Rotation of a gear powered by active particles is numerically investigated in a circular chamber. Due to the nonequilibrium properties of active particles, net gear rotation is achieved in a bath composed of self-propelling particles. Our setup can convert the random motion of active particles into the directional rotation of the ratchet gear. The direction of rotation is determined by the asymmetry of the gear and the persistence length (the ratio of the self-propulsion speed to the rotation diffusion coefficient) of active particles. Remarkably, the direction of rotation for large persistence length is opposite to the direction of rotation for small persistence length. Therefore, for a given asymmetric gear, we can observe the rotation reversal when tuning the system parameters (e.g., the self-propulsion speed, the rotation diffusion coefficient, and the packing fraction of active particles). Our findings are relevant to the experimental pursuit of rectifying random motion to directional motion in active matter.

中文翻译：

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由活性粒子驱动的棘轮齿轮的旋转反转

在圆形腔室中对由活性粒子驱动的齿轮的旋转进行了数值研究。由于活性粒子的非平衡特性，在由自推进粒子组成的浴槽中实现了净齿轮旋转。我们的设置可以将活动粒子的随机运动转换为棘轮的定向旋转。旋转方向由齿轮的不对称性和活性粒子的持续长度（自航速度与旋转扩散系数的比值）决定。值得注意的是，大持久长度的旋转方向与小持久长度的旋转方向相反。因此，对于给定的非对称齿轮，我们可以在调整系统参数时观察到旋转反转（例如、自推进速度、旋转扩散系数和活性粒子的堆积率）。我们的发现与将活性物质中的随机运动纠正为定向运动的实验追求有关。