Study of Spin-One Heisenberg Model with Single-Ion Anisotropy by variational Curnulant Expansion

We study spin-one Heiseibergm odel with single-yon anisotropy for both easy-axis and easy-plane cases. Critical temperatures are obtained for different 3-dimensional lattices. Choice of trial action S₀ is discussed.     

利用SOLO分类理论分析中澳高考化学试题的差异

在简介SOLO分类理论的基础上,通过对2017-2018年澳大利亚VCE和江苏高考化学试卷的SOLO层次差异、试卷结构、试题的呈现方式、考查内容的用途方向和能力层次等方面进行比较,分析中澳试题各自的特色和优势。旨在让中学化学教师能多了解这种优势并将其应用在日常教学和命题中,使之发挥更大的作用。     

中澳化学教材中习题的比较研究*——以“金属”为例

以“金属”一章为例,对人教版高中化学教材和澳洲VCE课程的高中化学教材中习题进行比较研究,发现澳洲化学教材中的习题对学生的认知水平要求更高,能帮助学生进一步改变学习方式,更好地促进学生形成学科观念,加强学科思维训练,注意学科方法应用。     

A New Principle to Determine the Variational Parameter for the Variational-Cumulant Expansion

The key point of the variational-cumulant expanhon is the determination of the variational parameter. In this paper, we present the improved mean-field hypothesis (IMFH) which is the bdse to determine the parameter. The new method derived from the IMFH shows advantage over previous methods. The critical temperature and some thermal dynamical functions for the Heisenberg model are calculated with the new method.     

A simple axisymmetric extension to virtual cell embedding

Virtual cell embedding (VCE) is a simple cartesian gridding method that subdivides cells into discrete subcells to obtain the approximate obstructed cell area and side lengths. It can be used to make a very fast calculation method for the Euler equations in two dimensions. However, the original procedure for two spatial dimensions is inadequate for axisymmetric geometries, where radial co‐ordinates of cells and interfaces need to be known. Presented in this paper is a short, simple extension of the VCE method to handle axisymmetric cases with an accuracy consistent with the basic VCE surface representation in planar geometries. The method will be tested in basic conical flow simulations to show its usefulness for practical engineering design purposes. Copyright © 2007 John Wiley & Sons, Ltd.     

The Variational Cumulant Expansion Study of Spatially Anisotropic XY Model

With the variational-cumulant expansion (VCE) method, the critical temperature and spontaneous magnetization of the spatially anisotropic XY model are calculated up to the fourth order. The variational parameter is determined by the complete variational method and the results are compared with both the Monte Carlo results and the self-consistent harmonic approximation (SCHA) results. It is shown that the VCE method can give a better result than the SCHA method when the coupling between adjacent layers is small.     

高效液相色谱法测定化妆品中的维生素C及其衍生物

建立了化妆品中维生素C及其3种衍生物(抗坏血酸葡糖苷(AA-2G)、抗坏血酸磷酸酯镁(AA-2P)、抗坏血酸乙基醚(Only VCE))的高效液相色谱分析方法。化妆水、水乳液等含油脂较少的样品先采用30 mL 0.02 mol/L磷酸二氢钾溶液(pH 3.0)直接提取,然后定容至50 mL;面膏等含油脂较高及凝胶类、啫喱类的样品先加入1.0 mL二氯甲烷分散均匀后再加25 mL 0.02 mol/L磷酸二氢钾溶液(pH 3.0)提取。提取液在12000 r/min下离心后用0.22 μm滤膜过滤。样品分析采用YMC-Triart C18色谱柱,以0.02 mol/L磷酸二氢钾溶液(pH 3.0)和甲醇溶液为流动相,梯度洗脱,流速为1.0 mL/min,柱温为25 ℃,使用二极管阵列检测器(DAD)检测,检测波长为250 nm,外标法定量。结果显示:4种化合物在其线性范围内线性关系良好,相关系数(r²)均大于0.9999;方法的定量限(以信噪比为10计)为0.04~0.08 g/kg;添加水平为0.25~5.0 g/kg时的回收率为95.6%~101.0%,相对标准偏差为0.62%~3.0%。该方法前处理简单、回收率高、精密度好,适用于化妆品中维生素C及其衍生物的测定。