Modelling of Phase Diagram Boundaries at Equilibrium of Two Binary Regular Phases

1995 ◽  
Vol 60 (6) ◽  
pp. 911-916
Author(s):  
Jan Vřešťál ◽  
Ivo Stloukal
Keyword(s):  
Phase Diagram ◽  
Linear Function ◽  
Regular Solution ◽  
Gibbs Function ◽  
Temperature Dependent ◽  
Regular Solutions ◽  
Liquid Phases ◽  
Simplifying Assumptions ◽  
Two Phases ◽  
Solution Parameter

The conditions of occurrence of extremes on the solidus and liquidus curves in a binary isobaric phase diagram are specified. The solid and liquid phases are regarded as regular solutions in equilibrium. Two simplifying assumptions are made: (i) the Gibbs function of melting of the pure components is a linear function of temperature; (ii) the two phases in equilibrium are regular solutions with a temperature-dependent regular solution parameter. The conditions of occurrence of inflexion points on the solidus and/or liquidus curves are obtained by modelling.

ROUGHNESS INFLUENCE ON SURFACE MELTING

2001 ◽  
Vol 08 (06) ◽  
pp. 599-608 ◽  
Author(s):  
FRAY DE LANDA CASTILLO ALVARADO ◽  
MARGARITO CRUZ PINEDA ◽  
JERZY H. RUTKOWSKI ◽  
LESZEK WOJTCZAK
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Phase Diagram ◽  
Order Parameter ◽  
Surface Melting ◽  
Density Fluctuations ◽  
Solid Model ◽  
Van Der Waals Equation ◽  
Liquid Phases ◽  
Two Phases

The influence of surface roughness on surface melting phase transition is discussed within the molecular field theory. The roughness is characterized by the surface order parameter averaged over all the density fluctuations whose description corresponds to the discrete Gaussian solid-on-solid model. The potential governing the transition between the rough surface and the surface melting is considered in terms of the modified van der Waals equation of state. Its effective shape represents two intersecting parabolas with nonequal curvatures for the solid and liquid phases. The phase diagram shows the coexistence of two phases with rough and wet surfaces.

A discussion on equations of phase equilibrium between two regular binary phases

1981 ◽  
Vol 46 (6) ◽  
pp. 1433-1438
Author(s):  
Jan Vřešťál
Keyword(s):  
Phase Equilibrium ◽  
Linear Function ◽  
Concentration Dependence ◽  
Absolute Temperature ◽  
Enthalpy Change ◽  
Independent Parameter ◽  
Free Enthalpy ◽  
Regular Solutions ◽  
Regular Model ◽  
Concentration Dependences

The conditions of the existence of extreme on the concentration dependences of absolute temperature (x are mole fractions) T = Tα(xkα) and T = Tβ(xkβ) denoting equilibrium between two binary regular solutions are generally developed under two assumptions: 1) Free enthalpy change of pure components k = i, j at transition from phase α to β is a linear function of temperature. 2) Concentration dependence of excess free enthalpy (identical with enthalpy) of solutions α and β, respectively, is described in regular model by one concentration and temperature independent parameter for each individual phase.

Review Lectures on Senescence: I. The Causes of Aging

2001 ◽  
Vol 2001 (1) ◽  
Author(s):  
J. Maynard Smith
Keyword(s):  
Aging Process ◽  
Somatic Mutations ◽  
Cellular Level ◽  
Temperature Dependent ◽  
Theories Of Aging ◽  
Organ Systems ◽  
Two Phases ◽  
Effects Of Radiation ◽  
The Individual ◽  
Do So

Aging processes are defined as those that increase the susceptibility of individuals as they grow older to the factors that may cause death. Various possible theories of aging are considered, and evidence that may help to decide between them is discussed. Changes in different organ systems may be merely symptoms of some single aging process, or they may be largely independent and synchronized by natural selection. Even if different organ systems age independently, they may do so as a result of similar changes at a cellular level. Cellular theories of aging may have to take into account the effects of selection between the cells in a tissue. The effects of radiation and somatic mutation theories of aging are discussed. It is suggested that radiation shortens life by inducing somatic mutations but that normal aging is not to any important extent caused by somatic mutations, although it may result from changes in cells that have effects on the physiology of the individual similar to those of somatic mutations. Evidence is presented that in Drosophila and in mice there are two phases in the life-span. In Drosophila , there is an initial “aging” phase, which is irreversible and occurs at a rate approximately independent of temperature, and a second “dying” phase, which is temperature-dependent in rate and reversible at lower temperatures. Reproduced by permission. J. Maynard Smith, Review Lectures on Senescence: I. The Causes of Aging. Proc. R. Soc. London Ser. B 157 , 115-127 (1962).

C100 IPR fullerenes: temperature-dependent relative stabilities based on the Gibbs function

2004 ◽  
Vol 306 (1-3) ◽  
pp. 93-104 ◽  
Author(s):  
Xiang Zhao ◽  
Hitoshi Goto ◽  
Zdenek Slanina
Keyword(s):  
Gibbs Function ◽  
Temperature Dependent ◽  
Relative Stabilities

scholarly journals Estimation of flow velocity for a debris flow via the two-phase fluid model

2015 ◽  
Vol 22 (1) ◽  
pp. 109-116 ◽  
Author(s):  
S. Guo ◽  
P. Xu ◽  
Z. Zheng ◽  
Y. Gao
Keyword(s):  
Debris Flow ◽  
Real World ◽  
Empirical Formula ◽  
Debris Flows ◽  
Fluid Model ◽  
Two Phase ◽  
Liquid Phases ◽  
Two Phases ◽  
Phase Fluid ◽  
Steady Velocity

Abstract. The two-phase fluid model is applied in this study to calculate the steady velocity of a debris flow along a channel bed. By using the momentum equations of the solid and liquid phases in the debris flow together with an empirical formula to describe the interaction between two phases, the steady velocities of the solid and liquid phases are obtained theoretically. The comparison of those velocities obtained by the proposed method with the observed velocities of two real-world debris flows shows that the proposed method can estimate the velocity for a debris flow.

Theoretical Studies of Copper Oxide Clusters: Prediction of an Electronically Driven Phase Separation in YBa2Cu3Ox

1987 ◽  
Vol 99 ◽  
Author(s):  
L. A. Curtiss ◽  
T. O. Brun ◽  
D. M. Gruen
Keyword(s):  
Phase Diagram ◽  
Phase Separation ◽  
High Temperature ◽  
Copper Oxide ◽  
Superconducting Phase ◽  
Oxygen Stoichiometry ◽  
Molecular Orbital Calculations ◽  
Theoretical Studies ◽  
Two Phases ◽  
Semi Empirical

ABSTRACTOn the basis of semi-empirical extended Hiickel molecular orbital calculations of copper-oxide clusters representing the new superconducting material YBa2Cu3Ox, a phase diagram is proposed which suggests that the 94 K high temperature superconducting phase of YBa2Cu3Ox is characterized by an oxygen stoichiometry near 7.0. The phase diagram predicts that a plateau should exist for Tc in the region x = 0.0 – 0.25 and that in this region two phases are present which are characterized by compositions having oxygen stoichiometries 6.5–6.75 and ca. 7.0.

scholarly journals Tiny Bubbles

2009 ◽  
Vol 17 (1) ◽  
pp. 3-5
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Lower Energy ◽  
Critical Role ◽  
Interfacial Area ◽  
Consumer Products ◽  
Phase System ◽  
Two Phase ◽  
Liquid Phases ◽  
Phase Systems ◽  
Two Phases

This is not an article about the song made famous by the late (great) Don Ho. This is about a breakthrough in the understanding of how micrometer-sized bubbles can be stabilized for long periods of time. This can influence the taste, smell, and consistency of consumer products including food and cosmetics.In two-phase systems, which can include air (as bubbles) suspended within a liquid, the structures of the dispersed (bubbles) and continuous (liquid) phases play a critical role in determining the properties of the material. There is also the function of time in that the microstructure of the dispersed phase continuously evolves toward a state of lower energy by minimizing the surface area between the two phases (referred to as the interfacial area). In the long term, this time evolution diminishes the usefulness of two-phase systems. Emilie Dressaire, Rodney Bee, David Bell, Alex Lips, and Howard Stone have devised a way to stabilize a two-phase system for time periods of a year or longer.

Forced Convection Condensation on a Horizontal Tube: Influence of Turbulence in the Vapor and Liquid Phases

1999 ◽  
Vol 121 (4) ◽  
pp. 874-885 ◽  
Author(s):  
D. Homescu ◽  
P. K. Panday
Keyword(s):  
Turbulence Models ◽  
Horizontal Tube ◽  
Transfer Coefficients ◽  
Flow Equations ◽  
Heat Transfer Coefficients ◽  
Liquid Phases ◽  
Implicit Finite Difference Scheme ◽  
Implicit Finite Difference ◽  
Two Phases ◽  
Good Agreement

An implicit finite difference scheme is used to solve the problem of condensation of pure vapors flowing vertically downwards around a horizontal tube. The incompressible flow equations coupled at the interface for the liquid and vapor phases are solved. The pressure gradient, inertia, and enthalpy convection terms are retained in this analysis, and the influence of turbulence in the two phases is considered. The calculated results for laminar flow and those from different mixing length turbulence models are compared with experimental results for condensation of steam and R113. The results presented show that the average condensation heat transfer coefficients obtained using Kato’s turbulence model in the condensate film and Pletcher’s model in the vapor phase, are in good agreement with the experimental data.

Sign in / Sign up

Export Citation Format

Share Document