Relationship between the thermodynamics of nonequilibrium state and the thermodynamics of nonequilibrium processes

The concept and equations of the thermodynamics of nonequilibrium state are compared with the postulates of linear thermodynamics of nonequilibrium processes. It is shown that all the four basic postulates can be obtained as consequences of the equations of the thermodynamics of nonequilibrium state. In the limiting case of small deviations from equilibrium, the thermodynamics of nonequilibrium state are reduced to linear thermodynamics of nonequilibrium processes.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 10–14, December, 1990.     

金属超微粒子-半导体薄膜的光学瞬态响应

利用飞秒脉冲激光和泵浦 探测技术测量了金属超微粒子 半导体复合薄膜Ａｇ-ＢａＯ的瞬态光学透过率随延迟时间的变化曲线，观察到了薄膜对光的吸收漂白现象，并在不到２ｐｓ时间内恢复．该现象是薄膜中金属超微粒子内费密能级附近电子被飞秒激光脉冲激发，产生非平衡电子而经历瞬态弛豫造成的．弛豫主要包括非平衡电子越过超微粒子和周围介质的界面位垒进入周围介质，以及非平衡电子同晶格和界面的散射两种过程．超微粒子粒径的差别会引起非平衡电子弛豫时间的差别 关键词：     

Hydrodynamic and Thermodynamic Nonequilibrium Effects around Shock Waves: Based on a Discrete Boltzmann Method

A shock wave that is characterized by sharp physical gradients always draws the medium out of equilibrium. In this work, both hydrodynamic and thermodynamic nonequilibrium effects around the shock wave are investigated using a discrete Boltzmann model. Via Chapman–Enskog analysis, the local equilibrium and nonequilibrium velocity distribution functions in one-, two-, and three-dimensional velocity space are recovered across the shock wave. Besides, the absolute and relative deviation degrees are defined in order to describe the departure of the fluid system from the equilibrium state. The local and global nonequilibrium effects, nonorganized energy, and nonorganized energy flux are also investigated. Moreover, the impacts of the relaxation frequency, Mach number, thermal conductivity, viscosity, and the specific heat ratio on the nonequilibrium behaviours around shock waves are studied. This work is helpful for a deeper understanding of the fine structures of shock wave and nonequilibrium statistical mechanics.     

Investigation of nonequilibrium hydroxyl emission spectra

Ultraviolet nonequilibrium OH emission spectra in flames are measured and analyzed. Spectra of nonequilibrium coefficients are recorded for an optically thin jet, and spectral absorption coefficients and electronic absorption band intensities are determined. Based on the developed mathematical radiative transfer model in a nonequilibrium radiating media, the OH contribution to radiative jet cooling is estimated, and practical applications of the nonequilibrium emission process to the development of optoelectronic systems of observation over aero carriers are considered.     

CH薄膜非平衡辐射烧蚀的特性

用一维多群辐射输运流体力学RDMG程序数值模拟研究了在神光-II黑腔辐射源条件下,非平衡辐射烧蚀CH薄膜的过程,给出了与平衡辐射烧蚀不同的烧蚀图像,得到了非平衡辐射烧蚀相关的数值定律。     

Size effect in the magnetic field dependence of nonequilibrium electron tunneling

The electron bottleneck in normal metal-insulator-metal tunnel junctions due to nonequilibrium effects has been investigated in the presence of a magnetic field. The observed results are due to a new geometrical size effect and are explained in an extension of our nonequilibrium theory.     

非平衡涨落问题的微观唯象分析理论(Ⅰ)——一种新的广义不可逆热力学理论与热涨落中涨落—耗散表示式的非平衡修正

本文给出非平衡涨落问题的微观唯象分析理论——非平衡涨落的统计学描述理论。该理论的基础是广义非平衡熵与描述涨落几率的爱因斯坦表示式的推广。通过计算求得刚体热传导中比能与热通量的非平衡涨落的二阶矩。导出对热涨落的通用涨落-耗散表示式的非平衡修正,同时发现该修正相当于固体电介质中的光子热输运与金属中电子热输运的数值修正。     

Semiclassical analysis of the nonequilibrium local polaron

A resonant level strongly coupled to a local phonon under nonequilibrium conditions is investigated. The nonequilibrium Hartree-Fock approximation is shown to correspond to approximating the steady state density matrix by delta functions at field values to which the local dynamics relaxes in a semiclassical limit. If multiple solutions exist, all are shown to make nonvanishing contributions to physical quantities: multistability does not exist. Departures from equilibrium are shown to produce decoherence, preventing the formation of a polaron feature in the spectral function. The formalism also applies to the nonequilibrium Kondo problem.     

高温超导体场致发射的非平衡效应

高温超导体场致发射时 ,非平衡状态将使电场在超导发射体内增加穿透深度 ,这将使其场发射性质发生改变。本文对高温超导体场致发射的非平衡状态进行了研究。     

Flicker Noise in a Locally Nonequilibrium Medium

A model implying that particles of a medium are subjected to external forces with a flicker noise spectrum has been proposed to describe fluctuations in locally nonequilibrium physical media. The Langevin equation with additional integral terms describing the action of the locally nonequilibrium medium has been derived. The spectral density of fluctuations of an electric current flowing in the locally nonequilibrium medium has been calculated. It has been found that this density in the low-frequency spectral range is flicker noise.     

Nonequilibrium Thermodynamics of Polymeric Liquids via Atomistic Simulation

The challenge of calculating nonequilibrium entropy in polymeric liquids undergoing flow was addressed from the perspective of extending equilibrium thermodynamics to include internal variables that quantify the internal microstructure of chain-like macromolecules and then applying these principles to nonequilibrium conditions under the presumption of an evolution of quasie equilibrium states in which the requisite internal variables relax on different time scales. The nonequilibrium entropy can be determined at various levels of coarse-graining of the polymer chains by statistical expressions involving nonequilibrium distribution functions that depend on the type of flow and the flow strength. Using nonequilibrium molecular dynamics simulations of a linear, monodisperse, entangled C₁₀₀₀H₂₀₀₂ polyethylene melt, nonequilibrium entropy was calculated directly from the nonequilibrium distribution functions, as well as from their second moments, and also using the radial distribution function at various levels of coarse-graining of the constituent macromolecular chains. Surprisingly, all these different methods of calculating the nonequilibrium entropy provide consistent values under both planar Couette and planar elongational flows. Combining the nonequilibrium entropy with the internal energy allows determination of the Helmholtz free energy, which is used as a generating function of flow dynamics in nonequilibrium thermodynamic theory.     

Nonlinear transport in far-from-equilibrium semiconductors

Summary Using a nonlinear transport theory, derived from the nonequilibrium statistical operator method, we obtain the equations that govern the evolution of the nonequilibrium state of a highly photoexcited direct-gap polar semiconductor, and its nonequilibrium mobility coefficient. It provides an analytic method that allows for a deep physical insight into the influence of the nonequilibrium irreversible evolution of the plasma in the semiconductor on its transport properties. We demonstrate that, under quite general conditions, the strong dependence of the momentum and energy relaxation times on the irreversible evolution of the macroscopic nonequilibrium state of the system results in the existence of a structured transient mobility,i.e. one with maxima and minima, with or without overshoot. A criterion for the occurrence of this structure is derived as well as several general properties of the ultrafast transient are discussed. The authors of this paper have agreed to not receive the proofs for correction.     

Time Evolution in Macroscopic Systems. II. The Entropy

The concept of entropy in nonequilibrium macroscopic systems is investigated in the light of an extended equation of motion for the density matrix obtained in a previous study. It is found that a time-dependent information entropy can be defined unambiguously, but it is the time derivative or entropy production that governs ongoing processes in these systems. The differences in physical interpretation and thermodynamic role of entropy in equilibrium and nonequilibrium systems is emphasized and the observable aspects of entropy production are noted. A basis for nonequilibrium thermodynamics is also outlined.     

Emission characteristics of hydrogen-oxygen flames

The emission spectra of hydrogen-oxygen flames are discussed. High temperature measurements of the radiative characteristics of the OH group in flames are described. The spectral absorption coefficients and the integral intensities of the hydroxyl bands are analyzed. A method for determining the nonequilibrium radiative cooling of hydrogen-oxygen flames using experimental data, their temperatures, and nonequilibrium coefficients is described and the results are examined.     

Effect of phonon decay processes on the formation of a phonon nonequilibrium signal in crystals with two two-level subsystems

The effect of phonon decay on the characteristic propagation time and shape of a phonon nonequilibrium signal in disordered crystals, including crystals containing inelastic phonon scattering centers, is studied theoretically. Attention is focused on slow processes, which are typical of yttrium-aluminum garnet solid solutions and erbium-doped aluminates. It is shown that the temperature dependence of the arrival time of a phonon nonequilibrium signal in these systems can be governed, to a considerable extent, by phonon-phonon interactions. The results of the theoretical studies are compared with experimental data on the propagation of weakly nonequilibrium thermal phonons in solid solutions of rare-earth yttrium-aluminum garnets and aluminates.     

Oscillatory nonequilibrium Nambu systems: the canonical-dissipative Yamaleev oscillator

We study the emergence of oscillatory self-sustained behavior in a nonequilibrium Nambu system that features an exchange between different kinetical and potential energy forms. To this end, we study the Yamaleev oscillator in a canonical-dissipative framework. The bifurcation diagram of the nonequilibrium Yamaleev oscillator is derived and different bifurcation routes that are leading to limit cycle dynamics and involve pitchfork and Hopf bifurcations are discussed. Finally, an analytical expression for the probability density of the stochastic nonequilibrium oscillator is derived and it is shown that the shape of the density function is consistent with the oscillator properties in the deterministic case.     

Supersonic flow of a nonequilibrium gas-discharge plasma around a body

The flow of a nonequilibrium gas-discharge plasma around a semicylindrical body is studied. The aim of the study is to see how a change in the degree of nonequilibrium of the incoming plasma changes the separation distance between a shock wave and the body. Experiments are carried out with a supersonic nozzle into which a semicylindrical body is placed. The inlet of the nozzle is connected to a shock tube. In the course of the experiment, electrodes built into the wall of the nozzle initiate a gas discharge in front of the body to produce an additional nonequilibrium ionization in the stationary incoming supersonic flow. The discharge parameters are selected such that the discharge raises the electron temperature and still minimizes heating of the gas. The degree of nonequilibrium of the flow varies with gas-discharge current. Diagnostics of the flow is carried out with a schlieren system based on a semiconductor laser. The system can record flow patterns at definite time instants after discharge initiation.     

Detection of multi-spin interaction of a quenched XY chain by the average work and the relative entropy

We investigate the nonequilibrium thermodynamics of a quenched XY spin chain with multi-spin interaction in a transverse field. The analytical expressions of both the average work and the relative entropy are obtained under different quenching parameters. The influences of the system parameters on the nonequilibrium thermodynamics are investigated.We find that at finite temperature the critical phenomenon induced by the multi-spin interaction and the external field can be revealed by the properties of the system nonequilibrium thermodynamics. In addition, our results indicate that the average work and the relative entropy can be used to detect both the existence and strength of the multi-spin interaction in the nonequlibrium system.     

Generating Functionals in Nonequilibrium Statistical Mechanics

The main ideas and methods of calculations within the framework of the generating functional technique are considered in a systematical way. The nonequilibrium generating functionals are defined as functional mappings of the nonequilibrium statistical operator and so appear to be dependent on a certain set of macroscopic variables describing the nonequilibrium state of the system. The boundary conditions and the differential equation of motion for the generating functionals are considered which result in an explicit expression for the nonequilibrium generating functionals in terms of the so-called coarse-grained generating functional being the functional mapping of the quasiequilibrium statistical operator. Various types of integral equations are derived for the generating functionals which are convenient to develop the perturbation theories with respect to either small interaction or small density of particles. The master equation for the coarse-grained generating functionals is obtained and its connection with the generalized kinetic equations for a set of macrovariables is shown. The derivation of the generalized kinetic equations for some physical systems (classical and quantum systems of interacting particles, the Kondo system) is treated in detail, with due regard for the polarization effects as well as the energy and momentum exchange between the colliding particles and the surrounding media.     

Quantum Thermodynamic Uncertainties in Nonequilibrium Systems from Robertson-Schrödinger Relations

Thermodynamic uncertainty principles make up one of the few rare anchors in the largely uncharted waters of nonequilibrium systems, the fluctuation theorems being the more familiar. In this work we aim to trace the uncertainties of thermodynamic quantities in nonequilibrium systems to their quantum origins, namely, to the quantum uncertainty principles. Our results enable us to make this categorical statement: For Gaussian systems, thermodynamic functions are functionals of the Robertson-Schrödinger uncertainty function, which is always non-negative for quantum systems, but not necessarily so for classical systems. Here, quantum refers to noncommutativity of the canonical operator pairs. From the nonequilibrium free energy, we succeeded in deriving several inequalities between certain thermodynamic quantities. They assume the same forms as those in conventional thermodynamics, but these are nonequilibrium in nature and they hold for all times and at strong coupling. In addition we show that a fluctuation-dissipation inequality exists at all times in the nonequilibrium dynamics of the system. For nonequilibrium systems which relax to an equilibrium state at late times, this fluctuation-dissipation inequality leads to the Robertson-Schrödinger uncertainty principle with the help of the Cauchy-Schwarz inequality. This work provides the microscopic quantum basis to certain important thermodynamic properties of macroscopic nonequilibrium systems.