Showing papers on "Binary system published in 1996"

Long-term Stability of Planets in Binary Systems

Abstract: A simple question of celestial mechanics is investigated: in what regions of phase space near a binary system can planets persist for long times? The planets are taken to be test particles moving in the field of an eccentric binary system. A range of values of the binary eccentricity and mass ratio is studied, and both the case of planets orbiting close to one of the stars, and that of planets outside the binary orbiting the systems center of mass, are examined. From the results, empirical expressions are developed for both (1) the largest orbit around each of the stars and (2) the smallest orbit around the binary system as a whole, in which test particles survive the length of the integration (10A4 binary periods). The empirical expressions developed, which are roughly linear in both the mass ratio mu and the binary eccentricity e, are determined for the range 0.0=e=0.7-0.8 and 0.1=mu=0.9 in both regions and can be used to guide searches for planets in binary systems. After considering the case of a single low-mass planet in binary systems, the stability of a mutually interacting system of planets orbiting one star of a binary system is examined, though in less detail.

Thermodynamic calculation of the ternary system Al-Si-C

Abstract: The phase diagram of the ternary system Al-C-Si was optimised using experimental data from the literature. The binary Al-C and Al-Si systems were taken from the literature. The Si-C system was also optimised using the least square method. The calculated sections agree very well with the experimental data.

Evolutionary processes in binary stars

Abstract: 1. Young Binary Stars A.M. Ghez. 2. Observations of Discs Around Pre-Main-Sequence Binary Stars R.D. Mathieu. 3. Dynamical Processes in Binary Star Formation C. Clarke. 4. Young Binary Star/Disk Interactions S.H. Lubow, P. Artymowicz. 5. Chaos and Tidal Capture R.A. Mardling. 6. Hydrodynamic Encounters of Binaries M.B. Davies. 7. Hydrodynamic Instabilities in Close Binary Systems F.A. Rasio. 8. Common Envelope Evolution in Binary Systems M. Livio. 9. Structure and Evolution of Massive Close Binaries D. Vanbeveren. 10. Presupernova Evolution in Massive Binaries Ph. Podsiadlowski, et al. 11. The Formation of Neutron Star and Black Hole Binaries F. Verbunt. 12. Principles of Semi-Detached Binary Evolution H. Ritter. 13. Magnetohydrodynamic Jets and Winds from Accretion Disks H.C. Spruit. 14. Radiation Driven Evolution F. D'Antona. 15. Binary Evolution of Type Ia Supernovae J.C. Wheeler. 16. Black Holes in Binary Stars R.A.M.J. Wijers. 17. Stellar and Dynamical Evolution within Triple Stars P.P. Eggleton, L.G. Kiseleva. 18. Binary Population Synthesis: Theoretical Principles and an Example M. de Kool. 19. An Observational Approach to Binary Population Synthesis H.M. Johnston. Index. Object Index.

Phase equilibria calculations with a modified SAFT equation of state. 2. Binary mixtures of n-alkanes, 1-alkanols, and water

Abstract: The Lennard-Jones−statistical association fluid theory (LJ−SAFT) is applied to binary mixtures containing one self-associating and one nonassociating substance. The binary systems studied here are n-alkane/n-alkane, 1-alkanol/n-alkane, and water/n-alkane mixtures. For cases where the dipole−dipole term is needed, the influence of induction is also investigated. The results with LJ−SAFT exhibit better agreement with experimental data than SAFT. This improvement is due to the exchange of the hard-sphere reference system by the LJ reference system.

Control of iron nitride layers growth kinetics in the binary Fe-N system

Abstract: This study is within the framework of a research program dedicated to defining the optimal conditions for the nitriding of iron and steels at atmospheric pressure by using various mixtures, NH3-N2-H2 and NH3-Ar. After studying the mechanisms of phase formation and mass transfer at the gas-solid interface, a mathematical model is developed in order to predict the nitrogen transfer rate in the solid, the nitride layer growth rate, and the nitrogen concentration profiles. In order to validate the model and to show its possibilities, it is compared with thermogravimetric experiments, analyses, and metallurgical observations (X-ray diffraction, optical microscopy, and electron microprobe anal-ysis). The results obtained allow us to demonstrate the sound correlation between the experimental results and the theoretical predictions. By applying the model to the iron-nitrogen binary system, when the e/γ/α configuration referred to the Fe-N phase diagram is formed, we have experimentally determined the effective diffusion coefficient of nitrogen in the e phase. The latter is constant for a composition of the e nitride between 8 and 9.5 wt pct nitrogen. All the results obtained show that it is possible, by means of dynamic gas flow regulation, to eliminate the incubation period and to control the thickness, composition, and structure of the compound layer at the beginning of the treatment.

An Fd3m Lyotropic Cubic Phase in a Binary Glycolipid/Water System

Abstract: The lyotropic cubic phase of space group Fd3m has been observed for the first time in a purely binary amphiphile/water system, consisting of fully-hydrated synthetic 1,2-di-O-alkyl-3-O-(α- or β-d-x...

Phase equilibria in the aluminium-rich portion of the binary system Co-Al and in the cobalt/aluminium-rich portion of the ternary system Co-Ni-Al

Abstract: Phase equilibria were investigated in the aluminium-rich portion of the binary system Co-Al in the concentration range x co = 0.04 to 0.28. A phase bundle of intermetallic phases Co 4 Al 13 (h), o-Co 4 Al 13 and m-Co 4 Al 13 has been observed between x co = 0.240 and x co = 0.247. The binary high-temperature phase Co 4 Al 13 (h) is formed by a peritectic reaction at 1127°C. It cannot be quenched without lattice distorsion causing significant multiple twinning. By means of slow-cooling Co 4 Al 13 (h) decomposes eutectoidaly at 1083°C into the structural close-related phases: orthorhombic o-Co4Al13 (o-Co 4 Al 13 type) and monoclinic m-Co 4 Al 13 (m-Co 4 Al 13 type). Microstructural as well as X-ray diffraction investigations show that the high-temperature phase Co 4 Al 13 (h) can be stabilized by slight nickel addition. Liquid-quenching of binary Co-Al alloys in the concentration range x co = 0.240 to 0.275 yields the metastable decagonal phase d-CoAl 3 (m). In the cobalt/aluminium-rich portion of the ternary system Co-Ni-Al, phase equilibria for x Ni = 0 to 0.09 and X Al = 0.72 to 0.87 at 1050°C as well as phase equilibria for the partial ternary section Co 25-x Ni x Al 75 (0 ≤ x ≤ 10) have also been investigated. An addition of nickel to the aluminium-rich Co-Al alloys decreases the binary-peritectic temperatures downward to the transition planes.

Synchrotron radiation X-ray diffraction study on phase behavior of PPP-POP binary mixtures

Abstract: The phase behavior of thesn-1,3-dipalmitoyl-2-oleoylglycerol (PPP-POP) binary mixture system was studied by powder X-ray diffraction with synchrotron radiation and by differential scanning calorimetry. The results showed that the immiscible phases were observed in metastable and in the most stable forms. In particular, synchrotron X-ray diffraction enabled us to reveal the monotectic nature of α as a kinetic phase behavior. The equilibrium phase diagram of the PPP-POP mixture is divided into two regions. In POP concentration ratios below 40%, solid-state transformation from α to β was observed, indicating that the α-β transition of PPP was promoted in the presence of POP. By contrast, the polymorphic transition proceeds from α to β through the occurrence of the intermediate β′ form at POP concentration ratios above 50%.

Influence of matrix composition on the solubility of hydroxybenzoic acid isomers in supercritical carbon dioxide

Abstract: Solubilities of p-hydroxybenzoic acid (p-HBA) and mixtures of the para and ortho isomers have been determined in supercritical carbon dioxide at 318 and 328 K for pressures in the range 101−203 bar. The solubility of p-HBA in carbon dioxide (p-HBA/CO2 binary system) is 2 orders of magnitude lower than the binary system solubility of o-HBA. However, measurements undertaken with an equilibrium chamber of mixed para and ortho isomers demonstrate a strong enhancement in the solubility of p-HBA. Furthermore, the enhancement was found to be independent of the composition of the equilibrium chamber. The binary and ternary (p-HBA/o-HBA/CO2) solubility data were correlated using a modified form of the Peng−Robinson equation of state. Covolume-dependent mixing rules were also used with the Peng−Robinson model in an attempt to improve the correlation of solubility data. Conventional supercritical fluid (SCF) extraction of a mixture of the isomers is capable of producing an extract which is 99% pure o-HBA in one extr...

Phase Equilibrium Measurements on Twelve Binary Mixtures

Abstract: Phase equilibrium measurements have been performed on twelve binary mixtures. The PTx method was used to obtain vapor−liquid equilibrium data for the following binary systems at two temperatures each: ethanethiol + propylene; nitrobenzene + methanol; pyridine + ethyl acetate; octane + tert-amyl methyl ether; diisopropyl ether + butane; 1,3-dichloro-2-propanol + epichlorohydrin; 2,3-dichloro-1-propanol + epichlorohydrin; 2,3-epoxy-1-propanol + epichlorohydrin; 3-chloro-1,2-propanediol + epichlorohydrin; methanol + hydrogen cyanide. For these systems, equilibrium vapor and liquid phase compositions were derived from the PTx data using the Soave equation of state to represent the vapor phase and the Wilson, NRTL, or Redlich−Kister activity coefficient model to represent the liquid phase. The infinite dilution activity coefficient of methylamine in N-methyl-2-pyrrolidone was determined at three temperatures by performing PTx measurements on the N-methyl-2-pyrrolidone-rich half of the binary. Liquid−liquid eq...

Density, Refractive Index, Viscosity, and Speed of Sound in Binary Mixtures of 2-Ethoxyethanol with Dioxane, Acetonitrile, and Tetrahydrofuran at (298.15, 303.15, and 308.15) K

Abstract: Density, refractive index, viscosity, and speed of sound data in binary mixtures of 2-ethoxyethanol with dioxane, acetonitrile, and tetrahydrofuran are presented at (298.15, 303.15, and 308.15) K over the whole range of mole fractions at atmospheric pressure. These results are used to calculate excess molar volume, deviations in molar refractivity, viscosity, and isentropic compressibility. The calculated quantities are further fitted to the Redlich−Kister equation to estimate the binary interaction parameters and mean deviations from the regression lines. The sign and magnitude of the computed parameters are discussed to study the nature and type of intermolecular interactions in binary mixtures.

Gibbs energies of formation of chromium carbides

Abstract: The carbon potentials corresponding to the two-phase mixtures Cr + Cr23C6, Cr23C6 + Cr7C3, and Cr7C3 + Cr3C2 in the binary system Cr-C were measured in the temperature range 973 to 1173 K by using the methane-hydrogen gas equilibration technique. Special precautions were taken to prevent oxidation of the samples and to minimize thermal segregation in the gas phase. The standard Gibbs energies of formation of Cr23C6, Cr7C3, and Cr3C2 were derived from the measured carbon potentials. These values are compared with those reported in the literature. The Gibbs energies obtained in this study agree well with those obtained from solid-state cells incorporating CaF2 and ThO2(Y2O3) as solid electrolytes and sealed capsule isopiestic measurements reported in the literature.

Densities, viscosities, and refractive indices of some binary liquid systems of methanol + isomers of hexanol at 298.15 K

Abstract: Viscosities, densities, and refractive indices of eight binary liquid systems containing ethanol + some isomers of hexanol have been determined at 298.15 K. The excess property values were fitted to the Redlich-Kister equation to estimate the binary coefficients and the standard deviations.

Crystalline and amorphous phases in the binary system water-raffinose

Abstract: The melting points, glass transitions and enthalpies of fusion of crystalline hydrates in binary water–raffinose mixtures have been studied by differential scanning calorimetery (DSC) over the accessible composition range. X-Ray diffraction was used to identify the crystalline forms. From the liquidus and solidus curves and shapes of the DSC scans, a raffinose trihydrate has been identified, and lower hydrates are also believed to exist. The melting points and enthalpies of fusion of raffinose pentahydrate and trihydrate are 352.7±0.1 K, 88.0±0.4 kJ mol -1 and 358.4 K, 47.6 kJ mol -1 , respectively. In the phase coexistence curve at higher raffinose concentrations a minimum point is observed, which is thought to be the eutectic of trihydrate and a lower hydrate. The raffinose mole fraction of the eutectic is 0.347, and its melting point and enthalpy of fusion are 356.6 K and 51.4 J g -1 . The raffinose mole fraction of the ice–pentahydrate eutectic is 7.9×10 -3 , and its melting point and enthalpy of fusion are 270.4±0.2 K and 237.6±0.5 J g -1 , respectively. The glass-transition profile for the binary system has been measured over the experimentally accessible composition range and the data fitted to the Gordon–Taylor equation, from which the glass-transition temperature for anhydrous raffinose is obtained as 376.4 K. Rehydration and recrystallisation rates of anhydrous, amorphous raffinose taking place during storage over media of constant relative humidity have been studied by measurements of shifts in the glass-transition and melting temperatures. The kinetics of water uptake, and of the subsequent crystallisation of raffinose pentahydrate from the amorphous substrates, show a complex dependence on relative humidity and temperature, which requires further study.

Isobaric Vapor−Liquid Equilibria for Binary Systems Composed of Octane, Decane, and Dodecane at 20 kPa

Abstract: Vapor−liquid equilibria were measured for binary systems of octane + decane, decane + dodecane, and octane + dodecane at 20.00 kPa using a recirculating still. The results are thermodynamically consistent according to the point-to-point consistency test, and deviation from ideal behavior is small for all systems.

Thermodynamic Evaluation of the Bi-Cu-O System

Abstract: A thermodynamic evaluation of the ternary Bi-Cu-O system has been made and a set of parameters consistently describing the system at 1 bar total pressure has been determined. The ternary system contains a liquid phase which is continuous at high temperature and separates into a metal liquid and an oxide liquid at low temperature and the ternary compound Bi2CuO4 in addition to the binary compounds. Concentration/temperature diagrams are given for the Bi2O3-CuOx system at oxygen partial pressures of 1, 0.21 and 10−5 bar, as well as a potential diagram. Selected isothermal sections at 1100 and 1473 K are also presented. Available experimental data are rather limited and often show a relatively large scatter, but nevertheless make it possible to determine a sufficient set of thermodynamic parameters.

Thermodynamics of the Phase Formation of the Titanium Silicides

Abstract: Vaporization thermodynamics in the titanium−silicon binary system has been studied by a Knudsen effusion−mass spectrometer technique. The equilibrium vapor pressure of silicon gas over two-phase mi...

Density functional theory: Structure and interfacial properties of binary mixtures

Abstract: Based on Density Functional Theory (DFT) of inhomogeneous fluid mixtures we model the liquid-vapour interface of some binary mixtures. Attractive contributions to the Helmholtz free energy are treated by a mean-field approximation (MF). The local density approximation (LDA) is applied to the repulsive reference system described by a hard sphere equation of state. A cut-off and shifted Lennard-Jones-12-6 potential divided according to the WCA-prescription is used as interaction pair potential. Binary Lennard-Jones parameter are introduced and fitted to experimental liquid-vapour compositions to describe interactions between different species. The calculations give good results in the case of simple fluid mixtures like Ar-N 2 and CO-N 2 . Similar results are obtained for the nonpolar mixture n-heptane-toluene. The predicted surface tensions γ agree very well with experimental data. Computed partial density profiles clearly show the enrichment of the component with the lower surface tension in the interphase. The relative Gibbs surface excess concentration is calculated from partial density profiles and compared with experimental values. The influence of activity coefficients on Gibbs adsorption is discussed.