Hasil untuk "Thermodynamics"

M. J. Moran, H. Shapiro

P. Nugent, Y. Belmabkhout, S. Burd et al.

Y. Ichikawa, A. Selvadurai

A. L. Kuzemsky

D. Gaskell

G. Gibbons, S. Hawking

S. Hawking, D. Page

P. Flory

M. Biot

M. Rekharsky, Y. Inoue

T. Jacobson

The Einstein equation is derived from the form of black hole entropy together with the fundamental relation $\delta Q=TdS$ connecting heat, entropy, and temperature. The key idea is to demand that this relation hold for all the local Rindler horizons through each spacetime point. Viewed in this way, the Einstein equation is an equation of state. It is born in the thermodynamic limit as a relation between thermodynamic variables, and its validity is seen to depend on the existence of local equilibrium conditions. As such there is no reason to think the gravitational field equations should be quantized, i.e., promoted to operator relations.

F. Bates, G. Fredrickson, G. Fredrickson

Robert M. Wald

J. Ansermet, S. Brechet

The thermodynamics of irreversible processes is based on the expression of the entropy source density derived in the previous chapter. From it, phenomenological laws of transport can be presented in a unified way. Heat transport is given by Fourier’s law that leads to a heat equation in which Joule and Thomson effects can be included. It can explain thermal dephasing, heat exchangers and effusivity. Matter transport leads to the Dufour and Soret effects, which imply Fick’s law and the diffusion equation, which can be used to discuss Turing patterns and ultramicroelectrode. Transport of two types of charge carrier leads to the notion of diffusion length, giant magnetoresistance and planar Ettingshausen effect. Transport can be perpendicular to the generalised force, as in the Hall, Righi-Leduc and Nernst effects. The formalism accounts also for thermoelectric effects such as the Seebeck and Peltier effects, with which to analyse thermocouples, a Seebeck loop, adiabatic thermoelectric junctions, the Harman method of determing the ZT coefficient of a thermoelectric material and the principle of a Peltier generator.

A. Ebelegi, N. Ayawei, D. Wankasi

A complete study of adsorption processes will be less complete if the structure and dynamics of its different elements and how they interact is not well captured. Therefore, the extensive study of adsorption thermodynamics in conjunction with adsorption kinetics is inevitable. Measurable thermodynamic properties such as temperature equilibrium constant and their non-measurable counterparts such as Gibbs free energy change, enthalpy, entropy etc. are very important design variables usually deployed for the evaluation and prediction of the mechanism of adsorption processes.

S. McCormack, A. Navrotsky

Abstract With the hype of “high entropy” alloys and more recently, “high entropy” ceramics and “high entropy” oxides (HEOs), there has been a great push to investigate and characterize systems with 5 or more components. This push has been extremely beneficial for the materials community as it has led to the development of many new systems with targeted applications. However, with our desire to find “new” and “exotic” materials, we have not spent enough time to step back and think deeply about the fundamental thermodynamic constraints that will guide design of future HEOs. Here, we present data-driven discussions with examples that have been collected from the fields of geology and materials science over the past 50 years to highlight critical thermodynamic parameters and principles that can be used for the design of HEOs. The goal of HEOs is to push the limit of the number of components in a single-phase solid solution to achieve unique and tunable properties. True single-phase HEOs are stabilized if the positive entropy of formation more than compensates an unfavorable enthalpy of formation above some critical temperature, making the overall Δ G f negative i.e. the HEO phase is “entropy stabilized”. Under ideal mixing, the number of components in a solid solution does not affect the solubility of an additional component. In real systems, the types of additional components, their structural transformations, and their associated non-ideal interactions influence the solubility limit. Non-ideal interactions can lead to short- or long-range ordering that decreases the overall configurational entropy. Due to the ionic-covalent nature of oxides, this ordering is the norm, not the exception. In the limited cases where mixing is ideal, charge coupled substitutions can work to influence overall configurational entropy contributions due to unique crystallographic sites. Long-range ordering can be minimized by mixing oxide components that have similar charge or are isostructural. Most excitingly, is the realization that surface energies will drastically affect the stability of oxide polymorphs and solubility limits. Thus, nano-materials are an interesting and novel approach that will vastly extend the HEO engineering space. As one can see, there are many avenues for the design and development of “HEOs” that thermodynamics will allow, even though they all may not be driven explicitly by entropy.

Filippo Masi, I. Stefanou, P. Vannucci et al.

M. Bianchini, Jingyang Wang, R. Clément et al.

Nayeli A. Rodríguez-Briones, Daniel K. Park

This work introduces an approach rooted in quantum thermodynamics to enhance sampling efficiency in quantum machine learning (QML). We propose conceptualizing quantum supervised learning as a thermodynamic cooling process. Building on this concept, we develop a quantum refrigerator protocol that enhances sample efficiency during training and prediction without the need for Grover iterations or quantum phase estimation. Inspired by heat-bath algorithmic cooling protocols, our method alternates entropy compression and thermalization steps to decrease the entropy of qubits, increasing polarization toward the dominant bias. This technique minimizes the computational overhead associated with estimating classification scores and gradients, presenting a practical and efficient solution for QML algorithms compatible with noisy intermediate-scale quantum devices.