Song Chaoming, Wang Ping, Makse Hernán A
Levich Institute and Physics Department, City College of New York, New York, NY 10031, USA.
Proc Natl Acad Sci U S A. 2005 Feb 15;102(7):2299-304. doi: 10.1073/pnas.0409911102. Epub 2005 Feb 8.
A densely packed granular system is an example of an out-of-equilibrium system in the jammed state. It has been a longstanding problem to determine whether this class of systems can be described by concepts arising from equilibrium statistical mechanics, such as an effective temperature and compactivity. The measurement of the effective temperature is realized in the laboratory by slowly shearing a closely packed ensemble of spherical beads confined by an external pressure in a Couette geometry. All of the probe particles considered in this study, independent of their characteristic features, equilibrate at the same temperature, given by the packing density of the system.
密集堆积的颗粒系统是处于堵塞状态的非平衡系统的一个例子。确定这类系统是否能用平衡统计力学中产生的概念（如有效温度和压缩率）来描述，一直是个长期存在的问题。有效温度的测量是在实验室中通过在库埃特几何结构中缓慢剪切由外部压力限制的紧密堆积的球形珠子集合来实现的。本研究中考虑的所有探测颗粒，无论其特征如何，都在由系统堆积密度给出的相同温度下达到平衡。
