Raman spectra of confined water adsorbed in nanoporous TiO_2 are obtained in experiment. TiO_2 samples with different pore diameters under different humidity conditions are investigated. The results indicate that the symmetric vibrational mode of water molecule is destroyed when relative humidity decreases. This indicates that the interaction between water molecules and surface of TiO_2 becomes stronger when the distance between water molecules and surface turns smaller, and the interaction plays a major role in depressing the symmetric vibrational peak. The spectra of confined water in TiO_2 and Vycor are compared. When filling fractions are the same, their spectra show distinctions no matter whether they are in partial filling condition or in full filling condition. The spectra of HDO confined in TiO_2 with different filling fractions are compared with each other. There is no clear distinction among their vibrational peaks, and the peaks mainly relate to asymmetric vibration. Therefore, the interaction between water molecules and the wall of pore decouples the symmetric vibrational mode only, and the influences on asymmetric vibrational mode show little differences among different filling fractions.
采用离散元法(discrete element method,DEM)对双分散圆盘颗粒体系在均匀压缩过程中的阻塞转变进行数值模拟,讨论了摩擦对临界阻塞态的影响。随着摩擦系数的增大,临界阻塞态的体积分数与平均接触数减小,其力学平均接触数与几何平均接触数的差异增大,同时各种接触类型的百分比也在发生改变。模拟结果还表明,摩擦系数为零以及无穷大的临界阻塞态是等静态堆积,临界阻塞态的体积分数随力学平均接触数呈线性增长的关系。
