On the equivalence of the Nernst theorem and its consequence

One general consequence of the Nernst theorem is derived, i.e., the various heat capacities of a thermodynamic system under different constraints approach zero as the temperature approaches absolute zero. The temperature dependence of the heat capacity of any thermodynamic system at ultra-low temperatures is revealed through this consequence. Moreover, the general form and the simplest expression of the heat capacities of thermodynamic systems at ultra-low temperatures are deduced. Some significant discussion and results are given. One new research method is provided by using this consequence. Finally, the equivalence between the Nernst theorem and its consequence is rigorously proved, so that this consequence may be referred to another description of the third law of thermodynamics

Theoretical bound of the efficiency of learning with coarse-graining

A thermodynamic formalism describing the efficiency of information learning is proposed, which is applicable for stochastic thermodynamic systems with multiple internal degree of freedom. The learning rate, entropy production rate (EPR), and entropy flow from the system to the environment under coarse-grained dynamics are derived. The Cauchy-Schwarz inequality has been applied to demonstrate the lower bound on the EPR of an internal state. The inequality of EPR is tighter than the Clausius inequality, leading to the derivative of the upper bound on the efficiency of learning. The results are verified in cellular networks with information processes

Theoretical bound of the efficiency of learning

A unified thermodynamic formalism describing the efficiency of learning is proposed. First, we derive an inequality, which is more strength than Clausius's inequality, revealing the lower bound of the entropy-production rate of a subsystem. Second, the inequality is transformed to determine the general upper limit for the efficiency of learning. In particular, we exemplify the bound of the efficiency in nonequilibrium quantum-dot systems and networks of living cells. The framework provides a fundamental trade-off relationship between energy and information inheriting in stochastic thermodynamic processes

A two-stage sodium thermal electrochemical converter: Parametric optimization and performance enhancement

[EN]An asymmetric two-stage sodium thermal electrochemical converter and its optimum performance are studied by means of an improved analytical model including the main losses in the overall system. Based on the study of a single-stage sodium thermal electrochemical converter, the inner process is divided into two stages including one at the 1300 K temperature (evaporator) and the other at the 800–1300 K intermediate temperature with the aim of improving efficiency. The parametric optimum selection criteria of a few main parameters of the two-stage device are provided and the coupling of the separate stages in an overall optimum system in terms of the appropriate intermediate temperature is particularly stressed. The maximum efficiency of the proposed overall system can attain 36.2%, which is 17.5% higher than that of the best performing single-stage device, and increase up to 34.1% and 24.8% over the existing two-stage devices designed by two research groups, respectively. The Pareto front obtained from numerical multiobjective and multiparametric methods endorses previous findings and visually presents the space of the states and the energetic properties of the overall arrangement compared with the corresponding data for the isolated first and second stages.China Scholarship Council under the State Scholarship Fund (No. 201906310095