Two-dimensional Yukawa liquids: correlation and dynamics

A combined theoretical and molecular dynamics (MD) simulation study of the collective modes and their dispersion in a two-dimensional Yukawa system in the strongly coupled liquid state is presented. The theoretical analysis relies upon the quasilocalized charge approximation; the MD simulation generates static pair correlation functions and dynamical current-current correlation spectra.     

Dynamical structure functions,collective modes,and energy gap in charged-particle bilayers

The dynamical properties of strongly coupled charged-particle bilayers are investigated by molecular dynamics (MD) simulation and theoretical analysis. The spectra of the current correlation functions show the existence of two (in-phase and out-of-phase) longitudinal and two (in-phase and out-of-phase) transverse collective modes. The out-of-phase modes possess finite frequencies at wave numbers k-->0, confirming the existence of the predicted long-wavelength energy gap in the bilayer system. A theoretical model based on an extended Feynman ansatz for the dynamical structure functions provides predictions on the strength of the collective modes that are verified by the MD experiment.     

神光-Ⅲ 3ω光路自动准直系统设计

基于闭环反馈控制理论，对神光-Ⅲ 3ω光源自动准直系统进行设计，分析系统的工作原理、控制算法和软件控制流程。对准直过程中电动控制对于控制结果影响的变化规律建立了数学模型，旨在克服俯仰和方位相互联动对准直精度的影响。采用二维镜架自动准直方案，使准直偏差在预定调整范围内不断收敛。神光-Ⅲ调试现场的准直结果证明：该自动准直系统达到了设计要求，即自动准直系统在半小时内完成8路光束的光束准直，其角度误差≤5.0%/空间滤波器小孔直径,平移误差≤1.0%(光束近场直径精度)。     

Strong coupling effects in binary Yukawa systems

We analyze the acoustic collective excitations in two- and three-dimensional binary Yukawa systems, consisting of two components with different masses. A theoretical analysis reveals a profound difference between the weakly and strongly correlated limits: at weak coupling the two components interact via the mean field only and the oscillation frequency is governed by the light component. In the strongly correlated limit the mode frequency is governed by the combined mass, where the heavy component dominates. Computer simulations in the full coupling range extend and confirm the theoretical results.     

基于彩色光栅投影的快速三维测量方法

 针对条纹投影术提取物体高度信息的问题,提出了一种新的基于彩色光栅投影的三维测量方法。对选取G分量为255,R,B分量各取0或255而组成的青、白、黄、绿四色遵循格雷码原理进行编码,然后将G分量作正弦调制形成投影光栅投向被测物体。提取采集到的光栅变形图中G分量,利用傅里叶变换方法得到其初始相位;同时对采集到图像中的R,B分量作阈值迭代分割而G分量自动赋值为255,综合三分量信息得到条纹颜色信息进而获取条纹的周期信息,从而展开相位。全过程仅需投影一幅彩色光栅图就能完成三维测量,实验结果表明该算法易于实现,在测量实时性和精确性上表现良好。     

诃子与川楝子配伍后挥发油化学成分分析

采用水蒸气蒸馏法将诃子与川楝子按1∶1的质量比配伍后提取挥发油,并用GC-M S联机技术对其化学成分进行研究,分离出249个组分,鉴定了其中的13个,主要成分有单[2-乙基己基]邻苯二甲酸、2,2′-亚甲基叔丁基对甲酚,乙基（2E）-3-[4-甲氧基苯基]-2-丙烯、7-甲基-Z-十四烯-1-醇酯。     

地声参数及传播损失不确定性估计与建模

地声参数的不确定性对水声传播具有重要的影响。通过贝叶斯理论建立水声环境不确定性推理模型,理论推导了地声参数的似然函数以及地声参数和传播损失的后验概率密度,并采用MCMC(Markov Chain Monte Carlo)进行了仿真计算,给出了地声参数的二维后验联合概率密度和一维边缘概率密度,在此基础上对传播损失的不确定性进行了估计,得到了传播损失80%的可信区间。仿真和实验结果表明,该方法适用于地声参数反演和不确定性估计,并能获取因地声参数不确定性导致的传播损失不确定性估计。     

Ground state of magnetic dipoles on a two-dimensional lattice: structural phases in complex plasmas

We study analytically and by molecular dynamics simulations the ground state configuration of a system of magnetic dipoles fixed on a two-dimensional lattice. We find different phases, in close agreement with previous results. Building on this result and on the minimum energy requirement we determine the equilibrium lattice configuration, the magnetic order (ferromagnetic versus antiferromagnetic), and the magnetic polarization direction of a system of charged mesoscopic particles with magnetic dipole moments, in the domain where the strong electrostatic coupling leads to a crystalline ground state. Orders of magnitudes of the parameters of the system relevant to possible future dusty plasma experiments are discussed.     

大离轴量凹面取样镜的设计

根据系统的使用要求以及椭球面特有的成像性质,提出使用离轴椭球面来完成光束取样和完善成像的设计方式.利用设计输入,计算出镜面的初始结构参数,得到离轴椭球面的二次曲线方程,将计算结果带入光学设计软件ZEMAX中验证成像质量.结果表明:离轴椭球面不但将物点和像点分开,减小了系统的长度,而且在像点处成完善像,将离轴成像转换为轴上成像,使后续光斑成像系统的高质量成像易于实现.