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Wolfgang Muschik

Publications and source records attributed to Wolfgang Muschik.

At least 19 recordsLinked to original sources
arXiv2026

Constitutive Settings with regard to Energy- and Entropy-Balances in Non-Equilibrium Thermodynamics: the Thermodynamical Verification

Constitutive equations have to be in agreement with the energy- and entropy- balances. For achieving that, the procedure of thermodynamical verification is introduced: Because heat flux and entropy flux as well as the time differentials of internal energy and entropy are not independent of each other, energy- and entropy-balances are connected with each other by so-called internal settings laying down the theoretical frame of the applied material description which is characterized by additional constitutive settings.

physics.class-ph↗
arXiv2024

Second Law and its Amendment: the Axiom of No-reversible Directions -- Revisited

A toy-model is used for describing the steps achieving the no-reversible-direction axiom in a tutorial manner: i) choice of a state space results in the balance equations on state space which are linear in the process directions, ii) a reversible process direction cannot be generated by combination of non-reversible ones, iii) process directions which are in the kernel of the balance equations do not enter the entropy production. The Coleman-Mizel formulation of the second law and the Liu relations follow immediately.

cond-mat.stat-mech↗
arXiv2022

Phenomenological Non-Equilibrium Quantum Thermodynamics based on Modified von Neumann Equations

The wide-spread opinion is that original quantum mechanics is a reversible theory, but this statement is only true for undecomposed systems, that are those systems which sub-systems are out of consideration. Taking sub-systems into account, as it is by definition necessary for decomposed systems, the interaction Hamiltonians which are absent in undecomposed systems generate irreversibility. Thus, the following two-stage task arises: How to modify von Neumann's equation for undecomposed systems so that irreversibility appears, and how this modification affects decomposed systems ? The first step was already done and is repeated below, whereas the second step to formulate a quantum thermodynamics of decomposed systems is performed here by modifying the von Neumann equations of the sub-systems by a procedure wich is similar to that of Lindblad's equation, but different because the sub-systems interact with one another through partitions.

quant-ph↗
arXiv2020

Discrete Systems in Thermal Physics and Engineering -- A Glance from Non-Equilibrium Thermodynamics

Non-equilibrium processes in Schottky systems generate by projection onto the equilibrium subspace reversible accompanying processes for which the non-equilibrium variables are functions of the equilibrium ones. The embedding theorem which guarantees the compatibility of the accompanying processes with the non-equilibrium entropy is proved. The non-equilibrium entropy is defined as a state function on the non-equilibrium state space containing the contact temperature as a non-equilibrium variable. If the entropy production does not depend on the internal energy, the contact temperature changes into the thermostatic temperature also in non-equilibrium, a fact which allows to use temperature as a primitive concept in non-equilibrium. The dissipation inequality is revisited, and an efficiency of generalized cyclic processes beyond the Carnot process is achieved.

cond-mat.stat-mech↗
arXiv2020

Phenomenological Quantum Thermodynamics of Closed Bipartite Schottky Systems

How to introduce thermodynamics to quantum mechanics ? Among from numerous possibilities of solving this task, the simple choice is here: The conventional von Neumann equation deals with a density operator whose probability weights are time independent. Because there is no reason apart from the reversible quantum mechanics that these weights have to be time independent, this constraint is waived, thus making possible to introduce thermodynamical concepts to quantum mechanics. %\textcolor{green}{ This procedure is similar to that of Lindblad's equation, but different on principle. %\textcolor{red}{ But beyond this simple starting-point, the applied thermodynamical concepts of discrete systems may perform a "source theory" for other versions of phenomenological quantum thermodynamics.

quant-ph↗
arXiv2019

Covariant Relativistic Non-Equilibrium Thermodynamics of Multi-Component Systems

Non-equilibrium and equilibrium thermodynamics of an interacting component in a relativistic multi-component system is discussed covariantly by exploiting an entropy identity. The special case of the corresponding free component is considered. Equilibrium conditions and especially the multi-component Killing relation of the 4-temperature are discussed. Two axioms characterize the mixture: additivity of the energy momentum tensors and additivity of the 4-entropies of the components generating those of the mixture. The resulting quantities of a single component and of the mixture as a whole, energy, energy flux, momentum flux, stress tensor, entropy, entropy flux, supply and production are derived. Finally, a general relativistic 2-component mixture is discussed with respect to their gravitation generating energy-momentum tensors.

gr-qc↗
arXiv2018

Concepts of Phenomenological Irreversible Quantum Thermodynamics I: Closed Undecomposed Schottky Systems in Semi-classical Description

If the von Neumann equation is modified by time dependent statistical weights, the time rate of entropy, the entropy exchange and production of a Schottky system are derived whose Hamiltonian does not contain the interaction with the system's environment. This interaction is semi-classically described by the quantum theoretical expressions of power- and entropy exchange.

quant-ph↗
arXiv2018

Second Law and Non-Equilibrium Entropy of Schottky Systems -- Doubts and Verification

Meixner's historical remark in 1969 "... it can be shown that the concept of entropy in the absence of equilibrium is in fact not only questionable but that it cannot even be defined...." is investigated from today's insight. Several statements --such as the three laws of phenomenological thermodynamics, the embedding theorem and the adiabatical uniqueness-- are used to get rid of non-equilibrium entropy as a primitive concept. In this framework, Clausius inequality of open systems can be derived by use of the defining inequalities which establish the non-equilibrium quantities contact temperature and non-equilibrium molar entropy which allow to describe the interaction between the Schottky system and its controlling equilibrium environment.

cond-mat.stat-mech↗
arXiv2018

Entropy Identity inducing Non-Equilibrium Thermodynamics of Relativistic Multi-Component Systems and their Newtonian Limits

Non-equilibrium and equilibrium thermodynamics of an interacting component in a special-relativistic multi-component system is discussed by use of an entropy identity. The special case of the corresponding free component is considered. Equilibrium conditions and especially the multi-component Killing relation of the 4-temperature are discussed. Two axioms characterize the mixture: additivity of the energy momentum tensors and of the 4-entropies of the components generating those of the mixture. The resulting quantities of a component and of the mixture, energy, energy flux, momentum flux, stress tensor, entropy, entropy flux, supply and production and their Newtonian limits in zeroth approximation are derived.

gr-qc↗
arXiv2017

Contact Temperature as an Internal Variable of Discrete Systems in Non-Equilibrium

State space and entropy rate of a discrete non-equilibrium system are shortly considered including internal variables and the contact temperature. The concept of internal variables in the context of non-equilibrium thermodynamics of a closed discrete system is discussed. The difference between internal variables and degrees of freedom are repeated, and different types of their evolution equations are mentioned in connection with Gérard A. Maugin's numerous papers on applications of internal variables. The non-equilibrium contact temperature is recognized as an internal variable and its evolution equation is presented.

physics.class-ph↗
arXiv2016

Non-Equilibrium Thermodynamics and Stochasticity, A Phenomenological Look on Jarzynki's Equality

The theory of phenomenological Non-equilibrium Thermodynamics is extended by includimg stochastic processes in order to account for recently derived thermodynamical relations such as the Jarzynski equality. Four phenomenological axioms are postulated resulting in a phenomenological interpretation of Jarzynski's equality. Especially, considering the class of Jarzynski processes Jarzynski's equality follows from the axiom that the statistical average of the exponential work is protocol independent.

nlin.CD↗
arXiv2015

Entropy Production and Equilibrium Conditions of General-Covariant Spin Systems

In generalizing the special-relativistic one-component version of Eckart's continuum thermodynamics to general-relativistic space-times with Riemannian or post-Riemannian geometry, we consider the entropy production and other themodynamical quantities such as the entropy flux and the Gibbs fundamental equation. We discuss equilibrium conditions in gravitational theories which are based on such geometries. In particular, thermodynamic implications of the non-symmetry of the energy-momentum tensor and the related spin balance equations are investigated, also for the special case of General Relativity.

gr-qc↗
arXiv2015

Entropy Production and Equilibrium Conditions in General-Covariant Continuum Physics

Starting out with an entropy identity, the entropy flux, the entropy production and the corresponding Gibbs and Gibbs-Duhem equations of general-covariant conti\-nuum thermodynamics are established. Non-dissipative materials and equilibria are investigated. It is proved that equilibrium conditions only put on material properties cannot generate equilibria, rather additionally, the Killing property of the 4-temperature is a necessary condition for space-times in which equilibria are possible.

gr-qc↗
arXiv2013

Jarzynski Equality and Irreversibility

Using methods of phenomenological non-equilibrium thermodynamics, the proof is performed that Jarzynski's equality is only valid in the reversible limit and that a conclusion to non-equilibrium inequalities concerning free energy and work is not possible and therefore not allowed.

math-ph↗
arXiv2013

Mathisson-Papapetrou Equations as Conditions for Compatibility of General Relativity and Continuum Physics

In continuum physics is presupposed that general-relativistic balance equations are valid which are created from the Lorentz-covariant ones by application of the equivalence principle. Consequently, the question arises, how to make these general-covariant balances compatible with Einstein's field equations. The compatibility conditions are derived by performing a modified Belinfante-Rosenfeld symmetrization for the non-symmetric and not divergence-free general-relativistic energy-momentum tensor. The procedure results in the Mathisson-Papapetrou equations.

gr-qc↗