惰性气体在固体中的扩散和释放理论

本文给出了一个描述在各种固体材料中离子注入的惰性气体的扩散和从表面释放的模型。在这个模型中,同时考虑了各种缺陷和辐照损伤与惰性气体原子的相互作用,根据这个模型,给出了一组描写惰性气体原子的扩散方程,并给出了这组方程的解析解。与实验测量比较表明,这个模型能很好地描写惰性气体从固体表面释放的特性。用最小二乘法将理论释放曲线拟合于实验释放曲线,从而给出一个确定各种陷阱中心的激活能和归一化浓度的方法。 关键词：     

Thermodynamics of Modified Chaplygin Gas and Tachyonic Field

Here we generalize the results of the work of Myung () in modified Chaplygin gas model and tachyonic field model. Here we have studied the thermodynamical behavior and the equation of state in terms of volume and temperature for both models. We have used the solution and the corresponding equation of state of our previous work (Chattopadhyay et al., Astrophys. Space Sci. 314:41, 2008). for tachyonic field model. We have also studied the thermodynamical stability using thermal equation of state for the tachyonic field model and have shown that there is no critical points during thermodynamical expansion. The determination of T _∗ due to expansion for the tachyonic field have been discussed by assuming some initial conditions. Here, the thermal quantities have been investigated using some reduced parameters.     

应用于金属固体的四参数通用状态方程

提出一种能精确考虑固体结合能的四参数通用状态方程, 并且在高压和膨胀区域都具有正确的行为, 不会出现物理上不正确的振荡现象. 新方程可以将Vinet方程和普遍化Lennard-Jones (GLJ) 方程作为特例包括于其中. 将新方程与文献中的典型方程应用于32种金属固体, 结果表明新方程在给出正确结合能数据的同时, 能够很好的拟合实验压缩数据. 结果还表明, 多数金属的相互作用具有短程相互作用的性质, 但是结合能较大相互作用的强度较强.     

Positronium in molecular substances

The progress of research into the behavior of the positronium in molecular substances in the last several years is reviewed. The Ps atom can be treated as a solute in a liquid. The repulsive exchange force is the dominant force which reacts against the van der Waals attractive force. One of the most useful general relationships found is the one between the pick-off quenching rate and the surface tension of the liquid. The pick-off quenching rate is found, in general, to be an additive property of the functional groups of a molecule. The quenching of theo-Ps atom by an active quenching agent in an inert solvent has been found to be primarily diffusion controlled. Some deviations from the simple Arrhenius equation have been found. For gases, more theoretical work on the collision problems of Ps with atoms or molecules is needed. For amorphous molecular solids, it is likely that the property of pick-off quenching ofo-Ps is similar to that in liquids. However, in crystalline molecular solids, the situation is quite different. A few definite cases have been found where a Ps atom does not form or exist. Further work in this area should be very interesting. The foregoing leads us to believe that positronium or positron annihilation can be useful in the study of fundamental properties of molecular liquids and solids.     

Kinetic Models for Granular Flow

The generalization of the Boltzmann and Enskog kinetic equations to allow inelastic collisions provides a basis for studies of granular media at a fundamental level. For elastic collisions the significant technical challenges presented in solving these equations have been circumvented by the use of corresponding model kinetic equations. The objective here is to discuss the formulation of model kinetic equations for the case of inelastic collisions. To illustrate the qualitative changes resulting from inelastic collisions the dynamics of a heavy particle in a gas of much lighter particles is considered first. The Boltzmann–Lorentz equation is reduced to a Fokker–Planck equation and its exact solution is obtained. Qualitative differences from the elastic case arise primarily from the cooling of the surrounding gas. The excitations, or physical spectrum, are no longer determined simply from the Fokker–Planck operator, but rather from a related operator incorporating the cooling effects. Nevertheless, it is shown that a diffusion mode dominates for long times just as in the elastic case. From the spectral analysis of the Fokker–Planck equation an associated kinetic model is obtained. In appropriate dimensionless variables it has the same form as the BGK kinetic model for elastic collisions, known to be an accurate representation of the Fokker–Planck equation. On the basis of these considerations, a kinetic model for the Boltzmann equation is derived. The exact solution for states near the homogeneous cooling state is obtained and the transport properties are discussed, including the relaxation toward hydrodynamics. As a second application of this model, it is shown that the exact solution for uniform shear flow arbitrarily far from equilibrium can be obtained from the corresponding known solution for elastic collisions. Finally, the kinetic model for the dense fluid Enskog equation is described.     

Empirical equations of state for solids

A comparison of three one-parameter empirical equations of state due to Lennard-Jones, Bardeen, and Birch using Bridgman's experimental compression data shows that they do not generally fit the data within experimental error. Heuristic arguments are used to derive a well known three-parameter equation of state which includes these equations as special cases. Several simple two-parameter equations of state, including the Murnaghan equation, can be obtained as special cases of the general form. All of these two-parameter equations are shown to fit Bridgman's data within experimental error with about equal success. It is also shown that the general three-parameter equation, and hence its special cases, is consistent with the observation of Grover, Getting, and Kennedy that the log of the bulk modulus of solids is a linear function of compression. Several of the two-parameter special cases are shown to give satisfactory extrapolations.     

Thermodynamic properties and phase diagram of the graphite-diamond-liquid carbon system

Abstract

We review work performed on a three-phase theoretical carbon equation of state. The algorithm has been used, with good success, in a chemical equilibrium code of mixtures (of solids, liquids, and gasses), in which the gas phase is modeled by a statistical mechanical theory of mixtures. We use simple Grüneisen models for the solid phases and compute the corresponding liquid phases with a “scaling” theory. A modified Lindemann model is used in the scaling theory to predict melting properties. The liquid carbon consists of a mixture of expanded graphitic and diamond-like forms. Terms that describe the electronic energy change of the liquid have been estimated with the INFERNO code. Both experimental and theoretical work has been used to determine the best equation of state parameters. The resulting model yields a phase diagram consistent with all known mutually consistent data. Significant uncertainties still exist in the melting data.     

A conservative discrete compatibility-constraint low-Mach pressure-correction algorithm for time-accurate simulations of variable density flows

In this paper, we develop the discrete compatibility-constraint pressure-correction algorithm for transient simulations of variable density flows at low-Mach numbers. The constraint for the velocity field is constructed from a combination of the discrete equations of continuity and scalar (e.g. energy) transport, imposing that the newly predicted state must be compatible, in agreement with the equation of state. This way, mass and scalar conservation are guaranteed and the equation of state is exactly fulfilled at every time step. For comparison reasons, two other types of well-known pressure-correction algorithms are also used. The first class, denoted as continuity-constraint pressure-correction, is based on a constraint for the velocity field that is derived solely from the continuity equation. The second class, denoted as analytical compatibility-constraint pressure-correction, constructs the constraint from an analytical combination of the material derivative of the equation of state and the continuity and scalar equations. The algorithms are tested for three example fluid configurations: a single-fluid ideal gas, a two-fluid inert mixture and a two-fluid reacting mixture. The latter is special in the sense that the equation of state is non-linear and not everywhere differentiable. The continuity-constraint pressure-correction algorithm yields unstable solutions if density ratios are high. The analytical compatibility-constraint pressure-correction algorithm yields stable results, but the predicted states do not correspond to the equation of state. The discrete compatibility-constraint pressure-correction algorithm performs well on all test cases: the simulation results are stable and exactly match the equation of state.     

Inverted equations of state for solids under high pressures

In the present communication we have reviewed some inverted type equations of state for solids under high pressures. An inverted equation of state (EOS) gives volume as a function of pressure for a solid under isothermal conditions. We have considered various equations of state proposed by earlier workers which express volume as a function of pressure. Expressions for bulk modulus and its pressure derivatives based on such EOSs are obtained and reported here. It is emphasized here that the high pressure derivative properties are very sensitive to the forms of equations of state representing volume-pressure relationships. We have also studied the thermoelastic properties of solids based on pressure derivatives of bulk modulus. Applications have been extended in the present review article to the solids which are metals as well as non-metals including geophysical minerals present in the lower mantle and core of the Earth.     

An electrical test particle in Einstein's unified field theory

Previous work on a class of exact solutions to the field equations of Einstein's unified field theory has shown that some of these solutions acquire an immediate physical meaning as soon as one allows for external sources, as it occurs in the general theory of relativity. It is evident that a four-current density j ⁱ , appended to the right-hand side of the field equation , has a fundamental role: in some solutions, a string built with this current density gives rise to partons, mutually interacting with forces that do not depend on distance, like the ones invoked to explain the confinement of quarks. In other solutions, for which obeys Maxwell's equations, jⁱ clearly displays electrical behavior. In the present paper it is shown under what conditions the electrical behavior of a charged test particle can be extracted from the field equations and from conservation identities related to the theory, when sources are appended in the way proposed by Borchsenius and Moffat.     

Calculation of thermodynamic properties of substances in metastable and labile regions of real gas states

Questions related to the concepts of the equilibrium and stability of a thermodynamic system are considered. Metastable states are defined as fully equilibrium but relatively unstable states. A preferable structure of the equation of state (ES) of a single-component substance has been determined. Equations for the second virial coefficient and ES of a real gas describing the thermodynamic characteristics in a wide range of state parameters within the limits of the error in experimental data have been obtained. This was done with the help of a combined spherically symmetric potential of interaction. With the use of rigorous equations of thermodynamics, it has been found that the isochoric heat capacity in the metastable and labile regions of states remains finite and positive (with the exception of the critical point). It has been shown that, at the transition from the stable region to the region of metastable and labile states, some thermodynamic characteristics such as the isochoric heat capacity, internal energy, enthalpy, and entropy do not have any singularities. Some examples of calculation of these characteristics in the stable, metastable, and labile regions with the help of equations presented by the authors are given. They confirm the validity of the analysis performed in this paper.     

新的适用于整个热力面的1,1,1,2-四氟乙烷(R134a)跨接状态方程

1前言作者建立了一个新型的符合临界重整化群理论的跨接状态方程，能够描述物质的整个区域热力性质山。鉴于R134a是R12的新的主要替代制冷剂，为了计算其整个区域的热力性质，本文将新跨接状态方程应用于R134a，以便提供一个能在整个区域计算R134a热力性质的状态方程。2新跨接状态方程作者建立了以下型式的新跨接状态方程l‘］：上式中，西方一r一IDZ户一p巾c；，一DI—TD；T—To／T；产为密度；pc为临界密度；T为温度；To为临界温度；矿对比过余Helmholtz自由能；A是Helmholtz自由能。新函数中，a。一30，a，一10；0—0．325和西一…     

氦-3状态方程研究进展第二部分:正常液相区和气体区以及全区间状态方程

宽温度和压力范围的3He详细热力性质数据对进行极低温基础科学研究和制冷特性研究是至关重要的.但至今尚缺乏一个热力学统一的解析形式状态方程,来准确描述1K左右到室温300K大温区的3He热力学性质.在收集和整理各类研究3He热力性质文献的基础上,总结了正常液相区和气体区以及全区间3He状态方程的研究状态,这项工作不仅能为关心3He局部区域性质的研究人员提供总结,而且可为今后开发宽范围的3He热力学状态方程提供参考.     

Functional form of the repulsive potential in the high pressure region

The present work is devoted to the analysis of the functional form of the repulsive potential in the framework of soft-sphere model. We used two different approaches which were based on the treatment of an equation of state and spectra of molecular light scattering at large shifts of frequencies. In particular, it has been shown that the density dependence of pressure at P>10³ MPa allowed to calculate the steepness exponent of the repulsive potential as a fitting parameter of the equation of state which possesses reliable extrapolation properties under extrapolating experimental PVT data in the high-pressure region. Processing of experimental data on a base of the statistical equation of state reveals the temperature dependence of the steepness parameter. The similar situation is also typical for the light scattering spectra. So for argon the value of this parameter varies from 15 to 10 in the gas phase and up to 24–28 in the liquid phase. The results obtained with the help of the equation of state and molecular light scattering spectra correlate well.     

Effet Poole-Frenkel dans le monoxyde de silicium dope

The influence of electrical field on the electrical properties of pure or doped silicon monoxyde films has been examined. After analysis and confrontation of the experimental results obtained by direct and alternative currents and by thermally stimulated currents, it has been shown that the same Poole-Frenkel effect appears in these different circumstances. The explanation is based on the heterogeneities in amorphous solids.     

Temperature effects on a new equation of state of solids

Recently we have proposed an isothermal equation of state of solids, and applied it to a variety of substances to show that it agrees with the isothermal pressure-volume data quite accurately up to ultrahigh pressures, and that its agreement with data is superior to the existing equations of state. Further, it has been shown that the bulk modulus and its first pressure derivative, extracted by it, are in excellent agreement with experiment. In the present study, temperature effect is added on this new equation of state, following a widely used approach involving the input of zero-pressure bulk moduli parameters and thermal expansion, all evaluated at a single reference temperature. The resultant temperature-dependent equation of state is applied to predict the isotherms over a wide range of temperature, the thermal expansion as a function of temperature, and the temperature dependence of the isothermal bulk modulus and its pressure derivative. These predictions are tested using literature data for four solids: sodium chloride, gold, molybdenum and tungsten. Good agreement is obtained between theory and data. Furthermore, the predictions are compared with those obtained from a similar temperature-dependent equation of state recently proposed, and the superior prediction capability of our model, in the P-V-T space, is demonstrated.     

A Dynamical Systems Approach to Geodesics in Bianchi Cosmologies

To understand the observational properties of cosmological models, in particular, the temperature of the cosmic microwave background radiation, it is necessary to study their null geodesics. Dynamical systems theory, in conjunction with the orthonormal frame approach, has proved to be an invaluable tool for analyzing spatially homogeneous cosmologies. It is thus natural to use such techniques to study the geodesics of these models. We therefore augment the Einstein field equations with the geodesic equations, all written in dimensionless form, obtaining an extended system of first-order ordinary differential equations that simultaneously describes the evolution of the gravitational field and the behavior of the associated geodesics. It is shown that the extended system is a powerful tool for investigating the effect of space-time anisotropies on the temperature of the cosmic microwave background radiation, and that it can also be used for studying geodesic chaos.     

A Dynamical Systems Approach to Geodesics in Bianchi Cosmologies

To understand the observational properties of cosmological models, in particular, the temperature of the cosmic microwave background radiation, it is necessary to study their null geodesics. Dynamical systems theory, in conjunction with the orthonormal frame approach, has proved to be an invaluable tool for analyzing spatially homogeneous cosmologies. It is thus natural to use such techniques to study the geodesics of these models. We therefore augment the Einstein field equations with the geodesic equations, all written in dimensionless form, obtaining an extended system of first-order ordinary differential equations that simultaneously describes the evolution of the gravitational field and the behavior of the associated geodesics. It is shown that the extended system is a powerful tool for investigating the effect of spacetime anisotropies on the temperature of the cosmic microwave background radiation, and that it can also be used for studying geodesic chaos.