Cao Yixin, Zhang Xiaodan, Kou Binquan, Li Xiangting, Xiao Xianghui, Fezzaa Kamel, Wang Yujie
Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Rd., Shanghai 200240, China.
Soft Matter. 2014 Aug 7;10(29):5398-404. doi: 10.1039/c4sm00602j. Epub 2014 Jun 16.
We present a dynamic synchrotron X-ray imaging study of the effective temperature Teff in a vibrated granular medium. By tracking the directed motion and the fluctuation dynamics of the tracers inside, we obtained Teff of the system using the Einstein relationship. We found that as the system unjams with increasing vibration intensities Γ, the structural relaxation time τ increases substantially which can be fitted by an Arrhenius law using Teff. And the characteristic energy scale of structural relaxation yielded by the Arrhenius fitting is E = 0.20 ± 0.02pd(3), where p is the pressure and d is the background particle diameter, which is consistent with those from hard sphere simulations in which the structural relaxation happens via the opening up of free volume against pressure.
我们展示了一项关于振动颗粒介质中有效温度(T_{eff})的动态同步加速器X射线成像研究。通过追踪内部示踪剂的定向运动和涨落动力学，我们利用爱因斯坦关系获得了系统的(T_{eff})。我们发现，随着系统在振动强度(\Gamma)增加时发生解堵塞，结构弛豫时间(\tau)大幅增加，这可以用基于(T_{eff})的阿伦尼乌斯定律来拟合。并且，阿伦尼乌斯拟合得出的结构弛豫特征能量尺度为(E = 0.20 \pm 0.02pd^3)，其中(p)是压力，(d)是背景颗粒直径，这与硬球模拟结果一致，在硬球模拟中，结构弛豫是通过抵抗压力打开自由体积而发生的。
