WorldWideScience

Sample records for binary alloy systems

  1. Estimating the Eutectic Composition of Simple Binary Alloy System Using Linear Geometry

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    Muhammed Olawale Hakeem AMUDA

    2008-06-01

    Full Text Available A simple linear equation was developed and applied to a hypothetical binary equilibrium diagram to evaluate the eutectic composition of the binary alloy system. Solution of the equations revealed that the eutectic composition of the case study Pb – Sn, Bi – Cd and Al – Si alloys are 39.89% Pb, 60.11% Sn, 58.01% Bi, 41.99% Cd and 90.94% Al, 9.06% Si respectively. These values are very close to experimental values. The percent deviation of analytical values from experimental values ranged between 2.87 and 5% for the three binary systems considered, except for Si – Al alloy in which the percent deviation for the silicon element was 22%.It is concluded that equation of straight line could be used to predict the eutectic composition of simple binary alloys within tolerable experimental deviation range of 2.5%.

  2. Solid state amorphisation in binary systems prepared by mechanical alloying

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    Gonzalez, G., E-mail: gemagonz@ivic.v [Lab. Ciencia e Ing. de Materiales, Instituto Venezolano de Investigaciones Cientificas, IVIC, Caracas (Venezuela, Bolivarian Republic of); Sagarzazu, A. [Lab. Ciencia e Ing. de Materiales, Instituto Venezolano de Investigaciones Cientificas, IVIC, Caracas (Venezuela, Bolivarian Republic of); Bonyuet, D. [Instituto de Investigacion en Biomedicina y Ciencias Aplicadas, Universidad de Oriente, Cumana (Venezuela, Bolivarian Republic of); D' Angelo, L. [UNEXPO, Universidad Experimental Politecnica Luis Caballero Mejias, Dpto. Ing. Mecanica (Venezuela, Bolivarian Republic of); Villalba, R. [Lab. Ciencia e Ing. de Materiales, Instituto Venezolano de Investigaciones Cientificas, IVIC, Caracas (Venezuela, Bolivarian Republic of)

    2009-08-26

    In the present work a detailed study of amorphisation in different systems prepared by mechanical alloying under the same experimental conditions was carried out, milling up to 50 and 100 h in some cases. The systems studied were: AlTi, AlNi, AlFe, FeNi, FeCo, NiMo, NiW, NiCo, MoW, CoMo. These systems were chosen to study the effect of Al-transition metal, transition metal-transition metal and also systems with large and small negative heat of mixing, different and similar crystal structures, atomic sizes and diffusion coefficients. Calculations based on the Miedema model for alloy formation and amorphisation on all the alloys studied were performed. The experimental results from X-ray diffraction and transmission electron microscopy showed that the systems based on Fe (FeNi, FeCo and FeAl) did not amorphised, even after milling for 100 h, and formed a stable solid solution with a nanometric grain size of 7 nm. The systems NiMo, NiW, MoW and CoMo (systems with small negative heat of mixing), showed amorphisation after 50 h of milling. NiAl and TiAl form an intermediate amorphous phase after around 20 h of milling and with further milling they recrystallize into a fcc solid solution. Agreement between the theoretical calculations based on the Miedema model and the experimental results was found in most of the systems.

  3. Thermodynamic analysis of the change of solid solubility in a binary system processed by mechanical alloying

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    Aguilar, C. [Instituto de Materiales y Procesos Termomecanicos, Facultad de Ciencias de la Ingenieria, Universidad Austral de Chile, Av. General Lagos 2086, Valdivia (Chile)], E-mail: ceaguilar@uach.cl; Martinez, V. [TEKMETALL, Metallurgical Solutions S.L., Po de Manuel Lardizabal No17, 20018 Donostia-Gipuzkoa (Spain); Navea, L.; Pavez, O.; Santander, M. [Departamento de Metalurgia, Facultad de Ingenieria, Universidad de Atacama, Av. Copayapu 485, Copiapo (Chile)

    2009-03-05

    Using a non-equilibrium process, it is possible to extend the solid solubility range in metallic systems. Therefore, the main objective of this work was to apply a thermodynamic model to predict the change in the solubility limit of systems with positive enthalpy mixing (Cu-Cr and Fe-Cu) processed by mechanical alloying. It was found that increasing the density of crystalline defects alters the solubility limit in these binary systems.

  4. Simulation of nuclei morphologies for binary alloy

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We study the critical nuclei morphologies of a binary alloy by the string method. The dynamic equation of the string, connecting the metastable phase (liquid) and stable phase (solid), is governed by Helmholtz free energy for the binary alloy system at a given temperature. The stationary string through the critical nucleus (saddle point) is obtained if the relaxation time of the string is su?ciently large. The critical nucleus radius and energy barrier to nucleation of a pure alloy with isotropic interface energy in two and three dimensions are calculated, which are consistent with the classical nucleation theory. The critical nuclei morphologies are sensitive to the anisotropy strength of interface energy and interface thickness of alloy in two and three dimensions. The critical nucleus and energy barrier to nucleation become smaller if the anisotropy strength of the interface energy is increased, which means that it is much easier to form a stable nucleus if the anisotropy of the interface energy is considered.

  5. NUMERICAL ANALYSES FOR TREATING DIFFUSION IN SINGLE-, TWO-, AND THREE-PHASE BINARY ALLOY SYSTEMS

    Science.gov (United States)

    Tenney, D. R.

    1994-01-01

    This package consists of a series of three computer programs for treating one-dimensional transient diffusion problems in single and multiple phase binary alloy systems. An accurate understanding of the diffusion process is important in the development and production of binary alloys. Previous solutions of the diffusion equations were highly restricted in their scope and application. The finite-difference solutions developed for this package are applicable for planar, cylindrical, and spherical geometries with any diffusion-zone size and any continuous variation of the diffusion coefficient with concentration. Special techniques were included to account for differences in modal volumes, initiation and growth of an intermediate phase, disappearance of a phase, and the presence of an initial composition profile in the specimen. In each analysis, an effort was made to achieve good accuracy while minimizing computation time. The solutions to the diffusion equations for single-, two-, and threephase binary alloy systems are numerically calculated by the three programs NAD1, NAD2, and NAD3. NAD1 treats the diffusion between pure metals which belong to a single-phase system. Diffusion in this system is described by a one-dimensional Fick's second law and will result in a continuous composition variation. For computational purposes, Fick's second law is expressed as an explicit second-order finite difference equation. Finite difference calculations are made by choosing the grid spacing small enough to give convergent solutions of acceptable accuracy. NAD2 treats diffusion between pure metals which form a two-phase system. Diffusion in the twophase system is described by two partial differential equations (a Fick's second law for each phase) and an interface-flux-balance equation which describes the location of the interface. Actual interface motion is obtained by a mass conservation procedure. To account for changes in the thicknesses of the two phases as diffusion

  6. Plutonium microstructures. Part 2. Binary and ternary alloys

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    Cramer, E.M.; Bergin, J.B.

    1983-12-01

    This report is the second of three parts that exhibit illustrations of inclusions in plutonium metal from inherent and tramp impurities, of intermetallic and nonmetallic constituents from alloy additions, and of the effects of thermal and mechanical treatments. This part includes illustrations of the microstructures in binary cast alloys and a few selected ternary alloys that result from measured additions of diluent elements, and of the microconstituents that are characteristic of phase fields in extended alloy systems. Microhardness data are given and the etchant used in the preparation of each sample is described.

  7. Boundaries of the homologous phases in Sb–Te and Bi–Te binary alloy systems

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    Kifune, K., E-mail: k.kifune.yw@cc.it-hiroshima.ac.jp [Hiroshima Institute of Technology, Research Center for Condensed Matter Physics, 2-1-1 Miyake, Saeki-ku, Hiroshima 731-5193 (Japan); Tachizawa, T.; Kanaya, H.; Kubota, Y. [Osaka Prefecture University, Graduate School of Science, Osaka 599-8531 (Japan); Yamada, N. [Kyoto University, Department of Materials Science & Engineering, Kyoto 606-8501 (Japan); Matsunaga, T. [Panasonic Corporation, Advanced Research Division, Osaka 571-8501 (Japan)

    2015-10-05

    Highlights: • Phase boundary of the homologous phase in Sb–Te is fixed at Sb{sub 20}Te{sub 3} compound. • Crystal structure of Sb{sub 20}Te{sub 3} is refined by the 4D structure analysis. • Phase boundary of the homologous phase in Bi–Te is fixed at Bi{sub 8}Te{sub 3} compound. • Crystal structure of Bi{sub 8}Te{sub 3} is refined by the 4D structure analysis. • Difference between Sb–Te and Bi–Te systems are proposed. - Abstract: Sb–Te and Bi–Te binary systems have long-period stacking structures called homologous phases. Within these structures, two types of fundamental structural units change their numbers according to their composition, and the stacking periods also change systematically. X-ray powder diffraction data on bulk specimens with different compositions reveal both the phase boundaries of the homologous phases and the structures of the boundary phases. The boundary phases are Sb{sub 20}Te{sub 3} in the Sb–Te system and Bi{sub 8}Te{sub 3} in the Bi–Te system.

  8. Structure Map for Embedded Binary Alloy Nanocrystals

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    Yuan, C.W.; Shin, S.J.; Liao, C.Y.; Guzman, J.; Stone, P.R.; Watanabe, M.; Ager III, J.W.; Haller, E.E.; Chrzan, D.C.

    2008-09-20

    The equilibrium structure of embedded nanocrystals formed from strongly segregating binary-alloys is considered within a simple thermodynamic model. The model identifies two dimensionlessinterface energies that dictate the structure, and allows prediction of the stable structure for anychoice of these parameters. The resulting structure map includes three distinct nanocrystal mor-phologies: core/shell, lobe/lobe, and completely separated spheres.

  9. Relations between the modulus of elasticity of binary alloys and their structure

    Science.gov (United States)

    Koster, Werner; Rauscher, Walter

    1951-01-01

    A comprehensive survey of the elastic modulus of binary alloys as a function of the concentration is presented. Alloys that form continuous solid solutions, limited solid solutions, eutectic alloys, and alloys with intermetallic phases are investigated. Systems having the most important structures have been examined to obtain criteria for the relation between lattice structure, type of binding, and elastic behavior.

  10. Modeling selective intergranular oxidation of binary alloys

    Science.gov (United States)

    Xu, Zhijie; Li, Dongsheng; Schreiber, Daniel K.; Rosso, Kevin M.; Bruemmer, Stephen M.

    2015-01-01

    Intergranular attack of alloys under hydrothermal conditions is a complex problem that depends on metal and oxygen transport kinetics via solid-state and channel-like pathways to an advancing oxidation front. Experiments reveal very different rates of intergranular attack and minor element depletion distances ahead of the oxidation front for nickel-based binary alloys depending on the minor element. For example, a significant Cr depletion up to 9 μm ahead of grain boundary crack tips was documented for Ni-5Cr binary alloy, in contrast to relatively moderate Al depletion for Ni-5Al (˜100 s of nm). We present a mathematical kinetics model that adapts Wagner's model for thick film growth to intergranular attack of binary alloys. The transport coefficients of elements O, Ni, Cr, and Al in bulk alloys and along grain boundaries were estimated from the literature. For planar surface oxidation, a critical concentration of the minor element can be determined from the model where the oxide of minor element becomes dominant over the major element. This generic model for simple grain boundary oxidation can predict oxidation penetration velocities and minor element depletion distances ahead of the advancing front that are comparable to experimental data. The significant distance of depletion of Cr in Ni-5Cr in contrast to the localized Al depletion in Ni-5Al can be explained by the model due to the combination of the relatively faster diffusion of Cr along the grain boundary and slower diffusion in bulk grains, relative to Al.

  11. Electrical conductivity and phase diagram of binary alloys. 21: The system palladium-chromium

    Science.gov (United States)

    Grube, G.; Knabe, R.

    1985-01-01

    Pd-Cr alloys were investigated by thermal analysis, hardness measurements, X-ray analysis, microscopic examination of etched pieces, and temperature-resistance curves of the solid alloys. Only one compound, Pd2Cr3, m, 1389 deg, is formed. It possesses a cubic face centered lattice and forms with excess Pd a series of solid solutions with a minimum m.p. at 45 atoms% Pd. Hardness maximum appears at the Pd2Cr3 point. Pd2Cr3 forms no solid solutions with Cr but eutectic point appears at 25 atoms% Pd, m. 1320 deg. The sp. resistance of pure Cr in an atom of H, indicates no allotropic forms. Cr2O3 is solid in molten Cr. Pure Cr melts at 1890 plus or minus 10 deg but Cr contg. Cr2O3 starts to melt at 1770 to 1790 deg.

  12. Model for magnetic-nonmagnetic binary alloys

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    Razafimandimby, H. [Departement de Physique, Universite de Toliara, 601 Toliara (Madagascar); Randrianasoloharisoa, D. [LPMR, Universite d' Antananarivo (Madagascar); Rakotomahevitra, A. [Departement des Sciences Exactes, Universite de Mahajanga, BP 155 (Madagascar); Parlebas, J.C. [IPCMS, UMR 7504 CNRS-Universite Louis Pasteur, 23 rue du Loess, BP 43, 67034 Strasbourg (France)

    2007-10-15

    An extension of a mean-field approximation (MFA) developed within standard basis operators (SBO) is used to study magnetism in magnetic-nonmagnetic binary alloys. The Curie temperature is calculated from the free energy within the framework of the present approach. The calculated results are in fair agreement with the theoretical results of other research groups for the same problem but utilizing other methods. Finally, the case of NiPt alloys is briefly examined as an example test for the comparison with experiment. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Ordering in binary transition metal alloys

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    Rusakov, G. [Institute for Metal Physics UB RAS, 18 Kovalevskoj St., 620990 Ekaterinburg (Russian Federation); Ural State Technical University - UPI, 19 Mira St., 620002 Ekaterinburg (Russian Federation); Son, L., E-mail: ldson@yandex.ru [Ural State Pedagogical University, 26 Cosmonavtov Ave, 620017 Ekaterinburg (Russian Federation); Efimova, E. [Institute for Metal Physics UB RAS, 18 Kovalevskoj St., 620990 Ekaterinburg (Russian Federation); Ural State Technical University - UPI, 19 Mira St., 620002 Ekaterinburg (Russian Federation); Dubinin, N. [Institute for Metallurgy UB RAS, 101 Amundsen St., 620016 Ekaterinburg (Russian Federation); Ural State Technical University - UPI, 19 Mira St., 620002 Ekaterinburg (Russian Federation)

    2012-03-20

    We present the phenomenological thermodynamic modeling of binary alloys which demonstrate solubility of the components at high temperatures, and form intermediate phase near equiatomic composition at lower ones (the so-called sigma-phase). Besides, the regular solution miscibility gap takes place also. The nonequilibrium thermodynamic potential is written out as a sum of the free energy of regular solution and polynomial term of scalar order parameter {phi}, which describes the {sigma}-phase ordering. There are four parameters in the model: the energy of regular solution mixing, the energy of {sigma}-phase formation at zero temperature, and the widths of temperature and concentration intervals of {sigma}-phase existence in the alloy with frozen-in random distribution of components. Up to now, both phase transitions which take place in a number of transition metals binary alloys (the {sigma}-phase formation and miscibility in the regular solution) have been treated separately. In present work, the standard technique of phase diagram calculation allows us to analyze all possible phase diagrams which may arise in the alloy.

  14. Copper-based alloys, crystallographic and crystallochemical parameters of alloys in binary systems Cu-Me (Me=Co, Rh, Ir, Cu, Ag, Au, Ni, Pd, Pt)

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    Porobova, Svetlana, E-mail: porobova.sveta@yandex.ru; Loskutov, Oleg, E-mail: lom58@mail.ru [Tomsk State University of Architecture and Building, Russia, Tomsk, 2 Solyanaya sq, Tomsk, 634003 (Russian Federation); Markova, Tat’jana, E-mail: patriot-rf@mail.ru [Siberian State Industrial University. 42 Kirov St., Novokuznetsk, 654007 (Russian Federation); Klopotov, Vladimir, E-mail: vdklopotov@mail.ru [Research Tomsk Polytechnic University, 30 Lenin Ave., Tomsk, 634050 (Russian Federation); Klopotov, Anatoliy, E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, Russia, Tomsk, 2 Solyanaya sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36, Lenin Ave., Tomsk, 634050 (Russian Federation); Vlasov, Viktor, E-mail: vik@tsuab.ru [Tomsk State University of Architecture and Building, Russia, Tomsk, 2 Solyanaya sq, Tomsk, 634003 (Russian Federation); Research Tomsk Polytechnic University, 30 Lenin Ave., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The article presents the results of the analysis of phase equilibrium of ordered phases in binary systems based on copper Cu- Me (where Me - Co, Rh, Ir, Ag, Au, Ni, Pd, Pt) to find correlations of crystallochemical and crystallographic factors. It is established that the packing index in disordered solid solutions in binary systems based on copper is close to the value of 0.74 against the background of an insignificant deviation of atomic volumes from the Zen’s law.

  15. Copper-based alloys, crystallographic and crystallochemical parameters of alloys in binary systems Cu-Me (Me=Co, Rh, Ir, Cu, Ag, Au, Ni, Pd, Pt)

    Science.gov (United States)

    Porobova, Svetlana; Markova, Tat'jana; Klopotov, Vladimir; Klopotov, Anatoliy; Loskutov, Oleg; Vlasov, Viktor

    2016-01-01

    The article presents the results of the analysis of phase equilibrium of ordered phases in binary systems based on copper Cu- Me (where Me - Co, Rh, Ir, Ag, Au, Ni, Pd, Pt) to find correlations of crystallochemical and crystallographic factors. It is established that the packing index in disordered solid solutions in binary systems based on copper is close to the value of 0.74 against the background of an insignificant deviation of atomic volumes from the Zen's law.

  16. Binary Colloidal Alloy Test-5: Phase Separation

    Science.gov (United States)

    Lynch, Matthew; Weitz, David A.; Lu, Peter J.

    2008-01-01

    The Binary Colloidal Alloy Test - 5: Phase Separation (BCAT-5-PhaseSep) experiment will photograph initially randomized colloidal samples onboard the ISS to determine their resulting structure over time. This allows the scientists to capture the kinetics (evolution) of their samples, as well as the final equilibrium state of each sample. BCAT-5-PhaseSep studies collapse (phase separation rates that impact product shelf-life); in microgravity the physics of collapse is not masked by being reduced to a simple top and bottom phase as it is on Earth.

  17. Point Defects in Binary Laves-Phase Alloys

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    Liaw, P.K.; Liu, C.T.; Pike, L.M.; Zhu, J.H.

    1999-01-11

    Point defects in the binary C15 NbCrQ and NbCoz, and C 14 NbFe2 systems on both sides of stoichiometry were studied by both bulk density and X-ray Iattiee parameter measurements. It was found that the vacancy concentrations in these systems after quenching from 1000"C are essentially zero. The constitutional defects on both sides of stoichiometry for these systems were found to be of the anti-site type in comparison with the model predictions. Thermal vacancies exhibiting a maximum at the stoichiometric composition were obtained in NbCr2 Laves phase alloys after quenching from 1400"C. However, there are essentially no thermal vacancies in NbFe2 alloys after quenching from 1300oC. Anti-site hardening was found on both sides of stoichiometry for all the tie Laves phase systems studied, while the thermal vacancies in NbCr2 alloys quenched from 1400'C were found to soften the Laves phase. The anti-site hardening of the Laves phases is similar to that of the B2 compounds and the thermal vacancy softening is unique to the Laves phase. Neither the anti-site defects nor the thermal vacancies affect the fracture toughness of the Laves phases significantly.

  18. Point Defects in Binary Laves-Phase Alloys

    International Nuclear Information System (INIS)

    Point defects in the binary C15 NbCrQ and NbCoz, and C 14 NbFe2 systems on both sides of stoichiometry were studied by both bulk density and X-ray Iattiee parameter measurements. It was found that the vacancy concentrations in these systems after quenching from 1000''C are essentially zero. The constitutional defects on both sides of stoichiometry for these systems were found to be of the anti-site type in comparison with the model predictions. Thermal vacancies exhibiting a maximum at the stoichiometric composition were obtained in NbCr2 Laves phase alloys after quenching from 1400''C. However, there are essentially no thermal vacancies in NbFe2 alloys after quenching from 1300oC. Anti-site hardening was found on both sides of stoichiometry for all the tie Laves phase systems studied, while the thermal vacancies in NbCr2 alloys quenched from 1400'C were found to soften the Laves phase. The anti-site hardening of the Laves phases is similar to that of the B2 compounds and the thermal vacancy softening is unique to the Laves phase. Neither the anti-site defects nor the thermal vacancies affect the fracture toughness of the Laves phases significantly

  19. Unified theoretical approach for binary and ternary alloys via an effective field theory

    Science.gov (United States)

    Freitas, Augusto S.; de Albuquerque, Douglas F.

    2016-01-01

    We describe the phase diagram of binary and ternary disordered alloys using the mixed-bond Ising model, via effective field theory (EFT). For example, we describe the Fe-Al alloy as a mixed-bond system instead of as diluted alloy. In our approach, we obtain the percolation threshold for some lattices and describe the lines of ferro-paramagnetic transition of Fe-Al, Fe-Mn, Fe-Mn-Al and Fe-Ni-Mn alloys and we obtain good agreement with the experimental data.

  20. Thermodynamic analysis of the Ga-Pb binary system

    Directory of Open Access Journals (Sweden)

    Manasijević Dragan

    2003-01-01

    Full Text Available Thermodynamic properties of binary Ga-Pb alloys were investigated experimentally and analytically. Quantitative differential thermal analysis was used for determination of integral mixing enthalpies for the gallium-reach alloys, at the constant temperature inside the liquid two-phase region. Calculation of gallium activities in the temperature range of 800-1000 K was done using Chou’s calculation model developed for binary systems with miscibility gap existence.

  1. Microstructure and properties of Mg-Al binary alloys

    Institute of Scientific and Technical Information of China (English)

    ZHENG Wei-chao; LI Shuang-shou; TANG Bin; ZENG Da-ben

    2006-01-01

    The effects of different amounts of added Al, ranging from 1% to 9%, on the microstructure and properties of Mg-Al binary alloys were investigated. The results showed that when the amount of added Al is less than 5%, the grain size of the Mg-Al binary alloys decreases dramatically from 3 097 μm to 151 μm with increasing addition of Al. Further addition of Al up to 9% makes the grain size decrease slowly to 111 μm. The α-Mg dendrite arms are also refined. Increasing the amount of added Al decreases the hot cracking susceptibility of the Mg-Al binary alloys remarkably, and enhances the micro-hardness of the α-Mg matrix.

  2. Microstructure and properties of Mg-Al binary alloys

    Directory of Open Access Journals (Sweden)

    ZHENG Wei-chao

    2006-11-01

    Full Text Available The effects of different amounts of added Al, ranging from 1 % to 9 %, on the microstructure and properties of Mg-Al binary alloys were investigated. The results showed that when the amount of added Al is less than 5%, the grain size of the Mg-Al binary alloys decreases dramatically from 3 097 μm to 151 μm with increasing addition of Al. Further addition of Al up to 9% makes the grain size decrease slowly to 111 μm. The α-Mg dendrite arms are also refined. Increasing the amount of added Al decreases the hot cracking susceptibility of the Mg-Al binary alloys remarkably, and enhances the micro-hardness of the α-Mg matrix.

  3. Nitriding behavior of Ni and Ni-based binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fonovic, Matej

    2015-01-15

    precipitate-free microstructure known as expanded austenite or S-phase, which can enhance surface hardness, fatigue properties and corrosion properties.Nitriding of multicomponent Ni-based alloys is usually applied in the industry. Nevertheless, the understanding of nitriding is mostly based on phenomenological research and experience. Thereby there is still absence of complete understanding of nitriding of Ni-based alloys, which requires further detailed investigations. Since studying the nitrided multicomponent alloys is complicated, in this thesis fundamental investigations were performed on pure nickel and binary Ni-based model alloys.This thesis focuses on the nitriding behavior of pure nickel, which will result with an thermodynamic evaluation of the Ni-N system. Furthermore, deeper insights in the nitriding behavior of the binary Ni-based alloys is obtained upon nitriding Ni-4 wt.% Ti and Ni-2 wt.% Ti (Ni-5 at.% Ti and Ni-2.5 at.% Ti) alloys. Thereby, the development of large residual macrostresses parallel to the surface of the specimen is related with the N concentration gradient in the nitrided zone.

  4. Theoretical Investigation of Binary Eutectic Alloy Nanoscale Phase Diagrams

    OpenAIRE

    Boswell-Koller, Cosima Nausikaa

    2012-01-01

    Recently, embedded binary eutectic alloy nanostructures (BEANs) have drawn some attention. A previously calculated equilibrium structure map predicts four possible nanocrystal alloy morphologies: phase-separated, bi-lobe, core-shell and inverse coreshellgoverned by two dimensionless interface energy parameters. The shape of the bilobe nanoparticles is obtained by nding the surface area of all interfaces that minimizes the overall energy, while also maintaining mechanical equilibrium at the tr...

  5. Linear Stability of Binary Alloy Solidification for Unsteady Growth Rates

    Science.gov (United States)

    Mazuruk, K.; Volz, M. P.

    2010-01-01

    An extension of the Mullins and Sekerka (MS) linear stability analysis to the unsteady growth rate case is considered for dilute binary alloys. In particular, the stability of the planar interface during the initial solidification transient is studied in detail numerically. The rapid solidification case, when the system is traversing through the unstable region defined by the MS criterion, has also been treated. It has been observed that the onset of instability is quite accurately defined by the "quasi-stationary MS criterion", when the growth rate and other process parameters are taken as constants at a particular time of the growth process. A singular behavior of the governing equations for the perturbed quantities at the constitutional supercooling demarcation line has been observed. However, when the solidification process, during its transient, crosses this demarcation line, a planar interface is stable according to the linear analysis performed.

  6. Magnetostrictive properties of sputtered binary Tb-Fe and pseudo-binary (Tb-Dy)-Fe alloy films

    International Nuclear Information System (INIS)

    Magnetostriction (λ=λ parallel -λ perpendicularto) and other magnetic properties have been investigated for sputtered TbxFe100-x (5≤x≤60) and (Tb1-yDyy)42Fe58 (0≤y≤1) alloy systems. These films exhibited an amorphous structure except for x-6 at x=33, corresponding to the composition of TbFe2 Laves phase, while that at 1 kOe exhibited a maximum of about 220 x 10-6 at x=42. In the pseudo-binary alloy system, the dependence of λ on the substitution of Dy was very similar to that of bulk data, implying a similarity of atomic short-range ordering between amorphous and crystalline (Tb-Dy)-Fe samples. The substrate temperature during the sputtering much influences upon the λ measured below 7 kOe. The maximum magnetostriction for both Tb33Fe67 and (Tb0.3Dy0.7)33Fe67 films were obtained at the substrate temperatures of about 400 and 300 C, respectively. A remarkable aging effect was found for the pseudo-binary alloy films and not for the binary alloy films. (orig.)

  7. Planets in evolved binary systems

    CERN Document Server

    Perets, Hagai B

    2010-01-01

    Exoplanets are typically thought to form in protoplanetary disks left over from protostellar disk of their newly formed host star. However, additional planetary formation and evolution routes may exist in old evolved binary systems. Here we discuss the implications of binary stellar evolution on planetary systems. In these binary systems stellar evolution could lead to the formation of symbiotic stars, where mass is lost from one star and could be transferred to its binary companion, and may form an accretion disk around it. This raises the possibility that such a disk could provide the necessary environment for the formation of a new, second generation of planets in both circumstellar or circumbinary configurations. Pre-existing first generation planets surviving the post-MS evolution of such systems would be dynamically effected by the mass loss in the systems and may also interact with the newly formed disk. Second generation planetary systems should be typically found in white dwarf binary systems, and ma...

  8. Vertical solidification of dendritic binary alloys

    Science.gov (United States)

    Heinrich, J. C.; Felicelli, S.; Poirier, D. R.

    1991-01-01

    Three numerical techniques are employed to analyze the influence of thermosolutal convection on defect formation in directionally solidified (DS) alloys. The finite-element models are based on the Boussinesq approximation and include the plane-front model and two plane-front models incorporating special dendritic regions. In the second model the dendritic region has a time-independent volume fraction of liquid, and in the last model the dendritic region evolves as local conditions dictate. The finite-element models permit the description of nonlinear thermosolutal convection by treating the dendritic regions as porous media with variable porosities. The models are applied to lead-tin alloys including DS alloys, and severe segregation phenomena such as freckles and channels are found to develop in the DS alloys. The present calculations and the permeability functions selected are shown to predict behavior in the dendritic regions that qualitatively matches that observed experimentally.

  9. Evolution of Close Binary Systems

    Energy Technology Data Exchange (ETDEWEB)

    Yakut, K; Eggleton, P

    2005-01-24

    We collected data on the masses, radii, etc. of three classes of close binary stars: low-temperature contact binaries (LTCBs), near-contact binaries (NCBs), and detached close binaries (DCBs). They restrict themselves to systems where (1) both components are, at least arguably, near the Main Sequence, (2) the periods are less than a day, and (3) there is both spectroscopic and photometric analysis leading to reasonably reliable data. They discuss the possible evolutionary connections between these three classes, emphasizing the roles played by mass loss and angular momentum loss in rapidly-rotating cool stars.

  10. Bond strength of binary titanium alloys to porcelain.

    Science.gov (United States)

    Yoda, M; Konno, T; Takada, Y; Iijima, K; Griggs, J; Okuno, O; Kimura, K; Okabe, T

    2001-06-01

    The purpose of this study was to investigate the bond strength between porcelain and experimental cast titanium alloys. Eleven binary titanium alloys were examined: Ti-Cr (15, 20, 25 wt%), Ti-Pd (15, 20, 25 wt%), Ti-Ag (10, 15, 20 wt%), and Ti-Cu (5, 10 wt%). As controls, the bond strengths for commercially pure titanium (KS-50, Kobelco, Japan) and a high noble gold alloy (KIK, Ishifuku, Japan) were also examined. Castings were made using a centrifugal casting unit (Ticast Super R, Selec Co., Japan). Commercial porcelain for titanium (TITAN, Noritake, Japan) was applied to cast specimens. The bond strengths were evaluated using a three-point bend test according to ISO 9693. Since the elastic modulus value is needed to evaluate the bond strength, the modulus was measured for each alloy using a three-point bend test. Results were analyzed using one-way ANOVA/S-N-K test (alpha = 0.05). Although the elastic moduli of the Ti-Pd alloys were significantly lower than those of other alloys (p = 0.0001), there was a significant difference in bond strength only between the Ti-25Pd and Ti-15Ag alloys (p = 0.009). The strengths determined for all the experimental alloys ranged from 29.4 to 37.2MPa, which are above the minimum value required by the ISO specification (25 MPa).

  11. GRAIN-BOUNDARY PRECIPITATION UNDER IRRADIATION IN DILUTE BINARY ALLOYS

    Institute of Scientific and Technical Information of China (English)

    S.H. Song; Z.X. Yuan; J. Liu; R.G.Faulkner

    2003-01-01

    Irradiation-induced grain boundary segregation of solute atoms frequently bring about grain boundary precipitation of a second phase because of its making the solubility limit of the solute surpassed at grain boundaries. Until now the kinetic models for irradiation-induced grain boundary precipitation have been sparse. For this reason, we have theoretically treated grain boundary precipitation under irradiation in dilute binary alloys. Predictions ofγ'-Ni3Si precipitation at grain boundaries ave made for a dilute Ni-Si alloy subjected to irradiation. It is demonstrated that grain boundary silicon segregation under irradiation may lead to grain boundaryγ'-Ni3 Si precipitation over a certain temperature range.

  12. Discs in misaligned binary systems

    CERN Document Server

    Rawiraswattana, Krisada; Goodwin, Simon P

    2016-01-01

    We perform SPH simulations to study precession and changes in alignment between the circumprimary disc and the binary orbit in misaligned binary systems. We find that the precession process can be described by the rigid-disc approximation, where the disc is considered as a rigid body interacting with the binary companion only gravitationally. Precession also causes change in alignment between the rotational axis of the disc and the spin axis of the primary star. This type of alignment is of great important for explaining the origin of spin-orbit misaligned planetary systems. However, we find that the rigid-disc approximation fails to describe changes in alignment between the disc and the binary orbit. This is because the alignment process is a consequence of interactions that involve the fluidity of the disc, such as the tidal interaction and the encounter interaction. Furthermore, simulation results show that there are not only alignment processes, which bring the components towards alignment, but also anti-...

  13. Front tracking in the numerical simulation of binary alloy solidification

    Science.gov (United States)

    Simpson, James Edward

    2000-12-01

    A model for directional solidification in dilute binary alloys is presented. The energy equation is solved for the temperature field, while the species equation is solved for the solute distribution. Either the vorticity-vector potential formulation or the pressure-velocity formulation is used to solve the governing equations for the velocity field. The constitutive equations are solved using a fully transient scheme. A variety of fast numerical schemes for solving sparse systems are used in the solution procedure. A single domain approach is used for the solution scheme for the energy and concentration equations. The effects of phase-change (energy equation) and solute rejection at the advancing solid/liquid interface (concentration equation) are handled via the introduction of appropriate source terms. The numerical approach was validated by comparing numerical results to data from a series of experiments of the Bridgman growth of pure succinonitrile. These experiments were performed as part of this work and are explained in detail. The numerical results agree well with the experimental data in terms of interface shape, temperature and velocity data. The key contribution of this work is the investigation of the Bridgman crystal growth of bismuth-tin in support of NASA's MEPHISTO project. The simulations reported in this work are among the first fully transient simulations of the process; no simplifying steady state approximations were used. Results are obtained for Bi-Sn alloys at a variety of initial concentrations and gravity levels. For most of the work, the solid/liquid interface temperature is assumed to be constant. For the richer alloy (Bi-1.0 at.% Sn) the results indicate that a secondary convective cell, driven by solutal gradients, forms near the interface. The magnitude of the velocities in this cell increases with time, causing increasing solute segregation at the solid/liquid interface. At lower gravity levels, convection-induced segregation is

  14. A New Thermodynamic Calculation Method for Binary Alloys: Part I: Statistical Calculation of Excess Functions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The improved form of calculation formula for the activities of the components in binary liquids and solid alloys has been derived based on the free volume theory considering excess entropy and Miedema's model for calculating the formation heat of binary alloys. A calculation method of excess thermodynamic functions for binary alloys, the formulas of integral molar excess properties and partial molar excess properties for solid ordered or disordered binary alloys have been developed. The calculated results are in good agreement with the experimental values.

  15. Phase Stability, Kinetic Diagrams and Diffusion Path in High Temperature Oxidation of Binary Solid-Solution Alloys

    Institute of Scientific and Technical Information of China (English)

    Yan NIU; F. Gesmundo

    2003-01-01

    The phase diagrams of ternary systems involving two metal components and one oxidant are considered first, the limitations to their use is discussed in relation to the high temperature oxidation of binary alloys. Kinetic diagrams,which are useful to predict the conditions for the stability of the two mutually insoluble oxides as the external scale, are then calculated on the basis of thermodynamic and kinetic data concerning both the alloys and the oxides, assuming the validity of the parabolic rate law. A combination of the two types of diagrams provides a more detail information about the oxidation behavior of binary alloys. The calculation of the diffusion paths, which relate the oxidant pressure to the composition of the system in terms of the alloy components both in the alloy and in the scale during an initial stage of the reaction in the presence of the parabolic rate law, is finally developed.

  16. Superconducting state parameters of indium-based binary alloys

    Indian Academy of Sciences (India)

    A M Vora; Minal H Patel; P N Gajjar; A R Jani

    2002-05-01

    Our well-recognized pseudopotential is used to investigate the superconducting state parameters viz; electron–phonon coupling strength , Coulomb pseudopotentialµ *, transition temperature c, isotope effective exponent and interaction strength 0 for the In1-Zn and In1-Sn binary alloys. We have incorporated six different types of local field correction functions, proposed by Hartree, Taylor, Vashistha–Singwi, Ichimaru–Utsumi, Farid et al and Sarkar et al to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of the various exchange and correlation functions is concluded from the present study. The comparison with other such theoretical values is encouraging, which confirms the applicability of our model potential in explaining the superconducting state parameters of binary mixture.

  17. Discs in misaligned binary systems

    Science.gov (United States)

    Rawiraswattana, Krisada; Hubber, David A.; Goodwin, Simon P.

    2016-08-01

    We perform SPH simulations to study precession and changes in alignment between the circumprimary disc and the binary orbit in misaligned binary systems. We find that the precession process can be described by the rigid-disc approximation, where the disc is considered as a rigid body interacting with the binary companion only gravitationally. Precession also causes change in alignment between the rotational axis of the disc and the spin axis of the primary star. This type of alignment is of great important for explaining the origin of spin-orbit misaligned planetary systems. However, we find that the rigid-disc approximation fails to describe changes in alignment between the disc and the binary orbit. This is because the alignment process is a consequence of interactions that involve the fluidity of the disc, such as the tidal interaction and the encounter interaction. Furthermore, simulation results show that there are not only alignment processes, which bring the components towards alignment, but also anti-alignment processes, which tend to misalign the components. The alignment process dominates in systems with misalignment angle near 90°, while the anti-alignment process dominates in systems with the misalignment angle near 0° or 180°. This means that highly misaligned systems will become more aligned but slightly misaligned systems will become more misaligned.

  18. Mechanical alloying in immiscible alloy systems

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In recent years, mechanical alloying (MA) of immiscible alloy systems characterized by positive heat of mixing has been extensively investigated. The present article reviews the latest progress in MA of immiscible alloy systems including the mechanisms of non-equilibrium phase transformation and metastable phase formation of the MA-driven supersaturated solid solutions, amorphous phases and nanophase composites as well as their mechanical and physical properties related to those metastable phases.

  19. Numerical modelling of the binary alloys solidification with solutal undercooling

    Directory of Open Access Journals (Sweden)

    T. Skrzypczak

    2008-03-01

    Full Text Available In thc papcr descrip~ion of mathcmn~icaI and numerical modcl of binay alloy sot idification is prcscntcd. Mctal alloy consisting of maincomponent and solulc is introduced. Moving, sharp solidification rmnt is assumcd. Conaitulional undcrcooling phcnomcnon is tnkcn intoconsidcralion. As a solidifica~ionf ront advances, solutc is rcdistributcd at thc intcrfacc. Commonly, solutc is rejccted into Itlc liquid. whcrcit accumuIatcs into solittc boundary laycr. Depending on thc tcmpcrature gradient, such tiquid may be undcrcoolcd hclow its mclting point,cvcn though it is hot~crth an liquid at thc Front. This phcnomcnon is orten callcd constitutional or soIr~talu ndcrcool ing, to cmphasizc that itariscs from variations in solutal distribution or I iquid. An important conscqucncc of this accurnulntion of saIutc is that it can cause thc frontto brcak down into cclls or dendri~csT. his occurs bccausc thcrc is a liquid ahcad of thc front with lowcr solutc contcnt, and hcncc a highcrme1 ting tcmpcraturcs than liquid at thc front. In rhc papcr locarion and shapc of wndcrcoolcd rcgion dcpcnding on solidification pararnctcrsis discussed. Nurncrical mcthod basing on Fini tc Elelncnt Mctbod (FEM allowi~lgp rcdiction of breakdown of inoving planar front duringsolidification or binary alloy is proposed.

  20. Tides in asynchronous binary systems

    OpenAIRE

    Toledano, Oswaldo; Moreno, Edmundo; Koenigsberger, Gloria; Detmers, R.; Langer, Norbert

    2006-01-01

    Stellar oscillations are excited in non-synchronously rotating stars in binary systems due to the tidal forces. Tangential components of the tides can drive a shear flow which behaves as a differentially forced rotating structure in a stratified outer medium. In this paper we show that our single-layer approximation for the calculation of the forced oscillations yields results that are consistent with the predictions for the synchronization timescales in circular orbits. In addition, calibrat...

  1. Solid-liquid surface tensions of critical nuclei and nucleation barriers from a phase-field-crystal study of a model binary alloy using finite system sizes

    Science.gov (United States)

    Choudhary, Muhammad Ajmal; Kundin, Julia; Emmerich, Heike; Oettel, Martin

    2014-08-01

    Phase-field-crystal (PFC) modeling has emerged as a computationally efficient tool to address crystal growth phenomena on atomistic length and diffusive time scales. We use a two-dimensional phase-field-crystal model for a binary system based on Elder et al. [Phys. Rev. B 75, 064107 (2007), 10.1103/PhysRevB.75.064107] to study critical nuclei and their liquid-solid phase boundaries, in particular the nucleus size dependence of the liquid-solid interface tension as well as of the nucleation barrier. Critical nuclei are stabilized in finite systems of various sizes, however, the extracted interface tension as function of the nucleus radius r is independent of system size. We suggest a phenomenological expression to describe the dependence of the extracted interface tension on the nucleus radius r for the liquid-solid system. Moreover, the numerical PFC results show that this dependency can not be fully described by the nonclassical Tolman formula.

  2. Sn-Sb-Se based binary and ternary alloys for phase change memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Kyung-Min

    2008-10-28

    In this work, the effect of replacing Ge by Sn and Te by Se was studied for a systematic understanding and prediction of new potential candidates for phase change random access memories applications. The temperature dependence of the electrical/structural properties and crystallization kinetics of the Sn-Se based binary and Sn-Sb-Se based ternary alloys were determined and compared with those of the GeTe and Ge-Sb-Te system. The temperature dependence of electrical and structural properties were investigated by van der Pauw measurements, X-ray diffraction, X-ray reflectometry. By varying the heating rate, the Kissinger analysis has been used to determine the combined activation barrier for crystallization. To screen the kinetics of crystallization, a static laser tester was employed. In case of binary alloys of the type Sn{sub x}Se{sub 1-x}, the most interesting candidate is SnSe{sub 2} since it crystallizes into a single crystalline phase and has high electrical contrast and reasonably high activation energy for crystallization. In addition, the SnSe{sub 2}-Sb{sub 2}Se{sub 3} pseudobinary alloy system also might be sufficient for data retention due to their higher transition temperature and activation energy for crystallization in comparison to GeTe-Sb{sub 2}Te{sub 3} system. Furthermore, SnSe{sub 2}-Sb{sub 2}Se{sub 3} pseudobinary alloys have a higher crystalline resistivity. The desired rapid crystallization speed can be obtained for Sn{sub 1}Sb{sub 2}Se{sub 5} and Sn{sub 2}Sb{sub 2}Se{sub 7} alloys. (orig.)

  3. Finite element simulations of thermosolutal convection in vertical solidification of binary alloys

    Science.gov (United States)

    Heinrich, J. C.; Felicelli, S.

    1989-01-01

    Dendritic vertical solidification of a binary alloy is modeled using the finite element method to assess the effect of thermosolutal convection in macrosegregation. The mathematical model assumes steady-state solidification with a planar, undeformable surface defined by the dendrite tips and the eutectic isotherm. The dendritic region is assumed to advance at a constant solidification velocity v. The stability of the modeled system has been investigated and nonlinear calculations performed that show finger-like convection when the system is unstable. Results for lead-tin alloys show that when the system is unstable, convection is only significant in the uppermost part of the mush and is entirely driven by convection in the bulk fluid.

  4. Close Binary System GO Cyg

    CERN Document Server

    Ulas, B; Keskin, V; Kose, O; Yakut, K

    2011-01-01

    In this study, we present long term photometric variations of the close binary system \\astrobj{GO Cyg}. Modelling of the system shows that the primary is filling Roche lobe and the secondary of the system is almost filling its Roche lobe. The physical parameters of the system are $M_1 = 3.0\\pm0.2 M_{\\odot}$, $M_2 = 1.3 \\pm 0.1 M_{\\odot}$, $R_1 = 2.50\\pm 0.12 R_{\\odot}$, $R_2 = 1.75 \\pm 0.09 R_{\\odot}$, $L_1 = 64\\pm 9 L_{\\odot}$, $L_2 = 4.9 \\pm 0.7 L_{\\odot}$, and $a = 5.5 \\pm 0.3 R_{\\odot}$. Our results show that \\astrobj{GO Cyg} is the most massive system near contact binary (NCB). Analysis of times of the minima shows a sinusoidal variation with a period of $92.3\\pm0.5$ years due to a third body whose mass is less than 2.3$M_{\\odot}$. Finally a period variation rate of $-1.4\\times10^{-9}$ d/yr has been determined using all available light curves.

  5. Phase field modeling of multiple dendrite growth of AI-Si binary alloy under isothermal solidification

    Institute of Scientific and Technical Information of China (English)

    Sun Qiang; Zhang Yutuo; Cui Haixia; Wang Chengzhi

    2008-01-01

    Phase field method offers the prospect of being able to perform realistic numerical experiments on dendrite growth in metallic systems. In this study, the growth process of multiple dendrites in Ai-2-mole-%-Si binary alloy under isothermal solidification was simulated using phase field model. The simulation results showed the impingement of arbitrarily oriented crystals and the competitive growth among the grains during solidification. With the increase of growing time, the grains begin to coalesce and impinge the adjacent grains. When the dendrites start to impinge, the dendrite growth is obviously inhibited.

  6. Solidification of binary alloy in a finned enclosure from the bottom

    Energy Technology Data Exchange (ETDEWEB)

    Tan, F.L. [Nanyang Technological University, School of Mechanical and Aerospace Engineering, Singapore (Singapore)

    2009-01-15

    This paper presents experimental findings on the phenomenon of solidification of a binary alloy in a finned enclosure using aqueous ammonium chloride solution. Solidification experiments are carried out over a wide range of initial composition of binary alloy solution from hypoeutectic to hypereutectic concentration ranging from 8, 16 and 24% of ammonium chloride are discussed. An interesting ''snowing'' phenomenon is observed for the hypereutectic concentration in a finned enclosure. (orig.)

  7. Phase-field simulation of dendritic growth for binary alloys with complicate solution models

    Institute of Scientific and Technical Information of China (English)

    LI Xin-zhong; GUO Jing-jie; SU Yan-qing; WU Shi-ping; FU Heng-zhi

    2005-01-01

    A phase-field method for simulation of dendritic growth in binary alloys with complicate solution models was studied. The free energy densities of solid and liquid used to construct the free energy of a solidification system in the phase-field model were derived from the Calphad thermodynamic modeling of phase diagram. The dendritic growth of Ti-Al alloy with a quasi-sub regular solution model was simulated in both an isothermal and a nonisothermal regime. In the isothermal one, different initial solute compositions and melt temperatures were chosen.And in the non-isothermal one, release of latent heat during solidification was considered. Realistic growth patterns of dendrite are derived. Both the initial compositions and melt temperatures affect isothermal dendritic morphology and solute distributions much, especially the latter. Release of latent heat will cause a less developed structure of dendrite and a lower interfacial composition.

  8. Free energy change of off-eutectic binary alloys on solidification

    Science.gov (United States)

    Ohsaka, K.; Trinh, E. H.; Lin, J.-C.; Perepezko, J. H.

    1991-01-01

    A formula for the free energy difference between the undercooled liquid phase and the stable solid phase is derived for off-eutectic binary alloys in which the equilibrium solid/liquid transition takes place over a certain temperature range. The free energy change is then evaluated numerically for a Bi-25 at. pct Cd alloy modeled as a sub-subregular solution.

  9. Studies of corrosion behaviour in alkaline environment of binary Mg-Li alloys for plastic forming

    OpenAIRE

    M. Żmudzińska; A. Białobrzeski; K. Saja

    2011-01-01

    The article discusses studies and corrosion tests of binary Mg-Li alloys for plastic forming examined in an alkaline medium (5% NaClsolution) for the time of 0-144 hours. In short it can be stated that the increase of Li content in magnesium alloys from 3% to 9% increasesthe corrosion resistance of alloy (the lowest susceptibility to corrosion in NaCl solution showed Mg- Li9 alloy). Increasing the content ofLi in alloy to over 9% resulted in a significant increase of the susceptibility to cor...

  10. Studies of corrosion behaviour in alkaline environment of binary Mg-Li alloys for plastic forming

    Directory of Open Access Journals (Sweden)

    M. Żmudzińska

    2011-07-01

    Full Text Available The article discusses studies and corrosion tests of binary Mg-Li alloys for plastic forming examined in an alkaline medium (5% NaClsolution for the time of 0-144 hours. In short it can be stated that the increase of Li content in magnesium alloys from 3% to 9% increasesthe corrosion resistance of alloy (the lowest susceptibility to corrosion in NaCl solution showed Mg- Li9 alloy. Increasing the content ofLi in alloy to over 9% resulted in a significant increase of the susceptibility to corrosion.

  11. Studies of corrosion behaviour in acid environment of binary Mg-Li alloys for plastic forming

    Directory of Open Access Journals (Sweden)

    A. Białobrzeski

    2011-07-01

    Full Text Available The article discusses studies and corrosion tests of binary Mg-Li alloys for plastic forming examined in an acid medium (5% HCl solutionfor the time of 0-144 hours. In short it can be stated that corrosion of the examined Mg-Li alloys in 5% HCl solution proceeded in a similarmode in all the studied alloys, regardless of the lithium content.

  12. Studies of corrosion behaviour in acid environment of binary Mg-Li alloys for plastic forming

    OpenAIRE

    A. Białobrzeski; K. Saja; M. Żmudzińska

    2011-01-01

    The article discusses studies and corrosion tests of binary Mg-Li alloys for plastic forming examined in an acid medium (5% HCl solution)for the time of 0-144 hours. In short it can be stated that corrosion of the examined Mg-Li alloys in 5% HCl solution proceeded in a similarmode in all the studied alloys, regardless of the lithium content.

  13. The steady-state solution of dendritic growth from the undercooled binary alloy melt with the far field flow

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The steady-state dendritic growth from the undercooled binary alloy melt with the far field flow is considered. By neglecting the interface energy, interface kinetics and buoyancy effects in the system, we obtaine the steady-state solution for the case of the large Schmidt number, in terms of the multiple variable expansion method. The changes of the temperature and concentration fields, the morphology of the interface, the normalization parameter and the Peclet number of the system induced by uniform external flow are derived. The results show that, compared with the system of dendritic growth from undercooled pure melt, the convective flow in the system of growth from undercooled binary alloy has stronger effects on the morphology of the interface. Nevertheless, the shape of the interface still remains nearly a paraboloid.

  14. The steady-state solution of dendritic growth from the undercooled binary alloy melt with the far field flow

    Institute of Scientific and Technical Information of China (English)

    CHEN MingWen; WANG ZiDong; XU JianJun

    2009-01-01

    The steady-state dendritic growth from the undercooled binary alloy melt with the far field flow is considered.By neglecting the interface energy,interface kinetics and buoyancy effects in the system,we obtaine the steady-state solution for the case of the large Schmidt number,in terms of the multiple variable expansion method.The changes of thtemperature and concentration fields,the morphology of the interface,the normalization parameter and the Peclet number of the system induced by uniform external flow are derived.The results show that,compared with the system of dendritic growth from undercooled pure melt,the convective flow in the system of growth from undercooled binary alloy has stronger effects on the morphology of the interface.Nevertheless,the shape of the interface still remains nearly a paraboloid.

  15. Evolution of non-synchronized binary systems

    Institute of Scientific and Technical Information of China (English)

    黄润乾; 曾艺蓉

    2000-01-01

    A model for binary evolution is introduced which can determine whether the rotation of components is synchronized with the orbital motion, and can calculate the evolution of both the synchronized and non-synchronized binary systems. With this model, the evolution of a binary system consisting of a 9 M star and a 6 M star is studied with mass transfer Case B. The result shows that the synchronization of the rotational and orbital periods can be reached when the binary system is a detached system and before the occurrence of the first mass transfer. After the onset of the first mass transfer, the binary system becomes non-synchronized. The mass accepted component (the secondary) rotates faster with a period much smaller than that of the orbital motion.

  16. Evolution of non-synchronized binary systems

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A model for binary evolution is introduced which can determine whether the rotation of components is synchronized with the orbital motion, and can calculate the evolution of both the synchronized and non-synchronized binary systems. With this model, the evolution of a binary system consisting of a 9 M⊙ star and a 6 M⊙ star is studied with mass transfer Case B. The result shows that the synchronization of the rotational and orbital periods can be reached when the binary system is a detached system and before the occurrence of the first mass transfer. After the onset of the first mass transfer, the binary system becomes non-synchronized. The mass accepted component (the secondary) rotates faster with a period much smaller than that of the orbital motion.

  17. THERMODYNAMICS OF BINARY ALLOYS OF PHARMACEUTICAL ACTIVE IMIDAZOLE WITH O- PHENYLENEDIAMINE

    Directory of Open Access Journals (Sweden)

    Shekhar H.

    2012-04-01

    Full Text Available The present study describes the investigation of eutectic and non-eutectic alloys of imidazole (IM with o - Phenylenediamine (OPD. the solid-liquid equilibrium (SLE data determined by thaw melt method in the form of melting temperature with their corresponding composition construct the solid-liquid equilibrium phase diagram which suggests simple eutectic behaviour is followed by the binary system. The activity co-efficient model based on enthalpy of fusion was employed to calculate the excess partial and integral thermodynamic functions such as gE, hE and sE. These values help to predict the nature of molecular interaction, ordering and stability between the components. The spontaneity of mixing of eutectic and non eutectic alloys was discussed by the partial and integral mixing quantities ∆GM, ∆HM and ∆SM. Using Gibbs-Duhem equation the solution of partial molar heat of mixing, activity and activity coefficient of the component in the binary mix have been resolved.

  18. Numerical simulation of freckle formation in directional solidification of binary alloys

    Science.gov (United States)

    Felicelli, Sergio D.; Heinrich, Juan C.; Poirier, David R.

    1992-01-01

    A mathematical model of solidification is presented which simulates the formation of segregation models known as 'freckles' during directional solidification of binary alloys. The growth of the two-phase or dendritic zone is calculated by solving the coupled equations of momentum, energy, and solute transport, as well as maintaining the thermodynamic constraints dictated by the phase diagram of the alloy. Calculations for lead-tin alloys show that the thermosolutal convection in the dendritic zone during solidification can produce heavily localized inhomogeneities in the composition of the final alloy.

  19. Computer Simulation of Ordering and Atom Clustering in Aging Binary Al-Li Alloy

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-ling; CHEN Zheng; WANG Yong-xin; HU Ming-juan

    2004-01-01

    Ordering and atom clustering in aging binary Al-Li alloy has been investigated by computer simulation through calculating the long range order (lro.) parameter and composition deviation order parameter from single-site occupation probabilities of Li atom. The results show that when the alloy lies in metastable region in the phase diagram ordering and atom clustering occur simultaneously. As the composition of the alloy increases ordering occurs earlier than atom clustering gradually. When the alloy lies in instable region atom clustering takes place after the congruent ordering completes. It has also been found that the incubation period of the phase transformation is shortened as the composition increases.

  20. Ab initio atomistic thermodynamics study on the oxidation mechanism of binary and ternary alloy surfaces

    International Nuclear Information System (INIS)

    Utilizing a combination of ab initio density-functional theory and thermodynamics formalism, we have established the microscopic mechanisms for oxidation of the binary and ternary alloy surfaces and provided a clear explanation for the experimental results of the oxidation. We construct three-dimensional surface phase diagrams (SPDs) for oxygen adsorption on three different Nb-X(110) (X = Ti, Al or Si) binary alloy surfaces. On the basis of the obtained SPDs, we conclude a general microscopic mechanism for the thermodynamic oxidation, that is, under O-rich conditions, a uniform single-phase SPD (type I) and a nonuniform double-phase SPD (type II) correspond to the sustained complete selective oxidation and the non-sustained partial selective oxidation by adding the X element, respectively. Furthermore, by revealing the framework of thermodynamics for the oxidation mechanism of ternary alloys through the comparison of the surface energies of two separated binary alloys, we provide an understanding for the selective oxidation behavior of the Nb ternary alloy surfaces. Using these general microscopic mechanisms, one could predict the oxidation behavior of any binary and multi-component alloy surfaces based on thermodynamics considerations

  1. Ab initio atomistic thermodynamics study on the oxidation mechanism of binary and ternary alloy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shi-Yu, E-mail: buaasyliu@gmail.com [College of Physics and Electronic Information Science, Tianjin Normal University, Tianjin 300387 (China); Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Liu, Shiyang [Institute of Information Optics, Zhejiang Normal University, Jinhua, Zhejiang 321004 (China); Li, De-Jun [College of Physics and Electronic Information Science, Tianjin Normal University, Tianjin 300387 (China); Wang, Sanwu, E-mail: sanwu-wang@utulsa.edu [Department of Physics and Engineering Physics, The University of Tulsa, Tulsa, Oklahoma 74104 (United States); Guo, Jing; Shen, Yaogen, E-mail: meshen@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong (China)

    2015-02-14

    Utilizing a combination of ab initio density-functional theory and thermodynamics formalism, we have established the microscopic mechanisms for oxidation of the binary and ternary alloy surfaces and provided a clear explanation for the experimental results of the oxidation. We construct three-dimensional surface phase diagrams (SPDs) for oxygen adsorption on three different Nb-X(110) (X = Ti, Al or Si) binary alloy surfaces. On the basis of the obtained SPDs, we conclude a general microscopic mechanism for the thermodynamic oxidation, that is, under O-rich conditions, a uniform single-phase SPD (type I) and a nonuniform double-phase SPD (type II) correspond to the sustained complete selective oxidation and the non-sustained partial selective oxidation by adding the X element, respectively. Furthermore, by revealing the framework of thermodynamics for the oxidation mechanism of ternary alloys through the comparison of the surface energies of two separated binary alloys, we provide an understanding for the selective oxidation behavior of the Nb ternary alloy surfaces. Using these general microscopic mechanisms, one could predict the oxidation behavior of any binary and multi-component alloy surfaces based on thermodynamics considerations.

  2. Disjoining potential and grain boundary premelting in binary alloys

    Science.gov (United States)

    Hickman, J.; Mishin, Y.

    2016-06-01

    Many grain boundaries (GBs) in crystalline materials develop highly disordered, liquidlike structures at high temperatures. In alloys, this premelting effect can be fueled by solute segregation and can occur at lower temperatures than in single-component systems. A premelted GB can be modeled by a thin liquid layer located between two solid-liquid interfaces interacting by a disjoining potential. We propose a single analytical form of the disjoining potential describing repulsive, attractive, and intermediate interactions. The potential predicts a variety of premelting scenarios, including thin-to-thick phase transitions. The potential is verified by atomistic computer simulations of premelting in three different GBs in Cu-Ag alloys employing a Monte Carlo technique with an embedded atom potential. The disjoining potential has been extracted from the simulations by analyzing GB width fluctuations. The simulations confirm all shapes of the disjoining potential predicted by the analytical model. One of the GBs was found to switch back and forth between two (thin and thick) states, confirming the existence of thin-to-thick phase transformations in this system. The proposed disjoining potential also predicts the possibility of a cascade of thin-to-thick transitions caused by compositional oscillations (patterning) near solid-liquid interfaces.

  3. Electrical Resistivity of Na-K Binary Liquid Alloy Using Ab-Initio Pseudopotentials

    Institute of Scientific and Technical Information of China (English)

    Anil Thakur; P. K. Ahluwalia

    2005-01-01

    @@ The study of electrical resistivity of simple binary liquid alloy Na-K is presented as a function of concentration.Hard sphere diameters of sodium (Na) and potassium (K) are obtained through the inter ionic pair potentials evaluated using Troullier and Martins ab-initio pseudopotentials, which have been used to calculate partial structure factors S(q). The Ziman formula for calculating resistivity of binary liquid alloys has been used. Form factors are calculated using ab-initio pseudopotentials. The results suggest that the first principle approach for calculating pseudopotentials with in the frame work of Ziman formalism is quite successful in explaining the electrical resistivity data of compound forming binary liquid alloys.

  4. The Evolution of Compact Binary Star Systems

    Directory of Open Access Journals (Sweden)

    Konstantin A. Postnov

    2014-05-01

    Full Text Available We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs, neutron stars (NSs, and black holes (BHs. Mergings of compact-star binaries are expected to be the most important sources for forthcoming gravitational-wave (GW astronomy. In the first part of the review, we discuss observational manifestations of close binaries with NS and/or BH components and their merger rate, crucial points in the formation and evolution of compact stars in binary systems, including the treatment of the natal kicks, which NSs and BHs acquire during the core collapse of massive stars and the common envelope phase of binary evolution, which are most relevant to the merging rates of NS-NS, NS-BH and BH-BH binaries. The second part of the review is devoted mainly to the formation and evolution of binary WDs and their observational manifestations, including their role as progenitors of cosmologically-important thermonuclear SN Ia. We also consider AM CVn-stars, which are thought to be the best verification binary GW sources for future low-frequency GW space interferometers.

  5. Theory of freezing of alkali halides and binary alloys

    International Nuclear Information System (INIS)

    Using the basic equations of classical statistical mechanics relating the singlet densities rho1 and rho2 of a binary system to the three partial direct correlation functions csub(ij), a theory of freezing is developed. Though the theory is set up for arbitrary concentration, we focus on the freezing of the alkali halides. In particular, we show that periodic solutions of the equations for rho1 and rho2 can coexist with homogeneous solutions. The difference in free energy between periodic and homogeneous phases is built up in terms of (i) the volume difference and (ii) the Fourier components of rho1, rho2 and csub(ij). To lowest order, it is stressed that the freezing transition is determined by the charge-charge structure factor at the principal peak and by the compressibility. (author)

  6. Binary Magnesium Alloys: Searching for Novel Compounds by Computational Thermodynamics

    Science.gov (United States)

    Taylor, Richard; Curtarolo, Stefano; Hart, Gus

    2011-03-01

    Magnesium alloys are among the lightest structural materials and are of considerable technical interest. We use the high-throughput framework AFLOW to make T = 0 K ground state predictions by scanning a large set of known candidate structures for thermodynamic minima. The study presented here encompasses 34 Mg-X systems of interest (X=Al, Au, Ca, Cd, Cu, Fe, Ge, Hg, Ir, K, La, Pb, Pd, Pt, Mo, Na, Nb, Os, Rb, Re, Rh, Ru, Sc, Si, Sn, Sr, Ta, Tc, Ti, V, W, Y, Zn, Zr). Avenues for further investigation revealed by this study include stable phases found in addition to experimental phases and compound forming systems thought to be either immiscible or non-compound forming. The existence of potentially novel ordered phases presents new opportunities for materials design.

  7. Enthalpies of Formation of Noble Metal Binary Alloys Bearing Rh or Ir

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The modified embedded atom method proposed by authors has been applied to calculating the enthalpies of formationof random alloys and the ordered intermetallic compounds for noble metal binary systems bearing Rh or lr. The presentresults are in good agreement with those of Miedema theory, available experiments and the first-principles quantummechanics calculations. The present results indicate that Cu-Rh, Cu-lr, Ag-Rh, Ag-lr, Au-Rh, Au-lr, Pd-Rh and Pd-lrsystems are repulsive, however, Ni-Rh, Ni-lr, Pt-lr, Pt-Rh and Rh-lr systems form solid solutions and Ni-Rh, Ni-lrand Pt-Rh show ordering tendency.

  8. Diffusion in ordered binary solid systems

    International Nuclear Information System (INIS)

    This thesis contains contributions to the field of diffusion in ordered binary solid systems. An extensive experimental investigation of the self diffusion in CoGa is presented. The results of these diffusion measurements strongly suggest that a substantial part of the atomic migration is caused by a new type of defect. A quantitative description of the atomic displacements via this defect is given. Finally computer simulations are presented of diffusion and ordering in binary solid systems. (Auth.)

  9. Preparation of NiFe binary alloy nanocrystals for nonvolatile memory applications

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this work,an idea which applies binary alloy nanocrystal floating gate to nonvolatile memory application was introduced.The relationship between binary alloy’s work function and its composition was discussed theoretically.A nanocrystal floating gate structure with NiFe nanocrystals embedded in SiO2 dielectric layers was fabricated by magnetron sputtering.The micro-structure and composition deviation of the prepared NiFe nanocrystals were also investigated by TEM and EDS.

  10. Two-dimensional cellular automaton model for simulating structural evolution of binary alloys during solidification

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lin; ZHANG Cai-bei

    2006-01-01

    Two-dimensional cellular automaton(CA) simulations of phase transformations of binary alloys during solidification were reported. The modelling incorporates local concentration and heat changes into a nucleation or growth function, which is utilized by the automaton in a probabilistic fashion. These simulations may provide an efficient method of discovering how the physical processes involved in solidification processes dynamically progress and how they interact with each other during solidification. The simulated results show that the final morphology during solidification is related with the cooling conditions. The established model can be used to evaluate the phase transformation of binary alloys during solidification.

  11. Compressive creep behavior of Mg-Sn binary alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Mg-Sn based alloy is one of the potential alloys for application at elevated temperature. The compressive creep behavior of ageing-treated Mg-xSn (x=3%, 5%) alloys was investigated at the temperatures of 423 and 473 K and the stresses from 25 MPa to 35 MPa. When the tin content varies, the ageing-treated Mg-xSn alloys show quite different creep resistance, which are mainly attributed to the size and distribution of Mg2Sn phases in the ageing-treated Mg-xSn alloys. The calculated value of stress exponent,n=6.3, suggests that the compressive creep behavior of the ageing-treated Mg-5%Sn alloy is controlled by dislocation creep at the temperature of 473 K and the stresses from 25 MPa to 35 MPa.

  12. A thermodynamic assessment of the iron-lead binary system

    Energy Technology Data Exchange (ETDEWEB)

    Vaajamo, I., E-mail: Iina.Vaajamo@aalto.fi [Aalto University School of Chemical Technology, Metallurgical Thermodynamics and Modelling Research Group PL 16200, FI-00076 Aalto (Finland); Taskinen, P., E-mail: Pekka.Taskinen@aalto.fi [Aalto University School of Chemical Technology, Metallurgical Thermodynamics and Modelling Research Group PL 16200, FI-00076 Aalto (Finland)

    2011-09-20

    Highlights: {center_dot} Isothermal equilibration experiments of the Fe-Pb binary were conducted in a special quartz ampoule and analyzed with ICP and EPMA. {center_dot} The method enables to obtain two experimental points from each end of the phase diagram in one experiment. {center_dot} New experimental data of the Pb solubility to Fe(s) below the monotectic temperature was obtained. {center_dot} This study consists of the widest critical compilation of the literature data done of the Fe-Pb binary system done so far, corrected also some errors in previous assessments. {center_dot} More accurate thermodynamic description of the Fe-Pb binary and its phases were obtained. - Abstract: The thermodynamic properties and phase equilibria of the Fe-Pb binary system were assessed using the CALPHAD (CALculation of PHAse Diagrams) method based upon available literature data and results of isothermal equilibration experiments reported in this paper. The phase diagram and excess Gibbs energy values of the solution phases, namely the molten alloy and the {gamma}-fcc and {alpha}- and {delta}-bcc solid solutions were expressed using Redlich-Kister polynomials. The experimental data were fitted by a least squares method using the MTDATA software. Agreement between experimental and calculated values is good. In particular the description of the solubility of lead in iron below the monotectic temperature has been improved.

  13. Strontium As a Structure Modifier for Non-binary Al–Si Alloy

    Directory of Open Access Journals (Sweden)

    Barbora Bryksí Stunová

    2012-01-01

    Full Text Available This paper presents a study of the influence on the structure of AlSi10Mg alloy when 400 ppm of strontium is added. Not only changes in the morphology of eutectic silicon, but in particular changes in the morphology of the intermetallicphases are monitored, namely phases containing iron and magnesium. The effect of strontium on structural defects,namely cavities formation, is also observed. It was found, that in non-binary system Al–Si–Mg also intermetallic phases of magnesium are affected by addition of strontium: especially phase Mg2Si changes the morphology significantly fromunmodified to modified structure. Moreover, findings of other authors, that strontium has a negative effect on the levelof gas porosity and on the distribution of shrinkages, are also confirmed.

  14. Numerical simulation on rapid melting and nonequilibrium solidification of pure metals and binary alloys

    Institute of Scientific and Technical Information of China (English)

    惠希东; 陈国良; 杨院生; 胡壮麒

    2002-01-01

    A heat and mass transfer modelling containing phase transformation dynamics is made for pure metals and binary alloys under pulsed laser processing. The nonequilibrium effects of processing parameters and physical properties are evaluated on the melting and solidification of pure metals (Al, Cu, Fe and Ni) and Al-Cu alloys. It is shown that the energy intensity of laser beam and physical properties of metals and the solute concentration of alloys have important effect on the interface temperature, melting and solidification velocity, melting depth and non-equilibrium partition coefficient. This situation is resulted from the interaction of heat transfer, redistribution of solute, solute trapping and growth kinetics.

  15. Mechanical and corrosion properties of binary Mg-Dy alloys for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang Lei, E-mail: lei.yang@hzg.de [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Huang Yuanding; Peng Qiuming; Feyerabend, Frank; Kainer, Karl Ulrich; Willumeit, Regine; Hort, Norbert [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany)

    2011-12-15

    Microstructure, mechanical and corrosion properties of binary magnesium-dysprosium (Mg-5, 10, 15, 20 wt.% Dy) alloys were investigated for medical applications. In the as-cast condition, the distribution of Dy is quite inhomogeneous. Mg-10Dy alloy exhibits a moderate tensile and compression yield strength, and the best elongation and corrosion resistance. After T4 (solutionizing) treatment, the distribution of Dy becomes homogeneous. The tensile and compression yield strength of all Mg-Dy alloys decreases. The elongation remains unchanged, while the corrosion resistance is largely improved after T4 treatment.

  16. PREDICTION OF THE MIXING ENTHALPIES OF BINARY LIQUID ALLOYS BY MOLECULAR INTERACTION VOLUME MODEL

    Institute of Scientific and Technical Information of China (English)

    H.W.Yang; D.P.Tao; Z.H.Zhou

    2008-01-01

    The mixing enthalpies of 23 binary liquid alloys are calculated by molecular interaction volume model (MIVM), which is a two-parameter model with the partial molar infinite dilute mixing enthalpies. The predicted values are in agreement with the experimental data and then indicate that the model is reliable and convenient.

  17. Microstructure and corrosion behavior of binary titanium alloys with beta-stabilizing elements.

    Science.gov (United States)

    Takada, Y; Nakajima, H; Okuno, O; Okabe, T

    2001-03-01

    Binary titanium alloys with the beta-stabilizing elements of Co, Cr, Cu, Fe, Mn and Pd (up to 30%) and Ag (up to 45%) were examined through metallographic observation and X-ray diffractometry to determine whether beta phases that are advantageous for dental use could be retained. Corrosion behavior was also investigated electrochemically and discussed thermodynamically. Some cast alloys with Co, Cr, Fe, Mn, and Pd retained the beta phase, whereas those with Ag and Cu had no beta phase. In some alloys, an intermetallic compound formed, based on information from the phase diagram. The corrosion resistance deteriorated in the TiAg alloys because Ti2Ag and/or TiAg intermetallic compounds preferentially dissolved in 0.9% NaCl solution. On the other hand, the remaining titanium alloys became easily passive and revealed good corrosion resistance similar to pure titanium since their matrices seemed to thermodynamically form titanium oxides as did pure titanium.

  18. Grain boundary premelting and activated sintering in binary refractory alloys

    Science.gov (United States)

    Shi, Xiaomeng

    Quasi-liquid intergranular film (IGF) which has been widely observed in ceramic systems can persist into sub-solidus region whereby an analogy to Grain boundary (GB) premelting can be made. In this work, a grain boundary (GB) premelting/prewetting model in a metallic system was firstly built based on the Benedictus' model and computational thermodynamics, predicting that GB disordering can start at 60-85% of the bulk solidus temperatures in selected systems. This model quantitatively explains the long-standing mystery of subsolidus activated sintering in W-Pd, W-Ni, W-Co, W-Fe and W-Cu, and it has broad applications for understanding GB-controlled transport kinetics and physical properties. Furthermore, this study demonstrates the necessity of developing GB phase diagrams as a tool for materials design. Subsequently, Grain boundary (GB) wetting and prewetting in Ni-doped Mo are systematically evaluated via characterizing well-quenched specimens and thermodynamic modeling. In contrast to prior reports, the delta-NiMo phase does not wet Mo GBs in the solid state. In the solid-liquid two-phase region, the Ni-rich liquid wets Mo GBs completely. Furthermore, high-resolution transmission electron microscopy demonstrates that nanometer-thick quasi-liquid IGFs persist at GBs into the single-phase region where the bulk liquid phase is no longer stable; this is interpreted as a case of GB prewetting. An analytical thermodynamic model is developed and validated, and this model can be extended to other systems. Furthermore, the analytical model was refined based upon Beneditus' model with correction in determining interaction contribution of interfacial energy. A calculation-based GB phase diagram for Ni-Mo binary system was created and validated by comparing with GB diffusivities determined through a series of controlled sintering experiments. The dependence of GB diffusivity on doping level and temperature was examined and compared with model-predicted GB phase diagram. The

  19. Investigation of segregation for AlxIn1-x liquid binary alloys

    International Nuclear Information System (INIS)

    Segregation of AlxIn1-x liquid binary alloys is systematically investigated from the energetic point of view using the electronic theory of metals. The free energy of mixing is calculated at different thermodynamic states characterized by temperatures for the full range of concentration by using the perturbation approach. The interionic interaction is described by a local pseudopotential. This study enables us to predict the correct miscibility gap as well as critical temperature (T=1160 K) and critical concentration (x=0.5) of segregation for the concerned alloys. These results agree well with available experimental data. Most importantly, results of our calculations have precisely identified for the first time that, the volume dependent term of the energy of mixing is mostly responsible for the total energy of mixing to be positive, which is one of the most significant indicators of segregation of liquid metals in binary alloys

  20. The size-effect on the formation enthalpy of nanosized binary ti based alloy

    International Nuclear Information System (INIS)

    The effects of grain size and composition on the formation enthalpy of nano binary Ti-based alloy are investigated by taking the surface effect into account within the modified Miedema model. It is demonstrated that the formation enthalpy of binary Ti based alloy with nano grains is size-dependent and exhibits evident size-effects. The formation enthalpy increases with the size decrease, and its value turns from negative to positive at a critical size, which will weaken the thermal stability of the nano grains. Furthermore, the composition segregation taking place in the nano grains of the Ti based alloy is obvious when the grain size is less than 10 nm and the tendency of segregation is dependent on the surface formation enthalpy of nanoparticle. (authors)

  1. Materials corrosion of high temperature alloys immersed in 600C binary nitrate salt.

    Energy Technology Data Exchange (ETDEWEB)

    Kruizenga, Alan Michael; Gill, David Dennis; LaFord, Marianne Elizabeth

    2013-03-01

    Thirteen high temperature alloys were immersion tested in a 60/40 binary nitrate salt. Samples were interval tested up to 3000 hours at 600ÀC with air as the ullage gas. Chemical analysis of the molten salt indicated lower nitrite concentrations present in the salt, as predicted by the equilibrium equation. Corrosion rates were generally low for all alloys. Corrosion products were identified using x-ray diffraction and electron microprobe analysis. Fe-Cr based alloys tended to form mixtures of sodium and iron oxides, while Fe-Ni/Cr alloys had similar corrosion products plus oxides of nickel and chromium. Nickel based alloys primarily formed NiO, with chromium oxides near the oxide/base alloy interface. In625 exhibited similar corrosion performance in relation to previous tests, lending confidence in comparisons between past and present experiments. HA230 exhibited internal oxidation that consisted of a nickel/chromium oxide. Alloys with significant aluminum alloying tended to exhibit superior performance, due formation of a thin alumina layer. Soluble corrosion products of chromium, molybdenum, and tungsten were also formed and are thought to be a significant factor in alloy performance.

  2. Determination of thermodynamic properties of aluminum based binary and ternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Altıntas, Yemliha [Abdullah Gül University, Faculty of Engineering, Department of Materials Science and Nanotechnology, 38039, Kayseri (Turkey); Aksöz, Sezen [Nevşehir Hacı Bektaş Veli University, Faculty of Arts and Science, Department of Physics, 50300, Nevşehir (Turkey); Keşlioğlu, Kâzım, E-mail: kesli@erciyes.edu.tr [Erciyes University, Faculty of Science, Department of Physics, 38039, Kayseri (Turkey); Maraşlı, Necmettin [Yıldız Technical University, Faculty of Chemical and Metallurgical Engineering, Department of Metallurgical and Materials Engineering, 34210, Davutpaşa, İstanbul (Turkey)

    2015-11-15

    In the present work, the Gibbs–Thomson coefficient, solid–liquid and solid–solid interfacial energies and grain boundary energy of a solid Al solution in the Al–Cu–Si eutectic system were determined from the observed grain boundary groove shapes by measuring the thermal conductivity of the solid and liquid phases and temperature gradient. Some thermodynamic properties such as the enthalpy of fusion, entropy of fusion, the change of specific heat from liquid to solid and the electrical conductivity of solid phases at their melting temperature were also evaluated by using the measured values of relevant data for Al–Cu, Al–Si, Al–Mg, Al–Ni, Al–Ti, Al–Cu–Ag, Al–Cu–Si binary and ternary alloys. - Highlights: • The microstructure of the Al–Cu–Si eutectic alloy was observed through SEM. • The three eutectic phases (α-Al, Si, CuAl{sub 2}) have been determined by EDX analysis. • Solid–liquid and solid–solid interfacial energies of α-Al solution were determined. • ΔS{sub f},ΔH{sub M}, ΔC{sub P}, electrical conductivity of solid phases for solid Al solutions were determined. • G–T coefficient and grain boundary energy of solid Al solution were determined.

  3. Stability of multiplanet systems in binaries

    CERN Document Server

    Marzari, F

    2016-01-01

    When exploring the stability of multiplanet systems in binaries, two parameters are normally exploited: the critical semimajor axis ac computed by Holman and Wiegert (1999) within which planets are stable against the binary perturbations, and the Hill stability limit Delta determining the minimum separation beyond which two planets will avoid mutual close encounters. Our aim is to test whether these two parameters can be safely applied in multiplanet systems in binaries or if their predictions fail for particular binary orbital configurations. We have used the frequency map analysis (FMA) to measure the diffusion of orbits in the phase space as an indicator of chaotic behaviour. First we revisited the reliability of the empirical formula computing ac in the case of single planets in binaries and we find that, in some cases, it underestimates by 10-20% the real outer limit of stability. For two planet systems, the value of Delta is close to that computed for planets around single stars, but the level of chaoti...

  4. Planetary nebula progenitors that swallow binary systems

    CERN Document Server

    Soker, Noam

    2015-01-01

    I propose that some irregular `messy' planetary nebulae owe their morphologies to triple-stellar evolution where tight binary systems are tidally and frictionally destroyed inside the envelope of asymptotic giant branch (AGB) stars. The tight binary system might breakup with one star leaving the system. In an alternative evolution, one of the stars of the brook-up tight binary system falls toward the AGB envelope with low specific angular momentum, and drowns in the envelope. In a different type of destruction process the drag inside the AGB envelope causes the tight binary system to merge. This releases gravitational energy within the AGB envelope, leading to a very asymmetrical envelope ejection, with an irregular and `messy' planetary nebula as a descendant. The evolution of the triple-stellar system before destruction can be in a full common envelope evolution (CEE) or in a grazing envelope evolution (GEE). Both before and after destruction the system might lunch pairs of opposite jets. One pronounced sig...

  5. A Model for Contact Binary Systems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A model for contact binary systems is presented, which incorporates the following special features: a) The energy exchange between the components is based on the understanding that the energy exchange is due to the release of potential, kinetic and thermal energies of the exchanged mass. b) A special form of mass and angular momentum loss occurring in contact binaries is losses via the outer Lagrangian point. c) The effects of spin, orbital rotation and tidal action on the stellar structure as well as the effect of meridian circulation on the mixing of the chemical elements are considered. d) The model is valid not only for low-mass contact binaries but also for high-mass contact binaries. For illustration, we used the model to trace the evolution of a massive binary system consisting of one 12M⊙ and one 5M⊙ star. The result shows that the start and end of the contact stage fall within the semi-detached phase during which the primary continually transfers mass to the secondary. The time span of the contact stage is short and the mass transfer rate is very large. Therefore, the contact stage can be regarded as a special part of the semi-detached phase with a large mass transfer rate. Both mass loss through the outer Lagrangian point and oscillation between contact and semi-contact states can occur during the contact phase, and the effective temperatures of the primary and the secondary are almost equal.

  6. Gravitational wave background from binary systems

    International Nuclear Information System (INIS)

    Basic aspects of the background of gravitational waves and its mathematical characterization are reviewed. The spectral energy density parameter Ω(f), commonly used as a quantifier of the background, is derived for an ensemble of many identical sources emitting at different times and locations. For such an ensemble, Ω(f) is generalized to account for the duration of the signals and of the observation, so that one can distinguish the resolvable and unresolvable parts of the background. The unresolvable part, often called confusion noise or stochastic background, is made by signals that cannot be either individually identified or subtracted out of the data. To account for the resolvability of the background, the overlap function is introduced. This function is a generalization of the duty cycle, which has been commonly used in the literature, in some cases leading to incorrect results. The spectra produced by binary systems (stellar binaries and massive black hole binaries) are presented over the frequencies of all existing and planned detectors. A semi-analytical formula for Ω(f) is derived in the case of stellar binaries (containing white dwarfs, neutron stars or stellar-mass black holes). Besides a realistic expectation of the level of background, upper and lower limits are given, to account for the uncertainties in some astrophysical parameters such as binary coalescence rates. One interesting result concerns all current and planned ground-based detectors (including the Einstein Telescope). In their frequency range, the background of binaries is resolvable and only sporadically present. In other words, there is no stochastic background of binaries for ground-based detectors.

  7. Phonon dispersion in alkali metals and their equiatomic sodium-based binary alloys

    Institute of Scientific and Technical Information of China (English)

    Aditya M. VORA

    2008-01-01

    In the present article, the theoretical calcula-tions of the phonon dispersion curves (PDCs) of five alkali metals viz. Li, Na, K, Rb, Cs and their four equia-tomic sodium-based binary alloys viz. Na0.5Li0.5,Na0.5K0.5, Na0.5Rb0.5 and Na0.5Cs0.5 to second order in a local model potential is discussed in terms of the real-space sum of the Born yon Karman central force con-stants. Instead of the concentration average of the force constants of pure alkali metals, the pseudo-alloy-atom (PAA) is adopted to directly compute the force constants of the four equiatomic sodium based binary alloys and was successfully applied. The exchange and correlation functions due to the Hartree (H) and Ichimaru-Utsumi (IU) are used to investigate the influence of the screening effects. The phonon frequencies of alkali metals and their four equiatomic sodium-based binary alloys in the longit-udinal branch are more sensitive to the exchange and cor-relation effects in comparison with the transverse branches. The PDCs of pure alkali metals are found in qualitative agreement with the available experimental data. The frequencies in the longitudinal branch are sup-pressed rather due to IU-screening function than those due to static H-screening function.

  8. Atom probe study of Cu-segregation in thermal aging of binary Fe-Cu alloys

    International Nuclear Information System (INIS)

    Fe-Cu binary alloy is commonly used as a prototype model alloy for Pressurized Water Reactor (PWR) pressure vessel steels, especially for the study of radiation damage. This is because of the fact that Cu is one of the main solutes, segregation of which is known to cause major embrittlement in reactor pressure vessel (RPV) steels under nuclear radiation. Interestingly, similar solute segregation is often noticed in case of radiation-free long-term thermal aging experiments as well. Therefore, thermal aging experiment which is considerably simpler can be effectively utilized to study the solute segregation behaviour and emulate radiation-induced damage. With this objective, a series of binary Fe-Cu alloys with Cu concentration varying from 0.1 at. % - 1.4 at. % were prepared by vacuum arc melting. They were subsequently cold-rolled, followed by homogenization at 800 C and water quenching. The homogenized samples were then aged at 500 C for the following different durations: 1, 3, 5, 8, 25, 50 and 100 h. 3DAP is an indispensable tool to study solute segregation at this length scale, and the current study will present the results of a detailed 3DAP investigation of the evolution of the thermal damage in these binary prototype alloys. (author)

  9. VLSI binary multiplier using residue number systems

    Energy Technology Data Exchange (ETDEWEB)

    Barsi, F.; Di Cola, A.

    1982-01-01

    The idea of performing multiplication of n-bit binary numbers using a hardware based on residue number systems is considered. This paper develops the design of a VLSI chip deriving area and time upper bounds of a n-bit multiplier. To perform multiplication using residue arithmetic, numbers are converted from binary to residue representation and, after residue multiplication, the result is reconverted to the original notation. It is shown that the proposed design requires an area a=o(n/sup 2/ log n) and an execution time t=o(log/sup 2/n). 7 references.

  10. Gravitational wave background from binary systems

    CERN Document Server

    Rosado, Pablo A

    2011-01-01

    Basic aspects of the background of gravitational waves and its mathematical characterization are reviewed. The spectral energy density parameter $\\Omega(f)$, commonly used as a quantifier of the background, is derived for an ensemble of many identical sources emitting at different times and locations. For such an ensemble, $\\Omega(f)$ is generalized to account for the duration of the signals and of the observation, so that one can distinguish the resolvable and unresolvable parts of the background. The unresolvable part, often called confusion noise or stochastic background, is made by signals that cannot be either individually identified or subtracted out of the data. To account for the resolvability of the background, the overlap function is introduced. This function is a generalization of the duty cycle, which has been commonly used in the literature, in some cases leading to incorrect results. The spectra produced by binary systems (stellar binaries and massive black hole binaries) are presented over the ...

  11. Nonlinear Tides in Close Binary Systems

    CERN Document Server

    Weinberg, Nevin N; Quataert, Eliot; Burkart, Josh

    2011-01-01

    We study the excitation and damping of tides in close binary systems, accounting for the leading order nonlinear corrections to linear tidal theory. These nonlinear corrections include two distinct effects: three-mode nonlinear interactions and nonlinear excitation of modes by the time-varying gravitational potential of the companion. This paper presents the formalism for studying nonlinear tides and studies the nonlinear stability of the linear tidal flow. Although the formalism is applicable to binaries containing stars, planets, or compact objects, we focus on solar type stars with stellar or planetary companions. Our primary results include: (1) The linear tidal solution often used in studies of binary evolution is unstable over much of the parameter space in which it is employed. More specifically, resonantly excited gravity waves are unstable to parametric resonance for companion masses M' > 10-100 M_Earth at orbital periods P = 1-10 days. The nearly static equilibrium tide is, however, parametrically s...

  12. BROWN DWARF BINARIES FROM DISINTEGRATING TRIPLE SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Reipurth, Bo [Institute for Astronomy and NASA Astrobiology Institute University of Hawaii, 640 N. Aohoku Place, Hilo, HI 96720 (United States); Mikkola, Seppo, E-mail: reipurth@ifa.hawaii.edu, E-mail: Seppo.Mikkola@utu.fi [Tuorla Observatory, University of Turku, Väisäläntie 20, Piikkiö (Finland)

    2015-04-15

    Binaries in which both components are brown dwarfs (BDs) are being discovered at an increasing rate, and their properties may hold clues to their origin. We have carried out 200,000 N-body simulations of three identical stellar embryos with masses drawn from a Chabrier IMF and embedded in a molecular core. The bodies are initially non-hierarchical and undergo chaotic motions within the cloud core, while accreting using Bondi–Hoyle accretion. The coupling of dynamics and accretion often leads to one or two dominant bodies controlling the center of the cloud core, while banishing the other(s) to the lower-density outskirts, leading to stunted growth. Eventually each system transforms either to a bound hierarchical configuration or breaks apart into separate single and binary components. The orbital motion is followed for 100 Myr. In order to illustrate 200,000 end-states of such dynamical evolution with accretion, we introduce the “triple diagnostic diagram,” which plots two dimensionless numbers against each other, representing the binary mass ratio and the mass ratio of the third body to the total system mass. Numerous freefloating BD binaries are formed in these simulations, and statistical properties are derived. The separation distribution function is in good correspondence with observations, showing a steep rise at close separations, peaking around 13 AU and declining more gently, reaching zero at separations greater than 200 AU. Unresolved BD triple systems may appear as wider BD binaries. Mass ratios are strongly peaked toward unity, as observed, but this is partially due to the initial assumptions. Eccentricities gradually increase toward higher values, due to the lack of viscous interactions in the simulations, which would both shrink the orbits and decrease their eccentricities. Most newborn triple systems are unstable and while there are 9209 ejected BD binaries at 1 Myr, corresponding to about 4% of the 200,000 simulations, this number has grown to

  13. The Evolution of Relativistic Binary Progenitor Systems

    CERN Document Server

    Francischelli, G J; Brown, G E

    2001-01-01

    Relativistic binary pulsars, such as B1534+12 and B1913+16 are characterized by having close orbits with a binary separation of ~ 3 R_\\sun. The progenitor of such a system is a neutron star, helium star binary. The helium star, with a strong stellar wind, is able to spin up its compact companion via accretion. The neutron star's magnetic field is then lowered to observed values of about 10^{10} Gauss. As the pulsar lifetime is inversely proportional to its magnetic field, the possibility of observing such a system is, thus, enhanced by this type of evolution. We will show that a nascent (Crab-like) pulsar in such a system can, through accretion-braking torques (i.e. the "propeller effect") and wind-induced spin-up rates, reach equilibrium periods that are close to observed values. Such processes occur within the relatively short helium star lifetimes. Additionally, we find that the final outcome of such evolutionary scenarios depends strongly on initial parameters, particularly the initial binary separation a...

  14. Structural models for amorphous transition metal binary alloys

    International Nuclear Information System (INIS)

    A dense random packing of 445 hard spheres with two different diameters in a concentration ratio of 3 : 1 was hand-built to simulate the structure of amorphous transition metal-metalloid alloys. By introducing appropriate pair potentials of the Lennard-Jones type, the structure is dynamically relaxed by minimizing the total energy. The radial distribution functions (RDF) for amorphous Fe0.75P0.25, Ni0.75P0.25, Co0.75P0.25 are obtained and compared with the experimental data. The calculated RDF's are resolved into their partial components. The results indicate that such dynamically constructed models are capable of accounting for some subtle features in the RDF of amorphous transition metal-metalloid alloys

  15. Phase-field simulations of solidification of AI-Cu binary alloys

    Institute of Scientific and Technical Information of China (English)

    龙文元; 蔡启舟; 陈立亮; 魏伯康

    2004-01-01

    The dendrite growth process during the solidification of the Al-4.5 %Cu binary alloy was simulated using the phase-field model, proposed by Kim et al. Solute diffusion equation and heat transfer equation were solved simultaneously. The effects of the noise on the dendrite growth, solute and temperature profile in the undercooled alloy melt were investigated. The results indicate that the noise can trigger the growth of the secondary arms, and increase the highest temperature and solute concentration, but not influence the tip operating state. The solute and temperature gradients in the tip are the highest.

  16. Crossover scaling of wavelength selection in directional solidification of binary alloys.

    Science.gov (United States)

    Greenwood, Michael; Haataja, Mikko; Provatas, And Nikolas

    2004-12-10

    We simulate cellular and dendritic growth in directional solidification in dilute binary alloys using a phase-field model solved with adaptive-mesh refinement. The spacing of primary branches is examined for a wide range of thermal gradients and alloy compositions and is found to undergo a maximum as a function of pulling velocity, in agreement with experimental observations. We demonstrate that wavelength selection is unambiguously described by a nontrivial crossover scaling function from the emergence of cellular growth to the onset of dendritic fingers. This result is further validated using published experimental data, which obeys the same scaling function.

  17. Special quasirandom structures for binary/ternary group IV random alloys

    KAUST Repository

    Chroneos, Alexander I.

    2010-06-01

    Simulation of defect interactions in binary/ternary group IV semiconductor alloys at the density functional theory level is difficult due to the random distribution of the constituent atoms. The special quasirandom structures approach is a computationally efficient way to describe the random nature. We systematically study the efficacy of the methodology and generate a number of special quasirandom cells for future use. In order to demonstrate the applicability of the technique, the electronic structures of E centers in Si1-xGex and Si1-x -yGexSny alloys are discussed for a range of nearest neighbor environments. © 2010 Elsevier B.V. All rights reserved.

  18. Enthalpies of mixing in binary Fe-Sb, Ce-Fe and ternary Ce-Fe-Sb liquid alloys

    Energy Technology Data Exchange (ETDEWEB)

    Usenko, Natalia; Kotova, Natalia [Taras Shevchenko National Univ., Kyiv (Ukraine). Dept. of Chemistry; Ivanov, Michael; Berezutski, Vadim [National Academy of Sciences, Kyiv (Ukraine). I. Frantsevich Institute for Problems of Materials Science

    2016-01-15

    The enthalpies of mixing in liquid alloys in the binary Fe-Sb, Ce-Fe and ternary Ce-Fe-Sb systems were determined over a wide range of composition by means of isoperibolic calorimetry in the temperature range 1600-1830 K. The minimum values of the integral enthalpy of mixing (ΔH{sub min}) were determined to be (-2.32 ± 0.22) kJ . mol{sup -1} at x{sub Sb} = 0.5 in the Fe-Sb system, and (-0.97 ± 0.19) kJ . mol{sup -1} at x{sub Ce} = 0.35 in the Ce-Fe system. The enthalpies of mixing in liquid ternary Ce-Fe-Sb alloys were found to increase smoothly from the binary boundary systems Ce-Fe and Fe-Sb towards the Ce-Sb system, reaching the minimum value of (-107.5 ± 3.6) kJ . mol{sup -1} in the vicinity of the phase CeSb.

  19. Correlation between liquid structure and glass forming ability in glassy Ag-based binary alloys

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The atomic structures of liquid Ag-based binary alloys have been investigated in the solidification process by means of X-ray diffraction. The results of liquid structure show that there is a break point in the mean nearest neighbor distance r1 and the coordination number Nmin for glass-forming liquid, while the correlation radius rc and the coordination number Nmin display a monotone variational trend above the break point. It means glass-forming liquids have a steady changing in structure above liquidus and more inhomogeneous state at liquidus. We conclude that there is a strong correlation between liquid structure and glass forming ability in Ag-based binary alloys.

  20. Precipitation behavior of B2-like particles in Fe-Cu binary alloy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The precipitation behavior in Fe-Cu binary alloy was investigated under transmission electron microscope (TEM) during aging at 650℃ for the time range of to 300 h. In addition to the zones with higher copper content and -Cu were observed, a metastable phase with B2-like structure was found in the early stage of the precipitation process, which is quite different from the equilibrium copper phase shown inthe Fe-Cu binary phase diagram and has perfect coherent relationship to the -Fe matrix. The appearance of B2-like structure is very important concerning the mechanism of aging strengthening effect and mechanical properties of corresponding engineering steels and alloys containing copper.

  1. Subthreshold swing minimization of cylindrical tunnel FET using binary metal alloy gate

    Science.gov (United States)

    Dash, Sidhartha; Sahoo, Girija Shankar; Mishra, Guru Prasad

    2016-03-01

    In this work, we have developed a two-dimensional (2-D) analytical drain current model for cylindrical-gate tunnel FET structure with linearly graded binary metal alloy gate. The surface potential of the proposed model is determined using the solution of 2-D Poisson's equation with suitable boundary conditions. Further it paves way for the calculation of other analog parameters such as shortest tunneling distance, drain current, threshold voltage and subthreshold swing (SS). The introduction of linearly modulated work-function of binary alloy optimizes the subthreshold swing by ∼10 mV/decade as compared to conventional cylindrical-gate tunnel FET devices without degrading the drain current and threshold voltage performance. Also the present model shows the reduction in SS with down-scaling of gate oxide thickness and silicon pillar diameter. The analytical results are found to be synonymous with the results of Synopsys TCAD device simulator.

  2. Phase-field simulation of dendritic growth in a binary alloy with thermodynamics data

    Institute of Scientific and Technical Information of China (English)

    Long Wen-Yuan; Xia Chun; Xiong Bo-Wen; Fang Li-Gao

    2008-01-01

    This paper simulates the dendrite growth process during non-isothermal solidification in the A1-Cu binary alloy by using the phase-field model. The heat transfer equation is solved simultaneously. The thermodynamic and kinetic parameters are directly obtained from existing database by using the Calculation of Phase Diagram (CALPHAD)method. The effects of the latent heat and undercooling on the dendrite growth, solute and temperature profile during the solidification of binary alloy are investigated. The results indicate that the dendrite growing morphologies could be simulated realistically by linking the phase-field method to CALPHAD. The secondary arms of solidification dendritic are better developed with the increase of undercooling. Correspondingly, the tip speed and the solute segregation in solid-liquid interface increase, but the tip radius decreases.

  3. The Geometry of Slow Structural Fluctuations in a Supercooled Binary Alloy

    OpenAIRE

    Pedersen, Ulf Rørbæk; Schrøder, Thomas; Dyre, J.C.; Harrowell, Peter

    2009-01-01

    The liquid structure of a glass-forming binary alloy is studied using molecular dynamics simulations. The analysis combines common neighbour analysis with the geometrical approach of Frank and Kasper to establish that the supercooled liquid contains extended clusters characterised by the same short range order as the crystal. Fluctuations in these clusters exhibit strong correlations with fluctuations in the inherent structure energy. The steep increase in the heat capacity on cooling is, thu...

  4. Nonlinear equations on controlling interface patterns during solidification of a dilute binary alloy

    Institute of Scientific and Technical Information of China (English)

    王自东; 周永利; 常国威; 胡汉起

    1999-01-01

    In nonequilibrium nonlinear region, by assuming that there is local equilibrium at the solid/liquid interface, and considering that curvature, temperature and composition at the solid/liquid interface which are related to perturbation amplitude are nonlinear, nonlinear equations of the time dependence of the perturbation amplitude of the solid/liquid interface during solidification of a dilute binary alloy are established. Crystal growth from nonsteady state to steady state can be controlled by these nonlinear equations.

  5. Quantification of tin and lead in binary alloys using voltammetry of immobilized microparticles

    OpenAIRE

    Arjmand Gholenji, Farzin; Adriaens, Annemie

    2011-01-01

    Voltammetry of immobilized microparticles (VMP) has been used in this work for the quantitative determination of tin and lead particles in their binary alloys. Carbon paste electrodes, which contained small amounts of tin and lead or their mixtures, were used as working electrodes and square wave voltammograms of each electrode were recorded. Quantification was performed using optimum experimental conditions, obtained by an experimental design technique. The calibration was made by measuring ...

  6. Dynamics and Habitability in Binary Star Systems

    CERN Document Server

    Eggl, Siegfried; Pilat-Lohinger, Elke

    2014-01-01

    Determining planetary habitability is a complex matter, as the interplay between a planet's physical and atmospheric properties with stellar insolation has to be studied in a self consistent manner. Standardized atmospheric models for Earth-like planets exist and are commonly accepted as a reference for estimates of Habitable Zones. In order to define Habitable Zone boundaries, circular orbital configurations around main sequence stars are generally assumed. In gravitationally interacting multibody systems, such as double stars, however, planetary orbits are forcibly becoming non circular with time. Especially in binary star systems even relatively small changes in a planet's orbit can have a large impact on habitability. Hence, we argue that a minimum model for calculating Habitable Zones in binary star systems has to include dynamical interactions.

  7. Short-range order and its effect on the electronic structure of binary alloys: CuZn - a case study

    Indian Academy of Sciences (India)

    Abhijit Mookerjee; Kartick Tarafder; Atisdipankar Chakrabarti; Kamal Krishna Saha

    2008-02-01

    We discuss an application of the generalized augmented space method introduced by one of us combined with the recursion method of Haydock et al (GASR) to the study of electronic structure and optical properties of random binary alloys. As an example, we have taken the 50-50 CuZn alloy, where neutron scattering indicates the existence of short-range order.

  8. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Haghighipour, Nader [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Kaltenegger, Lisa [MPIA, Koenigstuhl 17, Heidelberg, D-69117 (Germany)

    2013-11-10

    We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results.

  9. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

    International Nuclear Information System (INIS)

    We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results

  10. Complex Binary Number System Algorithms and Circuits

    CERN Document Server

    Jamil, Tariq

    2013-01-01

    This book is a compilation of the entire research work on the topic of Complex Binary Number System (CBNS) carried out by the author as the principal investigator and members of his research groups at various universities during the years 1992-2012. Pursuant to these efforts spanning several years, the realization of CBNS as a viable alternative to represent complex numbers in an 'all-in-one' binary number format has become possible and efforts are underway to build computer hardware based on this unique number system. It is hoped that this work will be of interest to anyone involved in computer arithmetic and digital logic design and kindle renewed enthusiasm among the engineers working in the areas of digital signal and image processing for developing newer and efficient algorithms and techniques incorporating CBNS.

  11. Coalescence of Magnetized Binary Neutron Star Systems

    Science.gov (United States)

    Motl, Patrick M.; Anderson, Matthew; Lehner, Luis; Liebling, Steven L.; Neilsen, David; Palenzuela, Carlos; Ponce, Marcelo

    2015-01-01

    We present simulations of the merger of binary neutron star systems calculated with full general relativity and incorporating the global magnetic field structure for the stars evolved with resistive magnetohydrodynamics. Our simulation tools have recently been improved to incorporate the effects of neutrino cooling and have been generalized to allow for tabular equations of state to describe the degenerate matter. Of particular interest are possible electromagnetic counterparts to the gravitational radiation that emerges from these systems. We focus on magnetospheric interactions that ultimately tap into the gravitational potential energy of the binary to power a Poynting flux and deposition of energy through Joule heating and magnetic reconnection. We gratefully acknowledge the support of NASA through the Astrophysics Theory Program grant NNX13AH01G.

  12. On the universality of Suzuki segregation in binary Mg alloys from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Xiang-Yuan, E-mail: carl.cui@sydney.edu.au [Centre for Microscopy and Microanalysis, and School of Aerospace, Mechanical, Mechatronic Engineering, The University of Sydney, New South Wales 2006 (Australia); Yen, Hung-Wei; Zhu, Su-Qin [Centre for Microscopy and Microanalysis, and School of Aerospace, Mechanical, Mechatronic Engineering, The University of Sydney, New South Wales 2006 (Australia); Zheng, Rongkun [School of Physics, The University of Sydney, New South Wales 2006 (Australia); Ringer, Simon P., E-mail: simon.ringer@sydney.edu.au [Centre for Microscopy and Microanalysis, and School of Aerospace, Mechanical, Mechatronic Engineering, The University of Sydney, New South Wales 2006 (Australia)

    2015-01-25

    Highlights: • We demonstrate that the attractive Suzuki segregation is not a universal phenomenon. • Not all segregated solutes need to overcome energy barriers to reach the stacking fault regions. • These findings advance our understanding on the interactions between point and extended defects. • Our results would be useful for stacking fault engineering. - Abstract: It has been often believed that substitutional solute atoms undergo preferential segregation to stacking faults (Suzuki effect). Here, density functional theory calculations reveal a rather diverse spatial distribution of the alloying atoms with respect to faults in binary Mg alloys. Interestingly, while some solutes encounter energy barriers when approaching faults, there is almost no barrier for Al and Sn. These findings advance our understanding concerning the interaction between solutes and extended defects, and provide guidance for stacking fault engineering in Mg alloys.

  13. On the universality of Suzuki segregation in binary Mg alloys from first principles

    International Nuclear Information System (INIS)

    Highlights: • We demonstrate that the attractive Suzuki segregation is not a universal phenomenon. • Not all segregated solutes need to overcome energy barriers to reach the stacking fault regions. • These findings advance our understanding on the interactions between point and extended defects. • Our results would be useful for stacking fault engineering. - Abstract: It has been often believed that substitutional solute atoms undergo preferential segregation to stacking faults (Suzuki effect). Here, density functional theory calculations reveal a rather diverse spatial distribution of the alloying atoms with respect to faults in binary Mg alloys. Interestingly, while some solutes encounter energy barriers when approaching faults, there is almost no barrier for Al and Sn. These findings advance our understanding concerning the interaction between solutes and extended defects, and provide guidance for stacking fault engineering in Mg alloys

  14. Modelling of binary alloy solidification in the MEPHISTO experiment

    Science.gov (United States)

    Leonardi, Eddie; de Vahl Davis, Graham; Timchenko, Victoria; Chen, Peter; Abbaschian, Reza

    2004-05-01

    A modified enthalpy method was used to numerically model experiments on solidification of a bismuth-tin alloy which were performed during the 1997 flight of the MEPHISTO-4 experiment on the US Space Shuttle Columbia. This modified enthalpy method was incorporated into an in-house code SOLCON and a commercial CFD code CFX; Soret effect was taken into account by including an additional thermo-diffusion term into the solute transport equation and the effects of thermal and solutal convection in the microgravity environment and of concentration-dependent melting temperature on the phase change processes were also included. In this paper an overview of the results obtained as part of MEPHISTO project is presented. The numerical solutions are compared with actual microprobe results obtained from the MEPHISTO experiment. To cite this article: E. Leonardi et al., C. R. Mecanique 332 (2004).

  15. Properties of planets in binary systems. The role of binary separation

    OpenAIRE

    Desidera, S.; Barbieri, M.

    2006-01-01

    The statistical properties of planets in binaries were investigated. Any difference to planets orbiting single stars can shed light on the formation and evolution of planetary systems. As planets were found around components of binaries with very different separation and mass ratio, it is particularly important to study the characteristics of planets as a function of the effective gravitational influence of the companion. A compilation of planets in binary systems was made; a search for compa...

  16. Thermodynamic assessment of the Bi-Mg binary system

    Institute of Scientific and Technical Information of China (English)

    Chunju NIU; Changrong LI; Zhenmin DU; Cuiping GUO; Yongjuan JING

    2012-01-01

    The Bi-Mg binary system had been assessed by adopting the ionic melt and the modified quasi-chemical models to describe the liquid phase with short range ordering behavior.In general considerations of the development of the thermodynamic database of the multi-component Mg-based alloys and the consistency of the thermodynamic models of the related phases,the Gibbs energy descriptions of all the phases in the Bi-Mg binary system were reasonably re-modeled and critically re-assessed in the present work.Especially for the liquid phase,the associate model was used with the constituent species Bi,Mg and Bi2Mg3.The Mg-rich terminal phase hcp_A3 was modeled as a substitutional solution following Redlich-Kister equation and the Bi-rich terminal phase Rhombohedral_A7 was treated as a pure Bi substance since the extremely small solubility of Mg in Bi. The low and high temperature nonstoichiometric compounds β-Bi2Mg3 and α-Bi2Mg3 were described by the sublattice models (Bi,Va)2Mg3 and (Bi)1 (Bi,Va)aMg6 respectively based on their structure features.A set of self-consistent thermodynamic parameters of the Bi-Mg system was obtained and the experimental thermodynamic and phase equilibrium data were well reproduced by the optimized thermodynamic data.

  17. Directional Solidification of a Binary Alloy into a Cellular Convective Flow: Localized Morphologies

    Science.gov (United States)

    Chen, Y.- J.; Davis, S. H.

    1999-01-01

    A steady, two dimensional cellular convection modifies the morphological instability of a binary alloy that undergoes directional solidification. When the convection wavelength is far longer than that of the morphological cells, the behavior of the moving front is described by a slow, spatial-temporal dynamics obtained through a multiple-scale analysis. The resulting system has a "parametric-excitation" structure in space, with complex parameters characterizing the interactions between flow, solute diffusion, and rejection. The convection stabilizes two dimensional disturbances oriented with the flow, but destabilizes three dimensional disturbances in general. When the flow is weak, the morphological instability behaves incommensurably to the flow wavelength, but becomes quantized and forced to fit into the flow-box as the flow gets stronger. At large flow magnitudes the instability is localized, confined in narrow envelopes with cells traveling with the flow. In this case the solutions are discrete eigenstates in an unbounded space. Their stability boundary and asymptotics are obtained by the WKB analysis.

  18. Thermodynamic assessment of the Ni-Sb binary system

    Institute of Scientific and Technical Information of China (English)

    CAO Zhanmin; TAKADU Yoshikazu; OHNUMA Ikuo; KAINUMA Ryosuke; ZHU Hongmin; ISHIDA Kiyohito

    2008-01-01

    The Ni-Sb binary alloy system was thermodynamically assessed using CALPHAD approach in this article.Excess Gibbs energies of solution phases,liquid and fcc phases,were formulated using the Redlich-Kister expression.The intermediate phases were modeled by the sublattice model with (Ni,Va)0.5(Ni,Sb)0.25(Ni)0.25 for Ni3Sb_HT phase and (Ni,Va)0.3333(Sb)0.3333(Ni,Va)0.3333 for NiSb phase.The other phases including Ni3Sb,Ni7Sb3,and NiSb2 were treated as stoichiometric compound owing to their narrow composition ranges.Based on the reported thermodynamic properties and phase diagram data,the thermodynamic parameters of these phases were optimized,and the obtained values can reproduce the available experimental data well.

  19. Stellivore extraterrestrials? Binary stars as living systems

    Science.gov (United States)

    Vidal, Clément

    2016-11-01

    We lack signs of extraterrestrial intelligence (ETI) despite decades of observation in the whole electromagnetic spectrum. Could evidence be buried in existing data? To recognize ETI, we first propose criteria discerning life from non-life based on thermodynamics and living systems theory. Then we extrapolate civilizational development to both external and internal growth. Taken together, these two trends lead to an argument that some existing binary stars might actually be ETI. Since these hypothetical beings feed actively on stars, we call them "stellivores". I present an independent thermodynamic argument for their existence, with a metabolic interpretation of interacting binary stars. The jury is still out, but the hypothesis is empirically testable with existing astrophysical data.

  20. Brown Dwarf Binaries from Disintegrating Triple Systems

    CERN Document Server

    Reipurth, Bo

    2015-01-01

    We have carried out 200,000 N-body simulations of three identical stellar embryos with masses from a Chabrier IMF and embedded in a molecular core. The bodies are initially non-hierarchical and undergo chaotic motions, while accreting using Bondi-Hoyle accretion. The coupling of dynamics and accretion often leads to one or two dominant bodies controlling the center of the cloud core, while banishing the other(s) to the lower-density outskirts, leading to stunted growth. Eventually each system transforms either to a bound hierarchical configuration or breaks apart into separate single and binary components. The orbital motion is followed for 100 Myr. To illustrate the simulations we introduce the 'triple diagnostic diagram', which plots two dimensionless numbers against each other, representing the binary mass ratio and the mass ratio of the third body to the total system mass. Numerous freefloating BD binaries are formed in these simulations. The separation distribution function is in good correspondence with...

  1. Relationship between the types of binary alloy phase diagrams of VIII and IB group elements and the Mendeleev numbers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The relationship between the types of binary alloy phase diagrams of Vlll and IB group elements and the Men deleev numbers was discussed for the first time using the Vlll and IB group elements as solvent metals (A) and the other elements as solute metals (B), basesd on their alloy phase diagram types. The Mendeleev numbers of the solvent metals and the solute metals were expressed as Ma and MB, respectively. A two-dimension map of MdMB was drawn. It is indicated that there is an oblique line in the map, which divides the binary alloy phase diagram types of solvent metals into two symmetry parts, the phase diagram types of the other elements with solvent metals located at the above or down of the line respectively, while on the line, AM= 0. The phase diagrams between the solvent metals basically are simple systems, mainly belong to the types of continues solid solution and the peritectic (about 40% for each type). The solvent metals can be divided into three groups: Co, Ir, Rh, Ni, Pt, and Pd as the first group; Ag, Au, and Cu as the second group;and Fe, Os, and Ru as the third group. The characteristics of the phase diagrams formed between the elements in each group were discussed. About 80% phase diagrams belong to complex systems and less than 20% belong to the simple systems. The regular variation of the chemical scale, the metallic radii of the atoms, the number of valence electrons, and the first ionization energy with the Mendeleev numbers and the crystal structure were introduced as well.

  2. Preparation and electrochemical properties of binary SixSb immiscible alloy for lithium ion batteries

    International Nuclear Information System (INIS)

    Highlights: • The SixSb immiscible alloy was synthesized by chemical reduction-mechanical alloying methods. • The Si0.8Sb anodes exhibit the best electrochemical and cycle performances. • The volume expansion can be whittled by making lithiation products buffering matrices for each other. • The lithiation and delithiation reaction mechanism are investigated. - Abstract: The novel binary SixSb immiscible alloy was synthesized using chemical reduction-mechanical alloying methods and first investigated as possible anodes for lithium ion batteries. The microstructures, morphologies and electrochemical properties were investigated utilizing X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), constant-current charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Results showed that tiny Si particles were dispersed homogeneously in Sb active matrix. Cyclic voltammetry results indicated that the Li+-transport rates were significantly enhanced in the SixSb immiscible alloy. Results also showed that the Si0.8Sb exhibited the best cyclability with a reversible capacity of 596.4 mAh g−1 after 50 cycles. The cyclability can be improved by restricting either the upper or lower cutoff voltage, which can control the lithiation/delithiation degree and prevented the powdering and shredding of the active materials after Li+ trapped into electrode materials

  3. Effects of Surface Structure and Chemical Composition of Binary Ti Alloys on Cell Differentiation

    Directory of Open Access Journals (Sweden)

    Ok-Sung Han

    2016-07-01

    Full Text Available Binary Ti alloys containing Fe, Mo, V and Zr were micro-arc oxidized and hydrothermally treated to obtain micro- and nano-porous layers. This study aimed to investigate cell differentiation on micro and micro/nanoporous oxide layers of Ti alloys. The properties of the porous layer formed on Ti alloys were characterized by X-ray diffraction pattern, microstructural and elemental analyses and inductively coupled plasma mass spectrometry (ICP-MS method. The MTT assay, total protein production and alkaline phosphatase (ALPase activity were evaluated using human osteoblast-like cells (MG-63. Microporous structures of micro-arc oxidized Ti alloys were changed to micro/nanoporous surfaces after hydrothermal treatment. Micro/nanoporous surfaces consisted of acicular TiO2 nanoparticles and micron-sized hydroxyapatite particles. From ICP and MTT tests, the Mo and V ions released from porous oxide layers were positive for cell viability, while the released Fe ions were negative for cell viability. Although the micro/nanoporous surfaces led to a lower total protein content than the polished and microporous Ti surfaces after cell incubation for 7 days, they caused higher ALPase activities after 7 days and 14 days of incubation except for V-containing microporous surfaces. The micro/nanoporous surfaces of Ti alloys were more efficient in inducing MG-63 cell differentiation.

  4. Microstructure and mechanical behavior of metal injection molded Ti-Nb binary alloys as biomedical material.

    Science.gov (United States)

    Zhao, Dapeng; Chang, Keke; Ebel, Thomas; Qian, Ma; Willumeit, Regine; Yan, Ming; Pyczak, Florian

    2013-12-01

    The application of titanium (Ti) based biomedical materials which are widely used at present, such as commercially pure titanium (CP-Ti) and Ti-6Al-4V, are limited by the mismatch of Young's modulus between the implant and the bones, the high costs of products, and the difficulty of producing complex shapes of materials by conventional methods. Niobium (Nb) is a non-toxic element with strong β stabilizing effect in Ti alloys, which makes Ti-Nb based alloys attractive for implant application. Metal injection molding (MIM) is a cost-efficient near-net shape process. Thus, it attracts growing interest for the processing of Ti and Ti alloys as biomaterial. In this investigation, metal injection molding was applied to the fabrication of a series of Ti-Nb binary alloys with niobium content ranging from 10wt% to 22wt%, and CP-Ti for comparison. Specimens were characterized by melt extraction, optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Titanium carbide formation was observed in all the as-sintered Ti-Nb binary alloys but not in the as-sintered CP-Ti. Selected area electron diffraction (SAED) patterns revealed that the carbides are Ti2C. It was found that with increasing niobium content from 0% to 22%, the porosity increased from about 1.6% to 5.8%, and the carbide area fraction increased from 0% to about 1.8% in the as-sintered samples. The effects of niobium content, porosity and titanium carbides on mechanical properties have been discussed. The as-sintered Ti-Nb specimens exhibited an excellent combination of high tensile strength and low Young's modulus, but relatively low ductility.

  5. Microstructure and mechanical behavior of metal injection molded Ti-Nb binary alloys as biomedical material.

    Science.gov (United States)

    Zhao, Dapeng; Chang, Keke; Ebel, Thomas; Qian, Ma; Willumeit, Regine; Yan, Ming; Pyczak, Florian

    2013-12-01

    The application of titanium (Ti) based biomedical materials which are widely used at present, such as commercially pure titanium (CP-Ti) and Ti-6Al-4V, are limited by the mismatch of Young's modulus between the implant and the bones, the high costs of products, and the difficulty of producing complex shapes of materials by conventional methods. Niobium (Nb) is a non-toxic element with strong β stabilizing effect in Ti alloys, which makes Ti-Nb based alloys attractive for implant application. Metal injection molding (MIM) is a cost-efficient near-net shape process. Thus, it attracts growing interest for the processing of Ti and Ti alloys as biomaterial. In this investigation, metal injection molding was applied to the fabrication of a series of Ti-Nb binary alloys with niobium content ranging from 10wt% to 22wt%, and CP-Ti for comparison. Specimens were characterized by melt extraction, optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Titanium carbide formation was observed in all the as-sintered Ti-Nb binary alloys but not in the as-sintered CP-Ti. Selected area electron diffraction (SAED) patterns revealed that the carbides are Ti2C. It was found that with increasing niobium content from 0% to 22%, the porosity increased from about 1.6% to 5.8%, and the carbide area fraction increased from 0% to about 1.8% in the as-sintered samples. The effects of niobium content, porosity and titanium carbides on mechanical properties have been discussed. The as-sintered Ti-Nb specimens exhibited an excellent combination of high tensile strength and low Young's modulus, but relatively low ductility. PMID:23994942

  6. Modelling of binary alloy (Al–Mg) anode evaporation in arc welding

    International Nuclear Information System (INIS)

    A simple analytical model of binary alloy anode evaporation in gas–tungsten arc and gas–metal arc welding is proposed. The model comprises the model of evaporation in convective and diffusive regimes, model of anode processes and allows one to calculate basic physical properties of multicomponent arc plasma near the anode surface as functions of the anode surface temperature, anode chemical composition, electron temperature and electric current density at the anode surface. Evaporation of binary Al–Mg alloys with different magnesium mass fraction into argon plasma is considered on the basis of the proposed model. The dependences of the alloy boiling temperature on the magnesium mass fraction and electron temperature are presented. Several physical parameters, which are important from the technological point of view (magnesium mass flux, heat loss due to evaporation, anode potential drop, anode heat flux), are calculated for a wide range of anode surface temperature and different values of the magnesium mass fraction. In addition, the influence of heat loss due to evaporation on the total heat flux coming to the anode surface is demonstrated. (paper)

  7. New spectroscopic binary companions of giant stars and updated metallicity distribution for binary systems

    CERN Document Server

    Bluhm, P; Vanzi, L; Soto, M G; Vos, J; Wittenmyer, R A; Olivares, F; Drass, H; Mennickent, R E; Vuckovic, M; Rojo, P; Melo, C H F

    2016-01-01

    We report the discovery of 24 spectroscopic binary companions to giant stars. We fully constrain the orbital solution for 6 of these systems. We cannot unambiguously derive the orbital elements for the remaining stars because the phase coverage is incomplete. Of these stars, 6 present radial velocity trends that are compatible with long-period brown dwarf companions.The orbital solutions of the 24 binary systems indicate that these giant binary systems have a wide range in orbital periods, eccentricities, and companion masses. For the binaries with restricted orbital solutions, we find a range of orbital periods of between $\\sim$ 97-1600 days and eccentricities of between $\\sim$ 0.1-0.4. In addition, we studied the metallicity distribution of single and binary giant stars. We computed the metallicity of a total of 395 evolved stars, 59 of wich are in binary systems. We find a flat distribution for these binary stars and therefore conclude that stellar binary systems, and potentially brown dwarfs, have a diffe...

  8. A Compact Supermassive Binary Black Hole System

    CERN Document Server

    Rodríguez, C; Zavala, R T; Peck, A B; Pollack, L K; Romani, R W

    2006-01-01

    We report on the discovery of a supermassive binary black hole system in the radio galaxy 0402+379, with a projected separation between the two black holes of just 7.3 pc. This is the closest black hole pair yet found by more than two orders of magnitude. These results are based upon recent multi-frequency observations using the Very Long Baseline Array (VLBA) which reveal two compact, variable, flat-spectrum, active nuclei within the elliptical host galaxy of 0402+379. Multi-epoch observations from the VLBA also provide constraints on the total mass and dynamics of the system. Low spectral resolution spectroscopy using the Hobby-Eberly Telescope indicates two velocity systems with a combined mass of the two black holes of ~1.5 x 10^8 solar masses. The two nuclei appear stationary while the jets emanating from the weaker of the two nuclei appear to move out and terminate in bright hot spots. The discovery of this system has implications for the number of close binary black holes that might be sources of gravi...

  9. RS CV sub n binary systems

    Science.gov (United States)

    Linsky, J. L.

    1984-01-01

    An attempt is made to place in context the vast amount of data obtained as a result of X-ray, ultraviolet, optical, and microwave observations of RS CVn and similar spectroscopic binary systems. Emphasis is on the RS CVn systems and their long period analogs. The following questions are considered: (1) are the original defining characteristics still valid and still adequate? (2) what is the evidence for discrete active regions? (3) have any meaningful physical properties for the atmospheres of RS CVn systems been derived? (4) what do the flare observations tell about magnetic fields in RS CVn systems? (5) is there evidence for systematic trends in RS CVn systems with spectral type?

  10. GPU phase-field lattice Boltzmann simulations of growth and motion of a binary alloy dendrite

    Science.gov (United States)

    Takaki, T.; Rojas, R.; Ohno, M.; Shimokawabe, T.; Aoki, T.

    2015-06-01

    A GPU code has been developed for a phase-field lattice Boltzmann (PFLB) method, which can simulate the dendritic growth with motion of solids in a dilute binary alloy melt. The GPU accelerated PFLB method has been implemented using CUDA C. The equiaxed dendritic growth in a shear flow and settling condition have been simulated by the developed GPU code. It has been confirmed that the PFLB simulations were efficiently accelerated by introducing the GPU computation. The characteristic dendrite morphologies which depend on the melt flow and the motion of the dendrite could also be confirmed by the simulations.

  11. Domain of oscillatory growth in directional solidification of dilute binary alloys.

    Science.gov (United States)

    Babushkina, Evgenia; Bessonov, Nicholas M; Korzhenevskii, Alexander L; Bausch, Richard; Schmitz, Rudi

    2013-04-01

    The oscillatory growth of a dilute binary alloy has recently been described by a nonlinear oscillator equation that applies to small temperature gradients and large growth velocities in the setup of directional solidification. Based on a one-dimensional stability analysis of stationary solutions of this equation, we explore in the present paper the complete region where the solidification front propagates in an oscillatory way. The boundary of this region is calculated exactly, and the nature of the oscillations is evaluated numerically in several segments of the region.

  12. A New Thermodynamic Calculation Method for Binary Alloys Part II: Exploring the Correction Factor Function

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new method of revising activity values has been derived based on the so called correction factor function for binary alloys with a large difference between two components. The correction factor is a function of physical properties formed by the difference of two components. Its absolute value increases with the enhancement of the difference in the character of components. It can be either positive or negative and the rules for selecting the sign of correction factor have been analyzed. Results are in good agreement with the experimental values.

  13. Collective Modes and Elastic Constants of Liquid Al83Cu17 Binary Alloy

    Institute of Scientific and Technical Information of China (English)

    B.Y.Thakore; S.G.Khambholja; P.H.Suthar; N.K.Bhatt; A.R.Jani

    2010-01-01

    @@ The collective dynamics(longitudinal and transverse phonon modes)are studied for aluminum-copper(Al-Cu)binary alloy in terms of the eigen-frequencies of the localized collective excitations.The model pseudopotential formalism is employed using a self-consistent phonon scheme by involving multiple scattering and phonon eigenfrequencies.These frequencies are expressed in terms of many-body correlation functions of atoms as well as of interatomic potential.The important ingredients in the present study are the pair-potential and pair-correlation functions.

  14. Preparation of ferromagnetic binary alloy fine fibers byorganic gel-thermal reduction process

    Institute of Scientific and Technical Information of China (English)

    SHEN Xiang-qian; CAO Kai; ZHOU Jian-xin

    2006-01-01

    Ferromagnetic metal fibers with a high aspect ratio (length/diameter) are attractive for use as high performance electromagnetic interference shielding materials. Ferromagnetic binary alloy fine fibers of iron-nickel, iron-cobalt and cobalt-nickel were prepared by the organic gel-thermal reduction process from the raw materials of critic acid and metal salts. These alloy fibers synthesized were featured with a diameter of about 1 μm and a length as long as 1 m. The structure, thermal decomposition process and morphologies of the gel precursors and fibers derived from thermal reduction of the gel precursors were characterized by FTIR, XRD, TG/DSC and SEM. The gel spinnability largely depends on the molecular structure of metal- carboxylates formed during the gel formation. The gel consisting of linear-type structural molecules shows good spinnability.

  15. Gadolinium solubility and precipitate identification in Mg-Gd binary alloy

    Institute of Scientific and Technical Information of China (English)

    PENG Qiuming; MA Ning; LI Hui

    2012-01-01

    Gadolinium (Gd) solubility in magnesium (Mg) matrix and precipitate composition in Mg-Gd binary alloys were investigated.The alloys containing different Gd contents (10 wt.%-35 wt.%) were employed to identify Gd solubility after annealing at different temperatures.It was confirmed that the maximum Gd solubility was 22.8 wt.% at 550 ℃ based on the regression analysis method.Mg5+xGd (0<x<2) and Mg3Gd precipitates coexisted in all investigated alloys owing to the strong component segregation during solidification.The fiaction of Mg5+xGd (0<x<2) was decreased with the increment of annealing temperature and time.In contrast,Mg3Gd precipitate could not be eliminated even when being annealed at 550 ℃.This thermal stable precipitate played a significant role in mechanical properties.Therefore,it is very necessary to consider the effect of Mg3Gd precipitate on properties of Mg-Gd based alloys in future.

  16. Influence of cooling rate on microstructure formation during rapid solidification of binary TiAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kenel, C., E-mail: Christoph.Kenel@empa.ch; Leinenbach, C.

    2015-07-15

    Highlights: • Rapid solidification studies with varying cooling rates were realized for Ti–Al. • Experiments were combined with finite element simulations of heat transfer. • The resulting microstructure of Ti–Al alloys is strongly dependent on the Al content. • The microstructure and phase transformation behavior can be predicted. • The method allows alloy development for processes involving rapid solidification. - Abstract: Titanium aluminides as structural intermetallics are possible candidates for a potential weight reduction and increased performance of high temperature components. A method for the characterization of the microstructure formation in rapidly solidified alloys was developed and applied for binary Ti–(44–48)Al (at.%). The results show a strong dependency of the microstructure on the Al content at cooling rates between 6 ⋅ 10{sup 2} and 1.5 ⋅ 10{sup 4} K s{sup −1}. The formation of α → α{sub 2} ordering, lamellar α{sub 2} + γ colonies and interdendritic TiAl γ-phase were observed, depending on the Al amount. Based on thermodynamic calculations the observed microstructure can be explained using the CALPHAD approach taking into account the non-equilibrium conditions. The presented method provides a useful tool for alloy development for processing techniques involving rapid solidification with varying cooling rates.

  17. Ingredient Losses during Melting Binary Ni-Ti Shape Memory Alloys

    Institute of Scientific and Technical Information of China (English)

    S.K. Sadrnezhaad; S. Badakhshan Raz

    2005-01-01

    Losses of the alloying elements during vacuum induction melting of the binary NiTi alloys were evaluated by visual observation and chemical analysis of the NiTi melted specimens and the scalp formed on the internal surface of the crucible. The results indicated that the major sources of the losses were (a) evaporation of the metals, (b) formation of the NiTi scalp and (c) the sprinkling drops splashed out of the melt due to the exothermic reactions occurring between Ni and Ti to form the NiTi parent phase. Quantitative evaluations were made for the metallic losses by holding the molten alloy for 0.5, 3, 5, 10 and 15 min at around 100℃ above the melting point inside the crucible.Chemical analysis showed that there existed an optimum holding time of 3 min during which the alloying elements were only dropped to a predictable limit. Microstructure, chemical composition, shape memory and mechanical properties of the cast metal ingots were determined to indicate the appropriate achievements with the specified 3 min optimum holding time.

  18. Numerical simulation of recalescence of 3-dimensional isothermal solidification for binary alloy using phase-field approach

    Institute of Scientific and Technical Information of China (English)

    ZHU Chang-sheng; XIAO Rong-zhen; WANG Zhi-ping; FENG Li

    2009-01-01

    A accelerated arithmetic algorithm of the dynamic computing regions was designed, and 3-dimensional numerical simulation of isothermal solidification for a binary alloy was implemented. The dendritic growth and the recalescence of Ni-Cu binary alloy during the solidification at different cooling rates were investigated. The effects of cooling rate on dendritic patterns and microsegregation patterns were studied. The computed results indicate that, with the increment of the cooling rate, the dendritic growth velocity increases, both the main branch and side-branches become slender, the secondary dendrite arm spacing becomes smaller, the inadequate solute diffusion in solid aggravates, and the severity of microsegregation ahead of interface aggravates. At a higher cooling rate, the binary alloy presents recalescence; while the cooling rate is small, no recalescence occurs.

  19. OJ 287 binary black hole system

    CERN Document Server

    Valtonen, Mauri

    2011-01-01

    The light curve of the quasar OJ 287 extends from 1891 up today without major gaps. Here we summarize the results of the 2005 - 2010 observing campaign. The main results are the following: (1) The 2005 October optical outburst came at the expected time, thus confirming the general relativistic precession in the binary black hole system. This result disproved the model of a single black hole system with accretion disk oscillations, as well as several toy models of binaries without relativistic precession. In the latter models the main outburst would have been a year later. (2) The nature of the radiation of the 2005 October outburst was expected to be bremsstrahlung from hot gas at the temperature of $3\\times 10^{5}$ $^{\\circ}$K. This was confirmed by combined ground based and ultraviolet observations using the XMM-Newton X-ray telescope. (3) A secondary outburst of the same nature was expected at 2007 September 13. Within the accuracy of observations (about 6 hours), it started at the correct time. Thus the p...

  20. NONLINEAR TIDES IN CLOSE BINARY SYSTEMS

    International Nuclear Information System (INIS)

    We study the excitation and damping of tides in close binary systems, accounting for the leading-order nonlinear corrections to linear tidal theory. These nonlinear corrections include two distinct physical effects: three-mode nonlinear interactions, i.e., the redistribution of energy among stellar modes of oscillation, and nonlinear excitation of stellar normal modes by the time-varying gravitational potential of the companion. This paper, the first in a series, presents the formalism for studying nonlinear tides and studies the nonlinear stability of the linear tidal flow. Although the formalism we present is applicable to binaries containing stars, planets, and/or compact objects, we focus on non-rotating solar-type stars with stellar or planetary companions. Our primary results include the following: (1) The linear tidal solution almost universally used in studies of binary evolution is unstable over much of the parameter space in which it is employed. More specifically, resonantly excited internal gravity waves in solar-type stars are nonlinearly unstable to parametric resonance for companion masses M' ∼> 10-100 M⊕ at orbital periods P ≈ 1-10 days. The nearly static 'equilibrium' tidal distortion is, however, stable to parametric resonance except for solar binaries with P ∼3[P/10 days] for a solar-type star) and drives them as a single coherent unit with growth rates that are a factor of ≈N faster than the standard three-wave parametric instability. These are local instabilities viewed through the lens of global analysis; the coherent global growth rate follows local rates in the regions where the shear is strongest. In solar-type stars, the dynamical tide is unstable to this collective version of the parametric instability for even sub-Jupiter companion masses with P ∼< a month. (4) Independent of the parametric instability, the dynamical and equilibrium tides excite a wide range of stellar p-modes and g-modes by nonlinear inhomogeneous forcing

  1. Nonlinear Tides in Close Binary Systems

    Science.gov (United States)

    Weinberg, Nevin N.; Arras, Phil; Quataert, Eliot; Burkart, Josh

    2012-06-01

    We study the excitation and damping of tides in close binary systems, accounting for the leading-order nonlinear corrections to linear tidal theory. These nonlinear corrections include two distinct physical effects: three-mode nonlinear interactions, i.e., the redistribution of energy among stellar modes of oscillation, and nonlinear excitation of stellar normal modes by the time-varying gravitational potential of the companion. This paper, the first in a series, presents the formalism for studying nonlinear tides and studies the nonlinear stability of the linear tidal flow. Although the formalism we present is applicable to binaries containing stars, planets, and/or compact objects, we focus on non-rotating solar-type stars with stellar or planetary companions. Our primary results include the following: (1) The linear tidal solution almost universally used in studies of binary evolution is unstable over much of the parameter space in which it is employed. More specifically, resonantly excited internal gravity waves in solar-type stars are nonlinearly unstable to parametric resonance for companion masses M' >~ 10-100 M ⊕ at orbital periods P ≈ 1-10 days. The nearly static "equilibrium" tidal distortion is, however, stable to parametric resonance except for solar binaries with P companion masses larger than a few Jupiter masses, the dynamical tide causes short length scale waves to grow so rapidly that they must be treated as traveling waves, rather than standing waves. (3) We show that the global three-wave treatment of parametric instability typically used in the astrophysics literature does not yield the fastest-growing daughter modes or instability threshold in many cases. We find a form of parametric instability in which a single parent wave excites a very large number of daughter waves (N ≈ 103[P/10 days] for a solar-type star) and drives them as a single coherent unit with growth rates that are a factor of ≈N faster than the standard three

  2. Spectral modelling of massive binary systems

    CERN Document Server

    Palate, Matthieu; Koenigsberger, Gloria; Moreno, Edmundo

    2013-01-01

    Aims: We simulate the spectra of massive binaries at different phases of the orbital cycle, accounting for the gravitational influence of the companion star on the shape and physical properties of the stellar surface. Methods: We used the Roche potential modified to account for radiation pressure to compute the stellar surface of close circular systems and we used the TIDES code for surface computation of eccentric systems. In both cases, we accounted for gravity darkening and mutual heating generated by irradiation to compute the surface temperature. We then interpolated NLTE plane-parallel atmosphere model spectra in a grid to obtain the local spectrum at each surface point. We finally summed all contributions, accounting for the Doppler shift, limb-darkening, and visibility to obtain the total synthetic spectrum. We computed different orbital phases and sets of physical and orbital parameters. Results: Our models predict line strength variations through the orbital cycle, but fail to completely reproduce t...

  3. Static and Vibrational Properties of Equiatomic Cesium-Alkali Binary Alloys

    Directory of Open Access Journals (Sweden)

    Aditya M. Vora

    2012-07-01

    Full Text Available The computations of the static and vibrational properties of four equiatomic Cs-based binary alloys viz. Cs0.5Li0.5, Cs0.5Na0.5, Cs0.5K0.5 and Cs0.5Rb0.5 to second order in local model potential is discussed in terms of real-space sum of Born von Karman central force constants. The local field correlation functions due to Hartree (H, Ichimaru-Utsumi (IU and Sarkar et al. (S are used to investigate influence of the screening effects on the aforesaid properties. Results for the lattice constants, i.e. С11, С12, С44, С12 – С44, С12 / С44, and bulk modulus B obtained using the H-local field correction function, have higher values in comparison with the results obtained for the same properties using IU and S local field correction functions. The results for the Shear modulus (C, deviation from Cauchy’s relation, Poisson’s ratio , Young modulus Y, propagation velocity of elastic waves, phonon dispersion curves and degree of anisotropy A are highly appreciable for the four equiatomic Cs-based binary alloys.

  4. Plasma electrolytic oxidation coating of synthetic Al-Mg binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tarakci, Mehmet, E-mail: mtarakci@gyte.edu.tr

    2011-12-15

    The binary Al-Mg synthetic alloys were prepared in a vacuum/atmosphere controlled furnace with the addition of 0.5, 1, 2, 4, 7, and 15 wt.% pure Mg into pure aluminum as substrate material. The surfaces of the Al-Mg alloys and pure aluminum were coated for 120 min by plasma electrolytic oxidation in the same electrolyte of 12 g/L sodium silicate and 2 g/L KOH in distilled water. The coating was characterized by X-ray diffraction, scanning electron microscopy, profilometry and Vickers microhardness measurements. There regions of loose outer layer, dense inner layer with precipitate like particles of {alpha}-Al{sub 2}O{sub 3} and a thin transition layer were identified for the coated samples. The coating thickness increases from 85 to 150 {mu}m with Mg contents in the alloys. The surface morphology becomes more porous and consequently surface roughness tends to increase with plasma electrolytic oxidation treatment and further with Mg content. The increase in magnesium content reduces the formation of {alpha}-Al{sub 2}O{sub 3} and crystalline mullite phases in the coating and decreases microhardness of coating. The Mg concentration is constant throughout the other loose and dense regions of coating though it gradually decreases in the thin inner region. - Research Highlights: Black-Right-Pointing-Pointer The average thickness of PEO coating of Al-Mg alloys increases with Mg content. Black-Right-Pointing-Pointer The addition of Mg reduces and prevents the formation of {alpha}-Al{sub 2}O{sub 3} and mullite. Black-Right-Pointing-Pointer The surface roughness increases with Mg content in the Al-Mg alloys. Black-Right-Pointing-Pointer The hardness values of the coating decreases with the Mg amount in the substrate. Black-Right-Pointing-Pointer The Mg concentration is constant throughout the main regions of coating.

  5. Milankovitch Cycles of Terrestrial Planets in Binary Star Systems

    CERN Document Server

    Forgan, Duncan H

    2016-01-01

    The habitability of planets in binary star systems depends not only on the radiation environment created by the two stars, but also on the perturbations to planetary orbits and rotation produced by the gravitational field of the binary and neighbouring planets. Habitable planets in binaries may therefore experience significant perturbations in orbit and spin. The direct effects of orbital resonances and secular evolution on the climate of binary planets remain largely unconsidered. We present latitudinal energy balance modelling of exoplanet climates with direct coupling to an N Body integrator and an obliquity evolution model. This allows us to simultaneously investigate the thermal and dynamical evolution of planets orbiting binary stars, and discover gravito-climatic oscillations on dynamical and secular timescales. We investigate the Kepler-47 and Alpha Centauri systems as archetypes of P and S type binary systems respectively. In the first case, Earthlike planets would experience rapid Milankovitch cycle...

  6. Asteroid Systems: Binaries, Triples, and Pairs

    CERN Document Server

    Margot, Jean-Luc; Taylor, Patrick; Carry, Benoît; Jacobson, Seth

    2015-01-01

    In the past decade, the number of known binary near-Earth asteroids has more than quadrupled and the number of known large main belt asteroids with satellites has doubled. Half a dozen triple asteroids have been discovered, and the previously unrecognized populations of asteroid pairs and small main belt binaries have been identified. The current observational evidence confirms that small (20 km) binaries with small satellites are most likely created during large collisions.

  7. Quantum chemical analysis of binary and ternary ferromagnetic alloys; Quantenchemische Untersuchungen binaerer und ternaerer ferromagnetischer Legierungen

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Yasemin Erika Charlotte

    2007-02-23

    In this work the electronic structures, densities of states, chemical bonding, magnetic exchange Parameters and Curie temperatures of binary and ternary ferromagnetic alloys are analyzed. The electronic structure of ferromagnetic MnAl has been calculated using density-functional techniques (TB-LMTO-ASA, FPLAPW) and quantum chemically analyzed by means of the crystal orbital Hamilton population analysis. The crystal structure of the ferromagnetic tetragonal MnAl may be understood to originate from the structure of nonmagnetic cubic MnAl with a CsCl motif through a two-step process. While the nonmagnetic cubic structure is stable against a structural deformation, antibonding Mn-Mn interactions at the Fermi level lead to spin polarization and the onset of magnetism, i.e., a symmetry reduction taking place solely in the electronic degrees of freedom, by that emptying antibonding Mn-Mn states. Residual antibonding Al--Al states can only be removed by a subsequent, energetically smaller structural deformation towards the tetragonal system. As a final result, homonuclear bonding is strengthened and heteronuclear bonding is weakened. Corresponding DFT calculations of the electronic structure as well as the calculation of the chemical bonding and the magnetic exchange interactions have been performed on the basis of LDA and GGA for a series of ferromagnetic full Heusler alloys of general formula Co2MnZ (Z=Ga,Si,Ge,Sn), Rh2MnZ (Z=Ge,Sn,Pb), Ni2MnZ (Z=Ga,In,Sn), Pd2MnZ (Z=Sn,Sb) and Cu2MnZ (Z=Al,In,Sn). The connection between the electronic spectra and the magnetic interactions have been studied. Correlations between the chemical bondings in Heusler alloys derived from COHP analysis and magnetic phenomena are obvious, and different mechanisms leading to spin polarization and ferromagnetism are derived. The band dependence of the exchange parameters, their dependence on volume and valence electron concentration have been thoroughly analyzed within the Green function technique

  8. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. I. S-TYPE BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Kaltenegger, Lisa [MPIA, Koenigstuhl 17, D-69117 Heidelberg (Germany); Haghighipour, Nader, E-mail: kaltenegger@mpia.de [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States)

    2013-11-10

    We have developed a comprehensive methodology for calculating the boundaries of the habitable zone (HZ) of planet-hosting S-type binary star systems. Our approach is general and takes into account the contribution of both stars to the location and extent of the binary HZ with different stellar spectral types. We have studied how the binary eccentricity and stellar energy distribution affect the extent of the HZ. Results indicate that in binaries where the combination of mass-ratio and orbital eccentricity allows planet formation around a star of the system to proceed successfully, the effect of a less luminous secondary on the location of the primary's HZ is generally negligible. However, when the secondary is more luminous, it can influence the extent of the HZ. We present the details of the derivations of our methodology and discuss its application to the binary HZ around the primary and secondary main-sequence stars of an FF, MM, and FM binary, as well as two known planet-hosting binaries α Cen AB and HD 196886.

  9. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. I. S-TYPE BINARIES

    International Nuclear Information System (INIS)

    We have developed a comprehensive methodology for calculating the boundaries of the habitable zone (HZ) of planet-hosting S-type binary star systems. Our approach is general and takes into account the contribution of both stars to the location and extent of the binary HZ with different stellar spectral types. We have studied how the binary eccentricity and stellar energy distribution affect the extent of the HZ. Results indicate that in binaries where the combination of mass-ratio and orbital eccentricity allows planet formation around a star of the system to proceed successfully, the effect of a less luminous secondary on the location of the primary's HZ is generally negligible. However, when the secondary is more luminous, it can influence the extent of the HZ. We present the details of the derivations of our methodology and discuss its application to the binary HZ around the primary and secondary main-sequence stars of an FF, MM, and FM binary, as well as two known planet-hosting binaries α Cen AB and HD 196886

  10. Structure and properties of nitrided binary Fe-Al, Fe-V, Fe-Ti alloys

    International Nuclear Information System (INIS)

    The structure of binary alloys Fe-Al (up to 6.85% Al), Fe-V (up to 1.86% V), and Fe-Ti (up to 1.26% Ti) nitrated for 1 hr at 500 deg C has been investigated. The forming of the nitrous phases in the diffusion layers corresponds to the Fe-N diagram. The surface layer consists of epsilon -/nitride of Fe3N, then follows the γ'-phase, and further a wide region of a nitrous α-solid solution. Separate crystals of Al2O3 have been found on the surface of nitrated Fe-Al alloys. The ferrite hardness is increased most efficiently by titanium, less noticeably by vanadium, and only slightly by aluminium. It has been established that the diffusion sublayer of the Fe-Ti and Fe-V alloys contains, in addition to the segregations of the excess γ'-phase, another nitride phase Fe16N2, which is isomorphous with the matrix. The matrix reflexes indicate the effect of diffusion scattering in the form of rods, which points to the formation of clusters or Guinier-Preston zones coherent or partly coherent with the matrix

  11. Ultra-High Strength and Ductile Lamellar-Structured Powder Metallurgy Binary Ti-Ta Alloys

    Science.gov (United States)

    Liu, Yong; Xu, Shenghang; Wang, Xin; Li, Kaiyang; Liu, Bin; Wu, Hong; Tang, Huiping

    2016-03-01

    Ultra-high strength and ductile powder metallurgy (PM) binary Ti-20at.%Ta alloy has been fabricated via sintering from elemental Ti and Ta powders and subsequent hot swaging and annealing. The microstructural evolution and mechanical properties in each stage were evaluated. Results show that inhomogeneous microstructures with Ti-rich and Ta-rich areas formed in the as-sintered Ti-Ta alloys due to limited diffusion of Ta. In addition, Kirkendall porosity was observed as a result of the insufficient diffusion of Ta. Annealing at 1000°C for up to 24 h failed to eliminate the pores. Hot swaging eliminated the residual sintering porosity and created a lamellar microstructure, consisting of aligned Ta-enriched and Ti-enriched phases. The hot-swaged and annealed PM Ti-20Ta alloy achieved an ultimate tensile strength of 1600 MPa and tensile elongation of more than 25%, due to its unique lamellar microstructure including the high toughness of Ta-enriched phases, the formation of α phase in the β matrix and the refined lamellae.

  12. Magnetic Interaction in Ultra-compact Binary Systems

    CERN Document Server

    Wu, Kinwah

    2009-01-01

    This article reviews the current works on ultra-compact double-degenerate binaries in the presence of magnetic interaction, in particular, unipolar induction. The orbital dynamics and evolution of compact white-dwarf pairs are discussed in detail. Models and predictions of electron cyclotron masers from unipolar-inductor compact binaries and unipolar-inductor white-dwarf planetary systems are presented. Einstein-Laub effects in compact binaries are briefly discussed.

  13. Magnetic interaction in ultra-compact binary systems

    Institute of Scientific and Technical Information of China (English)

    Kinwah WU

    2009-01-01

    This article reviews the current works on ultra-compact double-degenerate binaries in the presence of magnetic interaction, in particular, unipolar induction. The orbital dynamics and evolution of compact white-dwarf pairs are discussed in detail. Models and predictions of electron cyclotron masers from unipolar-inductor compact binaries and unipolar-inductor white-dwarf planetary systems are presented. Einstein-Laub effects in compact binaries are briefly discussed.

  14. Merging Compact Binaries in Hierarchical Triple Systems: Resonant Excitation of Binary Eccentricity

    CERN Document Server

    Liu, Bin; Yuan, Ye-Fei

    2015-01-01

    The merging of compact binaries play an important role in astrophysical context. The gravitational waves takes the angular momentum off the merging binary, which makes the orbit of the inner binary shrink. In this work, we study the secular dynamics of merging binary with a small perturber in hierarchical triple systems. From our numerical calculations, we find that the triple system goes through a resonant state between the apsidal precession rates of two orbits during the orbital decay, and the eccentricity of the inner orbit is excited, as well as the corresponding gravita- tional wave frequency. Our numerical results could be understood under the linear approximation of small orbital eccentricities and coplanar configuration. Especially, the resonant condition and the excited eccentricity can be estimated analytically.

  15. The Evolution of Compact Binary Star Systems

    Directory of Open Access Journals (Sweden)

    Yungelson, Lev R.

    2006-12-01

    Full Text Available We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs, neutron stars (NSs, and black holes (BHs. Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA. Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.

  16. Pressure-induced instability of magnetic order in Kondo-lattice system. Neutron diffraction study of the pseudo-binary alloy system Ce(Ru sub 0 sub . sub 9 sub 0 Rh sub 0 sub . sub 1 sub 0) sub 2 (Si sub 1 sub - sub y Ge sub y) sub 2

    CERN Document Server

    Watanabe, K; Kanadani, C; Taniguchi, T; Kawarazaki, S; Uwatoko, Y; Kadowaki, H

    2003-01-01

    Neutron diffraction experiments have been carried out to study the nature of the magnetic order of the pseudo-binary alloy system Ce(Ru sub 0 sub . sub 9 sub 0 Rh sub 0 sub . sub 1 sub 0) sub 2 (Si sub 1 sub - sub y Ge sub y) sub 2. Response of the ordered atomic magnetic moment, mu, the transition temperature, T sub N , and the magnitude of the magnetic modulation vector, q, to the chemical pressure and also to the applied hydrostatic pressure, P, were examined at low temperatures. When y changes, all of mu, T sub N and q show a sudden alteration of the manner of the y-dependence at around y - 0.08. The P-dependence of q shows quite different features for different y's of 0.0, 0.2 and 0.25. On the basis of these observations the possibility of a pressure-induced alternation of the magnetic regime of the order is discussed. (author)

  17. NONLINEAR TIDES IN CLOSE BINARY SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Weinberg, Nevin N. [Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Arras, Phil [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Quataert, Eliot; Burkart, Josh, E-mail: nevin@mit.edu [Astronomy Department and Theoretical Astrophysics Center, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States)

    2012-06-01

    We study the excitation and damping of tides in close binary systems, accounting for the leading-order nonlinear corrections to linear tidal theory. These nonlinear corrections include two distinct physical effects: three-mode nonlinear interactions, i.e., the redistribution of energy among stellar modes of oscillation, and nonlinear excitation of stellar normal modes by the time-varying gravitational potential of the companion. This paper, the first in a series, presents the formalism for studying nonlinear tides and studies the nonlinear stability of the linear tidal flow. Although the formalism we present is applicable to binaries containing stars, planets, and/or compact objects, we focus on non-rotating solar-type stars with stellar or planetary companions. Our primary results include the following: (1) The linear tidal solution almost universally used in studies of binary evolution is unstable over much of the parameter space in which it is employed. More specifically, resonantly excited internal gravity waves in solar-type stars are nonlinearly unstable to parametric resonance for companion masses M' {approx}> 10-100 M{sub Circled-Plus} at orbital periods P Almost-Equal-To 1-10 days. The nearly static 'equilibrium' tidal distortion is, however, stable to parametric resonance except for solar binaries with P {approx}< 2-5 days. (2) For companion masses larger than a few Jupiter masses, the dynamical tide causes short length scale waves to grow so rapidly that they must be treated as traveling waves, rather than standing waves. (3) We show that the global three-wave treatment of parametric instability typically used in the astrophysics literature does not yield the fastest-growing daughter modes or instability threshold in many cases. We find a form of parametric instability in which a single parent wave excites a very large number of daughter waves (N Almost-Equal-To 10{sup 3}[P/10 days] for a solar-type star) and drives them as a single

  18. XZ And a semidetached asynchronous binary system

    Science.gov (United States)

    Manzoori, Davood

    2016-05-01

    In this work the light curves (LCs) solutions along with the radial velocity curve of the semidetached binary systemXZ And are presented using the PHOEBE program(ver 0.31a). Absolute parameters of the stellar components were then determined, enabling us to discuss structure and evolutionary status of the system. The analysis indicates that the primary is a non-synchronous (i.e., F1 = 3.50 ± 0.01) Main Sequence (MS) star and the secondary is a bit more evolved, and fills its Roche critical surface. In addition, times of minima data (" O - C curve") were analyzed. Apart from an almost parabolic variation in the general trend of O - C data, which was attributed to a mass transfer from the secondary with the rate ˙2 = (9.52 ± 0.41) × 10-10 M ⊙ yr-1; two cyclic variations with mean periods of 34.8 ± 2.4 and 23.3 ± 3.0 yr, modulating the orbital period, were found, which were attributed to a third body orbiting around the system, and magnetic activity cycle effect, respectively.

  19. Milankovitch Cycles of Terrestrial Planets in Binary Star Systems

    Science.gov (United States)

    Forgan, Duncan

    2016-08-01

    The habitability of planets in binary star systems depends not only on the radiation environment created by the two stars, but also on the perturbations to planetary orbits and rotation produced by the gravitational field of the binary and neighbouring planets. Habitable planets in binaries may therefore experience significant perturbations in orbit and spin. The direct effects of orbital resonances and secular evolution on the climate of binary planets remain largely unconsidered. We present latitudinal energy balance modelling of exoplanet climates with direct coupling to an N Body integrator and an obliquity evolution model. This allows us to simultaneously investigate the thermal and dynamical evolution of planets orbiting binary stars, and discover gravito-climatic oscillations on dynamical and secular timescales. We investigate the Kepler-47 and Alpha Centauri systems as archetypes of P and S type binary systems respectively. In the first case, Earthlike planets would experience rapid Milankovitch cycles (of order 1000 years) in eccentricity, obliquity and precession, inducing temperature oscillations of similar periods (modulated by other planets in the system). These secular temperature variations have amplitudes similar to those induced on the much shorter timescale of the binary period. In the Alpha Centauri system, the influence of the secondary produces eccentricity variations on 15,000 year timescales. This produces climate oscillations of similar strength to the variation on the orbital timescale of the binary. Phase drifts between eccentricity and obliquity oscillations creates further cycles that are of order 100,000 years in duration, which are further modulated by neighbouring planets.

  20. Textured tape substrates from binary copper alloys with vanadium and yttrium for the epitaxial deposition of buffer and superconducting layers

    Science.gov (United States)

    Khlebnikova, Yu. V.; Rodionov, D. P.; Egorova, L. Yu.; Suaridze, T. R.

    2016-05-01

    The structure of tapes of binary Cu-0.6 wt % V and Cu-1 wt % Y alloys and texturing process of them in the course of cold deformation by rolling to 99% and subsequent recrystallizing annealing have been studied. The possibility of achieving the perfect cube texture in thin tapes made from binary copper-based alloys with vanadium and yttrium additions has in principle been shown. This opens the prospect of using them as substrates when manufacturing tapes of second-generation high-temperature superconductors. Optimum annealing conditions for the studied alloys have been determined, which have made it possible to produce the perfect biaxial texture with a content of cube {001} ± 10° grains on the surfaces of textured tapes of more than 95%.

  1. Nanoassembly of Polydisperse Photonic Crystals based on Binary and Ternary Polymer Opal Alloys

    CERN Document Server

    Zhao, Qibin; Schafer, Christian; Spahn, Peter; Gallei, Markus; Herrmann, Lars; Petukhov, Andrei; Baumberg, Jeremy J

    2016-01-01

    Ordered binary and ternary photonic crystals, composed of different sized polymer-composite spheres with diameter ratios up to 120%, are generated using bending induced oscillatory shearing (BIOS). This viscoelastic system creates polydisperse equilibrium structures, producing mixed opaline colored films with greatly reduced requirements for particle monodispersity, and very different sphere size ratios, compared to other methods of nano-assembly.

  2. Progenitor models of Wolf-Rayet+O binary systems

    NARCIS (Netherlands)

    Petrovic, J.; Langer, N.

    2007-01-01

    Since close WR+O binaries are the result of a strong interaction of both stars in massive close binary systems, they can be used to constrain the highly uncertain mass and angular momentum budget during the major mass- transfer phase. We explore the progenitor evolution of the three best suited WR+O

  3. Recent progress in perpendicularly magnetized Mn-based binary alloy films

    Science.gov (United States)

    Zhu, Li-Jun; Nie, Shuai-Hua; Zhao, Jian-Hua

    2013-11-01

    In this article, we review the recent progress in growth, structural characterizations, magnetic properties, and related spintronic devices of tetragonal MnxGa and MnxAl thin films with perpendicular magnetic anisotropy. First, we present a brief introduction to the demands for perpendicularly magnetized materials in spintronics, magnetic recording, and permanent magnets applications, and the most promising candidates of tetragonal MnxGa and MnxAl with strong perpendicular magnetic anisotropy. Then, we focus on the recent progress of perpendicularly magnetized MnxGa and MnxAl respectively, including their lattice structures, bulk synthesis, epitaxial growth, structural characterizations, magnetic and other spin-dependent properties, and spintronic devices like magnetic tunneling junctions, spin valves, and spin injectors into semiconductors. Finally, we give a summary and a perspective of these perpendicularly magnetized Mn-based binary alloy films for future applications.

  4. Effects of G-Jitter on Directional Solidification of a Binary Alloy

    Science.gov (United States)

    Benjapiyaporn, C.; Timchenko, V.; deVahlDavis, G.; deGroh, H. C., III

    1999-01-01

    A study of directional solidification of a weak binary alloy (specifically, Bi - 1 at% Sn) based on the fixed grid single domain approach is being undertaken. The enthalpy method is used to solve for the temperature field over the computational domain including both the solid and liquid phases; latent heat evolution is treated with the aid of an effective specific heat coefficient. A source term accounting for the release of solute into the liquid during solidification has been incorporated into the solute transport equation. The vorticity-stream function formulation is used to describe thermo-solutal convection in the liquid region. In this paper we present a numerical simulation of g-jitter. A background gravity of 1 microgram has been assumed, and new results for the effects of periodic disturbances over a range of amplitudes and frequencies on solute field and segregation have been presented.

  5. Phase field simulation of the columnar dendritic growth and microsegregation in a binary alloy

    Institute of Scientific and Technical Information of China (English)

    Li Jun-Jie; Wang Jin-Cheng; Yang Gen-Cang

    2008-01-01

    This paper applies a phase field model for polycrystalline solidification in binary alloys to simulate the formation and growth of the columnar dendritic array under the isothermal and constant cooling conditions.The solidification process and microsegregation in the mushy zone are analysed in detail.It is shown that under the isothermal condition solidification will stop after the formation of the mushy zone,but dendritic coarsening will progress continuously,which results in the decrease of the total interface area.Under the constant cooling condition the mushy zone will solidify and coarsen simultaneously. For the constant cooling solidification,microsegregation predicted by a modified Brody Flemings model is compared with the simulation results.It is found that the Fourier number which characterizes microsegregation is different for regions with different microstructures.Dendritic coarsening and the larger area of interface should account for the enhanced Fourier number in the region with well developed second dendritic arms.

  6. Diffusion dominated process for the crystal growth of a binary alloy

    Science.gov (United States)

    Hu, Wen-Rui; Hirata, Akira; Nishizawa, Shin-ichi

    1996-11-01

    The pure diffusion process has been often used to study the crystal growth of a binary alloy in the microgravity environment. In the present paper, a geometric parameter, the ratio of the maximum deviation distance of curved solidification and melting interfaces from the plane to the radius of the crystal rod, was adopted as a small parameter, and the analytical solution was obtained based on the perturbation theory. The radial segregation of a diffusion dominated process was obtained for cases of arbitrary Peclet number in a region of finite extension with both a curved solidification interface and a curved melting interface. Two types of boundary conditions at the melting interface were analyzed. Some special cases such as infinite extension in the longitudinal direction and special range of Peclet number were reduced from the general solution and discussed in detail.

  7. Searching for Pulsars in Close Binary Systems

    CERN Document Server

    Jouteux, S; Stappers, B W; Jonker, P; Van der Klis, M

    2001-01-01

    We present a detailed mathematical analysis of the Fourier response of binary pulsar signals whose frequencies are modulated by circular orbital motion. The fluctuation power spectrum of such signals is found to be \

  8. Light and Life: Exotic Photosynthesis in Binary Star Systems

    CERN Document Server

    O'Malley-James, J T; Cockell, C S; Greaves, J S

    2011-01-01

    The potential for hosting photosynthetic life on Earth-like planets within binary/multiple stellar systems was evaluated by modelling the levels of photosynthetically active radiation (PAR) such planets receive. Combinations of M and G stars in: (i) close-binary systems; (ii) wide-binary systems and (iii) three-star systems were investigated and a range of stable radiation environments found to be possible. These environmental conditions allow for the possibility of familiar, but also more exotic forms of photosynthetic life, such as infrared photosynthesisers and organisms specialised for specific spectral niches.

  9. Investigations of binary and ternary phase change alloys for future memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Rausch, Pascal

    2012-09-13

    The understanding of phase change materials is of great importance because it enables us to predict properties and tailor alloys which might be even better suitable to tackle challenges of future memory applications. Within this thesis two topics have been approached: on the one hand the understanding of the alloy In{sub 3}Sb{sub 1}Te{sub 2} and on the other hand the so called resistivity drift of amorphous Ge-Sn-Te phase change materials. The main topic covers an in depth discussion of the ternary alloy In{sub 3}Sb{sub 1}Te{sub 2}. At first glance, this alloy does not fit into the established concepts of phase alloys: e.g. the existence of resonant bonding in the crystalline phase is not obvious and the number of p-electrons is very low compared to other phase change alloys. Furthermore amorphous phase change alloys with high indium content are usually not discussed in literature, an exception being the recent work by Spreafico et al. on InGeTe{sub 2}. For the first time a complete description of In{sub 3}Sb{sub 1}Te{sub 2} alloy is given in this work for the crystalline phase, amorphous phase and crystallization process. In addition comparisons are drawn to typical phase change materials like Ge{sub 2}Sb{sub 2}Te{sub 5}/GeTe or prototype systems like AgInTe{sub 2} and InTe. The second topic of this thesis deals with the issue of resistivity drift, i.e. the increase of resistivity of amorphous phase change alloys with aging. This drift effect greatly hampers the introduction of multilevel phase change memory devices into the market. Recently a systematic decrease of drift coefficient with stoichiometry has been observed in our group going from GeTe over Ge{sub 3}Sn{sub 1}Te{sub 4} to Ge{sub 2}Sn{sub 2}Te{sub 4}. These alloys are investigated with respect to constraint theory.

  10. In vitro and in vivo comparison of binary Mg alloys and pure Mg.

    Science.gov (United States)

    Myrissa, Anastasia; Agha, Nezha Ahmad; Lu, Yiyi; Martinelli, Elisabeth; Eichler, Johannes; Szakács, Gábor; Kleinhans, Claudia; Willumeit-Römer, Regine; Schäfer, Ute; Weinberg, Annelie-Martina

    2016-04-01

    Biodegradable materials are under investigation due to their promising properties for biomedical applications as implant material. In the present study, two binary magnesium (Mg) alloys (Mg2Ag and Mg10Gd) and pure Mg (99.99%) were used in order to compare the degradation performance of the materials in in vitro to in vivo conditions. In vitro analysis of cell distribution and viability was performed on discs of pure Mg, Mg2Ag and Mg10Gd. The results verified viable pre-osteoblast cells on all three alloys and no obvious toxic effect within the first two weeks. The degradation rates in in vitro and in vivo conditions (Sprague-Dawley® rats) showed that the degradation rates differ especially in the 1st week of the experiments. While in vitro Mg2Ag displayed the fastest degradation rate, in vivo, Mg10Gd revealed the highest degradation rate. After four weeks of in vitro immersion tests, the degradation rate of Mg2Ag was significantly reduced and approached the values of pure Mg and Mg10Gd. Interestingly, after 4 weeks the estimated in vitro degradation rates approximate in vivo values. Our systematic experiment indicates that a correlation between in vitro and in vivo observations still has some limitations that have to be considered in order to perform representative in vitro experiments that display the in vivo situation.

  11. Interaction behavior between binary xCe-yNd alloy and HT9

    Science.gov (United States)

    Kim, Jun Hwan; Cheon, Jin Sik; Lee, Byoung Oon; Kim, June Hyung

    2016-10-01

    Studies were carried out to investigate the role of Ce and Nd, contained inside metal fuel during reactor operation, and their effect on the Fuel-Cladding Chemical Interaction (FCCI) phenomenon, which limits fuel performance in the Sodium-cooled Fast Reactor (SFR). Binary model alloys of xCe-yNd were manufactured, and then diffusion couple tests with HT9 (12Cr-1MoWV) ferritic-martensitic cladding material were carried out at a temperature of 660 °C for up to 25 h. The results showed that both Ce and Nd reacted with Fe in the cladding material to form an interaction layer. Analysis of the microstructure and reaction kinetics revealed that Fe in the cladding material rapidly migrates into Ce to form eutectic reaction, leaving a Fe depleted zone, in which Ce substitutes. In the case of Nd element, a typical solid-solid diffusion process governed to form a Fe17Nd2 type intermetallic compound. Synergism between Ce and Nd occurred so that the reaction thickness was increased, reaching the maximum reaction thickness in the case of the xCe-yNd alloy, whose composition was nearly 1:1.

  12. FORMATION REGULARITIES OF PHASE COMPOSITION, STRUCTURE AND PROPERTIES DURING MECHANICAL ALLOYING OF BINARY ALUMINUM COMPOSITES

    Directory of Open Access Journals (Sweden)

    F. G. Lovshenko

    2015-01-01

    Full Text Available The paper presents investigation results pertaining to  ascertainment of formation regularities of phase composition and structure during mechanical alloying of binary aluminium composites/substances. The invetigations have been executed while applying a wide range of methods, devices and equipment used in modern material science. The obtained data complement each other. It has been established that presence of oxide and hydro-oxide films on aluminium powder  and introduction of surface-active substance in the composite have significant effect on mechanically and thermally activated phase transformations and properties of semi-finished products.  Higher fatty acids have been used as a surface active substance.The mechanism of mechanically activated solid solution formation has been identified. Its essence is  a formation of  specific quasi-solutions at the initial stage of processing. Mechanical and chemical interaction between components during formation of other phases has taken place along with dissolution  in aluminium while processing powder composites. Granule basis is formed according to the dynamic recrystallization mechanism and possess submicrocrystal structural type with the granule dimension basis less than 100 nm and the grains are divided in block size of not more than 20 nm with oxide inclusions of 10–20 nm size.All the compounds  with the addition of  surface-active substances including aluminium powder without alloying elements obtained by processing in mechanic reactor are disperse hardened. In some cases disperse hardening is accompanied by dispersive and solid solution hardnening process. Complex hardening predetermines a high temperature of recrystallization in mechanically alloyed compounds,  its value exceeds 400 °C.

  13. Interdiffusion in binary cast and powders W-Re and Mo-Re alloys

    International Nuclear Information System (INIS)

    Concentration dependences of diffusion coefficients in the cast and powder alloys of the W-Re and Mo-Re systems are obtained. It is shown, that in spite of the fact that the diffusion coefficients values in dispersed materials are higher than in the cast ones, the peculiarities of the concentration dependences are common for both cases

  14. Experimental investigation and thermodynamic assessment of the Mn–In binary system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L.Y. [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Wang, J., E-mail: wangjiang158@163.com [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Zhu, C.F.; Cheng, G.; Tang, C.Y. [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Rao, G.H., E-mail: rgh@guet.edu.cn [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Zhou, H.Y. [Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China); School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China)

    2015-05-10

    Highlights: • Three invariant reactions and liquidus were determined by thermal analysis. • The Mn–In binary system was assessed using CALPHAD method. • A set of self-consistent thermodynamic parameters was obtained. • The calculation results agree well with phase equilibria and thermodynamic data. - Abstract: In the present work, sixteen Mn–In alloys were investigated experimentally by means of thermal analysis and X-ray diffraction techniques. The temperatures of the invariant reactions and liquidus in the Mn–In binary system were determined. Based on the experimental results obtained in the present work and the critical review of the available experimental data from the published literature, the Mn–In binary system was assessed thermodynamically using the CALPHAD method. The solution phases including liquid, α-Mn, β-Mn, γ-Mn, δ-Mn and tetragonal-A6(In), are modeled by the substitutional solution model and their excess Gibbs energies are expressed with the Redlich–Kister polynomial. The intermetallic compound, InMn{sub 3}, is treated as a stoichiometric compound. A set of self-consistent thermodynamic parameters obtained finally to describe the Gibbs energies of various phases in the Mn–In binary system can be used to reproduce well the phase equilibria and thermodynamic data.

  15. KOI-3278: a self-lensing binary star system.

    Science.gov (United States)

    Kruse, Ethan; Agol, Eric

    2014-04-18

    Over 40% of Sun-like stars are bound in binary or multistar systems. Stellar remnants in edge-on binary systems can gravitationally magnify their companions, as predicted 40 years ago. By using data from the Kepler spacecraft, we report the detection of such a "self-lensing" system, in which a 5-hour pulse of 0.1% amplitude occurs every orbital period. The white dwarf stellar remnant and its Sun-like companion orbit one another every 88.18 days, a long period for a white dwarf-eclipsing binary. By modeling the pulse as gravitational magnification (microlensing) along with Kepler's laws and stellar models, we constrain the mass of the white dwarf to be ~63% of the mass of our Sun. Further study of this system, and any others discovered like it, will help to constrain the physics of white dwarfs and binary star evolution. PMID:24744369

  16. Concentration dependent wetting by aniline-ethanol binary system

    Directory of Open Access Journals (Sweden)

    Vinjanampaty Madhurima

    2014-07-01

    Full Text Available Wetting of five substrates namely glass, indium tin oxide, aluminum oxide, hylam and teflon by aniline-ethanol binary system over the entire concentration range is studied using contact angle measurements. Rapid wetting of the substrates, especially hylam in the aniline rich region is understood in terms of the surface energies of the substrates and the intermolecular interactions between the two moieties. FTIR, dielectric and conformational analysis are used to study the molecular interactions in the binary system

  17. Excess Molar Volume of Binary Systems Containing Mesitylene

    OpenAIRE

    Morávková, L. (Lenka); Sedláková, Z.

    2013-01-01

    This paper presents a review of density measurements for binary systems containing 1,3,5-trimethylbenzene (mesitylene) with a variety of organic compounds at atmospheric pressure. Literature data of the binary systems were divided into nine basic groups by the type of contained organic compound with mesitylene. The excess molar volumes calculated from the experimental density values have been compared with literature data. Densities were measured by a few experimental methods, namely using a ...

  18. Iterative Solution for Systems of Nonlinear Two Binary Operator Equations

    Institute of Scientific and Technical Information of China (English)

    ZHANGZhi-hong; LIWen-feng

    2004-01-01

    Using the cone and partial ordering theory and mixed monotone operator theory, the existence and uniqueness of solutions for some classes of systems of nonlinear two binary operator equations in a Banach space with a partial ordering are discussed. And the error estimates that the iterative sequences converge to solutions are also given. Some relevant results of solvability of two binary operator equations and systems of operator equations are imnroved and generalized.

  19. Performance of binary FSK data transmission systems

    Science.gov (United States)

    Batson, B. H.

    1973-01-01

    Matched-filter detection of binary signals is discussed in terms of the probability of bit error. The equations for the probability of error are derived for coherent phase shift keying, and coherent frequency shift keying (FSK). Suboptimum detection of FSK signals is also discussed for discriminators.

  20. Relating binary-star planetary systems to central configurations

    CERN Document Server

    Veras, Dimitri

    2016-01-01

    Binary-star exoplanetary systems are now known to be common, for both wide and close binaries. However, their orbital evolution is generally unsolvable. Special cases of the N-body problem which are in fact completely solvable include dynamical architectures known as central configurations. Here, I utilize recent advances in our knowledge of central configurations to assess the plausibility of linking them to coplanar exoplanetary binary systems. By simply restricting constituent masses to be within stellar or substellar ranges characteristic of planetary systems, I find that (i) this constraint reduces by over 90 per cent the phase space in which central configurations may occur, (ii) both equal-mass and unequal-mass binary stars admit central configurations, (iii) these configurations effectively represent different geometrical extensions of the Sun-Jupiter-Trojan-like architecture, (iv) deviations from these geometries are no greater than ten degrees, and (v) the deviation increases as the substellar masse...

  1. The Evolutionary Outcomes of Expansive Binary Asteroid Systems

    Science.gov (United States)

    McMahon, Jay W.

    2016-10-01

    Singly synchronous binary asteroid systems have several evolutionary end-states, which depend heavily on the BYORP effect. In the case of expansive BYORP, the binary system could evolve to become a wide asynchronous binary system (Jacobson, et al 2014), or the system could expand far enough to become disrupted to form a heliocentric pair (Vokrouhlicky et al 2008). Cuk et al (2011) found that upon expanding the secondary will quickly become asynchronous, and will end up re-establishing synchronous rotation with the opposite attitude, causing the binary orbit to subsequently contract. The distinction between these outcomes depends on whether the secondary asteroid stays synchronized, which keeps the BYORP effect active and the orbit expanding. As the orbit expands, the secondary libratation will expand, and the libration will also causes large variations in the binary orbit due to the elongation of the secondary. If the eccentricity and libration are bound to small enough values the system can expand significantly. This work discusses the stability of the libration and orbital motion as a binary expands from a wide variety of simulation runs with various parameters. We investigate how the strength of tides and BYORP change the stability of the librational motion; an important factor is the speed of BYORP expansion as slower expansion allows tides to have a more stabilizing effect. We also investigate the effect of heliocentric orbit semimajor axis and eccentricity. We find that resonances between the coupled orbit-libration frequencies and the heliocentric orbit cause instability in the binary orbit eccentricity which produces a strong preference for wide binary production, especially amongst retrograde binary systems. This instability also becomes stronger with large heliocentric eccentricities. Prograde binaries are more stable and can possible grow to become asteroid pairs. We find that even in the presence of tides, reestablishment of synchronous spin into a

  2. Construction of binary status information system using PC network

    International Nuclear Information System (INIS)

    Binary status information system is a part of establishing reactor parameter with Pc that function as MPR-30 Process Computer. Binary Alarm system, consist of interface hardware and input binary module terminal, prepare the information that be displayed in text message and graphical form. Monitor software give facilities that binary status of RSG-GAS components can be monitored using computer network (LAN). This program consist of two part : reside in server computer and reside in user computer. Program in server acquire data from interface and than store it in data base (Access file). Than, user computer read this file and display it in Dynamic Process and Instrumentation Diagram. The number of user computer can be more then one because data base was designed for multi-user operation

  3. Spectral modelling of the Alpha Virginis (Spica) binary system

    CERN Document Server

    Palate, M; Rauw, G; Harrington, D; Moreno, E

    2013-01-01

    Context: The technique of matching synthetic spectra computed with theoretical stellar atmosphere models to the observations is widely used in deriving fundamental parameters of massive stars. When applied to binaries, however, these models generally neglect the interaction effects present in these systems Aims: The aim of this paper is to explore the uncertainties in binary stellar parameters that are derived from single-star models Methods: Synthetic spectra that include the tidal perturbations and irradiation effects are computed for the binary system alpha Virginis (Spica) using our recently-developed CoMBiSpeC model. The synthetic spectra are compared to S/N~2000 observations and optimum values of Teff and log(g) are derived. Results: The binary interactions have only a small effect on the strength of the photospheric absorption lines in Spica (<2% for the primary and <4% for the secondary). These differences are comparable to the uncertainties inherent to the process of matching synthetic spectra ...

  4. High energy gamma-rays from massive binary systems

    CERN Document Server

    Bednarek, W

    2008-01-01

    During last years a few massive binary systems have been detected in the TeV gamma-rays. This gamma-ray emission is clearly modulated with the orbital periods of these binaries suggesting its origin inside the binary system. In this paper we summarize the anisotropic IC e-p pair cascade model as likely explanation of these observations. We consider scenarios in which particles are accelerated to relativistic energies, either due to the presence of an energetic pulsar inside the binary, or as a result of accretion process onto the compact object during which the jet is launched from the inner part of the accretion disk, or in collisions of stellar winds from the massive companions.

  5. Particle Based Alloying by Accumulative Roll Bonding in the System Al-Cu

    Directory of Open Access Journals (Sweden)

    Mathias Göken

    2011-11-01

    Full Text Available The formation of alloys by particle reinforcement during accumulative roll bonding (ARB, and subsequent annealing, is introduced on the basis of the binary alloy system Al-Cu, where strength and electrical conductivity are examined in different microstructural states. An ultimate tensile strength (UTS of 430 MPa for Al with 1.4 vol.% Cu was reached after three ARB cycles, which almost equals UTS of the commercially available Al-Cu alloy AA2017A with a similar copper content. Regarding electrical conductivity, the UFG structure had no significant influence. Alloying of aluminum with copper leads to a linear decrease in conductivity of 0.78 µΩ∙cm/at.% following the Nordheim rule. On the copper-rich side, alloying with aluminum leads to a slight strengthening, but drastically reduces conductivity. A linear decrease of electrical conductivity of 1.19 µΩ∙cm/at.% was obtained.

  6. A classification system for tableting behaviors of binary powder mixtures

    OpenAIRE

    Changquan Calvin Sun

    2016-01-01

    The ability to predict tableting properties of a powder mixture from individual components is of both fundamental and practical importance to the efficient formulation development of tablet products. A common tableting classification system (TCS) of binary powder mixtures facilitates the systematic development of new knowledge in this direction. Based on the dependence of tablet tensile strength on weight fraction in a binary mixture, three main types of tableting behavior are identified. Eac...

  7. A quintuple star system containing two eclipsing binaries

    Science.gov (United States)

    Rappaport, S.; Lehmann, H.; Kalomeni, B.; Borkovits, T.; Latham, D.; Bieryla, A.; Ngo, H.; Mawet, D.; Howell, S.; Horch, E.; Jacobs, T. L.; LaCourse, D.; Sódor, Á.; Vanderburg, A.; Pavlovski, K.

    2016-10-01

    We present a quintuple star system that contains two eclipsing binaries. The unusual architecture includes two stellar images separated by 11 arcsec on the sky: EPIC 212651213 and EPIC 212651234. The more easterly image (212651213) actually hosts both eclipsing binaries which are resolved within that image at 0.09 arcsec, while the westerly image (212651234) appears to be single in adaptive optics (AO), speckle imaging, and radial velocity (RV) studies. The `A' binary is circular with a 5.1-d period, while the `B' binary is eccentric with a 13.1-d period. The γ velocities of the A and B binaries are different by ˜10 km s-1. That, coupled with their resolved projected separation of 0.09 arcsec, indicates that the orbital period and separation of the `C' binary (consisting of A orbiting B) are ≃65 yr and ≃25 au, respectively, under the simplifying assumption of a circular orbit. Motion within the C orbit should be discernible via future RV, AO, and speckle imaging studies within a couple of years. The C system (i.e. 212651213) has an RV and proper motion that differ from that of 212651234 by only ˜1.4 km s-1 and ˜3 mas yr-1. This set of similar space velocities in three dimensions strongly implies that these two objects are also physically bound, making this at least a quintuple star system.

  8. Numerical simulation of boundary heat flow effects on directional solidification microstructure of a binary alloy

    Directory of Open Access Journals (Sweden)

    Xue Xiang

    2010-08-01

    Full Text Available The boundary heat flow has important significance for the microstructures of directional solidified binary alloy. Interface evolution of the directional solidified microstructure with different boundary heat flow was discussed. In this study, only one interface was allowed to have heat flow, and Neumann boundary conditions were imposed at the other three interfaces. From the calculated results, it was found that different boundary heat flows will result in different microstructures. When the boundary heat flow equals to 20 W·cm-2, the growth of longitudinal side branches is accelerated and the growth of transverse side branches is restrained, and meanwhile, there is dendritic remelting in the calculation domain. When the boundary heat flow equals to 40 W·cm-2, the growths of the transverse and longitudinal side branches compete with each other, and when the boundary heat flow equals to 100-200 W·cm-2, the growth of transverse side branches dominates absolutely. The temperature field of dendritic growth was analyzed and the relation between boundary heat flow and temperature field was also investigated.

  9. Effect of g-jitter on Directional Solidification of a Binary Alloy

    Science.gov (United States)

    Santiviriyapanich, P.; Benjapiyaporn, C.; Timchenko, V.; deVahlDavis, G.; Leonardi, E.; deGroh, H. C., III

    2000-01-01

    A study of directional solidification of a weak binary alloy (specifically, Bi - 1 at% Sn) based on the fixed grid single domain approach is being undertaken. The enthalpy method is used to solve for the temperature field over the computational domain including both the solid and liquid phases; latent heat evolution is treated with the aid of an effective specific heat coefficient. A source term accounting for the release of solute into the liquid during solidification has been incorporated into the solute transport equation. The vorticity-stream function formulation is used to describe thermosolutal convection in the liquid region. In this paper we present a numerical simulation of g-jitter: the small, rapid fluctuations in gravitational acceleration which may be experienced in an orbiting space vehicle. A background gravity of 1 micro-g has been assumed, and new results for the effects of orientation angle of the periodic disturbances over a range of amplitudes and frequencies on solute field and segregation have been presented.

  10. Numerical simulation of boundary heat flow effects on directional solidification microstructure of a binary alloy

    Institute of Scientific and Technical Information of China (English)

    Xue Xiang; Tang Jinjun

    2010-01-01

    The boundary heat flow has important significance for the microstructures of directional solidified binary alloy. Interface evolution of the directional solidified microstructure with different boundary heat flow was discussed. In this study, only one interface was allowed to have heat flow, and Neumann boundary conditions were imposed at the other three interfaces. From the calculated results, it was found that different boundary heat flows will result in different microstructures. When the boundary heat flow equals to 20 W-cm-2, the growth of longitudinal side branches is accelerated and the growth of transverse side branches is restrained, and meanwhile, there is dendritic remelting in the calculation domain. When the boundary heat flow equals to 40 W-cm-2, the growths of the transverse and longitudinal side branches compete with each other, and when the boundary heat flow equals to 100-200 W-cm-2, the growth of transverse side branches dominates absolutely. The temperature field of dendritic growth was analyzed and the relation between boundary heat flow and temperature field was also investigated.

  11. Efficient analytical expressions for dynamic structure of liquid binary alloys: K–Cs as a case study

    International Nuclear Information System (INIS)

    A fitting scheme for analysis of collective dynamics in liquid binary alloys is proposed. It is based on explicit treatment of contributions from three relaxing modes and two types of propagating modes to the partial density–density time correlation functions and corresponding partial dynamic structure factors. Exact sum rules for each partial dynamic structure factor were taken into account. The proposed fitting scheme was applied to the liquid equimolar K–Cs alloy. Analysis of simulation-derived partial time correlation functions as well as of their corresponding Bhatia–Thornton ‘number-concentration’ combinations allowed dispersion and damping of the two branches of collective excitations and the behaviour of relaxing modes in a wide range of wave numbers to be obtained. A comparison with the inelastic neutron-scattering intensities for the liquid K–Cs alloy was performed. (paper)

  12. Structure, elastic and bonding properties of hcp ZrxTi1-x binary alloy from first-principles calculations

    CERN Document Server

    Songjun, Hou; Sunchao, Huang; Zhi, Zeng

    2015-01-01

    First principles calculations were performed to study the structural, elastic, and bonding properties of hcp ZrxTi1-x binary alloy. The special quasi- random structure (SQS) method is employed to mimic the random hcp ZrxTi1-x alloy. It is found that Bulk modulus, B, Young's modulus, E, and shear modulus, G, exhibit decreasing trends as increasing the amount of Zr. A ductile behavior ZrxTi1-x is predicted in the whole composition range. In terms of Mulliken charge analisis, we found that the element Ti behaves much more electronegative than Zr in hcp ZrxTi1-x alloy, and the charge transfer of an atom is approximately linear to the amount of other element atom surrounding it.

  13. A Quintuple Star System Containing Two Eclipsing Binaries

    CERN Document Server

    Rappaport, S; Kalomeni, B; Borkovits, T; Latham, D; Bieryla, A; Ngo, H; Mawet, D; Howell, S; Horch, E; Jacobs, T L; LaCourse, D; Sodor, A; Vanderburg, A; Pavlovski, K

    2016-01-01

    We present a quintuple star system that contains two eclipsing binaries. The unusual architecture includes two stellar images separated by 11" on the sky: EPIC 212651213 and EPIC 212651234. The more easterly image (212651213) actually hosts both eclipsing binaries which are resolved within that image at 0.09", while the westerly image (212651234) appears to be single in adaptive optics (AO), speckle imaging, and radial velocity (RV) studies. The 'A' binary is circular with a 5.1-day period, while the 'B' binary is eccentric with a 13.1-day period. The gamma velocities of the A and B binaries are different by ~10 km/s. That, coupled with their resolved projected separation of 0.09", indicates that the orbital period and separation of the 'C' binary (consisting of A orbiting B) are ~65 years and ~25 AU, respectively, under the simplifying assumption of a circular orbit. Motion within the C orbit should be discernible via future RV, AO, and speckle imaging studies within a couple of years. The C system (i.e., 21...

  14. KIC 7177553: a quadruple system of two close binaries

    CERN Document Server

    Lehmann, H; Rappaport, S A; Ngo, H; Mawet, D; Csizmadia, Sz; Forgacs-Dajka, E

    2016-01-01

    KIC 7177553 was observed by the Kepler satellite to be an eclipsing eccentric binary star system with an 18-day orbital period. Recently, an eclipse timing study of the Kepler binaries has revealed eclipse timing variations in this object with an amplitude of about 100 sec, and an outer period of 529 days. The implied mass of the third body is that of a superJupiter, but below the mass of a brown dwarf. We therefore embarked on a radial velocity study of this binary to determine its system configuration and to check the hypothesis that it hosts a giant planet. From the radial velocity measurements, it became immediately obvious that the same Kepler target contains another eccentric binary, this one with a 16.5-day orbital period. Direct imaging using adaptive optics reveals that the two binaries are separated by 0.4 arcsec (about 167 AU), and have nearly the same magnitude (to within 2%). The close angular proximity of the two binaries, and very similar Gamma velocities, strongly suggest that KIC 7177553 is o...

  15. Relating binary-star planetary systems to central configurations

    Science.gov (United States)

    Veras, Dimitri

    2016-11-01

    Binary-star exoplanetary systems are now known to be common, for both wide and close binaries. However, their orbital evolution is generally unsolvable. Special cases of the N-body problem which are in fact completely solvable include dynamical architectures known as central configurations. Here, I utilize recent advances in our knowledge of central configurations to assess the plausibility of linking them to coplanar exoplanetary binary systems. By simply restricting constituent masses to be within stellar or substellar ranges characteristic of planetary systems, I find that (i) this constraint reduces by over 90 per cent the phase space in which central configurations may occur, (ii) both equal-mass and unequal-mass binary stars admit central configurations, (iii) these configurations effectively represent different geometrical extensions of the Sun-Jupiter-Trojan-like architecture, (iv) deviations from these geometries are no greater than 10°, and (v) the deviation increases as the substellar masses increase. This study may help restrict future stability analyses to architectures which resemble exoplanetary systems, and might hint at where observers may discover dust, asteroids and/or planets in binary-star systems.

  16. Stochastic Background of Gravitational Waves Generated by Compact Binary Systems

    CERN Document Server

    Evangelista, E F D

    2015-01-01

    Binary Systems are the most studied sources of gravitational waves. The mechanisms of emission and the behavior of the orbital parameters are well known and can be written in analytic form in several cases. Besides, the strongest indication of the existence of gravitational waves has arisen from the observation of binary systems. On the other hand, when the detection of gravitational radiation becomes a reality, one of the observed pattern of the signals will be probably of stochastic background nature, which are characterized by a superposition of signals emitted by many sources around the universe. Our aim here is to develop an alternative method of calculating such backgrounds emitted by cosmological compact binary systems during their periodic or quasiperiodic phases. We use an analogy with a problem of Statistical Mechanics in order to perform this sum as well as taking into account the temporal variation of the orbital parameters of the systems. Such a kind of background is of particular importance sinc...

  17. Preparation of low-platinum-content platinum-nickel, platinum-cobalt binary alloy and platinum-nickel-cobalt ternary alloy catalysts for oxygen reduction reaction in polymer electrolyte fuel cells

    Science.gov (United States)

    Li, Mu; Lei, Yanhua; Sheng, Nan; Ohtsuka, Toshiaki

    2015-10-01

    A series of low-platinum-content platinum-nickel (Pt-Ni), platinum-cobalt (Pt-Co) binary alloys and platinum-nickel-cobalt (Pt-Ni-Co) ternary alloys electrocatalysts were successfully prepared by a three-step process based on electrodeposition technique and studied as electrocatalysts for oxygen reduction reaction (ORR) in polymer-electrolyte fuel cells. Kinetics of ORR was studied in 0.5 M H2SO4 solution on the Pt-Ni, Pt-Co and Pt-Ni-Co alloys catalysts using rotating disk electrode technique. Both the series of Pt-Ni, Pt-Co binary alloys and the Pt-Ni-Co ternary alloys catalysts exhibited an obvious enhancement of ORR activity in comparison with pure Pt. The significant promotion of ORR activities of Pt-Ni and Pt-Co binary alloys was attributed to the enhancement of the first electron-transfer step, whereas, Pt-Ni-Co ternary alloys presented a more complicated mechanism during the electrocatalysis process but a much more efficient ORR activities than the binary alloys.

  18. Understanding the evolution of close binary systems with radio pulsars

    CERN Document Server

    Benvenuto, O G; Horvath, J E

    2014-01-01

    We calculate the evolution of close binary systems (CBSs) formed by a neutron star (behaving as a radio pulsar) and a normal donor star, evolving either to helium white dwarf (HeWD) or ultra short orbital period systems. We consider X-ray irradiation feedback and evaporation due to radio pulsar irradiation. We show that irradiation feedback leads to cyclic mass transfer episodes, allowing CBSs to be observed in-between as binary radio pulsars under conditions in which standard, non-irradiated models predict the occurrence of a low mass X-ray binary. This behavior accounts for the existence of a family of eclipsing binary systems known as redbacks. We predict that redback companions should almost fill their Roche lobe, as observed in PSR J1723-2837. This state is also possible for systems evolving with larger orbital periods. Therefore, binary radio pulsars with companion star masses usually interpreted as larger than expected to produce HeWDs may also result in such {\\it quasi - Roche Lobe Overflow} states, r...

  19. Nonparametric statistical structuring of knowledge systems using binary feature matches

    DEFF Research Database (Denmark)

    Mørup, Morten; Glückstad, Fumiko Kano; Herlau, Tue;

    2014-01-01

    Structuring knowledge systems with binary features is often based on imposing a similarity measure and clustering objects according to this similarity. Unfortunately, such analyses can be heavily influenced by the choice of similarity measure. Furthermore, it is unclear at which level clusters have...... statistical support and how this approach generalizes to the structuring and alignment of knowledge systems. We propose a non-parametric Bayesian generative model for structuring binary feature data that does not depend on a specific choice of similarity measure. We jointly model all combinations of binary...... matches and structure the data into groups at the level in which they have statistical support. The model naturally extends to structuring and aligning an arbitrary number of systems. We analyze three datasets on educational concepts and their features and demonstrate how the proposed model can both...

  20. Understanding Gravitational Waves from Inspiral Binary Systems and its Detection

    CERN Document Server

    Antelis, Javier M

    2016-01-01

    The discovery of the events GW150926 and GW151226 has experimentally confirmed the existence of gravitational waves (GW) and has demonstrated the existence of binary stellar-mass black hole systems. This finding marks the beginning of a new era that will reveal unexpected features of our universe. This work presents a basic insight to the fundamental theory of GW emitted by inspiral binary systems and describes the scientific and technological efforts developed to measure this waves using the interferometer-based detector called LIGO. Subsequently, the work proposes a comprehensive data analysis methodology based on the matched filter algorithm which aims to detect GW signals emitted by inspiral binary systems of astrophysical sources. The method is validated with freely available LIGO data which contain injected GW signals. Results of experiments performed to assess detection carried out show that the method was able to recover the 85% of the injected GW.

  1. Orbital Architectures of Planet-Hosting Binary Systems

    Science.gov (United States)

    Dupuy, Trent J.; Kratter, Kaitlin M.

    2016-01-01

    We present the first results from our Keck AO astrometric monitoring of Kepler Prime Mission planet-hosting binary systems. Observational biases in exoplanet discovery have long left the frequency, properties, and provenance of planets in most binary systems largely unconstrained. Recent results from our ongoing survey of a volume-limited sample of Kepler planet hosts indicate that binary companions at solar-system scales of 20-100 AU suppress the occurrence of planetary systems at a rate of 30-100%. However, some planetary systems do survive in binaries, and determining these systems' orbital architectures is key to understanding why. As a demonstration of this new approach to testing ideas of planet formation, we present a detailed analysis of the triple star system Kepler-444 (HIP 94931) that hosts five Ganymede- to Mars-sized planets. By combining our high-precision astrometry with radial velocities from HIRES we discover a highly eccentric stellar orbit that would have made this a seemingly hostile site for planet formation. This either points to an extremely robust and efficient planet formation mechanism or a rare case of favorable initial conditions. Such broader implications will be addressed by determining orbital architectures for our larger statistical sample of Kepler planet-hosting systems that have stellar companions on solar system scales.

  2. Binary systems solubilities of inorganic and organic compounds

    CERN Document Server

    Stephen, H

    1963-01-01

    Solubilities of Inorganic and Organic Compounds, Volume 1: Binary Systems, Part 1 is part of an approximately 5,500-page manual containing a selection from the International Chemical Literature on the Solubilities of Elements, Inorganic Compounds, Metallo-organic and Organic Compounds in Binary, Ternary and Multi-component Systems. A careful survey of the literature in all languages by a panel of scientists specially appointed for the task by the U.S.S.R. Academy of Sciences, Moscow, has made the compilation of this work possible. The complete English edition in five separately bound volumes w

  3. The effects of rapid solidification on microstructure and hydrogen sorption properties of binary BCC Ti–V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Suwarno, S., E-mail: S.Suwarno@uu.nl [Department of Materials Science and Engineering, NTNU, NO-7491, Trondheim (Norway); Solberg, J.K. [Department of Materials Science and Engineering, NTNU, NO-7491, Trondheim (Norway); Maehlen, J.P. [Institute for Energy Technology, P.O. Box 40, NO-2027, Kjeller (Norway); Krogh, B. [Statoil ASA Research Centre, Rotvoll, NO-7005, Trondheim (Norway); Yartys, V.A. [Department of Materials Science and Engineering, NTNU, NO-7491, Trondheim (Norway); Institute for Energy Technology, P.O. Box 40, NO-2027, Kjeller (Norway)

    2014-01-05

    Highlights: • Effect of quenching rate and Ti/V ratio on the phase-structural composition. • Grain size refinement in the rapidly solidified Ti–V alloys. • Hydrogen storage properties of rapidly solidified binary Ti–V. • Mechanism of phase transformations in the hydrides of the RS Ti–V alloys. -- Abstract: The main purpose of the present work was to study the effect of rapid solidification (RS) on the microstructure and hydrogen storage properties of body centred cubic (BCC) Ti rich Ti–V alloys (Ti{sub 1−x}V{sub x}, x = 0.1–0.3). Ribbons were prepared by melt spinning at spinner rotation velocities of 1000–3000 rpm. Ribbon morphology and microstructure were found to depend on the vanadium content and spinner velocity. For Ti{sub 0.8}V{sub 0.2}, the relation between the ribbon thickness and velocity can be expressed as a power law function, indicating that, during solidification of the Ti–V ribbons, heat transfer at the interface between spinner and ribbon controls the heat extraction. Temperature desorption spectroscopy (TDS) and in situ synchrotron (SR-XRD) studies of the RS alloys showed that hydrogen desorption from the RS alloy hydrides occurred at lower temperatures than from the as cast alloys. RS caused a microscale chemical element separation in the alloys, which depends on the vanadium content and the spinner velocity. In addition, ribbon recalescence was observed to cause nanoscale chemical redistribution trough spinodal decomposition. These two last features were proposed to be the reasons for the observed thermal destabilisation.

  4. X-ray binary systems - Ariel V SSI observations

    International Nuclear Information System (INIS)

    The basis of our current theoretical understanding of galactic x-ray sources is reviewed. Models are outlined involving close binary systems containing a compact object accreting mass which has been lost from the nondegenerate star by a variety of mechanisms. The present status of galactic x-ray astronomy is discussed, with emphasis on the links between established observational categories and the characteristics of the proposed models. Observational results, consisting primarily of extended x-ray light curves derived from analysis of Ariel V SSI data are presented for two main classes of galactic x-ray source: (i) high-mass x-ray binaries containing an early-type giant or supergiant star; (ii) low-mass x-ray binaries in which the nondegenerate star is a late-type dwarf. For the high-mass binaries emphasis is placed on the determination and improvement of the orbital parameters; for the low-mass binaries, where a less complete picture is available, the discussion centres on the type of system involved, taking into account the optical observations of the source. Finally, the properties of two further categories - the sources in the galactic bulge and those associated with dwarf novae - are discussed as examples of rather different types of galactic x-ray emitter. In the case of the galactic bulge sources current observations have not led so far to a clear picture of the nature of the systems involved, indeed their binary membership is not established. X-ray emission from dwarf novae and related objects is a relatively recent discovery and represents the opening up of a new field of galactic x-ray astronomy. (author)

  5. Hydrogen storage systems from waste Mg alloys

    Science.gov (United States)

    Pistidda, C.; Bergemann, N.; Wurr, J.; Rzeszutek, A.; Møller, K. T.; Hansen, B. R. S.; Garroni, S.; Horstmann, C.; Milanese, C.; Girella, A.; Metz, O.; Taube, K.; Jensen, T. R.; Thomas, D.; Liermann, H. P.; Klassen, T.; Dornheim, M.

    2014-12-01

    The production cost of materials for hydrogen storage is one of the major issues to be addressed in order to consider them suitable for large scale applications. In the last decades several authors reported on the hydrogen sorption properties of Mg and Mg-based systems. In this work magnesium industrial wastes of AZ91 alloy and Mg-10 wt.% Gd alloy are used for the production of hydrogen storage materials. The hydrogen sorption properties of the alloys were investigated by means of volumetric technique, in situ synchrotron radiation powder X-ray diffraction (SR-PXD) and calorimetric methods. The measured reversible hydrogen storage capacity for the alloys AZ91 and Mg-10 wt.% Gd are 4.2 and 5.8 wt.%, respectively. For the Mg-10 wt.% Gd alloy, the hydrogenated product was also successfully used as starting reactant for the synthesis of Mg(NH2)2 and as MgH2 substitute in the Reactive Hydride Composite (RHC) 2LiBH4 + MgH2. The results of this work demonstrate the concrete possibility to use Mg alloy wastes for hydrogen storage purposes.

  6. Glass Formation in Ni-Zr-(Al Alloy Systems

    Directory of Open Access Journals (Sweden)

    Lanping Huang

    2013-01-01

    Full Text Available Structural and thermal properties of binary Ni100-xZrx (30alloys obtained by melt spinning and copper mold casting methods were investigated. The fully amorphous samples in a bulk form cannot be obtained in the binary Ni-Zr alloys over a wide composition range, though they have Tg/Tl and γ values close to or even higher than those of the binary Cu-Zr bulk metallic glasses (BMGs. The low thermal stability of the supercooled liquid against crystallization and the formation of the equilibrium crystalline phases with a high growth rate are responsible for their low glass-forming abilities (GFAs. Relatively low thermal conductivities of Ni-based alloys are also considered to be another factor to limit their GFAs. The GFA of the binary Ni65.5Zr34.5 alloy alloyed with 4% or 5% Al was enhanced, and a fully glassy rod with a diameter of 0.5 mm was formed.

  7. The new Wolf-Rayet binary system WR62a

    Science.gov (United States)

    Collado, A.; Gamen, R.; Barbá, R. H.

    2013-04-01

    Context. A significant number of the Wolf-Rayet stars seem to be binary or multiple systems, but the nature of many of them is still unknown. Dedicated monitoring of WR stars favours the discovery of new systems. Aims: We explore the possibility that WR62a is a binary system. Methods: We analysed the spectra of WR62a, obtained between 2002 and 2010, to look for radial-velocity and spectral variations that would suggest there is a binary component. We searched for periodicities in the measured radial velocities and determined orbital solutions. A period search was also performed on the "All-Sky Automated Survey" photometry. Results: We find that WR62a is a double-lined spectroscopic binary with a WN5 primary star and an O 5.5-6 type secondary component in orbit with a period of 9.1447 d. The minimum masses range between 21 and 23 M⊙ for the WN star and between 39 and 42 M⊙ for the O-type star, thus indicating that the WN star is less massive than the O-type component. We detect a phase shift in the radial-velocity curve of the He ii λ4686 emission line relative to the other emission line curves. The equivalent width of this emission line shows a minimum value when the WN star passes in front of the system. The analysis of the ASAS photometry confirms the spectroscopic periodicity, presenting a minimum at the same phase.

  8. Estimation of the Ideal Binary Mask using Directional Systems

    DEFF Research Database (Denmark)

    Boldt, Jesper; Kjems, Ulrik; Pedersen, Michael Syskind;

    2008-01-01

    and the requirements to enable calculations of the ideal binary mask using a directional system without the availability of the unmixed signals. The proposed method has a low complexity and is verified using computer simulation in both ideal and non-ideal setups showing promising results....

  9. Density-Driven segregation in Binary and Ternary Granular Systems

    NARCIS (Netherlands)

    Windows-Yule, Kit; Parker, David

    2015-01-01

    We present a first experimental study of density-induced segregation within a three-dimensional, vibrofluidised, ternary granular system. Using Positron Emission Particle Tracking (PEPT), we study the steady-state particle distributions achieved by binary and ternary granular beds under a variety of

  10. Friction and wear with a single-crystal abrasive grit of silicon carbide in contact with iron base binary alloys in oil: Effects of alloying element and its content

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1979-01-01

    Sliding friction experiments were conducted with various iron-base binary alloys (alloying elements were Ti, Cr, Mn, Ni, Rh, and W) in contact with a rider of 0.025-millimeter-radius, single-crystal silicon carbide in mineral oil. Results indicate that atomic size and content of alloying element play a dominant role in controlling the abrasive-wear and -friction properties of iron-base binary alloys. The coefficient of friction and groove height (wear volume) general alloy decrease, and the contact pressure increases in solute content. There appears to be very good correlation of the solute to iron atomic radius ratio with the decreasing rate of coefficient of friction, the decreasing rate of groove height (wear volume), and the increasing rate of contact pressure with increasing solute content C. Those rates increase as the solute to iron atomic radius ratio increases from unity.

  11. Inverse problem for the solidification of binary alloy in the casting mould solved by using the bee optimization algorithm

    Science.gov (United States)

    Hetmaniok, Edyta

    2016-07-01

    In this paper the procedure for solving the inverse problem for the binary alloy solidification in the casting mould is presented. Proposed approach is based on the mathematical model suitable for describing the investigated solidification process, the lever arm model describing the macrosegregation process, the finite element method for solving the direct problem and the artificial bee colony algorithm for minimizing the functional expressing the error of approximate solution. Goal of the discussed inverse problem is the reconstruction of heat transfer coefficient and distribution of temperature in investigated region on the basis of known measurements of temperature.

  12. Phase field simulation of the interface morphology evolution and its stability during directional solidification of binary alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The influences of pulling speed V and temperature gradient G on morphology evolution, concentration distribution, solute trapping and interface stability during directional solidification of binary alloys have been studied with the B-S phase field model. Simulated results reproduced the morphology transitions of deep cell to shallow cell and shallow cell to plane front. The primary cellular spacing, depth of groove and effective solute redistribution coefficient for different V and G are compared. The absolute stability under high pulling speed and high temperature gradient has also been predicted, which is in agreement with the Mullins-Sekerka (M-S) stability theory.

  13. Solid solution hardening in face centered binary alloys: Gliding statistics of a dislocation in random solid solution by atomistic simulation

    International Nuclear Information System (INIS)

    The glide of edge and screw dislocation in solid solution is modeled through atomistic simulations in two model alloys of Ni(Al) and Al(Mg) described within the embedded atom method. Our approach is based on the study of the elementary interaction between dislocations and solutes to derive solid solution hardening of face centered cubic binary alloys. We identify the physical origins of the intensity and range of the interaction between a dislocation and a solute atom. The thermally activated crossing of a solute atom by a dislocation is studied at the atomistic scale. We show that hardening of edge and screw segments are similar. We develop a line tension model that reproduces quantitatively the atomistic calculations of the flow stress. We identify the universality class to which the dislocation depinning transition in solid solution belongs. (author)

  14. Improvement of Corrosion Resistance of Binary Mg-Ca Alloys Using Duplex Aluminum-Chromium Coatings

    Science.gov (United States)

    Daroonparvar, Mohammadreza; Yajid, Muhamad Azizi Mat; Yusof, Noordin Mohd; Bakhsheshi-Rad, Hamid Reza; Adabi, Mohsen; Hamzah, Esah; Kamali, Hussein Ali

    2015-07-01

    Al-AlCr was coated on Mg-Ca and Mg-Zn-Ce-La alloys using physical vapor deposition method. The surface morphology of the specimens was characterized by x-ray diffraction, scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and atomic force microscopy (AFM). The AFM results indicated that the average surface roughness of Al-AlCr coating on the Mg-Ca alloy is much lower than that of Al-AlCr coating on the Mg-Zn-Ce-La alloy. However, Al-AlCr coating on the Mg-Ca alloy presented a more compact structure with fewer pores, pinholes, and cracks than Al-AlCr coating on the Mg-Zn-Ce-La alloy. Electrochemical studies revealed that the novel coating (Al-AlCr) can remarkably reduce the corrosion rate of the Mg-Ca alloy in 3.5 wt.% NaCl solution. It was seen that the anodic current density of the Al-AlCr-coated Mg-Ca alloy was very small when compared to the Al-AlCr-coated Mg-Zn-Ce-La and uncoated alloys. Impedance modulus ( Z) of the Al-AlCr-coated samples was higher than that of the bare Mg alloys. Z of Al-AlCr-coated Mg-Ca alloy was higher than that of the Al-AlCr-coated Mg-Zn-Ce-La alloy at low frequency.

  15. Rotational mixing in massive binaries: detached short-period systems

    CERN Document Server

    de Mink, S E; Langer, N; Pols, O R; Brott, I; Yoon, S -Ch

    2009-01-01

    Models of rotating single stars can successfully account for a wide variety of observed stellar phenomena, such as the surface enhancements of N and He. However, recent observations have questioned the idea that rotational mixing is the main process responsible for the surface enhancements, emphasizing the need for a strong and conclusive test. We investigate the consequences of rotational mixing for massive main-sequence stars in short-period binaries. In these systems the tides spin up the stars to rapid rotation. We use a state-of-the-art stellar evolution code including the effect of rotational mixing, tides, and magnetic fields. We discuss the surface abundances expected in massive close binaries (M1~20 solar masses) and we propose using such systems to test the concept of rotational mixing. As these short-period binaries often show eclipses, their parameters can be determined with high accuracy, allowing for a direct comparison with binary evolution models. In more massive close systems (M1~50 solar mas...

  16. The new Wolf-Rayet binary system WR62a

    CERN Document Server

    Collado, A; Barbá, R H

    2013-01-01

    Context. A significant number of the Wolf-Rayet stars seem to be binary or multiple systems, but the nature of many of them is still unknown. Dedicated monitoring of WR stars favours the discovery of new systems. Aims. We explore the possibility that WR62a is a binary system. Methods. We analysed the spectra of WR62a, obtained between 2002 and 2010, to look for radial-velocity and spectral variations that would suggest there is a binary component. We searched for periodicities in the measured radial velocities and determined orbital solutions. A period search was also performed on the "All-Sky Automated Survey" photometry. Results. We find that WR62a is a double-lined spectroscopic binary with a WN5 primary star and an O 5.5-6 type secondary component in orbit with a period of 9.1447 d. The minimum masses range between 21 and 23 Mo for the WN star and between 39 and 42 Mo for the O-type star, thus indicating that the WN star is less massive than the O-type component. We detect a phase shift in the radial-velo...

  17. Physical parameters of components in close binary systems: V

    CERN Document Server

    Zola, S; Zakrzewski, B; Kjurkchieva, D P; Marchev, D V; Baran, A; Rucinski, S M; Ogloza, W; Siwak, M; Koziel, D; Drozdz, M; Pokrzywka, B

    2009-01-01

    The paper presents combined spectroscopic and photometric orbital solutions for ten close binary systems: CN And, V776 Cas, FU Dra, UV Lyn, BB Peg, V592 Per, OU Ser, EQ Tau, HN UMa and HT Vir. The photometric data consist of new multicolor light curves, while the spectroscopy has been recently obtained within the radial velocity program at the David Dunlap Observatory (DDO). Absolute parameters of the components for these binary systems are derived. Our results confirm that CN And is not a contact system. Its configuration is semi-detached with the secondary component filling its Roche lobe. The configuration of nine other systems is contact. Three systems (V776 Cas, V592 Per and OU Ser) have high (44-77%) and six (FU Dra, UV Lyn, BB Peg, EQ Tau, HN UMa and HT Vir) low or intermediate (8-32%) fill-out factors. The absolute physical parameters are derived.

  18. Homologous series of layered structures in binary and ternary Bi-Sb-Te-Se systems: Ab initio study

    Science.gov (United States)

    Govaerts, K.; Sluiter, M. H. F.; Partoens, B.; Lamoen, D.

    2014-02-01

    In order to account explicitly for the existence of long-periodic layered structures and the strong structural relaxations in the most common binary and ternary alloys of the Bi-Sb-Te-Se system, we have developed a one-dimensional cluster expansion (CE) based on first-principles electronic structure calculations, which accounts for the Bi and Sb bilayer formation. Excellent interlayer distances are obtained with a van der Waals density functional. It is shown that a CE solely based on pair interactions is sufficient to provide an accurate description of the ground-state energies of Bi-Sb-Te-Se binary and ternary systems without making the data set of ab initio calculated structures unreasonably large. For the binary alloys A1-xQx (A =Sb, Bi; Q =Te, Se), a ternary CE yields an almost continuous series of (meta)stable structures consisting of consecutive A bilayers next to consecutive A2Q3 for 00.6, the binary alloy segregates into pure Q and A2Q3. The Bi-Sb system is described by a quaternary CE and is found to be an ideal solid solution stabilized by entropic effects at T ≠0 K but with an ordered structure of alternating Bi and Sb layers for x =0.5 at T =0 K. A quintuple CE is used for the ternary Bi-Sb-Te system, where stable ternary layered compounds with an arbitrary stacking of Sb2Te3,Bi2Te3, and Te-Bi-Te-Sb-Te quintuple units are found, optionally separated by mixed Bi/Sb bilayers. Electronic properties of the stable compounds were studied taking spin-orbit coupling into account.

  19. Planetary Dynamics and Habitable Planet Formation In Binary Star Systems

    CERN Document Server

    Haghighipour, Nader; Pilat-Lohinger, Elke

    2009-01-01

    Whether binaries can harbor potentially habitable planets depends on several factors including the physical properties and the orbital characteristics of the binary system. While the former determines the location of the habitable zone (HZ), the latter affects the dynamics of the material from which terrestrial planets are formed (i.e., planetesimals and planetary embryos), and drives the final architecture of the planets assembly. In order for a habitable planet to form in a binary star system, these two factors have to work in harmony. That is, the orbital dynamics of the two stars and their interactions with the planet-forming material have to allow terrestrial planet formation in the habitable zone, and ensure that the orbit of a potentially habitable planet will be stable for long times. We have organized this chapter with the same order in mind. We begin by presenting a general discussion on the motion of planets in binary stars and their stability. We then discuss the stability of terrestrial planets, ...

  20. Magnetostriction of heavily deformed Fe–Co binary alloys prepared by forging and cold rolling

    Energy Technology Data Exchange (ETDEWEB)

    Yamaura, Shin-ichi, E-mail: yamaura@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan); Nakajima, Takashi [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan); Satoh, Takenobu; Ebata, Takashi [Tohoku Steel, Co., Ltd., 23 Nishigaoka, Murata, Murata-machi, Shibata 989-1393 (Japan); Furuya, Yasubumi [North Japan Research Institute for Sustainable Energy, Hirosaki University, 2-1-3 Matsubara, Aomori 030-0813 (Japan)

    2015-03-15

    Highlights: • The as-forged Fe{sub 25}Co{sub 75} alloy shows the magnetostriction of 108 ppm. • The as-cold rolled Fe{sub 25}Co{sub 75} alloy shows the magnetostriction of 140 ppm. • Magnetostriction of Fe–Co alloy reached the maximum in a single bcc state. • Fcc phase is harmful to the increase in magnetostriction of Fe–Co alloy. • Fcc phase precipitation in Fe–Co alloy can be suppressed by cold rolling. - Abstract: Magnetostriction of Fe{sub 1−x}Co{sub x} (x = 50–90 at%) alloys prepared by forging and subsequent cold-rolling was studied as functions of alloy compositions and thermomechanical treatments. Magnetostriction of the as-forged Fe{sub 25}Co{sub 75} alloy was 108 ppm and that of the as-cold rolled Fe{sub 25}Co{sub 75} alloy measured parallel to the rolling direction (RD) was 128 ppm. The cold-rolled Fe{sub 25}Co{sub 75} alloy possessed a nearly {1 0 0}<0 1 1> texture, leading to the maximum magnetostriction of 140 ppm when measured at an angle of 45° to RD. Moreover, the fully annealed Fe{sub 25}Co{sub 75} and Fe{sub 20}Co{sub 80} alloys were gradually cold rolled and magnetostriction were measured. Results showed that the magnetostriction of those cold-rolled alloys drastically increased with increasing reduction rate. According to the XRD and TEM observations, intensity of the fcc peak gradually decreased with increasing reduction rate and that the alloys became to be in a bcc single state at a reduction rate higher than 90%, leading to a drastic increase in magnetostriction.

  1. The friction and wear of metals and binary alloys in contact with an abrasive grit of single-crystal silicon carbide

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1979-01-01

    Sliding friction experiments were conducted with various metals and iron-base binary alloys (alloying elements Ti, Cr, Mn, Ni, Rh, and W) in contact with single-crystal silicon carbide riders. Results indicate that the coefficient of friction and groove height (corresponding to the wear volume) decrease linearly as the shear strength of the bulk metal increases. The coefficient of friction and groove height generally decrease with an increase in solute content of binary alloys. A separate correlation exists between the solute to iron atomic radius ratio and the decreasing rates of change of coefficient of friction and groove height with increasing solute content. These rates of change are minimum at a solute to iron radius ratio of unity. They increase as the atomic ratio increases or decreases linearly from unity. The correlations indicate that atomic size is an important parameter in controlling friction and wear of alloys.

  2. Simulating the Effect of Space Vehicle Environments on Directional Solidification of a Binary Alloy

    Science.gov (United States)

    Westra, D. G.; Heinrich, J. C.; Poirier, D. R.

    2003-01-01

    Space microgravity missions are designed to provide a microgravity environment for scientific experiments, but these missions cannot provide a perfect environment, due to vibrations caused by crew activity, on-board experiments, support systems (pumps, fans, etc.), periodic orbital maneuvers, and water dumps. Therefore, it is necessary to predict the impact of these vibrations on space experiments, prior to performing them. Simulations were conducted to study the effect of the vibrations on the directional solidification of a dendritic alloy. Finite element ca!cu!attie?ls were dme with a simd2titcr based on a continuum model of dendritic solidification, using the Fractional Step Method (FSM). The FSM splits the solution of the momentum equation into two steps: the viscous intermediate step, which does not enforce continuity; and the inviscid projection step, which calculates the pressure and enforces continuity. The FSM provides significant computational benefits for predicting flows in a directionally solidified alloy, compared to other methods presently employed, because of the efficiency gains in the uncoupled solution of velocity and pressure. finite differences, arises when the interdendritic liquid reaches the eutectic temperature and concentration. When a node reaches eutectic temperature, it is assumed that the solidification of the eutectic liquid continues at constant temperature until all the eutectic is solidified. With this approach, solidification is not achieved continuously across an element; rather, the element is not considered solidified until the eutectic isotherm overtakes the top nodes. For microgravity simulations, where the convection is driven by shrinkage, it introduces large variations in the fluid velocity. When the eutectic isotherm reaches a node, all the eutectic must be solidified in a short period, causing an abrupt increase in velocity. To overcome this difficulty, we employed a scheme to numerically predict a more accurate value

  3. A general scheme for the estimation of oxygen binding energies on binary transition metal surface alloys

    DEFF Research Database (Denmark)

    Greeley, Jeffrey Philip; Nørskov, Jens Kehlet

    2005-01-01

    A simple scheme for the estimation of oxygen binding energies on transition metal surface alloys is presented. It is shown that a d-band center model of the alloy surfaces is a convenient and appropriate basis for this scheme; variations in chemical composition, strain effects, and ligand effects...... for the estimation of oxygen binding energies on a wide variety of transition metal alloys. (c) 2005 Elsevier B.V. All rights reserved....

  4. Binary Systems as Resonance Detectors for Gravitational Waves

    CERN Document Server

    Hui, Lam; Yang, I-Sheng

    2012-01-01

    Gravitational waves at suitable frequencies can resonantly interact with a binary system, inducing changes to its orbit. A stochastic gravitational-wave background causes the orbital elements of the binary to execute a classic random walk -- with the variance of orbital elements growing with time. The lack of such a random walk in binaries that have been monitored with high precision over long time-scales can thus be used to place an upper bound on the gravitational-wave background. Using periastron time data from the Hulse-Taylor binary pulsar spanning ~30 years, we obtain a bound of h_c < 7.9 x 10^-14 at ~10^-4 Hz, where h_c is the strain amplitude per logarithmic frequency interval. Our constraint complements those from pulsar timing arrays, which probe much lower frequencies, and ground-based gravitational-wave observations, which probe much higher frequencies. Interesting sources in our frequency band, which overlaps the lower sensitive frequencies of proposed space-based observatories, include white-...

  5. Thermodynamic assessment of the dysprosium–gold binary system

    Energy Technology Data Exchange (ETDEWEB)

    Otmani, Samira, E-mail: samira.otmani@edu.uiz.ac.ma; Mahdouk, Kamal

    2015-11-05

    Phase relationships in Dy–Au binary system has been thermodynamically assessed by using the CALPHAD technique. Liquid and the solution phases, fcc-A1, bcc-A2 and hcp-A3, were treated as a substitutional solution model. The binary intermetallic compounds are treated as stoichiometric phases. All the thermodynamic parameters of various phases have been optimized and the calculated results are confronted with experimental data. - Highlights: • Rare earth elements are increasingly used in advanced materials. • To our knowledge, this system was not previously optimized. • A consistent set of thermodynamic parameters was optimized. • This work is the start point for the study of ternary systems with RE.

  6. Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys

    International Nuclear Information System (INIS)

    Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T0 curves, which makes Al-Si a good candidate for solubility extension while the plunging T0 line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 (micro)m with a Peclet number of ∼0.2, JH and TMK deviate from each other. This

  7. Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kalay, Yunus Eren [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T0 curves, which makes Al-Si a good candidate for solubility extension while the plunging T0 line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 {micro}m with a Peclet number of ~0.2, JH and TMK deviate from

  8. In situ determination of binary alloy melt compositions in the LHDAC by X- Radiography

    Science.gov (United States)

    Lord, O. T.; Walter, M. J.; Walker, D.; Clark, S. M.

    2008-12-01

    Constraining the light element in Earth's molten outer core requires an understanding of the melting phase relations in iron-light element binary systems. For example, it is critical to determine the composition of liquids at binary eutectics. Typically such measurements are carried out after the sample has been quenched in temperature and pressure. Such 'cook and look' methods possibly suffer from systematic errors introduced by exsolution of the light element from the melt on quench and error in the reintegration of the liquid composition [1]. Here, we present a novel method for the determination of melt compositions in iron-light element binary systems in situ in the LHDAC at simultaneous high-pressure, high-temperature conditions. Samples consist of a light element bearing compound, such as FeO, surrounded by a pure iron ring, forming a donut ~100 μm in diameter and ~15 μm thick. The donuts are loaded into stainless steel gaskets in the DAC, sandwiched between discs fabricated from sol-gel deposited nanocrystalline Al2O3 with similar dimensions to the donut. Pressure is monitored by ruby fluorescence during compression. The sample is heated at the boundary between the iron and light element compound using two 100 W IR lasers in a double-sided configuration at beamline 12.2.2 at the Advanced Light Source. Temperature is measured by spectroradiometry. Before, during and after melting, X-radiographic images of the sample are taken by shining a defocused beam of synchrotron X-rays through the sample and onto a CdWO4 phosphor. The visible light from the phosphor is then focused onto a high resolution CCD, where absorption contrast images are recorded. The absorption of the molten region is then determined, and it's composition calculated by linear interpolation between the absorption of the two solid end members. As a test of the reliability of the method we measured the Fe-FeS eutectic to 20 GPa and our results are in good agreement with previous studies that are

  9. Deep, Low Mass Ratio Overcontact Binary Systems. XIV. A Statistical Analysis of 46 Sample Binaries

    Science.gov (United States)

    Yang, Yuan-Gui; Qian, Sheng-Bang

    2015-09-01

    A sample of 46 deep, low mass ratio (DLMR) overcontact binaries (i.e., q≤slant 0.25 and f≥slant 50%) is statistically analyzed in this paper. It is found that five relations possibly exist among some physical parameters. The primary components are little-evolved main sequence stars that lie between the zero-age main sequence line and the terminal-age main sequence (TAMS) line. Meanwhile, the secondary components may be evolved stars above the TAMS line. The super-luminosities and large radii may result from energy transfer, which causes their volumes to expand. The equations of M-L and M-R for the components are also determined. The relation of P-Mtotal implies that mass may escape from the central system when the orbital period decreases. The minimum mass ratio may preliminarily be {q}{min}=0.044(+/- 0.007) from the relations of q-f and q-Jspin/Jorb. With mass and angular momentum loss, the orbital period decreases, which finally causes this kind of DLMR overcontact binary to merge into a rapid-rotating single star.

  10. Excess Molar Volume of Binary Systems Containing Mesitylene

    Directory of Open Access Journals (Sweden)

    Morávková, L.

    2013-05-01

    Full Text Available This paper presents a review of density measurements for binary systems containing 1,3,5-trimethylbenzene (mesitylene with a variety of organic compounds at atmospheric pressure. Literature data of the binary systems were divided into nine basic groups by the type of contained organic compound with mesitylene. The excess molar volumes calculated from the experimental density values have been compared with literature data. Densities were measured by a few experimental methods, namely using a pycnometer, a dilatometer or a commercial apparatus. The overview of the experimental data and shape of the excess molar volume curve versus mole fraction is presented in this paper. The excess molar volumes were correlated by Redlich–Kister equation. The standard deviations for fitting of excess molar volume versus mole fraction are compared. Found literature data cover a huge temperature range from (288.15 to 343.15 K.

  11. Heats of Mixing in Binary Systems of Molten Salts

    International Nuclear Information System (INIS)

    The heat of mixing is an important thermodynamic property in binary mixtures. As a result of the recent development of high-temperature calorimetry we have been able to determine directly the heat of mixing in binary systems of molten salts. In this work we present the results of thermochemical measurements carried out in our laboratories for the systems (Rb-K)Cl; (Rb-Na)Cl; (Ag-Na)Cl; (Na-K)Br and(Br-Cl)Na for different concentrations and temperatures. In our view, the most significant components of the heat of mixing are the ionic contribution and the polarization energy of the ions. Consequently, use could be made of a relation of the form: ΔHM = Qi - Qp. The heat of mixing can then have either positive or negative values depending on the sign and the preponderance of the Qi and Qp energies. (author)

  12. Be discs in binary systems I. Coplanar orbits

    CERN Document Server

    Panoglou, Despina; Vieira, Rodrigo G; Cyr, Isabelle H; Jones, Carol E; Okazaki, Atsuo T; Rivinius, Thomas

    2016-01-01

    Be stars are surrounded by outflowing circumstellar matter structured in the form of decretion discs. They are often members of binary systems, where it is expected that the decretion disc interacts both radiatively and gravitationally with the companion. In this work we study how various orbital (period, mass ratio, eccentricity) and disc (viscosity) parameters affect the disc structure in coplanar systems. We simulate such binaries with the use of a smoothed particle hydrodynamics code. The main effects of the secondary on the disc are its truncation and the accumulation of material inwards of truncation. In circular or nearly circular prograde orbits, the disc maintains a rotating, constant in shape, configuration, which is locked to the orbital phase. The disc is smaller in size, more elongated and more massive for low viscosity parameter, small orbital separation and/or high mass ratio. Highly eccentric orbits are more complex, with the disc structure and total mass strongly dependent on the orbital phas...

  13. Influence of solutes on heavy ion induced void-swelling in binary copper alloys

    International Nuclear Information System (INIS)

    As radiation induced swelling of metals depends on their constitution, swelling of copper and copper alloys with low solute concentration is studied. Diffusion coefficients and solubility of solute in copper were used as criteria of selection of the alloys. The samples were irradiated by 200keV copper ions. Swelling and void densities were measured by transmission electron microscopy. The measurements show low dependence of swelling upon the diffusibility of the solute in the solvent and a strong dependence on their concentration. Alloys of 0.1at% solute show more swelling than pure copper, and alloys of 1at% show less swelling under the irradiation conditions. The different swelling behavior in Cu-Ni alloys is due to the different void densities. (orig.)

  14. Ordered Structures of a Binary Mixture with Mobile Particles System

    Institute of Scientific and Technical Information of China (English)

    诸跃进; 马余强

    2003-01-01

    We study the ordered structures of a binary mixture through the introduction of mobile particles under periodically oscillating driving fields, and find that the particle motion can break up the isotropy of the system, so that the continuous structure along the oscillation forcing direction is observed for properly chosen oscillating field.Furthermore, the dependences of the morphology and domain size on the mixture-particle coupling interaction,the diffusion coefficient, and the quench depth are examined in details.

  15. Benchmark ultra-cool dwarfs in widely separated binary systems

    Directory of Open Access Journals (Sweden)

    Jones H.R.A.

    2011-07-01

    Full Text Available Ultra-cool dwarfs as wide companions to subgiants, giants, white dwarfs and main sequence stars can be very good benchmark objects, for which we can infer physical properties with minimal reference to theoretical models, through association with the primary stars. We have searched for benchmark ultra-cool dwarfs in widely separated binary systems using SDSS, UKIDSS, and 2MASS. We then estimate spectral types using SDSS spectroscopy and multi-band colors, place constraints on distance, and perform proper motions calculations for all candidates which have sufficient epoch baseline coverage. Analysis of the proper motion and distance constraints show that eight of our ultra-cool dwarfs are members of widely separated binary systems. Another L3.5 dwarf, SDSS 0832, is shown to be a companion to the bright K3 giant η Cancri. Such primaries can provide age and metallicity constraints for any companion objects, yielding excellent benchmark objects. This is the first wide ultra-cool dwarf + giant binary system identified.

  16. A model of the subdwarf binary system LB 3459

    International Nuclear Information System (INIS)

    A model is presented for a short period eclipsing binary LB 3459 (=CPD-60deg389=HDE 269696). The primary of 0,36 Msub(sun) and effective temperature of 64000 K burns hydrogen in a shell source surrounding a degenerate helium core. The secondary of 0,054 Msub(sun) is nearly degenerate, and probably hydrogen rich star. The hemisphere facing the primary is heated to 20000 K. The system had the initial orbital period of about 3 months, and evolved through a common envelope phase. When the orbital period was reduced to the present value of 6 hours the common envelope was lost some 5.105 years ago. At that time the system might look like UU Sge, an eclipsing binary nucleus of a planetary nebula. In another 5.105 years the primary will become a hot degenerate dwarf and the system will look like an eclipsing binary PG 1413+01. In about 5.1010 years the orbital period will decrease to 38 minutes as a result of gravitational radiation. At that time the degenerate, hydrogen rich secondary will overflow its Roche lobe and LB 3459 will become a cataclysmic variable. (author)

  17. Microstructural and mechanical properties of binary Ni–Si eutectic alloys

    International Nuclear Information System (INIS)

    Highlights: • Ni80Si20, Ni70Si30, Ni55Si45 and Ni45Si55 were prepared by arc melting method. • The maximum microhardness value of 1126 HV obtained for Ni70Si30 alloy. • The microhardness values decreases with increase of Si/Ni ratio. • Ni80Si20 and Ni55Si45 are soft ferromagnetic, Ni70Si30 and Ni45Si55 are paramagnetic. - Abstract: In the present work, Ni–Si eutectic alloys with nominal compositions of Ni80Si20, Ni70Si30, Ni55Si45 and Ni45Si55 (Ni and Si with the purity of 99.99%) were prepared by arc melting method under vacuum/argon atmosphere. The effects of Si/Ni ratio on the microstructural properties, thermal transformation behavior, micro-hardness and magnetic properties of the Ni–Si eutectic alloys were investigated. These alloys were characterized by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), differential thermal analysis (DTA), Vickers microhardness measurement and Vibrating Sample Magnetometer (VSM). The phases expected according to Ni–Si phase diagram for conventional solidified eutectic Ni–Si alloys are considerably consistent with phase detected by XRD in this study. The quantitative results confirm that the chemical composition of the alloys very close to eutectic compositions and the microstructures are in typical lamellar eutectic morphology. The maximum microhardness value of 1126 HV obtained for Ni70Si30 alloy which has highest melting temperature amongst Ni–Si eutectics. The microhardness values decreases with increase of Si/Ni ratio. Ni80Si20 and Ni55Si45 alloys are soft ferromagnetic, Ni70Si30 and Ni45Si55 alloys are paramagnetic with no magnetic saturation

  18. MICRO-DESCRIPTION OF THE SOLUTE-FIELD AND THE PHASE-FIELD MODEL FOR ISOTHERMAL PHASE TRANSITION IN BINARY ALLOYS

    Institute of Scientific and Technical Information of China (English)

    H.M. Ding; L.L. Chen; R.X. Liu

    2004-01-01

    A new phase field method for two-dimensional simulations of binary alloy solidification was studied. A model basing on solute conservative in every unit was developed for solving the solute diffusion equation during solidification. Two-dimensional computations were performed for ideal solutions and Ni-Cu dendritic growth into an isothermal and highly supersaturated liquid phase.

  19. Ab initio study of the magnetic configurations on the (0 0 1) surfaces of binary FePd and FeRh ordered alloys

    NARCIS (Netherlands)

    Dahmoune, C.; Lounis, S.; Talanana, M.; Benakki, M.; Bouarab, S.; Demangeat, C.

    2002-01-01

    Ab initio calculations of the local spin polarization at the (0 0 1) surfaces performed on the binary FePd and FeRh alloys are presented. For Rh-terminated FeRh (0 0 1) surface, the calculations indicate a possible magnetic reconstruction leading to a ferromagnetic order in the surface region, in co

  20. Searching Planets Around Some Selected Eclipsing Close Binary Stars Systems

    Science.gov (United States)

    Nasiroglu, Ilham; Slowikowska, Agnieszka; Krzeszowski, Krzysztof; Zejmo, M. Michal; Er, Hüseyin; Goździewski, Krzysztof; Zola, Stanislaw; Koziel-Wierzbowska, Dorota; Debski, Bartholomew; Ogloza, Waldemar; Drozdz, Marek

    2016-07-01

    We present updated O-C diagrams of selected short period eclipsing binaries observed since 2009 with the T100 Telescope at the TUBITAK National Observatory (Antalya, Turkey), the T60 Telescope at the Adiyaman University Observatory (Adiyaman, Turkey), the 60cm at the Mt. Suhora Observatory of the Pedagogical University (Poland) and the 50cm Cassegrain telescope at the Fort Skala Astronomical Observatory of the Jagiellonian University in Krakow, Poland. All four telescopes are equipped with sensitive, back-illuminated CCD cameras and sets of wide band filters. One of the targets in our sample is a post-common envelope eclipsing binary NSVS 14256825. We collected more than 50 new eclipses for this system that together with the literature data gives more than 120 eclipse timings over the time span of 8.5 years. The obtained O-C diagram shows quasi-periodic variations that can be well explained by the existence of the third body on Jupiter-like orbit. We also present new results indicating a possible light time travel effect inferred from the O-C diagrams of two other binary systems: HU Aqr and V470 Cam.

  1. Self Regulated Shocks in Massive Star Binary Systems

    CERN Document Server

    Parkin, E R

    2013-01-01

    In an early-type, massive star binary system, X-ray bright shocks result from the powerful collision of stellar winds driven by radiation pressure on spectral line transitions. We examine the influence of the X-rays from the wind-wind collision shocks on the radiative driving of the stellar winds using steady state models that include a parameterized line force with X-ray ionization dependence. Our primary result is that X-ray radiation from the shocks inhibits wind acceleration and can lead to a lower pre-shock velocity, and a correspondingly lower shocked plasma temperature, yet the intrinsic X-ray luminosity of the shocks, LX remains largely unaltered, with the exception of a modest increase at small binary separations. Due to the feedback loop between the ionizing X-rays from the shocks and the wind-driving, we term this scenario as self regulated shocks. This effect is found to greatly increase the range of binary separations at which a wind-photosphere collision is likely to occur in systems where the m...

  2. Nature of dissolution of binary tantalum-titanium alloys by molten plutonium

    International Nuclear Information System (INIS)

    Tantalum hardware has often been used for the processing of molten Pu where ceramics are inappropriate. However, there has only been limited work on the containment of Pu by Ta alloys. In this regard, the authors have investigated the interaction of Ta-Ti alloys (20, 40 and 60 wt.% Ti) with molten Pu at 850 and 1,000 C. The microstructures of Pu/alloy interfaces were characterized chemically and metallographically following various exposures to liquid Pu. Dissolution does not proceed uniformly, but appears to initiate by intergranular attack to a shallow depth and then progress by the formation of a stable mushy zone at the liquid/solid interface. The resistance to dissolution by molten Pu increases with the Ta content of the alloy

  3. Amorphous Formation in an Undercooled Binary Ni-Si Alloy under Slow Cooling Rate

    Institute of Scientific and Technical Information of China (English)

    Yiping Lu; Gencang Yang; Xiong Li; Yaohe Zhou

    2009-01-01

    High undercooling up to 392 K was achieved in eutectic Ni70.2Si29.8 alloy melt by using glass fluxing combined with cyclic superheating.A small quantity of amorphous phase was obtained in bulk eutectic Ni70.2Si29.8 alloy when undercooling exceeds 240 K under slow cooling conditions (about 1 K/s).The amorphous phase was confirmed by high-resolution transmission electron microscopy and differential scanning calorimetry.

  4. Simulation of the Effect of Realistic Space Vehicle Environments on Binary Metal Alloys

    Science.gov (United States)

    Westra, Douglas G.; Poirier, D. R.; Heinrich, J. C.; Sung, P. K.; Felicelli, S. D.; Phelps, Lisa (Technical Monitor)

    2001-01-01

    Simulations that assess the effect of space vehicle acceleration environments on the solidification of Pb-Sb alloys are reported. Space microgravity missions are designed to provide a near zero-g acceleration environment for various types of scientific experiments. Realistically. these space missions cannot provide a perfect environment. Vibrations caused by crew activity, on-board experiments, support systems stems (pumps, fans, etc.), periodic orbital maneuvers, and water dumps can all cause perturbations to the microgravity environment. In addition, the drag on the space vehicle is a source of acceleration. Therefore, it is necessary to predict the impact of these vibration-perturbations and the steady-state drag acceleration on the experiments. These predictions can be used to design mission timelines. so that the experiment is run during times that the impact of the acceleration environment is acceptable for the experiment of interest. The simulations reported herein were conducted using a finite element model that includes mass, species, momentum, and energy conservation. This model predicts the existence of "channels" within the processing mushy zone and subsequently "freckles" within the fully processed solid, which are the effects of thermosolutal convection. It is necessary to mitigate thermosolutal convection during space experiments of metal alloys, in order to study and characterize diffusion-controlled transport phenomena (microsegregation) that are normally coupled with macrosegregation. The model allows simulation of steady-state and transient acceleration values ranging from no acceleration (0 g). to microgravity conditions (10(exp -6) to 10(exp -3) g), to terrestrial gravity conditions (1 g). The transient acceleration environments simulated were from the STS-89 SpaceHAB mission and from the STS-94 SpaceLAB mission. with on-orbit accelerometer data during different mission periods used as inputs for the simulation model. Periods of crew exercise

  5. Short-range order types in binary alloys: A reflection of coherent phase stability

    Energy Technology Data Exchange (ETDEWEB)

    W. Wolverton; V. Ozolins; Alex Zunger

    1999-11-23

    The short-range order (SRO) present in disordered solid solutions is classified according to three characteristic system-dependent energies: (1) formation enthalpies of ordered compounds, (2) enthalpies of mixing of disordered alloys, and (3) the energy of coherent phase separation, (the composition-weighted energy of the constituents each constrained to maintain a common lattice constant along an A/B interface). These energies are all compared against a common reference, the energy of incoherent phase separation (the composition-weighted energy of the constituents each at their own equilibrium volumes). Unlike long-range order (LRO), short-range order is determined by energetic competition between phases at a fixed composition, and hence only coherent phase-separated states are of relevance for SRO. The authors find five distinct SRO types, and show examples of each of these five types, including Cu-Au, Al-Mg, GaP-InP, Ni-Au, and Cu-Ag. The SRO is calculated from first-principles using the mixed-space cluster expansion approach combined with Monte Carlo simulations. Additionally, they examine the effect of inclusion of coherency strain in the calculation of SRO, and specifically examine the appropriate functional form for accurate SRO calculations.

  6. Measurement of VLE data for binary lipids systems

    DEFF Research Database (Denmark)

    Cunico, Larissa; Ceriani, Roberta; Sarup, Bent;

    components and also for their mixtures. To contribute in this area, experimental data were obtained using the Differential Scanning Calorimetry (DSC) technique for isobaric vapor-liquid equilibrium (VLE) of two binary mixtures at two different pressures (1.2 and 2.5 KPa): system 1 [monoacylglycerol...... is revealed for both systems at the two different pressures, with azeotrope behavior observed and confirmed but the relative volatility analysis. Available thermodynamic consistency tests for TPx data were applied before performing parameter regressions for Wilson NRTL, UNIQUAC and original UNIFAC models...

  7. Microstructure, Elastic Modulus and Tensile Properties of Ti-Nb-O Alloy System

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In the present study Ti-Nb binary alloy system was chosen because it has excellent biocompatibility as well as reasonable mechanical properties, aiming at understanding oxygen content on microstructural formation,elastic modulus and tensile properties in Ti-Nb alloy system. Small alloy buttons of 50 mm in diameter were prepared by arc melting on a water-cooled copper hearth under an argon gas atmosphere with a non-consumable tungsten electrode. The button ingots were then heat treated in a vacuum atmosphere at 1273 K for 0.5 h followed by water quenching in a specially designed heat treatment furnace. Microstructure, elastic modulus and tensile properties were investigated in order to understand the effect of oxygen content in quenched TiNb alloy system. The orthorhombic structured α″ martensite was changed to bcc structured β-phase with increasing Nb content. Interestingly, it was found that oxygen makes β-phase stable in quenched Ti-Nb alloy system. Elastic modulus values were sensitive to phase stability of constituent phases. Yield strength increased with increasing oxygen content. Details will be explained by phase formation and stability behavior.

  8. The visually close binary system HD375; Is it a sub-giant binary?

    CERN Document Server

    Al-Wardat, M A; Leushion, V V; Taani, A A; Yusuf, N A; Al-Waqfi, K S; Masda, S

    2013-01-01

    Atmospheric modeling is used to build synthetic spectral energy distributions (SEDs) for the individual components of the speckle interferometric binary system HD375. These synthetic SEDs are combined together for the entire system and compared with its observational SED in an iterated procedure to achieve the best fit. Kurucz blanketed models with the measurements of magnitude differences were used to build these SED's. The input physical elements for building these best fitted synthetic SEDs represent adequately enough the elements of the system. These elements are: $T_{\\rm eff}^{a} =6100\\pm50$\\,K, $T_{\\rm eff}^{b} =5940\\pm50$\\,K, log $g_{a}=4.01\\pm0.10$, log $g_{b}=3.98\\pm0.10$, $R_a=1.93\\pm0.20 R_\\odot$, $R_b=1.83\\pm0.20 R_\\odot$ $M_{v}^{\\rm a}=3.26\\pm0.40$, $M_{v}^{\\rm b}=3.51\\pm0.50$, $L_a= 4.63\\pm0.80 L_\\odot$ and $ L_b= 3.74\\pm0.70 L_\\odot$ depending on new estimated parallax $\\pi=12.02 \\pm 0.60$ mas. A modified orbit of the system is built and compared with earlier orbits and the masses of the two co...

  9. Effects of temperature boundary conditions on equiaxed dendritic growth in phase-field simulations of binary alloy

    Institute of Scientific and Technical Information of China (English)

    于艳梅; 杨根仓; 赵达文; 吕衣礼

    2002-01-01

    By the phase-field approach, the dendritic growth in binary alloy melt was simulated respectively using two types of temperature boundary conditions, i.e., the constant temperature boundary by which the boundary temperature was fixed at the initial temperature, and Zero-Neumann temperature boundary. The influences of the temperature boundary conditions on numerical results are investigated. How to choose appropriate temperature boundary conditions is proposed. The results show that: 1) when the computation region is limited to a changeless size, the Zero-Neumann and constant temperature boundary conditions lead to the different dendritic growth behaviors, and the Zero-Neumann condition is preferable to the constant temperature condition; 2) when the computation region is enlarged continually with the computational time according to the increasing thermal diffusion scale, the two types of temperature boundary conditions achieve the consistent tip velocities and tip radii, and they both are appropriate choices.

  10. Two-dimensional phase-field study of competitive grain growth during directional solidification of polycrystalline binary alloy

    Science.gov (United States)

    Takaki, Tomohiro; Ohno, Munekazu; Shibuta, Yasushi; Sakane, Shinji; Shimokawabe, Takashi; Aoki, Takayuki

    2016-05-01

    Selections of growing crystals during directional solidification of a polycrystalline binary alloy were numerically investigated using two-dimensional phase-field simulations. To accelerate the simulations, parallel graphics processing unit (GPU) simulations were performed using the GPU-rich supercomputer TSUBAME2.5 at the Tokyo Institute of Technology. Twenty simulations with a combination of five sets of different seed orientation distributions and four different temperature gradients covering dendritic and cellular growth regions were performed. The unusual grain selection phenomenon, in which the unfavorably oriented grains preferentially grow instead of the favorably oriented grains, was observed frequently. The unusual selection was more remarkable in the cellular structure than in the dendritic structure.

  11. A systematic study of segregation for Zn{sub x}Bi{sub 1−x} liquid binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kasem, Md. Riad; Maruf, Md. Helal Uddin [Department of Physics, University of Dhaka, Dhaka (Bangladesh); Bhuiyan, G. M., E-mail: gbhuiyan@du.ac.bd [Department of Theoretical Physics, University of Dhaka, Dhaka (Bangladesh)

    2015-07-21

    We have investigated the segregating properties of Zn{sub x}Bi{sub 1−x} liquid binary alloys through the thermodynamic route that involves both energy of mixing and entropy of mixing. The perturbation approach is used for effective numerical calculations. Results of our calculations agree well with corresponding experimental data for energy and entropy of mixing in the mixed state. The final prediction of segregating properties such as critical concentration and critical temperature also matches reasonably well with experimental data. Most importantly, both energy of mixing and entropy of mixing have produced almost same values for critical concentration and critical temperature of segregation and thus confirm the reliability of the present approach.

  12. Investigations of multiple scattering of 662 keV gamma photons in binary alloys - an inverse response matrix approach

    International Nuclear Information System (INIS)

    The present measurements are carried out to investigate the multiple scattering of 662 keV gamma photons emerging from targets of binary alloys (soldering material and brass). The scattered photons are detected by a 51 mm x 51 mm NaI(Tl) scintillation detector whose response unscrambling, converting the observed pulse-height distribution to a true photon energy spectrum, is obtained with the help of a 10x10 inverse response matrix. The full energy peak corresponding to singly scattered events is reconstructed analytically. We observe that the numbers of multiple scattered events, having same energy as in the singly scattered distribution, first increases with increase in target thickness and then saturate. The application of response function of the scintillation detector does not result in any change of measured saturation thickness. Monte Carlo calculations support the present experimental results. (author)

  13. Microstructural and mechanical properties of binary Ni–Si eutectic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gogebakan, Musa, E-mail: gogebakan@ksu.edu.tr [Department of Physics, Faculty of Art and Sciences, Kahramanmaras Sutcu Imam University, Kahramanmaras 46100 (Turkey); Kursun, Celal [Department of Physics, Faculty of Art and Sciences, Kahramanmaras Sutcu Imam University, Kahramanmaras 46100 (Turkey); Gunduz, Kerem Ozgur; Tarakci, Mehmet; Gencer, Yucel [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, 41400 Kocaeli (Turkey)

    2015-09-15

    Highlights: • Ni{sub 80}Si{sub 20}, Ni{sub 70}Si{sub 30}, Ni{sub 55}Si{sub 45} and Ni{sub 45}Si{sub 55} were prepared by arc melting method. • The maximum microhardness value of 1126 HV obtained for Ni{sub 70}Si{sub 30} alloy. • The microhardness values decreases with increase of Si/Ni ratio. • Ni{sub 80}Si{sub 20} and Ni{sub 55}Si{sub 45} are soft ferromagnetic, Ni{sub 70}Si{sub 30} and Ni{sub 45}Si{sub 55} are paramagnetic. - Abstract: In the present work, Ni–Si eutectic alloys with nominal compositions of Ni{sub 80}Si{sub 20}, Ni{sub 70}Si{sub 30}, Ni{sub 55}Si{sub 45} and Ni{sub 45}Si{sub 55} (Ni and Si with the purity of 99.99%) were prepared by arc melting method under vacuum/argon atmosphere. The effects of Si/Ni ratio on the microstructural properties, thermal transformation behavior, micro-hardness and magnetic properties of the Ni–Si eutectic alloys were investigated. These alloys were characterized by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), differential thermal analysis (DTA), Vickers microhardness measurement and Vibrating Sample Magnetometer (VSM). The phases expected according to Ni–Si phase diagram for conventional solidified eutectic Ni–Si alloys are considerably consistent with phase detected by XRD in this study. The quantitative results confirm that the chemical composition of the alloys very close to eutectic compositions and the microstructures are in typical lamellar eutectic morphology. The maximum microhardness value of 1126 HV obtained for Ni{sub 70}Si{sub 30} alloy which has highest melting temperature amongst Ni–Si eutectics. The microhardness values decreases with increase of Si/Ni ratio. Ni{sub 80}Si{sub 20} and Ni{sub 55}Si{sub 45} alloys are soft ferromagnetic, Ni{sub 70}Si{sub 30} and Ni{sub 45}Si{sub 55} alloys are paramagnetic with no magnetic saturation.

  14. Carrying a Torch for Dust in Binary Star Systems

    CERN Document Server

    Cotton, Daniel V; Bott, Kimberly; Kedziora-Chudczer, Lucyna; Bailey, Jeremy

    2016-01-01

    Young stars are frequently observed to host circumstellar disks, within which their attendant planetary systems are formed. Scattered light imaging of these proto-planetary disks reveals a rich variety of structures including spirals, gaps and clumps. Self-consistent modelling of both imaging and multi-wavelength photometry enables the best interpretation of the location and size distribution of disks' dust. Epsilon Sagittarii is an unusual star system. It is a binary system with a B9.5III primary that is also believed to host a debris disk in an unstable configuration. Recent polarimetric measurements of the system with the High Precision Polarimetric Instrument (HIPPI) revealed an unexpectedly high fractional linear polarisation, one greater than the fractional infrared excess of the system. Here we develop a spectral energy distribution model for the system and use this as a basis for radiative transfer modelling of its polarisation with the RADMC-3D software package. The measured polarisation can be repro...

  15. Electron–phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    International Nuclear Information System (INIS)

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration. (paper)

  16. Microstructure formation in binary Al-TM alloys under non-equilibrium solidification

    Energy Technology Data Exchange (ETDEWEB)

    Beresina, A L; Kurdyumov, G V [Institute for Metal Physics, 36, Vernadsky Blvd, Kyiv-142 (Ukraine); Segida, E A, E-mail: slena54@yahoo.co

    2009-01-01

    The structure formation in hypereutectic Al-Sc and hyperperitectic Al-Zr, Al-Hf alloys with concentration of alloying element up to 1.3 at.% have been studied under conditions far from thermodynamical equilibrium depending on cooling rate and quenching temperature. The co-operative growth structures are solidified with cooling rate of 10{sup 2}-10{sup 3} K/s regardless of overheating and under cooling rate of 10{sup 5}-10{sup 6} K/s at small overheating. The phase compound of these structures is alpha-solid solutions and phase with L1{sub 2}-ordered structure or two solid solutions with different concentrations of alloying element. The large overheating leads to formation of alpha-solid solution anomalously supersaturated under cooling rate of 10{sup 5}-10{sup 6} K/s.

  17. New systemic radial velocities of suspected RR Lyrae binary stars

    Science.gov (United States)

    Guggenberger, E.; Barnes, T. G.; Kolenberg, K.

    2016-05-01

    Among the tens of thousands of known RR Lyrae stars there are only a handful that show indications of possible binarity. The question why this is the case is still unsolved, and has recently sparked several studies dedicated to the search for additional RR Lyraes in binary systems. Such systems are particularly valuable because they might allow to constrain the stellar mass. Most of the recent studies, however, are based on photometry by finding a light time effect in the timings of maximum light. This approach is a very promising and successful one, but it has a major drawback: by itself, it cannot serve as a definite proof of binarity, because other phenomena such as the Blazhko effect or intrinsic period changes could lead to similar results. Spectroscopic radial velocity measurements, on the other hand, can serve as definite proof of binarity. We have therefore started a project to study spectroscopically RR Lyrae stars that are suspected to be binaries. We have obtained radial velocity (RV) curves with the 2.1m telescope at McDonald observatory. From these we derive systemic RVs which we will compare to previous measurements in order to find changes induced by orbital motions. We also construct templates of the RV curves that can facilitate future studies. We also observed the most promising RR Lyrae binary candidate, TU UMa, as no recent spectroscopic measurements were available. We present a densely covered pulsational RV curve, which will be used to test the predictions of the orbit models that are based on the O - C variations.

  18. Secular resonances in circumstellar systems in binary stars

    Science.gov (United States)

    Bazso, A.; Pilat-Lohinger, E.; Eggl, S.; Funk, B.; Bancelin, D.

    2016-02-01

    Planet formation around single stars is already a complicated matter, but extrasolar planets are also present in binary and multiple star systems. We investigate circumstellar planets in binary star systems with stellar separations below 100 astronomical units. For a selection of 11 systems with at least one detected giant planet we determine the location and extension of the habitable zone (HZ), subject to the incident stellar flux from both stars. We work out the stability of additional hypothetical terrestrial planets in or close to the HZ in these systems. To study the secular dynamics we apply a semi-analytical method. This method employs a first-order perturbation theory to determine the secular frequencies of objects moving under the gravitational influence of two much more massive perturbers. The other part uses a single numerical integration of the equations of motion and a frequency analysis of the obtained time-series to determine the apsidal precession frequencies of the massive bodies. By combining these two parts we are able to find the location of the most important secular resonances and the regions of chaotic motion. We demonstrate that terrestrial planets interior to the giant planet’s orbit may suffer from a linear secular resonance that could prevent the existence of habitable planets. Contrary to this, close-in giant planets are less of a problem, but one has to take into account the general relativistic precession of the pericenter that can also lead to resonances.

  19. The low mass ratio contact binary system V728 Herculis

    CERN Document Server

    Erkan, Naci

    2015-01-01

    We present the orbital period study and the photometric analys of the contact binary system V728 Her. Our orbital period analysis shows that the period of the system increases (dP/dt=1.92x10^-7dyr^-1) and the mass transfer rate from the less massive component to more massive one is 2.51x10^-8M_suny^-1. In addition, an advanced sinusoidal variation in period can be attributed to the light-time effect by a tertiary component or the Applegate mechanism triggered by the secondary component. The simultaneous multicolor BVR light and radial velocity curves solution indicates that the physical parameters of the system are M1=1.8M_sun, M2=0.28M_sun, R1=1.87R_sun, R2=0.82R_sun, L1=5.9L_sun, and L2=1.2L_sun. We discuss the evolutionary status and conclude that V728 Her is a deep (f=81%), low mass ratio (q=0.16) contact binary system.

  20. Microstructure of as-cast experimental binary Mg-RE alloys

    Directory of Open Access Journals (Sweden)

    K.N. Braszczyńska-Malik

    2008-03-01

    Full Text Available Microstructure anaIyscs of as-cast cxpcrirncntal Mg-3%RE and Mg-8%RE alloys were cmicd out. tight microscopy and scanningelectron microscopy (SEM+EDX tschniqucs wcrc uscd to charactcrizc investigated materials Rcsults show thar thc as-cast dcndriticmicrosEructurc is charactcrizcd by lamcllar cutcctic of primary u phase and intcrdcndritic phasc. X-ray phasc analyses allowed theidentiticaklon of thc nrc canh clcmcnrs-rich intcrmctallic compound in thc alloys as he~ngM glzRE.

  1. Non-equilibrium grain-boundary segregation of Bi in binary Ni(Bi) alloy

    International Nuclear Information System (INIS)

    The minimum ductility of Ni(Bi) alloy caused by isothermal annealing at 750 °C or 650 °C is determined through tensile tests at room temperature. Tensile samples with minimum ductility display intergranular facets. Strong grain-boundary segregation of Bi in nanocrystalline Ni–Bi layer is observed by atom probe tomography. The minimum ductility, intergranular facets and grain-boundary segregation of Bi confirm the non-equilibrium grain-boundary segregation of Bi in Ni(Bi) alloy for the first time

  2. Observational studies of X-ray binary systems

    International Nuclear Information System (INIS)

    The subject of Chapter 1 is theoretical. The other chapters, Ch. 2 to 6, contain original observational data and efforts towards their interpretation. Of these, Ch. 3, 4 and 5 deal with massive X-ray binaries, Ch. 6 with low-mass systems and Ch. 2 with Cygnus X-3, which we have not yet been able to assign to any of these two classes. The X-ray observations described were made with the COS-B satellite. Work based on UV and optical observations is described in Ch. 5. The UV observations were made with the IUE satellite, the optical observations at several ground-based observatories. (Auth.)

  3. Properties of the components in young binary systems

    Science.gov (United States)

    Woitas, Jens

    1999-10-01

    Using near-infrared speckle-interferometry we have obtained resolved JHK-photometry for the components of 58 young binary systems. By placing the components into a color-color diagram we identify some unusual red objects that are candidates for infrared companions or substellar objects. We place a subsample that consists of the components of 14 weak-lined TTS systems (where no significant circumstellar excess emission is expected) into a color-magnitude diagram and show that in all these systems the components are coeval within the uncertainties. Particularly this is the case for the triple system HBC 358. Using the J-magnitude as an indicator for the stellar luminosity, the optical spectral type of the system and the previously justified assumption that all components are coeval we can place the components into the HRD and derive their masses by comparison with theoretical pre-main sequence evolutionary tracks. The results are the following: The distribution of mass ratios is neither clustered towards M2 / M1 = 1 nor is it a function of the primary's mass or the components' projected separation. Comparison of these results with predictions of theoretical multiple star formation models suggests that most of the systems have formed by fragmentation during protostellar collapse, and that the components' masses are principally determined by fragmentation and not by the following accretion processes. Furthermore the infrared source HV Tau C is discussed using new observational data. We show that this source is no Herbig-Haro object, but an active T Tauri star. So the HV Tau-system does not impose a problem on current models of T Tauri stars and their environment. From relative positions of the components at different epochs we derive their relative velocities and show that in most close systems orbital motion can be proved. The analysis of this orbital motion leads to an empirical mass estimate for T Tauri-stars which is larger than the masses one would expect from the

  4. The Alpha Centauri Binary System: Atmospheric Parameters and Element Abundances

    CERN Document Server

    de Mello, G F Porto; Keller, G R

    2008-01-01

    The Alpha Centauri binary system, owing to its binarity, proximity and brightness, is a fundamental calibrating object for the theory of stellar structure and evolution. This role, however, is hindered by a considerable disagreement in the published analyses of its atmospheric parameters and abundances. We report a detailed spectroscopic analysis of both components of the Alpha Centauri binary system, differentially with respect to the Sun, based on high quality spectra (R = 35 000, S/N > 1000). The atmospheric parameters of the system are found to be Teff = 5820 K, [Fe/H] = +0.24, log g = 4.34 and xi = 1.46 km/s, for Alpha Cen A, and Teff = 5240 K, [Fe/H] = +0.25, log g = 4.44 and xi = 1.28 km/s for Alpha Cen B. The parameters were derived from the simultaneous excitation & ionization equilibria of the equivalent widths of Fe I and Fe II lines, by fitting theoretical profiles to the Halpha line and from photometric calibrations, good agreement being reached between the criteria for both stars. We derived...

  5. Thermodynamic reassessment of Ni-Pr binary system

    Energy Technology Data Exchange (ETDEWEB)

    Rahou, Z., E-mail: rahou.zakarea@gmail.com; Mahdouk, K.; Moustain, D.; Otmani, S.; Kardellass, S.; Iddaoudi, A.; Selhaoui, N.

    2015-01-25

    Highlights: • The Ni-Pr has been re-assessed using the latest experimental results. • The enthalpies of formation of NiPr and Ni{sub 5}Pr measured by Kleppa were considered her for the first time. • The errors of related modeling presented in previous articles have been modified. • A self-consistent thermodynamic description of the Sm–Ni system was obtained. - Abstract: Based on the available experimental data of phase equilibria and thermodynamic properties from the literature, the Ni-Pr binary system has been thermodynamically assessed using the CALPHAD method. The solution phases, Liquid, FCC{sub A}1, DHCP and BCC{sub A}2 were modeled as substitutional solution phases, for which the excess Gibbs energies were formulated with Redlich–Kister polynomials. All intermetallic phases were described as stoichiometric compounds. Subsequently, a set of self-consistent thermodynamic parameters describing various phases in this binary system has been obtained. The calculated results reproduce well the corresponding experimental data.

  6. On stress relaxation timescales for dense binary particulate systems

    Science.gov (United States)

    Mao, Shaolin

    2015-06-01

    We study contact stress relaxation timescales, especially the temporal correlation involved in dense binary particulate systems, which offers insight into the intriguing relationship between the contact stresses and the contact time of particle interactions under non-equilibrium state. The contact time (also referred to as contact age) of a pair of particles is defined by the duration between current time and the instant when the contact was formed. The interspecies inter-particles contact stresses are derived from Liouville's theorem. We apply particle dynamics methods (e.g. molecular dynamics, discrete element method) to simulate 3D dense binary particulate systems with periodic boundary conditions. External perturbation is exerted on the system to balance the dissipation of energy due to the viscoelastic collisions. The contact stresses, Reynolds stresses, and the probability density function of the contact time of particles are predicted at different volume fraction of particles. The obtained stress-strain rate data are used to examine the constitutive relation of macroscopic materials. The study targets the impact of the short-term and the long-term contact/collision on the contact stress relaxation. The simulation results reveal distinct effects of the short-term and the long-term contact/collision on the contact stresses, which have been treated by only an averaged expression of particle interactions in discrete element methods before.

  7. Evidence for broken ergodicity due to chemical alloying from the dissociation kinetics of binary clusters

    OpenAIRE

    Yurtsever, Ersin; Calvo, Florent

    2014-01-01

    The interplay between thermal relaxation and statistical dissociation in binary Morse clusters (AB)N has been investigated using numerical simulations and simple statistical approaches, for a variety of interaction parameters covering miscible and non-miscible regimes. While all clusters exhibit a core/shell phase separation pattern in their most stable, T = 0 structure, different melting mechanisms are identified depending on the ranges and their mismatch, including two-step melting of the s...

  8. Thermodynamic optimization of Co–Ge binary system

    Energy Technology Data Exchange (ETDEWEB)

    Dong, S.S.; Liu, S.G. [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); Tao, X.M. [College of Physical Science and Technology, Guangxi University, Nanning, Guangxi 530004 (China); Xiao, F.H.; Huang, L.H.; Yang, F.; He, Y.; Chen, Q. [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); Liu, H.S., E-mail: hsliu@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); Jin, Z.P. [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China)

    2013-11-20

    Graphical abstract: - Highlights: • The Co–Ge binary system was reassessed and optimized. • The first-principle approach was employed to calculate formation enthalpies of two compounds. • A self-consistent set of thermodynamic parameters was obtained. • The experimental data were well reproduced in the present optimization. - Abstract: Phase diagram of Co–Ge binary system was thermodynamically assessed by using CALPHAD approach in this study. The excess Gibbs energy of the solution phases, liquid, α(Co) and ε(Co), were modeled with Redlich–Kister polynomial. Magnetic contribution to the Gibbs energy was also taken into account for α(Co) and ε(Co). Considering its crystal structure and solubility range, the intermetallic compound βCo{sub 5}Ge{sub 3}, with B8{sub 2}-structure, was particularly described with a three-sublattice model, (Co,Va){sub 1}:(Co){sub 4}:(Co,Ge){sub 3}. And the compound CoGe was described with two-sublattice model according to its crystal structure. Other intermetallic compounds were described as stoichiometric phases because of their narrow homogeneity ranges or unknown crystal structure. In order to obtain a reasonable description of several Co–Ge compounds, first-principle calculations were performed before optimization to determine their formation enthalpies. Finally, a set of thermodynamic parameters was finally obtained so that most data of phase boundaries and thermodynamic properties of various phases were reproduced in present optimization.

  9. Absolute properties of the binary system BB Pegasi

    CERN Document Server

    Kalomeni, B; Keskin, V; Degirmenci, O L; Ulas, B; Kose, O

    2007-01-01

    We present a ground based photometry of the low-temperature contact binary BB Peg. We collected all times of mid-eclipses available in literature and combined them with those obtained in this study. Analyses of the data indicate a period increase of 3.0(1) x 10^{-8} days/yr. This period increase of BB Peg can be interpreted in terms of the mass transfer 2.4 x 10^{-8} Ms yr^{-1} from the less massive to the more massive component. The physical parameters have been determined as Mc = 1.42 Ms, Mh = 0.53 Ms, Rc = 1.29 Rs, Rh = 0.83 Rs, Lc = 1.86 Ls, and Lh = 0.94 Ls through simultaneous solution of light and of the radial velocity curves. The orbital parameters of the third body, that orbits the contact system in an eccentric orbit, were obtained from the period variation analysis. The system is compared to the similar binaries in the Hertzsprung-Russell and Mass-Radius diagram.

  10. New systemic radial velocities of suspected RR Lyrae binary stars

    CERN Document Server

    Guggenberger, Elisabeth; Kolenberg, Katrien

    2015-01-01

    Among the tens of thousands of known RR Lyrae stars there are only a handful that show indications of possible binarity. The question why this is the case is still unsolved, and has recently sparked several studies dedicated to the search for additional RR Lyraes in binary systems. Such systems are particularly valuable because they might allow to constrain the stellar mass. Most of the recent studies, however, are based on photometry by finding a light time effect in the timings of maximum light. This approach is a very promising and successful one, but it has a major drawback: by itself, it cannot serve as a definite proof of binarity, because other phenomena such as the Blazhko effect or intrinsic period changes could lead to similar results. Spectroscopic radial velocity measurements, on the other hand, can serve as definite proof of binarity. We have therefore started a project to study spectroscopically RR Lyrae stars that are suspected to be binaries. We have obtained radial velocity (RV) curves with t...

  11. Wobbling and precessing jets from warped disks in binary systems

    CERN Document Server

    Sheikhnezami, Somayeh

    2015-01-01

    We present results of the first ever three-dimensional (3D) magnetohydrodynamic (MHD) simulations of the accretion-ejection structure. We investigate the 3D evolution of jets launched symmetrically from single stars but also jets from warped disks in binary systems. We have applied various model setups and tested them by simulating a stable and bipolar symmetric 3D structure from a single star-disk-jet system. Our reference simulation maintains a good axial symmetry and also a bipolar symmetry for more than 600 rotations of the inner disk confirming the quality of our model setup. We have then implemented a 3D gravitational potential (Roche potential) due to a companion star and run a variety of simulations with different binary separations and mass ratios. These simulations show typical 3D deviations from axial symmetry, such as jet inclination outside the Roche lobe or spiral arms forming in the accretion disk. In order to find indication for precession effects, we have also run an exemplary parameter setup...

  12. Modulated Gamma-ray emission from compact millisecond pulsar binary systems

    CERN Document Server

    Bednarek, W

    2013-01-01

    A significant amount of the millisecond pulsars has been discovered within binary systems. In several such binary systems the masses of the companion stars have been derived allowing to distinguish two classes of objects, called the Black Widow and the Redback binaries. Pulsars in these binary systems are expected to produce winds which, colliding with stellar winds, create conditions for acceleration of electrons. These electrons should interact with the anisotropic radiation from the companion stars producing gamma-ray emission modulated with the orbital period of the binary system. We consider the interaction of a millisecond pulsar (MSP) wind with a very inhomogeneous stellar wind from the companion star within binary systems of the Black Widow and Redback types. It is expected that the pulsar wind should mix efficiently with the inhomogeneous stellar wind. Electrons accelerated in such mixed, turbulent winds can interact with the magnetic field and also strong radiation from the companion star producing ...

  13. The effect of Nb-B inoculation on binary hypereutectic and near-eutectic LM13 Al-Si cast alloys

    OpenAIRE

    Nowak, M.; Bolzoni, L.; Nadendla, HB

    2015-01-01

    This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Hyper-eutectic Al-Si alloys are used for wear-resistant components, such as pistons, because their microstructure is composed by ductile aluminium dendrites and hard primary silicon particles. In this study the effect of Nb-B inoculation on the microstructural features of binary hyper-eutectic and near-eutectic LM13 Al-Si alloys is assessed. It is found that the inoculation with Nb-based c...

  14. First analysis of a numerical benchmark for 2D columnar solidification of binary alloys

    OpenAIRE

    Arquis, Eric; Bellet, Michel; Combeau, Hervé; Fautrelle, Yves; Gobin, Dominique; Budenkova, Olga; Dussoubs, Bernard; Duterrail, Yves; Kumar, Arvind; Mosbah, Salem; Rady, Mohamed; Gandin, Charles-André; Goyeau, Benoit; Zaloznik, Miha

    2011-01-01

    During the solidification of metal alloys, chemical heterogeneities at the product scale (macrosegregation) develop. Numerical simulation tools are beginning to appear in the industry, however their predictive capabilities are still limited. We present a numerical benchmark exercise treating the performance of models in the prediction of macrosegregation. In a first stage we defined a "minimal" (i.e. maximally simplified) solidification model, describing the coupling of the solidification of ...

  15. Investigations of linear contraction and shrinkage stresses development in hypereutectic al-si binary alloys

    OpenAIRE

    J. Mutwil; Kujawa, K.; G. Bajon; P. Hajn

    2009-01-01

    Shrinkage phenomena during solidification and cooling of hypereutectic aluminium-silicon alloys (AlSi18, AlSi21) have been examined. A vertical shrinkage rod casting with circular cross-section (constant or fixed: tapered) has been used as a test sample. Two type of experiments have been conducted: 1) on development of the test sample linear dimension changes (linear expansion/contraction), 2) on development of shrinkage stresses in the test sample. By the linear contraction experiments the l...

  16. Mechanical alloying in the Fe-Cu system

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gente, C.; Bormann, R.

    1998-01-01

    in the Fe-Cu system is; (3) where the positive energy is stored in the alloys; (4) what the decomposition process of the supersaturated alloys is; and (5) what type of magnetic properties the new materials have. The elucidation of these problems will shed light on the understanding of the mechanisms...... for the preparation of materials under highly non-equilibrium conditions in systems with positive heats of mixing by mechanical alloying....

  17. Thermal expansion of solid solutions in apatite binary systems

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, Alexander V.; Bulanov, Evgeny N., E-mail: bulanoven@gmail.com; Korokin, Vitaly Zh.

    2015-01-15

    Graphical abstract: Thermal dependencies of volume thermal expansion parameter for with thermal expansion diagrams for Pb{sub 5}(PO{sub 4}){sub 3}F{sub x}Cl{sub 1−x}. - Highlights: • Solid solutions in three apatitic binary systems were investigated via HT-XRD. • Thermal expansion coefficients of solid solutions in the systems were calculated. • Features of the thermal deformation of the apatites were described. • Termoroentgenography is a sensitive method for the investigation of isomorphism. - Abstract: High-temperature insitu X-ray diffraction was used to investigate isomorphism and the thermal expansion of apatite-structured compounds in three binary systems in the entire temperature range of the existence of its hexagonal modifications. Most of the studied compounds are highly expandable (α{sub l} > 8 × 10{sup 6} (K{sup −1})). In Pb{sub 5}(PO{sub 4}){sub 3}F–Pb{sub 5}(PO{sub 4}){sub 3}Cl system, volume thermal expansion coefficient is independence from the composition at 573 K. In Pb{sub 5}(PO{sub 4}){sub 3}Cl–Pb{sub 5}(VO{sub 4}){sub 3}Cl, the compound with equimolar ratio of substituted atoms has constant volume thermal expansion coefficient in temperature range 298–973 K. Ca{sub 5}(PO{sub 4}){sub 3}Cl–Pb{sub 5}(PO{sub 4}){sub 3}Cl system is characterized by the most thermal sensitive composition, in which there is an equal ratio of isomorphic substituted atoms.

  18. Corrosion behavior of as-cast binary Mg-Bi alloys in Hank's solution

    Directory of Open Access Journals (Sweden)

    Wei-li Cheng

    2015-11-01

    Full Text Available Biodegradable Mg-xBi (x = 3, 6 and 9wt.% alloys were fabricated by ingot casting, and the change of corrosion behavior of the alloys in the Hank's solution was analyzed with respect to the microstructure using optical micrograph (OM, X-ray diffraction (XRD, scanning electron microscope (SEM equipped with an energy dispersive X-ray spectrometer (EDS, electrochemical and immersion tests. The results show that the microstructures of the as-cast Mg-Bi alloys mainly consisted of dendritic ?Mg grains and Mg3Bi2 phase in common, with the secondary dendrite arm spacing (SDAS decreasing significantly from 41.2 靘 to 25.4 靘 and the fraction of Mg3Bi2 increasing from 3.1% to 10.7%. Furthermore, the corrosion rate increasing from 1.32 mm昦-1 to 8.07 mm昦-1 as the Bi content was increased from 3wt.% to 9wt.%. The reduced corrosion resistance was mainly ascribed to the increasing fraction of the second phase particles, which bring positive effects on the development of pitting.

  19. Relation between emission properties and the surface composition of binary and ternary iridium base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gnuchev, N.M.; Gell, A.P.

    1982-12-01

    Changes in the surface composition and emission properties of iridium alloys with 1.8 and 2.7 at. % of cerium as well as Ir - 8% Ce - 5% Mo and Ir - 8% Ce - 15% Re in the process of thermal treatment in the temperature range of 1400-2000 K were studied. Thermoelectron work function and specimen Auger spectra were detected. The investigations were carried on by experimental instruments equipped with three-grid quasi-spherical analyzers of approximately 0.5% resolution. The investigations have shown that heating at 900-2000 K results in marked improvement of emission properties of both two-and three-component alloys. The surface is cleaned from contaminants and its elementary composition and structure reach optimal ones. At the same time intensive cerium evaporation occurs and emission capability of alloys of low cerium content drops at such high temperatures. So, heating of Ir - 1% Ce specimen during several hours at 2000 K resulted in reduction of cerium Auger peak amplitude and increase in work function by 0.3 eV.

  20. Influence of silicon concentration on linear contraction process of Al-Si binary alloy

    Directory of Open Access Journals (Sweden)

    J. Mutwil

    2008-12-01

    Full Text Available Investigations of shrinkage phenomena during solidification and cooling of aluminium and aluminium-silicon alloys (AlSi5, AlSi7, AlSi9, AlSi11, AlSi12.5, AlSi18, AlSi21 have been conducted. A vertical shrinkage rod casting with circular cross-section (constant or fixed: tapered has been used as a test sample. By constant cross-section a test channel mould was parted and allowed a constrained contraction to examine. No parted test channel mould was tapered and allowed an unconstrained contraction to investigate. In the experiments the dimensions changes of solidifying test bar and the test mould have been registered, what has allowed to explain a mechanism of pre-shrinkage extension of solidifying metals and alloys. Registered time dependence of the test bar and the test mould dimension changes have shown, that so-called pre-shrinkage extension has been by mould thermal extension caused. The investigation results have also shown that time- and temperature dependences of shrinkage of Al-Si alloys have been on silicon concentration depended.

  1. Evolution of an Accretion Disk in Binary Black Hole Systems

    CERN Document Server

    Kimura, Shigeo S; Toma, Kenji

    2016-01-01

    We investigate evolution of an accretion disk in binary black hole (BBH) systems, the importance of which is now increasing due to its close relationship to possible electromagnetic counterparts of the gravitational waves (GWs) from mergers of BBHs. Perna et al. (2016) proposed a novel evolutionary scenario of an accretion disk in BBHs in which a disk eventually becomes "dead", i.e., the magnetorotational instability (MRI) becomes inactive. In their scenario, the dead disk survives until {\\it a few seconds before} the merger event. We improve the dead disk model and propose another scenario, taking account of effects of the tidal torque from the companion and the critical ionization degree for MRI activation more carefully. We find that the mass of the dead disk is much lower than that in the Perna's scenario. When the binary separation sufficiently becomes small, the tidal heating reactivates MRI and mass accretion onto the black hole (BH). We also find that this disk "revival" happens {\\it many years before...

  2. Be discs in binary systems - I. Coplanar orbits

    Science.gov (United States)

    Panoglou, Despina; Carciofi, Alex C.; Vieira, Rodrigo G.; Cyr, Isabelle H.; Jones, Carol E.; Okazaki, Atsuo T.; Rivinius, Thomas

    2016-09-01

    Be stars are surrounded by outflowing circumstellar matter structured in the form of decretion discs. They are often members of binary systems, where it is expected that the decretion disc interacts both radiatively and gravitationally with the companion. In this work we study how various orbital (period, mass ratio and eccentricity) and disc (viscosity) parameters affect the disc structure in coplanar binaries. The main effects of the secondary on the disc are its truncation and the accumulation of material inwards of truncation. We find two limiting cases with respect to the effects of eccentricity: in circular or nearly circular prograde orbits, the disc maintains a rotating, constant in shape, configuration, which is locked to the orbital phase. The disc structure appears smaller in size, more elongated and more massive for small viscosity parameter, small orbital separation and/or high mass ratio. In highly eccentric orbits, the effects are more complex, with the disc structure strongly dependent on the orbital phase. We also studied the effects of binarity in the disc continuum emission. Since the infrared and radio SED are sensitive to the disc size and density slope, the truncation and matter accumulation result in considerable modifications in the emergent spectrum. We conclude that binarity can serve as an explanation for the variability exhibited in observations of Be stars, and that our model can be used to detect invisible companions.

  3. Solar-type cycles in close binary systems

    International Nuclear Information System (INIS)

    Solar-type cycles in late-type secondary components of cataclysmic variables can produce cyclical variations of the quiescent luminosity, the time intervals between consecutive outbursts of dwarf-nova systems, and the orbital period. Analysis of the long-term light curves of several types of close binary systems suggests cyclical variations of the mass-transfer rate which can be ascribed to fractional changes of the radii of the late-type secondaries by Delta R/R in the range 0.00006-0.0003, as expected for a typical solar cycle. The probability density function of the periods of the cycles discovered in both CVs and single main-sequence stars are peaked around 6 yr. The periods of the cycles do not seem to be affected by the rotation regime of the star. A possible correlation between these cycles and the recurrence times of recurrent novae is suggested. 85 refs

  4. Glass transition and mixing thermodynamics of a binary eutectic system.

    Science.gov (United States)

    Tu, Wenkang; Chen, Zeming; Gao, Yanqin; Li, Zijing; Zhang, Yaqi; Liu, Riping; Tian, Yongjun; Wang, Li-Min

    2014-02-28

    A quantitative evaluation of the contribution of mixing thermodynamics to glass transition is performed for a binary eutectic benzil and m-nitroaniline system. The microcalorimetric measurements of the enthalpy of mixing give small and positive values, typically ~200 J mol(-1) for the equimolar mixture. The composition dependence of the glass transition temperature, T(g), is found to show a large and negative deviation from the ideal mixing rule. The Gordon-Taylor and Couchman-Karasz models are subsequently applied to interpret the T(g) behavior, however, only a small fraction of the deviation is explained. The analyses of the experimental results manifest quantitatively the importance of the mixing thermodynamics in the glass transition in miscible systems.

  5. Orbital evolution of mass-transferring eccentric binary systems. I. Phase-dependent evolution

    OpenAIRE

    Dosopoulou, Fani; Kalogera, Vicky

    2016-01-01

    Observations reveal that mass-transferring binary systems may have non-zero orbital eccentricities. The time-evolution of the orbital semi-major axis and eccentricity of mass-transferring eccentric binary systems is an important part of binary evolution theory and has been widely studied. However, various different approaches and assumptions on the subject have made the literature difficult to comprehend and comparisons between different orbital element time-evolution equations not easy to ma...

  6. Study of dynamic properties for NaK binary liquid alloy using first principle and theoretical predictions of isothermal bulk modulus using elastic constants

    International Nuclear Information System (INIS)

    Study of atomic motions in the binary liquid alloys have been studied in terms of dynamical variables like velocity auto correlation, power spectrum and mean square displacement. Elastic constants and isothermal bulk modulus have been calculated to see the effeectiveness of ab-initio pseudopotentials which has been used in this paper. This appraoch is free from the fitting parameters and results obtained using this appraoch have been found very close to the average values

  7. Study of dynamic properties for NaK binary liquid alloy using first principle and theoretical predictions of isothermal bulk modulus using elastic constants

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Anil, E-mail: anil-t2001@yahoo.com; Kashyap, Rajinder [Department of Physics, Govt. P. G. College Solan-173212, Himachal Pradesh (India); Sharma, Nalini; Ahluwalia, P. K. [Department of Physics, Himachal Pradesh University Shimla-171005, Himachal Pradesh (India)

    2014-04-24

    Study of atomic motions in the binary liquid alloys have been studied in terms of dynamical variables like velocity auto correlation, power spectrum and mean square displacement. Elastic constants and isothermal bulk modulus have been calculated to see the effeectiveness of ab-initio pseudopotentials which has been used in this paper. This appraoch is free from the fitting parameters and results obtained using this appraoch have been found very close to the average values.

  8. The disruption of multiplanet systems through resonance with a binary orbit.

    Science.gov (United States)

    Touma, Jihad R; Sridhar, S

    2015-08-27

    Most exoplanetary systems in binary stars are of S-type, and consist of one or more planets orbiting a primary star with a wide binary stellar companion. Planetary eccentricities and mutual inclinations can be large, perhaps forced gravitationally by the binary companion. Earlier work on single planet systems appealed to the Kozai-Lidov instability wherein a sufficiently inclined binary orbit excites large-amplitude oscillations in the planet's eccentricity and inclination. The instability, however, can be quenched by many agents that induce fast orbital precession, including mutual gravitational forces in a multiplanet system. Here we report that orbital precession, which inhibits Kozai-Lidov cycling in a multiplanet system, can become fast enough to resonate with the orbital motion of a distant binary companion. Resonant binary forcing results in dramatic outcomes ranging from the excitation of large planetary eccentricities and mutual inclinations to total disruption. Processes such as planetary migration can bring an initially non-resonant system into resonance. As it does not require special physical or initial conditions, binary resonant driving is generic and may have altered the architecture of many multiplanet systems. It can also weaken the multiplanet occurrence rate in wide binaries, and affect planet formation in close binaries. PMID:26310763

  9. Structural alloys for superconducting magnets in fusion energy systems

    International Nuclear Information System (INIS)

    The behaviour of selected alloys for superconducting magnet structures in fusion energy systems is reviewed with emphasis on the following austenitic stainless steels (AISI grades 304, 310S and 316), nitrogen-strengthened austenitic stainless steels (types 304LN, 316LN and 21Cr-6Ni-9Mn) and aluminium alloys (grades 5083, 6061 and 2219). The mechanical and physical properties of the selected alloys at 4 K are reviewed. Welding, the properties of weldments, and other fabrication considerations are briefly discussed. The available information suggests that several commercial alloys have adequate properties at 4 K and sufficient fabrication characteristics for the large magnet structures needed for fusion energy systems. (orig.)

  10. Structural alloys for superconducting magnets in fusion energy systems

    International Nuclear Information System (INIS)

    The behavior of selected alloys for superconducting magnet structures in fusion energy systems is reviewed with emphasis on austenitic stainless steels (AISI grades 304, 310S, and 316), nitrogen-strengthened austenitic stainless steels (304LN, 316LN, and 21Cr-6Ni-9Mn) and aluminum alloys (5083, 6061, and 2219). The mechanical and physical properties of the selected alloys at 40K are reviewed. Welding, properties of weldments, and other fabrication considerations are briefly discussed. The available information suggests that several commercial alloys have adequate properties at 40K and sufficient fabrication characteristics for the large magnet structures needed for fusion energy systems

  11. Developing of an expert system for nonferrous alloy design

    Institute of Scientific and Technical Information of China (English)

    李义兵; 何红波; 周继承; 李斌

    2004-01-01

    Expert systems have been used widely in the predictions and design of alloy systems. But the expert systems are based on the macroscopic models that have no physical meanings. Microscopic molecular dynamics is also a standard computational technique used in materials science. An approach is presented to the design system of nonferrous alloy that integrates the molecular dynamical simulation together with an expert system. The knowledge base in the expert system is able to predict nonferrous alloy properties by using machine learning technology. The architecture of the system is presented.

  12. Influence of silicon concentration on linear contraction process of Al-Si binary alloy

    OpenAIRE

    J. Mutwil; Kujawa, K.; Marczewski, P.; P. Michajłow

    2008-01-01

    Investigations of shrinkage phenomena during solidification and cooling of aluminium and aluminium-silicon alloys (AlSi5, AlSi7, AlSi9, AlSi11, AlSi12.5, AlSi18, AlSi21) have been conducted. A vertical shrinkage rod casting with circular cross-section (constant or fixed: tapered) has been used as a test sample. By constant cross-section a test channel mould was parted and allowed a constrained contraction to examine. No parted test channel mould was tapered and allowed an unconstrained contra...

  13. Thermodynamic assessment of the Mo-Re binary system

    International Nuclear Information System (INIS)

    The existing Mo-Re phase diagrams are reviewed and a thermodynamic calculation of the Mo-Re binary system is undertaken. The Gibbs energies are estimated for liquid, bcc (Mo), hcp (Re), σ and χ phases. The liquid, bcc (Mo) and hcp (Re) phases are described by a regular solution model, whereas the σ and χ phases are described respectively by three-sublattice models. For the σ phase, two thermodynamic models are used for calculations and the results are compared. The models take into account the crystallographic structure and similarity between the σ and χ phases. The calculated results remove the ambiguity of the existing phase diagram data and are compared with the experimental data in the literature

  14. Hybridizing Gravitationl Waveforms of Inspiralling Binary Neutron Star Systems

    Science.gov (United States)

    Cullen, Torrey; LIGO Collaboration

    2016-03-01

    Gravitational waves are ripples in space and time and were predicted to be produced by astrophysical systems such as binary neutron stars by Albert Einstein. These are key targets for Laser Interferometer and Gravitational Wave Observatory (LIGO), which uses template waveforms to find weak signals. The simplified template models are known to break down at high frequency, so I wrote code that constructs hybrid waveforms from numerical simulations to accurately cover a large range of frequencies. These hybrid waveforms use Post Newtonian template models at low frequencies and numerical data from simulations at high frequencies. They are constructed by reading in existing Post Newtonian models with the same masses as simulated stars, reading in the numerical data from simulations, and finding the ideal frequency and alignment to ``stitch'' these waveforms together.

  15. Thermodynamic modeling of the Ba - Mg binary system

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Xin; Li, Changrong; Du, Zhenmin; Guo, Cuiping; Chen, Sicheng [Univ. of Science and Technology, Beijing (China). School of Materials Science and Engineering

    2013-04-15

    On the basis of the thermochemical and phase equilibrium experimental data, the phase diagram of the Ba - Mg binary system has been assessed by means of the calculation of phase diagrams technique. The liquid phase is of unlimited solubility and modeled as a solution phase using the Redlich-Kister equation. The intermetallic compounds, Mg{sub 17}Ba{sub 2}, Mg{sub 23}Ba{sub 6} and Mg{sub 2}Ba, with no solubility ranges are treated as strict stoichiometric compounds with the formula Mg{sub m} Ba{sub n}. Two terminal phases, BccBa and HcpMg, are kept as solution phases, since the solubilities of the two phases are of considerable importance. After optimization, a set of self-consistent thermodynamic parameters has been obtained. The calculated values agree well with the available experimental data.

  16. Viscosity mixing rules for binary systems containing one ionic liquid.

    Science.gov (United States)

    Tariq, Mohammed; Altamash, Tausif; Salavera, Daniel; Coronas, Alberto; Rebelo, Luis P N; Canongia Lopes, Jose N

    2013-06-24

    In this work the applicability of four of the most commonly used viscosity mixing rules to [ionic liquid (IL)+molecular solvent (MS)] systems is assessed. More than one hundred (IL+MS) binary mixtures were selected from the literature to test the viscosity mixing rules proposed by 1) Hind (Hi), 2) Grunberg and Nissan (G-N), 3) Herric (He) and 4) Katti and Chaudhri (K-C). The analyses were performed by estimating the average (absolute or relative) deviations, AADs and ARDs, between the available experimental data and the predicted ideal mixture viscosity values obtained by means of each rule. The interaction terms corresponding to the adjustable parameters inherent to each rule were also calculated and their trends discussed. PMID:23650138

  17. Phase evolution during crystallization of nanocomposite alloys with Co:Fe ratios in the two-phase region of the binary Fe-Co phase diagram

    International Nuclear Information System (INIS)

    A series of alloys was prepared to investigate the crystallization of Co-rich HiTPerm-type alloys [(Co1-xFex)88Zr7B4Cu1] with Fe:Co ratios within or near the two-phase (bcc+fcc) region of the binary phase diagram. The goal of this work is to better understand the phase evolution and crystallization of alloys in which the Fe-Co binary phase diagram predicts more than one transition metal rich primary crystalline phase to be present in equilibrium at the primary crystallization temperature. X-ray diffraction, transmission electron microscopy, and high-temperature vibrating-sample magnetometry have been performed to identify the first phase to crystallize and to follow the evolution of phases during crystallization. The bcc phase appears to be the primary crystalline phase that forms first after annealing at 450 degree sign C for 1 h, in agreement with previous work on Co-rich nanocomposite alloys. We observe that as the Co concentration is increased, the fcc crystalline phase forms at lower annealing temperatures and its volume fraction increases for a given annealing temperature

  18. Interconnection between microstructure and microhardness of directionally solidified binary Al-6wt.%Cu and multicomponent Al-6wt.%Cu-8wt.%Si alloys

    Directory of Open Access Journals (Sweden)

    ANGELA J. VASCONCELOS

    2016-06-01

    Full Text Available An experimental study has been carried out to evaluate the microstructural and microhardness evolution on the directionally solidified binary Al-Cu and multicomponent Al-Cu-Si alloys and the influence of Si alloying. For this purpose specimens of Al-6wt.%Cu and Al-6wt.%Cu-8wt.%Si alloys were prepared and directionally solidified under transient conditions of heat extraction. A water-cooled horizontal directional solidification device was applied. A comprehensive characterization is performed including experimental dendrite tip growth rates (VL and cooling rates (TR by measuring Vickers microhardness (HV, optical microscopy and scanning electron microscopy with microanalysis performed by energy dispersive spectrometry (SEM-EDS. The results show, for both studied alloys, the increasing of TR and VL reduced the primary dendrite arm spacing (l1 increasing the microhardness. Furthermore, the incorporation of Si in Al-6wt.%Cu alloy to form the Al-6wt.%Cu-8wt.%Si alloy influenced significantly the microstructure and consequently the microhardness but did not affect the primary dendritic growth law. An analysis on the formation of the columnar to equiaxed transition (CET is also performed and the results show that the occurrence of CET is not sharp, i.e., the CET in both cases occurs in a zone rather than in a parallel plane to the chill wall, where both columnar and equiaxed grains are be able to exist.

  19. Interconnection between microstructure and microhardness of directionally solidified binary Al-6wt.%Cu and multicomponent Al-6wt.%Cu-8wt.%Si alloys.

    Science.gov (United States)

    Vasconcelos, Angela J; Kikuchi, Rafael H; Barros, André S; Costa, Thiago A; Dias, Marcelino; Moreira, Antonio L; Silva, Adrina P; Rocha, Otávio L

    2016-05-31

    An experimental study has been carried out to evaluate the microstructural and microhardness evolution on the directionally solidified binary Al-Cu and multicomponent Al-Cu-Si alloys and the influence of Si alloying. For this purpose specimens of Al-6wt.%Cu and Al-6wt.%Cu-8wt.%Si alloys were prepared and directionally solidified under transient conditions of heat extraction. A water-cooled horizontal directional solidification device was applied. A comprehensive characterization is performed including experimental dendrite tip growth rates (VL) and cooling rates (TR) by measuring Vickers microhardness (HV), optical microscopy and scanning electron microscopy with microanalysis performed by energy dispersive spectrometry (SEM-EDS). The results show, for both studied alloys, the increasing of TR and VL reduced the primary dendrite arm spacing (l1) increasing the microhardness. Furthermore, the incorporation of Si in Al-6wt.%Cu alloy to form the Al-6wt.%Cu-8wt.%Si alloy influenced significantly the microstructure and consequently the microhardness but did not affect the primary dendritic growth law. An analysis on the formation of the columnar to equiaxed transition (CET) is also performed and the results show that the occurrence of CET is not sharp, i.e., the CET in both cases occurs in a zone rather than in a parallel plane to the chill wall, where both columnar and equiaxed grains are be able to exist.

  20. Interconnection between microstructure and microhardness of directionally solidified binary Al-6wt.%Cu and multicomponent Al-6wt.%Cu-8wt.%Si alloys.

    Science.gov (United States)

    Vasconcelos, Angela J; Kikuchi, Rafael H; Barros, André S; Costa, Thiago A; Dias, Marcelino; Moreira, Antonio L; Silva, Adrina P; Rocha, Otávio L

    2016-05-31

    An experimental study has been carried out to evaluate the microstructural and microhardness evolution on the directionally solidified binary Al-Cu and multicomponent Al-Cu-Si alloys and the influence of Si alloying. For this purpose specimens of Al-6wt.%Cu and Al-6wt.%Cu-8wt.%Si alloys were prepared and directionally solidified under transient conditions of heat extraction. A water-cooled horizontal directional solidification device was applied. A comprehensive characterization is performed including experimental dendrite tip growth rates (VL) and cooling rates (TR) by measuring Vickers microhardness (HV), optical microscopy and scanning electron microscopy with microanalysis performed by energy dispersive spectrometry (SEM-EDS). The results show, for both studied alloys, the increasing of TR and VL reduced the primary dendrite arm spacing (l1) increasing the microhardness. Furthermore, the incorporation of Si in Al-6wt.%Cu alloy to form the Al-6wt.%Cu-8wt.%Si alloy influenced significantly the microstructure and consequently the microhardness but did not affect the primary dendritic growth law. An analysis on the formation of the columnar to equiaxed transition (CET) is also performed and the results show that the occurrence of CET is not sharp, i.e., the CET in both cases occurs in a zone rather than in a parallel plane to the chill wall, where both columnar and equiaxed grains are be able to exist. PMID:27254454

  1. Matrix effect in quantitative Auger analysis of binary alloys: Comparison between the measured and the calculated values

    Science.gov (United States)

    LI, Ri-Sheng; LI, Chun-Fei

    1990-05-01

    Matrix factors in quantitative AES analyses of binary alloys of AlNi, AuCu, AuNi, CuNi, CuPt and NiPt were studied. Using the in-situ scraping method, matrix factors were experimentally determined with an accuracy better than 5% or 10%. For comparison, matrix factors were calculated using the methods of: Reuter and Seah and Dench (R-SD); Reuter and Tokutaka, Nishimori and Hayashi (R-TNH); Reuter and Tanuma, Powell and Penn (R-TPP); Shimizu and Ichimura and Seah and Dench (SISD); SITNH and SITPP. By comparing the calculated values with the experimental results, we conclude that, the choice of the backscattering factor data, either after R or after SI, only marginally affects the resulting matrix effect despite the fact that their data differ considerably from each other. The most important effect stems from the choice of escape depth. When SD's data are adopted, the calculated values differ significantly from the experimental results except in the case of CuNi. By comparison, when TNH's data (in all of the studied cases) or TPP's data (except in the case of Al-Ni) are adopted, the calculated values are in good agreement with the observed values. This result also implies that the escape depth of Auger electrons depends on the materials in the manner suggested by TNH and TPP rather than the one suggested by SD.

  2. Phase-field crystal study for the characteristics and influence factors of grain boundary segregation in binary alloys

    International Nuclear Information System (INIS)

    Grain boundary segregation strongly modifies grain boundary behaviors and affects the physical and mechanical properties of solid polycrystalline materials. In this paper, we study the grain boundary segregation characteristics and the variation law of grain boundary segregation with temperature, crystal misorientation angle, undercooling, lattice mismatch and the difference of interspecies bond energy and self-bond energy using the binary-alloy phase-field crystal model. The simulation results show that the solute atoms segregate into individual dislocation regions for the low-angle grain boundary while the solute atoms homogeneously segregate into the entire boundary for the high-angle grain boundary with nonzero initial concentration. The degree of segregation strongly increases when the temperature, the difference of interspecies bond energy and the self-bond energy decrease, and when misorientation and undercooling increase. Small lattice mismatches did not strongly affect segregation; however, the higher mismatch has obvious effects on segregation. Our simulation results agree well with theoretical and experimental results. (paper)

  3. Obtaining Mixed-Basis Ising-Like Expansions of Binary Alloys from First Principles

    Science.gov (United States)

    Hart, Gus L. W.; Sanati, Mahdi; Wang, Ligen; Zunger, Alex

    2002-03-01

    Many electronic and structural properties of A_1-xBx alloys can be predicted theoretically if one can find (and quickly compute) the ``configurational energy function''--that is, the energy for any given configuration of A and B atoms on the crystal lattice. Cluster expansion methods provide one such approach. We describe our mixed-basis cluster expansion (MBCE) based on first-principles total energy calculations for only a few ordered A_mBn compounds. Our MBCE can robustly predict a variety of material properties including ground states, phase diagrams, precipitate formation, etc. Specifically, we illustrate how systematic choice of interaction parameters, numerical parameters, and choice of input structures can significantly increase the accuracy and the predictive capability of the expansion. We illustrate how the fit of LDA data can be done essentially automatically. Examples include Cu-Au, Ni-Pt, and Sc_1-xBox_xS.

  4. Modeling Mergers of Known Galactic Systems of Binary Neutron Stars

    CERN Document Server

    Feo, Alessandra; Maione, Francesco; Löffler, Frank

    2016-01-01

    We present a study of the merger of six different known galactic systems of binary neutron stars (BNS) of unequal mass with a mass ratio between $0.75$ and $0.99$. Specifically, these systems are J1756-2251, J0737-3039A, J1906+0746, B1534+12, J0453+1559 and B1913+16. We follow the dynamics of the merger from the late stage of the inspiral process up to $\\sim$ 20 ms after the system has merged, either to form a hyper-massive neutron star (NS) or a rotating black hole (BH), using a semi-realistic equation of state (EOS), namely the seven-segment piece-wise polytropic SLy with a thermal component. For the most extreme of these systems ($q=0.75$, J0453+1559), we also investigate the effects of different EOSs: APR4, H4, and MS1. Our numerical simulations are performed using only publicly available open source code such as, the Einstein Toolkit code deployed for the dynamical evolution and the LORENE code for the generation of the initial models. We show results on the gravitational wave signals, spectrogram and fr...

  5. Electrical resistivity of liquid noble metal alloys

    International Nuclear Information System (INIS)

    Calculations of the dependence of the electrical resistivity in liquid Ag-Au, Cu-Ag, Cu-Au binary alloys on composition are reported. The structure of the binary alloy is described as a hard sphere system. A one-parameter local pseudopotential, which incorporates s-d hybridization effects phenomenologically, is employed in the resistivity calculation. A reasonable agreement with experimental trends is observed in cases where experimental information is available. (author)

  6. The third post-Newtonian gravitational waveforms for compact binary systems in general orbits: instantaneous terms

    CERN Document Server

    Mishra, Chandra Kant; Iyer, Bala R

    2015-01-01

    We compute the instantaneous contributions to the spherical harmonic modes of gravitational waveforms from compact binary systems in general orbits up to the third post-Newtonian order. We further extend these results for compact binaries in quasi-elliptical orbits using the 3PN quasi-Keplerian representation of the conserved dynamics of compact binaries in eccentric orbits. Using the multipolar post-Minkowskian formalism, starting from the different mass and current type multipole moments, we compute the spin weighted spherical harmonic decomposition of the instantaneous part of the gravitational waveform. These are terms which are functions of the retarded time and do not depend on the history of the binary evolution. Together with the hereditary part, which depends on the binary's dynamical history, these waveforms form the basis for construction of accurate templates for the detection of gravitational wave signals from binaries moving in quasi-elliptical orbits.

  7. On the Physical Processes in Contact Binary Systems

    Institute of Scientific and Technical Information of China (English)

    Run-Qian Huang; Han-Feng Song; Shao-Lan Bi

    2007-01-01

    Three important physical processes occurring in contact binary systems are studied.The first one is the effect of spin, orbital rotation and tide on the structure of the components,which includes also the effect of meridian circulation on the mixing of the chemical elements in the components. The second one is the mass and energy exchange between the components.To describe the energy exchange, a new approach is introduced based on the understanding that the exchange is due to the release of the potential, kinetic and thermal energy of the exchanged mass. The third is the loss of mass and angular momentum through the outer Lagrangian point. The rate of mass loss and the angular momentum carried away by the lost mass are discussed. To show the effects of these processes, we follow the evolution of a binary system consisting of a 12M⊙ and a 5M⊙ star with mass exchange between the components and mass loss via the outer Lagrangian point, both with and without considering the effects of rotation and tide. The result shows that the effect of rotation and tide advances the start of the semi-detached and the contact phases, and delays the end of the hydrogen-burning phase of the primary. Furthermore, it can change not only the occurrence of mass and angular momentum loss via the outer Lagrangian point, but also the contact or semi-contact status of the system. Thus, this effect can result in the special phenomenon of short-term variations occurring over a slow increase of the orbital period. The occurrence of mass and angular momentum loss via the outer Lagrangian point can affect the orbital period of the system significantly, but this process can be influenced, even suppressed out by the effect of rotation and tide. The mass and energy exchange occurs in the common envelope. The net result of the mass exchange process is a mass transfer from the primary to the secondary during the whole contact phase.

  8. The Effect of Novel Binary Accelerator System on Properties of Vulcanized Natural Rubber

    Directory of Open Access Journals (Sweden)

    Moez Kamoun

    2009-01-01

    Full Text Available The mechanical properties, curing characteristics, and swelling behaviour of vulcanized natural rubber with a novel binary accelerator system are investigated. Results indicate that the mechanical properties were improved. Crosslinking density of vulcanized natural rubber was measured by equilibrium swelling method. As a result, the new binary accelerator was found to be able to improve both cure rate and crosslinking density. Using the numerical analysis of test interaction between binary accelerator and operational modelling of vulcanization-factors experiments, it can be concluded that the interaction (Cystine, N-cyclohexyl-2-benzothiazyl sulfenamide was significant and the optimum value of binary accelerator was suggested, respectively, at levels 0 and +1.

  9. An Accretion Disc Model For Eclipsing Binary System: AV Del

    CERN Document Server

    Ghoreyshi, Sayyed Mohammad Reza; Salehi, Fatemeh

    2008-01-01

    We investigate the light and radial-velocity curves of the eclipsing binary AV Del. Using the most new version of Wilson & Van Hamme (2003) code, the absolute elements, fundamental orbital and physical parameters of the system are determined. Then, using the new SHELLSPEC code, we study and present an accretion disc model for the system. We found AV Del is a semi-detached system which has an accretion disc around the primary star. By combining the radial-velocity and light curve analysis, we derive accurate absolute masses for the components of M1=1.449 Msun and M2 =0.687 Msun and radii of R1=2.61 Rsun and R2=4.21 Rsun as well as effective temperatures of T1=6000 K and T2= 4281 K for the primary and the secondary, respectively. Also, we derived a temperature of T=5700 K for the disc. Finally, our results are compared with those of previous authors.

  10. Binary polypeptide system for permanent and oriented protein immobilization

    Directory of Open Access Journals (Sweden)

    Bailes Julian

    2010-05-01

    Full Text Available Abstract Background Many techniques in molecular biology, clinical diagnostics and biotechnology rely on binary affinity tags. The existing tags are based on either small molecules (e.g., biotin/streptavidin or glutathione/GST or peptide tags (FLAG, Myc, HA, Strep-tag and His-tag. Among these, the biotin-streptavidin system is most popular due to the nearly irreversible interaction of biotin with the tetrameric protein, streptavidin. The major drawback of the stable biotin-streptavidin system, however, is that neither of the two tags can be added to a protein of interest via recombinant means (except for the Strep-tag case leading to the requirement for chemical coupling. Results Here we report a new immobilization system which utilizes two monomeric polypeptides which self-assemble to produce non-covalent yet nearly irreversible complex which is stable in strong detergents, chaotropic agents, as well as in acids and alkali. Our system is based on the core region of the tetra-helical bundle known as the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex. This irreversible protein attachment system (IPAS uses either a shortened syntaxin helix and fused SNAP25-synaptobrevin or a fused syntaxin-synaptobrevin and SNAP25 allowing a two-component system suitable for recombinant protein tagging, capture and immobilization. We also show that IPAS is suitable for use with traditional beads and chromatography, planar surfaces and Biacore, gold nanoparticles and for protein-protein interaction in solution. Conclusions IPAS offers an alternative to chemical cross-linking, streptavidin-biotin system and to traditional peptide affinity tags and can be used for a wide range of applications in nanotechnology and molecular sciences.

  11. Creation of an anti-imaging system using binary optics.

    Science.gov (United States)

    Wang, Haifeng; Lin, Jian; Zhang, Dawei; Wang, Yang; Gu, Min; Urbach, H P; Gan, Fuxi; Zhuang, Songlin

    2016-01-01

    We present a concealing method in which an anti-point spread function (APSF) is generated using binary optics, which produces a large-scale dark area in the focal region that can hide any object located within it. This result is achieved by generating two identical PSFs of opposite signs, one consisting of positive electromagnetic waves from the zero-phase region of the binary optical element and the other consisting of negative electromagnetic waves from the pi-phase region of the binary optical element. PMID:27620068

  12. Investigations of linear contraction and shrinkage stresses development in hypereutectic al-si binary alloys

    Directory of Open Access Journals (Sweden)

    J. Mutwil

    2009-07-01

    Full Text Available Shrinkage phenomena during solidification and cooling of hypereutectic aluminium-silicon alloys (AlSi18, AlSi21 have been examined. A vertical shrinkage rod casting with circular cross-section (constant or fixed: tapered has been used as a test sample. Two type of experiments have been conducted: 1 on development of the test sample linear dimension changes (linear expansion/contraction, 2 on development of shrinkage stresses in the test sample. By the linear contraction experiments the linear dimension changes of the test sample and the metal test mould as well a temperature in six points of the test sample have been registered. By shrinkage stresses examination a shrinkage tension force and linear dimension changes of the test sample as well a temperature in three points of the test sample have been registered. Registered time dependences of the test bar and the test mould linear dimension changes have shown, that so-called pre-shrinkage extension has been mainly by mould thermal extension caused. The investigation results have shown that both: the linear contraction as well as the shrinkage stresses development are evident dependent on metal temperature in a warmest region the sample (thermal centre.

  13. A spectroscopic and proper motion search of SDSS: Red subdwarfs in binary systems

    CERN Document Server

    Zhang, Z H; Burningham, B; Jones, H R A; Galvez-Ortiz, M C; Catalan, S; Smart, R L; Lepine, S; Clarke, J R A; Pavlenko, Ya V; Murray, D N; Kuznetsov, M K; Day-Jones, A C; Gomes, J; Marocco, F; Sipocz, B

    2013-01-01

    Red subdwarfs in binary systems are crucial for both model calibration and spectral classification. We search for red subdwarfs in binary systems from a sample of high proper motion objects with SDSS spectroscopy. We present here discoveries from this search, as well as highlighting several additional objects of interest. We find thirty red subdwarfs in wide binary systems including: two with spectral type of esdM5.5, six companions to white dwarfs and three carbon enhanced red subdwarfs with normal red subdwarf companions. Fifteen red subdwarfs in our sample are partially resolved close binary systems. With this binary sample, we estimate the low limit of the red subdwarf binary fraction of ~ 10%. We find that the binary fraction goes down with decreasing masses and metallicities of red subdwarfs. A spectroscopic esdK7 subdwarf + white dwarf binary candidate is also reported. Thirty new M subdwarfs have spectral type of >M6 in our sample. We also derive relationships between spectral types and absolute magni...

  14. Escape dynamics in a binary system of interacting galaxies

    CERN Document Server

    Zotos, Euaggelos E

    2016-01-01

    The escape dynamics in an analytical gravitational model which describes the motion of stars in a binary system of interacting dwarf spheroidal galaxies is investigated in detail. We conduct a numerical analysis distinguishing between regular and chaotic orbits as well as between trapped and escaping orbits, considering only unbounded motion for several energy levels. In order to distinguish safely and with certainty between ordered and chaotic motion, we apply the Smaller ALingment Index (SALI) method. It is of particular interest to locate the escape basins through the openings around the collinear Lagrangian points $L_1$ and $L_2$ and relate them with the corresponding spatial distribution of the escape times of the orbits. Our exploration takes place both in the configuration $(x,y)$ and in the phase $(x,\\dot{x})$ space in order to elucidate the escape process as well as the overall orbital properties of the galactic system. Our numerical analysis reveals the strong dependence of the properties of the con...

  15. Marginally low mass ratio close binary system V1191 Cyg

    CERN Document Server

    Ulas, B; Keskin, V; Kose, O; Yakut, K

    2011-01-01

    In this study, we present photometric and spectroscopic variations of the extremely small mass ratio ($q\\simeq 0.1$) late-type contact binary system \\astrobj{V1191 Cyg}. The parameters for the hot and cooler companions have been determined as $M_\\textrm{h}$ = 0.13 (1) $M_{\\odot}$, $M_\\textrm{c}$ = 1.29 (8) $M_{\\odot}$, $R_\\textrm{h}$ = 0.52 (15) $R_{\\odot}$, $R_\\textrm{c}$ = 1.31 (18) $R_{\\odot}$, $L_\\textrm{h}$ = 0.46 (25) $L_{\\odot}$, $L_\\textrm{c}$ = 2.71 (80) $L_{\\odot}$, the separation of the components is $a$= 2.20(8) $R_{\\odot}$ and the distance of the system is estimated as 278(31) pc. Analyses of the times of minima indicates a period increase of $\\frac{dP}{dt}=1.3(1)\\times 10^{-6}$ days/yr that reveals a very high mass transfer rate of $\\frac{dM}{dt}=2.0(4)\\times 10^{-7}$$M_{\\odot}$/yr from the less massive component to the more massive one. New observations show that the depths of the minima of the light curve have been interchanged.

  16. WZ CYGNI: A MARGINAL CONTACT BINARY IN A TRIPLE SYSTEM?

    International Nuclear Information System (INIS)

    We present new multiband CCD photometry for WZ Cyg made on 22 nights in two observing seasons of 2007 and 2008. Our light-curve synthesis indicates that the system is in poor thermal contact with a fill-out factor of 4.8% and a temperature difference of 1447 K. Including our 40 timing measurements, a total of 371 times of minimum light spanning more than 112 yr were used for a period study. Detailed analysis of the O-C diagram showed that the orbital period has varied by a combination of an upward parabola and a sinusoid. The upward parabola means continuous period increase and indicates that some stellar masses are thermally transferred to the more massive primary star at a rate of about 5.80 x 10-8 Msun yr-1. The sinusoidal variation with a period of 47.9 yr and a semi-amplitude of 0.008 days can most likely be interpreted as the light-travel-time effect due to the existence of a low-mass M-type tertiary companion with a projected mass of M3sin i3 = 0.26 Msun. We examined the evolutionary status of WZ Cyg from the absolute dimensions of the eclipsing pair. It belongs to the marginal contact binary systems before the broken contact phase, consisting of a massive primary star with spectral type F4 and a secondary star with type K1.

  17. The dynamical importance of binary systems in young massive star clusters

    CERN Document Server

    de Grijs, Richard; Geller, Aaron M

    2015-01-01

    Characterization of the binary fractions in star clusters is of fundamental importance for many fields in astrophysics. Observations indicate that the majority of stars are found in binary systems, while most stars with masses greater than $0.5 M_\\odot$ are formed in star clusters. In addition, since binaries are on average more massive than single stars, in resolved star clusters these systems are thought to be good tracers of (dynamical) mass segregation. Over time, dynamical evolution through two-body relaxation will cause the most massive objects to migrate to the cluster center, while the relatively lower-mass objects remain in or migrate to orbits at greater radii. This process will globally dominate a cluster's stellar distribution. However, close encounters involving binary systems may disrupt `soft' binaries. This process will occur more frequently in a cluster's central, dense region than in its periphery, which may mask the effects of mass segregation. Using high resolution Hubble Space Telescope o...

  18. MILLIONS OF MULTIPLES: DETECTING AND CHARACTERIZING CLOSE-SEPARATION BINARY SYSTEMS IN SYNOPTIC SKY SURVEYS

    Energy Technology Data Exchange (ETDEWEB)

    Terziev, Emil; Law, Nicholas M. [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada); Arcavi, Iair [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Baranec, Christoph; Bui, Khanh; Dekany, Richard G.; Kulkarni, S. R.; Riddle, Reed; Tendulkar, Shriharsh P. [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Bloom, Joshua S. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Burse, Mahesh P.; Chorida, Pravin; Das, H. K.; Punnadi, Sujit; Ramaprakash, A. N. [Inter-University Centre for Astronomy and Astrophysics, Ganeshkhind, Pune 411007 (India); Kraus, Adam L. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Nugent, Peter [Computational Cosmology Center, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Ofek, Eran O. [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel); Sullivan, Mark, E-mail: emil.terziev@utoronto.ca [Department of Physics (Astrophysics), University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)

    2013-06-01

    The direct detection of binary systems in wide-field surveys is limited by the size of the stars' point-spread functions (PSFs). A search for elongated objects can find closer companions, but is limited by the precision to which the PSF shape can be calibrated for individual stars. Based on a technique from weak-lensing analysis, we have developed the BinaryFinder algorithm to search for close binaries by using precision measurements of PSF ellipticity across wide-field survey images. We show that the algorithm is capable of reliably detecting binary systems down to Almost-Equal-To 1/5 of the seeing limit, and can directly measure the systems' position angles, separations, and contrast ratios. To verify the algorithm's performance we evaluated 100,000 objects in Palomar Transient Factory (PTF) wide-field-survey data for signs of binarity, and then used the Robo-AO robotic laser adaptive optics system to verify the parameters of 44 high-confidence targets. We show that BinaryFinder correctly predicts the presence of close companions with a <11% false-positive rate, measures the detected binaries' position angles within 1 Degree-Sign to 4 Degree-Sign (depending on signal-to-noise ratio and separation), and separations within 25%, and weakly constrains their contrast ratios. When applied to the full PTF data set, we estimate that BinaryFinder will discover and characterize {approx}450,000 physically associated binary systems with separations <2 arcsec and magnitudes brighter than m{sub R} = 18. New wide-field synoptic surveys with high sensitivity and sub-arcsecond angular resolution, such as LSST, will allow BinaryFinder to reliably detect millions of very faint binary systems with separations as small as 0.1 arcsec.

  19. In-situ high-energy X-ray diffraction investigation on stress-induced martensitic transformation in Ti-Nb binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chang, L. L.; Wang, Y. D.; Ren, Y.

    2016-01-10

    Microstructure evolution, mechanical behaviors of cold rolled Ti-Nb alloys with different Nb contents subjected to different heat treatments were investigated. Optical microstructure and phase compositions of Ti-Nb alloys were characterized using optical microscopy and X-ray diffractometre, while mechanical behaviors of Ti-Nb alloys were examined by using tension tests. Stress-induced martensitic transformation in a Ti-30. at%Nb binary alloy was in-situ explored by synchrotron-based high-energy X-ray diffraction (HE-XRD). The results obtained suggested that mechanical behavior of Ti-Nb alloys, especially Young's modulus was directly dependent on chemical compositions and heat treatment process. According to the results of HE-XRD, α"-V1 martensite generated prior to the formation of α"-V2 during loading and a partial reversible transformation from α"-V1 to β phase was detected while α"-V2 tranformed to β completely during unloading.

  20. The photometric investigation of the newly discovered W UMa type binary system GSC 03122-02426

    Science.gov (United States)

    Zhou, X.; Qian, S.-B.; He, J.-J.; Zhang, J.; Zhang, B.

    2016-10-01

    The B V Rc Ic bands light curves of the newly discovered binary system GSC 03122-02426 are obtained and analyzed using the Wilson-Devinney (W-D) code. The solutions suggest that the mass ratio of the binary system is q = 2.70 and the less massive component is 422 K hotter than the more massive one. We conclude that GSC 03122-02426 is a W-subtype shallow contact (with a contact degree of f = 15.3 %) binary system. It may be a newly formed contact binary system which is just under geometrical contact and will evolve to be a thermal contact binary system. The high orbital inclination (i = 81 .6∘) implies that GSC 03122-02426 is a total eclipsing binary system and the photometric parameters obtained by us are quite reliable. We also estimate the absolute physical parameters of the two components in GSC 03122-02426, which will provide fundamental information for the research of contact binary systems. The formation and evolutionary scenario of GSC 03122-02426 is discussed.

  1. The photometric investigation of the newly discovered W UMa type binary system GSC 03122-02426

    CERN Document Server

    Zhou, X; He, J -J; Zhang, J; Zhang, B

    2016-01-01

    The $B$ $V$ $R_c$ $I_c$ bands light curves of the newly discovered binary system \\astrobj{GSC 03122-02426} are obtained and analyzed using the Wilson-Devinney (W-D) code. The solutions suggest that the mass ratio of the binary system is $q = 2.70$ and the less massive component is $422K$ hotter than the more massive one. We conclude that \\astrobj{GSC 03122-02426} is a W-subtype shallow contact (with a contact degree of $f = 15.3\\,\\%$) binary system. It may be a newly formed contact binary system which is just under geometrical contact and will evolve to be a thermal contact binary system. The high orbital inclination ($i = 81.6^{\\circ}$) implies that \\astrobj{GSC 03122-02426} is a total eclipsing binary system and the photometric parameters obtained by us are quite reliable. We also estimate the absolute physical parameters of the two components in \\astrobj{GSC 03122-02426}, which will provide fundamental information for the research of contact binary systems. The formation and evolutionary scenario of \\astro...

  2. Phase equilibria and thermodynamic functions for Ag–Hg and Cu–Hg binary systems

    International Nuclear Information System (INIS)

    Highlights: ► The thermodynamic properties of Ag–Hg and Cu–Hg are explored in order to facilitate dental materials design. ► A self-consistent set of thermodynamic parameters is obtained. ► The experimental information can be well reproduced by the optimized thermodynamic data. - Abstract: In order to facilitate the computational design of new amalgams for novel dental alloys, the phase equilibria, phase diagrams and thermodynamic functions for Ag–Hg and Cu–Hg binary systems are explored in this work, based on the CALPHAD framework and experimental characterizations. The Gibbs free energies of the solution phases as well as the stoichiometric phases are calculated, with the aid of enthalpies of mixing, activities, enthalpies of formation, and phase equilibrium data. The thermodynamic descriptions provided in this work enable the stabilities of each phase at various temperatures and compositions to be well described, which contribute to the establishment of a general database to design novel metallic dental materials.

  3. Revisit on "Ruling out chaos in compact binary systems"

    CERN Document Server

    Wu, Xin; 10.1103/PhysRevD.76.124004

    2010-01-01

    Full general relativity requires that chaos indicators should be invariant in various spacetime coordinate systems for a given relativistic dynamical problem. On the basis of this point, we calculate the invariant Lyapunov exponents (LEs) for one of the spinning compact binaries in the conservative second post-Newtonian (2PN) Lagrangian formulation without the dissipative effects of gravitational radiation, using the two-nearby-orbits method with projection operations and with coordinate time as an independent variable. It is found that the actual source leading to zero LEs in one paper [J. D. Schnittman and F. A. Rasio, Phys. Rev. Lett. 87, 121101 (2001)] but to positive LEs in the other [N. J. Cornish and J. Levin, Phys. Rev. Lett. 89, 179001 (2002)] does not mainly depend on rescaling, but is due to two slightly different treatments of the LEs. It takes much more CPU time to obtain the stabilizing limit values as reliable values of LEs for the former than to get the slopes (equal to LEs) of the fit lines f...

  4. Magnetised winds in single and binary star systems

    Science.gov (United States)

    Johnstone, Colin

    2016-07-01

    Stellar winds are fundamentally important for the stellar magnetic activity evolution and for the immediate environment surrounding their host stars. Ionised winds travel at hundreds of km/s, impacting planets and clearing out large regions around the stars called astropheres. Winds influence planets in many ways: for example, by compressing the magnetosphere and picking up atmospheric particles, they can cause significant erosion of a planetary atmosphere. By removing angular momentum, winds cause the rotation rates of stars to decrease as they age. This causes the star's magnetic dynamo to decay, leading to a significant decay in the star's levels of X-ray and extreme ultraviolet emission. Despite their importance, little is currently known about the winds of other Sun-like stars. Their small mass fluxes have meant that no direct detections have so far been possible. What is currently known has either been learned indirectly or through analogies with the solar wind. In this talk, I will review what is known about the properties and evolution of the winds of other Sun-like stars. I will also review wind dynamics in binary star systems, where the winds from both stars impact each other, leading to shocks and compression regions.

  5. The two-dimensional alternative binary L-J system: liquid-gas phase diagram

    Institute of Scientific and Technical Information of China (English)

    张陟; 陈立溁

    2003-01-01

    A two-dimensional (2D) binary system without considering the Lennard-Jones (L-J) potential has been studied by using the Collins model. In this paper, we introduce the L-J potential into the 2D binary system and consider the existence of the holes that are called the "molecular fraction". The liquid-gas phase diagram of the 2D alternative binary L-J system is obtained. The results are quite analogous to the behaviour of 3D substances.

  6. Binary Asteroid Systems: Tidal End States and Estimates of Material Properties

    CERN Document Server

    Taylor, Patrick A

    2011-01-01

    The locations of the fully despun, double synchronous end states of tidal evolution are derived for spherical components. With the exception of nearly equal-mass binaries, binary asteroid systems are in the midst of lengthy tidal evolutions, far from their fully synchronous tidal end states. Calculations of material strength indicate that binaries in the main belt with 100-km-scale primary components are consistent with being made of monolithic or fractured rock as expected for binaries likely formed from sub-catastrophic impacts in the early solar system. To tidally evolve in their dynamical lifetime, near-Earth binaries with km-scale primaries or smaller must be much weaker mechanically than their main-belt counterparts even if formed in the main belt prior to injection into the near-Earth region. Small main-belt binaries with primary components less than 10 km in diameter, depending on their ages, could either be as strong as large main-belt binaries or as weak as near-Earth binaries because the inherent u...

  7. EL CVn-type binaries - Discovery of 17 helium white dwarf precursors in bright eclipsing binary star systems

    CERN Document Server

    Maxted, P F L; Heber, U; Geier, S; Wheatley, P J; Marsh, T R; Breedt, E; Sebastian, D; Faillace, G; Owen, C; Pulley, D; Smith, D; Kolb, U; Haswell, C A; Southworth, J; Anderson, D R; Smalley, B; Cameron, A Collier; Hebb, L; Simpson, E K; West, R G; Bochinski, J; Busuttil, R; Hadigal, S

    2013-01-01

    The star 1SWASP J024743.37-251549.2 was recently discovered to be a binary star in which an A-type dwarf star eclipses the remnant of a disrupted red giant star (WASP0247-25B). The remnant is in a rarely-observed state evolving to higher effective temperatures at nearly constant luminosity prior to becoming a very low-mass white dwarf composed almost entirely of helium, i.e., it is a pre-He-WD. We have used the WASP photometric database to find 17 eclipsing binary stars with orbital periods P=0.7 to 2.2 days with similar lightcurves to 1SWASP J024743.37-251549.2. The only star in this group previously identified as a variable star is the brightest one, EL CVn, which we adopt as the prototype for this class of eclipsing binary star. The characteristic lightcurves of EL CVn-type stars show a total eclipse by an A-type dwarf star of a smaller, hotter star and a secondary eclipse of comparable depth to the primary eclipse. We have used new spectroscopic observations for 6 of these systems to confirm that the comp...

  8. Corrosion of copper alloys in sulphide containing district heting systems

    DEFF Research Database (Denmark)

    Thorarinsdottir, R.I.; Maahn, Ernst Emanuel

    1999-01-01

    Copper and some copper alloys are prone to corrosion in sulphide containing geothermal water analogous to corrosion observed in district heating systems containing sulphide due to sulphate reducing bacteria. In order to study the corrosion of copper alloys under practical conditions a test...... was carried out at four sites in the Reykjavik District Heating System. The geothermal water chemistry is different at each site. The corrosion rate and the amount and chemical composition of deposits on weight loss coupons of six different copper alloys are described after exposure of 12 and 18 months...

  9. Cancer-specific binary expression system activated in mice by bacteriophage HK022 Integrase.

    Science.gov (United States)

    Elias, Amer; Spector, Itay; Sogolovsky-Bard, Ilana; Gritsenko, Natalia; Rask, Lene; Mainbakh, Yuli; Zilberstein, Yael; Yagil, Ezra; Kolot, Mikhail

    2016-01-01

    Binary systems based on site-specific recombination have been used for tumor specific transcription targeting of suicide genes in animal models. In these binary systems a site specific recombinase or integrase that is expressed from a tumor specific promoter drives tumor specific expression of a cytotoxic gene. In the present study we developed a new cancer specific binary expression system activated by the Integrase (Int) of the lambdoid phage HK022. We demonstrate the validity of this system by the specific expression of a luciferase (luc) reporter in human embryonic kidney 293T (HEK293T) cells and in a lung cancer mouse model. Due to the absence viral vectors and of cytotoxicity the Int based binary system offers advantages over previously described counterparts and may therefore be developed into a safer cancer cell killing system. PMID:27117628

  10. Analytic calculation of formation enthalpies directly from interatomic potentials for binary and ternary refractory metal systems

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An analytic method is proposed to calculate the formation enthalpy directly from empirical n-body potential and applied to the binary and ternary systems consisting of the refractory metals Mo, Nb, Ta and W. It turns out that the calculated enthalpies are in overall agreement with experimental observations and some other theoretical calculations. Interestingly, it shows that the formation enthalpies of the ternary systems are significantly affected by those of the constituent binary systems.

  11. Near-Infrared Polarimetry of the GG Tauri A Binary System

    CERN Document Server

    Itoh, Yoichi; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Hashimoto, Jun; Abe, Lyu; Brandner, Wolfgang; Brandt, Timothy D; Carson, Joseph C; Egner, Sebastian; Feldt, Markus; Grady, Carol A; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S; Henning, Thomas; Hodapp, Klaus W; Ishii, Miki; Iye, Masanori; Janson, Markus; Kandori, Ryo; Knapp, Gillian R; Kuzuhara, Masayuki; Kwon, Jungmi; Matsuo, Taro; McElwain, Michael W; Miyama, Shoken; Morino, Jun-Ichi; Moro-Martin, Amaya; Nishimura, Tetsuo; Pyo, Tae-Soo; Serabyn, Eugene; Suenaga, Takuya; Suto, Hiroshi; Suzuki, Ryuji; Takahashi, Yasuhiro H; Takato, Naruhisa; Terada, Hiroshi; Thalmann, Christian; Tomono, Daigo; Turner, Edwin L; Watanabe, Makoto; Wisniewski, John; Yamada, Toru; Mayama, Satoshi; Currie, Thayne; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

    2015-01-01

    A high angular resolution near-infrared polarized-intensity image of the GG Tau A binary system was obtained with the Subaru Telescope. The image shows the circumbinary disk scattering the light from the central binary. The azimuthal profile of the polarized intensity of the circumbinary disk is roughly reproduced by a simple disk model with the Henyey-Greenstein function and the Rayleigh function, indicating small dust grains at the surface of the disk. Combined with a previous observation of the circumbinary disk, our image indicates that the gap structure in the circumbinary disk orbits anti-clockwise, while material in the disk orbit clockwise. We propose a shadow of material located between the central binary and the circumbinary disk. The separations and position angles of the stellar components of the binary in the past 20 years are consistent with the binary orbit with a = 33.4 AU and e = 0.34.

  12. Evolution of Intermediate and Low Mass Binary Systems

    Energy Technology Data Exchange (ETDEWEB)

    Eggleton, P P

    2005-10-25

    There are a number of binaries, fairly wide and with one or even two evolved giant components, that do not agree very well with conventional stellar evolution: the secondaries are substantially larger (oversized) than they should be because their masses are quite low compared with the primaries. I discuss the possibility that these binaries are former triples, in which a merger has occurred fairly recently in a short-period binary sub-component. Some mergers are expected, and may follow a phase of contact evolution. I suggest that in contact there is substantial transfer of luminosity between the components due to differential rotation, of the character observed by helioseismology in the Sun's surface convection zone.

  13. Unusual response of the binary V-2Si alloy to neutron irradiation in FFTF at 430-600{degrees}C

    Energy Technology Data Exchange (ETDEWEB)

    Ohnuki, S.; Konoshita, H.; Takahaski, H. [Hokkaido Univ., Sapparo (Japan); Garner, F.A. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1996-04-01

    When V-2Si was irradiated in FFTF at 430, 500 and 600C to doses as high as 80 dpa, a very unusual swelling response was observed in which the swelling appeared to saturate rather quickly at {approx}35% at 430 and 540C, but approached this swelling same level much more slowly at 600C. The possible causes of this phenomenon are discussed as well as the implications of these findings on the swelling behavior of other high swelling vanadium binary alloys.

  14. Chandra resolves the T Tauri binary system RW Aur

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Stephen L. [CASA, University of Colorado, Boulder, CO 80309-0389 (United States); Güdel, Manuel, E-mail: stephen.skinner@colorado.edu, E-mail: manuel.guedel@univie.ac.at [Department of Astrophysics, University of Vienna, Türkenschanzstr. 17, A-1180 Vienna (Austria)

    2014-06-20

    RW Aur is a multiple T Tauri system consisting of an early-K type primary (A) and a K5 companion (B) at a separation of 1.''4. RW Aur A drives a bipolar optical jet that is well characterized optically. We present results of a sensitive Chandra observation whose primary objective was to search for evidence of soft extended X-ray emission along the jet, as has been seen for a few other nearby T Tauri stars. The binary is clearly resolved by Chandra and both stars are detected as X-ray sources. The X-ray spectra of both stars reveal evidence for cool and hot plasma. Surprisingly, the X-ray luminosity of the less-massive secondary is at least twice that of the primary and is variable. The disparity is attributed to the primary whose X-ray luminosity is at the low end of the range for classical T Tauri stars of similar mass based on established correlations. Deconvolved soft-band images show evidence for slight outward elongation of the source structure of RW Aur A along the blueshifted jet axis inside the central arcsecond. In addition, a faint X-ray emission peak is present on the redshifted axis at an offset of 1.''2 ± 0.''2 from the star. Deprojected jet speeds determined from previous optical studies are too low to explain this faint emission peak as shock-heated jet plasma. Thus, unless flow speeds in the redshifted jet have been underestimated, other mechanisms such as magnetic jet heating may be involved.

  15. Black holes in binary stellar systems and galactic nuclei

    Science.gov (United States)

    Cherepashchuk, A. M.

    2014-04-01

    In the last 40 years, following pioneering papers by Ya B Zeldovich and E E Salpeter, in which a powerful energy release from nonspherical accretion of matter onto a black hole (BH) was predicted, many observational studies of black holes in the Universe have been carried out. To date, the masses of several dozen stellar-mass black holes (M_BH = (4{-}20) M_\\odot) in X-ray binary systems and of several hundred supermassive black holes (M_BH = (10^{6}{-}10^{10}) M_\\odot) in galactic nuclei have been measured. The estimated radii of these massive and compact objects do not exceed several gravitational radii. For about ten stellar-mass black holes and several dozen supermassive black holes, the values of the dimensionless angular momentum a_* have been estimated, which, in agreement with theoretical predictions, do not exceed the limiting value a_* = 0.998. A new field of astrophysics, so-called black hole demography, which studies the birth and growth of black holes and their evolutionary connection to other objects in the Universe, namely stars, galaxies, etc., is rapidly developing. In addition to supermassive black holes, massive stellar clusters are observed in galactic nuclei, and their evolution is distinct from that of supermassive black holes. The evolutionary relations between supermassive black holes in galactic centers and spheroidal stellar components (bulges) of galaxies, as well as dark-matter galactic haloes are brought out. The launch into Earth's orbit of the space radio interferometer RadioAstron opened up the real possibility of finally proving that numerous discovered massive and highly compact objects with properties very similar to those of black holes make up real black holes in the sense of Albert Einstein's General Relativity. Similar proofs of the existence of black holes in the Universe can be obtained by intercontinental radio interferometry at short wavelengths \\lambda \\lesssim 1 mm (the international program, Event Horizon Telescope).

  16. Direct Measurement of the Metastable Liquid Miscibility Gap in Fe-Co-Cu Ternary Alloy System

    Institute of Scientific and Technical Information of China (English)

    CAO Chong-De; Georg P.G(O)RLER

    2005-01-01

    @@ The metastable liquid-liquid phase separation in undercooled Fe-Co-Cu ternary alloy melts (XCu = 0.10-0.84;XCo:XFe = 1:3,1:1 and 3:1) is investigated by differential thermal analysis in combination with glass fluxing technique. In almost every case, the undercooling of the homogeneous alloy melt was sufficient to reach the boundary line of the submerged miscibility gap. The differential-thermal-analysis signals indicate that this separation into a (Fe, Co)-rich liquid phase L1 and a Cu-rich liquid L2 is exothermic and proceeds until the rapid solidification of the L1 phase occurs. At a given Cu concentration and with the increase of Co content, the phase separation temperatures decrease monotonically between the corresponding values of the boundary systems Fe-Cu and Co-Cu. The boundary lines of the miscibility gap, which are determined for the three quasi-binary cross-sections of the (Fe, Co)-Cu alloy system, show remarkably flat domes. The occurrence of the liquid phase separation shows an evident influence on the subsequent γ-Fe(Co, Cu)→α-Fe(Co, Cu) solid phase transformation.

  17. Microstructure Formations in the Two-Phase Region of the Binary Peritectic Organic System TRIS-NPG

    Science.gov (United States)

    Mogeritsch, Johann; Ludwig, Andreas

    2012-01-01

    In order to prepare for an onboard experiment on the International Space Station (ISS), systematic directional solidification experiments with transparent hypoperitectic alloys were carried out at different solidification rates around the critical velocity for morphological stability of both solid phases. The investigations were done in the peritectic region of the binary transparent organic TRIS-NPG system where the formation of layered structures is expected to occur. The transparent appearance of the liquid and solid phase enables real time observations of the dynamic of pattern formation during solidification. The investigations show that frequently occurring nucleation events govern the peritectic solidification morphology which occurs at the limit of morphological stability. As a consequence, banded structures lead to coupled growth even if the lateral growth is much faster compared to the growth in pulling direction.

  18. Review of candidates of binary systems with an RR Lyrae component

    CERN Document Server

    Skarka, Marek; Zejda, Miloslav; Mikulášek, Zdeněk

    2016-01-01

    We present an overview and current status of research on RR Lyrae stars in binary systems. In present days the number of binary candidates has steeply increased and suggested that multiple stellar systems with an RR Lyrae component is much higher than previously thought. We discuss the probability of their detection using various observing methods, compare recent results regarding selection effects, period distribution, proposed orbital parameters and the Blazhko effect.

  19. Gamma-rays from nebulae around binary systems containing energetic rotation powered pulsars

    OpenAIRE

    Bednarek, W.; Sitarek, J.

    2013-01-01

    We consider nebulae which are created around binary systems containing rotation powered pulsars and companion stars with strong stellar winds. It is proposed that the stellar and pulsar winds have to mix at some distance from the binary system, defined by the orbital period of the companion stars and the velocity of the stellar wind. The mixed pulsar-stellar wind expands with a specific velocity determined by the pulsar power and the mass loss rate of the companion star. Relativistic particle...

  20. The 2D Alternative Binary L-J System: Solid-Liquid Phase Diagram

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi; CHEN Li-Rong

    2002-01-01

    The Lennard-Jones potential is introduced into the Collins model and is generalized to the two-dimensionalalternative binary system. The Gibbs free energy of the binary system is calculated. According to the thermodynamicconditions of solid-liquid equilibrium, the "cigar-type" phase diagram and the phase diagram with a minimum areobtained. The results are quite analogous to the behavior of three-dimensional substances.

  1. Measurement system analysis for binary inspection: Continuous versus dichotomous measurands

    NARCIS (Netherlands)

    J. de Mast; T.P. Erdmann; W.N. van Wieringen

    2011-01-01

    We review methods for assessing the reliability of binary measurements, such as accept/reject inspection in industry. Our framework introduces two factors that are highly relevant in deciding which method to use: (1) whether a reference value (gold standard) can be obtained and (2) whether the under

  2. Migration into a Companion's Trap: Disruption of Multiplanet Systems in Binaries

    CERN Document Server

    Touma, Jihad R

    2015-01-01

    Most exoplanetary systems in binary stars are of S--type, and consist of one or more planets orbiting a primary star with a wide binary stellar companion. Gravitational forcing of a single planet by a sufficiently inclined binary orbit can induce large amplitude oscillations of the planet's eccentricity and inclination through the Kozai-Lidov (KL) instability. KL cycling was invoked to explain: the large eccentricities of planetary orbits; the family of close--in hot Jupiters; and the retrograde planetary orbits in eccentric binary systems. However, several kinds of perturbations can quench the KL instability, by inducing fast periapse precessions which stabilize circular orbits of all inclinations: these could be a Jupiter--mass planet, a massive remnant disc or general relativistic precession. Indeed, mutual gravitational perturbations in multiplanet S--type systems can be strong enough to lend a certain dynamical rigidity to their orbital planes. Here we present a new and faster process that is driven by t...

  3. Thermodynamics of ordered and disordered phases in the binary Mo-Ru system

    DEFF Research Database (Denmark)

    Kissavos, A.E.; Shallcross, Sam; Kaufman, L.;

    2007-01-01

    We have performed ab initio calculations of the mixing enthalpy for the Mo-Ru alloy system. Both completely random alloys on the fcc, bcc, and hcp lattices as well as ordered and partially ordered structures based on the hcp lattice and a sigma phase have been examined. Further, we have performed...... to ordering effects in this system. We find unusually large deviations between calculated and experimental values of the mixing enthalpy for Ru-rich hcp alloys. Our calculations indicate, in agreement with experiment, that there are ordering trends in the system. However, even under assumption of maximal...

  4. The Alpha Centauri binary system. Atmospheric parameters and element abundances

    Science.gov (United States)

    Porto de Mello, G. F.; Lyra, W.; Keller, G. R.

    2008-09-01

    Context: The α Centauri binary system, owing to its duplicity, proximity and brightness, and its components' likeness to the Sun, is a fundamental calibrating object for the theory of stellar structure and evolution and the determination of stellar atmospheric parameters. This role, however, is hindered by a considerable disagreement in the published analyses of its atmospheric parameters and abundances. Aims: We report a new spectroscopic analysis of both components of the α Centauri system, compare published analyses of the system, and attempt to quantify the discrepancies still extant in the determinations of the atmospheric parameters and abundances of these stars. Methods: The analysis is differential with respect to the Sun, based on spectra with R = 35 000 and signal-to-noise ratio ≥1000, and employed spectroscopic and photometric methods to obtain as many independent T_eff determinations as possible. We also check the atmospheric parameters for consistency against the results of the dynamical analysis and the positions of the components in a theoretical HR diagram. Results: The spectroscopic atmospheric parameters of the system are found to be T_eff = (5847 ± 27) K, [Fe/H] = +0.24 ± 0.03, log g = 4.34 ± 0.12, and ξt = 1.46 ± 0.03 km s-1, for α Cen A, and T_eff = (5316 ± 28) K, [Fe/H] = +0.25 ± 0.04, log g = 4.44 ± 0.15, and ξt = 1.28 ± 0.15 km s^-1 for α Cen B. The parameters were derived from the simultaneous excitation & ionization equilibria of Fe I and Fe II lines. T_effs were also obtained by fitting theoretical profiles to the Hα line and from photometric calibrations. Conclusions: We reached good agreement between the three criteria for α Cen A. For α Cen B the spectroscopic T_eff is ~140 K higher than the other two determinations. We discuss possible origins of this inconsistency, concluding that the presence of non-local thermodynamic equilibrium effects is a probable candidate, but we note that there is as yet no consensus on

  5. The Impact of Stellar Multiplicity on Planetary Systems, I.: The Ruinous Influence of Close Binary Companions

    CERN Document Server

    Kraus, Adam L; Huber, Daniel; Mann, Andrew W; Dupuy, Trent J

    2016-01-01

    The dynamical influence of binary companions is expected to profoundly influence planetary systems. However, the difficulty of identifying planets in binary systems has left the magnitude of this effect uncertain; despite numerous theoretical hurdles to their formation and survival, at least some binary systems clearly host planets. We present high-resolution imaging of 382 Kepler Objects of Interest (KOIs) obtained using adaptive-optics imaging and nonredundant aperture-mask interferometry (NRM) on the Keck-II telescope. Among the full sample of 506 candidate binary companions to KOIs, we super-resolve some binary systems to projected separations of 0.4; we instead only found 23 companions (a 4.6 sigma deficit), many of which must be wider pairs that are only close in projection. When the binary population is parametrized with a semimajor axis cutoff a_cut and a suppression factor inside that cutoff S_bin, we find with correlated uncertainties that inside a_cut = 47 +59/-23 AU, the planet occurrence rate in...

  6. System for ultra high vacuum made of aluminum alloys

    International Nuclear Information System (INIS)

    We have developed the system for ultra high vacuum made of aluminum alloys for proton and electron synchrotron. This is the first system for ultra high vacuum in which bakable metal seal flange and small diametral bellows of aluminum alloys have been put to practical use. The system consists of the flange protected by a CrN thin film and made of 2219-T87 alloy, the chamber made of 6063-T6 alloy, the aluminum metal gasket of Helico Flex and the bellows made of 5052 alloy. As a result of experiments at the National Laboratory for High Energy Physics (KEK), it had been confirmed that this system shows the special qualities of ultra high vacuum operation, resistance to hard radiation and baking and cooling operations. Up to now, this system has been widely used for the beam lines of the booster synchrotron utilization facility, K1, K2, linac, PI 1 and EP2-B extension of the KEK proton synchrotron. We investigate that this system is applicable to nuclear energy utilization facility and general vacuum apparatus. (author)

  7. Random alloy diffusion kinetics for the application to multicomponent alloy systems

    Science.gov (United States)

    Paul, T. R.; Belova, I. V.; Murch, G. E.

    2016-04-01

    In this paper, extensive Monte Carlo simulation results are reported on tracer and collective diffusion correlation effects in the random ternary alloy, as an example of a multicomponent alloy system. The problem of analytically describing both collective and tracer diffusion kinetics is also addressed for the random multicomponent alloy by application of a combination of the Manning theory and Holdsworth and Elliott theory. It is found that the overall results from the combined theory agree reasonably well with Monte Carlo results. This combined approach is much more accurate than Manning's approach itself and much more manageable than the almost exact, but unfortunately difficult to use, self-consistent theory of Moleko, Allnatt and Allnatt. Some relations between the Onsager phenomenological coefficients and tracer diffusion coefficients are derived and are tested with our Monte Carlo data. Good agreement is found.

  8. Solid/liquid interfacial free energies in binary systems

    Science.gov (United States)

    Nason, D.; Tiller, W. A.

    1973-01-01

    Description of a semiquantitative technique for predicting the segregation characteristics of smooth interfaces between binary solid and liquid solutions in terms of readily available thermodynamic parameters of the bulk solutions. A lattice-liquid interfacial model and a pair-bonded regular solution model are employed in the treatment with an accommodation for liquid interfacial entropy. The method is used to calculate the interfacial segregation and the free energy of segregation for solid-liquid interfaces between binary solutions for the (111) boundary of fcc crystals. The zone of compositional transition across the interface is shown to be on the order of a few atomic layers in width, being moderately narrower for ideal solutions. The free energy of the segregated interface depends primarily upon the solid composition and the heats of fusion of the component atoms, the composition difference of the solutions, and the difference of the heats of mixing of the solutions.

  9. Impact flux of asteroids and water transport to the habitable zone in binary star systems

    CERN Document Server

    Bancelin, D; Eggl, S; Dvorak, R

    2015-01-01

    By now, observations of exoplanets have found more than 50 binary star systems hosting 71 planets. We expect these numbers to increase as more than 70% of the main sequence stars in the solar neighborhood are members of binary or multiple systems. The planetary motion in such systems depends strongly on both the parameters of the stellar system (stellar separation and eccentricity) and the architecture of the planetary system (number of planets and their orbital behaviour). In case a terrestrial planet moves in the so-called habitable zone (HZ) of its host star, the habitability of this planet depends on many parameters. A crucial factor is certainly the amount of water. We investigate in this work the transport of water from beyond the snow-line to the HZ in a binary star system and compare it to a single star system.

  10. The Planet in the HR 7162 Binary System Discovered by PHASES Astrometry

    Science.gov (United States)

    Muterspaugh, Matthew W.; Lane, B. F.; Konacki, M.; Burke, B. F.; Colavita, M. M.; Shao, M.; Hartkopf, W. I.; Boss, A. P.; O'Connell, J.; Fekel, F. C.; Wiktorowicz, S. J.

    2011-01-01

    The now-completed Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) used phase-referenced long-baseline interferometry to monitor 51 binary systems with 35 micro-arcsecond measurement precision, resulting in the high-confidence detection of a planet in the HR 7162 system. The 1.5 Jupiter mass planet is in a 2 AU orbit around one of the stars, whereas the binary itself has a separation of only 19 AU. Despite the close stellar companion, this configuration is expected to be stable, based on dynamic simulations. In the context of our solar system, this is analogous to a Jovian planet just outside of Mars' orbit, with a second star at the distance of Uranus. If this configuration were present during the period of planet formation, the complex gravitational environment created by the stars would seem to disrupt planet formation mechanisms that require long times to complete (thousands of years or more). While it is possible the arrangement resulted from the planet being formed in another environment (a single star or wider binary) after which the system reached its current state via dynamic interactions (star-planet exchange with a binary, or the binary orbit shrinking by interacting with a passing star), the frequency of such interactions is very low. Because the PHASES search only had the sensitivity to rule out Jovian mass companions in 11 of our 51 systems, yet one such system was found, the result indicates either extreme luck or that there is a high frequency of 20 AU binaries hosting planets. The latter interpretation is supported by previous detections of planets in 5-6 additional 20 AU binaries in other surveys (though with less control over the statistics for determining frequency of occurrence). Thus, there is observational support suggesting that a mechanism for rapid Jovian planet formation occurs in nature.

  11. Investigation of Interdiffusion Behavior in the Mo-Zr Binary System via Diffusion Couple Studies

    Energy Technology Data Exchange (ETDEWEB)

    A. Paz y Puente; J. Dickson; D.D. Keiser, Jr.; Y.H. Sohn

    2014-03-01

    Zirconium has recently garnered attention for use as a diffusion barrier between U–Mo metallic nuclear fuels and Al alloy cladding. In order to gain a fundamental understanding of the diffusional interactions, the interdiffusion behavior in the binary Mo–Zr system was investigated via solid-to-solid diffusion couples annealed in the temperature range of 750 to 1050 degrees C. A combination of scanning electron microscopy, X-ray energy dispersive spectroscopy, and electron probe microanalysis were used to examine the microstructure and concentration profiles across the interdiffusion zone. A large __-Zr (cI2) solid solution layer and a thin (approximately 1–2 um) layer of Mo2Zr (cF24) developed in all couples. Parabolic growth constants and concentration dependent interdiffusion coefficients were calculated for the Mo2Zr and Zr solid solution phases, respectively. The pre-exponential factor and activation energy for growth of the Mo2Zr phase were determined to be approximately 6.5 × 10- 15 m2/s and 90 kJ/mol, respectively. The interdiffusion coefficient in ___-Zr solid solution decreased with an increase in Mo concentration. Both the pre-exponential factors (2 × 10- 8 m2/s at 2 at.% Mo to near 5 × 10- 8 m2/s at 9 at.% Mo) and activation energies (140 kJ/mol at 2 at.% Mo to approximately 155 kJ/mol at 9 at.% Mo) of interdiffusion coefficients were determined to increase with an increase in Mo concentration.

  12. Thermodynamic assessment of Au-La and Au-Er binary systems

    Energy Technology Data Exchange (ETDEWEB)

    Dong, H.Q., E-mail: hongqun.dong@aalto.fi [Department of Electronics, Aalto University School of Science and Technology, FIN-02601 Espoo (Finland); Tao, X.M. [Key Laboratory of New Processing Technology for Nonferrous Metals and Materials of Ministry of Education, Department of Physics, Guangxi University, Nanning 530004 (China); Liu, H.S. [Scientific Center of Phase Diagrams and Materials Design, Central South University, Changsha, Hunan 410083 (China); Laurila, T.; Paulastro-Kroeckel, M. [Department of Electronics, Aalto University School of Science and Technology, FIN-02601 Espoo (Finland)

    2011-03-31

    Research highlights: > It's the first time that Au-La and Au-Er binary systems were thermodynamically assessed since 1985. > Besides, in the present work, the ab initio approach has been employed to calculate the formation enthalpies of the IMCs involved in Au-Er and Au-La binary systems, and then, by combining with all of the available experimental information, these two-system were thermodynamically optimized via CALPHAD method. Therefore, a more reliable thermodynamic description has been obtained for these systems. - Abstract: Phase relationships in Au-La and Au-Er binary systems have been thermodynamically assessed by using the CALPHAD technique. The existing thermodynamic descriptions of the systems were improved by incorporating the ab initio calculated enthalpies of formation of the intermetallic compounds, except for the Au{sub 51}La{sub 14} and Au{sub 10}Er{sub 7} phases. All the binary intermetallic compounds were treated as stoichiometric phases, while the solution phases, including liquid, fcc, bcc, and dhcp, were treated as substitutional solution phases and the excess Gibbs energies were formulated with Redlich-Kister polynomial function. As a result, two self-consist thermodynamic data sets for describing the Au-La and Au-Er binary systems were obtained.

  13. Thermodynamic description of the Ga-Yb binary system

    Directory of Open Access Journals (Sweden)

    Idbenali M.

    2013-07-01

    Full Text Available Pure gallium metal and many gallium based alloys and intermetallic compounds have extensive technological applications and fundamental interest. Gallium is used as a doping component in electronic devices (as in transistors or photovoltaic cells [1]. The development of multi-alloy material depends nowfor most of them on preliminary numerical simulations. Such simulations are only useful when accurate thermodynamic databases are available. Such databases are developed by the CALPHAD (CALculation of PHAse Diagram method on a basis of experimental thermodynamic and phase diagram measurements. The excess term of the Gibbs energy of the liquid phase was assessed with the recent exponential temperature dependence of the interaction energies by Kaptay [2–4] and compared with the Redlich-Kister [5] polynomial equation results. The calculations based on the thermodynamic modelling and optimisation are in good agreement with the phase diagram data availablein the literature.

  14. Metallicity dependence of Type Ib/c and IIb supernova progenitors in binary systems

    Science.gov (United States)

    Yoon, Sung-CHul

    2015-08-01

    Type Ib/c supernovae (SNe Ib/c) are characterized by the lack of prominent hydrogen lines in the spectra, implying that their progenitors have lost most of their hydrogen envelopes by the time of the iron core collapse. Binary interactions provide an important evolutionary chanel for SNe Ib/c, and recent observations indicate that the inferred ejecta masses of SNe Ibc are more consistent with the prediction of the binary scenario than that of the single star scenario that invokes mass loss as the key evolutionary factor for SNe Ib/c progenitors. So far, theoretical predictions on the detailed properties of SNe Ib/c progenitors in binary systems have been made mostly with models using solar metallicity. However, unlike the single star scenario, where SNe Ib/c are expected only for sufficiently high metallicity, hydrogen-deficent SN progenitors can be produced via binary interactions at any metallicity. In this talk, I will discuss theoretical predictions on the metallicity dependence of the SNe Ib/c progenitor structure, based on evolutionary models of massive binary stars. Sepefically, I will address how the ejecta masses of SNe Ib and Ic and the ratio of SN Ib/c to SN IIb as well as SN Ib to SN Ic would systematically change as a function of metallicity, and which new types of SNe are expected in binary systems at low metallicity.

  15. The effect of Nb–B inoculation on binary hypereutectic and near-eutectic LM13 Al–Si cast alloys

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, M.; Bolzoni, L., E-mail: leandro.bolzoni@brunel.ac.uk; Hari Babu, N.

    2015-08-25

    Highlights: • Nb–B inoculation on near-eutectic and hyper-eutectic Al–Si alloys is studied. • Nb–B inoculants reduce the size of primary α-Al via heterogeneous nucleation. • Nb–B inoculation permits to obtain finer eutectic and primary Si particles. • Nb–B inoculants do not interact with common modifiers (Sr) or Si nucleants (P). - Abstract: Hyper-eutectic Al–Si alloys are used for wear-resistant components, such as pistons, because their microstructure is composed by ductile aluminium dendrites and hard primary silicon particles. In this study the effect of Nb–B inoculation on the microstructural features of binary hyper-eutectic and near-eutectic LM13 Al–Si alloys is assessed. It is found that the inoculation with Nb-based compounds (i.e. NbB{sub 2} and Al{sub 3}Nb) leads to the refinement of the microstructural features (i.e. finer and more homogeneous distribution of the eutectic phase as well as smaller primary Si particles as secondary effects). The study also demonstrates that the addition of Nb–B inoculants do not interfere with additions of strontium (used to modify the morphology of the eutectic phase) or phosphorous (added to nucleate primary Si particles)

  16. Composition-dependent electrocatalytic activity of palladium-iridium binary alloy nanoparticles supported on the multiwalled carbon nanotubes for the electro-oxidation of formic acid.

    Science.gov (United States)

    Bao, Jianming; Dou, Meiling; Liu, Haijing; Wang, Feng; Liu, Jingjun; Li, Zhilin; Ji, Jing

    2015-07-22

    Surface-functionalized multiwalled carbon nanotubes (MWCNTs) supported Pd100-xIrx binary alloy nanoparticles (Pd100-xIrx/MWCNT) with tunable Pd/Ir atomic ratios were synthesized by a thermolytic process at varied ratios of bis(acetylacetonate) palladium(II) and iridium(III) 2,4-pentanedionate precursors and then applied as the electrocatalyst for the formic acid electro-oxidation. The X-ray diffraction pattern (XRD) and transmission electron microscope (TEM) analysis showed that the Pd100-xIrx alloy nanoparticles with the average size of 6.2 nm were uniformly dispersed on the MWCNTs and exhibited a single solid solution phase with a face-centered cubic structure. The electrocatalytic properties were evaluated through the cyclic voltammetry and chronoamperometry tests, and the results indicated that both the activity and stability of Pd100-xIrx/MWCNT were strongly dependent on the Pd/Ir atomic ratios: the best electrocatalytic performance in terms of onset potential, current density, and stability against CO poisoning was obtained for the Pd79Ir21/MWCNT. Moreover, compared with pure Pd nanoparticles supported on MWCNTs (Pd/MWCNT), the Pd79Ir21/MWCNT exhibited enhanced steady-state current density and higher stability, as well as maintained excellent electrocatalytic activity in high concentrated formic acid solution, which was attributed to the bifunctional effect through alloying Pd with transition metal. PMID:26132867

  17. The effect of Nb–B inoculation on binary hypereutectic and near-eutectic LM13 Al–Si cast alloys

    International Nuclear Information System (INIS)

    Highlights: • Nb–B inoculation on near-eutectic and hyper-eutectic Al–Si alloys is studied. • Nb–B inoculants reduce the size of primary α-Al via heterogeneous nucleation. • Nb–B inoculation permits to obtain finer eutectic and primary Si particles. • Nb–B inoculants do not interact with common modifiers (Sr) or Si nucleants (P). - Abstract: Hyper-eutectic Al–Si alloys are used for wear-resistant components, such as pistons, because their microstructure is composed by ductile aluminium dendrites and hard primary silicon particles. In this study the effect of Nb–B inoculation on the microstructural features of binary hyper-eutectic and near-eutectic LM13 Al–Si alloys is assessed. It is found that the inoculation with Nb-based compounds (i.e. NbB2 and Al3Nb) leads to the refinement of the microstructural features (i.e. finer and more homogeneous distribution of the eutectic phase as well as smaller primary Si particles as secondary effects). The study also demonstrates that the addition of Nb–B inoculants do not interfere with additions of strontium (used to modify the morphology of the eutectic phase) or phosphorous (added to nucleate primary Si particles)

  18. Binary Systems with a Black Hole Component as Sources of Gravitational Waves

    CERN Document Server

    Koçak, D

    2016-01-01

    Discovery of gravitational waves by LIGO team (Abbott et al. 2016) bring a new era for observation of black hole systems. These new observations will improve our knowledge on black holes and gravitational physics. In this study, we present angular momentum loss mechanism through gravitational radiation for selected X-ray binary systems. The angular momentum loss in X-ray binary systems with a black hole companion due to gravitational radiation and mass loss time-scales are estimated for each selected system. In addition, their gravitational wave amplitudes are also estimated and their detectability with gravitational wave detectors has been discussed.

  19. Annex 4 - Task 08/13 final report, Producing the binary uranium alloys with alloying components Al, Mo, Zr, Nb, and B

    International Nuclear Information System (INIS)

    Due to reactivity of uranium in contact with the gasses O2, N2, H2, especially under higher temperatures uranium processing is always done in vacuum or inert gas. Melting, alloying and casting is done in high vacuum stoves. This report reviews the type of furnaces and includes detailed description of the electric furnace for producing uranium alloys which is available in the Institute

  20. Relationship between the density of supercritical CO2 +ethanol binary system and its critical properties

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Jingchang; (张敬畅); ZHANG; Jianjun; (张建军); CAO; Weiliang; (曹维良)

    2003-01-01

    The dependent relation between temperature and pressure of supercritical CO2 + ethanol binary system under the pressure range from 5 to 10 MPa with the variety of densities and mole fractions of ethanol that range from 0 to 2% was investigated by the static visual method in a constant volume. The critical temperature and pressure were experimentally determined simultaneously. The PTρ figures at different ethanol contents were described based on the determined pressure and temperature data, from which pressure of supercritical CO2 + ethanol binary system was found to increase linearly with the increasing temperature. P-T lines show certain convergent feature in a specific concentration of ethanol and the convergent points shift to the region of higher temperature and pressure with the increasing ethanol compositions. Furthermore, the effect of density and ethanol concentration on the critical point of CO2 + ethanol binary system was discussed in details. Critical points increase linearly with the increasing mole fraction of ethanol in specific density and critical points change at different densities. The critical compressibility factors Zc of supercritical CO2 + ethanol binary systems at different compositions of ethanol were calculated and Zc-ρ figure was obtained accordingly. It was found from Zc-ρ figure that critical compressibility factors of supercritical CO2 unitary or binary systems decline linearly with the increasing density, by which the critical point can be predicted precisely.

  1. Rotationally-Driven Fragmentation for the Formation of the Binary Protostellar System L1551 IRS 5

    CERN Document Server

    Lim, Jeremy; Hanawa, Tomoyuki; Takakuwa, Shigehisa; Matsumoto, Tomoaki; Saigo, Kazuya

    2016-01-01

    Either bulk rotation or local turbulence is widely invoked to drive fragmentation in collapsing cores so as to produce multiple star systems. Even when the two mechanisms predict different manners in which the stellar spins and orbits are aligned, subsequent internal or external interactions can drive multiple systems towards or away from alignment thus masking their formation process. Here, we demonstrate that the geometrical and dynamical relationship between the binary system and its surrounding bulk envelope provide the crucial distinction between fragmentation models. We find that the circumstellar disks of the binary protostellar system L1551 IRS 5 are closely parallel not just with each other but also with their surrounding flattened envelope. Measurements of the relative proper motion of the binary components spanning nearly 30 yr indicate an orbital motion in the same sense as the envelope rotation. Eliminating orbital solutions whereby the circumstellar disks would be tidally truncated to sizes smal...

  2. Solid—Liquid Equilibria of Several Binary and Ternary Systems Containing Meleic Anhydride

    Institute of Scientific and Technical Information of China (English)

    MAPeisheng; CHENMingming; 等

    2002-01-01

    Solid-liquid equilibria(SLE) of three binary systems and seven ternary systems containing maleic anhydride(MA) are measured by visual method. The experimental data are compared with the calculated ones with modified universal quasichemical functional group activity coefficient(UNIFAC) method in which the interaction parameters between groups come from two sources,dortmund data bank (DDB), if there′s any,and correlations based on our former presented experimental SLE data of twenty binary systems.New groups of MA,ACCOO group,COO group,>C=O group and cy-CH2 group are defined and the SLE data of maleic anhydride in isopropyl acetate in literature are cited in order to assess the new interaction parameters,correlated with Wilson equation and the λh equation.The modified UNIFAC method with these new regressed interaction parameters is also used to predict other three binary systems containing maleic anhydride.

  3. The estimation of corrosion behaviour of ZrTi binary alloys for dental applications using electrochemical techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mareci, Daniel [“Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, Iasi (Romania); Bolat, Georgiana, E-mail: georgiana20022@yahoo.com [“Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, Iasi (Romania); Chelariu, Romeu [“Gheorghe Asachi” Technical University of Iasi, Faculty of Materials Science and Engineering, Iasi (Romania); Sutiman, Daniel [“Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, Iasi (Romania); Munteanu, Corneliu [“Gheorghe Asachi” Technical University of Iasi, Faculty of Mechanical, Iasi (Romania)

    2013-08-15

    Titanium and zirconium are in the same group in the periodic table of elements and are known to have similar physical and chemical properties. Both Ti and Zr usually have their surfaces covered by a thin oxide film spontaneously formed in air. However, the cytotoxicity of ZrO{sub 2} is lower than that of TiO{sub 2} rutile. Treatments with fluoride are known as the main methods to prevent plaque formation and dental caries. The corrosion behaviour of ZrTi alloys with Ti contents of 5, 25 and 45 wt.% and cp-Ti was investigated for dental applications. All samples were tested by linear potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) performed in artificial saliva with different pH levels (5.6 and 3.4) and different fluoride (1000 ppm F{sup −}) and albumin protein (0.6%) contents. In addition, scanning electron microscopy (SEM) was employed to observe the surface morphology of the test materials after linear potentiodynamic polarisation. The corrosion current densities for the ZrTi alloys increased with the titanium content. The Zr5Ti and Zr25Ti alloys were susceptible to localised corrosion. The role that Ti plays as an alloying element is that of increasing the resistance of ZrTi alloy to localised corrosion. The presence of 0.6% albumin protein in fluoridated acidified artificial saliva with 1000 ppm F{sup −} could protect the cp-Ti and ZrTi alloys from attack by fluoride ions. - Highlights: • Electrochemical and corrosion behaviour of the new ZrTi alloys were investigated. • The passive behaviour for all the ZrTi alloys is observed. • Addition of Ti to Zr improves the corrosion resistance in some fluoridated saliva. • The presence of albumin could prevent the ZrTi alloys from attack by fluoride ions.

  4. Morphological Evolution of Disc Galaxies in Binary Systems

    CERN Document Server

    Chan, R

    2013-01-01

    We present the results of several numerical simulations of disc binary galaxies. It was performed detailed numerical N-body simulations of the dynamical interaction of two disc galaxies. The disc galaxies are embedded in spherical halos of dark matter and present central bulges. The dynamical evolution of the binary galaxy is analyzed in order to study the morphological evolution of the stellar distribution of the discs. The satellite galaxy is held on fixed, coplanar or polar discs, of eccentric ($e=0.1$, $e=0.4$ or $e=0.7$) orbits. Both galaxies have the same mass and size similar to the Milk Way. We have shown that the merge of two disc galaxy, depending on the initial conditions, can result in a disc or a lenticular galaxy, instead of an elliptical one. Besides, we have demonstrated that the time of merging increases linearly with the initial apocentric distance of the galaxies and decreases with the orbit's eccentricity. We also have shown that the tidal forces and the fusion of the discs can excite tran...

  5. Observational Investigations on Contact Binaries in Multiple-star Systems and Star Clusters

    Science.gov (United States)

    Liu, L.

    2013-01-01

    The W UMa-type contact binaries are strongly interacting systems whose components both fill their critical Roche lobes and share a convective common envelope. The models of contact binaries are bottlenecked due to too many uncertain parameters. In the 1960s and 1970s, the common convective envelope model was accepted after several fierce controversies. And then, the thermal relaxation oscillation (TRO) model, the discontinuity model, and the angular momentum loss (AML) model appeared. However, in the past forty years, there lacked remarkable advance. The coexistence of many unknown parameters blocks the theoretical development of contact binaries. A study on the contact binaries in multiple star systems and star clusters, which could provide lots of information for their formation and evolution, may be a potential growing point for understanding these objects. More and more evidence shows that many of contact binaries are located in multiple star systems and star clusters. In this thesis, we observed and analyzed contact binaries in the forementioned systems. The observational and theoretical studies for contact binary are also summarized briefly. The results obtained are as follows: (1) Three contact binaries V1128 Tau, GZ And, VW Boo which possess visual companions show periodic oscillations. The period ranges from 16.7 years to 46.5 years. These oscillations probably come from the orbital movement of a close third body. (2) Four contact binaries GSC 02393-00680, V396 Mon, FU Dra, SS Ari which do not have visual companions also present periodic oscillations. Whether they are real members of multiple star systems needs further investigations. These oscillations probably result from the orbital movement of a close M-type companion. (3) The periods of three contact binaries EQ Cep, ER Cep and V371 Cep in the old open cluster NGC 188 show a long-term increase. There is a cyclic period oscillation in ER Cep, with a period of 5.4 years. We find that the total mass of

  6. Low Temperature Shape Memory Alloys for Adaptive, Autonomous Systems Project

    Science.gov (United States)

    Falker, John; Zeitlin, Nancy; Williams, Martha; Benafan, Othmane; Fesmire, James

    2015-01-01

    The objective of this joint activity between Kennedy Space Center (KSC) and Glenn Research Center (GRC) is to develop and evaluate the applicability of 2-way SMAs in proof-of-concept, low-temperature adaptive autonomous systems. As part of this low technology readiness (TRL) activity, we will develop and train low-temperature novel, 2-way shape memory alloys (SMAs) with actuation temperatures ranging from 0 C to 150 C. These experimental alloys will also be preliminary tested to evaluate their performance parameters and transformation (actuation) temperatures in low- temperature or cryogenic adaptive proof-of-concept systems. The challenge will be in the development, design, and training of the alloys for 2-way actuation at those temperatures.

  7. Isobaric Vapor—Liquid Equilibrium for Methyldichlorosilane+Methylvinyldichlorosilane+Toluene and Constituent Binary Systems

    Institute of Scientific and Technical Information of China (English)

    邱祖民; 孙Wei; 余淑娴; 余祖兵

    2003-01-01

    Vapor-liquid euilibrium (VLE) for a ternary system of Methyldichlorosilane+methylvinyldichlorosilane+toluene and constituent binary systems were measured at 101.3kPa using a new type of magnetical pump-ebulliometer,The equilibrium conpositions of the vapor phase of binary systems were calculated indirectly from the total pressure-temperature-liquid composition(pTx).The experimental data were correlated with the Wilson and NRTL(non-random two liquid )equations.The parameters of the Wilson moldel were employed to predict the ternary VLE data .The calculated boiling points were in good agreement with the experimental ones.

  8. Study on Phase Equilibrium Properties for CO2+Cosolvent Binary Systems

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this study, the constant volume, visual method is used to measure thc critical point of CO2toluene, CO2+cyclohexane, CO2+n-butyraldehyde, CO2+i-butyraldchyde, CO2+methanol and CO2+alcohol binary systems. The relationship between critical point and the concentration of the entrainer for different substances has been discussed, and the comparison of the phase behavior of single component system and that of binary systems have been carried out.

  9. Apsidal motions of 90 eccentric binary systems in the Small Magellanic Cloud

    Science.gov (United States)

    Hong, Kyeongsoo; Lee, Jae Woo; Kim, Seung-Lee; Koo, Jae-Rim; Lee, Chung-UK

    2016-07-01

    We examined light curves of 1138 stars brighter than 18.0 mag in the I band and less than a mean magnitude error of 0.1 mag in the V band from the Optical Gravitational Lensing Experiment (OGLE)-III eclipsing binary catalogue, and found 90 new binary systems exhibiting apsidal motion. In this study, the samples of apsidal motion stars in the Small Magellanic Cloud (SMC) were increased by a factor of about 3.0 than previously known. In order to determine the period of the apsidal motion for the binaries, we analysed in detail both the light curves and eclipse timings using the MACHO (MAssive Compact Halo Objects) and OGLE photometric data base. For the eclipse timing diagrams of the systems, new times of minimum light were derived from the full light curve combined at intervals of one year from the survey data. The new 90 binaries have apsidal motion periods in the range of 12-897 yr. An additional short-term oscillation was detected in four systems (OGLE-SMC-ECL-1634, 1947, 3035, and 4946), which most likely arises from the existence of a third body orbiting each eclipsing binary. Since the systems presented here are based on homogeneous data and have been analysed in the same way, they are suitable for further statistical analysis.

  10. Apsidal motions of 90 eccentric binary systems in the Small Magellanic Cloud

    CERN Document Server

    Hong, K; Kim, S -L; Koo, J -R; Lee, C -U

    2016-01-01

    We examined light curves of 1138 stars brighter than 18.0 mag in the $I$ band and less than a mean magnitude error of 0.1 mag in the $V$ band from the OGLE-III eclipsing binary catalogue, and found 90 new binary systems exhibiting apsidal motion. In this study, the samples of apsidal motion stars in the SMC were increased by a factor of about 3 than previously known. In order to determine the period of the apsidal motion for the binaries, we analysed in detail both the light curves and eclipse timings using the MACHO and OGLE photometric database. For the eclipse timing diagrams of the systems, new times of minimum light were derived from the full light curve combined at intervals of one year from the survey data. The new 90 binaries have apsidal motion periods in the range of 12$-$897 years. An additional short-term oscillation was detected in four systems (OGLE-SMC-ECL-1634, 1947, 3035, and 4946), which most likely arises from the existence of a third body orbiting each eclipsing binary. Since the systems p...

  11. Black holes in stellar-mass binary systems: expiating original spin?

    Science.gov (United States)

    King, Andrew; Nixon, Chris

    2016-10-01

    We investigate systematically whether accreting black hole systems are likely to reach global alignment of the black hole spin and its accretion disc with the binary plane. In low-mass X-ray binaries (LMXBs), there is only a modest tendency to reach such global alignment, and it is difficult to achieve fully: except for special initial conditions, we expect misalignment of the spin and orbital planes by ˜1 rad for most of the LMXB lifetime. The same is expected in high-mass X-ray binaries. A fairly close approach to global alignment is likely in most stellar-mass ultraluminous X-ray binary systems (ULXs) where the companion star fills its Roche lobe and transfers mass on a thermal or nuclear time-scale to a black hole of lower mass. These systems are unlikely to show orbital eclipses, as their emission cones are close to the hole's spin axis. This offers a potential observational test, as models for ULXs invoking intermediate-mass black holes do predict eclipses for ensembles of ≳ 10 systems. Recent observational work shows that eclipses are either absent or extremely rare in ULXs, supporting the picture that most ULXs are stellar-mass binaries with companion stars more massive than the accretor.

  12. Millions of Multiples: Detecting and Characterizing Close-Separation Binary Systems in Synoptic Sky Surveys

    CERN Document Server

    Terziev, Emil; Arcavi, Iair; Baranec, Christoph; Bloom, Joshua S; Bui, Khanh; Burse, Mahesh P; Chorida, Pravin; Das, H K; Dekany, Richard G; Kraus, Adam L; Kulkarni, S R; Nugent, Peter; Ofek, Eran O; Punnadi, Sujit; Ramaprakash, A N; Riddle, Reed; Tendulkar, Shriharsh P

    2012-01-01

    The direct detection of binary systems in wide-field surveys is limited by the size of the stars' point-spread-functions (PSFs). A search for elongated objects can find closer companions, but is limited by the precision to which the PSF shape can be calibrated for individual stars. We have developed the BinaryFinder algorithm to search for close binaries by using precision measurements of PSF ellipticity across wide-field survey images. We show that the algorithm is capable of reliably detecting binary systems down to approximately 1/5 of the seeing limit, and can directly measure the systems' position angles, separations and contrast ratios. To verify the algorithm's performance we evaluated 100,000 objects in Palomar Transient Factory (PTF) wide-field-survey data for signs of binarity, and then used the Robo-AO robotic laser adaptive optics system to verify the parameters of 44 high-confidence targets. We show that BinaryFinder correctly predicts the presence of close companions with a <5% false-positive...

  13. Influence of the substitutional solute on the mechanical properties of Ti-Nb binary alloys for biomedical use

    Directory of Open Access Journals (Sweden)

    Luciano Monteiro da Silva

    2012-06-01

    Full Text Available Titanium alloys are widely used in the manufacture of biomedical implants because they possess an excellent combination of physical properties and outstanding biocompatibility. Today, the most widely used alloy is Ti-6Al-4V, but some studies have reported adverse effects with the long-term presence of Al and V in the body, without mentioning that the elasticity modulus value of this alloy is far superior to the bone. Thus, there is a need to develop new Ti-based alloys without Al and V that have a lower modulus, greater biocompatibility, and similar mechanical strength. In this paper, we investigated the effect of Nb as a substitutional solute on the mechanical properties of Ti-Nb alloys, prepared in an arc-melting furnace and characterized by density, X-ray diffraction, optical microscopy, hardness and elasticity modulus measurements. The X-ray and microscopy measurements show a predominance of the α phase. The microhardness values showed a tendency to increase with the concentration of niobium in the alloy. Regarding the elasticity modulus, it was observed a nonlinear behavior with respect to the concentration of niobium. This behavior is associated with the presence of the α phase.

  14. Surface Characterization and Cell Response of Binary Ti-Ag Alloys with CP Ti as Material Control

    Institute of Scientific and Technical Information of China (English)

    B.B. Zhang; K.J. Qiu; B.L. Wang; L. Li; Y.F. Zheng

    2012-01-01

    In this study, the surface passive films, dissolution behavior and biocompatibility of Ti-Ag alloys (with 5%, 10% and 20% Ag) were evaluated by X-ray diffraction (XRD) tests, electrochemical corrosion tests, X-ray photoelectron spectroscopy (XPS) tests, dissolution tests and in-vitro cytotoxicity tests. The surface films on the Ti-20Ag alloy are rich in Ti and much deficient in Ag with respect to alloy composition, as identified by XPS. Compared to CP Ti, Ti-SAg and Ti-20Ag alloys show larger impedances and lower capacitances, which can be associated with an increase of the passive layer thickness. Moreover, all Ti-Ag alloys exhibit negligible or low metal release in the test solutions. The in-vitro cytotoxicity results show Ti-Ag alloys seem to be as cytocompatible as CP Ti. From the viewpoint of surface passive film and cytotoxicity, Ti-SAg and Ti-20Ag are considered to be more suitable for dental applications.

  15. Liquid crystalline behaviour of mixtures of structurally dissimilar mesogens in binary systems

    Indian Academy of Sciences (India)

    Jayrang S Dave; Meera R Menon; Pratik R Patel

    2002-06-01

    We have studied four binary systems comprising four ester components, viz. 4-nitrophenyl-4'--alkoxybenzoates (where -alkoxy is nbutoxy, C4, -hexyloxy, C6, -octyloxy, C8 and -decyloxy, C10) and one azo component, 4--decyloxy phenylazo-4'-isoamyloxy benzene. A variety of mesomorphic properties are observed in these mixtures. The properties of these systems are discussed on the basis of phase diagrams.

  16. The Gibbs Energy Basis and Construction of Boiling Point Diagrams in Binary Systems

    Science.gov (United States)

    Smith, Norman O.

    2004-01-01

    An illustration of how excess Gibbs energies of the components in binary systems can be used to construct boiling point diagrams is given. The underlying causes of the various types of behavior of the systems in terms of intermolecular forces and the method of calculating the coexisting liquid and vapor compositions in boiling point diagrams with…

  17. The formation of the black hole in the X-ray binary system V404 Cyg

    NARCIS (Netherlands)

    J.C.A. Miller-Jones; P.G. Jonker; G. Nelemans; S. Portegies Zwart; V. Dhawan; W. Brisken; E. Gallo; M.P. Rupen

    2009-01-01

    Using new and archival radio data, we have measured the proper motion of the black hole X-ray binary V404 Cyg to be 9.2 +/- 0.3 mas yr(-1). Combined with the systemic radial velocity from the literature, we derive the full three-dimensional heliocentric space velocity of the system, which we use to

  18. Recognition of binary x-ray systems utilizing the doppler effect

    Science.gov (United States)

    Novak, B. L.

    1980-01-01

    The possibility of recognizing the duality of a single class of X-ray systems utilizing the Doppler effect is studied. The procedure is based on the presence of a period which coincides with the orbital period at the intensity of the radiation in a fixed energy interval of the X-ray component of a binary system.

  19. The VLT-FLAMES Tarantula Survey. II. R139 revealed as a massive binary system

    NARCIS (Netherlands)

    Taylor, W.D.; Evans, C.J.; Brott, I.; de Koter, A.; Vink, J.S.

    2011-01-01

    We report the discovery that R139 in 30 Doradus is a massive spectroscopic binary system.Multi-epoch optical spectroscopy of R139 was obtained as part of the VLT-FLAMES Tarantula Survey, revealing a double-lined system. The two components are of similar spectral types; the primary exhibits strong C

  20. Binary systems solubilities of inorganic and organic compounds, v.1 pt.2

    CERN Document Server

    Stephen, H

    2013-01-01

    Solubilities of Inorganic and Organic Compounds, Volume 1: Binary Systems, Part 1 is part of an approximately 5,500-page manual containing a selection from the International Chemical Literature on the Solubilities of Elements, Inorganic Compounds, Metallo-organic and Organic Compounds in Binary, Ternary and Multi-component Systems. A careful survey of the literature in all languages by a panel of scientists specially appointed for the task by the U.S.S.R. Academy of Sciences, Moscow, has made the compilation of this work possible. The complete English edition in five separately bound volumes w

  1. The evolution of naked helium stars with a neutron-star companion in close binary systems

    OpenAIRE

    Dewi, J D M; Pols, O. R; Savonije, G.J.; Heuvel, E.P.J. van den

    2002-01-01

    The evolution of helium stars with masses of 1.5 - 6.7 M_sun in binary systems with a 1.4 M_sun neutron-star companion is presented. Such systems are assumed to be the remnants of Be/X-ray binaries with B-star masses in the range of 8 - 20 M_sun which underwent a case B or case C mass transfer and survived the common-envelope and spiral-in process. The orbital period is chosen such that the helium star fills its Roche lobe before the ignition of carbon in the centre. We distinguish case BA (i...

  2. Estimation of limiting solubility of low soluble components under eutectic transformations in the binary metallic systems

    International Nuclear Information System (INIS)

    The calculation approach for estimation of limiting solubility of low soluble components under eutectic transformations in the binary metallic systems is developed. Introduced approach inserts in the next stages of research: definition of the limiting distribution coefficients of elements k0limB which have trace solubility in foundation (absence of liquidus curve in the angle of state diagram); calculation of the equilibrium distribution coefficients k0B under temperature and composition of eutectic transformation; definition of limiting concentrations of solubility in the solid phase xSBE under eutectic transformations of the binary systems A-B

  3. Automated Generation of Phase Diagrams for Binary Systems with Azeotropic Behavior

    DEFF Research Database (Denmark)

    Cismondi, Martin; Michelsen, Michael Locht; Zabaloy, Marcelo S.

    2008-01-01

    In this work, we propose a computational strategy and methods for the automated calculation of complete loci of homogeneous azeotropy of binary mixtures and the related Pxy and Txy diagrams for models of the equation-of-state (EOS) type. The strategy consists of first finding the system's azeotro......In this work, we propose a computational strategy and methods for the automated calculation of complete loci of homogeneous azeotropy of binary mixtures and the related Pxy and Txy diagrams for models of the equation-of-state (EOS) type. The strategy consists of first finding the system...

  4. Asphericity in the Fermi Surface and Fermi Energy of Na-K, Na-Rb and Na-Cs Binary Alloys

    Institute of Scientific and Technical Information of China (English)

    Minal H. Patel; A.M. Vora; P.N. Gajjar; A.R. Jani

    2002-01-01

    Detailed theoretical investigations into asphericity in the Fermi surface (FS) and Fermi energy (FE) ofNa1_xKx, Na1_xRbx, and Na1_xCsx binary solid solutions are carried out for the first time. The alloying behavior ofthe K, Rb, and Cs with the Na generates the Fermi surface distortion (FSD) of bce simple metals. The FS of Na-K,Na-Rb, and Na-Cs solid solution is a distorted sphere with the largest deviation along [110]. We have found that theimpact of local-field correction function on FSD is maximun at [100] point and minimum at [111] point. The exchangeand correlation effect is found to suppress the value of FE.

  5. Orbital Evolution of Mass-transferring Eccentric Binary Systems. I. Phase-dependent Evolution

    Science.gov (United States)

    Dosopoulou, Fani; Kalogera, Vicky

    2016-07-01

    Observations reveal that mass-transferring binary systems may have non-zero orbital eccentricities. The time evolution of the orbital semimajor axis and eccentricity of mass-transferring eccentric binary systems is an important part of binary evolution theory and has been widely studied. However, various different approaches to and assumptions on the subject have made the literature difficult to comprehend and comparisons between different orbital element time evolution equations not easy to make. Consequently, no self-consistent treatment of this phase has ever been included in binary population synthesis codes. In this paper, we present a general formalism to derive the time evolution equations of the binary orbital elements, treating mass loss and mass transfer as perturbations of the general two-body problem. We present the self-consistent form of the perturbing acceleration and phase-dependent time evolution equations for the orbital elements under different mass loss/transfer processes. First, we study the cases of isotropic and anisotropic wind mass loss. Then, we proceed with non-isotropic ejection and accretion in a conservative as well as a non-conservative manner for both point masses and extended bodies. We compare the derived equations with similar work in the literature and explain the existing discrepancies.

  6. Orbital evolution of mass-transferring eccentric binary systems. I. Phase-dependent evolution

    CERN Document Server

    Dosopoulou, Fani

    2016-01-01

    Observations reveal that a large amount of close binary systems have a finite eccentricity. The time-evolution of the orbital semi-major axis and eccentricity of mass-transferring eccentric binary systems is an important part of binary evolution theory and has been widely studied. However, various different approaches and assumptions on the subject have made the literature difficult to comprehend and comparisons between different orbital element time-evolution equations not easy to make. Consequently, no self-consistent treatment of this phase has been ever included in binary population synthesis codes. In this paper, we present a general formalism to derive the time-evolution equations of the binary orbital elements, treating mass-loss and mass-transfer as perturbations to the general two-body problem. We present the self-consistent form of the perturbing acceleration and the phase-dependent time-evolution equations for the orbital elements under different mass-loss/transfer processes. First, we study the ca...

  7. Hydrodynamic moving-mesh simulations of the common envelope phase in binary stellar systems

    CERN Document Server

    Ohlmann, Sebastian T; Pakmor, Ruediger; Springel, Volker

    2015-01-01

    The common envelope (CE) phase is an important stage in binary stellar evolution. It is needed to explain many close binary stellar systems, such as cataclysmic variables, Type Ia supernova progenitors, or X-ray binaries. To form the resulting close binary, the initial orbit has to shrink, thereby transferring energy to the primary giant's envelope that is hence ejected. The details of this interaction, however, are still not understood. Here, we present new hydrodynamic simulations of the dynamical spiral-in forming a CE system. We apply the moving-mesh code AREPO to follow the interaction of a $1M_\\odot$ compact star with a $2M_\\odot$ red giant possessing a $0.4M_\\odot$ core. The nearly Lagrangian scheme combines advantages of smoothed particle hydrodynamics and traditional grid-based hydrodynamic codes and allows us to capture also small flow features at high spatial resolution. Our simulations reproduce the initial transfer of energy and angular momentum from the binary core to the envelope by spiral shoc...

  8. A more effective coordinate system for parameter estimation of precessing compact binaries from gravitational waves

    CERN Document Server

    Farr, Benjamin; Farr, Will M; O'Shaughnessy, Richard

    2014-01-01

    Ground-based gravitational wave detectors are sensitive to a narrow range of frequencies, effectively taking a snapshot of merging compact-object binary dynamics just before merger. We demonstrate that by adopting analysis parameters that naturally characterize this 'picture', the physical parameters of the system can be extracted more efficiently from the gravitational wave data, and interpreted more easily. We assess the performance of MCMC parameter estimation in this physically intuitive coordinate system, defined by (a) a frame anchored on the binary's spins and orbital angular momentum and (b) a time at which the detectors are most sensitive to the binary's gravitational wave emission. Using anticipated noise curves for the advanced-generation LIGO and Virgo gravitational wave detectors, we find that this careful choice of reference frame and reference time significantly improves parameter estimation efficiency for BNS, NS-BH, and BBH signals.

  9. The Be/X-ray binary system V 0332+53: A Short Review

    CERN Document Server

    Caballero-Garcia, M D; Arabaci, M Ozbey; Hudec, R

    2015-01-01

    Be/X-ray binary systems provide an excellent opportunity to study the physics around neutron stars through the study of the behaviour of matter around them. Intermediate and low-luminosity type outbursts are interesting because they provide relatively clean environments around neutron stars. In these conditions the physics of the magnetosphere around the neutron star can be better studied without being very disturbed by other phenomena regarding the transfer of matter between the two components of the Be/X-ray binary system. A recent study presents the optical longterm evolution of the Be/X-ray binary V 0332+53 plus the X-ray emission mainly during the intermediate-luminosity outburst on 2008. In this paper we comment on the context of these observations and on the properties that can be derived through the analysis of them.

  10. KIC 10080943: An eccentric binary system containing two pressure and gravity mode hybrid pulsators

    CERN Document Server

    Schmid, V S; Aerts, C; Degroote, P; Bloemen, S; Murphy, S J; Van Reeth, T; Papics, P I; Bedding, T R; Keen, M A; Prsa, A; Menu, J; Debosscher, J; Hrudkova, M; De Smedt, K; Lombaert, R; Nemeth, P

    2015-01-01

    Gamma Doradus and delta Scuti pulsators cover the transition region between low mass and massive main-sequence stars, and are as such critical for testing stellar models. When they reside in binary systems, we can combine two independent methods to derive critical information, such as precise fundamental parameters to aid asteroseismic modelling. In the Kepler light curve of KIC10080943, clear signatures of gravity and pressure mode pulsations have been found. Ground-based spectroscopy revealed this target to be a double-lined binary system. We present the analysis of four years of Kepler photometry and high-resolution spectroscopy to derive observational constraints, which will serve to evaluate theoretical predictions of the stellar structure and evolution for intermediate-mass stars. We used the method of spectral disentangling to determine atmospheric parameters for both components and derive the orbital elements. With phoebe we modelled the ellipsoidal variation and reflection signal of the binary in the...

  11. Bounds for the Sum Capacity of Binary CDMA Systems in Presence of Near-Far Effect

    CERN Document Server

    Pad, P; Mansouri, S M; Kabir, P; Marvasti, F

    2010-01-01

    In this paper we are going to estimate the sum capacity of a binary CDMA system in presence of the near-far effect. We model the near-far effect as a random variable that is multiplied by the users binary data before entering the noisy channel. We will find a lower bound and a conjectured upper bound for the sum capacity in this situation. All the derivations are in the asymptotic case. Simulations show that especially the lower bound is very tight for typical values Eb/N0 and near-far effect. Also, we exploit our idea in conjunction with the Tanaka's formula [6] which also estimates the sum capacity of binary CDMA systems with perfect power control.

  12. Effect of erbium modification on the microstructure, mechanical and corrosion characteristics of binary Mg–Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Seetharaman, Sankaranarayanan, E-mail: seetharaman.s@nus.edu.sg [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, 117576 (Singapore); Blawert, Carsten [Helmholtz-Zentrum Geesthacht, Magnesium Innovation Centre, Max-Planck-Straße 1, D-21502, Geesthacht (Germany); Ng, Baoshu Milton [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, 117576 (Singapore); Wong, Wai Leong Eugene [School of Mechanical and Systems Engineering, New Castle University International Singapore, 180 Ang Mo Kio Avenue 8, 569830 (Singapore); Goh, Chwee Sim [ITE Technology Development Centre, ITE College Central, 2 Ang Mo Kio Drive, 567720 (Singapore); Hort, Norbert [Helmholtz-Zentrum Geesthacht, Magnesium Innovation Centre, Max-Planck-Straße 1, D-21502, Geesthacht (Germany); Gupta, Manoj, E-mail: mpegm@nus.edu.sg [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, 117576 (Singapore)

    2015-11-05

    In this study, new erbium modified Mg–Al alloys were developed by integrating trace erbium (in the form of Al{sub 94.67}Er{sub 5.33} master alloy) into pure Mg using disintegrated melt deposition technique. The developed Er- modified Mg–Al alloys were investigated for their microstructural, mechanical and corrosion characteristics in comparison with their unmodified counterparts. Microstructural investigation revealed (i) improved purity, (ii) (marginal) grain refinement, (iii) more uniform second phase distribution and (iv) Al{sub 3}Er phase formation due to Er modification. Mechanical property measurements revealed an overall enhancement under indentation, tension and compression loads. A remarkable improvement in tensile ductility (without adverse effects on strength) by +19%, +29%, and +58% was obtained in Mg–3Al–0.1Er, Mg–6Al–0.3Er and Mg–9Al–0.5Er when compared to Mg–3Al, Mg–6Al and Mg–9Al respectively. While the Mg–6Al–0.3Er alloy exhibited best ductility, the Mg–9Al–0.5Er has the best strength under both tension and compression loads. Corrosion characteristics evaluated by hydrogen evolution, salt spray and electrochemical impedance experiments revealed improved corrosion resistance of Er modified Mg–Al alloys by the enhanced purity levels and the formation of Al–Er phases. - Highlights: • New erbium modified Mg–Al alloys successfully synthesized using DMD method. • Erbium modification promoted Al{sub 3}Er formation and improved the purity. • Remarkable improvement in tensile ductility obtained after erbium modification. • The developed erbium modified Mg–Al alloys exhibit improved corrosion resistance.

  13. SMA OBSERVATIONS OF CLASS 0 PROTOSTARS: A HIGH ANGULAR RESOLUTION SURVEY OF PROTOSTELLAR BINARY SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xuepeng [Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008 (China); Arce, Hector G.; Dunham, Michael M. [Department of Astronomy, Yale University, Box 208101, New Haven, CT 06520-8101 (United States); Zhang Qizhou; Bourke, Tyler L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Launhardt, Ralf; Henning, Thomas [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Jorgensen, Jes K. [Niels Bohr Institute and Centre for Star and Planet Formation, Copenhagen University, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Lee, Chin-Fei [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China); Foster, Jonathan B. [Institute for Astrophysical Research, Boston University, Boston, MA 02215 (United States); Pineda, Jaime E., E-mail: xpchen@pmo.ac.cn, E-mail: xuepeng.chen@yale.edu [ESO, Karl Schwarzschild Str. 2, D-85748 Garching bei Munchen (Germany)

    2013-05-10

    We present high angular resolution 1.3 mm and 850 {mu}m dust continuum data obtained with the Submillimeter Array toward 33 Class 0 protostars in nearby clouds (distance < 500 pc), which represents so far the largest survey toward protostellar binary/multiple systems. The median angular resolution in the survey is 2.''5, while the median linear resolution is approximately 600 AU. Compact dust continuum emission is observed from all sources in the sample. Twenty-one sources in the sample show signatures of binarity/multiplicity, with separations ranging from 50 AU to 5000 AU. The numbers of singles, binaries, triples, and quadruples in the sample are 12, 14, 5, and 2, respectively. The derived multiplicity frequency (MF) and companion star fraction (CSF) for Class 0 protostars are 0.64 {+-} 0.08 and 0.91 {+-} 0.05, respectively, with no correction for completeness. The derived MF and CSF in this survey are approximately two times higher than the values found in the binary surveys toward Class I young stellar objects, and approximately three (for MF) and four (for CSF) times larger than the values found among main-sequence stars, with a similar range of separations. Furthermore, the observed fraction of high-order multiple systems to binary systems in Class 0 protostars (0.50 {+-} 0.09) is also larger than the fractions found in Class I young stellar objects (0.31 {+-} 0.07) and main-sequence stars ({<=}0.2). These results suggest that binary properties evolve as protostars evolve, as predicted by numerical simulations. The distribution of separations for Class 0 protostellar binary/multiple systems shows a general trend in which CSF increases with decreasing companion separation. We find that 67% {+-} 8% of the protobinary systems have circumstellar mass ratios below 0.5, implying that unequal-mass systems are preferred in the process of binary star formation. We suggest an empirical sequential fragmentation picture for binary star formation, based on this

  14. Sintering behavior and mechanical properties of a metal injection molded Ti–Nb binary alloy as biomaterial

    International Nuclear Information System (INIS)

    Highlights: • The sintering of the MIM Ti–Nb alloy consists of three steps. • The Nb particles act as diffusion barriers during sintering. • The TiCx only precipitate in the cooling step during sintering. • The TiCx hardly influence the sintering process of MIM Ti–Nb alloy. • The MIM Ti–Nb alloy exhibits high strength, low Young’s modulus but poor ductility. - Abstract: Sintering behavior, microstructure and mechanical properties of a Ti–16Nb alloy processed by metal injection molding (MIM) technology using elemental powders were investigated in this work by optical microscopy, X-ray diffraction (XRD), dilatometer, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). It was found that from 700 °C to 1500 °C the homogenization and densification process of MIM Ti–16Nb alloy consisted of three steps, i.e., Ti-diffusion-controlled step, Ti–Nb-diffusion step and matrix-diffusion step. Titanium carbide formation was observed in the samples sintered at 1300 °C and 1500 °C, but not in the ones sintered at 900 °C and 1100 °C. The MIM Ti–16Nb specimens sintered at 1500 °C exhibited a good combination of high tensile strength and low Young’s modulus. However, the titanium carbide particles led to poor ductility

  15. Sintering behavior and mechanical properties of a metal injection molded Ti–Nb binary alloy as biomaterial

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dapeng, E-mail: dpzhao@hotmail.com [College of Biology, Hunan University, 410082 Changsha (China); Helmholtz-Zentrum Geesthacht, Institute of Materials Research, D-21502 Geesthacht (Germany); Chang, Keke [RWTH Aachen University, Materials Chemistry, D-52056 Aachen (Germany); Ebel, Thomas [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, D-21502 Geesthacht (Germany); Nie, Hemin [College of Biology, Hunan University, 410082 Changsha (China); Willumeit, Regine; Pyczak, Florian [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, D-21502 Geesthacht (Germany)

    2015-08-15

    Highlights: • The sintering of the MIM Ti–Nb alloy consists of three steps. • The Nb particles act as diffusion barriers during sintering. • The TiC{sub x} only precipitate in the cooling step during sintering. • The TiC{sub x} hardly influence the sintering process of MIM Ti–Nb alloy. • The MIM Ti–Nb alloy exhibits high strength, low Young’s modulus but poor ductility. - Abstract: Sintering behavior, microstructure and mechanical properties of a Ti–16Nb alloy processed by metal injection molding (MIM) technology using elemental powders were investigated in this work by optical microscopy, X-ray diffraction (XRD), dilatometer, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). It was found that from 700 °C to 1500 °C the homogenization and densification process of MIM Ti–16Nb alloy consisted of three steps, i.e., Ti-diffusion-controlled step, Ti–Nb-diffusion step and matrix-diffusion step. Titanium carbide formation was observed in the samples sintered at 1300 °C and 1500 °C, but not in the ones sintered at 900 °C and 1100 °C. The MIM Ti–16Nb specimens sintered at 1500 °C exhibited a good combination of high tensile strength and low Young’s modulus. However, the titanium carbide particles led to poor ductility.

  16. An universal formula for the calculation of nitrogen solubility in liquid nitrogen-alloyed steels

    OpenAIRE

    J. Siwka; A. Hutny

    2009-01-01

    The results of the authors’ own experimental studies on the Fe - N system, its standard state, binary alloys of iron with chromium, molybdenum, manganese, nickel, vanadium, silicon and carbon, as well as ternary alloys with chromium, have made it possible to work out the whole required complex of parameters of nitrogen interaction in liquid iron alloys, including the self-interaction parameters of nitrogen-nitrogen and nitrogen-alloying elements.

  17. The Earth-Moon system as a typical binary in the Solar System

    CERN Document Server

    Ipatov, S I

    2016-01-01

    Solid embryos of the Earth and the Moon, as well as trans-Neptunian binaries, could form as a result of contraction of the rarefied condensation which was parental for a binary. The angular momentum of the condensation needed for formation of a satellite system could be mainly acquired at the collision of two rarefied condensations at which the parental condensation formed. The minimum value of the mass of the parental condensation for the Earth-Moon system could be about 0.02 of the Earth mass. Besides the main collision, which was followed by formation of the condensation that was a parent for the embryos of the Earth and the Moon, there could be another main collision of the parental condensation with another condensation. The second main collision (or a series of similar collisions) could change the tilt of the Earth. Depending on eccentricities of the planetesimals that collided with the embryos, the Moon could acquire 0.04-0.3 of its mass at the stage of accumulation of solid bodies while the mass of th...

  18. Wind-wind collision in the Carinae binary system II: Constrains to the binary orbital parameters from radio emission near periastron passage

    OpenAIRE

    Abraham, Z.; Falceta-Goncalves, D.; Dominici, T. P.; A. Caproni; Jatenco-Pereira, V.

    2005-01-01

    In this paper we use the 7 mm and 1.3 mm light curves obtained during the 2003.5 low excitation phase of the eta Carinae system to constrain the possible parameters of the binary orbit. To do that we assumed that the mm wave emission is produced in a dense disk surrounding the binary system; during the low excitation phase, which occurs close to periastron, the number of ionizing photons decreases, producing the dip in the radio emission. On the other hand, due to the large eccentricity, the ...

  19. Effect of calcium content on the microstructure, hardness and in-vitro corrosion behavior of biodegradable Mg-Ca binary alloy

    Directory of Open Access Journals (Sweden)

    Shervin Eslami Harandi

    2013-02-01

    Full Text Available Effect of calcium addition on microstructure, hardness value and corrosion behavior of five different Mg-xCa binary alloys (x = 0.7, 1, 2, 3, 4 wt. (% was investigated. Notable refinement in microstructure of the alloy occurred with increasing calcium content. In addition, more uniform distribution of Mg2Ca phase was observed in a-Mg matrix resulted in an increase in hardness value. The in-vitro corrosion examination using Kokubo simulated body fluid showed that the addition of calcium shifted the fluid pH value to a higher level similar to those found in pure commercial Mg. The high pH value amplified the formation and growth of bone-like apatite. Higher percentage of Ca resulted in needle-shaped growth of the apatite. Electrochemical measurements in the same solution revealed that increasing Ca content led to higher corrosion rates due to the formation of more cathodic Mg2Ca precipitate in the microstructure. The results therefore suggested that Mg-0.7Ca with the minimum amount of Mg2Ca is a good candidate for bio-implant applications.

  20. Effect of calcium content on the microstructure, hardness and in-vitro corrosion behavior of biodegradable Mg-Ca binary alloy

    Directory of Open Access Journals (Sweden)

    Shervin Eslami Harandi

    2012-01-01

    Full Text Available Effect of calcium addition on microstructure, hardness value and corrosion behavior of five different Mg-xCa binary alloys (x = 0.7, 1, 2, 3, 4 wt. (% was investigated. Notable refinement in microstructure of the alloy occurred with increasing calcium content. In addition, more uniform distribution of Mg2Ca phase was observed in a-Mg matrix resulted in an increase in hardness value. The in-vitro corrosion examination using Kokubo simulated body fluid showed that the addition of calcium shifted the fluid pH value to a higher level similar to those found in pure commercial Mg. The high pH value amplified the formation and growth of bone-like apatite. Higher percentage of Ca resulted in needle-shaped growth of the apatite. Electrochemical measurements in the same solution revealed that increasing Ca content led to higher corrosion rates due to the formation of more cathodic Mg2Ca precipitate in the microstructure. The results therefore suggested that Mg-0.7Ca with the minimum amount of Mg2Ca is a good candidate for bio-implant applications.

  1. Near-periodical spin period evolution in the binary system LMC X-4

    CERN Document Server

    Molkov, S; Falanga, M; Tsygankov, S; Bozzo, E

    2016-01-01

    In this paper we investigated the long-term evolution of the pulse-period in the high-mass X-ray binary LMC X-4 by taking advantage of more than 43~yrs of measurements in the X-ray domain. Our analysis revealed for the first time that the source is displaying near-periodical variations of its spin period on a time scale of roughly 6.8~yrs, making LMC X-4 one of the known binary systems showing remarkable long term spin torque reversals. We discuss different scenarios to interpret the origin of these torque reversals.

  2. Measuring the spin of black holes in binary systems using gravitational waves

    CERN Document Server

    Vitale, Salvatore; Veitch, John; Raymond, Vivien; Sturani, Riccardo

    2014-01-01

    Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions, and the opportunity of measuring spins directly through GW observations. In this letter we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientation, and signal-to-noise ratio. We find that spin magnitudes and tilt angles can be estimated to accuracy of a few percent for neutron star--black hole systems and $\\sim$ 5-30% for black hole binaries. In contrast, the difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum, and that a sudden change of behavior occurs when a system is observed from ...

  3. Density measurements under pressure for the binary system 1-propanol plus toluene

    DEFF Research Database (Denmark)

    Zeberg-Mikkelsen, Claus Kjær; Andersen, Simon Ivar

    2005-01-01

    The density of the binary system composed of 1-propanol and toluene has been measured under pressure using a vibrating-tube densimeter. The measurements have been performed for four different compositions as well as the pure compounds at four temperatures in the range of (303.15 to 333.15) K and ...

  4. High-pressure density measurements for the binary system ethanol plus heptane

    DEFF Research Database (Denmark)

    Watson, G.; Zeberg-Mikkelsen, Claus Kjær; Baylaucq, A.;

    2006-01-01

    The density of the asymmetrical binary system composed of ethanol and heptane has been measured (630 points) for nine different compositions including the pure compounds at five temperatures in the range (293.15 to 333.15) K and 14 isobars up to 65 MPa with a vibrating-tube densimeter, The experi...

  5. High-pressure viscosity measurements for the ethanol plus toluene binary system

    DEFF Research Database (Denmark)

    Zeberg-Mikkelsen, Claus Kjær; Baylaucq, A.; Watson, G.;

    2005-01-01

    The viscosity of the ethanol + toluene binary system has been measured with a falling-body viscometer for seven compositions as well as for the pure ethanol in the temperature range from 293.15 to 353.15 K and up to 100 MPa with an experimental uncertainty of 2%. At 0.1 MPa the viscosity has been...

  6. Black holes in stellar-mass binary systems: expiating original spin?

    CERN Document Server

    King, Andrew

    2016-01-01

    We investigate systematically whether accreting black hole systems are likely to reach global alignment of the black hole spin and its accretion disc with the binary plane. In low-mass X-ray binaries (LMXBs) there is only a modest tendency to reach such global alignment, and it is difficult to achieve fully: except for special initial conditions we expect misalignment of the spin and orbital planes by ~1 radian for most of the LMXB lifetime. The same is expected in high-mass X-ray binaries (HMXBs). A fairly close approach to global alignment is likely in most stellar-mass ultraluminous X-ray binary systems (ULXs) where the companion star fills its Roche lobe and transfers on a thermal timescale to a black hole of lower mass. These systems are unlikely to show orbital eclipses, as their emission cones are close to the hole's spin axis. This offers a potential observational test, as models for ULXs invoking intermediate-mass black holes do predict eclipses for ensembles of > ~10 systems. Recent observational wo...

  7. A simple estimate of gravitational wave memory in binary black hole systems

    CERN Document Server

    Garfinkle, David

    2016-01-01

    A simple estimate is given of gravitational wave memory for the inspiral and merger of a binary black hole system. Here the memory is proportional to the total energy radiated and has a simple angular dependence. This estimate might be helpful in finding better numerical relativity memory waveforms.

  8. A simple estimate of gravitational wave memory in binary black hole systems

    Science.gov (United States)

    Garfinkle, David

    2016-09-01

    A simple estimate is given of gravitational wave memory for the inspiral and merger of a binary black hole system. Here the memory is proportional to the total energy radiated and has a simple angular dependence. Estimates of this sort might be helpful as a consistency check for numerical relativity memory waveforms.

  9. Density measurements under pressure for the binary system (ethanol plus methylcyclohexane)

    DEFF Research Database (Denmark)

    Zeberg-Mikkelsen, Claus Kjær; Lugo, L.; Fernandez, J.

    2005-01-01

    The density of the asymmetrical binary system composed of ethanol and methylcyclohexane has been measured under pressure using a vibrating tube densimeter. The measurements have been performed for eight different compositions as well as the pure compounds at eight temperatures in the range 283.15...

  10. Alkali metal and ammonium chlorides in water and heavy water (binary systems)

    CERN Document Server

    Cohen-Adad, R

    1991-01-01

    This volume surveys the data available in the literature for solid-fluid solubility equilibria plus selected solid-liquid-vapour equilibria, for binary systems containing alkali and ammonium chlorides in water or heavy water. Solubilities covered are lithium chloride, sodium chloride, potassium chloride, rubidium chloride, caesium chloride and ammonium chloride in water and heavy water.

  11. A massive binary black-hole system in OJ 287 and a test of general relativity.

    Science.gov (United States)

    Valtonen, M J; Lehto, H J; Nilsson, K; Heidt, J; Takalo, L O; Sillanpää, A; Villforth, C; Kidger, M; Poyner, G; Pursimo, T; Zola, S; Wu, J-H; Zhou, X; Sadakane, K; Drozdz, M; Koziel, D; Marchev, D; Ogloza, W; Porowski, C; Siwak, M; Stachowski, G; Winiarski, M; Hentunen, V-P; Nissinen, M; Liakos, A; Dogru, S

    2008-04-17

    Tests of Einstein's general theory of relativity have mostly been carried out in weak gravitational fields where the space-time curvature effects are first-order deviations from Newton's theory. Binary pulsars provide a means of probing the strong gravitational field around a neutron star, but strong-field effects may be best tested in systems containing black holes. Here we report such a test in a close binary system of two candidate black holes in the quasar OJ 287. This quasar shows quasi-periodic optical outbursts at 12-year intervals, with two outburst peaks per interval. The latest outburst occurred in September 2007, within a day of the time predicted by the binary black-hole model and general relativity. The observations confirm the binary nature of the system and also provide evidence for the loss of orbital energy in agreement (within 10 per cent) with the emission of gravitational waves from the system. In the absence of gravitational wave emission the outburst would have happened 20 days later. PMID:18421348

  12. Properties of Dispersion Casting of Y2O3 Particles in Hypo, Hyper and Eutectic Binary Al-Cu Alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In the present work, the dispersion casting of Y2O3 particles in aluminum-copper alloy was investigated in terms of microstructural changes with respect to Cu contents of 20 (hypo), 33 (eutectic) and 40 (hyper)wt pct by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). For the fabrication of Al-Cu alloy dispersed Y2O3 ceramic particles, stir casting method was employed. In case of Al-20 wt pct Cu alloy (hypoeutectic), SEM images revealed that primary Al was grown up in the beginning. After that, eutectic phase with well dispersed ceramic particles was formed. In case of eutectic composition, Y2O3 particles were uniformly dispersed in the matrix. When the Cu is added into Al up to 40 wt pct (hypereutectic), primary θ phase was grown up without any Y2O3 ceramic particles in the early stage of solidification. Thereafter,eutectic phase was formed with well dispersed ceramic particles. It can be concluded that Y2O3 ceramic particles is mostly dispersed in case of eutectic composition in Al-Cu alloy.

  13. Phase equilibria calculation of LaI3-MI (M=Na, K, Cs) binary systems

    Institute of Scientific and Technical Information of China (English)

    WANG Yu; SHAO Guoquan; LI Shaobo; SUN Yimin; QIAO Zhiyu

    2009-01-01

    The Gibbs energies of liquid phases in the LaI3-MI (M=Na, K, Cs) systems were described by the modified quasi-chemical model. From the measured phase equilibrium data of these binary systems, a set of thermodynamic functions were optimized by using the CAL-PHAD technique. The enthalpy of mixing and the interaction parameter of the liquid phase were predicted from known data for the LaI3-MI systems.

  14. The impact of viscosity on the morphology of gaseous flows in semidetached binary systems

    CERN Document Server

    Bisikalo, D V; Kuznetsov, O A; Chechetkin, V M

    2000-01-01

    Results of 3D gas dynamical simulation of mass transfer in binaries are presented for systems with various values of viscosity. Analysis of obtained solutions shows that in the systems with low value of viscosity the flow structure is qualitatively similar to one for systems with high viscosity. Presented calculations confirm that there is no shock interaction between the stream from L1 and the forming accretion disk (`hot spot') at any value of viscosity.

  15. Experimental analyses of dynamical systems involving shape memory alloys

    DEFF Research Database (Denmark)

    Enemark, Søren; Savi, Marcelo A.; Santos, Ilmar F.

    2015-01-01

    The use of shape memory alloys (SMAs) in dynamical systems has an increasing importance in engineering especially due to their capacity to provide vibration reductions. In this regard, experimental tests are essential in order to show all potentialities of this kind of systems. In this work, SMA...... springs are incorporated in a dynamical system that consists of a one degree of freedom oscillator connected to a linear spring and a mass, which is also connected to the SMA spring. Two types of springs are investigated defming two distinct systems: a pseudoelastic and a shape memory system...

  16. A Solar-type Stellar Companion to a Deep Contact Binary in a Quadruple System

    Science.gov (United States)

    Zhou, X.; Qian, S.-B.; Zhang, J.; Jiang, L.-Q.; Zhang, B.; Kreiner, J.

    2016-02-01

    The four-color (B, V, Rc, Ic) light curves of V776 Cas are presented and analyzed using the Wilson-Devinney method. It is discovered that V776 Cas is an early F-type (F2V) overcontact binary with a very high contact degree (f = 64.6%) and an extremely low-mass ratio (q = 0.130), which indicate that it is at the final evolutionary stage of cool short-period binaries. The mass of the primary and secondary stars are calculated to be M1 = 1.55(±0.04) M⊙, M2 = 0.20(±0.01) M⊙. V776 Cas is supposed to be formed from an initially detached binary system via the loss of angular momentum due to the magnetic wind. The initial masses of the present primary and secondary components are calculated to be M1i = 0.86(±0.10) M⊙ and M2i = 2.13(±0.04) M⊙. The observed-calculated curve exhibits a cyclic period variation, which is due to the light-travel time effect caused by the presence of a third component with a period of 23.7 years. The mass of the third component is estimated to be M3 = 1.04(±0.03) M⊙ and the orbital inclination of the third component is calculated to be i‧ = 33.°1. The distance of the binary system to the mass center of the triple system is calculated to be {a}12\\prime = 3.45 AU. The presence of the close-in tertiary component may play an important role in the formation and evolution of this binary system by drawing angular momentum from the central system.

  17. Gamma-rays from nebulae around binary systems containing energetic rotation powered pulsars

    CERN Document Server

    Bednarek, W

    2013-01-01

    We consider nebulae which are created around binary systems containing rotation powered pulsars and companion stars with strong stellar winds. It is proposed that the stellar and pulsar winds have to mix at some distance from the binary system, defined by the orbital period of the companion stars and the velocity of the stellar wind. The mixed pulsar-stellar wind expands with a specific velocity determined by the pulsar power and the mass loss rate of the companion star. Relativistic particles, either from the inner pulsar magnetosphere and/or accelerated at the shocks between stellar and pulsar winds, are expected to be captured and isotropized in the reference frame of the mixed wind. Therefore, they can efficiently comptonize stellar radiation producing GeV-TeV $\\gamma$-rays in the inverse Compton process. We calculate the $\\gamma$-ray spectra expected in such scenario for the two example binary systems: J1816+4510 which is the redback type millisecond binary and LS 5039 which is supposed to contain energe...

  18. Towards a Fundamental Understanding of Short Period Eclipsing Binary Systems Using Kepler Data

    Science.gov (United States)

    Prsa, Andrej

    Kepler's ultra-high precision photometry is revolutionizing stellar astrophysics. We are seeing intrinsic phenomena on an unprecedented scale, and interpreting them is both a challenge and an exciting privilege. Eclipsing binary stars are of particular significance for stellar astrophysics because precise modeling leads to fundamental parameters of the orbiting components: masses, radii, temperatures and luminosities to better than 1-2%. On top of that, eclipsing binaries are ideal physical laboratories for studying other physical phenomena, such as asteroseismic properties, chromospheric activity, proximity effects, mass transfer in close binaries, etc. Because of the eclipses, the basic geometry is well constrained, but a follow-up spectroscopy is required to get the dynamical masses and the absolute scale of the system. A conjunction of Kepler photometry and ground- based spectroscopy is a treasure trove for eclipsing binary star astrophysics. This proposal focuses on a carefully selected set of 100 short period eclipsing binary stars. The fundamental goal of the project is to study the intrinsic astrophysical effects typical of short period binaries in great detail, utilizing Kepler photometry and follow-up spectroscopy to devise a robust and consistent set of modeling results. The complementing spectroscopy is being secured from 3 approved and fully funded programs: the NOAO 4-m echelle spectroscopy at Kitt Peak (30 nights; PI Prsa), the 10- m Hobby-Eberly Telescope high-resolution spectroscopy (PI Mahadevan), and the 2.5-m Sloan Digital Sky Survey III spectroscopy (PI Mahadevan). The targets are prioritized by the projected scientific yield. Short period detached binaries host low-mass (K- and M- type) components for which the mass-radius relationship is sparsely populated and still poorly understood, as the radii appear up to 20% larger than predicted by the population models. We demonstrate the spectroscopic detection viability in the secondary

  19. Design of a Content Addressable Memory-based Parallel Processor implementing (−1+j-based Binary Number System

    Directory of Open Access Journals (Sweden)

    Tariq Jamil

    2014-11-01

    Full Text Available Contrary to the traditional base 2 binary number system, used in today’s computers, in which a complex number is represented by two separate binary entities, one for the real part and one for the imaginary part, Complex Binary Number System (CBNS, a binary number system with base (−1+j, is used to represent a given complex number in single binary string format. In this paper, CBNS is reviewed and arithmetic algorithms for this number system are presented. The design of a CBNS-based parallel processor utilizing content-addressable memory for implementation of associative dataflow concept has been described and software-related issues have also been explained.

  20. Adsorption of Geosmin and MIB on Activated Carbon Fibers-Single and Binary Solute System

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, Rangesh; Sorial, George A., E-mail: george.sorial@uc.ed [University of Cincinnati, Department of Civil and Environmental Engineering (United States)

    2009-08-15

    The adsorption of two taste- and odor-causing compounds, namely MIB (2-methyl isoborneol-C{sub 11}H{sub 20}O) and geosmin (C{sub 12}H{sub 22}O) on activated carbon was investigated in this study. The impact of adsorbent pore size distribution on adsorption of MIB and geosmin was evaluated through single solute and multicomponent adsorption of these compounds on three types of activated carbon fibers (ACFs) and one granular activated carbon (GAC). The ACFs (ACC-15, ACC-20, and ACC-25) with different degrees of activation had narrow pore size distributions and specific critical pore diameters whereas the GAC (F-400) had a wider pore size distribution and lesser microporosity. The effect of the presence of natural organic matter (NOM) on MIB and geosmin adsorption was also studied for both the single solute and binary systems. The Myers equation was used to evaluate the single solute isotherms as it converges to Henry's law at low coverage and also serves as an input for predicting multicomponent adsorption. The single solute adsorption isotherms fit the Myers equation well and pore size distribution significantly influenced adsorption on the ACFs and GAC. The ideal adsorbed solute theory (IAST), which is a well-established thermodynamic model for multicomponent adsorption, was used to predict the binary adsorption of MIB and geosmin. The IAST predicted well the binary adsorption on the ACFs and GAC. Binary adsorption isotherms were also conducted in the presence of oxygen (oxic) and absence of oxygen (anoxic). There were no significant differences in the binary isotherm between the oxic and anoxic conditions, indicating that adsorption was purely through physical adsorption and no oligomerization was taking place. Binary adsorptions for the four adsorbents were also conducted in the presence of humic acid to determine the effect of NOM and to compare with IAST predictions. The presence of NOM interestingly resulted in deviation from IAST behavior in case of two

  1. Applicability of four parameter formalisms in interpreting thermodynamic properties of binary systems

    Indian Academy of Sciences (India)

    S Acharya; J P Hajra

    2011-04-01

    The four parameter functions are generally considered to be adequate for representation of the thermodynamic properties for the strongly interacting binary systems. The present study involves a critical comparison in terms of applicability of the three well known four-parameter formalisms for the representation of the thermodynamic properties of binary systems. The study indicates that the derived values of the infinite dilution parameters based on the formalisms compare favourably with the computed data available in the literature. The standard deviations in terms of the partial and integral excess functions of all the models lie well within the experimental scatter of the computed data and coincide exactly with each other. The formalisms are useful in representation of the thermodynamic properties of most of the binary systems except for the Mg–Bi and Mg–In systems. In such systems, it appears that the additional compositional terms may be necessary for the formalisms for adequate description of behaviour of the systems. Since the derived values of the thermodynamic properties of all the formalisms match favourably over the entire compositional range for the systems as studied in the present research, any one of them may be used for adequate representation of the properties of the systems.

  2. Testing Asteroseismology with red giants in eclipsing binary and multiple-star systems

    CERN Document Server

    Gaulme, Patrick

    2013-01-01

    Red-giant stars are proving to be an incredible source of information for testing models of stellar evolution, as asteroseismology has opened up a window into their interiors. Such insights are a direct result of the unprecedented data from space missions CoRoT and Kepler as well as recent theoretical advances. Eclipsing binaries are also fundamental astrophysical objects, and when coupled with asteroseismology, they would provide two independent methods to obtain masses and radii and exciting opportunities to develop highly constrained stellar models. Gaulme et al. (2013) reported the discovery of 13 bona fide candidates (12 previously unknown) to be eclipsing binaries, one to be an non-eclipsing binary with tidally induced oscillations, and 10 more to be hierarchical triple systems, all of which include a pulsating red giant. When ground-based support in terms of atmospheric abundance and radial velocities are completed, these red giants in eclipsing binary systems have the potential to become some of the m...

  3. Estimation of vapor composition and vapor pressure of alcohols and hydrocarbons binary systems

    International Nuclear Information System (INIS)

    The objective of this study were to apply the coordination state theory to assosiated systems, especially to estimate vapor pressure and vapor composition of alcohols and hydrcarbons binary systems. To achieve these objectives, a computer programme in Q. basic language was used to compute vapor composition and vapor pressure of may alcohols and hydrcarbons binary systems. The systems studied were methane- methanol, methane- n-propanol, n-pentane - n-propanol, ethanol- cyclohexane, ethanol- isooctane, n-pentane - ethanol, methanol - benzene, n-propanol- benzene, ethane- ethanol and ethane- n-propanol. The calculated VLE values were compared with experimental data using standard deviation. The values calculated agree, in general, with the experimental ones. Variations were observed among certain cases where phase seperation may occur.(Author)

  4. The effects of low doses of 14 MeV neutrons on the tensile properties of three binary copper alloys

    International Nuclear Information System (INIS)

    Miniature tensile specimens of high purity copper and copper alloyed respectively with five atom percent of Al, Mn, and Ni were irradiated with D-T fusion neutrons in the RTNS-II to fluences up to 1.3x1022 n/m2 at 363 K. To compare fission and fusion neutron effects, some specimens were also irradiated at the same temperature to similar damage levels in the Omega West Reactor (OWR). Tensile tests were performed at room temperature, and the radiation-induced changes in tensile properties are compared as functions of displacements per atom (dpa). The irradiation-induced strengthening of Cu-5% Mn is greater than that of Cu-5% Al and Cu-5% Ni, which behave about the same. However, all the alloys sustain less irradiation-induced strengthening by 14 MeV neutrons than pure copper. The effects of fission and fusion neutrons on the yield stress of the copper alloys correlate well on the basis of dpa, in contrast to the behavior of pure copper. (orig.)

  5. Ray trajectories, binomial of a new type, and the binary system

    CERN Document Server

    Yurkin, Alexander V

    2013-01-01

    The paper describes a new algorithm of construction of the nonlinear arithmetic triangle on the basis of numerical simulation and the binary system. It demonstrates that the numbers that fill the nonlinear arithmetic triangle may be binomial coefficients of a new type. An analogy has been drawn with the binomial coefficients calculated with the use of the Pascal triangle. The paper provides a geometrical interpretation of binomials of different types in considering the branching systems of rays.

  6. Experimental study and thermodynamic assessment of the erbium-hydrogen binary system

    International Nuclear Information System (INIS)

    The erbium-hydrogen (Er-H) binary system has been investigated experimentally.New solubility limits and extensions of the homogeneity domains have been measured, using several experimental techniques,and high purity materials. A thermodynamic assessment of the system using the Calphad method has been performed.The calculated phase diagram shows a fair agreement with the experimental data. Both experimental and calculated phase diagrams obtained differ significantly from the one available in the literature. (authors)

  7. Digital system detects binary code patterns containing errors

    Science.gov (United States)

    Muller, R. M.; Tharpe, H. M., Jr.

    1966-01-01

    System of square loop magnetic cores associated with code input registers to react to input code patterns by reference to a group of control cores in such a manner that errors are canceled and patterns containing errors are accepted for amplification and processing. This technique improves reception capabilities in PCM telemetry systems.

  8. Binary Laser Direct Writing System and Its Applications

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new laser direct writing system is introduced and the potential application of the diffractive optical elements (DOE's) fabricated by applying laser direct writing system are presented. The fabrication techniques by applying the laser direct writing are developed. Experimental results have been obtained by applying laser direct writing machine with line width of 5μm and 10μm.

  9. Reconfiguration of distribution system using a binary programming model

    Directory of Open Access Journals (Sweden)

    Md Mashud Hyder

    2016-03-01

    Full Text Available Distribution system reconfiguration aims to choose a switching combination of branches of the system that optimize certain performance criteria of power supply while maintaining some specified constraints. The ability to automatically reconfigure the network quickly and reliably is a key requirement of self-healing networks which is an important part of the future Smart Grid system. We present a unified mathematical framework, which allows us to consider different objectives of distribution system reconfiguration problems in a flexible manner, and investigate its performance. The resulting optimization problem is in quadratic form which can be solved efficiently by using a quadratic mixed integer programming (QMIP solver. The proposed method has been applied for reconfiguring different standard test distribution systems.

  10. An Extremely Fast Halo Hot Subdwarf Star in a Wide Binary System

    Science.gov (United States)

    Németh, Péter; Ziegerer, Eva; Irrgang, Andreas; Geier, Stephan; Fürst, Felix; Kupfer, Thomas; Heber, Ulrich

    2016-04-01

    New spectroscopic observations of the halo hyper-velocity star candidate SDSS J121150.27+143716.2 (V = 17.92 mag) revealed a cool companion to the hot subdwarf primary. The components have a very similar radial velocity and their absolute luminosities are consistent with the same distance, confirming the physical nature of the binary, which is the first double-lined hyper-velocity candidate. Our spectral decomposition of the Keck/ESI spectrum provided an sdB+K3V pair, analogous to many long-period subdwarf binaries observed in the Galactic disk. We found the subdwarf atmospheric parameters: {T}{{eff}}=30\\600+/- 500 K, {log}g=5.57+/- 0.06 cm s‑2, and He abundance {log}(n{{He}}/n{{H}})=-3.0+/- 0.2. Oxygen is the most abundant metal in the hot subdwarf atmosphere, and Mg and Na lines are the most prominent spectral features of the cool companion, consistent with a metallicity of [{{Fe}}/{{H}}]=-1.3. The non-detection of radial velocity variations suggest the orbital period to be a few hundred days, in agreement with similar binaries observed in the disk. Using the SDSS-III flux calibrated spectrum we measured the distance to the system d=5.5+/- 0.5 {{kpc}}, which is consistent with ultraviolet, optical, and infrared photometric constraints derived from binary spectral energy distributions. Our kinematic study shows that the Galactic rest-frame velocity of the system is so high that an unbound orbit cannot be ruled out. On the other hand, a bound orbit requires a massive dark matter halo. We conclude that the binary either formed in the halo or was accreted from the tidal debris of a dwarf galaxy by the Milky Way.

  11. High-energy radiation from the massive binary system Eta Carinae

    Science.gov (United States)

    Bednarek, W.; Pabich, J.

    2011-06-01

    Context. The most massive binary system Eta Carinae has been recently established as a gamma-ray source by the AGILE and Fermi-LAT detectors. The high energy spectrum of this gamma-ray source is very intriguing. It shows two clear components and a lack of any evidence of variability with the orbital period of the binary system. Aims: We consider different scenarios for the acceleration of particles (both electrons and hadrons) and the production of the high energy radiation in the model of stellar wind collisions within the binary system Eta Carinae with the aim to explain the gamma-ray observations and predict the behaviour of the source at very high gamma-ray energies. Methods: The gamma-ray spectra calculated in terms of the specific models are compared with the observations of Eta Carinae, and the neutrino spectra produced in hadronic models are confronted with the atmospheric neutrino background and the sensitivity of 1 km2 neutrino telescope. Results: We show that spectral features can be explained in terms of the stellar wind collision model between the winds of the companion stars in which the acceleration of particles occurs on both sides of the double shock structure. The shocks from the Eta Carinae star and the companion star can accelerate particles to different energies depending on the different conditions determined by the parameters of the stars. The lack of strong GeV gamma-ray variability with the period of the binary system can be also understood in terms of such a model. Conclusions: We predict that the gamma-ray emission features at energies above ~100 GeV will show significant variability (or its lack) depending on the acceleration and interaction scenario of particles accelerated within the binary system. For the hadronic models we predict the expected range of neutrino fluxes from the binary system Eta Carinae. This can be tested through observations with the large-scale neutrino telescopes, which will support or disprove the specific

  12. Discovery of Triple Star Systems through Dynamical Eclipse Timing Variations with Kepler Eclipsing Binaries

    Science.gov (United States)

    Conroy, Kyle E.

    2016-05-01

    We present a catalog of precise eclipse times and analysis of third-body signals among 1279 close binaries in the latest Kepler Eclipsing Binary Catalog. For these short-period binaries, Kepler's 30 minute exposure time causes significant smearing of light curves. In addition, common astrophysical phenomena such as chromospheric activity, as well as imperfections in the light curve detrending process, can create systematic artifacts that may produce fictitious signals in the eclipse timings. We present a method to measure precise eclipse times in the presence of distorted light curves, such as in contact and near-contact binaries which exhibit continuously changing light levels in and out of eclipse. We identify 236 systems for which we find a timing variation signal compatible with the presence of a third body. These are modeled for the light travel time effect and the basic properties of the third body are derived. We summarize the overall distribution of mutual orbital inclination angles, which together now provide strong confirmation of the basic predictions of dynamical evolution through Kozai Cycles and Tidal Friction.

  13. Gravitational radiation by point particle eccentric binary systems in the linearised characteristic formulation of general relativity

    CERN Document Server

    M., C E Cedeño

    2016-01-01

    We study a binary system composed of point particles of unequal masses in eccentric orbits in the linear regime of the characteristic formulation of general relativity, generalising a previous study found in the literature in which a system of equal masses in circular orbits is considered. We also show that the boundary conditions on the time-like world tubes generated by the orbits of the particles can be extended beyond circular orbits. Concerning the power lost by the emission of gravitational waves, it is directly obtained from the Bondi's News function. It is worth stressing that our results are completely consistent, because we obtain the same result for the power derived by Peters and Mathews, in a different approach, in their seminal paper of 1963. In addition, the present study constitutes a powerful tool to construct extraction schemes in the characteristic formalism to obtain the gravitational radiation produced by binary systems during the inspiralling phase.

  14. On the Possibility of Habitable Trojan Planets in Binary Star Systems.

    Science.gov (United States)

    Schwarz, Richard; Funk, Barbara; Bazsó, Ákos

    2015-12-01

    Approximately 60% of all stars in the solar neighbourhood (up to 80% in our Milky Way) are members of binary or multiple star systems. This fact led to the speculations that many more planets may exist in binary systems than are currently known. To estimate the habitability of exoplanetary systems, we have to define the so-called habitable zone (HZ). The HZ is defined as a region around a star where a planet would receive enough radiation to maintain liquid water on its surface and to be able to build a stable atmosphere. We search for new dynamical configurations-where planets may stay in stable orbits-to increase the probability to find a planet like the Earth. PMID:26113154

  15. Eclipsing time variations in close binary systems: Planetary hypothesis vs. Applegate mechanism

    CERN Document Server

    Völschow, M; Perdelwitz, V; Banerjee, R

    2015-01-01

    The observed eclipsing time variations in post-common-envelope binaries (PCEBs) can be interpreted as potential evidence for massive Jupiter-like planets, or as a result of magnetic activity, leading to quasi-periodic changes in the quadrupole moment of the secondary star. The latter is commonly referred to as the Applegate mechanism. Following Brinkworth et al. (2006), we employ here an improved version of Applegate's model including the angular momentum exchange between a finite shell and the core of the star. The framework is employed to derive the general conditions under which the Applegate mechanism can work, and is subsequently applied to a sample of 16 close binary systems with potential planets, including 11 PCEBs. Further, we present a detailed derivation and study of analytical models which allow for an straightforward extension to other systems. Using our full numerical framework, we show that the Applegate mechanism can clearly explain the observed eclipsing time variations in 4 of the systems, w...

  16. On the Possibility of Habitable Trojan Planets in Binary Star Systems.

    Science.gov (United States)

    Schwarz, Richard; Funk, Barbara; Bazsó, Ákos

    2015-12-01

    Approximately 60% of all stars in the solar neighbourhood (up to 80% in our Milky Way) are members of binary or multiple star systems. This fact led to the speculations that many more planets may exist in binary systems than are currently known. To estimate the habitability of exoplanetary systems, we have to define the so-called habitable zone (HZ). The HZ is defined as a region around a star where a planet would receive enough radiation to maintain liquid water on its surface and to be able to build a stable atmosphere. We search for new dynamical configurations-where planets may stay in stable orbits-to increase the probability to find a planet like the Earth.

  17. On angular momentum transfer in binary systems. [stellar orbital period change

    Science.gov (United States)

    Wilson, R. E.; Stothers, R.

    1975-01-01

    The maximum limit for the conversion of orbital angular momentum into rotational angular momentum of the mass-gaining component in a close binary system is derived. It is shown that this conversion process does not seriously affect the rate of orbital period change and can be neglected in computing the mass transfer rate. Integration of this limit over the entire accretion process results in a value for the maximum accumulated rotational angular momentum that is 3 to 4 times larger than that implied by the observed underluminosity of stars in such systems as Mu(1) Sco, V Pup, SX Aur, and V356 Sgr. It is suggested that shell stars and emission-line stars in binary systems may be produced when the core angular momentum is transferred into an envelope having a rotational angular momentum close to the maximum limit.-

  18. Critical evaluation and thermodynamic optimization of the U-Pb and U-Sb binary systems

    Science.gov (United States)

    Wang, Jian; Jin, Liling; Chen, Chuchu; Rao, Weifeng; Wang, Cuiping; Liu, Xingjun

    2016-11-01

    A complete literature review, critical evaluation and thermodynamic optimization of the phase diagrams and thermodynamic properties of U-Pb and U-Sb binary systems are presented. The CALculation of PHAse Diagrams (CALPHAD) method was used for the thermodynamic optimization, the results of which can reproduce all available reliable experimental phase equilibria and thermodynamic data. The modified quasi-chemical model in the pair approximation (MQMPA) was used for modeling the liquid solution. The Gibbs energies of all terminal solid solutions and intermetallic compounds were described by the compound energy formalism (CEF) model. All reliable experimental data of the U-Pb and U-Sb systems have been reproduced. A self-consistent thermodynamic database has been constructed for these binary systems; this database can be used in liquid-metal fuel reactor (LMFR) research.

  19. Smearing of mass accretion rate variation by viscous processes in accretion disks in compact binary systems

    Science.gov (United States)

    Ghosh, A.; Chakrabarti, Sandip K.

    2016-09-01

    Variation of mass supply rate from the companion can be smeared out by viscous processes inside an accretion disk. Hence, by the time the flow reaches the inner edge, the variation in X-rays need not reflect the true variation of the mass supply rate at the outer edge. However, if the viscosity fluctuates around a mean value, one would expect the viscous time scale t_{{visc}} also to spread around a mean value. In high mass X-ray binaries, which are thought to be primarily wind-fed, the size of the viscous Keplerian disk is smaller and thus such a spread could be lower as compared to the low mass X-ray binaries which are primarily fed by Roche lobe overflow. If there is an increasing or decreasing trend in viscosity, the interval between enhanced emission would be modified systematically. In the absence of a detailed knowledge about the variation of mass supply rates at the outer edge, we study ideal circumstances where modulation must take place exactly in orbital time scales, such as when there is an ellipticity in the orbit. We study a few compact binaries using long term All Sky monitor (ASM) data (1.5-12 keV) of Rossi X-ray Timing Explorer (RXTE) and all sky survey data (15-50 keV) of Swift satellites by different methods to look for such smearing effects and to infer what these results can tell us about the viscous processes inside the respective disks. We employ three different methods to seek imprints of periodicity on the X-ray variation and found that in all the cases, the location of the peak in the power density spectra is consistent with the orbital frequencies. Interestingly, in high mass X-ray binaries the peaks are sharp with high rms values, consistent with a small Keplerian disk in a wind fed system. However, in low mass X-ray binaries with larger Keplerian disk component, the peaks are spreaded out with much lower rms values. X-ray reflections, or superhump phenomena which may also cause such X-ray modulations would not be affected by the size of

  20. Eccentricity evolution in hierarchical triple systems with eccentric outer binaries

    OpenAIRE

    Georgakarakos, Nikolaos

    2014-01-01

    We develop a technique for estimating the inner eccentricity in hierarchical triple systems, with the inner orbit being initially circular, while the outer one is eccentric. We consider coplanar systems with well separated components and comparable masses. The derivation of short period terms is based on an expansion of the rate of change of the Runge-Lenz vector. Then, the short period terms are combined with secular terms, obtained by means of canonical perturbation theory. The validity of ...

  1. Preparation and Evaluation of Cyclodextrin Based Binary Systems for Taste Masking

    Directory of Open Access Journals (Sweden)

    S. T. Birhade

    2010-07-01

    Full Text Available The present study was aimed to investigate the potential of cyclodextrin complexation as an approach for taste masking. For this purpose, Rizatriptan benzoate (RZBT was selected as model drug which is having bitter taste. Taste improvement of drug by β-Cyclodextrin was done by simple complexation approach using physical and kneading mixture methods with various ratios. Taste perception study was carried out in-vitro by spectrophotometrically and in-vivo by gustatory sensation to evaluate the taste masking ability of binary complexation. The optimized taste masking ratio 1:10 of kneading mixture was selected based on bitterness score and characterized by fourier transform infrared spectroscopy (FTIR, differential scanning calorimetry (DSC and X-ray diffractometry (XRD to identify the physicochemical interaction between drug and carrier and its effect on dissolution. In-vitro drug release studies for physical mixture and kneaded system were performed in pH 1.2 and 6.8 buffers. The FTIR, DSC and XRD studies indicated inclusion complexation in physical mixture and kneaded system. Both the binary systems showed effective taste masking and at the same time showed no limiting effect on the drug release. Whereas in comparison; kneading system showed better results. The results conclusively demonstrated effective taste masking by β-Cyclodextrin in both binary systems, which can be utilized as a novel alternative approach for effective taste masking.

  2. General approach to the testing of binary solubility systems for thermodynamic consistency. Consolidated Fuel Reprocessing Program

    International Nuclear Information System (INIS)

    A comparison of implicit Runge-Kutta and orthogonal collocation methods is made for the numerical solution to the ordinary differential equation which describes the high-pressure vapor-liquid equilibria of a binary system. The systems of interest are limited to binary solubility systems where one of the components is supercritical and exists as a noncondensable gas in the pure state. Of the two methods - implicit Runge-Kuta and orthogonal collocation - this paper attempts to present some preliminary but not necessarily conclusive results that the implicit Runge-Kutta method is superior for the solution to the ordinary differential equation utilized in the thermodynamic consistency testing of binary solubility systems. Due to the extreme nonlinearity of thermodynamic properties in the region near the critical locus, an extended cubic spline fitting technique is devised for correlating the P-x data. The least-squares criterion is employed in smoothing the experimental data. Even though the derivation is presented specifically for the correlation of P-x data, the technique could easily be applied to any thermodynamic data by changing the endpoint requirements. The volumetric behavior of the systems must be given or predicted in order to perform thermodynamic consistency tests. A general procedure is developed for predicting the volumetric behavior required and some indication as to the expected limit of accuracy is given

  3. Shape memory alloys applied to improve rotor-bearing system dynamics - an experimental investigation

    OpenAIRE

    Enemark, Søren; Santos, Ilmar; Marcelo A. Savi

    2015-01-01

    tor-bearing systems have critical speeds and to pass through them is an ongoing challenge in the field of mechanical engineering. The incorporation of shape memory alloys in rotating systems has an increasing importance to improve system performance and to avoid potential damaging situations when passing through critical speeds. In this work, the feasibility of applying shape memory alloys to a rotating system is experimentally investigated. Shape memory alloys can change their stiffness with...

  4. Interspecies stress in momentum equations for dense binary particulate systems.

    Science.gov (United States)

    Zhang, D Z; Ma, X; Rauenzahn, R M

    2006-07-28

    For two-species particulate systems, ensemble averaged continuity and momentum equations for each species are derived based on the Liouville equation of the system. The ensemble average used is species specific. It is found that the interaction between species results in not only the interspecies force but also a stress in the momentum equations. In the limit that particles of one of the species can be considered as a continuum, the existence of the interspecies stress enables us to reduce the derived equations to the familiar form for dispersed two-phase flows.

  5. Binary classification of real sequences by discrete-time systems

    Science.gov (United States)

    Kaliski, M. E.; Johnson, T. L.

    1979-01-01

    This paper considers a novel approach to coding or classifying sequences of real numbers through the use of (generally nonlinear) finite-dimensional discrete-time systems. This approach involves a finite-dimensional discrete-time system (which we call a real acceptor) in cascade with a threshold type device (which we call a discriminator). The proposed classification scheme and the exact nature of the classification problem are described, along with two examples illustrating its applicability. Suggested approaches for further research are given.

  6. Eccentricity evolution in hierarchical triple systems with eccentric outer binaries

    CERN Document Server

    Georgakarakos, Nikolaos

    2014-01-01

    We develop a technique for estimating the inner eccentricity in hierarchical triple systems, with the inner orbit being initially circular, while the outer one is eccentric. We consider coplanar systems with well separated components and comparable masses. The derivation of short period terms is based on an expansion of the rate of change of the Runge-Lenz vector. Then, the short period terms are combined with secular terms, obtained by means of canonical perturbation theory. The validity of the theoretical equations is tested by numerical integrations of the full equations of motion.

  7. Planetary Systems Around Spectroscopic Binary Stars: The Very Dusty, Old, Sun-like BD+20 307

    Science.gov (United States)

    Zuckerman, Ben M.; Fekel, F. C.; Williamson, M. H.; Henry, G. W.; Muno, M. P.; Melis, C.; Marois, C.

    2009-01-01

    Field star BD+20 307 is the dustiest known main sequence star, based on the fraction of its bolometric luminosity, 4%, emitted at infrared wavelengths (Song et al. 2005; Rhee et al. 2008). The temperature of the particles that carry this large IR luminosity is comparable to that of the Sun's zodiacal dust, and their existence is likely a consequence of a fairly recent collision of large objects such as planets or planetary embryos. BD+20 307 is now known to be a 3.4 day spectroscopic binary composed of two nearly equal solar-mass stars (Weinberger 2008; Zuckerman et al. 2008). Consideration of various age indicators implies that that star is likely to be at least one Gyr old, perhaps many Gyr old. Probably the dust around this close binary star has nothing to do with planet formation and everything to do with some major catastrophic event that recently took place near 1 AU in a mature planetary system. Destabilizing planetary orbits in an old system with a single star at its center appears to be possible, e.g., Mercury (Batygin & Laughlin 2008 and references therein). Destabilization may be easier to achieve in a close binary star system and easier yet in a triple star system. Tokovinin et al. (2006) conclude that, for a spectroscopic binary star with an orbital period of 3.4 days, the probability is 70% that a third star is present. Thus, we have searched for such a tertiary star in the BD+20 307 system using accurate radial velocities measured at Fairborn and Lick observatories and with adaptive optics imaging at Keck observatory. As of the writing of this abstract, no third star is detected. Limits on mass and semimajor axis of any tertiary star will be discussed. This research was supported by a grant from the Chandra X-ray Observatory.

  8. Study of surface tension and surface properties of binary systems of DMSO with long chain alcohols at various temperatures

    International Nuclear Information System (INIS)

    Highlights: • Surface tension of binary mixtures of alcohol/DMSO determined. • Surface mole fraction and surface thermodynamic parameters were calculated. • The surface tension data of binary mixtures were correlated with FLW, LWW and MS models. -- Abstract: Surface tensions of binary mixtures of DMSO (dimethyl sulphoxide) with a series of long chain aliphatic alcohols (1-propanol, 1-butanol, and 1-hexanol) were measured as a function of composition using the ring detachment method in the temperature range between (288.15 and 328.15) K. The surface tension results are used to describe quantitatively the nature, properties, and compositions of surface layers in binary liquid mixtures. The temperature influence on the behaviour of surface tensions and surface properties of binary mixtures has often been used to obtain information about solute structural effects on DMSO. The surface tension of the above mentioned binary systems were correlated with empirical and thermodynamic based models. The average relative error obtained from the comparison of experimental and calculated surface tension values for 15 binary systems with three models is less than 1%. In addition to finding more information about the surface structure of binary mixtures, surface mole fraction was calculated using an extended Langmuir model (EL). The temperature dependence of σ at fixed composition of solutions was used to estimate surface enthalpy, Hs, and surface entropy, Ss. The results provide information on the molecular interactions between the unlike molecules that exist at the surface and the bulk

  9. Theory of Random Anisotropic Magnetic Alloys

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1976-01-01

    A mean-field-crystal-field theory is developed for random, multicomponent, anisotropic magnetic alloys. It is specially applicable to rare-earth alloys. A discussion is given of multicritical points and phase transitions between various states characterized by order parameters with different...... spatial directions or different ordering wave vectors. Theoretical predictions based on known parameters for the phase diagrams and magnetic moments for the binary rare-earth alloys of Tb, Dy, Ho, and Er, Tb-Tm, Nd-Pr, and pure double-hcp Nd agree qualitatively with the experimental observations....... Quantitative agreement can be obtained by increasing the interaction between different alloy elements, in particular for alloys with very different axial anisotropy, e.g., Tb-Tm. A model system consisting of a singlet-singlet and singlet-doublet alloy is discussed in detail. A simple procedure to include...

  10. Trajectory exploration within asynchronous binary asteroid systems using refined Lagrangian coherent structures

    Science.gov (United States)

    Shang, Haibin; Wu, Xiaoyu; Cui, Pingyuan

    2016-09-01

    Ground observations have found that asynchronous systems constitute most of the population of the near-Earth binary asteroids. This paper concerns the trajectory of a particle in the asynchronous system which is systematically described using periodic ellipsoidal and spherical body models. Due to the non-autonomous characteristics of the asynchronous system, Lagrangian coherent structures (LCS) are employed to identify the various dynamical behaviors. To enhance the accuracy of LCS, a robust LCS finding algorithm is developed incorporating hierarchical grid refinement, one-dimensional search and variational theory verification. In this way, the intricate dynamical transport boundaries are detected efficiently. These boundaries indicate that a total of 15 types of trajectories exist near asynchronous binary asteroids. According to their Kepler energy variations, these trajectories can be grouped into four basic categories, i.e., transitory, escape, impact and flyby trajectories. Furthermore, the influence of the ellipsoid's spin period on the dynamical behavior is discussed in the context of the change of dynamical regions. We found that the transitory and impact motions occur easily in the synchronous-like binary systems, in which the rotation period of the ellipsoid is nearly equal to that of the mutual orbit. Meanwhile, the results confirm a positive correlation between the spinning rate of the ellipsoid and the probability of the escape and flyby trajectories. The LCS also reveal a marked increase in trajectory diversity after a larger initial energy is selected.

  11. The parameters of binary black hole system in PKS 1510-089

    Institute of Scientific and Technical Information of China (English)

    Li Juan; Fan Jun-Hui; Yuan Yu-Hai

    2007-01-01

    Observations of PKS 1510-089 indicate the existence of a deep flux minimum with a timescale of ~35 min and an interval of about 336±14 d. A binary black hole system is proposed to be at the nucleus of this object. The secondary black hole orbits around the primary black hole.The minimum is caused by the periodic eclipse of the primary black hole by the secondary black hole.Based on the observations of PKS 1510-089,we estimate the parameters of the binary black hole system.The masses for the primary and secondary black holes are 1.37×109M⊙(M⊙ is the solar mass) and 1.37×107M⊙,and the major axis for this pair being about 0.1 parsec(pc).

  12. Error correcting codes for binary unitary channels on multipartite quantum systems

    CERN Document Server

    Choi, M D; Kribs, D W; Zyczkowski, K; Choi, Man-Duen; Holbrook, John A.; Kribs, David W.; Zyczkowski, Karol

    2006-01-01

    We conduct an analysis of ideal error correcting codes for randomized unitary channels determined by two unitary error operators -- what we call ``binary unitary channels'' -- on multipartite quantum systems. In a wide variety of cases we give a complete description of the code structure for such channels. Specifically, we find a practical geometric technique to determine the existence of codes of arbitrary dimension, and then derive an explicit construction of codes of a given dimension when they exist. For instance, given any binary unitary noise model on an n-qubit system, we design codes that support n-2 qubits. We accomplish this by verifying a conjecture for higher rank numerical ranges of normal operators in many cases.

  13. Markov-Binary Visibility Graph: a new method for analyzing Complex Systems

    CERN Document Server

    Sadra, Yaser; Ahadpour, Sodief

    2011-01-01

    In this work, we introduce a new and simple transformation from time series to complex networks based on markov-binary visibility graph(MBVG). Due to the simple structure of this transformation in comparison with other transformations be obtained more precise results. Moreover, several topological aspects of the constructed graph, such as degree distribution, clustering coefficient, and mean visibility length have been thoroughly investigated. Numerical simulations confirm the reliability of markov-binary visibility graph for time series analysis. This algorithm have the capability of distinguishing between uncorrelated and correlated systems. Finaly, we illustrate this algorithm analyzing the human heartbeat dynamics. The results indicate that the human heartbeat (RR-interval) time series of normally, Congestive Heart Failure (CHF) and Atrial Fibrillation (AF) subjects are uncorrelated, chaotic and correlated stochastic systems, respectively.

  14. DSC study of phase transitions of cephalin pseudo-binary systems in excess water

    Institute of Scientific and Technical Information of China (English)

    王邦宁; 谈夫

    1999-01-01

    The gel-liquid crystal phase transitions of the pseudo-binary systems of cephalins DMPE and DHPE in excess water were studied by differential scanning calorimetry. The phase diagram of the pseudo-binary systems has been given. The experiments showed that the partial phase separation in gel phase might occur at least at the mole fractions of DHPE below 0.1. The analysis by the model of ideal solution showed that both the cephalins were non-ideally miscible both in the gel phases and in the liquid crystal phases. The analysis by the model of regular solution showed that all the non-ideality parameters in the gel phases were larger than those in the liquid crystal phases at the same temperature. All the non-ideality parameters were not constant, but rather dependent on temperature.

  15. Determination and Prediction of Binary Solubility for Aromatic-Tetraethylene Glycol (with Water) Systems

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The binary solubilities of tetraethylene glycol (TTEG) with benzene, toluene or p-xylene, were measured by the turbidity point method. In TTEG the content of water ranged from 0 to 5% and the test temperature ranged from 20℃ to 120℃. Increasing the temperature resulted in greater solubility of the aromatics in TTEG, while increasing the content of water caused the aromatic solubility to decrease. The benzene solubillity in TTEG was the greatest followed by toluene and xylene at the same water content and temperature. The mutual solubility was predicted by correlating the paramaters of a new group for the UNIFAC model for the aromatics extraction system. The modified UNIFAC group contribution model was used to predict the binary solubility of TTEG and aromatics. The average deviation between the experimental result and prediction is 4.06%. Therefore, the UNIFAC model can be used to describe the solubility phenomena for TTEG-aromatics systems.

  16. Thermal Diffusion in binary Surfactant Systems and Microemulsions

    OpenAIRE

    Arlt, B.

    2012-01-01

    In dieser Arbeit haben wir das Thermodiffusionsverhalten von mizellaren Systemen und Mikroemulsionen untersucht. Beide Systeme werden als Modellsysteme genutzt um zwei Fragestellungen zu beantworten. Die erste Fragestellung bezieht sich auf den Einfluss der Mizellenbildung nahe der kritischen Mizellenkonzentration (cmc) auf das Thermodiffusionsverhalten. Dazu untersuchen wir das Thermodiffusionsverhalten des nichtionischen Tensides n-Octyl beta-D-Glucopyranoside (C8G1) in Wasser, welches e...

  17. Direct Observation of Defect Range and Evolution in Ion-Irradiated Single Crystalline Ni and Ni Binary Alloys

    Science.gov (United States)

    Lu, Chenyang; Jin, Ke; Béland, Laurent K.; Zhang, Feifei; Yang, Taini; Qiao, Liang; Zhang, Yanwen; Bei, Hongbin; Christen, Hans M.; Stoller, Roger E.; Wang, Lumin

    2016-02-01

    Energetic ions have been widely used to evaluate the irradiation tolerance of structural materials for nuclear power applications and to modify material properties. It is important to understand the defect production, annihilation and migration mechanisms during and after collision cascades. In this study, single crystalline pure nickel metal and single-phase concentrated solid solution alloys of 50%Ni50%Co (NiCo) and 50%Ni50%Fe (NiFe) without apparent preexisting defect sinks were employed to study defect dynamics under ion irradiation. Both cross-sectional transmission electron microscopy characterization (TEM) and Rutherford backscattering spectrometry channeling (RBS-C) spectra show that the range of radiation-induced defect clusters far exceed the theoretically predicted depth in all materials after high-dose irradiation. Defects in nickel migrate faster than in NiCo and NiFe. Both vacancy-type stacking fault tetrahedra (SFT) and interstitial loops coexist in the same region, which is consistent with molecular dynamics simulations. Kinetic activation relaxation technique (k-ART) simulations for nickel showed that small vacancy clusters, such as di-vacancies and tri-vacancies, created by collision cascades are highly mobile, even at room temperature. The slower migration of defects in the alloy along with more localized energy dissipation of the displacement cascade may lead to enhanced radiation tolerance.

  18. System and method of forming nanostructured ferritic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dial, Laura Cerully; DiDomizio, Richard; Alinger, Matthew Joseph; Huang, Shenyan

    2016-07-26

    A system for mechanical milling and a method of mechanical milling are disclosed. The system includes a container, a feedstock, and milling media. The container encloses a processing volume. The feedstock and the milling media are disposed in the processing volume of the container. The feedstock includes metal or alloy powder and a ceramic compound. The feedstock is mechanically milled in the processing volume using metallic milling media that includes a surface portion that has a carbon content less than about 0.4 weight percent.

  19. Measuring the spin of black holes in binary systems using gravitational waves.

    Science.gov (United States)

    Vitale, Salvatore; Lynch, Ryan; Veitch, John; Raymond, Vivien; Sturani, Riccardo

    2014-06-27

    Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground-based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions and the opportunity of measuring spins directly through GW observations. In this Letter, we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientations, and signal-to-noise ratios, as detected by an advanced LIGO-Virgo network. We find that for moderate or high signal-to-noise ratio the spin magnitudes can be estimated with errors of a few percent (5%-30%) for neutron star-black hole (black hole-black hole) systems. Spins' tilt angle can be estimated with errors of 0.04 rad in the best cases, but typical values will be above 0.1 rad. Errors will be larger for signals barely above the threshold for detection. The difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum and that a sudden change of behavior occurs when a system is observed from angles such that the plane of the orbit can be seen both from above and below during the time the signal is in band. This study suggests that direct measurement of black hole spin by means of GWs can be as precise as what can be obtained from x-ray binaries.

  20. Measuring the spin of black holes in binary systems using gravitational waves.

    Science.gov (United States)

    Vitale, Salvatore; Lynch, Ryan; Veitch, John; Raymond, Vivien; Sturani, Riccardo

    2014-06-27

    Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground-based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions and the opportunity of measuring spins directly through GW observations. In this Letter, we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientations, and signal-to-noise ratios, as detected by an advanced LIGO-Virgo network. We find that for moderate or high signal-to-noise ratio the spin magnitudes can be estimated with errors of a few percent (5%-30%) for neutron star-black hole (black hole-black hole) systems. Spins' tilt angle can be estimated with errors of 0.04 rad in the best cases, but typical values will be above 0.1 rad. Errors will be larger for signals barely above the threshold for detection. The difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum and that a sudden change of behavior occurs when a system is observed from angles such that the plane of the orbit can be seen both from above and below during the time the signal is in band. This study suggests that direct measurement of black hole spin by means of GWs can be as precise as what can be obtained from x-ray binaries. PMID:25014800

  1. Heat Transfer of Single and Binary Systems inPool Boiling

    OpenAIRE

    Abbas J. Sultan; Balasim A. Abid

    2010-01-01

    The present research focuses on the study of the effect of mass transfer resistance on the rate of heat transfer in pool boiling. The nucleate pool boiling heat transfer coefficients for binary mixtures (ethanol-n-butanol, acetone-n-butanol, acetone-ethanol, hexane-benzene, hexane-heptane, and methanol-water) were measured at different concentrations of the more volatile components. The systems chosen covered a wide range of mixture behaviors.The experimental set up for the present investigat...

  2. Evaluated phase diagrams of binary metal-tellurium systems of the D-block transition elements

    International Nuclear Information System (INIS)

    The binary phase diagrams of metal-tellurium systems for twenty seven d-block transition elements have been critically evaluated. Complete phase diagrams are presented for the elements, chromium, manganese, iron, cobalt, nickel, copper, molybdenum, palladium, silver, lanthanum, platinum and gold, whereas, for scandium, titanium, vanadium, yttrium, zirconium, niobium, technitium, ruthenium, rhodium, hafnium, tantalum, tungsten , rhenium, osmium and iridium, the phase diagrams are incomplete and tentative. (author). 20 refs., 27 tabs., 27 figs

  3. Thermal degradation features of peppermint oil in a binary system with Β- cyclodextrin

    OpenAIRE

    Omelchenko, I. A.; Yarnykh, T. G.; Yanchuk, I. B.; Bоrschevskiy, G. I.

    2016-01-01

    Aim. One of the most promising ways of changing physical and chemical properties of the active pharmaceutical ingredient is an encapsulation on a molecular level with the use of cyclodextrins. This makes it possible to create products with the desired activity and controlled distribution in the body.Methods and results. We have studied the thermal decomposition of peppermint oil in binary systems with β-cyclodextrin. It has been found that the thermal degradation of mechanical mixture and inc...

  4. Structure and Spectrum of Binary Classic Systems Confined in a Parabolic Trap

    Institute of Scientific and Technical Information of China (English)

    YANG Wen; ZENG Zhi

    2009-01-01

    @@ The static and dynamic properties of the two-dimensional classic system of two-species interacting charged par-ticles in a parabolic trap are studied. The ground state energy and configuration for different kinds of binary systems are obtained by Monte Carlo simulation and Newton optimization. The spectrum and normal modes vectors can be gained by diagonalizing the dynamical matrix of the system. It is found that the total particle number, particle number and mass-to-charge ratio of each species are decisive factors for the system structure and spectrum. The three intrinsic normal modes of single species Coulomb clusters are inherent, concluded from our numerical simulations and analytical results.

  5. Polyphase alloys as rechargeable electrodes in advanced battery systems

    Science.gov (United States)

    Huggins, Robert A.

    1987-01-01

    The rechargeability of electrochemical cells is often limited by negative electrode problems. These may include loss of capacity, increased impedance, macroscopic shape change, dendrite growth, or a tendency for filamentary or whisker growth. In principle, these problems can be reduced or eliminated by the use of alloys that undergo either displacement or insertion reactions at reactant species activities less than unity, rather than pure elements. The fundamental reasons for some of these problems with elemental electrodes, as well as the basic principles involved in the different behavior of alloys, are briefly discussed. More information is now available concerning the thermodynamic and kinetic properties of a number of alloys of potential interest for use as electrodes in elevated temperature lithium battery systems. Recent results have extended these results down to ambient temperatures, indicating that some such materials may be of interest for use with new low temperature molten salt electrolytes, or with organic solvent electrolytes. The all solid mixed conductor matrix concept is also reviewed.

  6. Windtalking Computers: Frequency Normalization, Binary Coding Systems and Encryption

    CERN Document Server

    Zirkind, Givon

    2009-01-01

    The goal of this paper is to discuss the application of known techniques, knowledge and technology in a novel way, to encrypt computer and non-computer data. To-date most computers use base 2 and most encryption systems use ciphering and/or an encryption algorithm, to convert data into a secret message. The method of having the computer "speak another secret language" as used in human military secret communications has never been imitated. The author presents the theory and several possible implementations of a method for computers for secret communications analogous to human beings using a secret language or; speaking multiple languages. The kind of encryption scheme proposed significantly increases the complexity of and the effort needed for, decryption. As every methodology has its drawbacks, so too, the data of the proposed system has its drawbacks. It is not as compressed as base 2 would be. However, this is manageable and acceptable, if the goal is very strong encryption: At least two methods and their ...

  7. Thermodynamic assessment of the Pd–Y binary system

    Directory of Open Access Journals (Sweden)

    Kardellass S.

    2013-09-01

    Full Text Available The Pd–Y system was critically assessed using the CALPHAD technique. The solution phases (liquid, b.c.c., f.c.c. and h.c.p. were modeled using the Redlich–Kister equation. The intermetallic compounds Pd3Y and PdY, which have homogeneity ranges, were treated as the formula (Pd,Y0.75(Pd,Y0.25 and (Pd,Y0.5(Pd,Y0.5 by a two-sublattice model with a mutual substitution of Pd and Y on both sublattices. The optimization was carried out in two steps. In the first treatment, Pd3Y and PdY are assumed to be stoichiometric compounds; in the second treatment they are treated by a sublattice model. The parameters obtained from the first treatment were used as starting values for the second treatment. The calculated phase diagram and the thermodynamic properties of the system are in satisfactory agreement with the experimental data.

  8. Colliding Winds in Low-Mass Binary Star Systems: wind interactions and implications for habitable planets

    CERN Document Server

    Johnstone, C P; Pilat-Lohinger, E; Bisikalo, D; Güdel, M; Eggl, S

    2015-01-01

    Context. In binary star systems, the winds from the two components impact each other, leading to strong shocks and regions of enhanced density and temperature. Potentially habitable circumbinary planets must continually be exposed to these interactions regions. Aims. We study, for the first time, the interactions between winds from low-mass stars in a binary system, to show the wind conditions seen by potentially habitable circumbinary planets. Methods. We use the advanced 3D numerical hydrodynamic code Nurgush to model the wind interactions of two identical winds from two solar mass stars with circular orbits and a binary separation of 0.5 AU. As input into this model, we use a 1D hydrodynamic simulation of the solar wind, run using the Versatile Advection Code. We derive the locations of stable and habitable orbits in this system to explore what wind conditions potentially habitable planets will be exposed to during their orbits. Results. Our wind interaction simulations result in the formation of two stron...

  9. New Pleiades Eclipsing Binaries and a Hyades Transiting System Identified by K2

    CERN Document Server

    David, Trevor J; Hillenbrand, Lynne A; Stassun, Keivan G; Stauffer, John; Rebull, Luisa M; Cody, Ann Marie; Isaacson, Howard; Howard, Andrew W; Aigrain, Suzanne

    2016-01-01

    We present the discovery in Kepler's $K2$ mission observations and our follow-up radial velocity observations from Keck/HIRES for four eclipsing binary (EB) star systems in the young benchmark Pleiades cluster. Based on our modeling results, we announce two new low mass ($M_{tot} < 0.6 M_\\odot$) EBs among Pleiades members (HCG 76 and MHO 9) and we report on two previously known Pleiades binaries that are also found to be EB systems (HII 2407 and HD 23642). We measured the masses of the binary HCG 76 to $\\lesssim$2.5% precision, and the radii to $\\lesssim$4.5% precision, which together with the precise effective temperatures yield an independent Pleiades distance of 132$\\pm$5 pc. We discuss another EB towards the Pleiades that is a possible but unlikely Pleiades cluster member (AK II 465). The two new confirmed Pleiades systems extend the mass range of Pleiades EB components to 0.2-2 $M_\\odot$. Our initial measurements of the fundamental stellar parameters for the Pleiades EBs are discussed in the context o...

  10. Polar pattern formation in driven filament systems requires non-binary particle collisions

    Science.gov (United States)

    Suzuki, Ryo; Weber, Christoph A.; Frey, Erwin; Bausch, Andreas R.

    2015-10-01

    From the self-organization of the cytoskeleton to the synchronous motion of bird flocks, living matter has the extraordinary ability to behave in a concerted manner. The Boltzmann equation for self-propelled particles is frequently used in silico to link a system’s meso- or macroscopic behaviour to the microscopic dynamics of its constituents. But so far such studies have relied on an assumption of simplified binary collisions owing to a lack of experimental data suggesting otherwise. We report here experimentally determined binary-collision statistics by studying a recently introduced molecular system, the high-density actomyosin motility assay. We demonstrate that the alignment induced by binary collisions is too weak to account for the observed ordering transition. The transition density for polar pattern formation decreases quadratically with filament length, indicating that multi-filament collisions drive the observed ordering phenomenon and that a gas-like picture cannot explain the transition of the system to polar order. Our findings demonstrate that the unique properties of biological active-matter systems require a description that goes well beyond that developed in the framework of kinetic theories.

  11. Observations of TeV binary systems with the H.E.S.S. telescope

    CERN Document Server

    Bordas, Pol; de Naurois, Mathieu; Ohm, Stefan; Wilhelmi, Emma de Oña; Sushch, Iurii; Volpe, Francesca; Zabalza, Víctor

    2013-01-01

    Recent observations of binary systems obtained with the H.E.S.S. telescopes are providing crucial information on the physics of relativistic outflows and the engines powering them. We report here on new H.E.S.S. results on HESS J0632+057, PSR B1259-63/LS 2883, Eta Carinae and the recently discovered source HESS J1018-589. Despite the high-quality data obtained in the last years through both ground and space-based gamma-ray detectors, many questions on the mechanisms that permit binary systems to emit at gamma-rays remain open. In particular, it is becoming apparent that emission at high and very-high energies is uncorrelated in some gamma-ray binary systems, with bright GeV flares not observed at TeV energies (e.g. PSR B1259-63), and sources periodically detected at VHEs which are lacking its HE counterpart (e.g. HESS J0632+057). Our results mainly confirm the predictions derived previously for the studied sources, but unexpected results are also found in a few cases, which are discussed in the context of con...

  12. Eclipse timing variations to detect possible Trojan planets in binary systems

    CERN Document Server

    Schwarz, R; Funk, B; Zechner, R

    2016-01-01

    This paper is devoted to study the circumstances favourable to detect Trojan planets in close binary-star-systems by the help of eclipse timing variations (ETVs). To determine the probability of the detection of such variations with ground based telescopes and space telescopes (like former missions CoRoT and Kepler and future space missions like Plato, Tess and Cheops), we investigated the dynamics of binary star systems with a planet in tadpole motion. We did numerical simulations by using the full three-body problem as dynamical model. The stability and the ETVs are investigated by computing stability/ETV maps for different masses of the secondary star and the Trojan planet. In addition we changed the eccentricity of the possible Trojan planet. By the help of the libration amplitude $\\sigma$ we could show whether or not all stable objects are moving in tadpole orbits. We can conclude that many amplitudes of ETVs are large enough to detect Earth-like Trojan planets in binary star systems. As an application, ...

  13. A 3D dynamical model of the colliding winds in binary systems

    CERN Document Server

    Parkin, E R

    2008-01-01

    We present a 3D dynamical model of the orbital induced curvature of the wind-wind collision region in binary star systems. Momentum balance equations are used to determine the position and shape of the contact discontinuity between the stars, while further downstream the gas is assumed to behave ballistically. An archimedean spiral structure is formed by the motion of the stars, with clear resemblance to high resolution images of the so-called ``pinwheel nebulae''. A key advantage of this approach over grid or smoothed particle hydrodynamic models is its significantly reduced computational cost, while it also allows the study of the structure obtained in an eccentric orbit. The model is relevant to symbiotic systems and Gamma-ray binaries, as well as systems with O-type and Wolf-Rayet stars. As an example application, we simulate the X-ray emission from hypothetical O+O and WR+O star binaries, and describe a method of ray tracing through the 3D spiral structure to account for absorption by the circumstellar m...

  14. Accretion, Ablation and Propeller Evolution in Close Millisecond Pulsar Binary Systems

    CERN Document Server

    Kiel, P D

    2013-01-01

    A model for the formation and evolution of binary millisecond radio pulsars in systems with low mass companions (< 0.1 Msun) is investigated using a binary population synthesis technique. Taking into account the non conservative evolution of the system due to mass loss from an accretion disk as a result of propeller action and from the companion via ablation by the pulsar, the transition from the accretion powered to rotation powered phase is investigated. It is shown that the operation of the propeller and ablation mechanisms can be responsible for the formation and evolution of black widow millisecond pulsar systems from the low mass X-ray binary phase at an orbital period of ~0.1 day. For a range of population synthesis input parameters, the results reveal that a population of black widow millisecond pulsars characterized by orbital periods as long as ~0.4 days and companion masses as low as ~0.005 Msun can be produced. The orbital periods and minimum companion mass of this radio millisecond pulsar popu...

  15. Stability and Fourier-series periodic solution in the binary stellar systems

    CERN Document Server

    Mia, Rajib

    2016-01-01

    In this paper, we use the restricted three body problem in the binary stellar systems, taking photogravitational effects of both the stars. The aim of this study is to investigate the motion of the infinitesimal mass in the vicinity of the Lagrangian points. We have computed semi-analytical expressions for the locations of the collinear points with the help of the perturbation technique. The stability of the triangular points is studied in stellar binary systems Kepler-34, Kepler-35, Kepler-413 and Kepler-16. To investigate the stability of the triangular points, we have obtained the expressions for critical mass which depends on the radiation of both primaries. Fourier-series method is applied to obtain periodic orbits of the infinitesimal mass around triangular points in binary stellar systems. We have obtained Fourier expansions of the periodic orbits around triangular points upto third order terms. A comparison is made between periodic orbits obtained by Fourier-series method and with Runge-Kutta integrat...

  16. Detection of a white dwarf in a visual binary system

    Science.gov (United States)

    Boehm-Vitense, Erika

    1980-01-01

    The F6 giant HD 160365 was detected to have a white dwarf companion about 8 arcsec south of the star. The UV energy distribution observed with International Ultraviolet Explorer (IUE) shows that the white dwarf has an effective temperature of 23,000 +/- 2,000 K. If log g = 8 the Ly(alpha) profile indicates an effective temperature around 24,500 K. Using the theoretical models, one finds a visual magnitude of m(sub v) is approximately 16.5. For T(sub eff) = 24,500 K one expects for a white dwarf a luminosity of log L/solar luminosity is approximately -1.3 and M(sub V) is approximately 10.67. This gives a distance modulus for the system of m(sub v) - M(sub V) = 5.83 and an absolute magnitude M(sub v) = 0.3 for the giant.

  17. A phase-field-lattice Boltzmann method for modeling motion and growth of a dendrite for binary alloy solidification in the presence of melt convection

    Science.gov (United States)

    Rojas, Roberto; Takaki, Tomohiro; Ohno, Munekazu

    2015-10-01

    In this study, a combination of the lattice Boltzmann method (LBM) and the phase-field method (PFM) is used for modeling simultaneous growth and motion of a dendrite during solidification. PFM is used as a numerical tool to simulate the morphological changes of the solid phase, and the fluid flow of the liquid phase is described by using LBM. The no-slip boundary condition at the liquid-solid interface is satisfied by adding a diffusive-forcing term in the LBM formulation. The equations of motion are solved for tracking the translational and rotational motion of the solid phase. The proposed method is easily implemented on a single Cartesian grid and is suitable for parallel computation. Two-dimensional benchmark computations show that the no-slip boundary condition and the shape preservation condition are satisfied in this method. Then, the present method is applied to the calculation of dendritic growth of a binary alloy under melt convection. Initially, the solid is stationary, and then, the solid moves freely due to the influence of fluid flow. Simultaneous growth and motion are effectively simulated. As a result, it is found that motion and melt convection enhance dendritic growth along the flow direction.

  18. Predicting Pathways for Synthesis of Ferromagnetic τ Phase in Binary Heusler Alloy Al-55 pct Mn Through Understanding of the Kinetics of ɛ-τ Transformation

    Science.gov (United States)

    Palanisamy, Dhanalakshmi; Singh, Shailesh; Srivastava, Chandan; Madras, Giridhar; Chattopadhyay, Kamanio

    2016-09-01

    This paper outlines the detailed procedure for the synthesis of pure ferromagnetic τ phase in binary Heusler Al-55 pct Mn alloy in bulk form through casting route without any addition of stabilizers. To obtain the processing domain for the formation of the τ phase from high-temperature ɛ phase, isothermal transformation experiments were carried out. The structure and microstructure were characterized by X-ray diffraction and electron microscopy studies. The τ phase start times were obtained through magnetic measurements. In order to tune the casting conditions for the formation of this phase, thermal modeling was carried out to predict the heat extraction rates for copper molds of different diameters (2 to 12 mm) containing hot solids during casting process. This enabled us to estimate the diameter of the mold to be used for obtaining τ phase directly during casting. It was concluded through experimental verification that 10-mm-diameter casting in copper mold is suitable to obtain complete τ phase. A saturation magnetization of 116 emu/g at 10 K was measured for such samples. The Curie point for the τ phase was found to be 668 K (395 °C). Additionally, the cast rod exhibits a compressive strength of 1170 MPa which is higher than those of both ferrites and AlNiCo magnets.

  19. The potential of phase change materials for thermoelectric applications - An investigation of alloys along the pseudo binary line from GeTe to SnTe

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Felix; Volker, Hanno; Siegert, Karl Simon; Wuttig, Matthias [1. Physikalisches Institut IA, RWTH Aachen University (Germany)

    2011-07-01

    Thermoelectric generators make use of the Seebeck effect which is an intrinsic property of any non dielectric solid. Materials with a high conversion efficiency are characterized by a high figure-of-merit ZT={sigma} S{sup 2}/{kappa}, where {sigma} is the electrical conductivity, S the Seebeck coefficient and {kappa} the thermal conductivity. We have recently shown that phase change materials employ resonant bonding which results in a delocalization of carriers and an anharmonic potential. The delocalization of carriers leads to high electrical conductivity while the anharmonic potential enhances the probability for phonon-phonon interactions such as umklapp processes. Hence, phase change materials are promising candidates for thermoelectric applications. Therefore alloys along the pseudo binary line from GeTe to SnTe are investigated. It is shown, that the electrical conductivity can be tailored by gradually adding Sn. The disorder on the Ge-Sn sublattice causes a low thermal conductivity which develops a minimum for Ge{sub 2}Sn{sub 2}Te{sub 4}.

  20. The potential of phase change materials for thermoelectric applications - An investigation of alloys along the pseudo binary line from GeTe to SnTe

    International Nuclear Information System (INIS)

    Thermoelectric generators make use of the Seebeck effect which is an intrinsic property of any non dielectric solid. Materials with a high conversion efficiency are characterized by a high figure-of-merit ZT=σ S2/κ, where σ is the electrical conductivity, S the Seebeck coefficient and κ the thermal conductivity. We have recently shown that phase change materials employ resonant bonding which results in a delocalization of carriers and an anharmonic potential. The delocalization of carriers leads to high electrical conductivity while the anharmonic potential enhances the probability for phonon-phonon interactions such as umklapp processes. Hence, phase change materials are promising candidates for thermoelectric applications. Therefore alloys along the pseudo binary line from GeTe to SnTe are investigated. It is shown, that the electrical conductivity can be tailored by gradually adding Sn. The disorder on the Ge-Sn sublattice causes a low thermal conductivity which develops a minimum for Ge2Sn2Te4.

  1. AL Cassiopeiae: An F-type Contact Binary System with a Cool Stellar Companion

    Science.gov (United States)

    Qian, S.-B.; Zhou, X.; Zola, S.; Zhu, L.-Y.; Zhao, E.-G.; Liao, W.-P.; Leung, K.-C.

    2014-11-01

    According to the general catalog of variable stars, AL Cas was classified as an EW-type eclipsing binary with a spectral type of B and an orbital period of P = 0.5005555 days. The first photometric light curves of the close binary in the B, V, R, and I bands are presented. New low-resolution spectra indicate that its spectral type is about F7 rather than B-type. A photometric analysis with the Wilson-Devinney method suggests that it is a contact binary (f = 39.3%) with a mass ratio of 0.61. Using 17 newly determined eclipse times together with those collected from the literature, we found that the observed-calculated (O - C) curve of AL Cas shows a cyclic change with a period of 86.6 yr and an amplitude of 0.0181 days. The periodic variation was analyzed for the light-travel time effect via the presence of a third body. The mass of the third body was determined to be M 3sin i' = 0.29(± 0.05) M ⊙ when a total mass of 2.14 M ⊙ for AL Cas is adopted. It is expected that the cool companion star may have played an important role in the origin and evolution of the system by removing angular momentum from the central binary system during early dynamical interaction and/or late dynamical evolution. This causes the original detached system to have a low angular momentum and a short initial orbital period. Then it can evolve into the present contact configuration via a case A mass transfer.

  2. AL Cassiopeiae: An F-type contact binary system with a cool stellar companion

    International Nuclear Information System (INIS)

    According to the general catalog of variable stars, AL Cas was classified as an EW-type eclipsing binary with a spectral type of B and an orbital period of P = 0.5005555 days. The first photometric light curves of the close binary in the B, V, R, and I bands are presented. New low-resolution spectra indicate that its spectral type is about F7 rather than B-type. A photometric analysis with the Wilson-Devinney method suggests that it is a contact binary (f = 39.3%) with a mass ratio of 0.61. Using 17 newly determined eclipse times together with those collected from the literature, we found that the observed–calculated (O – C) curve of AL Cas shows a cyclic change with a period of 86.6 yr and an amplitude of 0.0181 days. The periodic variation was analyzed for the light-travel time effect via the presence of a third body. The mass of the third body was determined to be M 3sin i' = 0.29(± 0.05) M ☉ when a total mass of 2.14 M ☉ for AL Cas is adopted. It is expected that the cool companion star may have played an important role in the origin and evolution of the system by removing angular momentum from the central binary system during early dynamical interaction and/or late dynamical evolution. This causes the original detached system to have a low angular momentum and a short initial orbital period. Then it can evolve into the present contact configuration via a case A mass transfer.

  3. Constructing optimized binary masks for reservoir computing with delay systems.

    Science.gov (United States)

    Appeltant, Lennert; Van der Sande, Guy; Danckaert, Jan; Fischer, Ingo

    2014-01-01

    Reservoir computing is a novel bio-inspired computing method, capable of solving complex tasks in a computationally efficient way. It has recently been successfully implemented using delayed feedback systems, allowing to reduce the hardware complexity of brain-inspired computers drastically. In this approach, the pre-processing procedure relies on the definition of a temporal mask which serves as a scaled time-mutiplexing of the input. Originally, random masks had been chosen, motivated by the random connectivity in reservoirs. This random generation can sometimes fail. Moreover, for hardware implementations random generation is not ideal due to its complexity and the requirement for trial and error. We outline a procedure to reliably construct an optimal mask pattern in terms of multipurpose performance, derived from the concept of maximum length sequences. Not only does this ensure the creation of the shortest possible mask that leads to maximum variability in the reservoir states for the given reservoir, it also allows for an interpretation of the statistical significance of the provided training samples for the task at hand.

  4. Heterogeneity and subjectivity in binary-state opinion formation systems

    International Nuclear Information System (INIS)

    In society, there is heterogeneous interaction and randomness in human decision making. In order to unfold the roles and the competition of the two factors mentioned above in opinion formation, we propose a toy model, which follows a majority rule with a Fermi function, on scale-free networks with degree exponent γ. The heterogeneous interaction is related to the connectivity of a person with the interactive parameter β, and the randomness of human decision making is quantified by the interaction noise T. We find that a system with heterogeneity of network topology and interaction shows robustness perturbed by the interaction noise T according to the theoretical analysis and numerical simulation. Then, when T → 0, the homogeneous interaction (β ≃ 0) has a powerful implication for the emergence of a consensus state. Furthermore, the emergence of the two extreme values shows the competition of the heterogeneity of interaction and the subjectivity of human decision making in opinion formation. Our present work provides some perspective on and tools for understanding the diversity of opinion in our society. (paper)

  5. WZ Cygni: a Marginal Contact Binary in a Triple System?

    CERN Document Server

    Lee, Jae Woo; Lee, Chung-Uk; Kim, Ho-Il; Park, Jang-Ho; Hinse, Tobias Cornelius

    2011-01-01

    We present new multiband CCD photometry for WZ Cyg made on 22 nights in two observing seasons of 2007 and 2008. Our light-curve synthesis indicates that the system is in poor thermal contact with a fill-out factor of 4.8% and a temperature difference of 1447 K. Including our 40 timing measurements, a total of 371 times of minimum light spanning more than 112 yr were used for a period study. Detailed analysis of the $O$--$C$ diagram showed that the orbital period has varied by a combination with an upward parabola and a sinusoid. The upward parabola means the continuous period increase and indicates that some stellar masses are thermally transferred from the less to the more massive primary star at a rate of about 5.80$\\times10^{-8}$ M$_\\odot$ yr$^{-1}$. The sinusoidal variation with a period of 47.9 yr and a semi-amplitude of 0.008 d can be interpreted most likely as the light-travel-time effect due to the existence of a low-mass M-type tertiary companion with a projected mass of $M_3 \\sin i_3$=0.26 M$_\\odot$...

  6. Thermodynamic modelling of the C-U and B-U binary systems

    International Nuclear Information System (INIS)

    The thermodynamic modelling of the carbon-uranium (C-U) and boron-uranium (B-U) binary systems is being performed in the framework of the development of a thermodynamic database for nuclear materials, for increasing the basic knowledge of key phenomena which may occur in the event of a severe accident in a nuclear power plant. Applications are foreseen in the nuclear safety field to the physico-chemical interaction modelling, on the one hand the in-vessel core degradation producing the corium (fuel, zircaloy, steel, control rods) and on the other hand the ex-vessel molten corium-concrete interaction (MCCI). The key O-U-Zr ternary system, previously modelled, allows us to describe the first interaction of the fuel with zircaloy cladding. Then, the three binary systems Fe-U, Cr-U and Ni-U were modelled as a preliminary work for modelling the O-U-Zr-Fe-Cr-Ni multicomponent system, allowing us to introduce the steel components in the corium. In the existing database (TDBCR, thermodynamic data base for corium), Ag and In were introduced for modelling AIC (silver-indium-cadmium) control rods which are used in French pressurized water reactors (PWR). Elsewhere, B4C is also used for control rods. That is why it was agreed to extend in the next years the database with two new components, B and C. Such a work needs the thermodynamic modelling of all the binary and pseudo-binary sub-systems resulting from the combination of B, B2O3 and C with the major components of TDBCR, O-U-Zr-Fe-Cr-Ni-Ag-In-Ba-La-Ru-Sr-Al-Ca-Mg-Si + Ar-H. The critical assessment of the very numerous experimental information available for the C-U and B-U binary systems was performed by using a classical optimization procedure and the Scientific Group Thermodata Europe (SGTE). New optimized Gibbs energy parameters are given, and comparisons between calculated and experimental equilibrium phase diagrams or thermodynamic properties are presented. The self-consistency obtained is quite satisfactory

  7. Formation process of micro arc oxidation coatings obtained in a sodium phytate containing solution with and without CaCO{sub 3} on binary Mg-1.0Ca alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, R.F. [School of Material and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Zhang, Y.Q. [Zhejiang DunAn Light Alloy Technology CO,.LTD, Zhuji 311835 (China); Hunan University of Science and Technology, Xiangtan 411201 (China); Zhang, S.F.; Qu, B. [School of Material and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Guo, S.B. [Hunan University of Science and Technology, Xiangtan 411201 (China); Xiang, J.H., E-mail: xiangjunhuai@163.com [School of Material and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330013 (China)

    2015-01-15

    Highlights: • Compared to the Mg phase, the area of Mg{sub 2}Ca phase is much smaller. • The coatings are preferentially developed on the area adjacent to Mg{sub 2}Ca phase. • During MAO process, some sodium phytate molecules are hydrolyzed. • Anodic coatings are developed from uneven to uniform. - Abstract: Micro arc oxidation (MAO) is an effective method to improve the corrosion resistance of magnesium alloys. In order to reveal the influence of alloying element Ca and CaCO{sub 3} electrolyte on the formation process and chemical compositions of MAO coatings on binary Mg-1.0Ca alloy, anodic coatings after different anodizing times were prepared on binary Mg-1.0Ca alloy in a base solution containing 3 g/L sodium hydroxide and 15 g/L sodium phytate with and without addition of CaCO{sub 3}. The coating formation was studied by using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results show that Mg-1.0Ca alloy is composed of two phases, the Mg phase and Mg{sub 2}Ca phase. After treating for 5 s, the coating began to develop and was preferentially formed on the area nearby Mg{sub 2}Ca phase, which may be resulted from the intrinsic electronegative potential of the Mg phase than that of Mg{sub 2}Ca phase. Anodic coatings unevenly covered the total surface after 20 s. After 80 s, the coatings were uniformly developed on Mg-1.0Ca alloy with micro pores. During MAO process, some sodium phytate molecules are hydrolyzed into inorganic phosphate. CaCO{sub 3} has minor influence on the calcium content of the obtained MAO coatings.

  8. Homogeneous bubble nucleation in binary systems of liquid solvent and dissolved gas

    Science.gov (United States)

    Němec, Tomáš

    2016-03-01

    A formulation of the classical nucleation theory (CNT) is developed for bubble nucleation in a binary system composed of a liquid solvent and a dissolved gas. The theoretical predictions are compared to the experimental nucleation data of four binary mixtures, i.e. diethylether - nitrogen, propane - carbon dioxide, isobutane - carbon dioxide, and R22 (chlorodifluoromethane) - carbon dioxide. The presented CNT formulation is found to improve the precision of the simpler theoretical method of Ward et al. [J. Basic Eng. 92 (10), 71-80, 1970] based on the weak-solution approximation. By analyzing the available experimental nucleation data, an inconsistency in the data reported by Mori et al. [Int. J. Heat Mass Transfer, 19 (10), 1153-1159, 1976] for propane - carbon dioxide and R22 - carbon dioxide is identified.

  9. Light Curve Analysis for W UMa-Type Eclipsing Binary Star Systems

    Science.gov (United States)

    Henderson, Scott; Peach, N.; Olsen, T.

    2006-12-01

    We report results from summer 2006 in an ongoing study of eclipsing binary stars. Our investigations have focused on the measurement and interpretation of light curves for W UMa-type systems 44i Boötis and VW Cephei. These contact binaries have component stars of spectral type G, and revolve with periods of 6.43 and 6.67 hours. Dome automation and scripting capabilities introduced this summer have significantly reduced experimental uncertainties in our data. In support of previous findings we continue to observe an increase in the orbital period of 44i Boo at a rate of 10.4 µs/epoch or 14.2 ms/yr. Residuals computed after incorporating the increasing period suggest an underlying sinusoidal oscillation with a 61.5 year period and amplitude of 648 seconds. AAPT Member Thomas Olsen is sponsoring the lead presenter, SPS Member Scott Henderson, and the co-presenter, SPS Member Nick Peach.

  10. Automated calculation of complete Pxy and Txy diagrams for binary systems

    DEFF Research Database (Denmark)

    Cismondi, Martin; Michelsen, Michael Locht

    2007-01-01

    An algorithm for the calculation of global phase equilibrium diagrams has been recently developed [M. Cismondi, M.L. Michelsen, Global phase equilibrium calculations: critical lines, critical end points and liquid-liquid-vapour equilibrium in binary mixtures, J. Supercrit. Fluids 39 (2007) 287......-295]. It integrates the calculation of critical lines, liquid-liquid-vapour (LLV) lines and critical end points, and was implemented in the software program GPEC: global phase equilibrium calculations [M. Cismondi, D.N. Nunez, M.S. Zabaloy, E.A. Brignole, M.L. Michelsen, J.M. Mollerup, GPEC: a program for global...... phase equilibrium calculations in binary systems, in: Proceedings of the CD-ROM EQUIFASE 2006, Morelia, Michoacan, Mexico, October 21-25, 2006; www.gpec.plapiqui.edu.ar]. In this work we present the methods and computational strategy for the automated calculation of complete Pxy and Txy diagrams...

  11. Stellar Scattering and the Formation of Hot-Jupiters in Binary Systems

    CERN Document Server

    Martí, J G

    2014-01-01

    Hot Jupiters (HJs) are usually defined as giant Jovian-size planets with orbital periods $P \\le 10$ days. Although they lie close to the star, several have finite eccentricities and significant misalignment angle with respect to the stellar equator. Two mechanisms have been proposed to explain the excited and misaligned sub-population of HJs: Lidov-Kozai migration and planet-planet scattering. Although both are based on completely different dynamical phenomena, they appear to be equally effective in generating hot planets. Nevertheless, there has been no detailed analysis comparing the predictions of both mechanisms. In this paper we present numerical simulations of Lidov-Kozai trapping of single planets in compact binary systems. Both the planet and the binary are initially placed in coplanar orbits, although the inclination of the impactor is assumed random. After the passage of the third star, we follow the orbital and spin evolution of the planet using analytical models based on the octupole expansion of ...

  12. Analysis of spin precession in binary black hole systems including quadrupole-monopole interaction

    CERN Document Server

    Racine, Etienne

    2008-01-01

    We analyze in detail the spin precession equations in binary black hole systems, when the tidal torque on a Kerr black hole is taken into account. We show that completing the precession equations with this term reveals the existence of a conserved quantity at 2PN order when restricting attention to orbits with negligible eccentricity and averaging over orbital motion. This quantity allows one to solve the (orbit-averaged) precession equations exactly in the case of equal masses and arbitrary spins, neglecting radiation reaction. For unequal masses, an exact solution does not exist in closed form, but we are still able to derive accurate approximate analytic solutions. We also show how to incorporate radiation reaction effects into our analytic solutions adiabatically, and compare the results to solutions obtained numerically. For various configurations of the binary, the relative difference in the accumulated orbital phase computed using our analytic solutions versus a full numerical solution vary from about ...

  13. A novel Fingervein Recognition System based on Monogenic Local Binary Pattern Features

    Directory of Open Access Journals (Sweden)

    Alima DAMAK MASMOUDI

    2014-01-01

    Full Text Available As a new approach to human identification, fingervein recognition is becoming an active biometric recognition mode. This paper focuses on fingervein recognition system. First, a preprocessing algorithm is used to enhance each fingervein image. Then, an improvement technique of feature extraction based on Monogenic Local Binary Pattern (MLBP is presented. This novel metric integrates the conventional LBP (Local Binary Pattern with the other two rotation invariant measures (local phase and local surface type to lower the computational complexity while slightly increasing the matching accuracy. Experimental results show that the proposed algorithm offres best performances in fingervein recognition. In fact, the area under curve of proposed approach has very close to unity (0.91

  14. Eclipsing binary systems as tests of low-mass stellar evolution theory

    CERN Document Server

    Feiden, Gregory A

    2015-01-01

    Stellar fundamental properties (masses, radii, effective temperatures) can be extracted from observations of eclipsing binary systems with remarkable precision, often better than 2%. Such precise measurements afford us the opportunity to confront the validity of basic predictions of stellar evolution theory, such as the mass-radius relationship. A brief historical overview of confrontations between stellar models and data from eclipsing binaries is given, highlighting key results and physical insight that have led directly to our present understanding. The current paradigm that standard stellar evolution theory is insufficient to describe the most basic relation, that of a star's mass to its radius, along the main sequence is then described. Departures of theoretical expectations from empirical data, however, provide a rich opportunity to explore various physical solutions, improving our understanding of important stellar astrophysical processes.

  15. PLUTONIUM-THORIUM ALLOYS

    Science.gov (United States)

    Schonfeld, F.W.

    1959-09-15

    New plutonium-base binary alloys useful as liquid reactor fuel are described. The alloys consist of 50 to 98 at.% thorium with the remainder plutonium. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are easy fabrication, phase stability, and the accompanying advantuge of providing a means for converting Th/sup 232/ into U/sup 233/.

  16. Kinetics of phase growth at interdiffusion in poly-phase binary systems

    International Nuclear Information System (INIS)

    The possibility of the analytical description of phase growth kinetics in the general case of the n-phase binary system is considered. The expression is obtained, for calculating the constant of phase growth for the general case of simultaneous n phase growth in the case of mutual diffusion of metals. It is established that the growth constant in this case is a complex function of the system diffusion parameters and is also dependent upon the particular experimental conditions. Presented are the results obtained for the Nb-Pb and Ni-Mo systems

  17. On the incidence of eclipsing Am binary systems in the SuperWASP survey

    CERN Document Server

    Smalley, B; Pintado, O I; Gillon, M; Holdsworth, D L; Anderson, D R; Barros, S C C; Cameron, A Collier; Delrez, L; Faedi, F; Haswell, C A; Hellier, C; Horne, K; Jehin, E; Maxted, P F L; Norton, A J; Pollacco, D; Skillen, I; Smith, A M S; West, R G; Wheatley, P J

    2014-01-01

    The results of a search for eclipsing Am star binaries using photometry from the SuperWASP survey are presented. The light curves of 1742 Am stars fainter than V = 8.0 were analysed for the presences of eclipses. A total of 70 stars were found to exhibit eclipses, with 66 having sufficient observations to enable orbital periods to be determined and 28 of which are newly identified eclipsing systems. Also presented are spectroscopic orbits for 5 of the systems. The number of systems and the period distribution is found to be consistent with that identified in previous radial velocity surveys of `classical' Am stars.

  18. Binary system and jet precession and expansion in G35.20-0.74N

    Science.gov (United States)

    Beltrán, M. T.; Cesaroni, R.; Moscadelli, L.; Sánchez-Monge, Á.; Hirota, T.; Kumar, M. S. N.

    2016-09-01

    Context. Atacama Large Millimeter/submillimeter Array (ALMA) observations of the high-mass star-forming region G35.20-0.74N have revealed the presence of a Keplerian disk in core B rotating about a massive object of 18 M⊙, as computed from the velocity field. The luminosity of such a massive star would be comparable to (or higher than) the luminosity of the whole star-forming region. To solve this problem it has been proposed that core B could harbor a binary system. This could also explain the possible precession of the radio jet associated with this core, which has been suggested by its S-shaped morphology. Aims: We establish the origin of the free-free emission from core B and investigate the existence of a binary system at the center of this massive core and the possible precession of the radio jet. Methods: We carried out VLA continuum observations of G35.20-0.74N at 2 cm in the B configuration and at 1.3 cm and 7 mm in the A and B configurations. The bandwidth at 7 mm covers the CH3OH maser line at 44.069 GHz. Continuum images at 6 and 3.6 cm in the A configuration were obtained from the VLA archive. We also carried out VERA observations of the H2O maser line at 22.235 GHz. Results: The observations have revealed the presence of a binary system of UC/HC Hii regions at the geometrical center of the radio jet in G35.20-0.74N. This binary system, which is associated with a Keplerian rotating disk, consists of two B-type stars of 11 and 6 M⊙. The S-shaped morphology of the radio jet has been successfully explained as being due to precession produced by the binary system. The analysis of the precession of the radio jet has allowed us to better interpret the IR emission in the region, which would be not tracing a wide-angle cavity open by a single outflow with a position angle of ~55°, but two different flows: a precessing one in the NE-SW direction associated with the radio jet, and a second one in an almost E-W direction. Comparison of the radio jet images

  19. An optical & X-ray study of the counterpart to the SMC X-ray binary pulsar system SXP327

    CERN Document Server

    Coe, M J; Corbet, R H D; Galache, J; McBride, V A; Townsend, L J; Udalski, A

    2008-01-01

    Optical and X-ray observations are presented here of a newly reported X-ray transient system in the Small Magellanic Cloud. The data reveal many previously unknown X-ray detections of this system and clear evidence for a 49.995d binary period. In addition, the optical photometry show recurring outburst features at the binary period which may well be indicative of the neutron star interacting with a circumstellar disk around a Be star.

  20. Finishing Titanium Alloy Cutting Zone Analysis Via Multifunction Measuring System

    Science.gov (United States)

    Andrej, Czán; Michal, Šajgalík; Drbúl, Mário; Holubják, Jozef; Mrázik, Jozef; Babík, Ondrej; Zaušková, Lucia; Piešová, Marianna

    2015-12-01

    With the development of automotive, aerospace and biomedical industry, there is higher demand for exotic alloys, often based on titanium or nickel, though they are hard to machine. Therefore, it is essential to thoroughly understand their behavior during machining. Processes in the cutting zone of said materials are due to the complexity and dynamics defined by specific models. These include some deviations, thus it is essential to improve machining observation methodology, so exhibited errors and deviations are minimal or none. Based on the observations, multifunction measuring system has been designed, which allows simultaneous observation of characteristics such as e.g. cutting forces, deformations and thermal spread without uninterrupting machining process.