论文标题
各向异性温度场中的最小熵产生
Minimal entropy production in anisotropic temperature fields
论文作者
论文摘要
温度场,化学电位和离子浓度梯度的各向异性提供了供应维持生命的动态过程的燃料。在各个环境中的动态流损失表现为熵产生。在这项工作中,我们考虑了各向异性温度热浴中过度阻尼的随机热力学系统的基本模型,并分析该问题以最小化熵产生,同时在有限的时间内驱动热力学状态之间的系统。值得注意的是,完全各向同性温度场中的熵产生可以表示为系统的热力学状态横穿路径的wasserstein-2。在存在各向异性温度场的情况下,熵产生的机理要复杂得多,因为除了耗散外,它还需要通过系统动力学在环境热源之间渗入能量。我们表明,在这种情况下,熵产生可以表示为适当约束且广义的最佳质量运输(OMT)问题的解决方案。与标准OMT的情况相反,即使热力学状态保持不变,熵产生也可能不会相同。从物理上讲,这是由于维持非平衡稳态(NESS)的事实会产生内在的熵成本。如前所述,NESS是生活和生活系统的标志,必须远离平衡。因此,我们最小化熵产生的问题在理解生物学过程(例如分子电机和运动蛋白)以及此类过程如何演变以优化可用资源的使用方面至关重要。
Anisotropy of temperature fields, chemical potentials and ion concentration gradients provide the fuel that feeds dynamical processes that sustain life. Dynamical flows in respective environments incur losses manifested as entropy production. In this work we consider a rudimentary model of an overdamped stochastic thermodynamic system in an anisotropic temperature heat bath, and analyze the problem to minimize entropy production while driving the system between thermodynamic states in finite time. It is noted that entropy production in a fully isotropic temperature field, can be expressed as the Wasserstein-2 length of the path traversed by the thermodynamic state of the system. In the presence of an anisotropic temperature field, the mechanism of entropy production is substantially more complicated as, besides dissipation, it entails seepage of energy between the ambient heat sources by way of the system dynamics. We show that, in this case, the entropy production can be expressed as the solution of a suitably constrained and generalized Optimal Mass Transport (OMT) problem. In contrast to the situation in standard OMT, entropy production may not be identically zero, even when the thermodynamic state remains unchanged. Physically, this is due to the fact that maintaining a Non-Equilibrium Steady State (NESS), incurs an intrinsic entropic cost. As already noted, NESSs are the hallmark of life and living systems by necessity operate away from equilibrium. Thus our problem of minimizing entropy production appears of central importance in understanding biological processes, such as molecular motors and motor proteins, and on how such processes may have evolved to optimize for available usage of resources.