Influence of particle packing structure on sound velocity

The anisotropy in the particle systems of different packing structures affects the sound velocity. The acoustic propagation process in four kinds of packing structures(denoted as S45, H60, S90, and D) of two-dimensional granular system is simulated by the discrete element method. The velocity v_(tof) obtained by the time of flight method and the velocity vc obtained from the stiffness tensor of the system are compared. Different sound velocities reflect various packing structures and force distributions within the system. The compression wave velocities of H60 and S90 are nearly the same, and transmit faster than that of D packing structure, while the sound velocity of S45 is the smallest. The shear wave velocities of S45 and H60 are nearly the same, and transmit faster than that of D packing structure. The compression wave velocity is sensitive to the volume fraction of the structure, however, the shear wave velocity is more sensitive to the geometrical structure itself. As the normal stress p is larger than 1 MPa, v_(tof) and vc are almost equal, and the stiffness tensors of various structures explain the difference of sound velocities. When the normal stress is less than 1 MPa, with the coordination number unchanged, the law v_(tof) ∝ p~(1/4) still exists. This demonstrates that apart from different power laws between force and deformation as well as the change of the coordination number under different stresses, there are other complicated causes of v_(tof)∝ p~(1/4), and an explanation of the deviation from v_(tof) ∝ p~(1/6) is given from the perspective of dissipation.     

Ti/Sn（1-x）IrxO2电极制备及电生活性氯特性

通过热分解法制备了Ti/Sn(1-x)IrxO2电极,应用SEM观察了电极的表面形貌,通过线性伏安法、循环伏安法等实验方法测试了电极的电化学性能。实验结果表明,Ti/Sn0.7Ir0.3O2电极具有较好的析氯活性;电解产生的活性氯浓度随电流密度的增加先增加后降低;升高电解温度不利于活性氯的产生。     

几何光学法和波动光学法测量液体折射率的比较

利用波动光学的牛顿环和光栅的方法、几何光学的小棱角三角杯反射法以及三棱杯最小偏向角法测量了液体的折射率,讨论实验中的一些问题并比较了各方法的优缺点和误差。最后研究了液体浓度对折射率的影响。