41 research outputs found
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