描述纯铝熔体中原子间的相互作用     

行走时静摩擦力是否对人做功

这个问题一直有争论,而无定论.现发此文,希望引出更深入的分析和讨论.     

Syntheses,Crystal Structures and Bioactivities of Two Isatin Derivatives

The title compounds(Z)-3-(2-(3-chloropyridin-2-yl)hydrazono)indolin-2-one(A) and 7-bromo-(Z)-3-((4-pyridinyl)carboxlichydrazono)-2-indolinone(B) have been synthesized and structurally determined by elemental analysis and single-crystal X-ray diffraction studies.Compound A(C13H8ClN4O) belongs to the orthorhombic crystal system,space group Pca21 with a = 20.799(4),b = 4.9312(10),c = 11.764(2),V = 1206.6(4)3,Mr = 271.68,Dc = 1.496 g/cm3,μ = 0.313 mm-1,F(000) = 556,Z = 4,the final R = 0.0346 and wR = 0.0831 for 2683 observed reflections with I > 2σ(I).Compound B(C14H9BrN4O2) belongs to the triclinic crystal system,space group P1 with a = 6.6834(13),b = 7.0727(14),c = 14.285(3),α = 95.56(3),β = 99.00(3),γ = 102.95(3)°,V = 643.8(2)3,Mr = 345.16,Dc = 1.780 g/cm3,μ = 3.203 mm-1,F(000) = 344,Z = 2,the final R = 0.0487 and wR = 0.1167 for 2334 observed reflections with I > 2σ(I).The preliminary herbicidal bioassay reveals that compounds A and B have some inhibition both in vivo and in vitro against AHAS.     

基于OpenFOAM的磁流体求解器的开发和应用

基于计算流体力学平台OpenFOAM,本文开发了一套可压缩磁流体求解器,并将其应用于二维和三维的跨音速束流模拟.该求解器对OpenFOAM自带的密度基中心差分黎曼求解器rhoCentralFoam进行了修改,植入一个隐式压力分离算法用以控制磁场散度误差并保证模拟结果的数值精度.本文对此求解器进行了检测,证明了它的收敛阶在1—2之间,并将其应用到强激光等离子体的磁流体模拟.利用该求解器,本文讨论了外加均匀轴向磁场对激光等离子体喷流的影响,发现了喷嘴和结节位置与热压比开方之间的线性关系.本文还分析了电容线圈中产生的非均匀磁场对激光等离子体喷流的影响.初步模拟结果表明,当线圈中心磁场相同时,小尺寸线圈产生的磁场会加快喷嘴和结节的形成,等效的均匀轴向磁场更大.此模拟结果可以作为我们将来的磁化喷流实验的参考.同时,这样物理结果表明该磁流体求解器适合做面向激光等离子体实验的工程计算,可以应对构型比较复杂的场合.