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• The Gibbs-Duhem relation was proved to be followed by both the equilibrium and the non-equilibrium thermodynamics. • A TEP incorporating the constraints from both fluxes and forces was proposed. • The present model can describe not only the Soret effect but also the Dufour effect. The dependencies of fluxes and forces were paid close attention to the phenomenological theory of Onsager. But in such a case, it seems that the Onsager's reciprocal relations are not necessarily fulfilled. In this work, the problem of thermo-diffusion was chosen as an example and a combination of the first and the second law of thermodynamics was adopted to describe the reversible and the irreversible process. Accordingly, the Gibbs–Duhem relation was found to be followed by not only the equilibrium but also the non-equilibrium thermodynamics, i.e., the dependency of forces needs to be considered during the derivation of evolution equations. After that, a comparative study between the previous thermodynamic extremal principle (TEP) incorporating only the constraint from fluxes and the present TEP incorporating the constraints from both fluxes and forces was carried out. For the former, the well-known Dufour effect cannot be described, whereas, for the latter, both the well-known Soret effect and the Dufour effect can be predicted. Furthermore, the phenomenological equations were uniquely determined using the present TEP, and Onsager's reciprocal relations were found to be followed, thus solving the problem of the n -fold arbitrariness for the kinetic coefficients pointed out previously. The present work not only extends the TEP to non-isothermal thermodynamics but also might provide guidance for modeling dissipation systems with constraints from both fluxes and forces. [Display omitted] [ABSTRACT FROM AUTHOR]

During collective invasion in 3D, cohesive cellular tissues migrate within a fibrous extracellular matrix (ECM). This process requires significant remodeling of the ECM by cells, notably proteolysis at the cell–ECM interface by specialized molecules. Motivated by this problem, we develop a theoretical framework to study the dynamics of a fluid inclusion (modeling the cellular tissue) embedded in an elastic matrix (the ECM), which undergoes surface degradation/deposition. To account for the active nature of this process, we develop a continuum theory based on irreversible thermodynamics, leading to a kinetic relation for the degradation front that locally resembles the force–velocity relation of a molecular motor. We further study the effect of mechanotransduction on the stability of the cell–ECM interface, finding a variety of self-organized dynamical patterns of collective invasion. Our work identifies ECM proteolysis as an active process possibly driving the self-organization of cellular tissues. [ABSTRACT FROM AUTHOR]

A recent report from Jan Dlugosz University in Czestochowa, Poland discusses the use of Peusner's network thermodynamics (PNT) to describe membrane transport and energy conversion in membrane processes. The researchers developed a procedure to transform the Kedem-Katchalsky (K-K) equations for the transport of electrolytic solutions through a membrane to the Kedem-Katchalsky-Peusner (K-K-P) equations based on the PNT formalism. The study focused on a membrane used for hemodialysis and aqueous NaCl solutions. The researchers used the transformed equations to calculate coupling coefficients and dissipative energy flux, providing insights into the energy conversion of transport processes in the membrane system. [Extracted from the article]

We consider the framework of transfer-entropy-regularized Markov decision process (TERMDP) in which the weighted sum of the classical state-dependent cost and the transfer entropy from the state random process to the control input process is minimized. Although TERMDPs are generally formulated as nonconvex optimization problems, an analytical necessary optimality condition can be expressed as a finite set of nonlinear equations, based on which an iterative forward–backward computational procedure similar to the Arimoto–Blahut algorithm is developed. It is shown that every limit point of the sequence generated by the proposed algorithm is a stationary point of the TERMDP. Applications of TERMDPs are discussed in the context of networked control systems theory and nonequilibrium thermodynamics. The proposed algorithm is applied to an information-constrained maze navigation problem, whereby we study how the price of information qualitatively alters the optimal decision polices. [ABSTRACT FROM AUTHOR]

We consider damped stochastic systems in a controlled (time varying) potential and study their transition between specified Gibbs-equilibria states in finite time. By the second law of thermodynamics, the minimum amount of work needed for the transition from one equilibrium state to another is the difference between the Helmholtz free energy of the two states and can only be achieved by a reversible (infinitely slow) process. The minimal gap between the work needed in a finite-time transition and the work during a reversible one, turns out to equal the square of the optimal mass transport (Wasserstein-2) distance between the two end-point distributions times the inverse of the duration needed for the transition. This result, in fact, relates nonequilibrium optimal control strategies (protocols) to gradient flows of entropy functionals via the Jordan–Kinderlehrer–Otto scheme. The purpose of this paper is to introduce ideas and results from the emerging field of stochastic thermodynamics in the setting of the classical regulator theory, and to draw connections and derive such fundamental relations from a control perspective in a multivariable setting. [ABSTRACT FROM AUTHOR]

The article focuses on ways in which order emerges from chaos in nature, despite the second law of thermodynamics, which states that a system in equilibrium tends toward chaos, and not the reverse. Nature rarely finds a perfect equilibrium, and the author states that even in chaos, there can be smaller pockets of equilibrium. The author discusses a theory for nonequilibrium thermodynamics, which would explain instances where apparent chaos leads to order.

Purpose: The purpose of this paper is to examine the effect of varying compaction pressure on magnetic properties of self-developed soft magnetic composite (SMC) cores. The change in shape of ferromagnetic hysteresis curves has – in turn – the impact on the values of hysteresis model parameters. The phenomenological GRUCAD model is chosen for description of hysteresis curves. Design/methodology/approach: Several cylinder-shaped cores have been made from a mixture of iron powder and suspense polyvinyl chloride using a hydraulic press with a form and a band with a thermocouple for controlling heat treatment conditions. The only varying parameter in the study is the compaction pressure. The magnetic properties of developed cores have been measured using a computer-acquisition card and LabView software. The obtained hysteresis curves are fitted to the equations of the phenomenological GRUCAD model. This description is compliant with the laws of irreversible thermodynamics. The variations of model parameters are presented as functions of compacting pressure. Findings: The compaction pressure has a significant impact on magnetic properties of self-developed SMC cores. The paper provides a number of charts useful for checking how the parameters of the hysteresis model are affected. Research limitations/implications: The present paper is limited to modelling symmetrical loops only. Description of more complex magnetization cycles is postponed to another, forthcoming paper. Practical implications: The GRUCAD hysteresis model may be a useful tool for the designers of magnetic circuits. Its parameters depend on the processing conditions (in this study – the compaction pressure) of the SMC cores. Originality/value: Modelling of magnetic properties of SMC cores has been carried so far using some well-known description like Preisach, Takács and Jiles–Atherton proposals. The GRUCAD model has a number of advantages, and it may be a useful alternative to the latter formalism. So far it has been used for description of hysteresis curves in conventional materials like non-oriented and grain-oriented electrical steels. In the present work, it is applied to novel SMC materials. [ABSTRACT FROM AUTHOR]

• By using nonequilibrium thermodynamics, the coupled nonlinear govering equations of the transient properties of hydrogels are derived with considering the correlation between mass diffusion and heat transportion. • The free energy of hydroagels is derived in the from of swelling of hydrogels plus with stretching the swollen hydrogels, insted of a combination of stretching polymer networks and mixing it with solvent. • The free energy in the new from has clearer and more reasonable physical meaning, and it is more suitable to use in the applications of hydrogels. • Numerical simulations are carried out a commonly used structure of hydrogels, which may provide guidance to the applications of hydrogels. A polymer network can imbibe copious amounts of water and swell, and the resulting state is known as a hydrogel. In many potential applications of hydrogels, such as ionic cables, stretchable conductors, and fire resistance materials, the properties of hydrogels may change in response to the environment stimuli. However, existing researches about the transient properties of hydrogels usually treat different physical processes (mass diffusion, heat transportation, electric conduction, etc.) separately, ignoring the fact that there exist correlations between them. In the present work, from the point of view of nonequilibrium thermodynamics, the coupled non-linear governing equations for the transient properties of hydrogels are derived. Instead of writing the free energy of hydrogels as a combination of the stretching of polymer networks and mixing with solvent, we derive the free energy in the form of swelling of hydrogels plus stretching of the swollen hydrogels, which is a function of water content and stretch ratio of hydrogels under external forces or constraints. Chemical potential and total deformation of polymer networks are the fundamental parameters to characterize hydrogel states in many previous research. These are hard to determine, and we are less interested in these parameters. The new form of free energy is more suitable to be used in the laboratory or for the application of hydrogels in real situations, and its physical meaning is clearer. At last, a numerical simulation of the drying process of a hydrogel film attached on a substrate is carried out based on the governing equations and free energy. The transient water content distribution, temperature profile and stress field are investigated, which may provide a guide to the diverse applications of hydrogels. [ABSTRACT FROM AUTHOR]

Abstract Ill-conditioning is drawback of global radial basis functions (RBFs) method. Local RBFs method has overcome this difficulty and has become popular as an alternative methodology. In this paper, we analyze local RBFs method to solve singularly perturbed linear convection–diffusion problems. In some articles, it is investigated numerically but our aim is mainly to prove stability, consistency and convergence of local RBF method for boundary layer problems. It is known that the approximate error bound of Local RBFs method depends on two factors, Local density of knots, h, and the shape parameter, c. It is proven that this method is first order consistent. for verification, an unsteady Magnetohydrodynamic (MHD) free convective heat and mass transfer flow with Thermophoresis past a radiate inclined permeable plate in the presence of variable chemical reaction and temperature dependent viscosity is considered. Additionally some mathematical test problems are approximated. Numerical results reveal that the proposed method is accurate than upwind finite difference method. The optimal shape parameter strategy will also be utilized to approximate significant solutions. [ABSTRACT FROM AUTHOR]

Researchers from the Federal University of ABC in Sao Paulo, Brazil have published a new study on magnetic resonance. The study focuses on quantum thermodynamics, which aims to extend non-equilibrium stochastic thermodynamics to small quantum systems. The researchers highlight the importance of these investigations in relation to the advancements in quantum technological devices. The study provides an overview of concepts in quantum thermodynamics and discusses test-of-principles experiments using nuclear magnetic resonance techniques. The full article can be accessed for free through the provided link. [Extracted from the article]

A coupled finite strain chemo-transport-mechanical formulation with trapping is here proposed to extend a previous work set in the realm of small strain theory in continuum mechanics. The theory is rooted in non-equilibrium rational thermodynamics. The kinematics is based on a multiplicative decomposition of the deformation gradient to account for swelling and shrinking, thermal, elastic and inelastic contributions. Mass balance laws and balance of linear and angular momentum, as well as the laws of thermodynamics for a convecting body, are directly formulated in their material description, after specifications of some standard transformation rules between current and reference configuration. Thermodynamic restrictions are identified based on the functional dependence of the referential Helmholtz free energy density, which is chosen as the thermodynamic potential, and further subjected to a constitutive additive decomposition. Constitutive prescriptions for the chemical potentials, referential heat and mass fluxes, chemical kinetics and the generalized heat equation lead to the establishment of the governing equations. The theoretical framework is complemented by numerical simulations, highlighting the potential of the proposed formulation in multi-physics applications. [ABSTRACT FROM AUTHOR]

Granular materials are now known to be an illustration of complex materials as they display emergent macroscopic properties when loaded. An initially homogenous response can bifurcate into a heterogeneous one with the appearance of a rich variety of structured kinematical patterns. The shear banding that ensues illustrates a symmetry-breaking transition with multiple choices of macroscopic behaviours, a common feature of dynamical complex systems. Even though the phenomenon has been studied for decades, this regime transition remains mostly mysterious in geomaterials, with no convincing arguments that could link it to the underlying microscopic mechanisms. The paper investigates this issue by invoking the fundamental minimum entropy production theorem established by Prigogine in the past century to seek any connection with the second-order work theory in the mechanics of failure. A general equation linking the derivatives of the entropy of a mechanical system to the second-order work is thus inferred, which leads to a thermodynamic interpretation of bifurcations in the failure behaviour of granular materials under a given loading. This is verified through discrete element simulations that highlight the fundamental role played by the elastic energy stored within a granular material before a bifurcation occurs, which also corresponds to a minimization of the entropy production. The analysis suggests a new interpretation of the intriguing shear banding phenomenon as a bifurcation with the emergence of ordered dissipative structures germane to nonequilibrium thermodynamics of open systems. [ABSTRACT FROM AUTHOR]

The purpose of this work is the development of a framework for the formulation of geometrically non-linear inelastic chemomechanical models for a mixture of multiple chemical components diffusing among multiple transforming solid phases. The focus here is on general model formulation. No specific model or application is pursued in this work. To this end, basic balance and constitutive relations from non-equilibrium thermodynamics and continuum mixture theory are combined with a phase-field-based description of multicomponent solid phases and their interfaces. Solid phase modeling is based in particular on a chemomechanical free energy and stress relaxation via the evolution of phase-specific concentration fields, order-parameter fields (e.g., related to chemical ordering, structural ordering, or defects), and local internal variables. At the mixture level, differences or contrasts in phase composition and phase local deformation in phase interface regions are treated as mixture internal variables. In this context, various phase interface models are considered. In the equilibrium limit, phase contrasts in composition and local deformation in the phase interface region are determined via bulk energy minimization. On the chemical side, the equilibrium limit of the current model formulation reduces to a multicomponent, multiphase, generalization of existing two-phase binary alloy interface equilibrium conditions (e.g., KKS). On the mechanical side, the equilibrium limit of one interface model considered represents a multiphase generalization of Reuss-Sachs conditions from mechanical homogenization theory. Analogously, other interface models considered represent generalizations of interface equilibrium conditions consistent with laminate and sharp-interface theory. In the last part of the work, selected existing models are formulated within the current framework as special cases and discussed in detail. [ABSTRACT FROM AUTHOR]

We study impact of inertia on directed transport of a Brownian particle under non-equilibrium conditions: the particle moves in a one-dimensional periodic and symmetric potential, is driven by both an unbiased time-periodic force and a constant force, and is coupled to a thermostat of temperature T . Within selected parameter regimes this system exhibits negative mobility, which means that the particle moves in the direction opposite to the direction of the constant force. It is known that in such a setup the inertial term is essential for the emergence of negative mobility and it cannot be detected in the limiting case of overdamped dynamics. We analyse inertial effects and show that negative mobility can be observed even in the strong damping regime. We determine the optimal dimensionless mass for the presence of negative mobility and reveal three mechanisms standing behind this anomaly: deterministic chaotic, thermal noise induced and deterministic non-chaotic. The last origin has never been reported. It may provide guidance to the possibility of observation of negative mobility for strongly damped dynamics which is of fundamental importance from the point of view of biological systems, all of which in situ operate in fluctuating environments. [ABSTRACT FROM AUTHOR]

For more information on this research see: Investigation of non-equilibrium separation time on the partitioning of cephalexin in an aqueous two-phase system composed of glucose and acetonitrile. Keywords: Acetonitriles; Amides; Antibiotics; Beta-Lactam Antibiotics; Cephalexin Therapy; Cephalosporins; Health and Medicine; Nitriles; Organic Chemicals; Physics; Thermodynamics EN Acetonitriles Amides Antibiotics Beta-Lactam Antibiotics Cephalexin Therapy Cephalosporins Health and Medicine Nitriles Organic Chemicals Physics Thermodynamics 1449 1449 1 07/31/23 20230804 NES 230804 2023 AUG 4 (NewsRx) -- By a News Reporter-Staff News Editor at Drug Week -- Investigators publish new report on thermodynamics. [Extracted from the article]

An adaptive dynamic surface control method using nonlinear feedback is proposed for controlling the uncertain Genesio-Tesi chaotic system. The feature of the nonlinear feedback technique lies in that the feedback gains self-adjust under different amplitudes of system states. Based on the dynamic surface control technique, the complexity explosion problem existing in the backstepping-based chaotic controllers is circumvented. Moreover, the closed-loop stability is guaranteed with rigorous mathematical proof using Lyapunov stability theorem. Comparative results are given to verify the effectiveness and advantage of the proposed method with comparison to the existing linear feedback control. [ABSTRACT FROM AUTHOR]

This paper describes the most advanced results obtained in the context of fluid dynamic simulations of high-enthalpy flows using detailed state-to-state air kinetics. Thermochemical non-equilibrium, typical of supersonic and hypersonic flows, was modeled by using both the accurate state-to-state approach and the multi-temperature model proposed by Park. The accuracy of the two thermochemical non-equilibrium models was assessed by comparing the results with experimental findings, showing better predictions provided by the state-to-state approach. To overcome the huge computational cost of the state-to-state model, a multiple-nodes GPU implementation, based on an MPI-CUDA approach, was employed and a comprehensive code performance analysis is presented. Both the pure MPI-CPU and the MPI-CUDA implementations exhibit excellent scalability performance. GPUs outperform CPUs computing especially when the state-to-state approach is employed, showing speed-ups, of the single GPU with respect to the single-core CPU, larger than 100 in both the case of one MPI process and multiple MPI process. [ABSTRACT FROM AUTHOR]

The extracellular matrix (ECM) of a solid tumor not only affords scaffolding to support tumor architecture and integrity but also plays an essential role in tumor growth, invasion, metastasis, and therapeutics. In this paper, a non-equilibrium thermodynamic theory is established to study the chemo-mechanical behaviors of tumor ECM, which is modeled as a poroelastic polyelectrolyte consisting of a collagen network and proteoglycans. By using the principle of maximum energy dissipation rate, we deduce a set of governing equations for drug transport and mechanosensitive enzymatic degradation in ECM. The results reveal that osmosis is primarily responsible for the compression resistance of ECM. It is suggested that a well-designed ECM degradation can effectively modify the tumor microenvironment for improved efficiency of cancer therapy. The theoretical predictions show a good agreement with relevant experimental observations. This study aimed to deepen our understanding of tumor ECM may be conducive to novel anticancer strategies. [ABSTRACT FROM AUTHOR]

Higher-order cell-centered multi-material hydrodynamics (HD) and parallel node-centered radiation transport (RT) schemes are combined self-consistently in three-temperature (3T) radiation hydrodynamics (RHD) code TRHD (Sijoy and Chaturvedi, 2015) developed for the simulation of intense thermal radiation or high-power laser driven RHD. For RT, a node-centered gray model implemented in a popular RHD code MULTI2D (Ramis et al., 2009) is used. This scheme, in principle, can handle RT in both optically thick and thin materials. The RT module has been parallelized using message passing interface (MPI) for parallel computation. Presently, for multi-material HD, we have used a simple and robust closure model in which common strain rates to all materials in a mixed cell is assumed. The closure model has been further generalized to allow different temperatures for the electrons and ions. In addition to this, electron and radiation temperatures are assumed to be in non-equilibrium. Therefore, the thermal relaxation between the electrons and ions and the coupling between the radiation and matter energies are required to be computed self-consistently. This has been achieved by using a node-centered symmetric-semi-implicit (SSI) integration scheme. The electron thermal conduction is calculated using a cell-centered, monotonic, non-linear finite volume scheme (NLFV) suitable for unstructured meshes. In this paper, we have described the details of the 2D, 3T, non-equilibrium, multi-material RHD code developed with a special attention to the coupling of various cell-centered and node-centered formulations along with a suite of validation test problems to demonstrate the accuracy and performance of the algorithms. We also report the parallel performance of RT module. Finally, in order to demonstrate the full capability of the code implementation, we have presented the simulation of laser driven shock propagation in a layered thin foil. The simulation results are found to be in good agreement with the known solutions of RHD problems. [ABSTRACT FROM AUTHOR]

In many actual technological problems the system response is dictated by multi-physics events, which occur at different space–time-scales. Energy storage systems or active polymers are two illustrative real-life applications: they involve diffusion of chemically active species concurrent to mechanical deformations that take place in the same spatial domain. An abundant literature exists nowadays for this class of problems. There are, though, several major applications in which the motion of species is confined on advecting surfaces. The transport along membranes which advect and chemically respond only after getting into contact with an obstacle is a classical problem in cell mechanobiology or coatings, for instance. Modeling and simulations for such a class of problems is thoroughly investigated in the present note. [ABSTRACT FROM AUTHOR]

We develop a framework to investigate thermal creep and annealing in finite domains, where the climb motion of discrete dislocations is coupled to the diffusion of a continuum vacancy field. The model is first formulated in a continuum finite-deformation setting. All governing equations and boundary conditions are obtained from a unified irreversible thermodynamics principle. The resulting model couples a mechanical boundary value problem (BVP), a vacancy diffusion BVP, and the climb and glide motion of the discrete dislocation network within the crystal. The framework is then linearized for implementation in three-dimensional (3D) discrete dislocation dynamics (DDD) simulations for arbitrary anisotropic crystals. A solution scheme is developed based on the superposition principle, which is imposed weakly on the dislocation network to obtain a Galerkin solution for the nodal climb velocities. The framework includes diffusional (Nabarro–Herring) creep deformation as well as dislocation creep by climb-assisted-glide. The method is applied to simulate the annealing of vacancy loops in Al, with good agreement to experimental measurements by Silcox and Hirsch (1959). We further consider the effects of annealing under stress, and of the proximity of the vacancy loops to loaded and free boundaries Simulations in polycrystalline materials are carried out to highlight the effects of the grain size on dislocation climb and vacancy loop annealing. The method is also applied to estimate the creep rate due to climb-assisted glide of jogged-screw dislocations in γ -TiAl, and results are compared to experiments by Viswanathan et al. (1999). Finally, we discuss the effects of uniaxial and hydrostatic stresses on the two diffusive deformation pathways of the material, namely Nabarro–Herring creep and dislocation climb. [ABSTRACT FROM AUTHOR]

The Clausius-Duhem Inequality has been widely adopted to model the coupled Thermo-Hydro-Mechanical-Chemical processes. However, this paper points out that when modelling a reacting system, the Clausius-Duhem Inequality may hide the reaction mechanism and reaction type if the reaction changes the solid, and it may generate imprecise constitutive result if the reaction occurs within the fluid without changing the solid. To overcome these challenges, this paper proposed a novel non-equilibrium thermodynamics approach to model the multiphysics coupling processes with reactive dissolution. The new approach focuses on the Helmholtz free energy change in a dissolution process by quantifying the entropy production with the knowledge from non-equilibrium thermodynamics. A new concept, solid affinity, is introduced to give a better description of Helmholtz free energy change due to reactive dissolution. The coupled Thermo-Hydro-Mechanical-Chemical equations with reactive dissolution are derived by this approach. A numerical simulation is presented to show the role of quartz dissolution. [ABSTRACT FROM AUTHOR]

We study the nonequilibrium dynamics of two-component bosonic atoms in a one-dimensional optical lattice in the presence of spin-orbit coupling. In the Mott-insulating regime, the two-component bosonic system at unity filling can be described by the quantum spin X X Z model. The atoms are initially prepared in their lower spin states. The system becomes out of equilibrium by suddenly introducing spin-orbit coupling to the atoms. The system shows the relaxation and nonstationary dynamics, respectively, in the different interaction regimes. We find that the time average of magnetization is useful to characterize the many-body dynamics. The effects of even and odd numbers of sites are discussed. Our result sheds light on nonequilibrium dynamics due to the interplay between spin-orbit coupling and atomic interactions. [ABSTRACT FROM AUTHOR]

We establish a nonequilibrium scaling regime in the short-time evolution of one-dimensional interacting open quantum systems subject to a generic heating mechanism. This dynamical regime is characterized by uncompensated phonon production and a superdiffusive, universal scaling of quasiparticle lifetimes with momentum ~q-5/3, distinct from the finite- and zero-temperature cases. It is separated from a high-momentum regime by a time-dependent scale fading out as q0(t) ~ t-4/5. In the latter region we observe thermalization to an effective time-dependent equilibrium with linearly increasing temperature. By mapping out the dynamical phase diagram and computing the dynamical structure factor within an open-system Keldysh functional integral approach, we show how these predictions can be explored in cold-atom experiments by means of Bragg spectroscopy. [ABSTRACT FROM AUTHOR]

We investigate the nonequilibrium dynamics of the bosonic Hubbard model starting from inhomogeneous superfluid or Mott insulator initial states using the truncated Wigner approximation (TWA). We find that the relaxation of the system develops in two steps for sufficiently large interaction strengths: after a fast relaxation the system gets caught in metastable prethermalized states that precede the true equilibrium state. We find that the lifetime of these prethermalized states increases by several orders of magnitude as we increase the on-site interaction strength beyond a threshold value. We show that the emergence of long-lived metastable states in the quantum dynamics is associated with an ergodic (active) to nonergodic (inactive) dynamical phase transition in the ensemble of classical trajectories that contribute to the semiclassical limit. This dynamical phase transition, which is very similar to that found in different classical models of glasses, is closely related to the dynamic heterogeneity of the classical relaxation. [ABSTRACT FROM AUTHOR]

We study the nonequilibrium steady state arising from the interplay between coherent and dissipative dynamics in strongly interacting Rydberg gases using a recently introduced variational method [H. Weimer. Phys. Rev. Lett. 114. 040402 (2015)]. We give a detailed discussion of the properties of this approach and we provide a comparison with methods related to the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy. We find that the variational approach offers some intrinsic advantages and we also show that it is able to explain the experimental results obtained in an ultracold Rydberg gas on a quantitative level. [ABSTRACT FROM AUTHOR]

We study the relaxation and damping dynamics of an ultracold, but not quantum degenerate, gas consisting of dipolar particles. These simulations are performed using a direct simulation Monte Carlo method and employing the highly anisotropic differential cross section of dipoles in the Wigner threshold regime. We find that both cross-dimensional relaxation and damping of breathing modes occur at rates that are strongly dependent on the orientation of the dipole moments relative to the trap axis. The relaxation simulations are in excellent agreement with recent experimental results in erbium. The results direct our interest toward a less explored regime in dipolar gases where interactions are dominated by collision processes rather than mean-field interactions. [ABSTRACT FROM AUTHOR]

We propose a scheme for a quantum thermal machine made by atoms interacting with a single nonequilibrium electromagnetic field. The field is produced by a simple configuration of macroscopic objects held at thermal equilibrium at different temperatures. We show that these machines can deliver all thermodynamic tasks (cooling, heating, and population inversion) by establishing quantum coherence with the body on which they act. Remarkably, this system allows these machines to reach efficiencies at maximum power very close to the Carnot limit, which is much more than in existing models. Our findings offer a paradigm for efficient quantum energy flux management, and can be relevant for both experimental and technological purposes. [ABSTRACT FROM AUTHOR]

Conventional shape memory alloys (SMAs) exhibit an approximately linear relationship between the critical stresses of martensite transformation (MT) and ambient temperature (Clausius-Clapeyron relationship). Meanwhile, depending on the sign of entropy difference between the parent and martensite phases, these alloys behavior either a conventional or an inverse elastocaloric effect which originates from the latent heat release/absorption during stress-induced MT. Recently, MT with a non-monotonic Clausius-Clapeyron relationship (denotes as anomalous MT) and an elastocaloric switching effect (changes from the inverse elastocaloric effect at relatively low temperature to the conventional elastocaloric effect at relatively high temperature) were reported in CoCr-based Heusler-type SMAs. In this paper, to understand and quantitatively describe these new phenomena, a two-scale thermo-mechanically coupled constitutive model is constructed. In the mesoscopic scale, the fine twinned structure and the potential correspondent variant pairs of martensite phase are analyzed based on the crystallographic symmetry and the geometrically nonlinear theory of MT. The classical Debye's model is employed to describe the lattice and electronic heat capacities of the parent and martensite phases; while, a Monte Carlo simulation for the three-dimensional (3D) Ising's model is performed and a scaling law for the magnetic heat capacity of parent phase is proposed. Then, a new constitutive model is established based on the fundamental laws of irreversible thermodynamics to describe the non-isothermal stress-induced MT between parent and martensite phases. To consider the thermo-mechanical interactions between the parent phase and correspondent martensite variant pairs, each variant pair is regarded as an inhomogeneous inclusion with a mobile interface and embedded in the parent phase. With the help of interfacial operator, the thermodynamic driving force of MT is derived from the constructed Helmholtz free energy and dissipative inequality. Internal heat generation originated from the thermo-elasticity, inelastic deformation dissipation and latent heat is derived from the conservation law of energy. In the macroscopic scale, the thermo-mechanical response of SMA specimen is obtained by solving the equations of force balance, deformation compatibility, and thermodynamic equilibrium through the full-field calculation and mean-field approximation. Finally, the proposed model is verified by comparing the predictions with the experiments. It can be found that the anomalous MT and elastocaloric switching effect of CoCrAlSi SMA can be well captured by the proposed model. [ABSTRACT FROM AUTHOR]

Yin and Radzihovsky [X. Yin and L. Radzihovsky, Phys. Rev. A 88, 063611 (2013)] recently developed a self-consistent extension of a Bogoliubov theory, in which the condensate number density nc is treated as a mean field that changes with time, in order to analyze a JILA experiment by Makotyn et al. [P. Makotyn et al., Nat. Phys. 10, 116 (2014)] on a 85Rb Bose gas following a deep quench to a large scattering length. We apply this theory to construct a closed set of equations that highlight the role of nc, which is to induce an effective interaction between quasiparticles. We show analytically that such a system supports a steady state characterized by a constánt condensate density and a steady but periodically changing momentum distribution, whose time average is described exactly by the generalized Gibbs ensemble. We discuss how the nc-induced effective interaction, which cannot be ignored on the grounds of the adiabatic approximation for modes near the gapless Goldstone mode, can significantly affect condensate populations and Tan's contact for a Bose gas that has undergone a deep quench. [ABSTRACT FROM AUTHOR]

The paper deals with the mechanism of particle creation in the framework of irreversible thermodynamics. The second order nonequilibrium thermodynamical prescription of Israel and Stewart has been presented with particle creation rate, treated as the dissipative effect. In the background of a flat Friedmann- Robertson-Walker (FRW) model, we assume the nonequilibrium thermodynamical process to be isentropic so that the entropy per particle does not change and consequently the dissipative pressure can be expressed linearly in terms of the particle creation rate. Here the dissipative pressure behaves as a dynamical variable having a nonlinear inhomogeneous evolution equation and the entropy flow vector satisfies the second law of thermodynamics. Further, using the Friedmann equations and by proper choice of the particle creation rate as a function of the Hubble parameter, it is possible to show (separately) a transition from the inflationary phase to the radiation era and also from the matter dominated era to late time acceleration. Also, in analogy to analytic continuation, it is possible to show a continuous cosmic evolution from inflation to late time acceleration by adjusting the parameters. It is found that in the de Sitter phase, the comoving entropy increases exponentially with time, keeping entropy per particle unchanged. Subsequently, the above cosmological scenarios have been described from a field theoretic point of view by introducing a scalar field having self-interacting potential. Finally, we make an attempt to show the cosmological phenomenon of particle creation as Hawking radiation, particularly during the inflationary era. [ABSTRACT FROM AUTHOR]

We formulate a theory of non-equilibrium statistical thermodynamics for ensembles of atoms or molecules. The theory is an application of Jaynes׳ maximum entropy principle , which allows the statistical treatment of systems away from equilibrium. In particular, neither temperature nor atomic fractions are required to be uniform but instead are allowed to take different values from particle to particle. In addition, following the Coleman–Noll method of continuum thermodynamics we derive a dissipation inequality expressed in terms of discrete thermodynamic fluxes and forces. This discrete dissipation inequality effectively sets the structure for discrete kinetic potentials that couple the microscopic field rates to the corresponding driving forces, thus resulting in a closed set of equations governing the evolution of the system. We complement the general theory with a variational meanfield theory that provides a basis for the formulation of computationally tractable approximations. We present several validation cases, concerned with equilibrium properties of alloys, heat conduction in silicon nanowires and hydrogen desorption from palladium thin films, that demonstrate the range and scope of the method and assess its fidelity and predictiveness. These validation cases are characterized by the need or desirability to account for atomic-level properties while simultaneously entailing time scales much longer than those accessible to direct molecular dynamics. The ability of simple meanfield models and discrete kinetic laws to reproduce equilibrium properties and long-term behavior of complex systems is remarkable. [ABSTRACT FROM AUTHOR]

We propose a scheme for driving a dimer of spatially separated qubits into a maximally entangled nonequilibrium steady state. A photon-mediated retarded interaction between the qubits is realized by coupling them to two tunnel-coupled leaky cavities where each cavity is driven by a coherent microwave tone. The proposed cooling mechanism relies on striking the right balance between the unitary and driven-dissipative dynamics of the qubit subsystem. We map the dimer to an effective transverse-field isotropic X Y model coupled to a nonequilibrium bath that can be suitably engineered through the choice of drive frequencies and amplitudes. We show that both singlet and triplet states can be obtained with remarkable fidelities. The proposed protocol can be implemented with a superconducting circuit architecture that was recently experimentally realized and paves the way to achieving large-scale entangled systems that are arbitrarily long lived. [ABSTRACT FROM AUTHOR]

We consider parameter estimations with probes being the boundary-driven or dissipated nonequilibrium steady states of X X Z spin-1/2 chains. The parameters to be estimated are the dissipation coupling and the anisotropy of the spin-spin interaction. In the weak-coupling regime we compute the scaling of the Fisher information, i.e., the inverse best sensitivity among all estimators, with the number of spins. We find superlinear scalings and transitions between the distinct isotropic and anisotropic phases. We also look at the best relative error, which decreases with the number of particles faster than the shot-noise only for the estimation of anisotropy. [ABSTRACT FROM AUTHOR]

Inspired by the Wald-Kodama entropy S = A/(4Geff) where A is the horizon area and Geff is the effective gravitational coupling strength in modified gravity with field equation Rμν-Rgμν/2 = 8πGeffTμν(eff), we develop a unified and compact formulation in which the Friedmann equations can be derived from thermodynamics of the Universe. The Hawking and Misner-Sharp masses are generalized by replacing Newton's constant G with Geff, and the unified first law of equilibrium thermodynamics is supplemented by a nonequilibrium energy dissipation term E which arises from the revised continuity equation of the perfect-fluid effective matter content and is related to the evolution of Geff. By identifying the mass as the total internal energy, the unified first law for the interior and its smooth transit to the apparent horizon yield both Friedmann equations, while the nonequilibrium Clausius relation with entropy production for an isochoric process provides an alternative derivation on the horizon. We also analyze the equilibrium situation Geff = G = constant, provide a viability test of the generalized geometric masses, and discuss the continuity/conservation equation. Finally, the general formulation is applied to the Friedmann-Robertson-Walker cosmology of minimally coupled f(R), generalized Brans-Dicke, scalar-tensor-chameleon, quadratic, f(R,G) generalized Gauss-Bonnet and dynamical Chern-Simons gravity. In these theories we also analyze the f(R)-Brans-Dicke equivalence, find that the chameleon effect causes extra energy dissipation and entropy production, geometrically reconstruct the mass ρm V for the physical matter content, and show the self-inconsistency of f(R,G) gravity in problems involving Geff. [ABSTRACT FROM AUTHOR]

Open quantum systems are studied from the thermodynamical point of view unifying the principle of maximum informational entropy and the hypothesis of relaxation times hierarchy. The result of the unification is a non-Markovian and local-in-time master equation that provides a direct connection for dynamical and thermodynamical properties of open quantum systems. The power of the approach is illustrated by the application to the damped harmonic oscillator and the damped driven two-level system, resulting in analytical expressions for the non-Markovian and nonequilibrium entropy and inverse temperature. [ABSTRACT FROM AUTHOR]

We contribute to a long-standing debate on the supposed failure of the fluctuation dissipation theorem (FDT) for the Davies master equation (DME), an important class of Lindblad quantum master equations, describing time-driven quantum systems weakly coupled to a heat bath. First we propose two simple and natural criteria on the driving which guarantee compatibility with the FDT. We show through our setting that, contrary to what is often stated in the literature, the DME is fully compatible with the FDT. We thus argue that the cause of the dispute lies in the adopted perturbation scheme, rather than in the Lindblad character of the master equation itself. We confirm our statement by proving that the Grabert master equation, first proposed by Grabert [Projection Operator Techniques in Nonequilibrium Statistical Mechanics (Springer, Berlin, 1982)] as an alternative linear dynamics fulfilling the FDT, is nothing else than the incriminated DME. Our criteria for the FDT can also be used in the analysis of the nonlinear thermodynamical master equation, first obtained in the Brownian motion limit [H. Grabert, Z. Phys. B 49, 161 (1982)] and later independently rediscovered and generalized on purely thermodynamic grounds [H. C. Öttinger, Europhys. Lett. 94, 10006 (2011)]. [ABSTRACT FROM AUTHOR]

We present a method for investigating nonequilibrium dynamics of an ultracold system that is initially at thermal equilibrium. Our procedure is based on the classical fields approximation and appropriately prepared initial state for antiferromagnetic condensate with fixed magnetization. As an application of the method, we investigate the influence of thermal fluctuations on the quantum phase transition from an antiferromagnetic to phase separated ground state in a spin-1 Bose-Einstein condensate of ultracold atoms. We find that at temperatures significantly lower than the critical condensation temperature Tc the scaling law for the number of created spin defects remains intact. [ABSTRACT FROM AUTHOR]

We theoretically investigate the effect of dissipation on multiphoton excitation of Rydberg atoms. The steady states and the dynamics are compared via two types of four-level excitation schemes with different dissipative paths of spontaneous emission. We find that in the case of strong Rydberg-Rydberg interaction, the schemes will settle in several different nonequilibrium steady states. The interesting aspect is that there exist the multistable steady states, which reveals the competition between interaction-induced nonlinearity and dissipation caused by spontaneous emission. A numerical simulation on the Rydberg population dynamics in the bistable region exhibits different features existing in the two schemes even with the same initial conditions, which accounts for the influence of the dissipation on the dynamics. [ABSTRACT FROM AUTHOR]

Nonequilibrium dynamics and effective thermalization are studied in a resonant tunneling scenario via multilevel Landau-Zener crossings. Our realistic many-body system, composed of two energy bands, naturally allows a separation of degrees of freedom. This gives access to an effective temperature and single- and two-body observables to characterize the delocalization of eigenstates and the nonequilibrium dynamics of our paradigmatic complex quantum system. [ABSTRACT FROM AUTHOR]

The study of nonequilibrium phenomena in correlated lattice systems has developed into one of the most active and exciting branches of condensed matter physics. This research field provides rich new insights that could not be obtained from the study of equilibrium situations, and the theoretical understanding of the physics often requires the development of new concepts and methods. On the experimental side, ultrafast pump-probe spectroscopies enable studies of excitation and relaxation phenomena in correlated electron systems, while ultracold atoms in optical lattices provide a new way to control and measure the time evolution of interacting lattice systems with a vastly different characteristic time scale compared to electron systems. A theoretical description of these phenomena is challenging because, first, the quantum-mechanical time evolution of many-body systems out of equilibrium must be computed and second, strong-correlation effects which can be of a nonperturbative nature must be addressed. This review discusses the nonequilibrium extension of the dynamical mean field theory (DMFT), which treats quantum fluctuations in the time domain and works directly in the thermodynamic limit. The method reduces the complexity of the calculation via a mapping to a self- consistent impurity problem, which becomes exact in infinite dimensions. Particular emphasis is placed on a detailed derivation of the formalism, and on a discussion of numerical techniques, which enable solutions of the effective nonequilibrium DMFT impurity problem. Insights gained into the properties of the infinite-dimensional Hubbard model under strong nonequilibrium conditions are summarized. These examples illustrate the current ability of the theoretical framework to reproduce and understand fundamental nonequilibrium phenomena, such as the dielectric breakdown of Mott insulators, photodoping, and collapse-and-revival oscillations in quenched systems. Furthermore, remarkable novel phenomena have been predicted by the nonequilibrium DMFT simulations of correlated lattice systems, including dynamical phase transitions and field-induced repulsion-to-attraction conversions. [ABSTRACT FROM AUTHOR]

We employ the holographic method to study fluctuations and dissipation of an n-dimensional moving mirror coupled to quantum critical theories in d spacetime dimensions. The bulk counterpart of the mirror with perfect reflection is a n+1-dimensional membrane in the Lifshitz geometry of d+1 dimensions. The motion of the mirror can be realized from the dynamics of the brane at the boundary of the bulk. The excited modes of the brane in the bulk render the mirror undergoing Brownian motion. For small displacement of the mirror, we derive the analytical results of the correlation functions and response functions. The dynamics of the mirror due to small fluctuations around the brane vacuum state in the bulk is found supraohmic so that after initial growth, the velocity fluctuations approach a saturated value at late time with a power-law behavior. On the contrary, in the Lifshitz black hole background, the mirror in thermal fluctuations shows that its relaxation dynamics becomes ohmic, and the saturation of velocity fluctuations is reached exponentially in time. Finally a comparison is made with the result of a moving mirror driven by free fields. [ABSTRACT FROM AUTHOR]

We derive the master equation that completely determines the time evolution of the density matrix of the Unruh-DeWitt detector in an arbitrary background geometry. We apply the equation to reveal a nonequilibrium thermodynamic character of de Sitter space. This generalizes an earlier study on the thermodynamic property of the Bunch-Davies vacuum that an Unruh-DeWitt detector staying in the Poincaré patch and interacting with a scalar field in the Bunch-Davies vacuum behaves as if it is in a thermal bath of finite temperature. In this paper, instead of the Bunch-Davies vacuum, we consider a class of initial states of scalar field, for which the detector behaves as if it is in a medium that is not in thermodynamic equilibrium and that undergoes a relaxation to the equilibrium corresponding to the Bunch-Davies vacuum. We give a prescription for calculating the relaxation times of the nonequilibrium processes. We particularly show that, when the initial state of the scalar field is the instantaneous ground state at a finite past, the relaxation time is always given by a universal value of half the curvature radius of de Sitter space. We expect that the relaxation time gives a nonequilibrium thermodynamic quantity intrinsic to de Sitter space. [ABSTRACT FROM AUTHOR]

Recently, concepts of topological phases of matter are extended to nonequilibrium systems, especially periodically driven systems. In this paper, we construct an example which shows nonequilibrium topological phase transitions using ultracold fermions in optical lattices. We show that the Rabi oscillation has the possibility to induce nonequilibrium topological phases which are classified into time-reversal-invariant topological insulators for a two-orbital model of alkaline-earth-metal atoms. Furthermore, we study the nonequilibrium topological phases using time-dependent Schrieffer-Wolff-type perturbation theory, and we obtain an analytical expression to describe the topological phase transitions from a high-frequency limit of external driving fields [ABSTRACT FROM AUTHOR]

In this paper, a thermomechanical constitutive model was developed for the time-dependent behaviors of the glass transition of amorphous networks. The model used multiple discrete relaxation processes to describe the distribution of relaxation times for stress relaxation, structural relaxation, and stress-activated viscous flow. A non-equilibrium thermodynamic framework based on the fictive temperature was introduced to demonstrate the thermodynamic consistency of the constitutive theory. Experimental and theoretical methods were developed to determine the parameters describing the distribution of stress and structural relaxation times and the dependence of the relaxation times on temperature, structure, and driving stress. The model was applied to study the effects of deformation temperatures and physical aging on the shape-memory behavior of amorphous networks. The model was able to reproduce important features of the partially constrained recovery response observed in experiments. Specifically, the model demonstrated a strain-recovery overshoot for cases programmed below T g and subjected to a constant mechanical load. This phenomenon was not observed for materials programmed above T g . Physical aging, in which the material was annealed for an extended period of time below T g , shifted the activation of strain recovery to higher temperatures and increased significantly the initial recovery rate. For fixed-strain recovery, the model showed a larger overshoot in the stress response for cases programmed below T g , which was consistent with previous experimental observations. Altogether, this work demonstrates how an understanding of the time-dependent behaviors of the glass transition can be used to tailor the temperature and deformation history of the shape-memory programming process to achieve more complex shape recovery pathways, faster recovery responses, and larger activation stresses. [ABSTRACT FROM AUTHOR]

In the context of ultracold atoms in multimode optical cavities, the appearance of a quantum-critical glass phase of atomic spins has been predicted recently. Due to the long-range nature of the cavity-mediated interactions, but also the presence of a driving laser and dissipative processes such as cavity photon loss, the quantum optical realization of glassy physics has no analog in condensed matter and could evolve into a "cavity glass microscope" for frustrated quantum systems out of equilibrium. Here we develop the nonequilibrium theory of the multimode Dicke model with quenched disorder and Markovian dissipation. Using a unified Keldysh path integral approach, we show that the defining features of a low-temperature glass, representing a critical phase of matter with algebraically decaying temporal correlation functions, are seen to be robust against the presence of dissipation due to cavity loss. The universality class, however, is modified due to the Markovian bath. The presence of strong disorder leads to an enhanced equilibration of atomic and photonic degrees of freedom, including the emergence of a common low-frequency effective temperature. The imprint of the atomic spin-glass physics onto the photon subsystem realizes a "photon glass" state and makes it possible to detect the glass state by standard experimental techniques of quantum optics. We provide an unambiguous characterization of the superradiant and glassy phases in terms of fluorescence spectroscopy, homodyne detection, and the temporal photon correlation function g(2)(r). [ABSTRACT FROM AUTHOR]

The interplay between interactions and decoherence in màny-body systems is of fundamental importance in quantum physics. In a step toward understanding this interplay, we obtain an exact analytic solution for the nonequilibrium dynamics of Ising models with arbitrary couplings (and therefore in arbitrary dimension) and subject to local Markovian decoherence. Our solution shows that decoherence significantly degrades the nonclassical correlations developed during coherent Ising spin dynamics, which relax much faster than predicted by treating decoherence and interactions separately. We also show that the competition of decoherence and interactions induces a transition from oscillatory to overdamped dynamics that is absent at the single-particle or mean-field level. These calculations are applicable to ongoing quantum information and emulation efforts using a variety of atomic, molecular, optical, and solid-state systems. In particular, we apply our results to the NIST Penning trapped-ion experiment and show that the current experiment is capable of producing entanglement amongst hundreds of quantum spins. [ABSTRACT FROM AUTHOR]

We derive a nonequilibrium fluctuation-dissipation relation for bosonic correlation functions from holography in the classical gravity approximation at strong coupling. This generalizes the familiar thermal fluctuation-dissipation relation in the absence of external sources. This also holds universally for any nonequilibrium state which can be obtained from a stable thermal equilibrium state in perturbative derivative (hydrodynamic) and amplitude (nonhydrodynamic) expansions. Therefore, this can provide a strong experimental test for the applicability of the holographic framework. We discuss how it can be tested in heavy-ion collisions. We also make a conjecture regarding multipoint holographic nonequilibrium Green's functions. [ABSTRACT FROM AUTHOR]

While the Gross-Pitaevskii equation is well established as the canonical dynamical description of atomic Bose-Einstein condensates (BECs) at zero temperature, describing the dynamics of BECs at finite temperatures remains a difficult theoretical problem, particularly when considering low-temperature, nonequilibrium systems in which depletion of the condensate occurs dynamically as a result of external driving. In this paper, we describe a fully time-dependent numerical implementation of a second-order, number-conserving description of finite-temperature BEC dynamics. This description consists of equations of motion describing the coupled dynamics of the condensate and noncondensate fractions in a self-consistent manner, and is ideally suited for the study of low-temperature, nonequilibrium, driven systems. The d-kicked-rotor BEC provides a prototypical example of such a system, and we demonstrate the efficacy of our numerical implementation by investigating its dynamics at finite temperature. We demonstrate that the qualitative features of the system dynamics at zero temperature are generally preserved at finite temperatures, and predict a quantitative finite-temperature shift of resonance frequencies which would be relevant for, and could be verified by, future experiments. [ABSTRACT FROM AUTHOR]