Gas-liquid phase coexistence and finite-size effects in a two-dimensional Lennard-Jones system

The gas-liquid phase coexistence in a two-dimensional Lennard-Jones system is investigated using Maxwell construction method together with molecular dynamics simulations.The results of phase coexistence in different truncations of the potential are compared with data obtained from the literature,and the corresponding critical properties calculated.The crossover from Ising-like to mean field behavior is observed and confirmed as the temperature approaches the critical point from below.Performing simulations on systems with different sizes,we find that a finite size effect is more significant than those shown in most of the previous results,and a lower critical temperature is obtained when the full extent of this finite size effect is considered.     

Preparation, structure, and properties of polyurethane foams modified by nanoscale titanium dioxide with three different dimensions

TiO2-based nanosheets (TiNSs), TiO2-based nanotubes (TiNTs) were prepared by hydrothermal processing, and polyurethane foams with TiO2 nanopowders (P25), TiNSs and TiNTs were synthesized by free-rising foaming method. The Fourier-transform infrared (FT-IR) spectra show that the addition of titanium dioxide does not affect the chemical structure of polyurethane foam. However, microscope observations show that PU/TiNSs composite foams have more uniform cells and the average aperture smaller than that of pure poly-urethane foams. According to the results of thermal analysis, the PU/TiNSs composite foams have better thermal stability, the temperature of decompostion occurring with a maximum weight loss rate is about 30 ℃ higher than that of pure PU foams. The decompostion temperatures are 167 ℃ and 148 ℃ for the PU/P25 composite foams and the PU/TiNTs composite foams respectively, which are lower than that of pure PU foams. Moreover, with the addition of the fillers, the sound absorption property also has changed; the addition of TiNSs improved the sound absorbing property efficiently. The better thermal stability and sound absorption of PU/TiNSs composite foams are mainly due to the uniform cells diffuse and smaller aperture.     

立体预测中的地质几何方法的原理和应用

本文研究了当前正在发展的立体定量预测中的地质几何方法的基本原理和数学模型及其应用。作者采用多项式函数和趋势-剩余分析对控矿地质界面(如地层界面、不整合面、断裂面及侵入接触界面等)进行形态模拟,并根据模拟所得地质几何参数对矿体进行空间定位和深边部立体预测,然后采用三维趋势分析或克里金法对预测地段的矿床值进行定量估计。四个矿床的预测应用证明该方法实际效果较好。     

余子空间的性质

在n维向量空间V中,任一非平凡子空间W的余子空间是不唯一的,本文给出了W的余子空间的一般表示法,并讨论了W的任意两个余子空间的和与交的维数取值范围。     

复多项式的Julia集的Hausdorff维数

利用分形几何学的有关理论和方法，给出了复数Ｃ取不同值时的多项式ｆ（ｚ）＝ｚｎ＋Ｃ，（ｎ≥２）的Ｊｕｌｉａ集的Ｈａｕｓｄｏｒｆｆ维数估计．     

节理岩体损伤及分形耦合分析

计算了锦屏水电站解放沟坝段平硐测点节理岩体的损伤张量、充填维数及多重分维值；建立了充填维数与连通率、多重分维值与最大主损伤值的关系式，初步明确了分维的物理意义，并对其可能的应用作了分析。     

几何Rademacher级数的图的Hausdorff维数

本证明了对任意α∈（０，１），几何Ｒａｄｅｍａｃｈｅｒ级数ｆａ（ｘ）＝Σ＾∞ｉ＝１２＾－ａｉＲ（２＾ｉ－１ｘ）（ｘ∈［０，１］）的图的Ｈａｕｓｄｏｒｆｆ维数为２－ａ。     

两维油藏物理模拟装置

本装置用于石油开采的模拟研究，包括针对具体油藏的模拟和采油机理研究。模型是尺寸为７００ｍｉｎ×３００ｍｍ×１０ｍｍ的矩型平面，可以绕中心轴旋转置于任何倾角。模型设计最大工作压力为０．５ＭＰａ，最高工作温度为１５０℃。模型一侧透明，可用肉眼或光学仪器观察及记录现象。另一侧开有１６８个测孔，可测量实验时的温度场和压力场。模型的注入端和产出端各开有８个孔，模拟各种射开情况。