Molecular dynamics studies of thermal conductivity time correlation functions

The Green–Kubo time correlation function for the thermal conductivity in liquid argon is studied for a thermodynamic state close to the triple point by standard molecular dynamics simulations. The collective heat flux vector has been separated into contributions originated at the kinetic energy, the intermolecular potential and the pair virial function. Furthermore, the Green–Kubo time correlation functions have been broken down into partial n-body terms (n=1,2,3,4). The most important contribution to the thermal conductivity is represented by the auto correlation of the virial term. In contrast to other collective phenomena described by time correlation functions involving n-body terms, the partial Green–Kubo time correlation functions for the thermal conductivity are not affected by exponential long-time tails.     

Auto-correlation Properties of Scattering Light in Ultrasound-modulated Random Media

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｅｘｔｒａｃｔｉｎｇｕｓｅｆｕｌｉｎｆｏｒｍａｔｉｏｎａｂｏｕｔｔｈｅｄｙｎａｍｉｃａｌｓｃａｔｔｅｒｅｒｓｆｒｏｍｔｈｅｔｅｍｐｏｒａｌｆｌｕｃｔｕａｔｉｏｎｓｏｆｓｃａｔｔｅｒｉｎｇｌｉｇｈｔｆｉｅｌｄｈａｓｂｅｅｎｓｔｕｄｉｅｄｆｏｒｍａｎｙｙｅａｒｓ.Ｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｄｉｆｆｕｓｉｎｇ ｗａｖｅｓｐｅｃｔｒｏｓｃｏｐｙ[1～ 3 ] (ＤＷＳ)ｈａｓｅｘｔｅｎｄｅｄｔｈｅｔｒａｄｉｔｉｏｎａｌａｐｐｌｉｃａｔｉｏｎｓｉｎｓｉｎｇｌｅ ｓｃａｔｔｅｒｉｎ…     

超声调制漫射光子自相关的Monte Carlo模拟

本文首次用Monte Carlo方法研究了超声调制生物介质中漫射光子的时间自相关性质,讨论了超声参量、运动参量和散射参量对自相关函数的影响.正常生物组织和病变生物组织的自相关函数有明显的差别,超声调制自相关函数为光学医学诊断提供一种新参考.     

利用相关技术测量激光脉冲的对比度

研究了在放大激光脉冲的噪声测量中，二阶相关技术和三阶相关技术的差别。理论分析显示，三阶相关技术不仅可以显示噪声脉冲的正确位置，而且具有比二阶相关技术更高的测量精度，数值计算也验证了这一点。     

Longitudinal and bulk viscosities of binary fluid mixtures

Expressions for zeroth, second and fourth sum rules of longitudinal and bulk stress auto correlation functions have been derived for binary fluid mixtures. Longitudinal and bulk viscosities of an Ar–Kr mixture have been calculated using Mori's memory function formalism coupled with the sum rules of longitudinal and bulk stress auto correlation functions. The results obtained are compared with the molecular dynamics simulation. Mass dependence of the longitudinal and bulk viscosities has been studied for different compositions of an isotopic mixture at different densities and temperatures. For very large mass ratio, the longitudinal and bulk viscosities of the isotopic mixture are more dependent on mole fraction than on mass.     

用并行计算的方法研究He原子基态关联能

用组态相互作用方法计算了Ｈｅ原子基态电子关联能，为了既得到较高精度又克服计算机上遇到的困难，采用了并行分块消去迭代法，同时在多个处理器上并行计算。得到了较好的结果，并且对进一步开展对三个以上电子体系的关联能并行计算有一定的参考意义。     

Molecular dynamics study of two-and three-dimensional classical fluids using double Yukawa potential

We have carried out a molecular dynamics simulation of two- and three-dimensional double Yukawa fluids near the triple point. We have compared some of the static and dynamic correlation functions with those of Lennard—Jones, when parameters occurring in double Yukawa potential are chosen to fit Lennard-Jones potential. The results are in good agreement. However, when repulsive and attractive parameters occurring in double Yukawa potential are varied, we found distinct differences in static and dynamic correlation functions. We have also compared the two-dimensional correlation functions with those of three-dimensional to study the effect of dimensionality, near the triple point region.     

短数据量动态光散射颗粒测量信号去噪方法

在动态光散射测量中,采用自相关法对测量信号进行去噪,其去噪效果受数据量影响。根据噪声和信号的不同特点,采用小波包变换对信号进行去噪,能够提高信噪比,改善粒径反演结果。采用两种去噪方法,对粒径为100 nm颗粒的散射信号进行去噪并反演,小波包去噪法能够改善粒径误差0.88%~6.41%。在不同数据量下,由两种去噪法的反演结果对比看出,在短数据量时,小波包去噪效果更好,当数据量大于1×106时,两种去噪法效果相差不大。因此,小波包去噪法更适合于短数据量的动态光散射颗粒测量。     

乳菇和红菇的红外光谱及其二维相关红外光谱的分析与鉴别

采用傅里叶变换红外光谱原始谱、二阶导数光谱以及二维相关谱的三级鉴定方法,对红菇属和乳菇属六种蘑菇进行了鉴别分析。六种样品的原始光谱吸收峰非常相似,主要为蛋白质和碳水化合物的吸收组成,但在各样品吸收峰强度、峰形和峰位上仍有微小差异。对其进行二阶导数分析,在二阶导数谱中,1 800～1 400和1 200～800 cm-1范围内的吸收峰强度、位置、峰形状显示出明显差异。二维相关红外光谱提高了光谱的分辨率;对六种蘑菇样品进行二维相关红外光谱分析,发现在1 690～1 420 cm-1范围内,三种乳菇出现了3个明显的自动峰,另外三种红菇出现了4个自动峰,而且自动峰和交叉峰位置、强度均不同;在1 110～920 cm-1二维光谱范围内,六种蘑菇的自动峰和交叉峰的数量、位置和强度也都不同;说明不同样品中蛋白质和糖类化合物的显著不同。结果表明：应用红外光谱、二阶导数谱和二维相关红外光谱三级鉴定的技术可以快速有效地分析和鉴别辣乳菇、绒白乳菇、香乳菇、稀褶红菇、变绿红菇和近似酒红菇。该多级鉴定的方法对于分类鉴别蘑菇是一种快速、准确、有效的方法。     

动态光散射中的多普勒效应

动态光散射中的多普勒效应郭凤岐１）刘秋霞２）（武汉工业大学数理系材料学院武汉４３００７０）ＤｏｐｐｌｅｒＥｆｅｃｔｉｎＤｙｎａｍｉｃＬｉｇｈｔＳｃａｔｅｒｉｎｇＧｕｏＦｅｎｇｑｉ，ＬｉｕＱｉｕｘｉａ（Ｄｅｐｔ．ｏｆＭａｔｈ．ａｎｄＰｈｙｓ．，Ｗｕｈａ...     

730 eV电子碰撞He原子(e, 2e)电离的三重微分截面

考虑初态He原子电子间的关联效应、末态敲出电子与剩余束缚电子间的关联效应和末态屏蔽效应, 计算和分析了在共面、大能量损失和小动量转移这一特殊几何条件下730eV电子离化He原子的三重微分截面. 所得结果与Stevenson等人的相对实验数据和CCC理论计算结果进行比较发现: 所得到的理论曲线能够反映实验数据给出的三重微分截面的结构特征.     

730 eV电子碰撞He原子(e, 2e)电离的三重微分截面

考虑初态He原子电子间的关联效应、末态敲出电子与剩余束缚电子间的关联效应和末态屏蔽效应, 计算和分析了在共面、大能量损失和小动量转移这一特殊几何条件下730eV电子离化He原子的三重微分截面. 所得结果与Stevenson等人的相对实验数据和CCC理论计算结果进行比较发现: 所得到的理论曲线能够反映实验数据给出的三重微分截面的结构特征.     

Brownian and advective dynamics in microflow studied by coherent X‐ray scattering experiments

Combining microfluidics with coherent X‐ray illumination offers the possibility to not only measure the structure but also the dynamics of flowing samples in a single‐scattering experiment. Here, the power of this combination is demonstrated by studying the advective and Brownian dynamics of colloidal suspensions in microflow of different geometries. Using an experimental setup with a fast two‐dimensional detector and performing X‐ray correlation spectroscopy by calculating two‐dimensional maps of the intensity auto‐correlation functions, it was possible to evaluate the sample structure and furthermore to characterize the detailed flow behavior, including flow geometry, main flow directions, advective flow velocities and diffusive dynamics. By scanning a microfocused X‐ray beam over a microfluidic device, the anisotropic auto‐correlation functions of driven colloidal suspensions in straight, curved and constricted microchannels were mapped with the spatial resolution of the X‐ray beam. This method has not only a huge potential for studying flow patterns in complex fluids but also to generally characterize anisotropic dynamics in materials.     

分段自相关动态光散射法测量亚微米粒度

介绍了动态光散射法测量微粒尺度的原理，通过对相关函数相对的分析，提出了分段自相关的方法，该方法解决了高速，大数据量采集的困难，又不显著影响相关函数的精度，给出了实验装置及实验结果，测量结果与标准样品的标称值相符。     

System of Recording Radiation for Analysis of Third-Order Correlation Functions

A system of recording the triple correlation of a photodetection signal for the spectral analysis of optical radiation is proposed. The results of the recording of the correlation components and of the computer calculation of the laser radiation spectral line profile are presented.     

Triple correlation in a plasma and the collision integral for the dual correlation function

A solution is derived to the equation for the triple correlation function of a system of charged particles, allowing for the effects of dynamic polarization and yielding an equation for dual correlation analogous to the kinetic equation for the simple distribution function.     

荧光相关光谱测定溶液中胭脂红的含量

使用FLS920P型荧光光谱仪测量了20个合成色素胭脂红溶液样本的荧光发射谱,实验表明：胭脂红的最佳激发波长为300 nm,在此波长激发光下,荧光峰值波长为440 nm。同时测量相同条件下超纯水的光谱数据作为参考光谱,进行与胭脂红溶液光谱数据的相关计算,构建以浓度为外扰的荧光相关光谱。采用sym8小波函数4尺度降噪,将降噪后的同步相关光谱数据、自相关光谱数据应用偏最小二乘回归(PLSR)算法进行预测,建立溶液中胭脂红含量的定量模型,结果表明：采用同步相关光谱建模的预测相关系数为99.863%,预测均方根误差为0.414 μg·mL-1;而采用自相关光谱建模的预测相关系数为99.940%,预测均方根误差为0.303 μg·mL-1。对比可知,自相关光谱数据有效地避免了信息冗余,预测结果更为可靠。该方法无需样本处理,操作简单,为食品安全检测提供了一种新的思路。     

A Useful Technique to Fabricate Fan-out Grating

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Three-fold photoelectron counting statistics for gaussian light

The three-fold generating function Q(λ₁, λ₂, λ₃) for photocount statistics is evaluated directly from the gap integral equation in the short counting time regime. The triple joint probabilities and the triple photoelectron correlation function are obtained via Q(λ₁, λ₂, λ₃) in terms of the field correlation function of the incident quasimonochromatic radiation. Three-fold moments are also evaluated via another approach which permits an extension to arbitrary counting times.