Statistical physics in equilibrium grants us one of its most powerful tools: the equipartition principle. It states that the degrees of freedom of a mechanical system act as a thermometer: temperature is equal to the mean variance of their oscillations divided by their stiffness. However, when a non-equilibrium state is considered, this principle is no longer valid. In our experiment, we study the fluctuations of a micro-cantilever subject to a strong heat flow, which creates a highly non-uniform local temperature. We measure independently the temperature profile of the object and the temperature yielded from the mechanical thermometers, thus testing the validity of the equipartition principle out of equilibrium. We demonstrate how the fluctuations of the most energetic degrees of freedom are equivalent to the temperature at the base of the cantilever, even when the average temperature is several hundreds of degrees higher. We then present a model based on the localised mechanical dissipation in the system to account for our results, which correspond to mechanical losses localised at the clamping position.

中文翻译：

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受热流影响的机械系统中的扩展均分：局部耗散的情况

平衡中的统计物理学为我们提供了最强大的工具之一：均分原理。它指出机械系统的自由度充当温度计：温度等于其振荡的平均方差除以它们的刚度。但是，当考虑非平衡状态时，该原则不再有效。在我们的实验中，我们研究了受强热流影响的微悬臂梁的波动，这会产生高度不均匀的局部温度。我们独立地测量物体的温度分布和机械温度计产生的温度，从而测试不平衡的均分原理的有效性。我们展示了最高能量自由度的波动如何与悬臂底部的温度相等，即使平均温度高出数百度。然后我们提出了一个基于系统中局部机械耗散的模型来解释我们的结果，这对应于夹紧位置的局部机械损耗。