标题： 活性物质中的自维持摩擦冷却 显示英文标题

标题： Self-sustained frictional cooling in active matter

摘要： 自然中的冷却过程通常是由与冷源或浴的外部接触产生的。 根据热力学定律，系统的最终温度由环境的温度决定。 在这里，我们报告了一种主动粒子的自发内部冷却现象，该现象在没有外部接触的情况下发生。 这种效应被称为“自维持摩擦冷却”，是活性和干（库仑）摩擦相互作用的结果，并且由于粒子被邻居紧密包围而自我维持。 如果一个主动粒子在其笼中移动，在与相邻粒子碰撞后，干摩擦会阻止进一步的运动，从而将粒子冷却到极低的温度。 我们通过主动颗粒机器人的实验和模拟验证了这种自维持冷却，并识别出密集的摩擦停滞簇与高温、稀疏区域共存。 我们的发现为二维群体机器人提供了潜在的应用，其中活性和干摩擦可以作为可外部调节的机制来调节群体的动力学和结构特性。 显示英文摘要

摘要： Cooling processes in nature are typically generated by external contact with a cold reservoir or bath. According to the laws of thermodynamics, the final temperature of a system is determined by the temperature of the environment. Here, we report a spontaneous internal cooling phenomenon for active particles, occurring without external contact. This effect, termed ``self-sustained frictional cooling'', arises from the interplay between activity and dry (Coulomb) friction, and in addition is self-sustained from particles densely caged by their neighbors. If an active particle moves in its cage, dry friction will stop any further motion after a collision with a neighbor particle thus cooling the particle down to an extremely low temperature. We demonstrate and verify this self-sustained cooling through experiments and simulations on active granular robots and identify dense frictional arrested clusters coexisting with hot, dilute regions. Our findings offer potential applications in two-dimensional swarm robotics, where activity and dry friction can serve as externally tunable mechanisms to regulate the swarm's dynamical and structural properties.