Phase Equilibria Relationships of High-Tc Superconductors

International Nuclear Information System (INIS)

Wong-Ng, Winnie

2011-01-01

As an integral part of a R and D program partially supported by the Electricity Delivery and Energy Reliability Office of DOE, we have determined phase equilibria data and phase diagrams for the three generations of superconductor materials: 1st generation, (Bi,Pb)-Sr-Ca- Cu-O systems; 2nd generation, Ba-R-Cu-O systems (R=lanthanides and yttrium); and 3rd generation, MgB2 systems. Our studies involved bulk materials, single crystals and thin films. This report gives a summary of our accomplishments, a list of publications, and 15 selected journal publications.

High-pressure phase equilibria in the (carbon dioxide + 1-hexanol) system

International Nuclear Information System (INIS)

Secuianu, Catinca; Feroiu, Viorel; Geana, Dan

2010-01-01

(Vapour + liquid) equilibria (VLE) and (vapour + liquid + liquid) equilibria (VLLE) data for the (carbon dioxide + 1-hexanol) system were measured at (293.15, 303.15, 313.15, 333.15, and 353.15) K. Phase behaviour measurements were made in a high-pressure visual cell with variable volume, based on the static-analytic method. The pressure range under investigation was between (0.6 and 14.49) MPa. The Soave-Redlich-Kwong (SRK) equation of state (EOS) with classical van der Waals mixing rules (two-parameters conventional mixing rule, 2PCMR), was used in a semi-predictive approach, in order to represent the complex phase behaviour (critical curve, LLV line, isothermal VLE, LLE, and VLLE) of the system. The topology of phase behaviour is reasonably well predicted.

Experimental study of the Cu-Al-Sn phase equilibria, close to the copper zone

Directory of Open Access Journals (Sweden)

Soares D.F.

2017-01-01

Full Text Available The ternary Cu-Al-Sn phase diagram is the base for several important types of alloys, with relevant industrial interest and applications. The knowledge of the melting/solidification alloys characteristics are determinant for their preparation and properties control. However, there is a lack of experimental information on the ternary phase diagram, at high temperature. In this work, several alloys, with high copper content and additions of Al, up to 10%, and Sn, up to 14% (in wt%, were studied by thermal analysis and by isothermal phase equilibria determination. The alloys liquidus and solidus lines and the binary α + β phase field, at 800°C, are presented for the studied range of compositions.

Gas hydrate phase equilibria measurement techniques and phase rule considerations

International Nuclear Information System (INIS)

Beltran, Juan G.; Bruusgaard, Hallvard; Servio, Phillip

2012-01-01

Highlights: → Inconsistencies found in hydrate literature. → Clarification to the number of variables needed to satisfy and justify equilibrium data. → Application of phase rule to mixed hydrate systems. → Thermodynamically consistent format to present data. - Abstract: A brief review of the Gibbs phase rule for non-reacting systems and its correct application to clathrate hydrates is presented. Clarification is provided for a common mistake found in hydrate phase-equilibria literature, whereby initial compositions are used as intensive variables to satisfy the Gibbs phase rule instead of the equilibrium values. The system of (methane + carbon dioxide + water) under (hydrate + liquid + vapor) equilibrium is used as a case study to illustrate key points and suggestions to improve experimental techniques are proposed.

Sn-In-Ag phase equilibria and Sn-In-(Ag)/Ag interfacial reactions

International Nuclear Information System (INIS)

Chen Sinnwen; Lee Wanyu; Hsu Chiaming; Yang Chingfeng; Hsu Hsinyun; Wu Hsinjay

2011-01-01

Research highlights: → Thermodynamic models of Sn-In and Sn-In-Ag are developed using the CALPHAD approach. → Reaction layer in the Sn-In-(Ag)/Ag couples at 100 deg. C is thinner than those at 25 deg. C, 50 deg. C, and 75 deg. C. → Reactions in the Sn-20 wt%In-2.8 wt%Ag/Ag couples are faster than those in the Sn-20 wt%In/Ag couples. - Abstract: Experimental verifications of the Sn-In and Sn-In-Ag phase equilibria have been conducted. The experimental measurements of phase equilibria and thermodynamic properties are used for thermodynamic modeling by the CALPHAD approach. The calculated results are in good agreement with experimental results. Interfacial reactions in the Sn-In-(Ag)/Ag couples have been examined. Both Ag 2 In and AgIn 2 phases are formed in the Sn-51.0 wt%In/Ag couples reacted at 100 and 150 deg. C, and only the Ag 2 In phase is formed when reacted at 25, 50 and 75 deg. C. Due to the different growth rates of different reaction phases, the reaction layer at 100 deg. C is thinner than those at 25 deg. C, 50 deg. C, and 75 deg. C. In the Sn-20.0 wt%In/Ag couples, the ζ phase is formed at 250 deg. C and ζ/AgIn 2 phases are formed at 125 deg. C. Compared with the Sn-20 wt%In/Ag couples, faster interfacial reactions are observed in the Sn-20.0 wt%In-2.8 wt%Ag/Ag couples, and minor Ag addition to Sn-20 wt%In solder increases the growth rates of the reaction phases.

Stability of equilibria for a two-phase osmosis model

NARCIS (Netherlands)

Lippoth, F.; Prokert, G.

2012-01-01

For a two-phase moving boundary problem modelling the motion of a semipermeable membrane by osmotic pressure and surface tension, we prove that the manifold of equilibria is locally exponentially attractive. Our method relies on maximal regularity results for parabolic systems with relaxation type

Electronic structure and phase equilibria in ternary substitutional alloys

International Nuclear Information System (INIS)

Traiber, A.J.S.; Allen, S.M.; Waterstrat, R.M.

1996-01-01

A reliable, consistent scheme to study phase equilibria in ternary substitutional alloys based on the tight-binding approximation is presented. With electronic parameters from linear muffin-tin orbital calculations, the computed density of states and band structures compare well with those from more accurate abinitio calculations. Disordered alloys are studied within the tight-binding coherent-potential approximation extended to alloys; energetics of ordered systems are obtained through effective pair interactions computed with the general perturbation method; and partially ordered alloys are studied with a novel simplification of the molecular coherent-potential approximation combined with the general perturbation method. The formalism is applied to bcc-based Zr-Ru-Pd alloys which are promising candidates for medical implant devices. Using energetics obtained from the above scheme, we apply the cluster- variation method to study phase equilibria for particular pseudo- binary alloys and show that results are consistent with observed behavior of electronic specific heat coefficient with composition for Zr 0.5 (Ru, Pd) 0.5

Influence of the temperature on the (liquid + liquid) phase equilibria of (water + 1-propanl + linalool or geraniol)

International Nuclear Information System (INIS)

Wan, Li; Li, Hengde; Huang, Cheng; Feng, Yuqing; Chu, Guoqiang; Zheng, Yuying; Tan, Wei; Qin, Yanlin; Sun, Dalei; Fang, Yanxiong

2017-01-01

Highlights: • Ternary LLEs containing linalool and geraniol are presented. • Distribution ratios of 1-propanol in the mixtures are examined. • Influence of the temperature on the LLE is studied. • The LLE data were correlated using the NRTL and UNIQUAC models. - Abstract: Linalool and geraniol are the primary components of rose oil, palmarosa oil, and citronella oil and many other essential oils, and two important compounds used in the flavour and fragrance, cosmetic or pharmaceutical industries. Phase equilibria (LLE, VLE, solubility, etc.) and related thermodynamic properties of a mixture are essential in the processes design and control of mass transfer process. In this work, experimental (liquid + liquid) equilibria data of the systems (water + 1-propanl + linalool) and (water + 1-propanl + geraniol) are presented. The (liquid + liquid) equilibria of both systems were determined with a tie-line method at T = (283.15, 298.15 and 313.15) K under atmospheric pressure. The well-known Hand, Bachman and Othmer–Tobias equations were used to test the reliability of the experimental values. The influence of the temperature on the (liquid + liquid) phase equilibria of the mixtures, the binodal curves and distribution ratios of 1-propanl are shown and discussed. Moreover, the NRTL and UNIQUAC models were applied to fit the data for both ternary systems. The interaction parameters obtained from both models successfully correlated the equilibrium compositions. Furthermore, the ternary systems could be represented using the binary parameters of the thermodynamic model with a function of temperature.

Phase equilibria in the BaUO3-BaZrO3-BaMoO3 system

International Nuclear Information System (INIS)

Kurosaki, Ken; Yamanaka, Shinsuke; Matsuda, Tetsushi; Uno, Masayoshi; Yamamoto, Kazuya; Namekawa, Takashi

2002-01-01

The phase equilibria in the pseudo-ternary BaUO 3 -BaZrO 3 -BaMoO 3 system were studied to understand the thermochemical properties of the perovskite type gray oxide phase in high burnup MOX fuel. Thermodynamic equilibrium calculation for the system was performed by using a Chem Sage program under the various oxygen potentials. Solid solutions existing in the system were treated by an ideal solution model. The present calculation results well agreed with the previous reported post irradiation examination results, showing that BaMoO 3 was scarcely included in the gray oxide phase. (author)

Development and testing of a new apparatus for the measurement of high-pressure low-temperature phase equilibria

DEFF Research Database (Denmark)

Fonseca, José M.S.; von Solms, Nicolas

2012-01-01

A new apparatus for the study of high-pressure phase equilibria at low temperatures using an analytical method was designed, assembled and tested. The apparatus was specially developed for the study of multi-phase equilibria in systems containing hydrocarbons, water and hydrate inhibitors, at tem...

Experimental investigation of phase equilibria in the Ni-Nb-V ternary system

Energy Technology Data Exchange (ETDEWEB)

Liu, Xingjun; Yang, Shuiyuan; Wang, Cuiping [Xiamen Univ. (China). Dept. of Materials Science and Engineering; Xiamen Univ. (China). Fujian Provincial Key Lab. of Materials Genome; Zhang, Xianjie; Jiang, Hengxing; Shi, Zhan [Xiamen Univ. (China). Dept. of Materials Science and Engineering

2017-09-15

The phase equilibria of the Ni-Nb-V ternary system at 1000 C and 1200 C were established using electron probe microanalysis, X-ray diffraction and differential scanning calorimetry. The results of the investigation revealed that: (1) The Nb solubility in (Ni) and σ{sup '} phases was less than 10 at.%; (2) A ternary compound τ (NiNbV) was confirmed, in which V had a large solubility; (3) A new liquid region was evident at 1200 C, but was absent at 1000 C; (4) The lattice constants of Ni{sub 3}Nb and Ni{sub 6}Nb{sub 7} phase decreased with increase in V content in the Ni{sub 3}Nb and Ni{sub 6}Nb{sub 7}. The phase equilibria of the Ni-Nb-V ternary system will contribute to its thermodynamic assessment.

Equation of state modeling of the phase equilibria of asymmetric CO2+n-alkane binary systems using mixing rules cubic with respect to mole fraction

DEFF Research Database (Denmark)

Cismondi, Martin; Mollerup, Jørgen M.; Zabaloy, Marcelo S.

2010-01-01

for a great diversity of mixtures. Nevertheless, the models for representing phase equilibria and physico-chemical properties of asymmetric systems may require more flexible mixing rules than the classical quadratic van der Waals (vdW) mixing rules or their equivalent (with regard to the number of available...... interaction parameters) in modern equations of state.In particular, the phase equilibria of binary mixtures containing CO2 and heavy n-alkanes have been studied by an important number of authors and using different types of models, achieving only partially accurate results and realizing the difficulties...

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

International Nuclear Information System (INIS)

Liu, Yajun; Wang, Guan; Wang, Jiang; Chen, Yang; Long, Zhaohui

2012-01-01

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.

Phase equilibria and thermodynamic functions for Ag-Hg and Cu-Hg binary systems

Energy Technology Data Exchange (ETDEWEB)

Liu, Yajun, E-mail: yajunliu@gatech.edu [School of Materials and Energy, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wang, Guan [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, Guangdong 510006 (China); Wang, Jiang [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Chen, Yang [Mining, Metallurgy and Materials Research Department, General Research Institute for Nonferrous Metals, Beijing 100088 (China); Long, Zhaohui [School of Mechanical Engineering, Xiangtan University, Xiangtan, Hunan 411105 (China)

2012-11-10

Highlights: Black-Right-Pointing-Pointer The thermodynamic properties of Ag-Hg and Cu-Hg are explored in order to facilitate dental materials design. Black-Right-Pointing-Pointer A self-consistent set of thermodynamic parameters is obtained. Black-Right-Pointing-Pointer 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.

Field line diversion properties of finite β Helias equilibria

International Nuclear Information System (INIS)

Hayashi, T.; Schwenn, U.; Strumberger, E.

1992-03-01

The diversion properties of the magnetic field outside the last closed magnetic surface of a Helias stellarator configuration are investigated for finite β-equilibria. The results support a divertor concept which has been developed from the diversion properties of the corresponding vacuum field. Cross-field transport is simulated by a simplified scrape-off layer (SOL) model. (author)

Phase equilibria, phases and compounds in the Ti-C system

International Nuclear Information System (INIS)

Gusev, Aleksandr I

2002-01-01

The results of experimental and theoretical investigations of the phase equilibria in the titanium-carbon system are generalised. The generalised thermodynamic characteristics of disordered titanium carbide TiC y , are reported. Peculiarities of the crystal structures of all the known and hypothetical compounds of titanium with carbon are considered in detail. The X-ray diffraction patterns which allow identification of all these compounds are presented. The phase diagrams of the Ti-C system constructed with allowance for atomic ordering of non-stoichio metric carbide, TiC y , and for the existence of the molecular cluster-like compounds Ti 8 C 12 and Ti 13 C 22 (TiC 2 ) are discussed. The bibliography includes 142 references.

Phase equilibria, phases and compounds in the Ti-C system

International Nuclear Information System (INIS)

Gusev, A.I.

2002-01-01

The results of experimental and theoretical investigations related to the phase equilibria in the titanium-carbon system are generalized. The generalized thermodynamic characteristics of the disordered titanium carbide TiC y are given. The crystal structure of all the discovered and hypothetical compounds of titanium with carbon are considered in detail. The x-ray diffraction patterns which allow one to identify all these compounds are given. The phase diagrams of the Ti-C system constructed with allowance for atomic ordering of non-stoichiometric TiC y carbide and for the existence of the compounds Ti 8 C 12 and Ti 13 C 22 (TiC 2 ) of the molecule cluster type are discussed [ru

Experimental investigation of phase equilibria in the Zr-Cu-Ni ternary system

International Nuclear Information System (INIS)

Yang, Mujin; Wang, Cuiping; Yang, Shuiyuan; Shi, Zhan; Han, Jiajia; Liu, Xingjun

2017-01-01

The phase equilibria in the Zr-Cu-Ni ternary system are investigated combined with X-ray diffraction, electron probe micro-analysis and differential scanning calorimetry. Two isothermal sections of the Zr-Cu-Ni ternary system at 1 000 C and 1 100 C are experimentally established. Most of the binary intermetallic compounds, e.g. Zr 7 Ni 10 , ZrNi, ZrNi 5 , Zr 14 Cu 51 , and Zr 2 Cu 9 , show a remarkable ternary solubility. A new ternary compound named τ 3 (Zr 31.1-30.7 . Cu 28.5-40.3 Ni 40.4-29.0 ) is detected at 1 000 C and dissolved at 1 020 C because the nearby large liquid phase field further expands. The newly determined phase equilibria will provide important information for both thermodynamic assessment and alloy design of Zr-based metallic glass.

Calculation of ethanol refining by means of extractive distillation with water using simulated data on phase equilibria

Energy Technology Data Exchange (ETDEWEB)

Rosak, J; Mertl, I; Huml, M; Wichterle, I

1980-01-01

Available data on phase equilibria in binary mixtures pertaining to the system ethanol - water - impurities (7 compounds that represent the main impurities present in raw synthetic or fermentation ethanol) have been gathered for the computer calculation of a column to be used for the refining of ethanol. Missing experimental data on phase equilibria were supplied by simulation using the increment method UNIFAC which predicts phase equilibria on the basis of the chemical structure. All data about the behavior of binary mixtures were correlated by means of the NRTL method and the sets of constants thus obtained were then used in calculations of the column for the refining of ethanol. The results were compared with reality verified on industrial scale.

Phase equilibria of didecyldimethylammonium nitrate ionic liquid with water and organic solvents

International Nuclear Information System (INIS)

Domanska, Urszula; Lugowska, Katarzyna; Pernak, Juliusz

2007-01-01

The phase diagrams for binary mixtures of an ammonium ionic liquid, didecyldimethylammonium nitrate, [DDA][NO 3 ], with: alcohols (propan-1-ol, butan-1-ol, octan-1-ol, and decan-1-ol): hydrocarbons (toluene, propylbenzene, hexane, and hexadecane) and with water were determined in our laboratory. The phase equilibria were measured by a dynamic method from T 220 K to either the melting point of the ionic liquid, or to the boiling point of the solvent. A simple liquidus curve in a eutectic system was observed for [DDA][NO 3 ] with: alcohols (propan-1-ol, butan-1-ol, and octan-1-ol); aromatic hydrocarbons (toluene and propylbenzene) and with water. (Solid + liquid) equilibria with immiscibility in the liquid phase were detected with the aliphatic hydrocarbons heptane and hexadecane and with decan-1-ol. (Liquid + liquid) equilibria for the system [DDA][NO 3 ] with hexadecane was observed for the whole mole fraction range of the ionic liquid. The observation of the upper critical solution temperature in binary mixtures of ([DDA][NO 3 ] + decan-1-ol, heptane, or hexadecane) was limited by the boiling temperature of the solvent. Characterisation and purity of the compounds were determined by elemental analysis, water content (Fisher method) and differential scanning microcalorimetry (d.s.c.) analysis. The d.s.c. method of analysis was used to determine melting temperatures and enthalpies of fusion. The thermal stability of the ionic liquid was resolved by the thermogravimetric technique-differential thermal analysis (TG-DTA) technique over a wide temperature range from (200 to 780) K. The thermal decomposition temperature of 50% of the sample was greater than 500 K. The (solid + liquid) phase equilibria, curves were correlated by means of different G Ex models utilizing parameters derived from the (solid + liquid) equilibrium. The root-mean-square deviations of the solubility temperatures for all calculated data are dependent upon the particular system and the particular

Experimental investigation of phase equilibria in the Zr-Cu-Ni ternary system

Energy Technology Data Exchange (ETDEWEB)

Yang, Mujin; Wang, Cuiping; Yang, Shuiyuan; Shi, Zhan; Han, Jiajia; Liu, Xingjun [Xiamen Univ. (China). College of Materials and Fujian Provincial Key Lab. of Materials Genome

2017-08-15

The phase equilibria in the Zr-Cu-Ni ternary system are investigated combined with X-ray diffraction, electron probe micro-analysis and differential scanning calorimetry. Two isothermal sections of the Zr-Cu-Ni ternary system at 1 000 C and 1 100 C are experimentally established. Most of the binary intermetallic compounds, e.g. Zr{sub 7}Ni{sub 10}, ZrNi, ZrNi{sub 5}, Zr{sub 14}Cu{sub 51}, and Zr{sub 2}Cu{sub 9}, show a remarkable ternary solubility. A new ternary compound named τ{sub 3} (Zr{sub 31.1-30.7} . Cu{sub 28.5-40.3}Ni{sub 40.4-29.0}) is detected at 1 000 C and dissolved at 1 020 C because the nearby large liquid phase field further expands. The newly determined phase equilibria will provide important information for both thermodynamic assessment and alloy design of Zr-based metallic glass.

Phase Equilibria Measurement of Binary Mixture for the Propoxylated Neopentyl Glycol Diacrylate in Supercritical Carbon Dioxide

International Nuclear Information System (INIS)

Byun, Hun-Soo

2016-01-01

Experimental data are reported on the phase equilibrium of propoxylated neopentyl glycol diacrylate in supercritical carbon dioxide. Phase equilibria data were measured in static method at a temperature of (313.2, 333.2, 353.2, 373.2 and 393.2) K and at pressures up to 27.82 MPa. At a constant pressure, the solubility of propoxylated neopentyl glycol diacrylate for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system increases as temperature increases. The (carbon dioxide + propoxylated neopentyl glycol diacrylate) system exhibits type-I phase behavior. The experimental result for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system is correlated with Peng- Robinson equation of state using mixing rule. The critical property of propoxylated neopentyl glycol diacrylate is predicted with Joback and Lyderson method

Phase Equilibria Measurement of Binary Mixture for the Propoxylated Neopentyl Glycol Diacrylate in Supercritical Carbon Dioxide

Energy Technology Data Exchange (ETDEWEB)

Byun, Hun-Soo [Chonnam National University, Yeosu (Korea, Republic of)

2016-04-15

Experimental data are reported on the phase equilibrium of propoxylated neopentyl glycol diacrylate in supercritical carbon dioxide. Phase equilibria data were measured in static method at a temperature of (313.2, 333.2, 353.2, 373.2 and 393.2) K and at pressures up to 27.82 MPa. At a constant pressure, the solubility of propoxylated neopentyl glycol diacrylate for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system increases as temperature increases. The (carbon dioxide + propoxylated neopentyl glycol diacrylate) system exhibits type-I phase behavior. The experimental result for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system is correlated with Peng- Robinson equation of state using mixing rule. The critical property of propoxylated neopentyl glycol diacrylate is predicted with Joback and Lyderson method.

Experimental investigation of phase equilibria in the Co-W-V ternary system

International Nuclear Information System (INIS)

Liu Xingjun; Zhu Yihong; Yu Yan; Wang Cuiping

2011-01-01

Highlights: → Three isothermal sections of the Co-W-V ternary system at 1100 deg. C, 1200 deg. C and 1300 deg. C were determined. → No ternary compound was found in the Co-W-V ternary system. → A stable liquid miscibility gap is newly discovered in the Co-W-V ternary system. → This work is of great essence to establish the thermodynamic database for the Co-based alloys. - Abstract: The phase equilibria in the Co-W-V ternary system were experimentally investigated by optical microscopy (OM), electron probe microanalysis (EPMA) and X-ray diffraction (XRD) on the equilibrated alloys. Three isothermal sections of the Co-W-V ternary system at 1100 deg. C, 1200 deg. C and 1300 deg. C were determined, and no ternary compound was found in this system. In addition, a novel phenomena induced by the liquid phase separation in the Co-W-V alloys was firstly discovered, suggesting that a stable liquid miscibility gap exists in the Co-W-V ternary system. The newly determined phase equilibria and firstly discovered phase separation phenomena in the Co-W-V system will provide important information for the development of Co-W based alloys.

Prediction of phase equilibria in the In–Sb–Pb system

Directory of Open Access Journals (Sweden)

DUSKO MINIC

2008-03-01

Full Text Available Binary thermodynamic data, successfully used for phase diagram calculations of the binary systems In–Sb, Pb–Sb and In–Pb, were used for the prediction of the phase equilibria in the ternary In–Sb–Pb system. The predicted equilibrium phase diagram of the vertical Pb–InSb section was compared with the results of differential thermal analysis DTA and optical microscopy. The calculated phase diagram of the isothermal section at 300 °C was compared with the experimentally (SEM, EDX determined composition of phases in the chosen alloys after annealing. Very good agreement between the binary-based thermodynamic prediction and the experimental data was found in all cases. The calculated liquidus projection of the ternary In–Sb–Pb system is also presented.

Another dimension to metamorphic phase equilibria: the power of interactive movies for understanding complex phase diagram sections

Science.gov (United States)

Moulas, E.; Caddick, M. J.; Tisato, N.; Burg, J.-P.

2012-04-01

The investigation of metamorphic phase equilibria, using software packages that perform thermodynamic calculations, involves a series of important assumptions whose validity can often be questioned but are difficult to test. For example, potential influences of deformation on phase relations, and modification of effective reactant composition (X) at successive stages of equilibrium may both introduce significant uncertainty into phase diagram calculations. This is generally difficult to model with currently available techniques, and is typically not well quantified. We present here a method to investigate such phenomena along pre-defined Pressure-Temperature (P-T) paths, calculating local equilibrium via Gibbs energy minimization. An automated strategy to investigate complex changes in the effective equilibration composition has been developed. This demonstrates the consequences of specified X modification and, more importantly, permits automated calculation of X changes that are likely along the requested path if considering several specified processes. Here we describe calculations considering two such processes and show an additional example of a metamorphic texture that is difficult to model with current techniques. Firstly, we explore the assumption that although water saturation and bulk-rock equilibrium are generally considered to be valid assumptions in the calculation of phase equilibria, the saturation of thermodynamic components ignores mechanical effects that the fluid/melt phase can impose on the rock, which in turn can modify the effective equilibrium composition. Secondly, we examine how mass fractionation caused by porphyroblast growth at low temperatures or progressive melt extraction at high temperatures successively modifies X out of the plane of the initial diagram, complicating the process of determining best-fit P-T paths for natural samples. In particular, retrograde processes are poorly modeled without careful consideration of prograde

Ternary equilibria in bismuth--indium--lead alloys

International Nuclear Information System (INIS)

Liao, K.C.; Johnson, D.L.; Nelson, R.C.

1975-01-01

The liquidus surface is characterized by three binary equilibria. One binary extends from the Pb--Bi peritectic to the Pb--In peritectic. The other two extend from In--Bi eutectics, merge at 50 at. percent Bi and 30 at. percent Pb, and end at the Bi--Pb eutectic. Based on analysis of ternary liquidus contours and vertical sections, it is suggested that solidification for high lead and very high indium alloys occurs from two-phase equilibria. Solidification from all other alloys occurs from three-phase equilibria. Four-phase solidification does not occur in this system

Description of gas hydrates equilibria in sediments using experimental data of soil water potential

Energy Technology Data Exchange (ETDEWEB)

Istomin, V. [NOVATEK, Moscow (Russian Federation); Chuvilin, E. [Moscow State Univ., Moscow (Russian Federation). Dept. of Geology; Makhonina, N.; Kvon, V. [VNIIGAZ, Moscow (Russian Federation); Safonov, S. [Schlumberger Moscow Research, Moscow (Russian Federation)

2008-07-01

Analytical relationships have been developed between hydrate dissociation pressure and vapor pressure above the pore water surface. In addition, experiments have been discussed in numerous publications on the effect of narrow interconnected throats between pores on clathrate dissociation conditions in porous media. This paper presented an approach that improved upon the available thermodynamic methods for calculation of hydrate phase equilibria. The approach took into account the properties of pore water in natural sediments including three-phase equilibrium of gas-pore water-gas hydrate in a similar way as for unfrozen water in geocryology science. The purpose of the paper was to apply and adapt geocryology and soil physics method to the thermodynamic calculation of non-clathrated water content in sediments. It answered the question of how to estimate the non-clathrated water content if pore water potential was known. The paper explained the thermodynamics of water phase in porous media including the thermodynamic properties of supercooled water, the thermodynamic properties of pore water and pore ice in sediments, and the phase equilibria of pore water. The paper also discussed the quantitative techniques that were utilized for determination of unfrozen water content in sediments and its dependence on temperature variation. These included contact-saturation, calorimetric, dielectric, nuclear magnetic resonance, and others. The thermodynamic calculations of pore water phase equilibria were also presented. 30 refs., 5 tabs., 8 figs.

Phase equilibria and stability of the B2 phase in the Ni-Mn-Al and Co-Mn-Al systems

International Nuclear Information System (INIS)

Kainuma, R.; Ise, M.; Ishikawa, K.; Ohnuma, I.; Ishida, K.

1998-01-01

The phase equilibria and ordering reactions in the composition region up to 50 at.% Al have been investigated in the Ni-Mn-Al and Co-Mn-Al systems at temperatures in the interval 850-1200 C mainly by the diffusion couple method. The compositions of the γ (A1: fcc-Ni, -Co, γ-Mn), γ' (L1 2 : Ni 3 Al), β (B2: NiAl, CoAl, NiMn), β-Mn (A13: β-Mn type), δ-Mn (A2: bcc-Mn) and ε (A3: hcp-(Mn, Al)) phases in equilibrium and the critical boundaries of the A2/B2 continuous ordering transition in the bcc phase region have been determined. It is shown that in the Mn-rich portion of the ternary systems both continuous and discontinuous A2 to B2 ordering transitions exist. The A2+B2 two-phase region in the isothermal sections has a lenticular shape and exists over a wide temperature range. The phase equilibria between the γ, γ', β, β-Mn, δ-Mn and ε phases are presented and the stability of the ordered bcc aluminides is discussed. (orig.)

Systematic identification method for data analysis and phase equilibria modelling for lipids systems

DEFF Research Database (Denmark)

Perederic, Olivia A.; Cunico, Larissa P.; Kalakul, Sawitree

2018-01-01

Industrial use of lipids has been increasing as a consequence of increased developments related to biobased economies. In addition to applications in food-products, lipids are used by many industrial sectors, for example, biodiesel, edible oil, health, and personal care. Phase equilibria...

Phase Equilibria of Sn-Co-Cu Ternary System

Science.gov (United States)

Chen, Yu-Kai; Hsu, Chia-Ming; Chen, Sinn-Wen; Chen, Chih-Ming; Huang, Yu-Chih

2012-10-01

Sn-Co-Cu ternary alloys are promising lead-free solders, and isothermal sections of Sn-Co-Cu phase equilibria are fundamentally important for the alloys' development and applications. Sn-Co-Cu ternary alloys were prepared and equilibrated at 523 K, 1073 K, and 1273 K (250 °C, 800 °C, and 1000 °C), and the equilibrium phases were experimentally determined. In addition to the terminal solid solutions and binary intermetallic compounds, a new ternary compound, Sn3Co2Cu8, was found. The solubilities of Cu in the α-CoSn3 and CoSn2 phases at 523 K (250 °C) are 4.2 and 1.6 at. pct, respectively, while the Cu solubility in the α-Co3Sn2 phase is as high as 20.0 at. pct. The Cu solubility increases with temperature and is around 30.0 at. pct in the β-Co3Sn2 at 1073 K (800 °C). The Co solubility in the η-Cu6Sn5 phase is also significant and is 15.5 at. pct at 523 K (250 °C).

Thermophysical properties and phase equilibria study of the binary systems {l_brace}N-hexylquinolinium bis(trifluoromethylsulfonyl)imide + aromatic hydrocarbons, or an alcohol{r_brace}

Energy Technology Data Exchange (ETDEWEB)

Domanska, Urszula, E-mail: ula@ch.pw.edu.p [Department of Physical Chemistry, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw (Poland); Thermodynamic Research Unit, School of Chemical Engineering, University of KwaZulu-Natal, Howard College Campus, King George V Avenue, Durban 4001 (South Africa); Zawadzki, Maciej [Department of Physical Chemistry, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw (Poland); Zwolinska, Magdalena [Department of Ergonomics, Laboratory of Thermal Loads, Central Institute for Labour Protection-National Research Institute, Czerniakowska 16, 00-701 Warsaw (Poland)

2011-05-15

Research highlights: We synthesized new ionic liquid, [HQuin][NTf{sub 2}] with low viscosity, and low density. We found high heat capacity, high enthalpy of melting and low melting temperature. HQuin][NTf{sub 2}] is proposed for possible use in the phase change materials (PCM). We examine phase equilibrium changes, SLE and LLE with hydrocarbons and alcohols. [HQuin][NTf{sub 2}] may be proposed as entrainer for the separation proceses. - Abstract: The new quinolinium ionic liquid has been synthesised as a continuation of our work with quinolinium-based ionic liquids (ILs). The work includes specific basic characterisation of synthesized compounds: N-hexylquinolinium bromide, [HQuin][Br] and N-hexylquinolinium bis{l_brace}(trifluoromethyl)sulfonyl{r_brace}imide [HQuin][NTf{sub 2}] by NMR spectra, elementary analysis and water content. The basic thermal properties of the pure [HQuin][NTf{sub 2}] i.e. melting and glass-transition temperatures, the enthalpy of fusion as well as heat capacity have been measured using a differential scanning microcalorimetry technique (DSC) and thermal analysis instrument (TA). Densities and viscosities were determined as a function of temperature. Phase equilibria for the binary systems: {l_brace}[HQuin][NTf{sub 2}]) + aromatic hydrocarbon (benzene, or toluene, or ethylbenzene, or n-propylbenzene), or an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol){r_brace} have been determined at ambient pressure. A dynamic method was used over a broad range of mole fractions and temperatures from (270 to 320) K. For all the binary systems with benzene and alkylbenzenes, the eutectic diagrams were observed with immiscibility gap in the liquid phase beginning from (0.13 to 0.28) mole fraction of the IL with very high an upper critical solution temperature (UCST). For mixtures with alcohols, the complete miscibility was observed for 1-butanol and immiscibility with UCST in the liquid phase for the remaining alcohols. The typical

Phase equilibria and molecular interaction studies on (naphthols + vanillin) systems

International Nuclear Information System (INIS)

Gupta, Preeti; Agrawal, Tanvi; Das, Shiva Saran; Singh, Nakshatra Bahadur

2012-01-01

Highlights: ► Phase equilibria of (naphthol + vanillin) systems have been studied for the first time. ► Eutectic type phase diagrams are obtained. ► Eutectic mixtures show nonideal behaviour. ► There is a weak molecular interaction between the components in the eutectic mixtures. ► α-Naphthol–vanillin eutectic is more stable as compared to β-naphthol–vanillin. - Abstract: Phase equilibria between (α-naphthol + vanillin) and (β-naphthol + vanillin) systems have been studied by thaw-melt method and the results show the formation of simple eutectic mixtures. Crystallization velocities of components and eutectic mixtures were determined at different stages under cooling. With the help of differential scanning calorimeter (DSC), the enthalpy of fusion of components and eutectic mixtures was determined and from the values excess thermodynamic functions viz., excess Gibbs free energy (G E ), excess entropy (S E ), excess enthalpy (H E ) of hypo-, hyper- and eutectic mixtures were calculated. Flexural strength measurements were made in order to understand the non-ideal nature of eutectics. FT-IR spectral studies indicate the formation of hydrogen bond in the eutectic mixture. Anisotropic and isotropic microstructural studies of components, hypo-, hyper- and eutectic mixtures were made. Jackson’s roughness parameter was calculated and found to be greater than 2 suggesting the faceted morphology with irregular structures. The overall results have shown that there is a weak molecular interaction between the components in the eutectic mixtures and the (α-naphthol + vanillin) eutectic is more stable as compared to the (β-naphthol + vanillin) eutectic system.

Metamorphism and partial melting of ordinary chondrites: Calculated phase equilibria

Science.gov (United States)

Johnson, T. E.; Benedix, G. K.; Bland, P. A.

2016-01-01

Constraining the metamorphic pressures (P) and temperatures (T) recorded by meteorites is key to understanding the size and thermal history of their asteroid parent bodies. New thermodynamic models calibrated to very low P for minerals and melt in terrestrial mantle peridotite permit quantitative investigation of high-T metamorphism in ordinary chondrites using phase equilibria modelling. Isochemical P-T phase diagrams based on the average composition of H, L and LL chondrite falls and contoured for the composition and abundance of olivine, ortho- and clinopyroxene, plagioclase and chromite provide a good match with values measured in so-called equilibrated (petrologic type 4-6) samples. Some compositional variables, in particular Al in orthopyroxene and Na in clinopyroxene, exhibit a strong pressure dependence when considered over a range of several kilobars, providing a means of recognising meteorites derived from the cores of asteroids with radii of several hundred kilometres, if such bodies existed at that time. At the low pressures (recorders of peak conditions. The intersection of isopleths of these variables may allow pressures to be quantified, even at low P, permitting constraints on the minimum size of parent asteroid bodies. The phase diagrams predict the onset of partial melting at 1050-1100 °C by incongruent reactions consuming plagioclase, clinopyroxene and orthopyroxene, whose compositions change abruptly as melting proceeds. These predictions match natural observations well and support the view that type 7 chondrites represent a suprasolidus continuation of the established petrologic types at the extremes of thermal metamorphism. The results suggest phase equilibria modelling has potential as a powerful quantitative tool in investigating, for example, progressive oxidation during metamorphism, the degree of melting and melt loss or accumulation required to produce the spectrum of differentiated meteorites, and whether the onion shell or rubble pile

Some stable hydromagnetic equilibria

Energy Technology Data Exchange (ETDEWEB)

Johnson, J L; Oberman, C R; Kulsrud, R M; Frieman, E A [Project Matterhorn, Princeton University, Princeton, NJ (United States)

1958-07-01

We have been able to find and investigate the properties of equilibria which are hydromagnetically stable. These equilibria can be obtained, for example, by wrapping conductors helically around the stellarator tube. Systems with I = 3 or 4 are indicated to be optimum for stability purposes. In some cases an admixture of I = 2 fields can be advantageous for achieving equilibrium. (author)

Phase equilibria of Al3(Ti,V,Zr) intermetallic system

International Nuclear Information System (INIS)

Park, S.I.; Han, S.Z.; Choi, S.K.; Lee, H.M.

1996-01-01

Trialuminides such as DO 22 -structured Al 3 Ti are promising candidates as potential materials for elevated temperature applications because of their attractive high temperature strength and excellent oxidation resistance along with their low density. However, in the tetragonal structure, slip systems are restricted due to low symmetry and the primary deformation mode is twinning. And, therefore, monolithic trialuminide compounds have been very impractical to be used as structural materials. When transition elements such as Ti, V and Zr which constitute trialuminides are alloyed in aluminum, they have low solubilities and low diffusion coefficients in the Al matrix. If precipitated as trialuminide intermetallics, they maintain a small lattice mismatch with the Al matrix, which reduces the interfacial energy between matrix and precipitates. As a result, these precipitates would have a large coarsening resistance in the matrix. As most of the previous works have been concentrated on the microstructural stability and mechanical properties, thermochemical properties will be treated in this work. In this study, phase equilibria and diagrams of Al 3 (Ti,V,Zr) systems will be experimentally determined and then thermodynamically analyzed with a hope to extend to the Al-Al 3 (Ti,V,Zr) composite system. This approach will then be used as a guide for alloy design of Al-Al 3 (Ti,V,Zr) composite system

Using a Differential Scanning Calorimeter to Teach Phase Equilibria to Students of Igneous and Metamorphic Petrology

Science.gov (United States)

Maria, Anton H.; Millam, Evan L.; Wright, Carrie L.

2011-01-01

As an aid for teaching phase equilibria to undergraduate students of igneous and metamorphic petrology, we have designed a laboratory exercise that allows them to create a phase diagram from data produced by differential scanning calorimetry. By preparing and analyzing samples of naphthalene and phenanthrene, students acquire hands-on insight into…

Solid-liquid phase equilibria of Fe-Cr-Al alloys and spinels

Science.gov (United States)

McMurray, J. W.; Hu, R.; Ushakov, S. V.; Shin, D.; Pint, B. A.; Terrani, K. A.; Navrotsky, A.

2017-08-01

Ferritic FeCrAl alloys are candidate accident tolerant cladding materials. There is a paucity of data concerning the melting behavior for FeCrAl and its oxides. Analysis tools have therefore had to utilize assumptions for simulations using FeCrAl cladding. The focus of this study is to examine in some detail the solid-liquid phase equilibria of FeCrAl alloys and spinels with the aim of improving the accuracy of severe accident scenario computational studies.

Experimental investigation of phase equilibria in the Nb-Si-Ta ternary system

Energy Technology Data Exchange (ETDEWEB)

Li, Jian; Wang, Cuiping; Yao, Jun; Yang, Shuiyuan; Zhan Shi; Liu, Xingjun [Xiamen Univ. (China). Dept. of Materials Science and Engineering; Xiamen Univ. (China). Fujian Provincial Key Laboratory of Materials Genome; Kang, Yongwang [Beijing Institute of Aeronautical Materials (China). Science and Technology on Advanced High Temperature Structural Materials Lab.

2016-12-15

The phase equilibria in the Nb-Si-Ta ternary system at 1 373 K, 1 473 K and 1 573 K were investigated by means of back-scattered electron imaging, electron probe microanalysis and X-ray diffraction. The isothermal sections at 1 373 K, 1 473 K and 1 573 K consist of two three-phase regions and seven two-phase regions, without any ternary compounds. The compounds of NbSi{sub 2} and TaSi{sub 2}, αNb{sub 5}Si{sub 3} and αTa{sub 5}Si{sub 3} form continuous solid solutions, respectively. The solubilities of Nb in Ta{sub 3}Si and Ta{sub 2}Si phases are extremely large, whereas the solubility of Si in the β(Nb, Ta) phase is relatively small.

The calculation of phase equilibria of oxide core-concrete systems

International Nuclear Information System (INIS)

Ball, R.G.J.; Mignanelli, M.A.; Barry, T.I.; Gisby, J.A.

1993-01-01

Thermodynamic models have been developed to describe the phase equilibria of oxide solutions appropriate for the understanding of the chemical interactions between nuclear reactor core debris and concrete. For this purpose, the Gibbs energy of the liquid phase is described by the inclusion of associate species and nonideal interactions between the components and associate species. Assessments of the thermodynamic and phase equilibrium data for the subsystems of the CaO-Al 2 O 3 -SiO 2 -UO 2 -ZrO 2 system have been used to obtain a thermodynamic description of the crystalline and liquid phases in good agreement with published data. The data for the subsystems have then been combined, using well established principles, to predict the phase relationships in the ternary and quaternary sytsems and in the overall quinary system. The results show that he overall system cannot properly be treated as a pseudo-ideal liquid and solid solution, as used in some computer codes which attempt to model the physics and chemistry of core-concrete interactions. The limitations of the current model are discussed. (orig.)

Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

Energy Technology Data Exchange (ETDEWEB)

Gabitto, Jorge; Barrufet, Maria

2002-11-20

The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibrium diagrams, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.

Thermal analysis and prediction of phase equilibria in ternary Pb-Zn-Ag system

Directory of Open Access Journals (Sweden)

Živković D.

2011-01-01

Full Text Available Ternary Pb-Zn-Ag system is typical for some physicochemical processes going on in refining phase in the extractive metallurgy of lead. Therefore, investigation of mentioned system is important from both theoretical and practical research of the phenomena occurring during the lead desilverizing process. The results of experimental investigation using differential thermal analysis (DTA and thermodynamic calculation of phase equilibria in Pb-Zn-Ag system according to CALPHAD method, in the sections with Zn:Ag mass ratio equal to 90:10, 70:30 and 50:50, are presented in this paper.

Phase equilibria in Dy-Cu-Al system at 500 deg C

International Nuclear Information System (INIS)

Kuz'ma, Yu.B.; Milyan, V.V.

1989-01-01

Using the methods of X-ray diffraction analysis a diagram of phase equilibria in Dy-Cu-Al system at 500 deg C is plotted. Boundaries of solid solutions on the basis of DyCu 2 , DyCu and DyAl 2 compounds are determined and homogeneity regions of ternary compounds Dy 2 (Cu, Al) 7 and Dy(CuAl) 5 are ascertained. Compounds DyCuAl 3 , Dy 4 Cu 4 Al 11 and Dy 5 Cu 6 Al 9 have been detected for the first time

Evaluation of ΔGsub(f) values for unstable compounds: a Fortran program for the calculation of ternary phase equilibria

International Nuclear Information System (INIS)

Throop, G.J.; Rogl, P.; Rudy, E.

1978-01-01

A Fortran IV program was set up for the calculation of phase equilibria and tieline distributions in ternary systems of the type: transition metal-transition metal-nonmetal (interstitial type of solid solutions). The method offers the possibility of determining the thermodynamic values for unstable compounds through their influence upon ternary phase equilibria. The variation of the free enthalpy of formation of ternary solid solutions is calculated as a function of nonmetal content, thus describing the actual curvature of the phase boundaries. The integral and partial molar free enthalpies of formation of binary nonstoichiometric compounds and of phase solutions are expressed as analytical functions of the nonmetal content within their homogeneity range. The coefficient of these analytical expressions are obtained by the use either of the Wagner-Schottky vacancy model or polynomials second order in composition (parabolic approach). The free energy of formation, ΔGsub(f) has been calculated for the systems Ti-C, Zr-C, and Ta-C. Calculations of the ternary phase equilibria yielded the values for ΔGsub(f) for the unstable compounds Ti 2 C at 1500 0 C and Zr 2 C at 1775 0 C of -22.3 and 22.7 kcal g atom metal respectively. These values were used for the calculation of isothermal sections within the ternary systems Ti-Ta-C (at 1500 0 C) and Zr-Ta-C (at 1775 0 C). The ideal case of ternary phase solutions is extended to regular solutions. (author)

Phase equilibria in the MgMoO4-Ln2(MoO4)3 (Ln=La,Gd) systems

International Nuclear Information System (INIS)

Fedorov, N.F.; Ipatov, V.V.; Kvyatkovskij, O.V.

1980-01-01

Phase equilibria in the MgMoO 4 -Ln 2 (MoO 4 ) 3 systems (Ln=La, Gd) have been studied by static and dynamic methods of the physico-chemical analysis, using differential thermal, visual-polythermal, crystal-optical, X-ray phase, and infrared spectroscopic methods, and their phase diagrams have been constructed. Phase equilibria in the systems studied are characterized by limited solubility of components in the liquid state, formation of solid solutions on the base of α- and β-forms of Gd 2 (MoO 4 ) 3 . Eutectics in the MgMoO 4 -Ln 2 (MoO 4 ) 3 (Ln=La, Gd) systems corresponds to the composition of 71 mode % La 2 (MoO 4 ) 3 -29 mole % MgMoO 4 , tsub(melt)--935+-5 deg C and 57 mole % Gd 2 (MoO 4 ) 3 -43 mole % MgMoO 4 , tsub(melt)=1020+-5 deg C. The region of glass formation has been established [ru

Phase equilibria and crystalline structure of compounds in the Lu-Al and Lu-Cu-Al systems

International Nuclear Information System (INIS)

Kuz'ma, Yu.B.; Stel'makhovich, B.M.; Galamushka, L.I.

1992-01-01

Phase equilibria and crystal structure of compounds in Lu-Al and Lu-Cu-Al systems were studied. Existence of Lu 2 Al compound having the structure of the PbCl 2 type is ascertained. Diagram of phase equilibria of Lu-Cu-Al system at 870 K is plotted. Compounds Lu 2 (Cu,Al) 17 (the Th 2 Zn 17 type structure), Lu(Cu,Al) 5 (CaCu 5 type structure), Lu 6 (Cu,Al) 23 (Th 6 Mn 23 type structure) and ∼ LuCuAl 2 have been prepared for the first time. Investigation of component interaction in Lu-Cu-Al system shows that the system is similar to previously studied systems Dy-Cu-Al and Er-Cu-Al. The main difference consists in the absence of LuCuAl 3 compound with rhombic structure of the CeNi 2+x Sb 2-x type in the system investigated

Phase equilibria constraints on the chemical and physical evolution of the campanian ignimbrite

Science.gov (United States)

Fowler, S.J.; Spera, F.J.; Bohrson, W.A.; Belkin, H.E.; de Vivo, B.

2007-01-01

The Campanian Ignimbrite is a > 200 km3 trachyte-phonolite pyroclastic deposit that erupted at 39.3 ?? 0.1 ka within the Campi Flegrei west of Naples, Italy. Here we test the hypothesis that Campanian Ignimbrite magma was derived by isobaric crystal fractionation of a parental basaltic trachyandesitic melt that reacted and came into local equilibrium with small amounts (5-10 wt%) of crustal rock (skarns and foid-syenites) during crystallization. Comparison of observed crystal and magma compositions with results of phase equilibria assimilation-fractionation simulations (MELTS) is generally very good. Oxygen fugacity was approximately buffered along QFM+1 (where QFM is the quartz-fayalite-magnetite buffer) during isobaric fractionation at 0.15 GPa (???6 km depth). The parental melt, reconstructed from melt inclusion and host clinopyroxene compositions, is found to be basaltic trachyandesite liquid (51.1 wt% SiO2, 9.3 wt% MgO, 3 wt% H2O). A significant feature of phase equilibria simulations is the existence of a pseudo-invariant temperature, ???883??C, at which the fraction of melt remaining in the system decreases abruptly from ???0.5 to point leads to abrupt changes in the composition, properties (density, dissolved water content), and physical state (viscosity, volume fraction fluid) of melt and magma. A dramatic decrease in melt viscosity (from 1700 Pa s to ???200 Pa s), coupled with a change in the volume fraction of water in magma (from ??? 0.1 to 0.8) and a dramatic decrease in melt and magma density acted as a destabilizing eruption trigger. Thermal models suggest a timescale of ??? 200 kyr from the beginning of fractionation until eruption, leading to an apparent rate of evolved magma generation of about 10-3 km3/year. In situ crystallization and crystal settling in density-stratified regions, as well as in convectively mixed, less evolved subjacent magma, operate rapidly enough to match this apparent volumetric rate of evolved magma production

Phase equilibria and critical phenomena in the cesium nitrate-water-diethylamine ternary system

International Nuclear Information System (INIS)

Il'in, K.K.; Kurskij, V.F.; Cherkasov, D.G.

2008-01-01

Phase equilibria and critical events in ternary cesium nitrate-water-diethylamine system, where border binary liquid system is characterized by aliquation with lower critical temperature of solution (LCTS), have been investigated by visual-polythermal method in the 60-150 Deg C range. Interaction of cesium nitrate in the water-diethylamine system leads to lowering of its LCTS from 146.1 to 69.3 Deg C and decrease of mutual solubility. Distribution ratios of diethylamine between water and organic phases of monotectic equilibrium are calculated at different temperatures. Diethylamine salting out from aqueous solutions by cesium nitrates becomes stronger with rising temperature. Plotted isotherms of phase confirms generalized scheme of topological transformations of ternary systems phase diagrams: salt-binary solvent with salting out

Phase equilibria of carbohydrates in polar solvents

DEFF Research Database (Denmark)

Jonsdottir, Svava Osk; Rasmussen, Peter

1999-01-01

A method for calculating interaction energies and interaction parameters with molecular mechanics methods is extended to predict solid-liquid equilibria (SLE) for saccharides in aqueous solution, giving results in excellent agreement with experimental values. Previously, the method has been shown...

Phase equilibria of the Al-Pr-Zr ternary system at 773 K

International Nuclear Information System (INIS)

She, Jia; Zhan, Yongzhong; Li, Chunliu; Du, Yong; Xu, Honghui; He, Yuehui

2010-01-01

The phase equilibria of the Al-Pr-Zr ternary system at 773 K have been investigated mainly by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA). The 14 binary compounds, i.e. AlZr 3 , AlZr 2 , Al 2 Zr 3 , Al 3 Zr 4 , AlZr, Al 3 Zr 2 , Al 2 Zr, Al 3 Zr, α-Al 11 Pr 3 , Al 3 Pr, Al 2 Pr, β-AlPr, AlPr 2 and β-AlPr 3 were confirmed. No binary compound was found in the Pr-Zr binary system. The result shows that the isothermal section of the Al-Pr-Zr ternary system at 773 K consists of 17 single-phase regions, 31 two-phase regions and 15 three-phase regions. All the intermediate compounds phases in this system have not a remarkable solid solution at 773 K. No ternary compound is found in this work.

An energy stable evolution method for simulating two-phase equilibria of multi-component fluids at constant moles, volume and temperature

KAUST Repository

Kou, Jisheng; Sun, Shuyu; Wang, Xiuhua

2016-01-01

In this paper, we propose an energy-stable evolution method for the calculation of the phase equilibria under given volume, temperature, and moles (VT-flash). An evolution model for describing the dynamics of two-phase fluid system is based on Fick

Phase equilibria, crystal structure and oxygen content of intermediate phases in the Y-Ba-Co-O system

OpenAIRE

Urusova, A. S.; Cherepanov, V. A.; Aksenova, T. V.; Gavrilova, L. Y.; Kiselev, E. A.

2013-01-01

The phase equilibria in the Y-Ba-Co-O system were systematically studied at 1373 K in air. The intermediate phases formed in the Y-Ba-Co-O system at 1373 K in air were: YBaCo2O5+δ, YBaCo4O 7 and BaCo1-yYyO3-δ (0.09≤y≤0.42). It was shown that YBaCo2O5+δ possesses tetragonal structure with the 3ap×3a p×2ap superstructure (sp. gr. P4/mmm). High-temperature X-ray diffraction analysis of the YBaCo2O 5+δ in the temperature range from 298 K up to 1073 K under Po2=0.21 atm has not shown any phase tra...

Evaluation of Thermodynamic Models for Predicting Phase Equilibria of CO2 + Impurity Binary Mixture

Science.gov (United States)

Shin, Byeong Soo; Rho, Won Gu; You, Seong-Sik; Kang, Jeong Won; Lee, Chul Soo

2018-03-01

For the design and operation of CO2 capture and storage (CCS) processes, equation of state (EoS) models are used for phase equilibrium calculations. Reliability of an EoS model plays a crucial role, and many variations of EoS models have been reported and continue to be published. The prediction of phase equilibria for CO2 mixtures containing SO2, N2, NO, H2, O2, CH4, H2S, Ar, and H2O is important for CO2 transportation because the captured gas normally contains small amounts of impurities even though it is purified in advance. For the design of pipelines in deep sea or arctic conditions, flow assurance and safety are considered priority issues, and highly reliable calculations are required. In this work, predictive Soave-Redlich-Kwong, cubic plus association, Groupe Européen de Recherches Gazières (GERG-2008), perturbed-chain statistical associating fluid theory, and non-random lattice fluids hydrogen bond EoS models were compared regarding performance in calculating phase equilibria of CO2-impurity binary mixtures and with the collected literature data. No single EoS could cover the entire range of systems considered in this study. Weaknesses and strong points of each EoS model were analyzed, and recommendations are given as guidelines for safe design and operation of CCS processes.

Phase Equilibria and Compressibility of bastnaesite-(La)

Science.gov (United States)

Rowland, R. L., II; Burnley, P. C.

2015-12-01

Bastnaesite (Ce,La,Y)CO3(F,OH) is a rare earth element (REE) bearing ore mineral. REEs are more common in the Earth's crust than precious metals like gold or platinum, but are not commonly concentrated in economically viable ore deposits. For over a decade, China has been the world's leading supplier of REEs. Recent export restrictions from China have necessitated the search for new deposits. Determining basic material properties such as phase equilibria and the equation of state for bastnaesite helps in understanding the processes that form REE ore deposits and thereby assist in locating new deposits. For this study we focus on the lanthanum-fluoride variant of bastnaesite (LaCO3F) since it can be easily synthesized in the laboratory. Previous work by others determined that in both open and closed systems at atmospheric pressure bastnaesite decomposes to lanthanum oxyfluoride and carbon dioxide (LaOF + CO2) above 325°C; at 100 MPa bastnaesite decomposes above 860°C (Hsu, 1992). Using a Griggs-type modified piston cylinder apparatus, we pressurized samples of synthetic bastnaesite-(La) to conditions ranging from 250 MPa to 1.2 GPa, and then subjected each sample to constant temperatures ranging from 700°C to 1050°C for a minimum of five hours. We then analyzed the samples with X-ray powder diffraction to identify phases present and determined that bastnaesite-(La) is stable at 250 MPa up to approximately 800°C and at 1.0 GPa up to approximately 900°C. Reversal experiments are underway. In order to develop an equation of state for bastnaesite-(La), we studied single crystals via monochromatic synchrotron X-ray diffraction in the diamond anvil cell at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. Measurements were made at pressures ranging from ambient to nearly 4 GPa. From these diffraction patterns, we determine the structure of bastnaesite-(La), and the change in unit cell volume as a function of pressure can be fit to a Birch

Insight into the Am-O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling.

Science.gov (United States)

Epifano, Enrica; Guéneau, Christine; Belin, Renaud C; Vauchy, Romain; Lebreton, Florent; Richaud, Jean-Christophe; Joly, Alexis; Valot, Christophe; Martin, Philippe M

2017-07-03

In the frame of minor actinide transmutation, americium can be diluted in UO 2 and (U, Pu)O 2 fuels burned in fast neutron reactors. The first mandatory step to foresee the influence of Am on the in-reactor behavior of transmutation targets or fuel is to have fundamental knowledge of the Am-O binary system and, in particular, of the AmO 2-x phase. In this study, we coupled HT-XRD (high-temperature X-ray diffraction) experiments with CALPHAD thermodynamic modeling to provide new insights into the structural properties and phase equilibria in the AmO 2-x -AmO 1.61+x -Am 2 O 3 domain. Because of this approach, we were able for the first time to assess the relationships between temperature, lattice parameter, and hypostoichiometry for fcc AmO 2-x . We showed the presence of a hyperstoichiometric existence domain for the bcc AmO 1.61+x phase and the absence of a miscibility gap in the fcc AmO 2-x phase, contrary to previous representations of the phase diagram. Finally, with the new experimental data, a new CALPHAD thermodynamic model of the Am-O system was developed, and an improved version of the phase diagram is presented.

Pierce instability and bifurcating equilibria

International Nuclear Information System (INIS)

Godfrey, B.B.

1981-01-01

The report investigates the connection between equilibrium bifurcations and occurrence of the Pierce instability. Electrons flowing from one ground plane to a second through an ion background possess a countable infinity of static equilibria, of which only one is uniform and force-free. Degeneracy of the uniform and simplest non-uniform equilibria at a certain ground plan separation marks the onset of the Pierce instability, based on a newly derived dispersion relation appropriate to all the equilibria. For large ground plane separations the uniform equilibrium is unstable and the non-uniform equilibrium is stable, the reverse of their stability properties at small separations. Onset of the Pierce instability at the first bifurcation of equilibria persists in more complicated geometries, providing a general criterion for marginal stability. It seems probable that bifurcation analysis can be a useful tool in the overall study of stable beam generation in diodes and transport in finite cavities

On Equilibria of the Two-fluid Model in Magnetohydrodynamics

International Nuclear Information System (INIS)

Frantzeskakis, Dimitri J.; Stratis, Ioannis G.; Yannacopoulos, Athanasios N.

2004-01-01

We show how the equilibria of the two-fluid model in magnetohydrodynamics can be described by the double curl equation and through the study of this equation we study some properties of these equilibria

Experimental investigation of phase equilibria in the Co-Ni-Zr ternary system

Energy Technology Data Exchange (ETDEWEB)

Liu, Xingjun; Yang, Shuiyuan; Yu, Wenjie; Wang, Cuiping [Xiamen Univ. (China). Fujian Key Laboratory of Materials Genome; Xiong, Huaping; Cheng, Yaoyong; Wu, Xin [Beijing Institute of Aeronautical Materials (China). Div. of Welding and Forging

2016-10-15

The phase equilibria of the Co-Ni-Zr ternary system at 1 000 C, 1 100 C and 1 200 C were experimentally investigated by means of back-scattered electron imaging, electron probe microanalysis and X-ray diffraction on the equilibrated ternary alloys. In this study, no ternary compound is found. The (αCo, Ni) phase region extends from the Ni-rich corner to the Co-rich corner with small solubility of Zr at three sections. At 1 000 C and 1 100 C, Ni{sub 5}Zr, Co{sub 2}Zr and Ni{sub 10}Zr{sub 7} phases have large solid solution ranges, but Ni{sub 10}Zr{sub 7} phase disappears at 1 200 C. The Ni{sub 7}Zr{sub 2}, NiZr, Co{sub 11}Zr{sub 2}, Co{sub 23}Zr{sub 6} and CoZr phases exhibit nearly linear compounds in the studied sections, and have large composition ranges. Additionally, some differences in phase relationship exist among the above three isothermal sections.

Experimental investigation of phase equilibria in the Cu–Ni–Si ternary system

Energy Technology Data Exchange (ETDEWEB)

Liu, Xingjun; Xiang, Shulin; Yang, Shuiyuan; Shi, Rongpei; Wang, Cuiping, E-mail: wangcp@xmu.edu.cn

2013-11-25

Highlights: •Three isothermal sections of the Cu–Ni–Si system have been investigated. •The ternary compound τ{sub 1} and the liquid phase are confirmed at 1073 K. •The γ (Cu{sub 5}Si) and θ (Ni{sub 2}Si) phases can be stabilized at higher or lower temperatures. -- Abstract: The phase equilibria in the Cu–Ni–Si ternary system have been investigated experimentally by means of electron probe microanalysis (EPMA), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis on equilibrated ternary alloys. Three isothermal sections at 1073, 1173 and 1273 K are determined in the whole composition range. The existence of liquid phase and the ternary compound τ{sub 1} is confirmed at 1073 K. The binary γ (Cu{sub 5}Si), γ (Ni{sub 31}Si{sub 12}), δ (Ni{sub 2}Si) and θ (Ni{sub 2}Si) phases exhibit a considerable solubility of a third element. In addition, the γ (Cu{sub 5}Si) and θ (Ni{sub 2}Si) phases can be stabilized by the addition of Ni and Cu, respectively.

Phase equilibria modeling of methanol-containing systems with the CPA and sPC-SAFT equations of state

DEFF Research Database (Denmark)

Tybjerg, Peter Chr. V.; Kontogeorgis, Georgios; Michelsen, Michael Locht

2010-01-01

Proper representation at various conditions of phase equilibria of methanol-containing mixtures (with hydrocarbons, water, etc.) is Important for oil flow assurance purposes In this work two association equations of state. CPA and sPC-SAFT, are applied to methanol-containing mixtures The purpose ...

Effect of temperature on acid-base equilibria in separation techniques. A review.

Science.gov (United States)

Gagliardi, Leonardo G; Tascon, Marcos; Castells, Cecilia B

2015-08-19

Studies on the theoretical principles of acid-base equilibria are reviewed and the influence of temperature on secondary chemical equilibria within the context of separation techniques, in water and also in aqueous-organic solvent mixtures, is discussed. In order to define the relationships between the retention in liquid chromatography or the migration velocity in capillary electrophoresis and temperature, the main properties of acid-base equilibria have to be taken into account for both, the analytes and the conjugate pairs chosen to control the solution pH. The focus of this review is based on liquid-liquid extraction (LLE), liquid chromatography (LC) and capillary electrophoresis (CE), with emphasis on the use of temperature as a useful variable to modify selectivity on a predictable basis. Simplified models were evaluated to achieve practical optimizations involving pH and temperature (in LLE and CE) as well as solvent composition in reversed-phase LC. Copyright © 2015 Elsevier B.V. All rights reserved.

Prediction of phase equilibria and thermal analysis in the Bi-Cu-Pb ternary system

Energy Technology Data Exchange (ETDEWEB)

Manasijevic, Dragan [University of Belgrade, Technical Faculty, VJ 12, 19210 Bor (Serbia); Mitovski, Aleksandra, E-mail: amitovski@tf.bor.ac.rs [University of Belgrade, Technical Faculty, VJ 12, 19210 Bor (Serbia); Minic, Dusko [University of Pristina, Faculty of Technical Sciences, 38220 Kosovska Mitrovica (Serbia); Zivkovic, Dragana; Marjanovic, Sasa [University of Belgrade, Technical Faculty, VJ 12, 19210 Bor (Serbia); Todorovic, Radisa [Institute of Mining and Metallurgy, Zeleni Bulevar 35, 19210 Bor (Serbia); Balanovic, Ljubisa [University of Belgrade, Technical Faculty, VJ 12, 19210 Bor (Serbia)

2010-05-20

The knowledge about phase diagram of the Bi-Cu-Pb ternary system is of importance in development of copper-lead based bearing materials, soldering and in refining of copper and lead. In this work, the phase diagram of the Bi-Cu-Pb ternary system was calculated by the CALPHAD method using binary thermodynamic parameters included in the COST 531 database. The results include liquidus projection, invariant equilibria and three vertical sections with molar ratio Cu:Pb = 1, Cu:Pb = 1:3 and Bi:Cu = 1. Alloys, with compositions along three predicted vertical sections, were measured using differential scanning calorimetry (DSC). The experimentally determined phase transition temperatures were compared with calculated results and good mutual agreement was noticed.

Prediction of phase equilibria and thermal analysis in the Bi-Cu-Pb ternary system

International Nuclear Information System (INIS)

Manasijevic, Dragan; Mitovski, Aleksandra; Minic, Dusko; Zivkovic, Dragana; Marjanovic, Sasa; Todorovic, Radisa; Balanovic, Ljubisa

2010-01-01

The knowledge about phase diagram of the Bi-Cu-Pb ternary system is of importance in development of copper-lead based bearing materials, soldering and in refining of copper and lead. In this work, the phase diagram of the Bi-Cu-Pb ternary system was calculated by the CALPHAD method using binary thermodynamic parameters included in the COST 531 database. The results include liquidus projection, invariant equilibria and three vertical sections with molar ratio Cu:Pb = 1, Cu:Pb = 1:3 and Bi:Cu = 1. Alloys, with compositions along three predicted vertical sections, were measured using differential scanning calorimetry (DSC). The experimentally determined phase transition temperatures were compared with calculated results and good mutual agreement was noticed.

Phase equilibria and thermodynamic modeling of ethane and propane hydrates in porous silica gels.

Science.gov (United States)

Seo, Yongwon; Lee, Seungmin; Cha, Inuk; Lee, Ju Dong; Lee, Huen

2009-04-23

In the present study, we examined the active role of porous silica gels when used as natural gas storage and transportation media. We adopted the dispersed water in silica gel pores to substantially enhance active surface for contacting and encaging gas molecules. We measured the three-phase hydrate (H)-water-rich liquid (L(W))-vapor (V) equilibria of C(2)H(6) and C(3)H(8) hydrates in 6.0, 15.0, 30.0, and 100.0 nm silica gel pores to investigate the effect of geometrical constraints on gas hydrate phase equilibria. At specified temperatures, the hydrate stability region is shifted to a higher pressure region depending on pore size when compared with those of bulk hydrates. Through application of the Gibbs-Thomson relationship to the experimental data, we determined the values for the C(2)H(6) hydrate-water and C(3)H(8) hydrate-water interfacial tensions to be 39 +/- 2 and 45 +/- 1 mJ/m(2), respectively. By using these values, the calculation values were in good agreement with the experimental ones. The overall results given in this study could also be quite useful in various fields, such as exploitation of natural gas hydrate in marine sediments and sequestration of carbon dioxide into the deep ocean.

Phase equilibria of the Al-Pr-Zr ternary system at 773 K

Energy Technology Data Exchange (ETDEWEB)

She, Jia [Laboratory of Nonferrous Metal Materials and New Processing Technology, Ministry of Education, Guangxi University, Nanning, Guangxi 530004 (China); Zhan, Yongzhong, E-mail: zyzmatres@yahoo.com.c [Laboratory of Nonferrous Metal Materials and New Processing Technology, Ministry of Education, Guangxi University, Nanning, Guangxi 530004 (China); Li, Chunliu [Laboratory of Nonferrous Metal Materials and New Processing Technology, Ministry of Education, Guangxi University, Nanning, Guangxi 530004 (China); Du, Yong; Xu, Honghui; He, Yuehui [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

2010-07-30

The phase equilibria of the Al-Pr-Zr ternary system at 773 K have been investigated mainly by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA). The 14 binary compounds, i.e. AlZr{sub 3}, AlZr{sub 2}, Al{sub 2}Zr{sub 3}, Al{sub 3}Zr{sub 4}, AlZr, Al{sub 3}Zr{sub 2}, Al{sub 2}Zr, Al{sub 3}Zr, {alpha}-Al{sub 11}Pr{sub 3}, Al{sub 3}Pr, Al{sub 2}Pr, {beta}-AlPr, AlPr{sub 2} and {beta}-AlPr{sub 3} were confirmed. No binary compound was found in the Pr-Zr binary system. The result shows that the isothermal section of the Al-Pr-Zr ternary system at 773 K consists of 17 single-phase regions, 31 two-phase regions and 15 three-phase regions. All the intermediate compounds phases in this system have not a remarkable solid solution at 773 K. No ternary compound is found in this work.

Experimental investigation of the phase equilibria in the Co-Fe-Ti ternary system

Energy Technology Data Exchange (ETDEWEB)

Yuan, Chaohui; Chen, Chong; Peng, Yingbiao; Du, Yong; Li, Kun [Central South Univ., State Key of Powder Metallurgy, Changsha (China); Lu, Xingxu [Central South Univ., State Key of Powder Metallurgy, Changsha (China); Central South Univ., School of Materials Science and Engineering, Changsha (China)

2015-08-15

Phase equilibria in the Co-Fe-Ti ternary system were investigated by means of the equilibrated alloy method with X-ray powder diffraction and electron probe microanalysis. No ternary compounds were found. The experimental results indicated the existence of seven two-phase and one three-phase regions at 600 C, five two-phase and two three-phase regions at 800 C, and six two-phase and two three-phase regions at 950 C. The solubility of Co in TiFe{sub 2} was determined to be larger than 54 at.% at all investigated temperatures, and the solubilities of Fe in TiCo{sub 3} and Ti{sub 2}Co showed an appreciable increase with increasing temperature. The three-phase equilibrium in the Ti-rich corner at 800 C was revealed to be ((β-Ti) + Ti(Fe, Co) + Ti{sub 2}Co) rather than ((α-Ti) + Ti(Fe, Co) + Ti{sub 2}Co) reported in previous investigations. Based on the experimental data obtained in the present work, three isothermal sections at 600, 800 and 950 C were established.

Phase equilibria in TlX-Cd(Zn)X (X-S, Se, Te) systems

International Nuclear Information System (INIS)

Gusejnov, F.Kh.; Babanly, M.B.; Kuliev, A.A.

1982-01-01

The methods of DTA, RPA and measurement of the alloys microhardness have been used to investigate the phase equilibria in the TlX-Zn(Cd)X systems. It is established that the TlZn(Cd)X 2 compounds, the presence of which is mentioned in the literature earlier, do not form in these systems. The TlSe-Zn(Cd)Se systems apply to the simple eutectic type and characterized by digenerated eutectic near the TlSe. Thermodynamical analysis of the liquidus of the TlSe-CdSe and TlTe-Zn(Cd)Te systems in approximation of the regular solutions, taking into account the dissociation of tallium chalcogenides in liquid phase, is made

Phase Equilibria of the Sn-Ni-Si Ternary System and Interfacial Reactions in Sn-(Cu)/Ni-Si Couples

Science.gov (United States)

Fang, Gu; Chen, Chih-chi

2015-07-01

Interfacial reactions in Sn/Ni-4.5 wt.%Si and Sn-Cu/Ni-4.5 wt.%Si couples at 250°C, and Sn-Ni-Si ternary phase equilibria at 250°C were investigated in this study. Ni-Si alloys, which are nonmagnetic, can be regarded as a diffusion barrier layer material in flip chip packaging. Solder/Ni-4.5 wt.%Si interfacial reactions are crucial to the reliability of soldered joints. Phase equilibria information is essential for development of solder/Ni-Si materials. No ternary compound is present in the Sn-Ni-Si ternary system at 250°C. Extended solubility of Si in the phases Ni3Sn2 and Ni3Sn is 3.8 and 6.1 at.%, respectively. As more Si dissolves in these phases their lattice constants decrease. No noticeable ternary solubility is observed for the other intermetallics. Interfacial reactions in solder/Ni-4.5 wt.%Si are similar to those for solder/Ni. Si does not alter the reaction phases. No Si solubility in the reaction phases was detected, although rates of growth of the reaction phases were reduced. Because the alloy Ni-4.5 wt.%Si reacts more slowly with solders than pure Ni, the Ni-4.5 wt.%Si alloy could be a potential new diffusion barrier layer material for flip chip packaging.

Modeling phase equilibria for acid gas mixtures using the CPA equation of state. Part II: Binary mixtures with CO2

DEFF Research Database (Denmark)

Tsivintzelis, Ioannis; Kontogeorgis, Georgios; Michelsen, Michael Locht

2011-01-01

In Part I of this series of articles, the study of H2S mixtures has been presented with CPA. In this study the phase behavior of CO2 containing mixtures is modeled. Binary mixtures with water, alcohols, glycols and hydrocarbons are investigated. Both phase equilibria (vapor–liquid and liquid–liqu...

Effect of temperature on acid–base equilibria in separation techniques. A review

International Nuclear Information System (INIS)

Gagliardi, Leonardo G.; Tascon, Marcos; Castells, Cecilia B.

2015-01-01

Studies on the theoretical principles of acid–base equilibria are reviewed and the influence of temperature on secondary chemical equilibria within the context of separation techniques, in water and also in aqueous-organic solvent mixtures, is discussed. In order to define the relationships between the retention in liquid chromatography or the migration velocity in capillary electrophoresis and temperature, the main properties of acid–base equilibria have to be taken into account for both, the analytes and the conjugate pairs chosen to control the solution pH. The focus of this review is based on liquid–liquid extraction (LLE), liquid chromatography (LC) and capillary electrophoresis (CE), with emphasis on the use of temperature as a useful variable to modify selectivity on a predictable basis. Simplified models were evaluated to achieve practical optimizations involving pH and temperature (in LLE and CE) as well as solvent composition in reversed-phase LC. - Highlights: • The study of theoretical principles of acid–base equilibrium has been reviewed. • The proton transfer process is often present in the analytical separation practice. • The influence of temperature on secondary chemical equilibria is examined. • The focus is laid on liquid chromatography and capillary electrophoresis. • Temperature can be a useful variable to modify selectivity under predictable basis

On Nash-Equilibria of Approximation-Stable Games

Science.gov (United States)

Awasthi, Pranjal; Balcan, Maria-Florina; Blum, Avrim; Sheffet, Or; Vempala, Santosh

One reason for wanting to compute an (approximate) Nash equilibrium of a game is to predict how players will play. However, if the game has multiple equilibria that are far apart, or ɛ-equilibria that are far in variation distance from the true Nash equilibrium strategies, then this prediction may not be possible even in principle. Motivated by this consideration, in this paper we define the notion of games that are approximation stable, meaning that all ɛ-approximate equilibria are contained inside a small ball of radius Δ around a true equilibrium, and investigate a number of their properties. Many natural small games such as matching pennies and rock-paper-scissors are indeed approximation stable. We show furthermore there exist 2-player n-by-n approximation-stable games in which the Nash equilibrium and all approximate equilibria have support Ω(log n). On the other hand, we show all (ɛ,Δ) approximation-stable games must have an ɛ-equilibrium of support O(Δ^{2-o(1)}/ɛ2{log n}), yielding an immediate n^{O(Δ^{2-o(1)}/ɛ^2log n)}-time algorithm, improving over the bound of [11] for games satisfying this condition. We in addition give a polynomial-time algorithm for the case that Δ and ɛ are sufficiently close together. We also consider an inverse property, namely that all non-approximate equilibria are far from some true equilibrium, and give an efficient algorithm for games satisfying that condition.

Experimental study of the phase equilibria in the Mg–Zn–Ag ternary system at 300 °C

Energy Technology Data Exchange (ETDEWEB)

Wang, Jian, E-mail: jian.wang@polymtl.ca [Center for Research in Computational Thermochemistry (CRCT), Department of Chemical Engineering, École Polytechnique, Montréal, Québec H3C 3A7 (Canada); Zhang, Yi-Nan [Department of Mechanical Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, Quebec H3G 1M8 (Canada); Hudon, Pierre; Jung, In-Ho [Department of Mining and Materials Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5 (Canada); Medraj, Mamoun [Department of Mechanical Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, Quebec H3G 1M8 (Canada); Department of Mechanical and Materials Engineering, Masdar Institute, Masdar City, P.O. Box 54224, Abu Dhabi (United Arab Emirates); Chartrand, Patrice [Center for Research in Computational Thermochemistry (CRCT), Department of Chemical Engineering, École Polytechnique, Montréal, Québec H3C 3A7 (Canada)

2015-08-05

Highlights: • The phase equilibria of Mg–Zn–Ag system at 300 °C were determined. • A bcc continuous ternary solid solution forms between MgAg (bcc-B2) and AgZn (bcc-A2) was determined. • The extended solid solubilities of the sub-binary compounds were also determined. - Abstract: The phase equilibria in the Mg–Zn–Ag ternary system at 300 °C were investigated using three diffusion couples and 35 key samples. Scanning electron microscopy (SEM) equipped with energy-dispersive spectroscope (EDS) and X-ray diffraction (XRD) techniques were used for homogeneity ranges and crystal structure determination. Large solid solubility limits, due to substitution among Mg, Zn and Ag atoms in Mg{sub 3}Ag and MgZn{sub 2} phases, were observed in the present work. Solid solubility limits of Ag and Zn in the hcp (Mg) phase were found to be less than 1 at.%. The extended solid solubilities of the Mg{sub 12}Zn{sub 13}, Mg{sub 2}Zn{sub 3}, MgZn{sub 2} (C14), Mg{sub 2}Zn{sub 11}, Ag{sub 5}Zn{sub 8} and hcp (AgZn{sub 3}) sub-binary compounds were also determined in the Mg–Zn–Ag ternary system. In addition, a bcc continuous ternary solid solution forms between MgAg (bcc-B2) and AgZn (bcc-A2) at 300 °C.

Thermodynamic analysis and phase equilibria investigation in Pb−Zn−Ag system

Directory of Open Access Journals (Sweden)

Mitovski Aleksandra M.

2010-01-01

Full Text Available Physico-chemical processes that take place during the refining process in the extractive metallurgy of lead, are connected with ternary Pb−Zn−Ag system, which is necessary to study from the theoretical practical and aspects. Such investigation is important from production point of view, because of the phenomena that occur during desilvering of lead which is one of the important stages during lead refining process. Process of lead desilvering binds to ternary system Pb−Zn−Ag, which was the reason for numerous investigations, both from thermodynamic point of view and in terms of testing and determining the phase diagram, bearing in mind the theoretical, and practical importance of knowledge about the processes which are going in investigated system. The paper presents the results of thermodynamic analysis and investigation of phase equilibria of the Pb−Zn−Ag ternary system using the method of thermodynamic predictions and phase diagrams calculations, respectively, and the experimental results of metalography obtained by optical microscopy. Phase diagram of the vertical section Pb−Zn80Ag20 is presented, obtained by CALPHAD calculation methodology, and using PANDAT thermodynamic software, compared to experimental results obtained by DTA analysis. The results show a pronounced break in solubility, which is characteristic for the whole ternary Pb−Zn−Ag system. Also, it can be noticed that the thermodynamic properties follow the behavior of this system, which is expressed through positive deviation of Raoult’s law, pointing to the lack of lead affinity compared to the other two components in the system. The optical microscopy results of the investigated system show the following: - Sample L1 (weight% Pb = 98: the structure of the observed section shows double eutectic (Pbsol+Zn−Agsol which lies in the base of the primary crystals of lead (Pbsol - Samples L2−L5: the structure consists of a dual eutectic (Pbsol+Zn−Agsol and

Uniqueness of Nash equilibria in a quantum Cournot duopoly game

International Nuclear Information System (INIS)

Sekiguchi, Yohei; Sakahara, Kiri; Sato, Takashi

2010-01-01

A quantum Cournot game whose classical form game has multiple Nash equilibria is examined. Although the classical equilibria fail to be Pareto optimal, the quantum equilibrium exhibits the following two properties: (i) if the measurement of entanglement between strategic variables chosen by the competing firms is sufficiently large, the multiplicity of equilibria vanishes, and (ii) the more strongly the strategic variables are entangled, the more closely the unique equilibrium approaches to the optimal one.

Computed phase equilibria for burnable neutron absorbing materials for advanced pressurized heavy water reactors

Energy Technology Data Exchange (ETDEWEB)

Corcoran, E.C. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000, St. Forces, Kingston, Ont., K7K 7B4 (Canada)], E-mail: emily.corcoran@rmc.ca; Lewis, B.J.; Thompson, W.T. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000, St. Forces, Kingston, Ont., K7K 7B4 (Canada); Hood, J. [Atomic Energy of Canada Ltd., Sheridan Park, 2251 Speakman Drive, Mississauga, Ont., L5K 1B2 (Canada); Akbari, F.; He, Z. [Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, Ont., K0J 1J0 (Canada); Reid, P. [Atomic Energy of Canada Ltd., Sheridan Park, 2251 Speakman Drive, Mississauga, Ont., L5K 1B2 (Canada)

2009-03-31

Burnable neutron absorbing materials are expected to be an integral part of the new fuel design for the Advanced CANDU [CANDU is as a registered trademark of Atomic Energy of Canada Limited.] Reactor. The neutron absorbing material is composed of gadolinia and dysprosia dissolved in an inert cubic-fluorite yttria-stabilized zirconia matrix. A thermodynamic model based on Gibbs energy minimization has been created to provide estimated phase equilibria as a function of composition and temperature. This work includes some supporting experimental studies involving X-ray diffraction.

Attractive evolutionary equilibria

NARCIS (Netherlands)

Joosten, Reinoud A.M.G.; Roorda, Berend

2011-01-01

We present attractiveness, a refinement criterion for evolutionary equilibria. Equilibria surviving this criterion are robust to small perturbations of the underlying payoff system or the dynamics at hand. Furthermore, certain attractive equilibria are equivalent to others for certain evolutionary

Direct phase coexistence molecular dynamics study of the phase equilibria of the ternary methane-carbon dioxide-water hydrate system.

Science.gov (United States)

Michalis, Vasileios K; Tsimpanogiannis, Ioannis N; Stubos, Athanassios K; Economou, Ioannis G

2016-09-14

Molecular dynamics simulation is used to predict the phase equilibrium conditions of a ternary hydrate system. In particular, the direct phase coexistence methodology is implemented for the determination of the three-phase coexistence temperature of the methane-carbon dioxide-water hydrate system at elevated pressures. The TIP4P/ice, TraPPE-UA and OPLS-UA forcefields for water, carbon dioxide and methane respectively are used, in line with our previous studies of the phase equilibria of the corresponding binary hydrate systems. The solubility in the aqueous phase of the guest molecules of the respective binary and ternary systems is examined under hydrate-forming conditions, providing insight into the predictive capability of the methodology as well as the combination of these forcefields to accurately describe the phase behavior of the ternary system. The three-phase coexistence temperature is calculated at 400, 1000 and 2000 bar for two compositions of the methane-carbon dioxide mixture. The predicted values are compared with available calculations with satisfactory agreement. An estimation is also provided for the fraction of the guest molecules in the mixed hydrate phase under the conditions examined.

A Systematic Identification Method for Thermodynamic Property Modelling

DEFF Research Database (Denmark)

Ana Perederic, Olivia; Cunico, Larissa; Sarup, Bent

2017-01-01

In this work, a systematic identification method for thermodynamic property modelling is proposed. The aim of the method is to improve the quality of phase equilibria prediction by group contribution based property prediction models. The method is applied to lipid systems where the Original UNIFAC...... model is used. Using the proposed method for estimating the interaction parameters using only VLE data, a better phase equilibria prediction for both VLE and SLE was obtained. The results were validated and compared with the original model performance...

Phase equilibria at low temperature for light hydrocarbons-methanol-water-acid gases mixtures: measurements and modelling; Equilibres de phases a basse temperature de systemes complexes CO{sub 2} - hydrocarbures legers - methanol - eau: mesures et modelisation

Energy Technology Data Exchange (ETDEWEB)

Ruffine, L.

2005-10-15

The need to develop and improve natural gas treatment processes is real. The petroleum industry usually uses separation processes which require phase equilibrium phenomena. Yet, the complexity of the phase equilibria involved results in a lack of data, which in turn limits the development of thermodynamic models. The first part of this work is devoted to experimental investigations for systems containing light hydrocarbons, methanol, water and acid gases. We present a new apparatus that was developed to measure vapor-liquid and vapor-liquid-liquid equilibria. It allowed us to obtain new phase composition data for the methanol-ethane binary system and different mixtures, and also to determine a part of the three phases equilibrium envelope of the same systems. In the second part of this work, we have developed a thermodynamic model based on the CPA equation of state. This choice may be justified by the presence of associating components like methanol, hydrogen sulfide and water in the systems. Such model is necessary for the design of gas treatment plants. Our model provides good results for phase equilibrium calculations for binaries systems without binary interaction parameter in many cases, and describes correctly the vapour-liquid and vapor-liquid-liquid equilibria for complex mixtures. (author)

Phase equilibria and thermodynamic properties of high-alloy tool steels : theoretical and experimental approach

OpenAIRE

Bratberg, Johan

2005-01-01

The recent development of tool steels and high-speed steels has led to a significant increase in alloy additions, such as Co, Cr, Mo, N, V, and W. Knowledge about the phase relations in these multicomponent alloys, that is, the relative stability between different carbides or the solubility of different elements in the carbides and in the matrix phase, is essential for understanding the behaviour of these alloys in heat treatments. This information is also the basis for improving the properti...

Experimental Phase Equilibria Studies of the Pb-Fe-O System in Air, in Equilibrium with Metallic Lead and at Intermediate Oxygen Potentials

Science.gov (United States)

Shevchenko, M.; Jak, E.

2017-12-01

The phase equilibria information on the Pb-Fe-O system is of practical importance for the improvement of the existing thermodynamic database of lead-containing slag systems (Pb-Zn-Fe-Cu-Si-Ca-Al-Mg-O). Phase equilibria of the Pb-Fe-O system have been investigated: (a) in air at temperatures between 1053 K and 1373 K (780 °C and 1100 °C); (b) in equilibrium with metallic lead at temperatures between 1053 K and 1373 K (780 °C and 1100 °C); and (c) at intermediate oxidation conditions for the liquid slag in equilibrium with two solids (spinel + magnetoplumbite), at temperatures between 1093 K and 1373 K (820 °C and 1100 °C). The high-temperature equilibration/quenching/electron probe X-ray microanalysis technique has been used to accurately determine the compositions of the phases in equilibrium in the system. The Pb and Fe concentrations in the phases were determined directly; preliminary thermodynamic modeling with FactSage was used to estimate the ferrous-to-ferric ratios and to present the results in the ternary diagram.

Experimental determination of the phase equilibria in the Co-Fe-Zr ternary system

International Nuclear Information System (INIS)

Wang, C.P.; Yu, Y.; Zhang, H.H.; Hu, H.F.; Liu, X.J.

2011-01-01

Research highlights: → We determined four isothermal sections of the Co-Fe-Zr system from 1000 o C to 1300 o C. → No ternary compound was found in the Co-Fe-Zr ternary system. → The solubility of Fe in the liquid phase at 1300 o C is extremely large. → The (Co, Fe) 2 Zr phase form the continuous solution from Co-Zr side to Fe-Zr side. → The solubility of Zr in the fcc (Co, Fe) phase is extremely small. - Abstract: The phase equilibria in the Co-Fe-Zr ternary system were investigated by means of optical microscopy (OM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) on equilibrated ternary alloys. Four isothermal sections of the Co-Fe-Zr ternary system at 1300 o C, 1200 o C, 1100 o C and 1000 o C were experimentally established. The experimental results indicate that (1) no ternary compound was found in this system; (2) the solubility of Fe in the liquid phase of the Co-rich corner at 1300 o C is extremely large; (3) the liquid phase in the Zr-rich corner and the (Co,Fe) 2 Zr phase form the continuous solid solutions from the Co-Zr side to the Fe-Zr side; (4) the solubility of Zr in the fcc (Co, Fe) phase is extremely small.

Modelling of phase equilibria for associating mixtures using an equation of state

International Nuclear Information System (INIS)

Ferreira, Olga; Brignole, Esteban A.; Macedo, Eugenia A.

2004-01-01

In the present work, the group contribution with association equation of state (GCA-EoS) is extended to represent phase equilibria in mixtures containing acids, esters, and ketones, with water, alcohols, and any number of inert components. Association effects are represented by a group-contribution approach. Self- and cross-association between the associating groups present in these mixtures are considered. The GCA-EoS model is compared to the group-contribution method MHV2, which does not take into account explicitly association effects. The results obtained with the GCA-EoS model are, in general, more accurate when compared to the ones achieved by the MHV2 equation with less number of parameters. Model predictions are presented for binary self- and cross-associating mixtures

(Liquid + liquid) equilibria for (water + 1-propanol or acetone + β-citronellol) at different temperatures

International Nuclear Information System (INIS)

Li, Hengde; Han, Yongtao; Huang, Cheng; Yang, Chufen

2015-01-01

Graphical abstract: (Liquid + liquid) equilibrium data for systems composed of β-citronellol and aqueous 1-propanol or acetone are presented. Distribution ratios of 1-propanol and acetone in the mixtures are examined. The effect of the temperature on the ternary (liquid + liquid) equilibria is evaluated and discussed. - Highlights: • Ternary (liquid + liquid) equilibria containing β-citronellol are presented. • Distribution ratios of 1-propanol and acetone in the mixtures are examined. • The effect on the temperature of the systems is evaluated and discussed. - Abstract: On this paper, experimental (liquid + liquid) equilibrium (LLE) results are presented for systems composed of β-citronellol and aqueous 1-propanol or acetone. To evaluate the phase separation properties of β-citronellol in aqueous mixtures, LLE values for the ternary systems (water + 1-propanol + β-citronellol) and (water + acetone + β-citronellol) were determined with a tie-line method at T = (283.15, 298.15, and 313.15 ± 0.02) K and atmospheric pressure. The reliability of the experimental tie-lines was verified by the Hand and Bachman equations. Ternary phase diagrams, distribution ratios of 1-propanol and acetone in the mixtures are shown. The effect of the temperature on the ternary (liquid + liquid) equilibria was examined and discussed. The experimental LLE values were satisfactorily correlated by extended UNIQUAC and modified UNIQUAC models

Attractive evolutionary equilibria

OpenAIRE

Roorda, Berend; Joosten, Reinoud

2011-01-01

We present attractiveness, a refinement criterion for evolutionary equilibria. Equilibria surviving this criterion are robust to small perturbations of the underlying payoff system or the dynamics at hand. Furthermore, certain attractive equilibria are equivalent to others for certain evolutionary dynamics. For instance, each attractive evolutionarily stable strategy is an attractive evolutionarily stable equilibrium for certain barycentric ray-projection dynamics, and vice versa.

Phase equilibria in the ternary In-Ni-Sn system at 700 °C.

Science.gov (United States)

Schmetterer, C; Zemanova, A; Flandorfer, H; Kroupa, A; Ipser, H

2013-04-01

The phase equilibria of the ternary system In-Ni-Sn were investigated experimentally at 700 °C using X-ray diffraction (XRD) and scanning electron microscopy (SEM) including electron micro probe analysis (EMPA) and energy dispersive X-ray spectroscopy (EDX). A corresponding isothermal section was established based on these results. This particular temperature was chosen because it allowed obtaining reliable results within reasonable time. The existence of the ternary phase InNi 6 Sn 5 was confirmed whereas the ternary compound In 2 NiSn, reported earlier in literature, was found to be part of a large solid solution field based on binary InNi. The ternary solubility of the binary phases was established, and continuous solid solutions were found between the isostructural phases Ni 3 Sn LT and InNi 3 as well as between Ni 3 Sn 2 HT and InNi 2 . In addition, this isothermal section could be well reproduced by CALPHAD modelling. The resulting calculated isotherm at 700 °C is presented, too, and compared with the experimental results.

A new transiently chaotic flow with ellipsoid equilibria

Science.gov (United States)

Panahi, Shirin; Aram, Zainab; Jafari, Sajad; Pham, Viet-Thanh; Volos, Christos; Rajagopal, Karthikeyan

2018-03-01

In this article, a simple autonomous transiently chaotic flow with cubic nonlinearities is proposed. This system represents some unusual features such as having a surface of equilibria. We shall describe some dynamical properties and behaviours of this system in terms of eigenvalue structures, bifurcation diagrams, time series, and phase portraits. Various behaviours of this system such as periodic and transiently chaotic dynamics can be shown by setting special parameters in proper values. Our system belongs to a newly introduced category of transiently chaotic systems: systems with hidden attractors. Transiently chaotic behaviour of our proposed system has been implemented and tested by the OrCAD-PSpise software. We have found a proper qualitative similarity between circuit and simulation results.

Development of measurement capabilities for the thermophysical properties of energy-related fluids. Annual report, December 1, 1992--November 30, 1993

Energy Technology Data Exchange (ETDEWEB)

Kayser, R.F.

1993-08-13

The measurement capabilities to be developed include new apparatus for transport properties, thermodynamic properties, phase equilibria, and dielectric properties. Specific capabilities are: Thermal conductivity apparatus, vibrating wire viscometer, dual-sinker densimeter, high-temperature vibrating tube densimeter, dynamic phase equilibria apparatus, apparatus for dilute solutions, total-enthalpy flow calorimeter. Benchmark measurements were made (no data given) on pure and mixed alternative refrigerants and their mixtures with lubricants, and other fluids.

Nash Equilibria in Symmetric Games with Partial Observation

DEFF Research Database (Denmark)

Bouyer, Patricia; Markey, Nicolas; Vester, Steen

2014-01-01

We investigate a model for representing large multiplayer games, which satisfy strong symmetry properties. This model is made of multiple copies of an arena; each player plays in his own arena, and can partially observe what the other players do. Therefore, this game has partial information...... and symmetry constraints, which make the computation of Nash equilibria difficult. We show several undecidability results, and for bounded-memory strategies, we precisely characterize the complexity of computing pure Nash equilibria (for qualitative objectives) in this game model....

Phase transitions on (liquid + liquid) equilibria for (water + 1-methylnaphthalene + light aromatic hydrocarbon) ternary systems at T = (563, 573, and 583) K

International Nuclear Information System (INIS)

Togo, Masaki; Inamori, Yoshiki; Shimoyama, Yusuke

2012-01-01

Highlights: ► Mixtures of (water + 1-methylnaphthalene + light aromatic hydrocarbon) are focused. ► Phase transition pressures on (liquid + liquid) equilibria were measured. ► Effects of aromatic hydrocarbons on phase transition pressure are investigated. ► Phase transition pressures are discussed using dielectric constants of hydrocarbons. - Abstract: Phase transitions for (water + 1-methylnaphthalene + light aromatic hydrocarbon) ternary systems are observed at their (liquid + liquid) equilibria at T = (563, 573, and 583) K and (8.6 to 25.0) MPa. The phase transition pressures at T = (563, 573, and 583) K were measured for the five species of light aromatic hydrocarbons, o-, m-, p-xylenes, ethylbenzene, and mesitylene. The measurements of the phase transition pressures were carried out by changing the feed mole fraction of water and 1-methylnaphthalene in water free, respectively. Effects of the feed mole fraction of water on the phase transition pressures are very small. Increasing the feed mole fraction of 1-methylnaphthalene results in decreasing the phase transition pressures at constant temperature. The slopes depending on the feed mole fraction for 1-methylnaphthalene at the phase transition pressures are decreased with increasing temperature for (water + 1-methylnaphthalene + p-xylene), (water + 1-methylnaphthalene + o-xylene), and (water + 1-methylnaphthalene + mesitylene) systems. For xylene isomers, the highest and lowest of the phase transition pressures are obtained in the case of p- and o-xylenes, respectively. The phase transition pressures for ethylbenzene are lower than those in the case of p-xylene. The similar phase transition pressures are given for p-xylene and mesitylene.

Multiple equilibria in a simple elastocapillary system

KAUST Repository

Taroni, Michele; Vella, Dominic

2012-01-01

properties two stable equilibria may exist, and show via numerical solutions of the dynamic model that it is the initial state of the system that determines which stable equilibrium is ultimately reached. © 2012 Cambridge University Press.

Phase equilibria constraints on models of subduction zone magmatism

Science.gov (United States)

Myers, James D.; Johnston, Dana A.

Petrologic models of subduction zone magmatism can be grouped into three broad classes: (1) predominantly slab-derived, (2) mainly mantle-derived, and (3) multi-source. Slab-derived models assume high-alumina basalt (HAB) approximates primary magma and is derived by partial fusion of the subducting slab. Such melts must, therefore, be saturated with some combination of eclogite phases, e.g. cpx, garnet, qtz, at the pressures, temperatures and water contents of magma generation. In contrast, mantle-dominated models suggest partial melting of the mantle wedge produces primary high-magnesia basalts (HMB) which fractionate to yield derivative HAB magmas. In this context, HMB melts should be saturated with a combination of peridotite phases, i.e. ol, cpx and opx, and have liquid-lines-of-descent that produce high-alumina basalts. HAB generated in this manner must be saturated with a mafic phase assemblage at the intensive conditions of fractionation. Multi-source models combine slab and mantle components in varying proportions to generate the four main lava types (HMB, HAB, high-magnesia andesites (HMA) and evolved lavas) characteristic of subduction zones. The mechanism of mass transfer from slab to wedge as well as the nature and fate of primary magmas vary considerably among these models. Because of their complexity, these models imply a wide range of phase equilibria. Although the experiments conducted on calc-alkaline lavas are limited, they place the following limitations on arc petrologic models: (1) HAB cannot be derived from HMB by crystal fractionation at the intensive conditions thus far investigated, (2) HAB could be produced by anhydrous partial fusion of eclogite at high pressure, (3) HMB liquids can be produced by peridotite partial fusion 50-60 km above the slab-mantle interface, (4) HMA cannot be primary magmas derived by partial melting of the subducted slab, but could have formed by slab melt-peridotite interaction, and (5) many evolved calc

Phase equilibria, crystal structure and properties of complex oxides in the Nd{sub 2}O{sub 3}–SrO–CoO system

Energy Technology Data Exchange (ETDEWEB)

Aksenova, T.V.; Efimova, T.G. [Department of Physical and Inorganic Chemistry, Institute of Natural Science and Mathematics, Ural Federal University, Lenin av., 51, Yekaterinburg 620000 (Russian Federation); Lebedev, O.I. [Laboratoire CRISMAT, ENSICAEN UMR6508, 6 Bd Maréchal Juin, Cedex 4, Caen 14050 (France); Elkalashy, Sh.I.; Urusova, A.S. [Department of Physical and Inorganic Chemistry, Institute of Natural Science and Mathematics, Ural Federal University, Lenin av., 51, Yekaterinburg 620000 (Russian Federation); Cherepanov, V.A., E-mail: v.a.cherepanov@urfu.ru [Department of Physical and Inorganic Chemistry, Institute of Natural Science and Mathematics, Ural Federal University, Lenin av., 51, Yekaterinburg 620000 (Russian Federation)

2017-04-15

The phase equilibria in the ½Nd{sub 2}O{sub 3}–SrO–CoO system were systematically studied at 1373 K in air. The intermediate phases formed in the ½Nd{sub 2}O{sub 3}–SrO–CoO system at 1373 K in air are: Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} (0.0≤x≤0.5 with orthorhombic structure, sp. gr. Pbnm and 0.6≤x≤0.95 whose structure was detected as cubic according to XRD sp. gr. Pm3m, but shown to be tetragonal by TEM due to the oxygen vacancy ordering), Nd{sub 2-y}Sr{sub y}CoO{sub 4-δ} (0.6≤y≤1.1 with tetragonal K{sub 2}NiF{sub 4}-type structure, sp. gr. I4/mmm) and Nd{sub 2-z}Sr{sub z}O{sub 3} (0.0≤z≤0.15 with hexagonal structure, sp. gr. P-3m1). The unit cell parameters for the single phase samples were refined by the Rietveld analysis. The changes of oxygen content in Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} (0.6≤x≤0.95) and Ruddlesden-Popper oxide Nd{sub 2-y}Sr{sub y}CoO{sub 4-δ} were examined by TGA. All were found to be oxygen deficient phases. High-temperature dilatometry allows calculating the thermal expansion coefficient and evaluating the chemical expansion coefficient at high temperature. The projection of isothermal-isobaric phase diagram for the Nd–Sr–Co–O system at 1373 K in air to the compositional triangle of metallic components has been constructed. The phase equilibria in the studied Nd–Sr–Co–O system were compared to La–Sr–Co–O and Nd–M–Co–O (M=Ca and Ba). - Graphical abstract: Crystal structure of vacancy ordered supercell for Nd{sub 0.2}Sr{sub 0.8}CoO{sub 3-δ} and projection of phase diagram for the Nd–Sr–Co–O system onto the triangle edge of metallic components at 1373 K in air. - Highlights: • The diagram for the Nd–Sr–Co–O system at 1373 K in air has been constructed. • The crystal structure of Nd{sub 1-x}Sr{sub x}CoO{sub 3-δ} and Nd{sub 2-y}Sr{sub y}CoO{sub 4±δ} was refined. • The formation of superstructure due to the oxygen vacancy ordering was proved. • The changes of oxygen

Thermophysical Properties and Phase Equilibria of Materials Systems

National Research Council Canada - National Science Library

Reeber, R

2002-01-01

.... In those regions experiments are difficult and data is often marginally reliable. In a series of papers, we have developed models for predicting these properties for a wide range of metals, ceramics and semiconductors...

An energy stable evolution method for simulating two-phase equilibria of multi-component fluids at constant moles, volume and temperature

KAUST Repository

Kou, Jisheng

2016-02-25

In this paper, we propose an energy-stable evolution method for the calculation of the phase equilibria under given volume, temperature, and moles (VT-flash). An evolution model for describing the dynamics of two-phase fluid system is based on Fick’s law of diffusion for multi-component fluids and the Peng-Robinson equation of state. The mobility is obtained from diffusion coefficients by relating the gradient of chemical potential to the gradient of molar density. The evolution equation for moles of each component is derived using the discretization of diffusion equations, while the volume evolution equation is constructed based on the mechanical mechanism and the Peng-Robinson equation of state. It is proven that the proposed evolution system can well model the VT-flash problem, and moreover, it possesses the property of total energy decay. By using the Euler time scheme to discretize this evolution system, we develop an energy stable algorithm with an adaptive choice strategy of time steps, which allows us to calculate the suitable time step size to guarantee the physical properties of moles and volumes, including positivity, maximum limits, and correct definition of the Helmhotz free energy function. The proposed evolution method is also proven to be energy-stable under the proposed time step choice. Numerical examples are tested to demonstrate efficiency and robustness of the proposed method.

Correlation of phase equilibria for water + hydrocarbon systems at high temperatures and pressures by cubic equation of state

Energy Technology Data Exchange (ETDEWEB)

Haruki, Masashi; Yahiro, Yukihito; Higashi, Hidenori; Iwai, Yoshio; Arai, Yasuhiko [Kyushu University, FUkuoka (Japan). Graduate School of Engineering

1999-08-01

A modified-Soave-Redlich-Kwong (MSRK) equation of state with an exponent-type mixing rule for the energy parameter and a conventional rule for the size parameter is applied to correlate the phase equilibria for four binary mixtures of water + hydrocarbon (benzene, hexane, decane, and dodecane) systems at high temperatures and pressures. It is noted that good correlation results are obtained by using the mixing rules with interaction parameters between unlike molecules. (author)

Melt-gas phase equilibria and state diagrams of the selenium-tellurium system

Science.gov (United States)

Volodin, V. N.; Trebukhov, S. A.; Burabaeva, N. M.; Nitsenko, A. V.

2017-05-01

The partial pressures of saturated vapor of the components in the Se-Te system are determined and presented in the form of temperature-concentration dependences from which the boundaries of the melt-gas phase transition are calculated at atmospheric pressure and vacuums of 2000 and 100 Pa. The existence of azeotropic mixtures is revealed. It is found that the points of inseparably boiling melts correspond to 7.5 at % of Se and 995°C at 101325 Pa, 10.9 at % at 673°C and 19.5 at % at 522°C in vacuums of 2000 and 100 Pa, respectively. A complete state diagram is constructed, including the fields of gas-liquid equilibria at atmospheric and low pressures, the boundaries of which allow us to assess the behavior of selenium and tellurium upon distillation fractionation.

Solid-state phase equilibria in the Fe-Pt-Pr ternary system at 1173 K

International Nuclear Information System (INIS)

Ren Jing; Gu Zhengfei; Cheng Gang; Zhou Huaiying

2005-01-01

The solid-state phase equilibria in the Fe-Pt-Pr ternary system at 1173 K (Pr ≤ 70%) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. The 1173 K isothermal section consists of 13 single-phase regions, 22 two-phase regions and 10 three-phase regions. At 1173 K, we have observed that the maximum solid solubility of Pt in α-Fe is below 1.5 at.% and the solid solution region of Pt in γ-Fe is from 2 to 35 at.%; the maximum solid solubility of Fe in Pt is 18 at.%. The maximum solubility of Fe in PrPt 5 , PrPt 3 , PrPt 2 , Pr 3 Pt 4 , PrPt, Pr 3 Pt 2 and Pr 7 Pt 3 is below 1 at.%. The maximum solubility of Pr in α-(Fe, Pt), γ-(Fe, Pt), FePt, FePt 3 and (Pt, Fe) (the solid solution of Fe in Pt) is 6, 2, 4, 4.5 and 1.5 at.%, respectively. In this work, it is found that the phase Pr 3 Pt 4 does not exist in the ternary system. The binary compounds Fe 7 Pr and Fe 2 Pr and any new ternary compounds were not observed

Nash Equilibria in Symmetric Graph Games with Partial Observation

DEFF Research Database (Denmark)

Bouyer, Patricia; Markey, Nicolas; Vester, Steen

2017-01-01

We investigate a model for representing large multiplayer games, which satisfy strong symmetry properties. This model is made of multiple copies of an arena; each player plays in his own arena, and can partially observe what the other players do. Therefore, this game has partial information...... and symmetry constraints, which make the computation of Nash equilibria difficult. We show several undecidability results, and for bounded-memory strategies, we precisely characterize the complexity of computing pure Nash equilibria for qualitative objectives in this game model....

Ternary (liquid + liquid) equilibria of {trifluorotris(perfluoroethyl)phosphate based ionic liquids + thiophene + heptane}

International Nuclear Information System (INIS)

Marciniak, Andrzej; Królikowski, Marek

2012-01-01

Highlights: ► Ternary (liquid + liquid) equilibria for 3 ionic liquid + thiophene + heptane systems. ► The influence of ionic liquid structure on phase diagrams is discussed. ► High selectivity for separation of heptane/thiophene is observed. - Abstract: Ternary (liquid + liquid) equilibria for three systems containing ionic liquids {(4-(2-methoxyethyl)-4-methylmorpholinium trifluorotris(perfluoroethyl)phosphate, 1-(2-methoxyethyl)-1-methylpiperidinium trifluorotris(perfluoroethyl)phosphate, 1-(2-methoxyethyl)-1-methylpyrrolidinium trifluorotris(perfluoroethyl)phosphate) + thiophene + heptane} have been determined at T = 298.15 K. All systems showed high solubility of thiophene in the ionic liquid and low solubility of heptane. The solute distribution coefficient and the selectivity were calculated for all systems. High values of selectivity were obtained. The experimental results have been correlated using NRTL model. The influence of ionic liquid structure on phase equilibria is discussed.

The heat-capacity of ilmenite and phase equilibria in the system Fe-T-O

Science.gov (United States)

Anovitz, Lawrence M.; Treiman, A.H.; Essene, E.J.; Hemingway, B.S.; Westrum, E.F.; Wall, V.J.; Burriel, R.; Bohlen, S.R.

1985-01-01

Low temperature adiabatic calorimetry and high temperature differential scanning calorimetry have been used to measure the heat-capacity of ilmenite (FeTiO3) from 5 to 1000 K. These measurements yield S2980 = 108.9 J/(mol ?? K). Calculations from published experimental data on the reduction of ilmenite yield ??2980(I1) = -1153.9 kJ/(mol ?? K). These new data, combined with available experimental and thermodynamic data for other phases, have been used to calculate phase equilibria in the system Fe-Ti-O. Calculations for the subsystem Ti-O show that extremely low values of f{hook}O2 are necessary to stabilize TiO, the mineral hongquiite reported from the Tao district in China. This mineral may not be TiO, and it should be re-examined for substitution of other elements such as N or C. Consideration of solid-solution models for phases in the system Fe-Ti-O allows derivation of a new thermometer/oxybarometer for assemblages of ferropseudobrookite-pseudobrookitess and hematite-ilmenitess. Preliminary application of this new thermometer/oxybarometer to lunar and terrestrial lavas gives reasonable estimates of oxygen fugacities, but generally yields subsolidus temperatures, suggesting re-equilibration of one or more phases during cooling. ?? 1985.

Thermodynamic calculation of Al-Gd and Al-Gd-Mg phase equilibria checked by key experiments

International Nuclear Information System (INIS)

Groebner, J.; Kevorkov, D.; Schmid-Fetzer, R.

2001-01-01

The binary Al-Gd and the ternary Al-Gd-Mg systems were calculated using the Calphad method. It is demonstrated that previous interpretation of ternary liquidus temperatures below 700 C must be related to other phase equilibria. The actual ternary liquidus temperatures are much higher, up to some 600 C above the previous interpretation in literature. They are widely governed by the high-melting compounds Al 2 Gd and Al 3 Gd with liquidus surfaces stretching far into the ternary system. A small number of key experiments in this work confirmed the calculated liquidus temperature and the phase relations. The available experimental data in literature fit excellently with the calculation in the binary Al-Gd system. In the ternary Al-Gd-Mg system, which is shown in several sections of the phase diagram, a good agreement can be observed too, considering the necessary reinterpretation of the liquidus temperatures suggested by Rokhlin et al. Ternary solubilities were not found experimentally. The ternary compound Al 4 GdMg (τ) forms in a ternary peritectic reaction at 761 C. (orig.)

Vapor-liquid equilibria for the acetone-ethanol-n-propanol-tert-butanol-water system

Energy Technology Data Exchange (ETDEWEB)

Tochigi, K.; Uchida, K.; Kojima, K.

1981-12-01

This study deals with the measurement of vapor-liquid equilibria for the five-component system acetone-ethanol-n-propanol-tert-butanol-water at 760 mmHg and prediction of vapor-liquid equilibria by the ASOG group contribution method. The five-component system in this work is composed of a part of the components obtained during ethanol production by vapor-phase hydration of ethylene. 6 refs.

Calculation of Binary Adsorption Equilibria: Hydrocarbons and Carbon Dioxide on Activated Carbon

DEFF Research Database (Denmark)

Marcussen, Lis; Krøll, A.

1999-01-01

Binary adsorption equilibria are calculated by means of a mathematical model for multicomponent mixtures combined with the SPD (Spreading Pressure Dependent) model for calculation of activity coefficients in the adsorbed phase. The model has been applied successfully for the adsorption of binary ...... mixtures of hydrocarbons and carbon dioxide on activated carbons. The model parameters have been determined, and the model has proven to be suited for prediction of adsorption equilibria in the investigated systems....

Ternary (liquid + liquid) equilibria of {bis(trifluoromethylsulfonyl)-amide based ionic liquids + butan-1-ol + water}

International Nuclear Information System (INIS)

Marciniak, Andrzej; Wlazło, Michał; Gawkowska, Joanna

2016-01-01

Highlights: • Ternary (liquid + liquid) equilibria for 3 ionic liquid + butanol + water systems. • The influence of ionic liquid structure on phase diagrams is discussed. • Influence of IL structure on S and β for butanol/water separation is discussed. - Abstract: Ternary (liquid + liquid) phase equilibria for 3 systems containing bis(trifluoromethylsulfonyl)-amide ionic liquids (1-buthyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)-amide, 1-(2-methoxyethyl)-1-methylpiperidinium bis(trifluoromethylsulfonyl)-amide, {1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluorylsulfonyl)-amide) + butan-1-ol + water} have been determined at T = 298.15 K. The selectivity and solute distribution ratio were calculated for investigated systems and compared with literature data for other systems containing ionic liquids. In each system total solubility of butan-1-ol and low solubility of water in the ionic liquid is observed. The experimental results have been correlated using NRTL model. The influence of the structure of ionic liquid on phase equilibria, selectivity and solute distribution ratio is shortly discussed.

Thermodynamic model for the phase equilibria of gases and brines. Example in the H{sub 2}S-H{sub 2}O-NaCl system

Energy Technology Data Exchange (ETDEWEB)

Martinez Reyes, Jose; Gonzalez Partida, Eduardo; Tinoco-Michel, Jorge A [Centro de Geociencias, Universidad Nacional Autonoma de Mexico Campo de Juriquilla, Qro., Mexico, apartado postal 76230 (Mexico); Perez, Renee J; Heidemann, Robert A [Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive, Calgary Alberta, T2N 1N4 (Canada)

2008-10-01

We present a thermodynamic model for the phase equilibria of gases and brines, which couples Henry's Law with the Soave-Redlich-Kwong equation of state to reproduce experimental data. In this communication we focus on the H{sub 2}S H{sub 2}O NaCl system.

Thermodynamic Modeling of Multi-phase Solid–Liquid Equilibria in Industrial-Grade Oils and Fats

DEFF Research Database (Denmark)

Hjorth, Jeppe Lindegaard; Miller, Rasmus L.; Woodley, John M.

2015-01-01

Compositional thermodynamic phase separation is investigated for industrial-grade vegetable oils with complex compositions. Solid–liquid equilibria have been calculated by utilizing the Margules 2-suffix activity-coefficient model in combination with minimization of the Gibb’s free energy...... of the system. On the basis of quasi-equilibrium solid-fat content (SFC) measurements, a new approach to the estimation of the interaction parameters, needed for the activity-coefficient model, has been developed. The parameters are fitted by matching the SFC of two oils at various degrees of dilution...... and isothermal temperatures. Subsequently, the parameters are successfully validated against three oils, rich in asymmetric and symmetric triacylglycerols (TAG), respectively. The new approach developed is shown to be very flexible, allowing incorporation of additional TAG and polymorphic states. It thereby...

Learning efficient correlated equilibria

KAUST Repository

Borowski, Holly P.

2014-12-15

The majority of distributed learning literature focuses on convergence to Nash equilibria. Correlated equilibria, on the other hand, can often characterize more efficient collective behavior than even the best Nash equilibrium. However, there are no existing distributed learning algorithms that converge to specific correlated equilibria. In this paper, we provide one such algorithm which guarantees that the agents\\' collective joint strategy will constitute an efficient correlated equilibrium with high probability. The key to attaining efficient correlated behavior through distributed learning involves incorporating a common random signal into the learning environment.

Learning efficient correlated equilibria

KAUST Repository

Borowski, Holly P.; Marden, Jason R.; Shamma, Jeff S.

2014-01-01

The majority of distributed learning literature focuses on convergence to Nash equilibria. Correlated equilibria, on the other hand, can often characterize more efficient collective behavior than even the best Nash equilibrium. However, there are no existing distributed learning algorithms that converge to specific correlated equilibria. In this paper, we provide one such algorithm which guarantees that the agents' collective joint strategy will constitute an efficient correlated equilibrium with high probability. The key to attaining efficient correlated behavior through distributed learning involves incorporating a common random signal into the learning environment.

Exogenous empirical-evidence equilibria in perfect-monitoring repeated games yield correlated equilibria

KAUST Repository

Dudebout, Nicolas; Shamma, Jeff S.

2014-01-01

This paper proves that exogenous empirical-evidence equilibria (xEEEs) in perfect-monitoring repeated games induce correlated equilibria of the associated one-shot game. An empirical-evidence equilibrium (EEE) is a solution concept for stochastic games. At equilibrium, agents' strategies are optimal with respect to models of their opponents. These models satisfy a consistency condition with respect to the actual behavior of the opponents. As such, EEEs replace the full-rationality requirement of Nash equilibria by a consistency-based bounded-rationality one. In this paper, the framework of empirical evidence is summarized, with an emphasis on perfect-monitoring repeated games. A less constraining notion of consistency is introduced. The fact that an xEEE in a perfect-monitoring repeated game induces a correlated equilibrium on the underlying one-shot game is proven. This result and the new notion of consistency are illustrated on the hawk-dove game. Finally, a method to build specific correlated equilibria from xEEEs is derived.

Exogenous empirical-evidence equilibria in perfect-monitoring repeated games yield correlated equilibria

KAUST Repository

Dudebout, Nicolas

2014-12-15

This paper proves that exogenous empirical-evidence equilibria (xEEEs) in perfect-monitoring repeated games induce correlated equilibria of the associated one-shot game. An empirical-evidence equilibrium (EEE) is a solution concept for stochastic games. At equilibrium, agents\\' strategies are optimal with respect to models of their opponents. These models satisfy a consistency condition with respect to the actual behavior of the opponents. As such, EEEs replace the full-rationality requirement of Nash equilibria by a consistency-based bounded-rationality one. In this paper, the framework of empirical evidence is summarized, with an emphasis on perfect-monitoring repeated games. A less constraining notion of consistency is introduced. The fact that an xEEE in a perfect-monitoring repeated game induces a correlated equilibrium on the underlying one-shot game is proven. This result and the new notion of consistency are illustrated on the hawk-dove game. Finally, a method to build specific correlated equilibria from xEEEs is derived.

Isothermal phase equilibria for the (HFC-32 + HFC-134a) mixed-gas hydrate system

International Nuclear Information System (INIS)

Miyauchi, Hiroshi; Yasuda, Kenjiro; Matsumoto, Yuuki; Hashimoto, Shunsuke; Sugahara, Takeshi; Ohgaki, Kazunari

2012-01-01

Highlights: ► Structural phase transition results in the heterogeneous azeotropic-like behaviour. ► HFC-134a molecules, in spite of an s-II former, occupy the large cages of s-I. ► Negative azeotropic-like behaviour becomes more remarkable at higher temperatures. - Abstract: Isothermal phase equilibria (pressure-composition relations in hydrate, gas, and aqueous phases) in the {difluoromethane (HFC-32) + 1,1,1,2-tetrafluoroethane (HFC-134a)} mixed-gas hydrate system were measured at the temperatures 274.15 K, 279.15 K, and 283.15 K. The heterogeneous azeotropic-like behaviour derived from the structural phase transition of (HFC-32 + HFC-134a) mixed-gas hydrates appears over the whole temperature range of the present study. In addition to the heterogeneous azeotropic-like behaviour, the isothermal phase equilibrium curves of the (HFC-32 + HFC-134a) mixed-gas hydrate system exhibit the negative homogeneous azeotropic-like behaviour at temperatures 279.15 K and 283.15 K. The negative azeotropic-like behaviour, which becomes more remarkable at higher temperatures, results in the lower equilibrium pressure of (HFC-32 + HFC-134a) mixed-gas hydrates than those of both simple HFC-32 and HFC-134a hydrates. Although the HFC-134a molecule forms the simple structure-II hydrate at the temperatures, the present findings reveal that HFC-134a molecules occupy a part of the large cages of the structure-I mixed-gas hydrate.

Determination of thermodynamic parameters of tautomerization in gas phase by mass spectrometry and DFT calculations: Keto-enol versus nitrile-ketenimine equilibria.

Science.gov (United States)

Giussi, Juan M; Gastaca, Belen; Albesa, Alberto; Cortizo, M Susana; Allegretti, Patricia E

2011-02-01

The study of tautomerics equilibria is really important because the reactivity of each compound with tautomeric capacity can be determined from the proportion of each tautomer. In the present work the tautomeric equilibria in some γ,δ-unsaturated β-hydroxynitriles and γ,δ-unsaturated β-ketonitriles were studied. The first family of compounds presents two possible theoretical tautomers, nitrile and ketenimine, while the second one presents four possible theoretical tautomers, keto-nitrile, enol (E and Z)-nitrile and keto-ketenimine. The equilibrium in gas phase was studied by gas chromatography-mass spectrometry (GC-MS). Tautomerization enthalpies were calculated by this methodology, and results were compared with those obtained by density functional theory (DFT) calculations, observing a good agreement between them. Nitrile tautomers were favored within the first family of compounds, while keto-nitrile tautomers were favored in the second family. Copyright © 2010 Elsevier B.V. All rights reserved.

Partial Cooperative Equilibria: Existence and Characterization

Directory of Open Access Journals (Sweden)

Amandine Ghintran

2010-09-01

Full Text Available We study the solution concepts of partial cooperative Cournot-Nash equilibria and partial cooperative Stackelberg equilibria. The partial cooperative Cournot-Nash equilibrium is axiomatically characterized by using notions of rationality, consistency and converse consistency with regard to reduced games. We also establish sufficient conditions for which partial cooperative Cournot-Nash equilibria and partial cooperative Stackelberg equilibria exist in supermodular games. Finally, we provide an application to strategic network formation where such solution concepts may be useful.

Stability of the n = 1 internal kink mode in equilibria with flows

International Nuclear Information System (INIS)

Aydemir, A.Y.; Waelbroeck, F.L.

1996-01-01

Stabilizing influence of mass flows, either directly or through their shearing action, on various modes is now generally recognized. Here we examine linear and nonlinear stability of the n = 1 internal kink mode in equilibria with toroidal rotation, using our nonlinear, initial-value MHD code CTD, which can be used to generate self-consistent equilibria with flows in arbitrary geometries. It is well known that equilibrium mass flows introduce complications in determination of MHD equilibria and their stability properties, such as the loss of self-adjointness and an increase in the number of conditions required to uniquely determine the equilibria. Thus, even with purely toroidal flows, an implicit statement about the equation of state is needed, in addition to a knowledge of the magnetic field and velocity profiles; rotation in an adiabatic plasma leads to a different equilibrium than, for example, in an isothermal one, with possibly quite different stability properties. We find that the expected stabilizing influence of toroidal rotation on n = 1 is generally absent in adiabatically generated equilibria in which, of all the relevant thermodynamic variables, only the specific entropy is a flux function, s = s (ψ). Fortunately, physically more relevant isothermal case where the temperature is constant on flux surfaces, T = T(ψ), has more favorable stability characteristics. On the other hand, an inconsistent but common practice of ignoring density perturbations, a benign omission for static equilibria, leads to overly optimistic results when equilibrium flows axe present, predicting stability when there may not be any. The crucial role played by the equation of state in determining equilibrium raises questions regarding the role of parallel transport in stability calculations; this and other nonideal effects, along with the role of plasma β vs. the rotational β, and nonlinear stability when the mode is pushed beyond marginality, will be discussed

Modeling of liquid phases

CERN Document Server

Soustelle, Michel

2015-01-01

This book is part of a set of books which offers advanced students successive characterization tool phases, the study of all types of phase (liquid, gas and solid, pure or multi-component), process engineering, chemical and electrochemical equilibria, and the properties of surfaces and phases of small sizes. Macroscopic and microscopic models are in turn covered with a constant correlation between the two scales. Particular attention has been given to the rigor of mathematical developments. This second volume in the set is devoted to the study of liquid phases.

Survey of the calculation of phase equilibria with the aid of the UNIFAC-method

Energy Technology Data Exchange (ETDEWEB)

Gmehling, J.; Rasmussen, P.; Fredenslund, A.

1981-09-01

In the design of diffusional separation processes and for many other practical purposes one needs quantitative estimates of phase equilibrium compositions. These compositions can today be predicted with good results using modern, two-parameter models for the excess Gibbs energy. However, since the number of different multicomponent mixtures of interest in chemical technology is very large, it is in practise often not possible to find experimental data in the literature for all the possible binary combinations. In these cases it is necessary to use a predictive approach. Today, group-contribution methods such as ASOG and UNIFAC may be used with confidence to predict liquid phase excess Gibbs energies. In these methods, the mixture is assumed to consist not of molecules but of the functional groups which, when added form the parent molecules. This has the advantage that a large number of mixtures of interest in chemical technology can be described in terms of relatively few parameters characterizing the interactions between the groups. This review article demonstrates the application of the UNIFAC method to various practical problems within phase equilibria. The UNIFAC method applies to mixtures of nonelectrolytes in the temperature range of 275-425 K and at pressures up to 10 bar.

Thermodynamic modelling of phase equilibria in Al–Ga–P–As system

Indian Academy of Sciences (India)

A generalized thermodynamic expression of the liquid Al–Ga–P–As alloys is used in conjunction with the solid solution model in determining the solid–liquid equilibria at 1173 K and 1273 K. The liquid solution model contains thirtyseven parameters. Twentyfour of them pertain to those of the six constituent binaries, twelve ...

α-NiPt(Al) and phase equilibria in the Ni-Al-Pt system at 1150 deg C

International Nuclear Information System (INIS)

Hayashi, S.; Ford, S.I.; Young, D.J.; Sordelet, D.J.; Besser, M.F.; Gleeson, B.

2005-01-01

The α-NiPt(Al) phase and its associated equilibria in the Ni-Al-Pt system at 1150 deg C were investigated by analyzing equilibrated bulk alloys and the interdiffusion zones of diffusion couples. Phase constitutions, tie-lines and microstructures were determined using a combination of techniques, including high-energy synchrotron X-ray diffraction, scanning electron microscopy and electron probe microanalysis. A large Pt solubility limit was found to exist in the β-NiAl, ∼42 at.%, and in γ'-Ni 3 Al, ∼32 at.%. The α-NiPt(Al) phase was found to have wide Pt solubility range of about 33-60 at.% and to skew along an almost constant Pt/Al ratio of 1.5. The α-NiPt(Al) has an ordered face-centered tetragonal L1 0 crystal structure, with the Al and Pt atoms found to be preferentially located in the corners and prismatic faces, respectively. The temperature dependence of the lattice parameters and unit cell volume of the α phase were also determined

Kinetic description of linear theta-pinch equilibria

International Nuclear Information System (INIS)

Batchelor, D.B.; Davidson, R.C.

1975-01-01

Equilibrium properties of linear theta-pinch plasmas are studied within the framework of the steady-state (o/x=0) Vlasov-Maxwell equations. The analysis is carried out for an infinitely long plasma column aligned parallel to an externally applied axial magnetic field Bsub(z)sup(ext)esub(z). Equilibrium properties are calculated for the class of rigid-rotor Vlasov equilibria, in which the th component distribution function (Hsub(perpendicular), Psub(theta), upsilonsub(z) depends on perpendicular energy H and canonical angular momentum Psub(theta), exclusively through the linear combination Hsub(perpendicular)-ωsub(j)Psub(theta), where ω;=const.=angular velocity of mean rotation. General equilibrium relations that pertain to the entire class of rigid-rotor Vlasov equilibria are discussed; and specific examples of sharp- and diffuse-boundary equilibrium configurations are considered. Rigid-rotor density and magnetic field profiles are compared with experimentally observed profiles. A general prescription is given for determining the functional dependence of the equilibrium distribution function on Hsub(perpendicular)-ωsub(j)Psub(theta) in circumstances, where the density profile or magnetic field profile is specified. (author)

Modelling of phase equilibria of glycol ethers mixtures using an association model

DEFF Research Database (Denmark)

Garrido, Nuno M.; Folas, Georgios; Kontogeorgis, Georgios

2008-01-01

Vapor-liquid and liquid-liquid equilibria of glycol ethers (surfactant) mixtures with hydrocarbons, polar compounds and water are calculated using an association model, the Cubic-Plus-Association Equation of State. Parameters are estimated for several non-ionic surfactants of the polyoxyethylene ...

MHD stability of vertically asymmetric tokamak equilibria

International Nuclear Information System (INIS)

Dalhed, H.E.; Grimm, R.C.; Johnson, J.L.

1981-03-01

The ideal MHD stability properties of a special class of vertically asymmetric tokamak equilibria are examined. The calculations confirm that no major new physical effects are introduced and the modifications can be understood by conventional arguments. The results indicate that significant departures from up-down symmetry can be tolerated before the reduction in β becomes important for reactor operation

Hydrostatic Equilibria of Rotating Stars with Realistic Equation of State

Science.gov (United States)

Yasutake, Nobutoshi; Fujisawa, Kotaro; Okawa, Hirotada; Yamada, Shoichi

Stars rotate generally, but it is a non-trivial issue to obtain hydrostatic equilibria for rapidly rotating stars theoretically, especially for baroclinic cases, in which the pressure depends not only on the density, but also on the temperature and compositions. It is clear that the stellar structures with realistic equation of state are the baroclinic cases, but there are not so many studies for such equilibria. In this study, we propose two methods to obtain hydrostatic equilibria considering rotation and baroclinicity, namely the weak-solution method and the strong-solution method. The former method is based on the variational principle, which is also applied to the calculation of the inhomogeneous phases, known as the pasta structures, in crust of neutron stars. We found this method might break the balance equation locally, then introduce the strong-solution method. Note that our method is formulated in the mass coordinate, and it is hence appropriated for the stellar evolution calculations.

(Liquid + liquid) equilibria of perfluorocarbons with fluorinated ionic liquids

International Nuclear Information System (INIS)

Martinho, S.; Araújo, J.M.M.; Rebelo, L.P.N.; Pereiro, A.B.; Marrucho, I.M.

2013-01-01

Highlights: • (Liquid + liquid) equilibria perfluorocarbons and fluorinated ionic liquids. • Non-Random Two Liquid model was successfully applied. • Thermodynamic functions that describe the solvation process were calculated. -- Abstract: In order to evaluate the feasibility of partially replace perfluorocarbons (PFCs) with fluorinated ionic liquids (FILs) in PFCs-in-water emulsions, usually used for biomedical purposes, herein the (liquid + liquid) phase equilibria of FILs containing fluorinated chains longer than four carbons with PFCs were carried out in a wide range of temperatures. With this goal in mind, two PFCs (perfluorooctane and perfluorodecalin) were selected and the (liquid + liquid) equilibria of the binary mixtures of these PFCs and FILs were studied at atmospheric pressure in a temperature range from T (293.15 to 343.15) K. For these studies, FILs containing ammonium, pyridinium and imidazolium cations and different anions with fluorocarbon alkyl chains between 4 and 8 were included. Additionally, Non-Random Two Liquid (NRTL) thermodynamic model was successfully applied to correlate the behaviour of the PFCs + FILs binary mixtures. Moreover, thermodynamic functions that describe the solvation process were calculated from the experimental data

Cryptographically Blinded Games: Leveraging Players' Limitations for Equilibria and Profit

DEFF Research Database (Denmark)

Hubacek, Pavel; Park, Sunoo

2014-01-01

In this work we apply methods from cryptography to enable mutually distrusting players to implement broad classes of mediated equilibria of strategic games without trusted mediation. Our implementation uses a pre-play 'cheap talk' phase, consisting of non- binding communication between players...

Simulation of the high-pressure phase equilibria of hydrocarbon-water/brine systems

DEFF Research Database (Denmark)

Zuo, You-Xiang; Stenby, Erling Halfdan; Guo, Tian-Min

1996-01-01

The major objectives of this work are: (1) extend the modified Patel-Teja (MPT) equation of state proposed for aqueous electrolyte systems (Zuo and Guo, 1991) to describe the liquid-liquid and vapor-liquid-liquid equilibria of hydrocarbon-water/brine systems through introducing an unconventional...

Phase equilibria in chemical reactive fluid mixtures

International Nuclear Information System (INIS)

Maurer, Gerd

2011-01-01

Downstream processing is a major part of nearly all processes in the chemical industries. Most separation processes in the chemical (and related) industries for fluid mixtures are based on phase equilibrium phenomena. The majority of separation processes can be modelled assuming that chemical reactions are of no (or very minor) importance, i.e., assuming that the overall speciation remains unchanged during a separation process. However, there are also a large number of industrially important processes where the thermodynamic properties are influenced by chemical reactions. The phase equilibrium of chemical reactive mixtures has been a major research area of the author's group over nearly 40 years. In this contribution, three examples from that research are discussed. The first example deals with the vapour phase dimerisation of carboxylic acids and its consequences on phase equilibrium phenomena and phase equilibrium predictions. The second example deals with the solubility of sour gases (e.g., carbon dioxide and sulfur dioxide) in aqueous solutions of ammonia. That topic has been of interest for many years, e.g., in relation with the gasification and liquefaction of coal and, more recently, with the removal of carbon dioxide from flue gas in the 'chilled ammonia process'. The third example deals with phase equilibrium phenomena in aqueous solutions of polyelectrolytes. It deals with the phenomenon of 'counter ion condensation' and methods to model the Gibbs free energy of such solutions.

Phase equilibrium engineering

CERN Document Server

Brignole, Esteban Alberto

2013-01-01

Traditionally, the teaching of phase equilibria emphasizes the relationships between the thermodynamic variables of each phase in equilibrium rather than its engineering applications. This book changes the focus from the use of thermodynamics relationships to compute phase equilibria to the design and control of the phase conditions that a process needs. Phase Equilibrium Engineering presents a systematic study and application of phase equilibrium tools to the development of chemical processes. The thermodynamic modeling of mixtures for process development, synthesis, simulation, design and

Prediction of multiphase equilibria in associating fluids by a contact-site quasichemical equation of state

International Nuclear Information System (INIS)

Prikhodko, I.V.; Victorov, A.I.; Loos, Th.W.de

1995-01-01

A contract-site quasichemical equation of state has been used for the modeling of different kinds of fluid phase equilibria (between a gas phase and one or more liquids) over a wide range of conditions. Among the systems of interest are the ternary mixtures water + alkanols + hydrocarbons (alkanes or alkynes), water + alkanols (or acetone) + CO 2 , water + polyoxyethyleneglycol ethers + heavy alkanes. The model has been applied to describing the thermodynamic properties of the binary subsystems and to predict the phase behavior of the ternary systems. For longer-chain alkanols and hydrocarbons a group-contribution approach is implemented, which allows the modeling when no experimental data are available. The model gives reasonable predictions of phase behavior and the correct trends in the calculated phase diagrams in most cases. The concentrations of associates in liquid and gas phases are estimated by the model and compared with some experimental and computer simulation data. The predictive abilities of the model, its limitations, and possible ways of its improvement are discussed

Some axisymmetric equilibria for certain ideal and resistive magnetohydrodynamics with incompressible flows

Directory of Open Access Journals (Sweden)

S.M. Moawad

Full Text Available In this paper, the equilibrium properties of some ideal and resistive magnetohydrodynamics (MHD are investigated. The governing equations are taken in the steady state for parallel and non-parallel flow to magnetic filed. The governing equations are reduced to Bernoulli-Grad-Shafranov system. The problem of finding exact equilibria to the governing equations in the presence of incompressible mass flows is studied. Several nonlinear equilibria of the governing equations are obtained with aid of constructed constraints. The obtained results cover several previously configurations and include new considerations about the nonlinearity of magnetic flux stream variables. The possibility of applying the obtained results to magnetic confinement devices are discussed. Keywords: Magnetohydrodynamics, Axisymmetric plasma, Resistivity, Incompressible flows, Exact equilibria, Magnetic confinement devices

The phase equilibria and thermal stability of the long-period stacking ordered phase in the Mg–Cu–Y system

International Nuclear Information System (INIS)

Jiang, Min; Su, Xiulan; Li, Hongxiao; Ren, Yuping; Qin, Gaowu

2014-01-01

Highlights: • 14H LPSO structure has been confirmed to be stable in the Mg–Cu–Y system. • Partial isothermal sections of the Mg–Cu–Y system from 300 to 450 °C have been established. • Reaction L + α-Mg ↔ 14H + Mg 2 Cu has been determined in the Mg–Cu–Y system. • The thermal stability of the 14H phase in the Mg–Cu–Y system has been well studied. - Abstract: Phase equilibria in the Mg-rich Mg–Cu–Y system at 300, 400 and 450 °C have been experimentally investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), electron probe micro-analyzer (EPMA) and transmission electron microscope (TEM). The results show that a long-period stacking ordered (LPSO) phase 14H is stable in the Mg–Cu–Y system, which is the only one ternary intermetallic compound that gets a thermodynamic equilibrium with the a-Mg phase. The equilibrium 14H phase has a very limited solid solution range, and can be nearly regarded as a ternary stoichiometric compound with a formulae as Mg 91 Cu 4 Y 5 . The thermal stability of the 14H phase in the Mg–Cu–Y system has been well studied, which shows that the 14H phase disappears varying from 442 °C to 490 °C depending on the alloy composition. The isothermal sections of the Mg-rich Mg–Cu–Y system at 300, 400 and 450 °C have been finally established, and moreover, a quasi-peritectic reaction L + α-Mg ↔ 14H + Mg 2 Cu has been determined occurring at 442 °C with an estimated liquid composition of Mg 77 Cu 18 Y 5

Gyrokinetic magnetohydrodynamics and the associated equilibria

Science.gov (United States)

Lee, W. W.; Hudson, S. R.; Ma, C. H.

2017-12-01

The gyrokinetic magnetohydrodynamic (MHD) equations, related to the recent paper by W. W. Lee ["Magnetohydrodynamics for collisionless plasmas from the gyrokinetic perspective," Phys. Plasmas 23, 070705 (2016)], and their associated equilibria properties are discussed. This set of equations consists of the time-dependent gyrokinetic vorticity equation, the gyrokinetic parallel Ohm's law, and the gyrokinetic Ampere's law as well as the equations of state, which are expressed in terms of the electrostatic potential, ϕ, and the vector potential, A , and support both spatially varying perpendicular and parallel pressure gradients and the associated currents. The corresponding gyrokinetic MHD equilibria can be reached when ϕ→0 and A becomes constant in time, which, in turn, gives ∇.(J∥+J⊥)=0 and the associated magnetic islands, if they exist. Examples of simple cylindrical geometry are given. These gyrokinetic MHD equations look quite different from the conventional MHD equations, and their comparisons will be an interesting topic in the future.

Quantifying geological uncertainty in metamorphic phase equilibria modelling; a Monte Carlo assessment and implications for tectonic interpretations

Directory of Open Access Journals (Sweden)

Richard M. Palin

2016-07-01

Full Text Available Pseudosection modelling is rapidly becoming an essential part of a petrologist's toolkit and often forms the basis of interpreting the tectonothermal evolution of a rock sample, outcrop, or geological region. Of the several factors that can affect the accuracy and precision of such calculated phase diagrams, “geological” uncertainty related to natural petrographic variation at the hand sample- and/or thin section-scale is rarely considered. Such uncertainty influences the sample's bulk composition, which is the primary control on its equilibrium phase relationships and thus the interpreted pressure–temperature (P–T conditions of formation. Two case study examples—a garnet–cordierite granofels and a garnet–staurolite–kyanite schist—are used to compare the relative importance that geological uncertainty has on bulk compositions determined via (1 X-ray fluorescence (XRF or (2 point counting techniques. We show that only minor mineralogical variation at the thin-section scale propagates through the phase equilibria modelling procedure and affects the absolute P–T conditions at which key assemblages are stable. Absolute displacements of equilibria can approach ±1 kbar for only a moderate degree of modal proportion uncertainty, thus being essentially similar to the magnitudes reported for analytical uncertainties in conventional thermobarometry. Bulk compositions determined from multiple thin sections of a heterogeneous garnet–staurolite–kyanite schist show a wide range in major-element oxides, owing to notable variation in mineral proportions. Pseudosections constructed for individual point count-derived bulks accurately reproduce this variability on a case-by-case basis, though averaged proportions do not correlate with those calculated at equivalent peak P–T conditions for a whole-rock XRF-derived bulk composition. The main discrepancies relate to varying proportions of matrix phases (primarily mica relative to

The Al-rich region of the Al-Mn-Ni alloy system. Part II. Phase equilibria at 620-1000 oC

International Nuclear Information System (INIS)

Balanetskyy, S.; Meisterernst, G.; Grushko, B.; Feuerbacher, M.

2011-01-01

Research highlights: → Phase equilibria in the Al-rich region of the Al-Mn-Ni alloy system were studied at 1000, 950, 850, 750, 700, 645 and 620 deg. C by means of SEM, TEM, powder XRD and DTA. → Three ternary thermodynamically stable intermetallics, the φ-phase (Al 5 Co 2 -type, hP26, P63/mmc; a = 0.76632(16), c = 0.78296(15) nm), the κ-phase (κ-Al 14.4 Cr 3.4 Ni l.1 -type, hP227, P63/m; a = 1.7625(10), c = 1.2516(10) nm), and the O-phase (O-Al 77 Cr 14 Pd 9 -type, Pmmn, oP650,: a = 2.3316(16), b = 1.2424(15), c = 3.2648(14) nm), as well as three ternary metastable phases, the decagonal D 3 -phase with periodicity about 1.25 nm, the Al 9 (Mn,Ni) 2 -phase (Al 9 Co 2 -type, P1121/a, mP22; a = 0.8585(16), b = 0.6269(9), c = 0.6205(11) nm, β = 95.34(10) o ) and the O 1 -phase (basecentered orthorhombic, a ∼ 23.8, b ∼ 12.4, c ∼ 32.2 nm) were revealed. → The existence of a thermodynamically stable R-phase of stoichiometry Al 60 Mn 11 Ni 4 , reported earlier in literature, was not confirmed in the present study. - Abstract: Phase equilibria in the Al-rich region of the Al-Mn-Ni alloy system were studied at 1000, 950, 850, 750, 700, 645 and 620 o C. Three ternary thermodynamically stable intermetallics, the φ-phase (Al 5 Co 2 -type, hP26, P6 3 /mmc; a = 0.76632(16), c = 0.78296(15) nm), the κ-phase (κ-Al 14.4 Cr 3.4 Ni l.1 -type, hP227, P6 3 /m; a = 1.7625(10), c = 1.2516(10) nm), and the O-phase (O-Al 77 Cr 14 Pd 9 -type, Pmmn, oP650,: a = 2.3316(16), b = 1.2424(15), c = 3.2648(14) nm), as well as three ternary metastable phases, the decagonal D 3 -phase with periodicity about 1.25 nm, the Al 9 (Mn,Ni) 2 -phase (Al 9 Co 2 -type, P112 1 /a, mP22; a = 0.8585(16), b = 0.6269(9), c = 0.6205(11) nm, β = 95.34(10) o ) and the O 1 -phase (base-centered orthorhombic, a ∼ 23.8, b ∼ 12.4, c ∼ 32.2 nm) were revealed. Their physicochemical behaviour in the Al-Mn-Ni alloy system was studied.

Adsorption analysis equilibria and kinetics

CERN Document Server

Do, Duong D

1998-01-01

This book covers topics of equilibria and kinetics of adsorption in porous media. Fundamental equilibria and kinetics are dealt with for homogeneous as well as heterogeneous particles. Five chapters of the book deal with equilibria and eight chapters deal with kinetics. Single component as well as multicomponent systems are discussed. In kinetics analysis, we deal with the various mass transport processes and their interactions inside a porous particle. Conventional approaches as well as the new approach using Maxwell-Stefan equations are presented. Various methods to measure diffusivity, such

Quantum equilibria for macroscopic systems

International Nuclear Information System (INIS)

Grib, A; Khrennikov, A; Parfionov, G; Starkov, K

2006-01-01

Nash equilibria are found for some quantum games with particles with spin-1/2 for which two spin projections on different directions in space are measured. Examples of macroscopic games with the same equilibria are given. Mixed strategies for participants of these games are calculated using probability amplitudes according to the rules of quantum mechanics in spite of the macroscopic nature of the game and absence of Planck's constant. A possible role of quantum logical lattices for the existence of macroscopic quantum equilibria is discussed. Some examples for spin-1 cases are also considered

First principles calculation of L21+A2 coherent equilibria in the Fe-Al-Ti system

International Nuclear Information System (INIS)

Alonso, Paula R.; Gargano, Pablo H.; Ramirez-Caballero, Gustavo E.; Balbuena, Perla B.; Rubiolo, Gerardo H.

2009-01-01

By combining first-principles density functional total energy calculations and statistical mechanics the ground state and the phase equilibria at finite temperatures of the ternary system Fe-Al-Ti have been investigated. Total energy calculations have been performed by means of the Wien 2k code to establish the ground state energetic. A cluster expansion method was therewith used to describe solid solutions. At several chosen finite temperatures the cluster variation method in the irregular tetrahedron approximation was employed in order to calculate the iron rich ternary bcc equilibria. It is confirmed that there are two kinds of phase separations of the bcc phase, A2+L2 1 and B2+L2 1 .

Magnetoacoustic heating and FCT-equilibria in the belt pinch

International Nuclear Information System (INIS)

Erckmann, V.

1983-02-01

In the HECTOR belt pinch of high β plasma is produced by magnetic compression in a Tokamak geometry. After compresseion the initial β value can be varied between 0.2 and 0.8. During 5 μs the plasma is further heated by a fast magnetoacoustic wave with a frequency near the first harmonic of the ion cyclotronfrequency. For the first time the β-value of a pinch plasma could be increased further from 0.34 after compression to 0.46 at the end of the rf-heating cycle. By proper selection of the final β-value the region for resonance absorption of the heating wave can be shifted. Strong heating (200 MW) has been observed in the cases, where the resonance region has been located in the center of the plasma. In deuterium discharges an increase in ion temperature is observed during the heating process, whereas the electrons are energetically decoupled, showing no temperature increase. Strong plasma losses are found in the 200 MW range after the rf-heating process. The dominant mechanisms are charge exchange collisions with neutral gas atoms. During rf-heating and the subsequent cooling phase the magnetic flux is frozen due to the high conductivity of the plasma. The observed equilibria could be identified as flux conserving Tokamak (FCT) equilibria. Based on a two-dimensional code the time-evolution of the equilibria has been calculated. The q-profiles are time-independent, with increasing β the magnetic axis of the plasma is shifted towards the outer boundary of the torus, and finally the linear relation between β and βsub(pol), which is characteristic for low-β-equilibria, is no longer valid. Thus for the first time the existence of FCT-equilibria at high β has been demonstrated experimentally together with a qualitative agreement with FCT-theory. (orig./AH) [de

Jump conditions in transonic equilibria

International Nuclear Information System (INIS)

Guazzotto, L.; Betti, R.; Jardin, S. C.

2013-01-01

In the present paper, the numerical calculation of transonic equilibria, first introduced with the FLOW code in Guazzotto et al.[Phys. Plasmas 11, 604 (2004)], is critically reviewed. In particular, the necessity and effect of imposing explicit jump conditions at the transonic discontinuity are investigated. It is found that “standard” (low-β, large aspect ratio) transonic equilibria satisfy the correct jump condition with very good approximation even if the jump condition is not explicitly imposed. On the other hand, it is also found that high-β, low aspect ratio equilibria require the correct jump condition to be explicitly imposed. Various numerical approaches are described to modify FLOW to include the jump condition. It is proved that the new methods converge to the correct solution even in extreme cases of very large β, while they agree with the results obtained with the old implementation of FLOW in lower-β equilibria.

MINTEQ, Geochemical Equilibria in Ground Water

International Nuclear Information System (INIS)

Krupka, K.M.

1990-01-01

1 - Description of program or function: MINTEQ is a geochemical program to model aqueous solutions and the interactions of aqueous solutions with hypothesized assemblages of solid phases. It was developed for the Environmental Protection Agency to perform the calculations necessary to simulate the contact of waste solutions with heterogeneous sediments or the interaction of ground water with solidified wastes. MINTEQ can calculate ion speciation/solubility, adsorption, oxidation-reduction, gas phase equilibria, and precipitation/dissolution of solid phases. MINTEQ can accept a finite mass for any solid considered for dissolution and will dissolve the specified solid phase only until its initial mass is exhausted. This ability enables MINTEQ to model flow-through systems. In these systems the masses of solid phases that precipitate at earlier pore volumes can be dissolved at later pore volumes according to thermodynamic constraints imposed by the solution composition and solid phases present. The ability to model these systems permits evaluation of the geochemistry of dissolved traced metals, such as low-level waste in shallow land burial sites. MINTEQ was designed to solve geochemical equilibria for systems composed of one kilogram of water, various amounts of material dissolved in solution, and any solid materials that are present. Systems modeled using MINTEQ can exchange energy and material (open systems) or just energy (closed systems) with the surrounding environment. Each system is composed of a number of phases. Every phase is a region with distinct composition and physically definable boundaries. All of the material in the aqueous solution forms one phase. The gas phase is composed of any gaseous material present, and structurally distinct solid forms a separate phase. 2 - Method of solution: MINTEQ applies the fundamental principles of thermodynamics to solve geochemical equilibria from a set of mass balance equations, one for each component. Because the

A new approach to establish both stable and metastable phase equilibria for fcc ordered/disordered phase transition: application to the Al–Ni and Ni–Si systems

International Nuclear Information System (INIS)

Yuan Xiaoming; Zhang Lijun; Du Yong; Xiong Wei; Tang Ying; Wang Aijun; Liu Shuhong

2012-01-01

Both two-sublattice (2SL) and four-sublattice (4SL) models in the framework of the compound energy formalism can be used to describe the fcc ordered/disordered transitions. When transferring the parameters of 2SL disregarding the metastable ordered states into those of 4SL, inconsistence in either stable or metastable phase diagrams could appear, as detected in both Al–Ni and Ni–Si systems. To avoid such a kind of drawback, this behavior was analyzed and investigated in the Ni–Si and Al–Ni systems with the aid of first–principle calculations. Furthermore, a new approach considering both the stable and metastable fcc ordered phase equilibria deduced from the first–principles calculations was proposed to perform a reliable thermodynamic modeling for the fcc ordered/disordered transition. The Ni–Si system was then thermodynamically assessed using the presently proposed approach. The good agreement between the calculation and experiments demonstrates the reliability of the proposed approach. It is expected that the approach is valid for other systems showing complex ordered/disordered transitions. - Highlights: ► We discuss the drawbacks of order/disorder modeling in the Ni–Si and Al–Ni systems. ► We perform ab initio calculation of thermodynamic properties in the Ni–Si system. ► A CALPHAD–type approach is proposed to model the fcc ordered/disordered transition. ► The Ni–Si system was thermodynamically assessed using the new approach.

Monosilicide-disilicide-silicon phase equilibria in the nickel-platinum-silicon and nickel-palladium-silicon systems

Science.gov (United States)

Loomans, M. E.; Chi, D. Z.; Chua, S. J.

2004-10-01

Bulk-phase equilibria in Ni-rich/Si-rich alloys of the Ni-Pt-Si and Ni-Pd-Si systems were investigated. Results suggest that a bulk monosilicide solid solution, containing up to at least 11 at. pct Pt, exists in the Ni-Pt-Si system. Monosilicides containing more than 11 at. pct Pt were not examined. Results from both ternary systems point convincingly to the existence of a NiSi+Si↔NiSi2 eutectoid reaction near 700 °C in the Ni-Si binary system; data from the Ni-Pt-Si system, which yield the more accurate determination of the eutectoid temperature, place it at roughly 710 °C. The Pt and Pd concentrations of monosilicide in equilibrium with disilicide and Si were measured using energy-dispersive spectrometry (EDS) and were found to increase with temperature.

Quantum equilibria for macroscopic systems

Energy Technology Data Exchange (ETDEWEB)

Grib, A [Department of Theoretical Physics and Astronomy, Russian State Pedagogical University, St. Petersburg (Russian Federation); Khrennikov, A [Centre for Mathematical Modelling in Physics and Cognitive Sciences Vaexjoe University (Sweden); Parfionov, G [Department of Mathematics, St. Petersburg State University of Economics and Finances (Russian Federation); Starkov, K [Department of Mathematics, St. Petersburg State University of Economics and Finances (Russian Federation)

2006-06-30

Nash equilibria are found for some quantum games with particles with spin-1/2 for which two spin projections on different directions in space are measured. Examples of macroscopic games with the same equilibria are given. Mixed strategies for participants of these games are calculated using probability amplitudes according to the rules of quantum mechanics in spite of the macroscopic nature of the game and absence of Planck's constant. A possible role of quantum logical lattices for the existence of macroscopic quantum equilibria is discussed. Some examples for spin-1 cases are also considered.

Modelling the phase equilibria of multicomponent mixtures containing CO₂, alkanes, water, and/or alcohols using the quadrupolar CPA equation of state

DEFF Research Database (Denmark)

Bjørner, Martin Gamel; Kontogeorgis, Georgios

2016-01-01

In this work, a quadrupolar cubic plus association (qCPA) equation of state is evaluated for its ability to predict the phase equilibria of multicomponent mixtures containing CO2 and alkanes, alcohols, and/or water. A single binary interaction parameter is employed in qCPA for all binary combinat...... CPA yields the best results of all the models for the prediction of dew point pressures....

Phase equilibria in the Ni–Al–Ga system at 700 °C

International Nuclear Information System (INIS)

Belyavina, N.; Markiv, V.; Nakonechna, O.; Lozovyi, F.

2014-01-01

Graphical abstract: - Highlights: • We study phase equilibria in ternary Ni–Al–Ga in the whole concentration range. • Ni(Al,Ga), Ni 2 (Al,Ga) 3 , Ni 5 (Al,Ga) 3 extended solid solutions exist in this system. • Isothermal section (700 °C) of the Ni–Al–Ga system has been constructed. • Small additions of Ga increase compressive strength of Ni 3 (Al,Ga) solid solution. - Abstract: Phase relations in the ternary Ni–Al–Ga system at 700 °C have been established by the X-ray powder diffraction methods. In addition to already known Ni 3 (Al,Ga) continuous solid solution, Ni(Al,Ga) continuous solid solution as well as Ni 2 (Al,Ga) 3 and Ni 5 (Al,Ga) 3 extended solid solutions were found to exist in this system. It was shown that the ternary Ni 2 (Al,Ga) 3 and Ni 5 (Al,Ga) 3 compounds do not belong to the continuous solid solutions because of two-phase gaps on the Ni 2 Al 3 –Ni 2 Ga 3 (∼30–50 at.% Ga) and Ni 5 Al 3 –Ni 5 Ga 3 (∼12–25 at.% Ga) isolines at 700 °C. Some crystal structure peculiarities such as atomic ordering–disordering and presence of structural vacancies have been revealed for all solid solutions existing in the Ni–Al–Ga system. It was found that the compressive strength of the Ni 3 (Al,Ga) solid solution increases with small additions of gallium (about 2.5 at.%). The isothermal section (700 °C) of the ternary Ni–Al–Ga system including four extended solid solutions (Ni 3 (Al,Ga), Ni 5 (Al,Ga) 3 , Ni(Al,Ga) and Ni 2 (Al,Ga) 3 ) has been constructed and plotted

Axisymmetric ideal magnetohydrodynamic equilibria with incompressible flows

International Nuclear Information System (INIS)

Tasso, H.; Throumoulopoulos, G.N.

1997-12-01

It is shown that the ideal MHD equilibrium states of an axisymmetric plasma with incompressible flows are governed by an elliptic partial differential equation for the poloidal magnetic flux function ψ containing five surface quantities along with a relation for the pressure. Exact equilibria are constructed including those with non vanishing poloidal and toroidal flows and differentially varying radial electric fields. Unlike the case in cylindrical incompressible equilibria with isothermal magnetic surfaces which should have necessarily circular cross sections [G. N. Throumoulopoulos and H. Tasso, Phys. Plasmas 4, 1492 (1997)], no restriction appears on the shapes of the magnetic surfaces in the corresponding axisymmetric equilibria. The latter equilibria satisfy a set of six ordinary differential equations which for flows parallel to the magnetic field B can be solved semianalytically. In addition, it is proved the non existence of incompressible axisymmetric equilibria with (a) purely poloidal flows and (b) non-parallel flows with isothermal magnetic surfaces and vertical stroke B vertical stroke = vertical stroke B vertical stroke (ψ) (omnigenous equilibria). (orig.)

Spectrum Allocation for Decentralized Transmission Strategies: Properties of Nash Equilibria

Directory of Open Access Journals (Sweden)

Peter von Wrycza

2009-01-01

Full Text Available The interaction of two transmit-receive pairs coexisting in the same area and communicating using the same portion of the spectrum is analyzed from a game theoretic perspective. Each pair utilizes a decentralized iterative water-filling scheme to greedily maximize the individual rate. We study the dynamics of such a game and find properties of the resulting Nash equilibria. The region of achievable operating points is characterized for both low- and high-interference systems, and the dependence on the various system parameters is explicitly shown. We derive the region of possible signal space partitioning for the iterative water-filling scheme and show how the individual utility functions can be modified to alter its range. Utilizing global system knowledge, we design a modified game encouraging better operating points in terms of sum rate compared to those obtained using the iterative water-filling algorithm and show how such a game can be imitated in a decentralized noncooperative setting. Although we restrict the analysis to a two player game, analogous concepts can be used to design decentralized algorithms for scenarios with more players. The performance of the modified decentralized game is evaluated and compared to the iterative water-filling algorithm by numerical simulations.

Performance of predictive models in phase equilibria of complex associating systems: PC-SAFT and CEOS/GE

Directory of Open Access Journals (Sweden)

N. Bender

2013-03-01

Full Text Available Cubic equations of state combined with excess Gibbs energy predictive models (like UNIFAC and equations of state based on applied statistical mechanics are among the main alternatives for phase equilibria prediction involving polar substances in wide temperature and pressure ranges. In this work, the predictive performances of the PC-SAFT with association contribution and Peng-Robinson (PR combined with UNIFAC (Do through mixing rules are compared. Binary and multi-component systems involving polar and non-polar substances were analyzed. Results were also compared to experimental data available in the literature. Results show a similar predictive performance for PC-SAFT with association and cubic equations combined with UNIFAC (Do through mixing rules. Although PC-SAFT with association requires less parameters, it is more complex and requires more computation time.

Isothermal sections of phase equilibria diagrams for systems (terbium, dysprosium, holmium)-molybdenum-boron at 1273 K

International Nuclear Information System (INIS)

Kuz'ma, Yu.B.; Zakharchuk, N.P.; Maksimova, L.T.

1988-01-01

The methods of X-ray analysis are used to study the R-Mo-B (R-Tb, Dy, Ho) systems and isothermal sections of phase equilibria diagrams at 1273 K are plotted. A formation of RMoB 4 (structure of the YCrB 4 type) is confirmed and borides R 3 MoB 7 (structure of the Er 3 CrB 7 type) and ∼ RMo 4 B 8 (of the unknown structure) are obtained for the first time. Borides DyMoB 3 and HoMoB 3 are of the ErMoB 3 structure. Lattice periods of new compounds are indicated. Diffractogrammes of borides Dy 3 MoB 7 and DyMoB 3 are calculated. A peculiarity of components interaction in the systems rare-earth metal-molybdenum-boron is considered

Isobaric (vapor + liquid) equilibria of 1-ethyl-3-methylimidazolium ethylsulfate plus (propionaldehyde or valeraldehyde): Experimental data and prediction

International Nuclear Information System (INIS)

Alvarez, Victor H.; Mattedi, Silvana; Aznar, Martin

2011-01-01

Research highlights: → We report density, refraction index, and VLE for (propionaldehyde or valeraldehyde) + [emim][EtSO 4 ]. → The Peng -Robinson + Wong -Sandler + COSMO-SAC model was used to predict density and VLE. → The densities were predicted with deviations below than 2.3%. → The experimental VLE was predicted with deviations below than 1.6%. - Abstract: This paper reports the density, refraction index, and (vapor + liquid) equilibria (VLE) for binary systems {aldehyde + 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO 4 ])}: {propionaldehyde + [emim][EtSO 4 ]} and {valeraldehyde + [emim][EtSO 4 ]}. The uncertainties for the temperature, pressure, and compositions measurements for the phase equilibria are ±0.1 K, ±0.01 kPa and ±0.0004, respectively. A qualitative analysis of the variation of the properties with changes in solvent and temperature was performed. The Peng-Robinson equation of state (PR EoS), coupled with the Wong-Sandler mixing rule (WS), is used to describe the experimental data. To calculate activity coefficients we used three different models: NRTL, UNIQUAC, and COSMO-SAC. Since the predictive liquid activity coefficient model COSMO-SAC is used in the Wong-Sandler mixing rule, the resulting thermodynamic model is a completely predictive one. The prediction results for the density and for the (vapor + liquid) equilibria have a deviation lower than 2.3% and 1.6%, respectively. The (vapor + liquid) equilibria predictions show a good description for the propionaldehyde system and only a qualitative description for the valeraldehyde system.

Multiple equilibria in a simple elastocapillary system

KAUST Repository

Taroni, Michele

2012-09-28

We consider the elastocapillary interaction of a liquid drop placed between two elastic beams, which are both clamped at one end to a rigid substrate. This is a simple model system relevant to the problem of surface-tension-induced collapse of flexible micro-channels that has been observed in the manufacture of microelectromechanical systems (MEMS). We determine the conditions under which the beams remain separated, touch at a point, or stick along a portion of their length. Surprisingly, we show that in many circumstances multiple equilibrium states are possible. We develop a lubrication-type model for the flow of liquid out of equilibrium and thereby investigate the stability of the multiple equilibria. We demonstrate that for given material properties two stable equilibria may exist, and show via numerical solutions of the dynamic model that it is the initial state of the system that determines which stable equilibrium is ultimately reached. © 2012 Cambridge University Press.

Physico-Chemical Properties and Phase Behaviour of Pyrrolidinium-Based Ionic Liquids

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Urszula Domańska

2010-04-01

Full Text Available A review of the relevant literature on 1-alkyl-1-methylpyrrolidinium-based ionic liquids has been presented. The phase diagrams for the binary systems of {1-ethyl-1-methylpyrrolidinium trifluoromethanesulfonate (triflate [EMPYR][CF3SO3] + water, or + 1-butanol} and for the binary systems of {1-propyl-1-methylpyrrolidinium trifluoromethanesulfonate (triflate [PMPYR][CF3SO3] + water, or + an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol} have been determined at atmospheric pressure using a dynamic method. The influence of alcohol chain length was discussed for the [PMPYR][CF3SO3]. A systematic decrease in the solubility was observed with an increase of the alkyl chain length of an alcohol. (Solid + liquid phase equilibria with complete miscibility in the liquid phase region were observed for the systems involving water and alcohols. The solubility of the ionic liquid increases as the alkyl chain length on the pyrrolidinium cation increases. The correlation of the experimental data has been carried out using the Wilson, UNIQUAC and the NRTL equations. The phase diagrams reported here have been compared to the systems published earlier with the 1-alkyl-1-methylpyrrolidinium-based ionic liquids. The influence of the cation and anion on the phase behaviour has been discussed. The basic thermal properties of pure ILs, i.e., melting temperature and the enthalpy of fusion, the solid-solid phase transition temperature and enthalpy have been measured using a differential scanning microcalorimetry technique.

High-Temperature Phase Equilibria of Duplex Stainless Steels Assessed with a Novel In-Situ Neutron Scattering Approach

Science.gov (United States)

Pettersson, Niklas; Wessman, Sten; Hertzman, Staffan; Studer, Andrew

2017-04-01

Duplex stainless steels are designed to solidify with ferrite as the parent phase, with subsequent austenite formation occurring in the solid state, implying that, thermodynamically, a fully ferritic range should exist at high temperatures. However, computational thermodynamic tools appear currently to overestimate the austenite stability of these systems, and contradictory data exist in the literature. In the present work, the high-temperature phase equilibria of four commercial duplex stainless steel grades, denoted 2304, 2101, 2507, and 3207, with varying alloying levels were assessed by measurements of the austenite-to-ferrite transformation at temperatures approaching 1673 K (1400 °C) using a novel in-situ neutron scattering approach. All grades became fully ferritic at some point during progressive heating. Higher austenite dissolution temperatures were measured for the higher alloyed grades, and for 3207, the temperature range for a single-phase ferritic structure approached zero. The influence of temperatures in the region of austenite dissolution was further evaluated by microstructural characterization using electron backscattered diffraction of isothermally heat-treated and quenched samples. The new experimental data are compared to thermodynamic calculations, and the precision of databases is discussed.

Formation and 'self-healing' of magnetic islands in finite-β Helias equilibria

International Nuclear Information System (INIS)

Hayashi, T.; Sato, T.; Merkel, P.; Nuehrenberg, J.; Schwenn, U.

1994-01-01

The behaviour of finite-pressure-induced magnetic islands is numerically analyzed for three-dimensional magnetohydrodynamic equilibria of the Helias configuration by using a three-dimensional equilibrium code. It is found that an island chain is generated on the 5/6 rational surface, when such a surface appears in the plasma region of the finite-β equilibrium. The island chain, however, is not so dangerous as to destroy the plasma confinement even if it appears in a vanishingly small shear region. Thus, a high β equilibrium with clear magnetic surfaces can be realized. Moreover, it is definitely confirmed that the finite pressure effect sometimes exhibits an unexpectedly good aspect, namely, that the vacuum islands are removed as β increases, which can be called 'self-healing' of islands. This property can be explained by the numerically discovered fact that the phases of islands induced by the finite-pressure effect are always locked in the same phase regardless of β. (author)

Assessment of solid/liquid equilibria in the (U, Zr)O

NARCIS (Netherlands)

Mastromarino, S.; Seibert, AF; Hashem, E.; Ciccioli, A.; Prieur, Damien; Scheinost, Andreas C.; Stohr, S.; Lajarge, P; Boshoven, JG; Robba, D.; Ernstberger, M; Bottomley, D.; Manara, D

2017-01-01

Solid/liquid equilibria in the system UO₂–ZrO₂ are revisited in this work by laser heating coupled with fast optical thermometry. Phase transition points newly measured under inert gas are in fair agreement with the early measurements performed by Wisnyi et al., in 1957, the

Multiple equilibria of divertor plasmas

International Nuclear Information System (INIS)

Vu, H.X.; Prinja, A.K.

1993-01-01

A one-dimensional, two-fluid transport model with a temperature-dependent neutral recycling coefficient is shown to give rise to multiple equilibria of divertor plasmas (bifurcation). Numerical techniques for obtaining these multiple equilibria and for examining their stability are presented. Although these numerical techniques have been well known to the scientific community, this is the first time they have been applied to divertor plasma modeling to show the existence of multiple equilibria as well as the stability of these solutions. Numerical and approximate analytical solutions of the present one-dimensional transport model both indicate that there exists three steady-state solutions corresponding to (1) a high-temperature, low-density equilibrium, (2) a low-temperature, high-density equilibrium, and (3) an intermediate-temperature equilibrium. While both the low-temperature and the high-temperature equilibria are stable, with respect to small perturbations in the plasma conditions, the intermediate-temperature equilibrium is physically unstable, i.e., any small perturbation about this equilibrium will cause a transition toward either the high-temperature or low-temperature equilibrium

Oxygen potentials and phase equilibria of the quaternary Y-Ba-Cu-O system in the region involving the YBa2Cu3O7-x phase

International Nuclear Information System (INIS)

Fitzner, K.; Musbah, O.; Hsieh Kerchang; Zhang Minxian; Chang, Y.A.

1993-01-01

The equilibrium oxygen potentials of four-phase equilibria (counting only the condensed phases) in the CuO-Cu 2 O-BaCuO 2 -Y 2 BaCuO 5 (211)-YBa 2 Cu 3 O 7-x (123) phase region were determined using the following solid-oxide electrolyte e.m.f. cell: Pt10Rh, air (psub(O 2 )=0.21 atm) vertical stroke ZrO 2 +Y 2 O 3 vertical stroke mixtures of oxides, Pt. The oxide mixtures whose oxygen potentials were measured were CuO-Cu 2 O-211-123, CuO-Cu 2 O-BaCuO 2 -123, Cu 2 O-BaCuO 2 -211-123 and CuO-BaCuO 2 -211-123. The phase in some of the mixtures were identified by X-ray diffraction. These data were analyzed and are presented using stability diagrams, i.e., oxygen potential as a function of the reciprocal of the temperature. Extrapolation of these data for the four four-phase equilibra to high temperatures yields a metastable five-phase equilibrium, i.e., 123=CuO+Cu 2 O+BaCuO 2 +211, at ∼1243 K (970 ) and log psub(O 2 ) ∼ -1.21 (psub(O 2 )∼0.062 atm). (orig.)

Phase equilibria of carbon dioxide and methane gas-hydrates predicted with the modified analytical S-L-V equation of state

Directory of Open Access Journals (Sweden)

Span Roland

2012-04-01

Full Text Available Gas-hydrates (clathrates are non-stoichiometric crystallized solutions of gas molecules in the metastable water lattice. Two or more components are associated without ordinary chemical union but through complete enclosure of gas molecules in a framework of water molecules linked together by hydrogen bonds. The clathrates are important in the following applications: the pipeline blockage in natural gas industry, potential energy source in the form of natural hydrates present in ocean bottom, and the CO2 separation and storage. In this study, we have modified an analytical solid-liquid-vapor equation of state (EoS [A. Yokozeki, Fluid Phase Equil. 222–223 (2004] to improve its ability for modeling the phase equilibria of clathrates. The EoS can predict the formation conditions for CO2- and CH4-hydrates. It will be used as an initial estimate for a more complicated hydrate model based on the fundamental EoSs for fluid phases.

Modeling Phase Equilibria for Acid Gas Mixtures using the Cubic-Plus-Association Equation of State. 3. Applications Relevant to Liquid or Supercritical CO2 Transport

DEFF Research Database (Denmark)

Tsivintzelis, Ioannis; Ali, Shahid; Kontogeorgis, Georgios

2014-01-01

density data for both CO2 and CO2–water and for vapor–liquid equilibrium for mixtures of CO2 with various compounds present in transport systems. In all of these cases we consider various possibilities for modeling CO2 (inert, self-associating using two-, three-, and four sites) and the possibility......The CPA (cubic-plus-association) equation of state is applied in this work to a wide range of systems of relevance to CO2 transport. Both phase equilibria and densities over extensive temperature and pressure ranges are considered. More specifically in this study we first evaluate CPA against......” for applying CPA to acid gas mixtures. The overall conclusion is that CPA performs satisfactorily; the model in most cases correlates well binary data and predicts with good accuracy multicomponent vapor–liquid equilibria. Among the various approaches investigated, the best ones are when cross association...

Prediction of vapour-liquid equilibria for the kinetic study of processes based on synthesis gas

Energy Technology Data Exchange (ETDEWEB)

Di Serio, M.; Tesser, R.; Cozzolino, M.; Santacesaria, E. [Naples Univ., Napoli (Italy). Dept. of Chemistry

2006-07-01

Syngas is normally used in the production of a broad range of chemicals and fuels. In many of these processes multiphase reactors, gas-liquid or gas-liquid-solid are used. Kinetic studies in multiphase systems are often complicated by the non-ideal behaviour of reagents and/or products that are consistently partitioned between the liquid and the vapour phase. Moreover, as often kinetic data are collected in batch conditions for the liquid phase, activity coefficients of the partitioned components can consistently change during the time as a consequence of changing the composition of the reaction mixture. Therefore, it is necessary, in these cases, to known the vapor-liquid equilibria (VLE) in order to collect and to interpret correctly the kinetic data. The description of phase equilibria, at high pressures, is usually performed by means of an EOS (Equation of State) allowing the calculation of fugacity coefficients, for each component, in both phases and determining the partition coefficients but the EOS approach involves the experimental determination of the interaction parameters for all the possible binary system of the mixture. For multicomponent mixtures a complete experimental determination of vapourliquid equilibria is very hard, also considering the high pressure and temperatures used. Some predictive group contribution methods have been recently developed. In this paper, we will describe in detail the application of these methods to the methanol homologation, as an example, with the scope of determining more reliable kinetic parameters for this reaction. (orig.)

Neoclassical MHD equilibria with ohmic current

International Nuclear Information System (INIS)

Tokuda, Shinji; Takeda, Tatsuoki; Okamoto, Masao.

1989-01-01

MHD equilibria of tokamak plasmas with neoclassical current effects (neoclassical conductivity and bootstrap current) were calculated self-consistently. Neoclassical effects on JFT-2M tokamak plasmas, sustained by ohmic currents, were studied. Bootstrap currents flow little for L-mode type equilibria because of low attainable values of poloidal beta, β J . H-mode type equilibria give bootstrap currents of 30% ohmic currents for β J attained by JFT-2M and 100% for β J ≥ 1.5, both of which are sufficient to change the current profiles and the resultant MHD equilibria. Neoclassical conductivity which has roughly half value of the classical Spitzer conductivity brings peaked ohmic current profiles to yield low safety factor at the magnetic axis. Neoclassical conductivity reduces the value of effective Z(Z eff ) which is necessary to give the observed one-turn voltage but it needs impurities accumulating at the center when such peaked current profiles are not observed. (author)

Phase equilibria and thermodynamics of the Fe–Al–C system: Critical evaluation, experiment and thermodynamic optimization

International Nuclear Information System (INIS)

Phan, Anh Thu; Paek, Min-Kyu; Kang, Youn-Bae

2014-01-01

In order to provide an efficient tool to design alloy chemistry and processing conditions for high-strength, lightweight steel, an investigation of the Fe–Al–C ternary system was carried out by experimental phase diagram measurement and a CALPHAD thermodynamic analysis. Discrepancies between previously available experimental results and thermodynamic calculations were identified. The Fe–Al sub-binary system was re-optimized in order to obtain an accurate description of the liquid phase, while Gibbs energies of solid phases were mainly taken from a previous thermodynamic modeling. Phase equilibria among face-centered cubic (fcc)/body-centered cubic (bcc)/graphite/κ-carbide/liquid phases in the Fe–Al–C system in the temperature range from 1000 to 1400 °C were obtained by chemical equilibration followed by quenching, and subsequent composition analysis using electron probe microanalysis/inductively coupled plasma spectroscopy. By merging the revised Fe–Al binary description with existing Fe–C and Al–C binary descriptions, a complete thermodynamic description of the Fe–Al–C system was obtained in the present study. The modified quasi-chemical model in the pair approximation was used to model the liquid phase, while solid solutions were modeled using compound energy formalism. A2/B2 order/disorder transition in the bcc phase was taken into account. Compared with previously known experiments/thermodynamic modeling, a better agreement was obtained in the present study, regarding the stable region of fcc and the solidification thermal peak of a ternary alloy near the liquidus temperature. The obtained thermodynamic description also reproduced various types of experimental data in the Fe–Al–C system such as isothermal sections, vertical sections, liquidus projection, etc. The solidification of various steel grades was predicted and discussed

Learning to Play Efficient Coarse Correlated Equilibria

KAUST Repository

Borowski, Holly P.; Marden, Jason R.; Shamma, Jeff S.

2018-01-01

The majority of the distributed learning literature focuses on convergence to Nash equilibria. Coarse correlated equilibria, on the other hand, can often characterize more efficient collective behavior than even the best Nash equilibrium. However

Computation of liquid-liquid equilibria and phase stabilities: implications for RH-dependent gas/particle partitioning of organic-inorganic aerosols

Directory of Open Access Journals (Sweden)

A. Zuend

2010-08-01

Full Text Available Semivolatile organic and inorganic aerosol species partition between the gas and aerosol particle phases to maintain thermodynamic equilibrium. Liquid-liquid phase separation into an organic-rich and an aqueous electrolyte phase can occur in the aerosol as a result of the salting-out effect. Such liquid-liquid equilibria (LLE affect the gas/particle partitioning of the different semivolatile compounds and might significantly alter both particle mass and composition as compared to a one-phase particle. We present a new liquid-liquid equilibrium and gas/particle partitioning model, using as a basis the group-contribution model AIOMFAC (Zuend et al., 2008. This model allows the reliable computation of the liquid-liquid coexistence curve (binodal, corresponding tie-lines, the limit of stability/metastability (spinodal, and further thermodynamic properties of multicomponent systems. Calculations for ternary and multicomponent alcohol/polyol-water-salt mixtures suggest that LLE are a prevalent feature of organic-inorganic aerosol systems. A six-component polyol-water-ammonium sulphate system is used to simulate effects of relative humidity (RH and the presence of liquid-liquid phase separation on the gas/particle partitioning. RH, salt concentration, and hydrophilicity (water-solubility are identified as key features in defining the region of a miscibility gap and govern the extent to which compound partitioning is affected by changes in RH. The model predicts that liquid-liquid phase separation can lead to either an increase or decrease in total particulate mass, depending on the overall composition of a system and the particle water content, which is related to the hydrophilicity of the different organic and inorganic compounds. Neglecting non-ideality and liquid-liquid phase separations by assuming an ideal mixture leads to an overestimation of the total particulate mass by up to 30% for the composition and RH range considered in the six

Thermodynamic properties of fluid mixtures at high pressures and high temperatures. Application to high explosives and to phase diagrams of binary mixtures

International Nuclear Information System (INIS)

Pittion-Rossillon, Gerard

1982-01-01

The free energy for mixtures of about ten species which are chemically reacting is calculated. In order to have accurate results near the freezing line, excess properties are deduced from a modern statistical mechanics theory. Intermolecular potentials for like molecules are fitted to give good agreement with shock experiments in pure liquid samples, and mixture properties come naturally from the theory. The stationary Chapman-Jouguet detonation wave is calculated with a chemical equilibrium computer code and results are in good agreement with experiment for a lot of various explosives. One then study gas-gas equilibria in a binary mixture and show the extreme sensitivity of theoretical phase diagrams to the hypothesis of the model (author) [fr

Phase equilibria and homogeneity range of the high temperature superconducting compound (Bi,Pb)2+xSr2Ca2Cu3O10+δ

International Nuclear Information System (INIS)

Kaesche, S.

1995-01-01

For the superconducting cuprates (Bi,Pb) 2+x Sr 2 Ca 2 Cu 3 O 10+y phase equilibria, the homogeneity region, and the phase formation has been studied in the temperture range 800 to 890 C. Sintered samples were prepared by a solid state reaction starting from Bi 2 O 3 , PbO, CuO and carbonates CaCO 3 and SrCO 3 in a three-stage calcination process. For the phase identification polarization microscopy, X-ray diffraction and susceptibility measurements have been applied. Multi-phase regions were determined in the cross section of the quasi-ternary system (Bi,Pb) 2 O 3 -SrO-CaO-CuO with constant Bi/(Bi+Pb) ratio 0.84 taking into account the 2223-phase. The homogeneity region was determined as function of Sr, Ca, Bi and Pb concentration. Its maximum size was found at 850 C

Phase equilibria in M-X-X' and M-Al-X ternary systems (M-transition metal, X,X'-B,C,N,Si) and crystal chemistry of ternary compounds

International Nuclear Information System (INIS)

Gusev, A.I.

1996-01-01

The data on phase equilibria in the M-X-X' and M-Al-X ternary systems (M-transition metal of 3 to 8 groups, X-B,C, N, Si) have been considered and summarized. modern oxygen-free advanced ceramics is based on these ternary systems. Phase diagrams of the 130 ternary systems have been discussed, more than two hundred ternary phases forming in these systems have been systematized and described. The typical crystal structures of ternary compounds and phase have been considered, the common and distinctive features of these structures have been analysed. It has been shown that the ternary compounds with octahedral atomic groups XM 6 have a regions of homogeneity. Refs. 240

Phases, phase equilibria, and phase rules in low-dimensional systems

International Nuclear Information System (INIS)

Frolov, T.; Mishin, Y.

2015-01-01

We present a unified approach to thermodynamic description of one, two, and three dimensional phases and phase transformations among them. The approach is based on a rigorous definition of a phase applicable to thermodynamic systems of any dimensionality. Within this approach, the same thermodynamic formalism can be applied for the description of phase transformations in bulk systems, interfaces, and line defects separating interface phases. For both lines and interfaces, we rigorously derive an adsorption equation, the phase coexistence equations, and other thermodynamic relations expressed in terms of generalized line and interface excess quantities. As a generalization of the Gibbs phase rule for bulk phases, we derive phase rules for lines and interfaces and predict the maximum number of phases than may coexist in systems of the respective dimensionality

Ternary systems Sr-{Ni,Cu}-Si: Phase equilibria and crystal structure of ternary phases

International Nuclear Information System (INIS)

Nasir, Navida; Melnychenko-Koblyuk, Nataliya; Grytsiv, Andriy; Rogl, Peter; Giester, Gerald; Wosik, Jaroslaw; Nauer, Gerhard E.

2010-01-01

Phase relations were established in the Sr-poor part of the ternary systems Sr-Ni-Si (900 deg. C) and Sr-Cu-Si (800 deg. C) by light optical microscopy, electron probe microanalysis and X-ray diffraction on as cast and annealed alloys. Two new ternary compounds SrNiSi 3 (BaNiSn 3 -type) and SrNi 9-x Si 4+x (own-type) were found in the Sr-Ni-Si system along with previously reported Sr(Ni x Si 1-x ) 2 (AlB 2 -type). The crystal structure of SrNi 9-x Si 4+x (own-type, x=2.7, a=0.78998(3), c=1.1337(2) nm; space group P4/nbm) was determined from X-ray single crystal counter to be a low symmetry derivative of the cubic, parent NaZn 13 -type. At higher Si-content X-ray Rietveld refinements reveal the formation of a vacant site (□) corresponding to a formula SrNi 5.5 Si 6.5 □ 1.0 . Phase equilibria in the Sr-Cu-Si system are characterized by the compounds SrCu 2-x Si 2+x (ThCr 2 Si 2 -type), Sr(Cu x Si 1-x ) 2 (AlB 2 -type), SrCu 9-x Si 4+x (0≤x≤1.0; CeNi 8.5 Si 4.5 -type) and SrCu 13-x Si x (4≤x≤1.8; NaZn 13 -type). The latter two structure types appear within a continuous solid solution. Neither a type-I nor a type-IX clathrate compound was encountered in the Sr-{Cu,Ni}-Si systems. Structural details are furthermore given for about 14 new ternary compounds from related alloy systems with Ba. - Graphical abstract: The crystal structure of SrNi 9-x Si 4+x (own-type, x=2.7, a=0.78998(3), c=1.1337(2) nm; space group P4/nbm) was determined from X-ray single crystal counter to be a low symmetry derivative of the cubic, parent NaZn 13 -type and is related to CeNi 8.5 Si 4.5 -type.

Learning to Play Efficient Coarse Correlated Equilibria

KAUST Repository

Borowski, Holly P.

2018-03-10

The majority of the distributed learning literature focuses on convergence to Nash equilibria. Coarse correlated equilibria, on the other hand, can often characterize more efficient collective behavior than even the best Nash equilibrium. However, there are no existing distributed learning algorithms that converge to specific coarse correlated equilibria. In this paper, we provide one such algorithm, which guarantees that the agents’ collective joint strategy will constitute an efficient coarse correlated equilibrium with high probability. The key to attaining efficient correlated behavior through distributed learning involves incorporating a common random signal into the learning environment.

Multiple Equilibria in Noisy Rational Expectations Economies

DEFF Research Database (Denmark)

Pálvölgyi, Dömötör; Venter, Gyuri

with a continuous price function. However, we also construct a tractable class of equilibria with discontinuous prices that have very different economic implications, including (i) jumps and crashes, (ii) significant revisions in uninformed belief due to small changes in the market price, (iii) “upward......-sloping” demand curves, (iv) higher prices leading to future returns that are higher in expectation (price drift) and (v) more positively skewed. Discontinuous equilibria can be arbitrarily close to being fully-revealing. Finally, discontinuous equilibria with the same construction also exist in Hellwig (1980)....

Phase Equilibria Study in the TeO2-Na2O-SiO2 System in Air Between 723 K (500 °C) and 1473 K (1200 °C)

Science.gov (United States)

Santoso, Imam; Taskinen, Pekka

2016-08-01

Knowledge of phase equilibria in the TeO2-Na2O-SiO2 system at elevated temperatures is important for ceramic and glass industries and for improving the operation of the smelting process of tellurium-containing materials. A review of previous investigations has indicated, however, that there are omissions in the available datasets on the liquidus temperatures of the molten TeO2-Na2O-SiO2 mixtures. The employed experimental method included equilibration of mixtures made from high purity oxides, rapid quenching of the equilibrated samples in water and followed by compositional analysis of the phases using an electron probe X-ray microanalyzer. The liquidus and phase equilibria in the TeO2-SiO2, TeO2-Na2O, and SiO2-TeO2-Na2O systems have been studied for a wide range of compositions between 723 K (500 °C) and 1473 K (1200 °C) at TeO2, SiO2, and Na2SiO3 saturations. New data have been generated in the SiO2-TeO2-Na2O system at SiO2 saturation. The liquidus compositions in the TeO2-Na2O system at TeO2 saturation have been compared with the previous data and an assessed phase diagram.

Calculation of phase equilibria in the Na2SO4-K2SO4-Cs2SO4-H2O system at 25 deg C

International Nuclear Information System (INIS)

Filippov, V.K.; Kalinkin, A.M.; Vasin, S.K.

1990-01-01

Calculation results of solubility diagram and water activity in saturated solutions of Na 2 SO 4 -K 2 SO 4 -Cs 2 SO 4 -H 2 O system at 25 deg C are presented. It is shown that for the calculation of quaternary systems one can use the Pitzer equations. Solubility diagram for the system studied is plotted and data on composition and water activity of solutions saturated by two or three solid phases are given. Classification of nonvariant equilibria from the viewpoint of isomorphism of solubility and fusibility diagrams permits to depict the direction of phase processes during isothermal evaporation of water

Stability of relative equilibria of three vortices

DEFF Research Database (Denmark)

Aref, Hassan

2009-01-01

Three point vortices on the unbounded plane have relative equilibria wherein the vortices either form an equilateral triangle or are collinear. While the stability analysis of the equilateral triangle configurations is straightforward, that of the collinear relative equilibria is considerably mor...

Existence of pareto equilibria for multiobjective games without compactness

OpenAIRE

Shiraishi, Yuya; Kuroiwa, Daishi

2013-01-01

In this paper, we investigate the existence of Pareto and weak Pareto equilibria for multiobjective games without compactness. By employing an existence theorem of Pareto equilibria due to Yu and Yuan([10]), several existence theorems of Pareto and weak Pareto equilibria for the multiobjective games are established in a similar way to Flores-B´azan.

Computing Nash equilibria through computational intelligence methods

Science.gov (United States)

Pavlidis, N. G.; Parsopoulos, K. E.; Vrahatis, M. N.

2005-03-01

Nash equilibrium constitutes a central solution concept in game theory. The task of detecting the Nash equilibria of a finite strategic game remains a challenging problem up-to-date. This paper investigates the effectiveness of three computational intelligence techniques, namely, covariance matrix adaptation evolution strategies, particle swarm optimization, as well as, differential evolution, to compute Nash equilibria of finite strategic games, as global minima of a real-valued, nonnegative function. An issue of particular interest is to detect more than one Nash equilibria of a game. The performance of the considered computational intelligence methods on this problem is investigated using multistart and deflection.

Stochastic Equilibria under Imprecise Deviations in Terminal-Reward Concurrent Games

Directory of Open Access Journals (Sweden)

Patricia Bouyer

2016-09-01

Full Text Available We study the existence of mixed-strategy equilibria in concurrent games played on graphs. While existence is guaranteed with safety objectives for each player, Nash equilibria need not exist when players are given arbitrary terminal-reward objectives, and their existence is undecidable with qualitative reachability objectives (and only three players. However, these results rely on the fact that the players can enforce infinite plays while trying to improve their payoffs. In this paper, we introduce a relaxed notion of equilibria, where deviations are imprecise. We prove that contrary to Nash equilibria, such (stationary equilibria always exist, and we develop a PSPACE algorithm to compute one.

Convergence of solutions of a non-local phase-field system

Czech Academy of Sciences Publication Activity Database

Londen, S.-O.; Petzeltová, Hana

2011-01-01

Roč. 4, č. 3 (2011), s. 653-670 ISSN 1937-1632 R&D Projects: GA AV ČR(CZ) IAA100190606 Institutional research plan: CEZ:AV0Z10190503 Keywords : non-local phase-field systems * separation property * convergence to equilibria Subject RIV: BA - General Mathematics http://www.aimsciences.org/journals/displayArticles.jsp?paperID=5698

Elastic energy and metastable phase equilibria for coherent mixtures in cubic systems

International Nuclear Information System (INIS)

Williams, R.O.

1979-02-01

Expressions were derived for the elastic energy due to coherency for cubic systems for an isotropic structure and for (100) or (111) habit planes for a lamellar structure. For the metastable equilibria the usual tangent compositions are replaced by compositions that are tangent to the elastic energy curve. For a loss of coherency there is an energy decrease due to the elastic effects and a further decrease associated with compositional changes. Information contained within this treatment permits calculation of the x-ray diffraction effects for such structures

Phase equilibria in the iron oxide-cobalt oxide-phosphorus oxide system

Science.gov (United States)

De Guire, Mark R.; Prasanna, T. R. S.; Kalonji, Gretchen; O'Handley, Robert C.

1987-01-01

Two novel ternary compounds are noted in the present study of 1000 C solid-state equilibria in the Fe-Co-P-O system's Fe2O3-FePO4-Co3(Po4)2-CoO region: CoFe(PO4)O, which undergoes incongruent melting at 1130 C, and Co3Fe4(PO4)6, whose incongruent melting occurs at 1080 C. The liquidus behavior-related consequences of rapidly solidified cobalt ferrite formation from cobalt ferrite-phosphate melts are discussed with a view to spinel formation. It is suggested that quenching from within the spinel-plus-liquid region may furnish an alternative to quenching a homogeneous melt.

Modelling of phase equilibria and related properties of mixtures involving lipids

DEFF Research Database (Denmark)

Cunico, Larissa

Many challenges involving physical and thermodynamic properties in the production of edible oils and biodiesel are observed, such as availability of experimental data and realiable prediction. In the case of lipids, a lack of experimental data for pure components and also for their mixtures in open...

Strong Nash Equilibria and the Potential Maimizer

NARCIS (Netherlands)

van Megen, F.J.C.; Facchini, G.; Borm, P.E.M.; Tijs, S.H.

1996-01-01

A class of non cooperative games characterized by a `congestion e ect' is studied, in which there exists a strong Nash equilibrium, and the set of Nash equilibria, the set of strong Nash equilibria and the set of strategy pro les maximizing the potential function coincide.The structure of the class

Consistent Prediction of Properties of Systems with Lipids

DEFF Research Database (Denmark)

Cunico, Larissa; Ceriani, Roberta; Sarup, Bent

Equilibria between vapour, liquid and/or solid phases, pure component properties and also the mixture-phase properties are necessary for synthesis, design and analysis of different unit operations found in the production of edible oils, fats and biodiesel. A systematic numerical analysis....... Lipids are found in almost all mixtures involving edible oils, fats and biodiesel. They are also being extracted for use in the pharma-industry. A database for pure components (lipids) present in these processes and mixtures properties has been developed and made available for different applications...... (model development, property verification, property prediction, etc.). The database has verified data for fatty acids, acylglycerols, fatty esters, fatty alcohols, vegetable oils, biodiesel and minor compounds as phospholipids, tocopherols, sterols, carotene and squalene, together with a user friendly...

Determination of structural, thermodynamic and phase properties in the Na2S-H2O system for application in a chemical heat pump

International Nuclear Information System (INIS)

Boer, R. de; Haije, W.G.; Veldhuis, J.B.J.

2002-01-01

Structural, thermodynamic and phase properties in the Na 2 S-H 2 O system for application in a chemical heat pump have been investigated using XRD, TG/DTA and melting point and vapour pressure determinations. Apart from the known crystalline phases Na 2 S·9H 2 O, Na 2 S·5H 2 O and Na 2 S a new phase Na 2 S·2H 2 O has been proven to exist. Na 2 S·((1)/(2))H 2 O is not a phase but a 3:1 mixture of Na 2 S and Na 2 S·2H 2 O, presumably stabilised by very slow dehydration kinetics. The vapour pressure-temperature equilibria of the sodium sulphide hydrates have been determined and a consistent set of thermodynamic functions for these compounds has been derived. XRD measurements indicate the topotactic character of the transitions between the hydration states

Free-boundary perturbed MHD equilibria

International Nuclear Information System (INIS)

Nührenberg, C

2012-01-01

The concept of perturbed ideal MHD equilibria [Boozer A H and Nuhrenberg C 2006 Phys. Plasmas 13 102501] is employed to study the influence of external error-fields and of small plasma-pressure changes on toroidal plasma equilibria. In tokamak and stellarator free-boundary calculations, benchmarks were successful of the perturbed-equilibrium version of the CAS3D stability code [Nührenberg C et al. 2009 Phys. Rev. Lett. 102 235001] with the ideal MHD equilibrium code NEMEC [Hirshman S P et al. 1986 Comput. Phys. Commun. 43 143].

Surface current equilibria from a geometric point of view

International Nuclear Information System (INIS)

Kaiser, R.; Salat, A.

1993-04-01

This paper addresses the inverse problem of the existence of surface current MHD equilibria in toroidal geometry with vanishing magnetic field inside. Inverse means that the plasma-vacuum interface rather than the external wall or conductors are given and the latter remain to be determined. This makes a reformulation of the problem possible in geometric terms: What toroidal surfaces with analytic parameterization allow a simple analytic covering by geodesics? If such a covering by geodesics (field lines) exists, their orthogonal trajectories (current lines) also form a simple covering and are described by a function satisfying a nonlinear partial differential equation of the Hamilton-Jacobi type whose coefficients are combinations of the metric elements of the surface. All known equilibria - equilibria with zero and infinite rotational transform and the symmetric ones in the case of finite rotational transform - turn out to be solutions of separable cases of that equation and allow a unified description if the toroidal surface is parametrized in the moving trihedral associated with a closed curve. Analogously to volume current equilibria, the only continuous symmetries compatible with separability are plane, helical and axial symmetry. In the nonseparable case numerical evidence is presented for cases with chaotic behaviour of geodesics, thus restricting possible equilibria for these surfaces. For weak deviation from axisymmetry KAM-type behaviour is observed, i.e. destruction of geodesic coverings with a low rational rotational transform and preservation of those with irrational rotational transform. A previous attempt to establish three-dimensional surface current equilibria on the basis of the KAM theorem is rejected as incomplete, and a complete proof of the existence of equilibria in the weakly nonaxisymmetric case, based on the twist theorem for mappings, is given. Finally, for a certain class of strong deviations from axisymmetry an analytic criterion is

Nash Equilibria in Fisher Market

Science.gov (United States)

Adsul, Bharat; Babu, Ch. Sobhan; Garg, Jugal; Mehta, Ruta; Sohoni, Milind

Much work has been done on the computation of market equilibria. However due to strategic play by buyers, it is not clear whether these are actually observed in the market. Motivated by the observation that a buyer may derive a better payoff by feigning a different utility function and thereby manipulating the Fisher market equilibrium, we formulate the Fisher market game in which buyers strategize by posing different utility functions. We show that existence of a conflict-free allocation is a necessary condition for the Nash equilibria (NE) and also sufficient for the symmetric NE in this game. There are many NE with very different payoffs, and the Fisher equilibrium payoff is captured at a symmetric NE. We provide a complete polyhedral characterization of all the NE for the two-buyer market game. Surprisingly, all the NE of this game turn out to be symmetric and the corresponding payoffs constitute a piecewise linear concave curve. We also study the correlated equilibria of this game and show that third-party mediation does not help to achieve a better payoff than NE payoffs.

Isotope effects in ion-exchange equilibria in aqueous and mixed solvent systems

International Nuclear Information System (INIS)

Gupta, A.R.

1979-01-01

Isotope effects in ion-exchange equilibria in aqueous and mixed solvents are analyzed in terms of the general features of ion-exchange equilibria and of isotope effects in chemical equilibria. The special role of solvent fractionation effects in ion-exchange equilibria in mixed solvents is pointed out. The various situations arising in isotope fractionation in ion exchange in mixed solvents due to solvent fractionation effects are theoretically discussed. The experimental data on lithium isotope effects in ion-exchange equilibria in mixed solvents are shown to conform to the above situations. The limitations of ion-exchange equilibria in mixed solvents for isotope fractionation are pointed out. 3 tables

Two-dimensional phase fraction charts

International Nuclear Information System (INIS)

Morral, J.E.

1984-01-01

A phase fraction chart is a graphical representation of the amount of each phase present in a system as a function of temperature, composition or other variable. Examples are phase fraction versus temperature charts used to characterize specific alloys and as a teaching tool in elementary texts, and Schaeffler diagrams used to predict the amount of ferrite in stainless steel welds. Isothermal-transformation diagrams (TTT diagrams) are examples that give phase (or microconstituent) amount versus temperature and time. The purpose of this communication is to discuss the properties of two-dimensional phase fraction charts in more general terms than have been reported before. It is shown that they can represent multi-component, multiphase equilibria in a way which is easier to read and which contains more information than the isotherms and isopleths of multi-component phase diagrams

Measurement and modeling of high-pressure (vapour + liquid) equilibria of (CO{sub 2} + alcohol) binary systems

Energy Technology Data Exchange (ETDEWEB)

Gutierrez, Jorge E.; Bejarano, Arturo [Departamento de Ingenieria Quimica y Ambiental, Universidad Tecnica Federico Santa Maria, Avda. Espana 1680, Valparaiso (Chile); Fuente, Juan C. de la, E-mail: juan.delafuente@usm.c [Departamento de Ingenieria Quimica y Ambiental, Universidad Tecnica Federico Santa Maria, Avda. Espana 1680, Valparaiso (Chile); Centro Regional de Estudios en Alimentos Saludables, Blanco 1623, Valparaiso (Chile)

2010-05-15

An apparatus based on a static-analytic method assembled in this work was utilized to perform high pressure (vapour + liquid) equilibria measurements with uncertainties estimated at <5%. Complementary isothermal (vapour + liquid) equilibria results are reported for the (CO{sub 2} + 1-propanol), (CO{sub 2} + 2-methyl-1-propanol), (CO{sub 2} + 3-methyl-1-butanol), and (CO{sub 2} + 1-pentanol) binary systems at temperatures of (313, 323, and 333) K, and at pressure range of (2 to 12) MPa. For all the (CO{sub 2} + alcohol) systems, it was visually monitored to insure that there was no liquid immiscibility at the temperatures and pressures studied. The experimental results were correlated with the Peng-Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapour + liquid) equilibria compositions were found to be in good agreement with the experimental values with deviations for the mol fractions <0.12 and <0.05 for the liquid and vapour phase, respectively.

The heat capacity of a natural monticellite and phase equilibria in the system CaO-MgO-SiO2-CO2

Science.gov (United States)

Sharp, Z.D.; Essene, E.J.; Anovitz, Lawrence M.; Metz, G.W.; Westrum, E.F.; Hemingway, B.S.; Valley, J.W.

1986-01-01

The heat capacity of a natural monticellite (Ca1.00Mg.09Fe.91Mn.01Si0.99O3.99) measured between 9.6 and 343 K using intermittent-heating, adiabatic calorimetry yields Cp0(298) and S2980 of 123.64 ?? 0.18 and 109.44 ?? 0.16 J ?? mol-1 K-1 respectively. Extrapolation of this entropy value to end-member monticellite results in an S0298 = 108.1 ?? 0.2 J ?? mol-1 K-1. High-temperature heat-capacity data were measured between 340-1000 K with a differential scanning calorimeter. The high-temperature data were combined with the 290-350 K adiabatic values, extrapolated to 1700 K, and integrated to yield the following entropy equation for end-member monticellite (298-1700 K): ST0(J ?? mol-1 K-1) = S2980 + 164.79 In T + 15.337 ?? 10-3 T + 22.791 ?? 105 T-2 - 968.94. Phase equilibria in the CaO-MgO-SiO2 system were calculated from 973 to 1673 K and 0 to 12 kbar with these new data combined with existing data for akermanite (Ak), diopside (Di), forsterite (Fo), merwinite (Me) and wollastonite (Wo). The location of the calculated reactions involving the phases Mo and Fo is affected by their mutual solid solution. A best fit of the thermodynamically generated curves to all experiments is made when the S0298 of Me is 250.2 J ?? mol-1 K-1 less than the measured value of 253.2 J ?? mol-1 K-1. A best fit to the reversals for the solid-solid and decarbonation reactions in the CaO-MgO-SiO2-CO2 system was obtained with the ??G0298 (kJ ?? mole-1) for the phases Ak(-3667), Di(-3025), Fo(-2051), Me(-4317) and Mo(-2133). The two invariant points - Wo and -Fo for the solid-solid reactions are located at 1008 ?? 5 K and 6.3 ?? 0.1 kbar, and 1361 ?? 10 K and 10.2 ?? 0.2 kbar respectively. The location of the thermodynamically generated curves is in excellent agreement with most experimental data on decarbonation equilibria involving these phases. ?? 1986.

Random-lattice models and simulation algorithms for the phase equilibria in two-dimensional condensed systems of particles with coupled internal and translational degrees of freedom

DEFF Research Database (Denmark)

Nielsen, Morten; Miao, Ling; Ipsen, John Hjorth

1996-01-01

In this work we concentrate on phase equilibria in two-dimensional condensed systems of particles where both translational and internal degrees of freedom are present and coupled through microscopic interactions, with a focus on the manner of the macroscopic coupling between the two types...... where the spin degrees of freedom are slaved by the translational degrees of freedom and develop a first-order singularity in the order-disorder transition that accompanies the lattice-melting transition. The internal degeneracy of the spin states in model III implies that the spin order...

A unifying approach to existence of Nash equilibria

NARCIS (Netherlands)

Balder, E.J.

1997-01-01

An approach initiated in [4] is shown to unify results about the existence of (i) Nash equilibria in games with at most countably many players, (ii) Cournot-Nash equilibrium distributions for large, anonymous games, and (iii) Nash equilibria (both mixed and pure) for continuum games. A new, central

Two-fluid equilibria with flow

International Nuclear Information System (INIS)

Steinhauer, L.

1999-01-01

The formalism is developed for flowing two-fluid equilibria. The equilibrium system is governed by a pair of second order partial differential equations for the magnetic stream function and the ion stream function plus a Bernoulli-like equation for the density. There are six arbitrary surface function. There are separate characteristic surfaces for each species, which are the guiding-center surfaces. This system is a generalization of the familiar Grad-Shafranov system for a single-fluid equilibrium without flow, which has only one equation and two arbitrary surface functions. In the case of minimum energy equilibria, the six surface functions take on particular forms. (author)

The Pierce diode with an external circuit: II, Non-uniform equilibria

International Nuclear Information System (INIS)

Lawson, W.S.

1987-01-01

The non-uniform (non-linear) equilibria of the classical (short circuit) Pierce diode and the extended (series RLC external circuit) Pierce diode are described theoretically, and explored via computer simulation. It is found that most equilibria are correctly predicted by theory, but that the continuous set of equilibria of the classical Pierce diode at α = 2π are not observed. The stability characteristics of the non-uniform equilibria are also worked out, and are consistent with the simulations. 8 refs., 22 figs., 3 tabs

Ideal MHD stability of high poloidal beta equilibria in TFTR

International Nuclear Information System (INIS)

Sabbagh, S.A.; Mauel, M.E.; Navratil, G.A.; Bell, M.G.; Budny, R.V.; Chance, M.S.; Fredrickson, E.D.; Jardin, S.C.; Manickam, J.; McCune, D.C.; McGuire, K.M.; Wieland, R.M.; Zarnstorff, M.C.; Phillips, M.W.; Hughes, M.H.; Kesner, J.

1991-01-01

Recent experiments in TFTR have expanded the operating space of the device to include plasmas with values of var-epsilon β p dia ≡ 2μ 0 var-epsilon perpendicular >/ p >> 2 as large as 1.6, and Troyon normalized diamagnetic beta β N dia ≡ β t perpendicular aB t /10 -8 I p as large as 4.7. At values of var-epsilon β p dia ≥ 1.3, a separatrix was observed to enter the vacuum vessel, producing a naturally diverted discharge. Plasmas with large values of var-epsilon β p dia were created with both the plasma current, I p , held constant and with I p decreased, or ramped down, before the start of neutral beam injection. A convenient characterization of the change in I p using experimental parameters can be defined by the ratio of I p before the ramp down, to I p during the neutral beam heating phase, F I p . The ideal MHD stability of these equilibria is investigated to determine their location in stability space, and to study the role of plasma current and pressure profile modification in the creation of these high var-epsilon β p and β N plasmas. The evolution of these plasmas is modelled from experimental data using the TRANSP code. Two-dimensional equilibria are computed from the TRANSP results and used as input to both high and low-n stability codes including PEST. The high var-epsilon β p equilibria, which generally have an oblate cross-sectional shape, are in the first stability region to high-n ballooning modes. At constant I p , these equilibria generally have maximum pressure gradients near the magnetic axis and are stable to n=1 modes without a stabilizing conducting wall. The effect of the current profile shape on the stability of low-n kink/ballooning modes and the requirements for these plasmas to access the second stability region are examined. 6 refs

Evaluation of a Mathematical Model for Single Component Adsorption Equilibria with Reference to the Prediction of Multicomponent Adsorption Equilibria

DEFF Research Database (Denmark)

Krøll, Annette Elisabeth; Marcussen, Lis

1997-01-01

An equilibrium equation for pure component adsorption is compared to experiments and to the vacancy solution theory. The investigated equilibrium equation is a special case of a model for prediction of multicomponent adsorption equilibria.The vacancy solution theory for multicomponent systems...... requires binary experimental data for determining the interaction parameters of the Wilson equation; thus a large number of experiments are needed. The multicomponent equilibria model which is investigated for single component systems in this work is based on pure component data only. This means...... that the requirement for experimental data is reduced significantly.The two adsorption models are compared, using experimental pure gas adsorption data found in literature. The results obtained by the models are in close agreement for pure component equilibria and they give a good description of the experimental data...

Shallow-water vortex equilibria and their stability

Energy Technology Data Exchange (ETDEWEB)

Plotka, H; Dritschel, D G, E-mail: hanna@mcs.st-andrews.ac.uk, E-mail: dgd@mcs.st-andrews.ac.uk [School of Mathematics and Statistics, University of St Andrews, North Haugh, St. Andrews KY16 9SS (United Kingdom)

2011-12-22

We first describe the equilibrium form and stability of steadily-rotating simply-connected vortex patches in the single-layer quasi-geostrophic model of geophysical fluid dynamics. This model, valid for rotating shallow-water flow in the limit of small Rossby and Froude numbers, has an intrinsic length scale L{sub D} called the 'Rossby deformation length' relating the strength of stratification to that of the background rotation rate. Specifically, L{sub D} = c/f where c={radical}gH is a characteristic gravity-wave speed, g is gravity (or 'reduced' gravity in a two-layer context where one layer is infinitely deep), H is the mean active layer depth, and f is the Coriolis frequency (here constant). We next introduce ageostrophic effects by using the full shallow-water model to generate what we call 'quasi-equilibria'. These equilibria are not strictly steady, but radiate such weak gravity waves that they are steady for all practical purposes. Through an artificial ramping procedure, we ramp up the potential vorticity anomaly of the fluid particles in our quasi-geostrophic equilibria to obtain shallow-water quasi-equilibria at finite Rossby number. We show a few examples of these states in this paper.

Experimental study and modelling of competitive adsorption equilibria of aromatics in liquid phase on X and Y faujasites; Etude experimentale et modelisation des equilibres d'adsorption competitive d'aromatiques en phase liquide sur des faujasites X et Y

Energy Technology Data Exchange (ETDEWEB)

Tournier, H.

2000-10-13

The separation of p-xylene from C{sub 8} aromatics is performed industrially by selective adsorption on zeolitic molecular sieves. The aim of this work is to study and model adsorption equilibria of C{sub 8} and C{sub 10} aromatics on X and Y zeolites. The experimental data are obtained by an entirely automated equipment allowing to work in a large range of temperature (50 deg. C - 250 deg. C). With this equipment, we can follow the evolution of the composition of the liquid phase and determine the composition of the adsorbed phase at equilibrium by a mass balance calculation and with an inert component. Two analytical techniques are used to determine the composition of the liquid phase: (1) a classical method using a gas chromatograph (GC) allowed to measure selectivities in the concentration range (3%-97%) in a component; (2) an original method based on the use and on the measure of {sup 13}C labelled xylenes was developed to investigate the ranges of strongly contrasting concentrations [0-3%] and [97%-100%] in a component, which are representative of high purity domains. Lastly, three thermodynamic models are used to describe the adsorption equilibria: the Langmuir-Freundlich model, the quasi-chemical model and the statistical model. The last model is the more interesting, because it is based on physical considerations. A new statistical model has been developed with taking into account some observations coming from adsorption phenomenon in zeolites. (author)

Collisionless current sheet equilibria

Science.gov (United States)

Neukirch, T.; Wilson, F.; Allanson, O.

2018-01-01

Current sheets are important for the structure and dynamics of many plasma systems. In space and astrophysical plasmas they play a crucial role in activity processes, for example by facilitating the release of magnetic energy via processes such as magnetic reconnection. In this contribution we will focus on collisionless plasma systems. A sensible first step in any investigation of physical processes involving current sheets is to find appropriate equilibrium solutions. The theory of collisionless plasma equilibria is well established, but over the past few years there has been a renewed interest in finding equilibrium distribution functions for collisionless current sheets with particular properties, for example for cases where the current density is parallel to the magnetic field (force-free current sheets). This interest is due to a combination of scientific curiosity and potential applications to space and astrophysical plasmas. In this paper we will give an overview of some of the recent developments, discuss their potential applications and address a number of open questions.

Behavior of magnetic islands in 3D MHD equilibria of helical devices

International Nuclear Information System (INIS)

Hayashi, T.; Sato, T.; Nakajima, N.

1994-09-01

Magnetic island formation in three-dimensional finite-β equilibria in the H-1 Heliac is studied by using the HINT code. It is found that the size of a dangerous island should increase with β but that a destruction of the equilibrium at low β is avoided because the rotational transform evolves to exclude the rational surface concerned. At higher β there is evidence of near-resonant flux surface deformations which may lead to an equilibrium limit. A reconnected equilibrium at still higher β exhibits a double island structure which is similar to homoclinic phase portraits which have been observed after separatrix reconnection in Hamiltonian systems. Physical mechanism of the island formation in finite-β helical equilibria is investigated to confirm there are cases where the global effect of the Pfirsch-Schlueter currents is important. The earlier theory is extended to elucidate the occurence of the complete self-healing of island when the resistive interchange criterion satisfied. (author)

Two-dimensional magnetohydrodynamic equilibria with flow and studies of equilibria fluctuations

International Nuclear Information System (INIS)

Agim, Y.Z.

1989-08-01

A set of reduced ideal MHD equations is derived to investigate equilibria of plasmas with mass flow in general two-dimensional geometry. These equations provide a means of investigating the effects of flow on self-consistent equilibria in a number of new two-dimensional configurations such as helically symmetric configurations with helical axis, which are relevant to stellarators, as well as axisymmetric configurations. It is found that as in the axisymmetric case, general two-dimensional flow equilibria are governed by a second-order quasi-linear partial differential equation for a magnetic flux function, which is coupled to a Bernoulli-type equation for the density. The equation for the magnetic flux function becomes hyperbolic at certain critical flow speeds which follow from its characteristic equation. When the equation is hyperbolic, shock phenomena may exist. As a particular example, unidirectional flow along the lines of symmetry is considered. In this case, the equation mentioned above is always elliptic. An exact solution for the case of helically symmetric unidirectional flow is found and studied to determine flow effects on the magnetic topology. In second part of this thesis, magnetic fluctuations due to the thermally excited MHD waves are investigated using fluid and kinetic models to describe stable, uniform, compressible plasma in the range above the drift wave frequency and below the ion cyclotron frequency. It is shown that the fluid model with resistivity yields spectral densities which are roughly Lorentzian, exhibit equipartition with no apparent cutoff in wavenumber space and a Bohm-type diffusion coefficient. Under certain conditions, the ensuing transport may be comparable to classical values. For a phenomenological cutoff imposed on the spectrum, the typical fluctuating-to-equilibrium magnetic field ratio is found to be of the order of 10 -10

On tokamak equilibria with a zero current or negative current central region

International Nuclear Information System (INIS)

Chu, M.S.; Parks, P.B.

2002-01-01

Several tokamak experiments have reported the development of a central region with vanishing currents (the current hole). The straightforward application of results from the work of Greene, Johnson and Weimer [Phys. Fluids 14, 671 (1971)] on a tokamak equilibrium to these plasmas leads to the apparent singularities in several physical quantities including the Shafranov shift and casts doubts on the existence of this type of equilibria. In this paper, the above quoted equilibrium theory is re-examined and extended to include equilibria with a current hole. It is shown that singularities can be circumvented and that equilibria with a central current hole do satisfy the magnetohydrodynamic equilibrium condition with regular behavior for all the physical quantities and do not lead to infinitely large Shafranov shifts. Isolated equilibria with negative current in the central region could exist. But equilibria with negative currents in general do not have neighboring equilibria and thus cannot have experimental realization, i.e., no negative currents can be driven in the central region

The Pierce diode with an external circuit. I. Oscillations about nonuniform equilibria

International Nuclear Information System (INIS)

Lawson, W.S.

1989-01-01

The nonuniform (nonlinear) equilibria of the classical (short circuit) Pierce diode and the extended (series RLC external circuit) Pierce diode are described, and the spectrum of oscillations (stable and unstable) about these equilibria are worked out. It is found that only the external capacitance alters the equilibria, though all elements alter the spectrum. In particular, the introduction of an external capacitor destabilizes some equilibria that are marginally stable without the capacitor. Computer simulations are performed to test the theoretical predictions for the case of an external capacitor only. It is found that most equilibria are correctly predicted by theory, but that the continuous set of equilibria of the classical Pierce diode at Pierce parameters (α=ω/sub pL//v 0 ) that are multiples of 2π are not observed. This appears to be a failure of the simulation method under the rather singular conditions rather than a failure of the theory

Nematic Equilibria on a Two-Dimensional Annulus

KAUST Repository

Lewis, A. H.; Aarts, D. G. A. L.; Howell, P. D.; Majumdar, A.

2017-01-01

We study planar nematic equilibria on a two-dimensional annulus with strong and weak tangent anchoring, in the Oseen–Frank theoretical framework. We analyze a radially invariant defect-free state and compute analytic stability criteria for this state in terms of the elastic anisotropy, annular aspect ratio, and anchoring strength. In the strong anchoring case, we define and characterize a new spiral-like equilibrium which emerges as the defect-free state loses stability. In the weak anchoring case, we compute stability diagrams that quantify the response of the defect-free state to radial and azimuthal perturbations. We study sector equilibria on sectors of an annulus, including the effects of weak anchoring and elastic anisotropy, giving novel insights into the correlation between preferred numbers of boundary defects and the geometry. We numerically demonstrate that these sector configurations can approximate experimentally observed equilibria with boundary defects.

Nematic Equilibria on a Two-Dimensional Annulus

KAUST Repository

Lewis, A. H.

2017-01-16

We study planar nematic equilibria on a two-dimensional annulus with strong and weak tangent anchoring, in the Oseen–Frank theoretical framework. We analyze a radially invariant defect-free state and compute analytic stability criteria for this state in terms of the elastic anisotropy, annular aspect ratio, and anchoring strength. In the strong anchoring case, we define and characterize a new spiral-like equilibrium which emerges as the defect-free state loses stability. In the weak anchoring case, we compute stability diagrams that quantify the response of the defect-free state to radial and azimuthal perturbations. We study sector equilibria on sectors of an annulus, including the effects of weak anchoring and elastic anisotropy, giving novel insights into the correlation between preferred numbers of boundary defects and the geometry. We numerically demonstrate that these sector configurations can approximate experimentally observed equilibria with boundary defects.

Numerical calculation of axisymmetric non-neutral plasma equilibria

International Nuclear Information System (INIS)

Spencer, R.L.; Rasband, S.N.; Vanfleet, R.R.

1993-01-01

Efficient techniques for computing axisymmetric non-neutral plasma equilibria are described. These equilibria may be obtained either by requiring global thermal equilibrium, by specifying the midplane radial density profile, or by specifying the radial profile of ∫n dz. Both splines and finite-differences are used, and the accuracy of the two is compared by using a new characterization of the thermal equilibrium density profile which gives a simple formula for estimating the radial and axial gradient scale lengths of thermal equilibria. It is found that for global thermal equilibrium 1% accuracy is achieved with splines if the distance between neighboring splines is about two Debye lengths while finite differences require a grid spacing of about one-half Debye length to achieve the same accuracy

Experimental vapor-liquid equilibria data for binary mixtures of xylene isomers

Directory of Open Access Journals (Sweden)

W.L. Rodrigues

2005-09-01

Full Text Available Separation of aromatic C8 compounds by distillation is a difficult task due to the low relative volatilities of the compounds and to the high degree of purity required of the final commercial products. For rigorous simulation and optimization of this separation, the use of a model capable of describing vapor-liquid equilibria accurately is necessary. Nevertheless, experimental data are not available for all binaries at atmospheric pressure. Vapor-liquid equilibria data for binary mixtures were isobarically obtained with a modified Fischer cell at 100.65 kPa. The vapor and liquid phase compositions were analyzed with a gas chromatograph. The methodology was initially tested for cyclo-hexane+n-heptane data; results obtained are similar to other data in the literature. Data for xylene binary mixtures were then obtained, and after testing, were considered to be thermodynamically consistent. Experimental data were regressed with Aspen Plus® 10.1 and binary interaction parameters were reported for the most frequently used activity coefficient models and for the classic mixing rules of two cubic equations of state.

(Liquid + liquid) equilibria of four alcohol–water systems containing 1,8-cineole at T = 298.15 K

International Nuclear Information System (INIS)

Li, Hengde; Feng, Zhangni; Wan, Li; Huang, Cheng; Zhang, Tianfei; Fang, Yanxiong

2016-01-01

Graphical abstract: (Liquid + liquid) equilibria of C_1–C_4 alcohol–water systems containing 1,8-cineole are presented. Distribution ratios of alcohol in the mixtures are examined. The immiscible region of the LLE systems is evaluated and discussed. - Highlights: • Ternary (liquid + liquid) equilibria containing 1,8-cineole are presented. • Distribution ratios of C_1–C_4 alcohol in the mixtures are examined. • The LLE values were correlated using the NRTL and UNIQUAC models. - Abstract: As an eco-friendly compound from essential oils, 1,8-cineole (cineole, eucalyptol) has the potential to replace the ozone depleting industrial solvents. This paper presents experimental (liquid + liquid) equilibrium (LLE) data for four alcohol–water systems containing 1,8-cineole. To evaluate the phase equilibrium properties of 1,8-cineole in aqueous alcohol mixtures, LLE values for the ternary systems (water + methanol or ethanol or 1-propanol or 1-butanol + 1,8-cineole) were determined with a tie-line method at T = 298.15 K under atmospheric pressure. The well-known Hand, Bachman and Othmer–Tobias equations were used to test the reliability of the experimental results. The binodal curves and distribution ratios of alcohol in the mixtures are shown and discussed. The experimental LLE values were satisfactorily correlated by the NRTL and UNIQUAC models.

Dynamic data evaluation for solid-liquid equilibria

DEFF Research Database (Denmark)

Cunico, Larissa; Ceriani, Roberta; Kang, Jeong Won

The accuracy and reliability of the measured data sets to be used in regression of model parameters is an important issue related to modeling of phase equilibria. It is clear that good parameters for any model cannot be obtained from low quality data. A thermodynamic consistency test for solid...... and parameter regression. The paper will highlight the data collection, the data analysis for SLE data and the thermodynamic model performance (such as NRTL, UNIQUAC and original UNIFAC)....... studies considering the methodology proposed for SLE thermodynamic consistency tests and data from open literature and databases such as NIST-TDE®, DIPPR® and DECHEMA® are presented. The SLE consistency test and data evaluation is performed in a software containing option for data analysis, model analysis...

Phase equilibria and crystal chemistry in the ternary system BaO-TiO 2-Nb 2O 5. II. New barium polytitanates with <5 mole% Nb 2O 5

Science.gov (United States)

Roth, R. S.; Ettlinger, L. D.; Parker, H. S.

1987-06-01

Four new compounds were found in the BaO-TiO 2-Nb 2O 5 system, each containing orth ≈ 9.9A˚, b mon ≈ a orth ≈ 17A˚). Ba 14Ti 40Nb 2O 99 is a 20-layer orthorhombic phase, Cmc*, withc ≈ 46.86A˚. Ba 10Ti 28Nb 2O 72 is a 7-layer monoclinic phase, C2m, c ≈ 16.72A˚, β ≈ 101.2°. Ba 18Ti 54Nb 2O 132 is a 13-layer monoclinic phase, C2m, c ≈ 30.65A˚, β ≈ 96°. The compositions were derived by analogy to the layers in Ba 4Ti 13 O 30 and Ba 6Ti 17O 40 and are consistent with limited phase equilibria data.

Comparison of two association models (Elliott-Suresh-Donohue and simplified PC-SAFT) for complex phase equilibria of hydrocarbon-water and amine-containing mixtures

DEFF Research Database (Denmark)

Grenner, Andreas; Schmelzer, Jürgen; von Solms, Nicolas

2006-01-01

, and water. Furthermore, the predictive capabilities of the models are investigated for four ternary systems composed of these components, which exhibit complex liquid-liquid(-liquid) equilibria (LLLE). Various aspects of association models which have an influence in the results are studied for the PC......, both models perform overall similarly for the binary systems, although ESD shows a remarkably good behavior despite its simplicity and the use of only the two-site scheme for all associating compounds. The prediction of the LLE in the ternary systems water + octane + aniline and water + CHA + aniline......Two Wertheim-based association models, the simplified PC-SAFT and the Elliott-Suresh-Donohue (ESD) equation of state, are compared in this work for the description of vapor-liquid equilibria (VLE) and liquid-liquid equilibria (LLE) in binary systems of aniline, cyclohexylamine (CHA), hydrocarbons...

Phase formation in the Li2MoO4-Rb2MoO4-Ln2(MoO4)3 systems and the properties of LiRbLn2(MoO4)4

International Nuclear Information System (INIS)

Basovich, O.M.; Khajkina, E.G.; Vasil'ev, E.V.; Frolov, A.M.

1995-01-01

Phase equilibria within subsolidus range of ternary salt systems Li 2 MoO 4 -Rb 2 MoO 4 -Ln 2 (MoO 4 ) 4 (Ln - Nd, Er) are analyzed. Formation of ternary molybdate LiRbNd 2 (MoO 4 ) 4 is proved along LiNd(MoO 4 ) 2 -RbNd(MoO 4 )-2 cross-section. Phase diagram of this cross-section is plotted. Similar compounds are synthesized for Ln = La-Eu. The parameters of their monoclinic elementary cells are determined. Luminescent properties of LiRbLa 2 (MoO 4 ) 4 -Nd 3+ are studied. 17 refs., 4 figs., 2 tabs

Edge stability and pedestal profile sensitivity of snowflake diverted equilibria in the TCV Tokamak

International Nuclear Information System (INIS)

Medvedev, S.Yu.; Ivanov, A.A.; Martynov, A.A.; Poshekhonov, Yu.Yu.; Behn, R.; Martin, Y.R.; Moret, J.M.; Piras, F.; Pitzschke, A.; Pochelon, A.; Sauter, O.; Villard, L.

2010-01-01

A second order null divertor (snowflake) has been successfully created and controlled in the TCV tokamak[1] (F. Piras et al., Plasma Phys. Control. Fusion, 2009). The results of ideal MHD edge stability computations show an enhancement of the edge stability properties of the snowflake equilibria compared to standard x-point configurations[2] (S. Yu. Medvedev et al., 36th EPS Conference on Plasma Physics, 2009). However, a sensitivity study of the stability limits to variations of the pedestal profiles is essential for making conclusions about possibilities of ELM control in snowflake plasmas. Variations of the edge stability and beta limits for several types of snowflake equilibria, different values of triangularity and various pedestal profiles are investigated (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Phase Equilibria of the Ternary Sn-Pb-Co System at 250°C and Interfacial Reactions of Co with Sn-Pb Alloys

Science.gov (United States)

Wang, Chao-hong; Kuo, Chun-yi; Yang, Nian-cih

2015-11-01

The isothermal section of the ternary Sn-Pb-Co system at 250°C was experimentally determined through a series of the equilibrated Sn-Pb-Co alloys of various compositions. The equilibrium phases were identified on the basis of compositional analysis. For the Sn-Co intermetallic compounds (IMCs), CoSn3, CoSn2, CoSn and Co3Sn2, the Pb solubility was very limited. There exist five tie-triangle regions. The Co-Pb system involves one monotectic reaction, so the phase separation of liquid alloys near the Co-Pb side occurred prior to solidification. The immiscibility field was also determined. Additionally, interfacial reactions between Co and Sn-Pb alloys were conducted. The reaction phase for the Sn-48 at.%Pb and Sn-58 at.%Pb at 250°C was CoSn3 and CoSn2, respectively. Both of them were simultaneously formed in the Sn-53 at.%Pb/Co. The formed IMCs were closely associated to the phase equilibria relationship of the liquid-CoSn3-CoSn2 tie-triangle. Furthermore, with increasing temperatures, the phase formed in equilibrium with Sn-37 wt.%Pb was found to transit from CoSn3 to CoSn2 at 275°C. We propose a simple method of examining the phase transition temperature in the interfacial reactions to determine the boundaries of the liquid-CoSn3-CoSn2 tie-triangles at different temperatures.

Stable and metastable equilibria in PbSe + SnI2=SnSe + PbI2

International Nuclear Information System (INIS)

Odin, I.N.; Grin'ko, V.V.; Kozlovskij, V.F.; Demidova, E.D.

2003-01-01

T-x-y phase diagrams of the PbSe + SnI 2 =SnSe + PbI 2 mutual system (stable states) are plotted for the first time. It is shown that melt, solid solutions on the base of components of the mutual system and phase on the base of Sn 2 SeI 4 take part in phase equilibria. Transformations in the PbSe + SnI 2 =SnSe + PbI 2 mutual system leading to crystallization of metastable polytype modifications of lead iodides and metastable ternary compound forming in PbSe-PbI 2 system are investigated for the first time [ru

Stability and attractive basins of multiple equilibria in delayed two-neuron networks

International Nuclear Information System (INIS)

Huang Yu-Jiao; Zhang Hua-Guang; Wang Zhan-Shan

2012-01-01

Multiple stability for two-dimensional delayed recurrent neural networks with piecewise linear activation functions of 2r (r ≥ 1) corner points is studied. Sufficient conditions are established for checking the existence of (2r + 1) 2 equilibria in delayed recurrent neural networks. Under these conditions, (r + 1) 2 equilibria are locally exponentially stable, and (2r + 1) 2 — (r + 1) 2 — r 2 equilibria are unstable. Attractive basins of stable equilibria are estimated, which are larger than invariant sets derived by decomposing state space. One example is provided to illustrate the effectiveness of our results. (general)

Stability of nonlinear Vlasov-Poisson equilibria through spectral deformation and Fourier-Hermite expansion.

Science.gov (United States)

Siminos, Evangelos; Bénisti, Didier; Gremillet, Laurent

2011-05-01

We study the stability of spatially periodic, nonlinear Vlasov-Poisson equilibria as an eigenproblem in a Fourier-Hermite basis (in the space and velocity variables, respectively) of finite dimension, N. When the advection term in the Vlasov equation is dominant, the convergence with N of the eigenvalues is rather slow, limiting the applicability of the method. We use the method of spectral deformation introduced by Crawford and Hislop [Ann. Phys. (NY) 189, 265 (1989)] to selectively damp the continuum of neutral modes associated with the advection term, thus accelerating convergence. We validate and benchmark the performance of our method by reproducing the kinetic dispersion relation results for linear (spatially homogeneous) equilibria. Finally, we study the stability of a periodic Bernstein-Greene-Kruskal mode with multiple phase-space vortices, compare our results with numerical simulations of the Vlasov-Poisson system, and show that the initial unstable equilibrium may evolve to different asymptotic states depending on the way it was perturbed. © 2011 American Physical Society

High-pressure anatectic paragneisses from the Namche Barwa, Eastern Himalayan Syntaxis: Textural evidence for partial melting, phase equilibria modeling and tectonic implications

Science.gov (United States)

Guilmette, C.; Indares, A.; Hébert, R.

2011-05-01

Rare kyanite-bearing anatectic paragneisses are found as boudins within sillimanite-bearing paragneisses of the core of the Namche Barwa Antiform, Tibet. In the present study, we document an occurrence from the NW side of the Yarlung Zangbo River. These rocks mainly consist of the assemblage garnet + K-feldspar + kyanite ± biotite + quartz + rutile ± plagioclase with kyanite locally pseudomorphed by sillimanite. The documented textures are consistent with the rocks having undergone biotite-dehydration melting in the kyanite stability field, under high-P granulite facies conditions, and having experienced melt extraction. However textures related to melt crystallization are ubiquitous both in polymineralic inclusions in garnet and in the matrix, suggesting that a melt fraction had remained in these rocks. Phase equilibria modelling was undertaken in the NCKFMASTHO system with THERMOCALC. P-T pseudosections built with the bulk compositions of one aluminous and one sub-aluminous paragneiss samples predict a biotite-kyanite-garnet-quartz-plagioclase-K-feldspar-liquid-rutile ± ilmenite field, in which biotite-dehydration melting occurs, located in the P-T range of ~ 800-875 °C and ~ 10-17 kbar. In addition, the topologies of these pseudosections are consistent with substantial melt loss during prograde metamorphism. A second set of P-T pseudosections with melt-reintegrated model bulk compositions were thus constructed to evaluate the effect of melt loss. The integration of textural information, precise mineral modes, mineral chemistry, and phase equilibria modelling allowed to constrain a P-T path where the rocks are buried to lower crustal depths at peak P-T conditions higher than 14 kbar and 825 °C, possibly in the order of 15-16 kbar and 850 °C, followed by decompression and cooling to P-T conditions of around 9 kbar and 810 °C, under which the remaining melt was solidified. The implications for granite production at the NBA and for Himalayan tectonic models

The impact of uni-univalent electrolytes on (water + acetic acid + toluene) equilibria: Representation with electrolyte-NRTL model

International Nuclear Information System (INIS)

Saien, Javad; Fattahi, Mahdi; Mozafarvandi, Maryam

2014-01-01

Highlights: • Experimental LLE data for water + acetic acid + toluene + NaCl or KCl were reported. • The salting-out effect was detected; indicating the stronger effect of NaCl. • The electrolyte-NRTL model was adequately used to correlate the phase equilibria. • A good agreement was observed between calculated and experimental tie-lines. - Abstract: The presence of salts can significantly alter the (liquid + liquid) equilibrium and extraction process. In this work, a study was conducted on the (liquid + liquid) equilibria of (water + acetic acid + toluene + sodium chloride or potassium chloride) at temperatures (288.2, 298.2 and 313.2) K. This chemical system, irrespective of salt, is frequently used in (liquid + liquid) extraction investigations. The selected salt concentrations in initial aqueous solutions were (0.9 and 1.7) mol · L −1 . The results show that salting-out effect of the salts was significant, so that an enhancement in the acetic acid distribution coefficient was achieved within (15.6 to 66.8)% with NaCl and within (2.5 to 37.6)% with KCl. Meantime, high separation factors were found at low temperatures and low solute concentrations. The electrolyte-NRTL model was satisfactorily used to correlate the phase equilibria. In this regard for each salt, the temperature dependent binary interaction parameters between components were calculated. The predicted tie-line mole fractions give root-mean square deviation (RMSD) values of only 0.0038 and 0.0045 for the systems containing NaCl and KCl, respectively

Computation of Stackelberg Equilibria of Finite Sequential Games

DEFF Research Database (Denmark)

Bosanski, Branislav; Branzei, Simina; Hansen, Kristoffer Arnsfelt

2015-01-01

The Stackelberg equilibrium is a solution concept that describes optimal strategies to commit to: Player~1 (the leader) first commits to a strategy that is publicly announced, then Player~2 (the follower) plays a best response to the leader's choice. We study Stackelberg equilibria in finite...... sequential (i.e., extensive-form) games and provide new exact algorithms, approximate algorithms, and hardness results for finding equilibria for several classes of such two-player games....

On phase equilibria in duplex stainless steels

Energy Technology Data Exchange (ETDEWEB)

Wessman, S. [Swerea KIMAB AB, Stockholm (Sweden); Pettersson, R. [Outokumpu Stainless AB, Avesta Research Centre, Avesta (Sweden); Hertzman, S. [Outokumpu Stainless Research Foundation, Stockholm (Sweden)

2010-05-15

The equilibrium conditions of four duplex stainless steels; Fe-23Cr-4.5Ni-0.1N, Fe-22Cr-5.5Ni-3Mo-0.17N, Fe-25Cr-7Ni-4Mo-0.27N and Fe-25Cr-7Ni-4Mo-1W-1.5Cu-0.27N were studied in the temperature region from 700 to 1000 C. Phase compositions were determined with SEM EDS and the phase fractions using image analysis on backscattered SEM images. The results showed that below 1000 C the steels develop an inverse duplex structure with austenite and sigma phase, of which the former is the matrix phase. With decreasing temperature, the microstructure will be more and more complex and finely dispersed. The ferrite is, for the higher alloyed steels, only stable above 1000 C and at lower temperatures disappears in favour of intermetallic phases. The major intermetallic phase is sigma phase with small amounts of chi phase, the latter primarily in high Mo and W grades. Nitrides, not a focus in this investigation, were present as rounded particles and acicular precipitates at lower temperatures. The results were compared to theoretical predictions using the TCFE5 and TCFE6 databases. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Surfactant Membrane Phases Containing Mixtures of Hydrocarbon and Fluorocarbon Surfactants

International Nuclear Information System (INIS)

de Campo, Liliana; Warr, G.G.

2005-01-01

Full text: We describe the structure and stability of sponge and lamellar phases comprising mixtures of hydrocarbon and fluorocarbon surfactants. Such mixtures can show limited miscibility with each other, forming for example coexisting populations of hydrocarbon rich and fluorocarbon rich micelles under some circumstances. Our system is based on the well-characterised lamellar and sponge phases of cetylpyridinium chloride, hexanol and 0.2M brine, into which the partially fluorinated surfactant N-1H,1H,2H,2H-tridecafluorooctylpyridinium chloride is incorporated. By probing the structures with SAXS (small angle x-ray scattering) and SANS (small angle neutron scattering) using contrast variation, and by characterizing the dynamic properties with dynamic light scattering, we will describe the effect of incorporating the fluorinated surfactant on the phase equilibria and properties of the surfactant membrane structures. (authors)

On Pure and (approximate) Strong Equilibria of Facility Location Games

DEFF Research Database (Denmark)

Hansen, Thomas Dueholm; Telelis, Orestis A.

2008-01-01

We study social cost losses in Facility Location games, where n selfish agents install facilities over a network and connect to them, so as to forward their local demand (expressed by a non-negative weight per agent). Agents using the same facility share fairly its installation cost, but every...... agent pays individually a (weighted) connection cost to the chosen location. We study the Price of Stability (PoS) of pure Nash equilibria and the Price of Anarchy of strong equilibria (SPoA), that generalize pure equilibria by being resilient to coalitional deviations. For unweighted agents on metric...

Theory of phase equilibria and critical mixing points in binary lipid bilayers

DEFF Research Database (Denmark)

Risbo, Jens; Sperotto, Maria Maddalena; Mouritsen, Ole G.

1995-01-01

the transition is discussed in terms of the molecular properties of the lipid acyl chains. The results of the numerical model study are expected to have consequences for the interpretation of experimental measurements on lipid bilayer systems in terms of phase diagrams. (C) 1995 American Institute of Physics....

Helically symmetric equilibria with pressure anisotropy and incompressible plasma flow

Science.gov (United States)

Evangelias, A.; Kuiroukidis, A.; Throumoulopoulos, G. N.

2018-02-01

We derive a generalized Grad-Shafranov equation governing helically symmetric equilibria with pressure anisotropy and incompressible flow of arbitrary direction. Through the most general linearizing ansatz for the various free surface functions involved therein, we construct equilibrium solutions and study their properties. It turns out that pressure anisotropy can act either paramegnetically or diamagnetically, the parallel flow has a paramagnetic effect, while the non-parallel component of the flow associated with the electric field has a diamagnetic one. Also, pressure anisotropy and flow affect noticeably the helical current density.

Numerical computation of FCT equilibria by inverse equilibrium method

International Nuclear Information System (INIS)

Tokuda, Shinji; Tsunematsu, Toshihide; Takeda, Tatsuoki

1986-11-01

FCT (Flux Conserving Tokamak) equilibria were obtained numerically by the inverse equilibrium method. The high-beta tokamak ordering was used to get the explicit boundary conditions for FCT equilibria. The partial differential equation was reduced to the simultaneous quasi-linear ordinary differential equations by using the moment method. The regularity conditions for solutions at the singular point of the equations can be expressed correctly by this reduction and the problem to be solved becomes a tractable boundary value problem on the quasi-linear ordinary differential equations. This boundary value problem was solved by the method of quasi-linearization, one of the shooting methods. Test calculations show that this method provides high-beta tokamak equilibria with sufficiently high accuracy for MHD stability analysis. (author)

Phase equilibria, crystal chemistry, electronic structure and physical properties of Ag-Ba-Ge clathrates

Energy Technology Data Exchange (ETDEWEB)

Zeiringer, I.; Chen Mingxing [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Bednar, I.; Royanian, E.; Bauer, E. [Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Wien (Austria); Podloucky, R.; Grytsiv, A. [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Rogl, P., E-mail: peter.franz.rogl@univie.ac.at [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Effenberger, H. [Institute of Mineralogy and Crystallography, University of Vienna, A-1090 Wien (Austria)

2011-04-15

In the Ag-Ba-Ge system the clathrate type-{Iota} solid solution, Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y}, extends at 800 deg. C from binary Ba{sub 8}Ge{sub 43{open_square}3} ({open_square} is a vacancy) to Ba{sub 8}Ag{sub 5.3}Ge{sub 40.7}. For the clathrate phase (1 {<=} x {<=} 5.3) the cubic space group Pm3-bar n was established by X-ray powder diffraction and confirmed by X-ray single-crystal analyses of the samples Ba{sub 8}Ag{sub 2.3}Ge{sub 41.9{open_square}1.8} and Ba{sub 8}Ag{sub 4.4}Ge{sub 41.3{open_square}0.3}. Increasing the concentration of Ag causes the lattice parameters of the solid solution to increase linearly from a value of a = 1.0656 (x = 0, y = 3) to a = 1.0842 (x = 4.8, y = 0) nm. Site preference determination using X-ray refinement reveals that Ag atoms preferentially occupy the 6d site randomly mixed with Ge and vacancies, which become filled in the compound Ba{sub 8}Ag{sub 4.8}Ge{sub 41.2} when the Ag content increases. At 600 {sup o}C the phase region of the clathrate solution Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} becomes separated from the Ba-Ge boundary and extends from 6.6 to 9.8 at.% Ag. The compound Ba{sub 6}Ge{sub 25} (clathrate type-{Iota}X) dissolves at 800 {sup o}C a maximum of 1.5 at.% Ag. The homogeneity regions of the two ternary compounds BaAg{sub 2-x}Ge{sub 2+x} (ThCr{sub 2}Si{sub 2}-type, 0.2 {<=} x {<=} 0.7) and Ba(Ag{sub 1-x}Ge{sub x}){sub 2} (AlB{sub 2}-type, 0.65 {<=} x {<=} 0.75) were established at 800 deg. C. Studies of transport properties for the series of Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} compounds evidenced that electrons are the predominant charge carriers with the Fermi energy close to a gap. Its position can be fine-tuned by the substitution of Ge by Ag atoms and by mechanical processing of the starting material, Ba{sub 8}Ge{sub 43}. The proximity of the electronic structure at Fermi energy of Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} to a gap is also corroborated by density

Measurement and modeling of high-pressure (vapor + liquid) equilibria of (CO2 + alkanol) binary systems

International Nuclear Information System (INIS)

Bejarano, Arturo; Gutierrez, Jorge E.; Araus, Karina A.; Fuente, Juan C. de la

2011-01-01

Research highlights: → (Vapor + liquid) equilibria of three (CO 2 + C 5 alcohol) binary systems were measured. → Complementary data are reported at (313, 323 and 333) K and from (2 to 11) MPa. → No liquid immiscibility was observed at the temperatures and pressures studied. → Experimental data were correlated with the PR-EoS and the van de Waals mixing rules. → Correlation results showed relative deviations ≤8 % (liquid) and ≤2 % (vapor). - Abstract: Complementary isothermal (vapor + liquid) equilibria data are reported for the (CO 2 + 3-methyl-2-butanol), (CO 2 + 2-pentanol), and (CO 2 + 3-pentanol) binary systems at temperatures of (313, 323, and 333) K, and at pressure range of (2 to 11) MPa. For all (CO 2 + alcohol) systems, it was visually monitored that there was no liquid immiscibility at the temperatures and pressures studied. The experimental data were correlated with the Peng-Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapor + liquid) equilibria compositions were found to be in good agreement with the experimental data with deviations for the mole fractions <8% and <2% for the liquid and vapor phase, respectively.

Computation of thermodynamic equilibria of nuclear materials in multi-physics codes

International Nuclear Information System (INIS)

Piro, M.H.; Lewis, B.J.; Thompson, W.T.; Simunovic, S.; Besmann, T.M.

2011-01-01

A new equilibrium thermodynamic solver is being developed with the primary impetus of direct integration into nuclear fuel performance and safety codes to provide improved predictions of fuel behavior. This solver is intended to provide boundary conditions and material properties for continuum transport calculations. There are several legitimate concerns with the use of existing commercial thermodynamic codes: 1) licensing entanglements associated with code distribution, 2) computational performance, and 3) limited capabilities of handling large multi-component systems of interest to the nuclear industry. The development of this solver is specifically aimed at addressing these concerns. In support of this goal, a new numerical algorithm for computing chemical equilibria is presented which is not based on the traditional steepest descent method or 'Gibbs energy minimization' technique. This new approach exploits fundamental principles of equilibrium thermodynamics, which simplifies the optimization equations. The chemical potentials of all species and phases in the system are constrained by the system chemical potentials, and the objective is to minimize the residuals of the mass balance equations. Several numerical advantages are achieved through this simplification, as described in this paper. (author)

A novel grid multiwing chaotic system with only non-hyperbolic equilibria

Science.gov (United States)

Zhang, Sen; Zeng, Yicheng; Li, Zhijun; Wang, Mengjiao; Xiong, Le

2018-05-01

The structure of the chaotic attractor of a system is mainly determined by the nonlinear functions in system equations. By using a new saw-tooth wave function and a new stair function, a novel complex grid multiwing chaotic system which belongs to non-Shil'nikov chaotic system with non-hyperbolic equilibrium points is proposed in this paper. It is particularly interesting that the complex grid multiwing attractors are generated by increasing the number of non-hyperbolic equilibrium points, which are different from the traditional methods of realising multiwing attractors by adding the index-2 saddle-focus equilibrium points in double-wing chaotic systems. The basic dynamical properties of the new system, such as dissipativity, phase portraits, the stability of the equilibria, the time-domain waveform, power spectrum, bifurcation diagram, Lyapunov exponents, and so on, are investigated by theoretical analysis and numerical simulations. Furthermore, the corresponding electronic circuit is designed and simulated on the Multisim platform. The Multisim simulation results and the hardware experimental results are in good agreement with the numerical simulations of the same system on Matlab platform, which verify the feasibility of this new grid multiwing chaotic system.

Institutions, Equilibria and Efficiency

DEFF Research Database (Denmark)

Competition and efficiency is at the core of economic theory. This volume collects papers of leading scholars, which extend the conventional general equilibrium model in important ways. Efficiency and price regulation are studied when markets are incomplete and existence of equilibria in such set......Competition and efficiency is at the core of economic theory. This volume collects papers of leading scholars, which extend the conventional general equilibrium model in important ways. Efficiency and price regulation are studied when markets are incomplete and existence of equilibria...... in such settings is proven under very general preference assumptions. The model is extended to include geographical location choice, a commodity space incorporating manufacturing imprecision and preferences for club-membership, schools and firms. Inefficiencies arising from household externalities or group...... membership are evaluated. Core equivalence is shown for bargaining economies. The theory of risk aversion is extended and the relation between risk taking and wealth is experimentally investigated. Other topics include: determinacy in OLG with cash-in-advance constraints, income distribution and democracy...

Capabilities for measuring physical and chemical properties of rocks at high pressure

Energy Technology Data Exchange (ETDEWEB)

Durham, W.B. (comp.)

1990-01-01

The Experimental Geophysics Group of the Earth Sciences Department at Lawrence Livermore National Laboratory (LLNL) has experimental equipment that measures a variety of physical properties and phase equilibria and kinetics on rocks and minerals at extreme pressures (to 500 GPa) and temperatures (from 10 to 2800 K). These experimental capabilities are described in this report in terms of published results, photographs, and schematic diagrams.

Ideal MHD beta-limits of poloidally asymmetric equilibria

Energy Technology Data Exchange (ETDEWEB)

Todd, A.M.M.; Miller, A.E.; Grimm, R.C.; Okabayashi, M.; Dalhed, H.E. Jr.

1981-05-01

The ideal MHD stability of poloidally asymmetric equilibria, which are typical of a tokamak reactor design with a single-null poloidal divertor is examined. As with symmetric equilibria, stability to non-axisymmetric modes improves with increasing triangularity and ellipticity, and with lower edge safety factor. Pressure profiles optimized with respect to ballooning stability are obtained for an asymmetric shape, resulting in ..beta../sub critical/ approx. = 5.7%. The corresponding value for an equivalent symmetric shape is ..beta../sub critical/ approx. = 6.5%.

Ideal MHD beta-limits of poloidally asymmetric equilibria

International Nuclear Information System (INIS)

Todd, A.M.M.; Miller, A.E.; Grimm, R.C.; Okabayashi, M.; Dalhed, H.E. Jr.

1981-05-01

The ideal MHD stability of poloidally asymmetric equilibria, which are typical of a tokamak reactor design with a single-null poloidal divertor is examined. As with symmetric equilibria, stability to non-axisymmetric modes improves with increasing triangularity and ellipticity, and with lower edge safety factor. Pressure profiles optimized with respect to ballooning stability are obtained for an asymmetric shape, resulting in β/sub critical/ approx. = 5.7%. The corresponding value for an equivalent symmetric shape is β/sub critical/ approx. = 6.5%

Mathematical Model for Multicomponent Adsorption Equilibria Using Only Pure Component Data

DEFF Research Database (Denmark)

Marcussen, Lis

2000-01-01

A mathematical model for nonideal adsorption equilibria in multicomponent mixtures is developed. It is applied with good results for pure substances and for prediction of strongly nonideal multicomponent equilibria using only pure component data. The model accounts for adsorbent...

Phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC and the formation of TiC in Fe3Al-based alloys

International Nuclear Information System (INIS)

Kobayashi, Satoru; Schneider, Andre; Zaefferer, Stefan; Frommeyer, Georg; Raabe, Dierk

2005-01-01

In the context of the development of high-strength Fe 3 Al-based alloys, phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC phases in the Fe-Al-Cr-Ti-C quinary system and the formation of TiC were determined. A pseudo-eutectic trough (L α + L + TiC) exists at 1470 deg C at around Fe-26Al-5Cr-2Ti-1.7C on the vertical section between Fe-26Al-5Cr (α) and Ti-46C (TiC) in at.%. Large faceted TiC precipitates form from the melt after the formation of primary α phase even in hypoeutectic alloys. The TiC formation is thought to be due to the composition change of the liquid towards the hypereutectic compositions by solidification of the primary α. In order to remove the faceted TiC, which are unfavourable for strengthening the material, two different processing routes have been successfully tested: (i) solidification with an increased rate to reduce the composition variation of the liquid during solidification, and (ii) unidirectional solidification to separate the light TiC precipitates from the melt

Evolution of the Campanian Ignimbrite Magmatic System I: Constraints on Compositional Zonation and Eruption Probability Imposed By Phase Equilibria

Science.gov (United States)

Fowler, S.; Spera, F.; Bohrson, W.; Belkin, H.; Devivo, B.

2005-12-01

discovery of a pseudo-invariant point at ~883°C (Tip) and 0.15 GPa. The fraction of melt changes abruptly from ~0.5 to ~0.1 at Tip due to the simultaneous crystallization of alkali feldspar, plagioclase, spinel, biotite and apatite. At Tip, there is a dramatic decrease in the viscosity of melt (by a factor of four) and magma density (~5%) and an increase in the dissolved H2O content of the melt (from 4.4-5.1 wt%) and in the volume fraction,θ, of supercritical fluid in the multiphase system. In particular, θ increases from ~0.05 at 885°C to ~0.6 at 882°C. The liquid composition also changes discontinuously at Tip with Si, Na, and H2O increasing and K and Al decreasing as temperature falls below Tip. The marked variations in composition and properties of volatile-saturated melt and magma were the trigger that led to the catastrophic eruption and formation of the compositionally-zoned CI magma. Because phase equilibria modeling provides information on the enthalpy changes associated with fractional crystallization and because the dimensions of the CI magma chamber and heat extraction rate can be approximated, a time scale for CI magmatic evolution can be derived. The estimated crystallization duration (τ) is10-100 ka and 75% of τ is spent at or near Tip.

Study of volumetric properties (PVT) of mixtures made of light hydrocarbons (C1-C4), carbon dioxide and hydrogen sulfide - Experimental measurements through a vibrating tube densimeter and modelling; Etude des proprietes volumetriques (PVT) d'hydrocarbures legers (C1-C4), du dioxyde de carbone et de l'hydrogene sulfure. Mesures par densimetrie a tube vibrant et modelisation

Energy Technology Data Exchange (ETDEWEB)

Rivollet, F.

2005-12-15

Various pollutant contents (i.e. carbon dioxide, hydrogen sulphide or other sulphur products) are found in produced oils. These latter must undergo a number of transformations and purifications. The design and dimensioning of the corresponding units can well be optimized only if one has reliable and accurate data about phase equilibria and volumetric properties and of course reliable and accurate modeling. This work was devoted partly to measurements of volumetric properties on three binary mixtures (ethane - hydrogen sulphide, ethane - propane and carbon dioxide - hydrogen sulphide). These measurements were carried out using equipment, comprising a vibrating tube densimeter (Paar, model DMA 512 P), which was especially designed and built for this work. The binary mixtures were studied in the 253 to 363 K temperature range from at pressures up to either 20 or 40 MPa. Two calibration methods of the vibrating tube were used: the FPMC method (Forced Path Mechanical Calibration) described in the literature and an original method containing neural network, developed herein. The study undertaken about the modeling of volumetric properties made it possible to highlight the inadequacy of the traditional use of cubic equations of state to represent simultaneously volumetric properties and phase equilibria. Among the equations of state investigated, a close attention however was paid to cubic equations of state because of their very great use in the oil field. A new tool was found to adapt cubic equations of state to the simultaneous and satisfactory representation of volumetric properties and phase equilibria. It concerns the coupling of the cubic Redlich-Kwong-Soave equation of state with volume correction through a neural network. This new model was tested successfully, it makes it possible to benefit from the existing work of representation of phase equilibria (mixing rules and interaction coefficients) while improving calculation of the volumetric data.

Measurement and modeling of high-pressure (vapour + liquid) equilibria of (CO2 + alcohol) binary systems

International Nuclear Information System (INIS)

Gutierrez, Jorge E.; Bejarano, Arturo; Fuente, Juan C. de la

2010-01-01

An apparatus based on a static-analytic method assembled in this work was utilized to perform high pressure (vapour + liquid) equilibria measurements with uncertainties estimated at 2 + 1-propanol), (CO 2 + 2-methyl-1-propanol), (CO 2 + 3-methyl-1-butanol), and (CO 2 + 1-pentanol) binary systems at temperatures of (313, 323, and 333) K, and at pressure range of (2 to 12) MPa. For all the (CO 2 + alcohol) systems, it was visually monitored to insure that there was no liquid immiscibility at the temperatures and pressures studied. The experimental results were correlated with the Peng-Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapour + liquid) equilibria compositions were found to be in good agreement with the experimental values with deviations for the mol fractions <0.12 and <0.05 for the liquid and vapour phase, respectively.

Recent progress in the relative equilibria of point vortices — In memoriam Hassan Aref

DEFF Research Database (Denmark)

Beelen, Peter; Brøns, Morten; Krishnamurthy, Vikas S.

2013-01-01

Hassan Aref, who sadly passed away in 2011, was one of the world's leading researchers in the dynamics and equilibria of point vortices. We review two problems on the subject of point vortex relative equilibria in which he was engaged at the time of his death: bilinear relative equilibria...

Variational-moment method for computing magnetohydrodynamic equilibria

International Nuclear Information System (INIS)

Lao, L.L.

1983-08-01

A fast yet accurate method to compute magnetohydrodynamic equilibria is provided by the variational-moment method, which is similar to the classical Rayleigh-Ritz-Galerkin approximation. The equilibrium solution sought is decomposed into a spectral representation. The partial differential equations describing the equilibrium are then recast into their equivalent variational form and systematically reduced to an optimum finite set of coupled ordinary differential equations. An appropriate spectral decomposition can make the series representing the solution coverge rapidly and hence substantially reduces the amount of computational time involved. The moment method was developed first to compute fixed-boundary inverse equilibria in axisymmetric toroidal geometry, and was demonstrated to be both efficient and accurate. The method since has been generalized to calculate free-boundary axisymmetric equilibria, to include toroidal plasma rotation and pressure anisotropy, and to treat three-dimensional toroidal geometry. In all these formulations, the flux surfaces are assumed to be smooth and nested so that the solutions can be decomposed in Fourier series in inverse coordinates. These recent developments and the advantages and limitations of the moment method are reviewed. The use of alternate coordinates for decomposition is discussed

Long-term Nash equilibria in electricity markets

International Nuclear Information System (INIS)

Pozo, David; Contreras, Javier; Caballero, Angel; de Andres, Antonio

2011-01-01

In competitive electricity markets, companies simultaneously offer their productions to obtain the maximum profits on a daily basis. In the long run, the strategies utilized by the electric companies lead to various long-term equilibria that can be analyzed with the appropriate tools. We present a methodology to find plausible long-term Nash equilibria in pool-based electricity markets. The methodology is based on an iterative market Nash equilibrium model in which the companies can decide upon their offer strategies. An exponential smoothing of the bids submitted by the companies is applied to facilitate the convergence of the iterative procedure. In each iteration of the model the companies face residual demand curves that are accurately modeled by Hermite interpolating polynomials. We introduce the concept of meta-game equilibrium strategies to allow companies to have a range of offer strategies where several pure and mixed meta-game Nash equilibria are possible. With our model it is also possible to model uncertainty or to generate price scenarios for financial models that assess the value of a generating unit by real options analysis. The application of the proposed methodology is illustrated with several realistic case studies. (author)

Measurement and modeling of high-pressure (vapor + liquid) equilibria of (CO{sub 2} + alkanol) binary systems

Energy Technology Data Exchange (ETDEWEB)

Bejarano, Arturo; Gutierrez, Jorge E. [Departamento de Ingenieria Quimica y Ambiental, Universidad Tecnica Federico Santa Maria, Avda. Espana 1680, Valparaiso (Chile); Araus, Karina A. [Departamento de Ingenieria Quimica y Bioprocesos, Pontificia Universidad Catolica de Chile, Avda. Vicuna Mackenna 4860, Macul, Santiago (Chile); Fuente, Juan C. de la, E-mail: juan.delafuente@usm.c [Departamento de Ingenieria Quimica y Ambiental, Universidad Tecnica Federico Santa Maria, Avda. Espana 1680, Valparaiso (Chile); Centro Regional de Estudios en Alimentos Saludables, Blanco 1623, Valparaiso (Chile)

2011-05-15

Research highlights: (Vapor + liquid) equilibria of three (CO{sub 2} + C{sub 5} alcohol) binary systems were measured. Complementary data are reported at (313, 323 and 333) K and from (2 to 11) MPa. No liquid immiscibility was observed at the temperatures and pressures studied. Experimental data were correlated with the PR-EoS and the van de Waals mixing rules. Correlation results showed relative deviations {<=}8 % (liquid) and {<=}2 % (vapor). - Abstract: Complementary isothermal (vapor + liquid) equilibria data are reported for the (CO{sub 2} + 3-methyl-2-butanol), (CO{sub 2} + 2-pentanol), and (CO{sub 2} + 3-pentanol) binary systems at temperatures of (313, 323, and 333) K, and at pressure range of (2 to 11) MPa. For all (CO{sub 2} + alcohol) systems, it was visually monitored that there was no liquid immiscibility at the temperatures and pressures studied. The experimental data were correlated with the Peng-Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapor + liquid) equilibria compositions were found to be in good agreement with the experimental data with deviations for the mole fractions <8% and <2% for the liquid and vapor phase, respectively.

Institutions, Equilibria and Efficiency

DEFF Research Database (Denmark)

Competition and efficiency is at the core of economic theory. This volume collects papers of leading scholars, which extend the conventional general equilibrium model in important ways. Efficiency and price regulation are studied when markets are incomplete and existence of equilibria in such set...... in OLG, learning in OLG and in games, optimal pricing of derivative securities, the impact of heterogeneity...

Phase equilibria in the KFeS2-Fe-S system at 300-600 °C and bartonite stability

Science.gov (United States)

Osadchii, Valentin O.; Voronin, Mikhail V.; Baranov, Alexander V.

2018-05-01

The article deals with phase relations in the KFeS2-Fe-S system studied by the dry synthesis method in the range of 300-600 °C and at a pressure of 1 bar. At the temperature below 513 ± 3 °C, pyrite coexists with rasvumite and there are pyrite-rasvumite-KFeS2 and pyrite-rasvumite-pyrrhotite equilibria established. Above 513 ± 3 °C pyrite and rasvumite react to form KFeS2 and pyrrhotite, limiting the pyrite-rasvumite association to temperatures below this in nature. The experiments also outline the compositional stability range of the copper-free analog of murunskite (K x Fe2- y S2) and suggest that mineral called bartonite is not stable in the Cl-free system, at least at atmospheric pressure and the temperature in the experiments. Chlorbartonite could be easily produced after adding KCl in the experiment. Possible parageneses in the quaternary K-Fe-S-Cl system were described based on the data obtained in this research and found in the previous studies. The factors affecting the formation of potassium-iron sulfides in nature were discussed.

High pressure study of water-salt systems, phase equilibria, partitioning, thermodynic properties and implication for large icy worlds hydrospheres.

Science.gov (United States)

Journaux, B.; Brown, J. M.; Abramson, E.; Petitgirard, S.; Pakhomova, A.; Boffa Ballaran, T.; Collings, I.

2017-12-01

Water salt systems are predicted to be present in deep hydrosphere inside water-rich planetary bodies, following water/rock chemical interaction during early differentiation stages or later hydrothermal activity. Unfortunately the current knowledge of the thermodynamic and physical properties of aqueous salt mixtures at high pressure and high temperature is still insufficient to allow realistic modeling of the chemical or dynamic of thick planetary hydrospheres. Recent experimental results have shown that the presence of solutes, and more particularly salts, in equilibrium with high pressure ices have large effects on the stability fields, buoyancy and chemistry of all the phases present at these extreme conditions. Effects currently being investigated by our research group also covers ice melting curve depressions that depend on the salt species and incorporation of solutes inside the crystallographic lattice of high pressure ices. Both of these could have very important implication at the planetary scale, enabling thicker/deeper liquid oceans, and allowing chemical transportation through the high pressure ice layer in large icy worlds. We will present the latest results obtained in-situ using diamond anvil cell, coupled with Synchrotron X-Ray diffraction, Raman Spectroscopy and optical observations, allowing to probe the crystallographic structure, equations of state, partitioning and phase boundary of high pressure ice VI and VII in equilibrium with Na-Mg-SO4-Cl ionic species at high pressures (1-10 GPa). The difference in melting behavior depending on the dissolved salt species was characterized, suggesting differences in ionic speciation at liquidus conditions. The solidus P-T conditions were also measured as well as an increase of lattice volumes interpreted as an outcome of ionic incorporation in HP ice during incongruent crystallization. The measured phase diagrams, lattice volumes and important salt incorporations suggest a more complex picture of the

Hermite Polynomials and the Inverse Problem for Collisionless Equilibria

Science.gov (United States)

Allanson, O.; Neukirch, T.; Troscheit, S.; Wilson, F.

2017-12-01

It is long established that Hermite polynomial expansions in either velocity or momentum space can elegantly encode the non-Maxwellian velocity-space structure of a collisionless plasma distribution function (DF). In particular, Hermite polynomials in the canonical momenta naturally arise in the consideration of the 'inverse problem in collisionless equilibria' (IPCE): "for a given macroscopic/fluid equilibrium, what are the self-consistent Vlasov-Maxwell equilibrium DFs?". This question is of particular interest for the equilibrium and stability properties of a given macroscopic configuration, e.g. a current sheet. It can be relatively straightforward to construct a formal solution to IPCE by a Hermite expansion method, but several important questions remain regarding the use of this method. We present recent work that considers the necessary conditions of non-negativity, convergence, and the existence of all moments of an equilibrium DF solution found for IPCE. We also establish meaningful analogies between the equations that link the microscopic and macrosopic descriptions of the Vlasov-Maxwell equilibrium, and those that solve the initial value problem for the heat equation. In the language of the heat equation, IPCE poses the pressure tensor as the 'present' heat distribution over an infinite domain, and the non-Maxwellian features of the DF as the 'past' distribution. We find sufficient conditions for the convergence of the Hermite series representation of the DF, and prove that the non-negativity of the DF can be dependent on the magnetisation of the plasma. For DFs that decay at least as quickly as exp(-v^2/4), we show non-negativity is guaranteed for at least a finite range of magnetisation values, as parameterised by the ratio of the Larmor radius to the gradient length scale. 1. O. Allanson, T. Neukirch, S. Troscheit & F. Wilson: From one-dimensional fields to Vlasov equilibria: theory and application of Hermite polynomials, Journal of Plasma Physics, 82

Oscillations and Multiple Equilibria in Microvascular Blood Flow.

Science.gov (United States)

Karst, Nathaniel J; Storey, Brian D; Geddes, John B

2015-07-01

We investigate the existence of oscillatory dynamics and multiple steady-state flow rates in a network with a simple topology and in vivo microvascular blood flow constitutive laws. Unlike many previous analytic studies, we employ the most biologically relevant models of the physical properties of whole blood. Through a combination of analytic and numeric techniques, we predict in a series of two-parameter bifurcation diagrams a range of dynamical behaviors, including multiple equilibria flow configurations, simple oscillations in volumetric flow rate, and multiple coexistent limit cycles at physically realizable parameters. We show that complexity in network topology is not necessary for complex behaviors to arise and that nonlinear rheology, in particular the plasma skimming effect, is sufficient to support oscillatory dynamics similar to those observed in vivo.

On the uniqueness of fully informative rational expectations equilibria

OpenAIRE

Peter DeMarzo; Costis Skiadas

1998-01-01

This paper analyzes two equivalent equilibrium notions under asymmetric information: risk neutral rational expectations equilibria (rn-REE), and common knowledge equilibria. We show that the set of fully informative rn-REE is a singleton, and we provide necessary and sufficient conditions for the existence of partially informative rn-REE. In a companion paper (DeMarzo and Skiadas (1996)) we show that equilibrium prices for the larger class of quasi-complete economies can be characterized as r...

A note on relative equilibria in a rotating shallow water layer

KAUST Repository

Ait Abderrahmane, Hamid

2013-05-08

Relative equilibria of two and three satellite vortices in a rotating shallow water layer have been recorded via particle image velocimetry (PIV) and their autorotation speed was estimated. This study shows that these equilibria retain the fundamental characteristics of Kelvin\\'s equilibria, and could be adequately described by the classical idealized point vortex theory. The same conclusion can also be inferred using the experimental dataset of Bergmann et al. (J. Fluid Mech., vol. 679, 2011, pp. 415-431; J. Fluid Mech., vol. 691, 2012, pp. 605-606) if the assigned field\\'s contribution to pattern rotation is included. © 2013 Cambridge University Press.

Spinel + quartz-bearing ultrahigh-temperature granulites from Xumayao, Inner Mongolia Suture Zone, North China Craton: Petrology, phase equilibria and counterclockwise p-T path

Directory of Open Access Journals (Sweden)

Huatian Zhang

2012-09-01

Our phase equilibria modeling indicates two main stages during the metamorphic evolution of these rocks: 1 near-isobaric cooling from 975 °C to 875 °C around 8 kbar, represented by the formation of garnet porphyroblasts from spinel and quartz; and 2 cooling and decompression from 850 °C, 8 kbar to below 750 °C, 6.5 kbar, represented by the break-down of garnet. The spinel + quartz assemblage is considered to have been stable at peak metamorphism, formed through the break-down of cordierite, indicating a near isothermal compression process. Our study confirms the regional extent of UHT metamorphism within the IMSZ associated with the Paleoproterozoic subduction-collision process.

Heat capacity and phase equilibria of almandine, Fe3Al2Si3O12

Science.gov (United States)

Anovitz, Lawrence M.; Essene, E.J.; Metz, G.W.; Bohlen, S.R.; Westrum, E.F.; Hemingway, B.S.

1993-01-01

The heat capacity of a synthetic almandine, Fe3Al2Si3O12, was measured from 6 to 350 K using equilibrium, intermittent-heating quasi-adiabatic calorimetry and from 420 to 1000 K using differential scanning calorimetry. These measurements yield Cp298 = 342.80 ?? 1.4 J/mol ?? K and S298o = 342.60 J/mol ?? K. Mo??ssbauer characterizations show the almandine to contain less than 2 ?? 1% of the total iron as Fe3+. X-ray diffraction studies of this synthetic almandine yield a = 11.521 ?? 0.001 A?? and V298o = 115.11 +- 0.01 cm3/mol, somewhat smaller than previously reported. The low-temperature Cp data indicate a lambda transition at 8.7 K related to an antiferromagnetic-paramagnetic transition with TN = 7.5 K. Modeling of the lattice contribution to the total entropy suggests the presence of entropy in excess of that attributable to the effects of lattice vibrations and the magnetic transition. This probably arises from a low-temperature electronic transition (Schottky contribution). Combination of the Cp data with existing thermodynamic and phase equilibrium data on almandine yields ??Gf,298o = -4938.3 kJ/mol and ??Hf,298o= -5261.3 kJ/mol for almandine when calculated from the elements. The equilibrium almandine = hercynite + fayalite + quartz limits the upper T P for almandine and is metastably located at ca. 570??C at P = 1 bar, with a dP dT of +17 bars/??C. This agrees well with reversed experiments on almandine stability when they are corrected for magnetite and hercynite solid-solutions. In {norm of matrix}O2-T space, almandine oxidizes near QFM by the reactions almandine + O2 = magnetite + sillimanite + quartz and almandine + 02 = hercynite + magnetite + quartz. With suitable correction for reduced activities of solid phases, these equilibria provide useful oxygen barometers for medium- to high-grade metamorphic rocks. ?? 1993.

Phase separation and structure formation in gadolinium based liquid and glassy metallic alloys

International Nuclear Information System (INIS)

Han, Junhee

2014-01-01

In this PhD research the liquid-liquid phase separation phenomena in Gd-based alloys was investigated in terms of phase equilibria, microstructure formation upon quenching the melt and corresponding magnetic properties of phase-separated metallic glasses. The phase diagrams of the binary subsystems Gd-Zr and Gd-Ti were experimentally reassessed. Especially the phase equilibria with the liquid phase could be determined directly by combining in situ high energy synchrotron X-ray diffraction with electrostatic levitation of the melt. The Gd-Zr system is of eutectic type with a metastable miscibility gap. The eutectic composition at 18 ± 2 at.% Zr, the liquidus line and the coexistence of bcc-Zr and bcc-Gd at elevated temperature could be determined. The Gd-Ti system is a monotectic system. The experimental observations in this work led to improved new Gd-Zr and Gd-Ti phase diagrams. The phase equilibria of the ternary Gd-Ti-Co system were analyzed for two alloy compositions. The XRD patterns for molten Gd 35 Ti 35 Co 30 gave direct evidence for the coexistence of two liquid phases formed by liquid-liquid phase separation. The first experimental and thermodynamic assessment of the ternary Gd-Ti-Co system revealed that the stable miscibility gap of binary Gd-Ti extends into the ternary Gd-Ti-Co system (up to about 30 at.% Co). New phase-separated metallic glasses were synthesized in Gd-TM-Co-Al (TM = Hf, Ti or Zr) alloys. The microstructure was characterized in terms of composition and cooling rate dependence of phase separation. Due to large positive enthalpy of mixing between Gd on the one side and Hf, Ti or Zr on the other side, the alloys undergo liquid-liquid phase separation during rapid quenching the melt. The parameters determining the microstructure development during phase separation are the thermodynamic properties of the liquid phase, kinetic parameters and quenching conditions. By controlling these parameters and conditions the microstructure can be

Stackelberg equilibria and horizontal differentiation

OpenAIRE

Lambertini, Luca

1993-01-01

This paper proposes a taxonomy of the Stackelberg equilibria emerging from a standard game of horizontal differentiation à la Hotelling in which the strategy set of the sellers in the location stage is the real axis. Repeated leadership appears the most advantageous position. Furthermore, this endogenously yields vertical differentiation between products at equilibrium.

Phase equilibria in Ca–Co–O system

Czech Academy of Sciences Publication Activity Database

Sedmidubský, D.; Jakeš, V.; Jankovský, O.; Leitner, J.; Šofer, Z.; Hejtmánek, Jiří

2012-01-01

Roč. 194, OCT (2012), s. 199-205 ISSN 0022-4596 R&D Projects: GA ČR GA203/09/1036 Institutional research plan: CEZ:AV0Z10100521 Keywords : Ca–Co–O system , Misfit cobaltites, Thermodynamic data, Phase diagrams * misfit cobaltites * thermodynamic data * phase diagrams Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.040, year: 2012

Thermodynamic Equilibria and Extrema Analysis of Attainability Regions and Partial Equilibria

CERN Document Server

Gorban, Alexander N; Kaganovich, Boris M; Keiko, Alexandre V; Shamansky, Vitaly A; Shirkalin, Igor A

2006-01-01

This book discusses mathematical models that are based on the concepts of classical equilibrium thermodynamics. They are intended for the analysis of possible results of diverse natural and production processes. Unlike the traditional models, these allow one to view the achievable set of partial equilibria with regards to constraints on kinetics, energy and mass exchange and to determine states of the studied systems of interest for the researcher. Application of the suggested models in chemical technology, energy and ecology is illustrated in the examples.

MOMCON: A spectral code for obtaining three-dimensional magnetohydrodynamic equilibria

International Nuclear Information System (INIS)

Hirshman, S.P.; Lee, D.K.

1986-01-01

A new code, MOMCON (spectral moments code with constraints), is described that computes three-dimensional ideal magnetohydrodynamic (MHD) equilibria in a fixed toroidal domain using a Fourier expansion for the inverse coordinates (R, Z) representing nested magnetic surfaces. A set of nonlinear coupled ordinary differential equations for the spectral coefficients of (R, Z) is solved using an accelerated steepest descent method. A stream function, lambda, is introduced to improve the mode convergence properties of the Fourier series for R and Z. The convergence rate of the R-Z spectra is optimized on each flux surface by solving nonlinear constraint equations relating the m>=2 spectral coefficients of R and Z. (orig.)

Determination of 3D Equilibria from Flux Surface Knowledge Only

International Nuclear Information System (INIS)

Mynick, H.E.; Pomphrey, N.

2001-01-01

We show that the method of Christiansen and Taylor, from which complete tokamak equilibria can be determined given only knowledge of the shape of the flux surfaces, can be extended to 3-dimensional equilibria, such as those of stellarators. As for the tokamak case, the given geometric knowledge has a high degree of redundancy, so that the full equilibrium can be obtained using only a small portion of that information

Comparison of the thermodynamic properties and high temperature chemical behavior of lanthanide and actinide oxides

International Nuclear Information System (INIS)

Ackermann, R.J.; Rauh, E.G.

1977-01-01

The thermodynamic properties of the lanthanide and actinide oxides are examined, compared, and associated with a variety of high temperature chemical behavior. Trends are cited resulting from a number of thermodynamic and spectroscopic correlations involving solid phases, species in aqueous solution, and molecules and ions in the vapor phase. Inadequacies in the data and alternative approaches are discussed. The characterization of nonstoichiometric phases stable only at high temperatures is related to a network of heterogeneous and homogeneous equilibria. A broad perspective of similarity and dissimilarity between the lanthanides and actinides emerges and forms the basis of the projected needs for further study

Phase-field simulation of solidification in multicomponent alloys coupled with thermodynamic and diffusion mobility databases

International Nuclear Information System (INIS)

Zhang Ruijie; Jing Tao; Jie Wanqi; Liu Baicheng

2006-01-01

To simulate quantitatively the microstructural evolution in the solidification process of multicomponent alloys, we extend the phase-field model for binary alloys to multicomponent alloys with consideration of the solute interactions between different species. These interactions have a great influence not only on the phase equilibria but also on the solute diffusion behaviors. In the model, the interface region is assumed to be a mixture of solid and liquid with the same chemical potential, but with different compositions. The simulation presented is coupled with thermodynamic and diffusion mobility databases, which can accurately predict the phase equilibria and the solute diffusion transportation in the whole system. The phase equilibria in the interface and other thermodynamic quantities are obtained using Thermo-Calc through the TQ interface. As an example, two-dimensional computations for the dendritic growth in Al-Cu-Mg ternary alloy are performed. The quantitative solute distributions and diffusion matrix are obtained in both solid and liquid phases

The feasibility of parameterizing four-state equilibria using relaxation dispersion measurements

International Nuclear Information System (INIS)

Li Pilong; Martins, Ilídio R. S.; Rosen, Michael K.

2011-01-01

Coupled equilibria play important roles in controlling information flow in biochemical systems, including allosteric molecules and multidomain proteins. In the simplest case, two equilibria are coupled to produce four interconverting states. In this study, we assessed the feasibility of determining the degree of coupling between two equilibria in a four-state system via relaxation dispersion measurements. A major bottleneck in this effort is the lack of efficient approaches to data analysis. To this end, we designed a strategy to efficiently evaluate the smoothness of the target function surface (TFS). Using this approach, we found that the TFS is very rough when fitting benchmark CPMG data to all adjustable variables of the four-state equilibria. After constraining a portion of the adjustable variables, which can often be achieved through independent biochemical manipulation of the system, the smoothness of TFS improves dramatically, although it is still insufficient to pinpoint the solution. The four-state equilibria can be finally solved with further incorporation of independent chemical shift information that is readily available. We also used Monte Carlo simulations to evaluate how well each adjustable parameter can be determined in a large kinetic and thermodynamic parameter space and how much improvement can be achieved in defining the parameters through additional measurements. The results show that in favorable conditions the combination of relaxation dispersion and biochemical manipulation allow the four-state equilibrium to be parameterized, and thus coupling strength between two processes to be determined.

Non-existence of Normal Tokamak Equilibria with Negative Central Current

International Nuclear Information System (INIS)

Hammett, G.W.; Jardin, S.C.; Stratton, B.C.

2003-01-01

Recent tokamak experiments employing off-axis, non-inductive current drive have found that a large central current hole can be produced. The current density is measured to be approximately zero in this region, though in principle there was sufficient current-drive power for the central current density to have gone significantly negative. Recent papers have used a large aspect-ratio expansion to show that normal MHD equilibria (with axisymmetric nested flux surfaces, non-singular fields, and monotonic peaked pressure profiles) can not exist with negative central current. We extend that proof here to arbitrary aspect ratio, using a variant of the virial theorem to derive a relatively simple integral constraint on the equilibrium. However, this constraint does not, by itself, exclude equilibria with non-nested flux surfaces, or equilibria with singular fields and/or hollow pressure profiles that may be spontaneously generated

The Effect of CaO on Gas/Slag/Matte/Tridymite Equilibria in Fayalite-Based Copper Smelting Slags at 1473 K (1200 °C) and P(SO2) = 0.25 Atm

Science.gov (United States)

Fallah-Mehrjardi, Ata; Hayes, Peter C.; Jak, Evgueni

2018-04-01

Fundamental experimental studies have been undertaken to determine the effect of CaO on the equilibria between the gas phase (CO/CO2/SO2/Ar) and slag/matte/tridymite phases in the Cu-Fe-O-S-Si-Ca system at 1473 K (1200 °C) and P(SO2) = 0.25 atm. The experimental methodology developed in the Pyrometallurgy Innovation Centre was used. New experimental data have been obtained for the four-phase equilibria system for fixed concentrations of CaO (up to 4 wt pct) in the slag phase as a function of copper concentration in matte, including the concentrations of dissolved sulfur and copper in slag, and Fe/SiO2 ratios in slag at tridymite saturation. The new data provided in the present study are of direct relevance to the pyrometallurgical processing of copper and will be used as an input to optimize the thermodynamic database for the copper-containing multi-component multi-phase system.

Isotropic–Nematic Phase Transitions in Gravitational Systems

Energy Technology Data Exchange (ETDEWEB)

Roupas, Zacharias; Kocsis, Bence [Institute of Physics, Eötvös University, Pázmány P. s. 1/A, Budapest, 1117 (Hungary); Tremaine, Scott [Institute for Advanced Study, Princeton, NJ 08540 (United States)

2017-06-20

We examine dense self-gravitating stellar systems dominated by a central potential, such as nuclear star clusters hosting a central supermassive black hole. Different dynamical properties of these systems evolve on vastly different timescales. In particular, the orbital-plane orientations are typically driven into internal thermodynamic equilibrium by vector resonant relaxation before the orbital eccentricities or semimajor axes relax. We show that the statistical mechanics of such systems exhibit a striking resemblance to liquid crystals, with analogous ordered-nematic and disordered-isotropic phases. The ordered phase consists of bodies orbiting in a disk in both directions, with the disk thickness depending on temperature, while the disordered phase corresponds to a nearly isotropic distribution of the orbit normals. We show that below a critical value of the total angular momentum, the system undergoes a first-order phase transition between the ordered and disordered phases. At a critical point, the phase transition becomes second order, while for higher angular momenta there is a smooth crossover. We also find metastable equilibria containing two identical disks with mutual inclinations between 90° and 180°.

Intermediates and Generic Convergence to Equilibria

DEFF Research Database (Denmark)

Marcondes de Freitas, Michael; Wiuf, Carsten; Feliu, Elisenda

2017-01-01

Known graphical conditions for the generic and global convergence to equilibria of the dynamical system arising from a reaction network are shown to be invariant under the so-called successive removal of intermediates, a systematic procedure to simplify the network, making the graphical conditions...

The Zr-Ti-Cr system. Equilibria at 900 and 1100 C degrees

International Nuclear Information System (INIS)

Arico, Sergio F.; Gribaudo, Luis M.

2003-01-01

Main contributions to the knowledge of the ternary system Zr-Ti-Cr were published in the sixties. Stability domains of phases at temperatures between 500 and 1400 C degrees were there presented. Here, results related to the phase diagram at 900 and 1100 C degrees are informed. Three alloys with 40 at.% Cr and different Zr/Ti ratios and one more, richer in Cr, were elaborated. Specimens of the alloys were heat treated 1000 and 800 h at 900 and 1100 C degrees respectively. Phase characterizations were performed by optic metallography and X-ray diffraction analysis. Compositions were determined by microprobe. Alloys with 40 at.% Cr at both temperatures have biphasic equilibria between the intermetallic Laves phase AB 2 and the body-centered cubic solid solution containing principally zirconium and titanium. The Cr-rich alloy presents equilibrium of the AB 2 compound and the Cr-rich solid solution. Results of the present and previous works are used in order to propose new isothermal sections at 900 and 1100 C degrees. (author)

Experimental Investigation of Gas/Slag/Matte/Tridymite Equilibria in the Cu-Fe-O-S-Si System in Controlled Gas Atmosphere: Experimental Results at 1523 K (1250 °C) and P(SO2) = 0.25 atm

Science.gov (United States)

Fallah-Mehrjardi, Ata; Hidayat, Taufiq; Hayes, Peter C.; Jak, Evgueni

2018-04-01

To assist in the optimization of copper smelting and converting processes, accurate new measurements of the phase equilibria of the Cu-Fe-O-S-Si system have been undertaken. The experimental investigation was focused on the characterization of gas/slag/matte/tridymite equilibria in the Cu-Fe-O-S-Si system at 1523 K (1250 °C), P(SO2) = 0.25 atm, and a range of P(O2)s. The experimental methodology, developed in PYROSEARCH, includes high-temperature equilibration of samples on substrate made from the silica primary phase in controlled gas atmospheres (CO/CO2/SO2/Ar) followed by rapid quenching of the equilibrium condensed phases and direct measurement of the phase compositions with electron-probe X-ray microanalysis (EPMA). The data provided in the present study at 1523 K (1250 °C) and the previous study by the authors at 1473 K (1200 °C) has enabled the determination of the effects of temperature on the phase equilibria of the multicomponent multiphase system, including such characteristics as the chemically dissolved copper in slag and Fe/SiO2 ratio at silica saturation as a function of copper concentration in matte. The new data will be used in the optimization of the thermodynamic database for the copper-containing systems.

Ballooning mode second stability region for sequences of tokamak equilibria

International Nuclear Information System (INIS)

Sugiyama, L.; Mark, J.W.K.

A numerical study of several sequences of tokamak equilibria derived from two flux conserving sequences confirms the tendency of high n ideal MHD ballooning modes to stabilize for values of the plasma beta greater than a second critical beta, for sufficiently favorable equilibria. The major stabilizing effect of increasing the inverse rotational transform profile q(Psi) for equilibria with the same flux surface geometry is shown. The unstable region shifts toward larger shear d ln q/d ln γ and the width of the region measured in terms of the poloidal beta or a pressure gradient parameter, for fixed shear, decreases. The smaller aspect ratio sequences are more sensitive to changes in q and have less stringent limits on the attainable value of the plasma beta in the high beta stable region. Finally, the disconnected mode approximation is shown to provide a reasonable description of the second high beta stability boundary

CRYSTAL CHEMISTRY OF THREE-COMPONENT WHITE DWARFS AND NEUTRON STAR CRUSTS: PHASE STABILITY, PHASE STRATIFICATION, AND PHYSICAL PROPERTIES

Energy Technology Data Exchange (ETDEWEB)

Engstrom, T. A.; Yoder, N. C.; Crespi, V. H., E-mail: tae146@psu.edu, E-mail: ncy5007@psu.edu, E-mail: vhc2@psu.edu [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States)

2016-02-20

A systematic search for multicomponent crystal structures is carried out for five different ternary systems of nuclei in a polarizable background of electrons, representative of accreted neutron star crusts and some white dwarfs. Candidate structures are “bred” by a genetic algorithm and optimized at constant pressure under the assumption of linear response (Thomas–Fermi) charge screening. Subsequent phase equilibria calculations reveal eight distinct crystal structures in the T = 0 bulk phase diagrams, five of which are complicated multinary structures not previously predicted in the context of compact object astrophysics. Frequent instances of geometrically similar but compositionally distinct phases give insight into structural preferences of systems with pairwise Yukawa interactions, including and extending to the regime of low-density colloidal suspensions made in a laboratory. As an application of these main results, we self-consistently couple the phase stability problem to the equations for a self-gravitating, hydrostatically stable white dwarf, with fixed overall composition. To our knowledge, this is the first attempt to incorporate complex multinary phases into the equilibrium phase-layering diagram and mass–radius-composition dependence, both of which are reported for He–C–O and C–O–Ne white dwarfs. Finite thickness interfacial phases (“interphases”) show up at the boundaries between single-component body-centered cubic (bcc) crystalline regions, some of which have lower lattice symmetry than cubic. A second application—quasi-static settling of heavy nuclei in white dwarfs—builds on our equilibrium phase-layering method. Tests of this nonequilibrium method reveal extra phases that play the role of transient host phases for the settling species.

Molecular Structure-Based Methods of Property Prediction in Application to Lipids: A Review and Refinement

DEFF Research Database (Denmark)

Cunico, Larissa; Hukkerikar, Amol; Ceriani, Roberta

2013-01-01

The paper is a review of the combined group contribution (GC)–atom connectivity index (CI) approachfor prediction of physical and thermodynamic properties of organic chemicals and their mixtures withspecial emphasis on lipids. The combined approach employs carefully selected datasets of different...... dependent, have been developed. For mixtures, properties related to phase equilibria aremodeled with GE-based models (UNIQUAC, UNIFAC, NRTL, and combined UNIFAC-CI method). The col-lected phase equilibrium data for VLE and SLE have been tested for thermodynamic consistency togetherwith a performance...... evaluation of the GE-models. The paper also reviews the role of the databases andthe mathematical and thermodynamic consistency of the measured/estimated data and the predictivenature of the developed models....

Toroidal Extrap Equilibria

International Nuclear Information System (INIS)

Scheffel, J.

1982-04-01

Ideal MHD-equilibria for the toroidal EXTRAP configuration have been computed with an equilibrium code. The free-boundary prob- lem is solved by using the condition that the current density is proportional to r on a flux surface. It is found that the toroidal Z-pinch, initially induced in the central zero-field region of a transverse octupole field, drifts radially outwards producing an inverse -D shaped cross-section. The plasma current of this high- beta equilibrium may be increased if the plasma is pushed back by altering the external confining magnetic field as demonstrated. (Author)

Equilibres de phases dans les systèmes fluides petroliers-eau Phase Equilibria in Oil-Water Systems

Directory of Open Access Journals (Sweden)

Peneloux A.

2006-11-01

Full Text Available Nous présentons quelques résultats obtenus à partir du logiciel FHYD qui permet le traitement des mélanges eau-fluides pétroliers, avec la détermination de la nature des phases (huile-gaz-eau-hydrate thermodynamiquement stables dans des conditions données de température et de pression, ainsi que de la quantité, de la composition de ces différentes phases et de leurs propriétés. Ce logiciel permet le tracé automatique des diagrammes de phases et nous présentons des exemples, depuis les systèmes binaires (eau-éthane, ternaires (eau-méthane-propane jusqu'aux fluides les plus complexes. La présence de sels (chlorure de sodium dissous est envisagée, ainsi que le calcul des conditions de dépôt du sel solide. Des exemples de problèmes pétroliers sont cités (gaz de séparateur saturé en eau, huile saturée en eau dans les conditions de gisement, huile en présence d'eau salée. Les estimations sur les quantités d'hydrate formées et leurs compositions sont comparées à des données expérimentales et aux résultats obtenus par d'autres logiciels. Le programme FHYD pourrait permettre une représentation plus réaliste de l'évolution des fluides pétroliers et des propriétés de transport de leurs différentes phases dans les modèles de simulation des conduites polyphasiques. This article presents a selection of results obtained with the FHYD program. This software allows simulation of mixtures composed of petroleum fluids and water, with determination of the nature of thermodynamically stable phases (oil-gas-water-hydrate under given conditions of temperature and pressure, along with the quantity, composition and properties of these different phases. Additionally, the program can automatically produce phase diagrams. Several examples of these have been included here, ranging from binary systems (water-ethane and ternary systems (water-methane-propane to the most complex petroleum fluids. The presence of dissolved salts

How hard is it to find extreme Nash equilibria in network congestion games?

NARCIS (Netherlands)

Gassner, E.; Hatzl, J.; Krumke, S.O.; Sperber, H.; Woeginger, G.J.; Papadimitriou, C.; Zhang, S.

2008-01-01

We study the complexity of finding extreme pure Nash equilibria in symmetric (unweighted) network congestion games. In our context best and worst equilibria are those with minimum respectively maximum makespan. On series-parallel graphs a worst Nash equilibrium can be found by a Greedy approach

Prediction of vapour-liquid and vapour-liquid-liquid equilibria of nitrogen-hydrocarbon mixtures used in J-T refrigerators

Science.gov (United States)

Narayanan, Vineed; Venkatarathnam, G.

2018-03-01

Nitrogen-hydrocarbon mixtures are widely used as refrigerants in J-T refrigerators operating with mixtures, as well as in natural gas liquefiers. The Peng-Robinson equation of state has traditionally been used to simulate the above cryogenic process. Multi parameter Helmholtz energy equations are now preferred for determining the properties of natural gas. They have, however, been used only to predict vapour-liquid equilibria, and not vapour-liquid-liquid equilibria that can occur in mixtures used in cryogenic mixed refrigerant processes. In this paper the vapour-liquid equilibrium of binary mixtures of nitrogen-methane, nitrogen-ethane, nitrogen-propane, nitrogen-isobutane and three component mixtures of nitrogen-methane-ethane and nitrogen-methane-propane have been studied with the Peng-Robinson and the Helmholtz energy equations of state of NIST REFPROP and compared with experimental data available in the literature.

Vapor Pressure Plus: An Experiment for Studying Phase Equilibria in Water, with Observation of Supercooling, Spontaneous Freezing, and the Triple Point

Science.gov (United States)

Tellinghuisen, Joel

2010-01-01

Liquid-vapor, solid-vapor, and solid-liquid-vapor equilibria are studied for the pure substance water, using modern equipment that includes specially fabricated glass cells. Samples are evaporatively frozen initially, during which they typically supercool to -5 to -10 [degrees]C before spontaneously freezing. Vacuum pumping lowers the temperature…

Resurrecting Equilibria Through Cycles

DEFF Research Database (Denmark)

Barnett, Richard C.; Bhattacharya, Joydeep; Bunzel, Helle

equilibria because they asymptotically violate some economic restriction of the model. The literature has always ruled out such paths. This paper studies a pure-exchange monetary overlapping generations economy in which real balances cycle forever between momentary equilibrium points. The novelty is to show...... that segments of the offer curve that have been previously ignored, can in fact be used to produce asymptotically valid cyclical paths. Indeed, a cycle can bestow dynamic validity on momentary equilibrium points that had erstwhile been classified as dynamically invalid....

The design of magnetic diagnostics for reconstructing of NCSX stellarator equilibria

International Nuclear Information System (INIS)

Lazarus, E.A.; Pomphrey, N.

2005-01-01

In previous work we have demonstrated that NCSX (National Compact Stellarator Experiment) will require active control of the helical and poloidal field coils in order to remain on a stable trajectory to high beta while retaining quasi-axisymmetry. We require a set of magnetic diagnostics that will be sensitive to changes in the equilibrium that represent departures from such a trajectory. That is, we will need to control features of the plasma boundary shape to a specification; that specification itself will vary with the current and pressure profiles. We need to determine a satisfactory set of magnetic sensors for this task To address this we have postulated a diagnostic set of 443 sensors that we believe is overly complete. A data base of ∼2500 free-boundary equilibria is created with variation of coil currents, plasma pressure and toroidal current profiles, plasma size, total pressure and total current. The signals expected on this array of diagnostics are calculated using a response function formalism. These are used in a linear regression to predict the magnetic field on a smallest vacuum surface that encompasses all the equilibria in the database. We have extended a standard 'variable selection' method of multivariate statistics to determine a complete ranking of the sensors. The ranking scheme is based on properties of the null space of the matrix of diagnostic signals for all equilibria in the database. Subsets are chosen according to this ranking and we judge adequacy by our ability to reconstruct the equilibrium with STELLOPT. While the ability to reconstruct the equilibrium in free boundary does not yield information on optimal control algorithms, it does show whether a particular set of sensors contains the necessary information to allow control of the plasma. Results will be reported. It is yet to be determined just how much information about the profiles can be known from external measurements. We will present results of a study that addresses this

Modelling of phase equilibria in CH4–C2H6–C3H8–nC4H10–NaCl–H2O systems

International Nuclear Information System (INIS)

Li, Jun; Zhang, Zhigang; Luo, Xiaorong; Li, Xiaochun

2015-01-01

Highlights: • A new model was established for the phase equilibria of C1–C2–C3–nC4–brine systems. • The model can reproduce of hydrocarbon–brine equilibria to high T&P and salinity. • The model can well predict H 2 O solubility in light hydrocarbon rich phases. - Abstract: A thermodynamic model is presented for the mutual solubility of CH 4 –C 2 H 6 –C 3 H 8 –nC 4 H 10 –brine systems up to high temperature, pressure and salinity. The Peng–Robinson model is used for non-aqueous phase fugacity calculations, and the Pitzer model is used for aqueous phase activity calculations. The model can accurately reproduce the experimental solubilities of CH 4 , C 2 H 6 , C 3 H 8 and nC 4 H 10 in water or NaCl solutions and H 2 O solubility in the non-aqueous phase. The experimental data of mutual solubility for the CH 4 –brine subsystem are sufficient for temperatures exceeding 250 °C, pressures exceeding 1000 bar and NaCl molalities greater than 6 molal. Compared to the CH 4 –brine system, the mutual solubility data of C 2 H 6 –brine, C 3 H 8 –brine and nC 4 H 10 –brine are not sufficient. Based on the comparison with the experimental data of H 2 O solubility in C 2 H 6 -, C 3 H 8 - or nC 4 H 10 -rich phases, the model has an excellent capability for the prediction of H 2 O solubility in hydrocarbon-rich phases, as these experimental data were not used in the modelling. Predictions of hydrocarbon solubility (at temperatures up to 200 °C, pressures up to 1000 bar and NaCl molalities greater than 6 molal) were made for the C 2 H 6 –brine, C 3 H 8 –brine and nC 4 H 10 –brine systems. The predictions suggest that increasing pressure generally increases the hydrocarbon solubility in water or brine, especially in the lower-pressure region. Increasing temperature usually decreases the hydrocarbon solubility at lower temperatures but increases the hydrocarbon solubility at higher temperatures. Increasing water salinity dramatically decreases

Sloshing-ion equilibria in the TARA endplugs

International Nuclear Information System (INIS)

Hokin, S.; Kesner, J.

1983-11-01

We have employed a modified version of the LLNL Bounce-average Fokker-Planck code to model neutral beam-produced sloshing-ion equilibria in the TARA endplugs. The questions we have addressed concern the effect of deuterium beam operation as opposed to hydrogen operation, and the advantage of using full-energy beams rather than the usual three-component beams. We find that, for the expected base case TARA operating parameters, a 40% savings in required beam power is attained by using deuterium beams rather than hydrogen beams, and that the use of full-energy beams results in an additional 26% power savings for these parameters. For higher plasma temperatures the use of full-energy beams becomes significantly advantagous. We have also investigated the equilibria of two possible alternate mirror configurations for the TARA endplugs, believed to be more stable to trapped particle modes, and report those results here

Reduction of Islands in Full-pressure Stellarator Equilibria

International Nuclear Information System (INIS)

Hudson, S.R.; Monticello, D.A.; Reiman, A.H.

2001-01-01

The control of magnetic islands is a crucial issue in designing Stellarators. Islands are associated with resonant radial magnetic fields at rational rotational-transform surfaces and can lead to chaos and poor plasma confinement. In this article, we show that variations in the resonant fields of a full-pressure stellarator equilibrium can be related to variations in the boundary via a coupling matrix, and inversion of this matrix determines a boundary modification for which the island content is significantly reduced. The numerical procedure is described and the results of island optimization are presented. Equilibria with islands are computed using the Princeton Iterative Equilibrium Solver, and resonant radial fields are calculated via construction of quadratic-flux-minimizing surfaces. A design candidate for the National Compact Stellarator Experiment [Phys. Plasmas 8, 2001], which has a large island, is used to illustrate the technique. Small variations in the boundary shape are used to reduce island size and to reverse the phase of a major island chain

Re-analysis of exponential rigid-rotor astron equilibria

International Nuclear Information System (INIS)

Lovelace, R.V.; Larrabee, D.A.; Fleischmann, H.H.

1978-01-01

Previous studies of exponential rigid-rotor astron equilibria include particles which are not trapped in the self-field of the configuration. The modification of these studies required to exclude untrapped particles is derived

Correlation and prediction of ion exchange equilibria on weak-acid resins by means of the surface complex formation model

International Nuclear Information System (INIS)

Horst, J.

1988-11-01

The present work summarizes investigations of the equilibrium of the exchange of protons, copper, zinc, calcium, magnesium and sodium ions on two weak-acid exchange resins in hydrochloric and carbonic acid bearing solutions at 25 0 C. The description of the state of equilibrium between resin and solution is based on the individual chemical equilibria which have to be adjusted simultaneously. The equilibrium in the liquid phase is described by the mass action law and the condition of electroneutrality using activity coefficients calculated according to the theory of Debye and Hueckel. The exchange equilibria are described by means of a surface complex formation model, which was developed by Davis, James and Leckie for activated aluminia and which has been applied to weak-acid resins. The model concept assumes the resin as a plane surface in which the functional groups are distributed uniformly. (orig./RB) [de

Study of phase equilibria in function of temperature in UO2-PuO2-Pu2O3 system for nuclear ceramics with high plutonium contents

International Nuclear Information System (INIS)

Truphemus, Thibaut

2013-01-01

In the UO 2 -PuO 2 -Pu 2 O 3 section, a monophasic (U 1-y ,Pu y )O 2-x domain is stable for y≤0,20 at 25 C and up to solid-liquid equilibrium. At higher Pu content, phase equilibria are more unclear with a phase separation process. The main objective of this work consisted in upgrading the representation of this system for 0,15≤y≤0,65 and 25≤T(C)≤1500. At 25 C, a miscibility gap composed by two different (U 1-y ,Pu y )O 2-x phases has been observed for y≤0,45, with one very closed to stoichiometric state (Oxygen/Metal=2) and one other very reduced. For the first time, a triphasic domain has been characterized at higher Pu contents, with two (U 1-y ,Pu y )O 2-x phases near y=0,45 and one (U 1-y ,Pu y ) 2 O 3 phase with a low U content inside. Concerning the study in function of temperature, we have demonstrated that phase separation temperature increase when Pu content grows. Several representations have been established. At 200 C, the representation is closed to that at 25 C. At 400 C, the phase separation have been specified at a lower Pu content than that of literature: y=0,35. At 600 C, our results have clarified the section, until then very unclear, with a phase separation appearing at y=0,60.The microstructural analysis has clearly demonstrated the significant impact of the phase separation on the material. Indeed many cracks have been observed in our samples, and quantity of these defects increases when Pu content grows. (author) [fr

Thermal effects of variable material properties and metamorphic reactions in a three-component subducting slab

DEFF Research Database (Denmark)

Chemia, Zurab; Dolejš, David; Steinle-Neumann, Gerd

2015-01-01

We explore the effects of variable material properties, phase transformations, and metamorphic devolatilization reactions on the thermal structure of a subducting slab using thermodynamic phase equilibrium calculations combined with a thermal evolution model. The subducting slab is divided...... into three layers consisting of oceanic sediments, altered oceanic crust, and partially serpentinized or anhydrous harzburgite. Solid-fluid equilibria and material properties are computed for each layer individually to illustrate distinct thermal consequences when chemical and mechanical homogenization...... indicate that subducting sediments and oceanic crust warm by 40 and 70°C, respectively, before the effect of wedge convection and heating is encountered at 1.7 GPa. Retention of fluid in the slab pore space plays a negligible role in oceanic crust and serpentinized peridotites. By contrast, the large...

Equilibrator: Modeling Chemical Equilibria with Excel

Science.gov (United States)

Vander Griend, Douglas A.

2011-01-01

Equilibrator is a Microsoft Excel program for learning about chemical equilibria through modeling, similar in function to EQS4WIN, which is no longer supported and does not work well with newer Windows operating systems. Similar to EQS4WIN, Equilibrator allows the user to define a system with temperature, initial moles, and then either total…

Quaternary (liquid + liquid) equilibria of aqueous two-phase polyethylene glycol, poly-N-vinylcaprolactam, and KH{sub 2}PO{sub 4}: Experimental and the generalized Flory-Huggins theory

Energy Technology Data Exchange (ETDEWEB)

Foroutan, Masumeh [Department of Physical Chemistry, Faculty of Chemistry, College of Science, University of Tehran, Enghelab Ave., Tehran 14155-6455 (Iran, Islamic Republic of)], E-mail: foroutan@khayam.ut.ac.ir; Zarrabi, Mona [Department of Physical Chemistry, Faculty of Chemistry, College of Science, University of Tehran, Enghelab Ave., Tehran 14155-6455 (Iran, Islamic Republic of)

2008-06-15

A quaternary (liquid + liquid) equilibrium study was performed to focus attention on the interaction parameters between poly-N-vinylcaprolactam (PVCL) and poly-ethylene glycol (PEG) as well as between other species. At first, the new experimental data of (liquid + liquid) equilibria for aqueous two-phase systems containing PEG, KH{sub 2}PO{sub 4}, and PVCL at T = 303.15 K have been determined. Then the Flory-Huggins theory with two electrostatic terms (the Debye-Huckel and the Pitzer-Debye-Huckel equations) has been generalized to correlate the phase behavior of the quaternary system. Good agreement has been found between experimental and calculated data from both models especially from the Pitzer-Debye-Huckel equation. Also an effort was done to compare the effect of temperature as well as addition of PVCL on the binodal curves of PEG, KH{sub 2}PO{sub 4}, and water. The effect of the type of salt on the binodals has been also studied, and the salting out power of the salts has been determined.

Nash equilibria via duality and homological selection

Indian Academy of Sciences (India)

1Quantitative Methods and Information Systems Area, Indian Institute ... The original proof of existence of Nash equilibria [13] uses fairly ...... The fiber over a regular point a of the disk Di consists of three inverse images (labeled. A1,A2,A3 in ...

Recent developments in Bayesian inference of tokamak plasma equilibria and high-dimensional stochastic quadratures

International Nuclear Information System (INIS)

Von Nessi, G T; Hole, M J

2014-01-01

We present recent results and technical breakthroughs for the Bayesian inference of tokamak equilibria using force-balance as a prior constraint. Issues surrounding model parameter representation and posterior analysis are discussed and addressed. These points motivate the recent advancements embodied in the Bayesian Equilibrium Analysis and Simulation Tool (BEAST) software being presently utilized to study equilibria on the Mega-Ampere Spherical Tokamak (MAST) experiment in the UK (von Nessi et al 2012 J. Phys. A 46 185501). State-of-the-art results of using BEAST to study MAST equilibria are reviewed, with recent code advancements being systematically presented though out the manuscript. (paper)

Theory of pressure-induced islands and self-healing in three-dimensional toroidal magnetohydrodynamic equilibria

International Nuclear Information System (INIS)

Bhattacharjee, A.; Hayashi, T.; Hegna, C.C.; Nakajima, N.; Sato, T.

1994-11-01

The role of singular currents in three-dimensional toroidal equilibria and their resolution by magnetic island formation is discussed from both analytical and computational points of view. Earlier analytical results are extended to include small vacuum islands which may, in general, have different phases with respect to pressure-induced islands. In currentless stellarators, the formation of islands is shown to depend on the resistive parameter D R as well as the integrated effect of global Pfirsch-Schlueter currents. It is demonstrated that the pressure-induced 'self-healing' effect, recently discovered computationally, is also predicted by analytical theory. (author)

Séparations par changement de phase. Etude et représentation des équilibres liquide-vapeur Separation by Phase Hange. Study and Computing Liquid-Vapor Equilibria

Directory of Open Access Journals (Sweden)

Asselineau L.

2006-11-01

Full Text Available Pour concevoir et optimiser les principales opérations de séparation (particulièrement les distillations avec ou sans solvant et l'extraction liquide-liquide on doit disposer de méthodes de corrélation ou, mieux, de prédiction des équilibres entre phases. A basse pression, et pour les mélanges d'hydrocarbures, les résultats présentés permettent la prévision des coefficients d'équilibre, même pour les séparations les plus délicates. En présence de constituants polaires, les données expérimentales d'équilibre liquide-liquide et liquide-vapeur de mélanges binaires et ternaires peuvent être simultanément corrélées dans le but de simuler et d'optimiser les distillations azéotropiques ou extractives. Sous haute pression, et particulièrement aux abords immédiats du point critique, le choix d'une équation d'état conduit à un traitement unitaire des phases en présence et permet, en particulier, la prédiction du lieu des points critiques des mélanges d'hydrocarbures et la corrélation de ce lieu en présence de solvants polaires. To determine and optimize the main separation operations (in particular distillations with or without a solvent, and liquid-liquid extraction correlation methods must be available or, better yet, methods of predicting phase equilibria. At low pressure and for hydrocarbon mixtures, the results described make the prediction of equilibrium coefficients possible, even for the most delicate separation. In the presence of polar constituents, the experimental data for the liquid-liquid and liquid-vapor equilibrium of binary and ternary mixtures can be simultaneously correlaten so as to simulate and optimize azeotropic or extractive distillations. Under high pressure and especially in the immediate vicinityof the critical point, the choice of an equation of state leads ta a unit treatment of the phases present and, in particular, makes it possible to predict the location of critical points in hydrocarbon

On the stability of dissipative MHD equilibria

International Nuclear Information System (INIS)

Teichmann, J.

1979-04-01

The global stability of stationary equilibria of dissipative MHD is studied uisng the direct Liapunov method. Sufficient and necessary conditions for stability of the linearized Euler-Lagrangian system with the full dissipative operators are given. The case of the two-fluid isentropic flow is discussed. (orig.)

A Continuous Family of Equilibria in Ferromagnetic Media are Ground States

Science.gov (United States)

Su, Xifeng; de la Llave, Rafael

2017-09-01

We show that a foliation of equilibria (a continuous family of equilibria whose graph covers all the configuration space) in ferromagnetic transitive models are ground states. The result we prove is very general, and it applies to models with long range and many-body interactions. As an application, we consider several models of networks of interacting particles including models of Frenkel-Kontorova type on Z^d and one-dimensional quasi-periodic media. The result above is an analogue of several results in the calculus of variations (fields of extremals) and in PDE's. Since the models we consider are discrete and long range, new proofs need to be given. We also note that the main hypothesis of our result (the existence of foliations of equilibria) is the conclusion (using KAM theory) of several recent papers. Hence, we obtain that the KAM solutions recently established are minimizers when the interaction is ferromagnetic and transitive (these concepts are defined later).

Inverse plasma equilibria

International Nuclear Information System (INIS)

Hicks, H.R.; Dory, R.A.; Holmes, J.A.

1983-01-01

We illustrate in some detail a 2D inverse-equilibrium solver that was constructed to analyze tokamak configurations and stellarators (the latter in the context of the average method). To ensure that the method is suitable not only to determine equilibria, but also to provide appropriately represented data for existing stability codes, it is important to be able to control the Jacobian, tilde J is identical to delta(R,Z)/delta(rho, theta). The form chosen is tilde J = J 0 (rho)R/sup l/rho where rho is a flux surface label, and l is an integer. The initial implementation is for a fixed conducting-wall boundary, but the technique can be extended to a free-boundary model

Looking for multiple equilibria when geography matters : German city growth and the WWII shock

NARCIS (Netherlands)

Bosker, Maarten; Brakman, Steven; Garretsen, Harry; Schramm, Marc

Based on the methodology of Davis and Weinstein, we look for multiple equilibria in German city growth. Bytaking the bombing of Germany during WWII as an example of a large, temporary shock, we analyze whether German city growth is characterized by multiple equilibria. In doing so, we allow for

On the application of the NRTL method to ternary (liquid + liquid) equilibria

International Nuclear Information System (INIS)

Alvarez Julia, Jorge; Barrero, Carmen R.; Corso, Maria E.; Grande, Maria del Carmen; Marschoff, Carlos M.

2005-01-01

The use of the NRTL method for correlating experimental data in ternary (liquid + liquid) equilibria is considered. It is concluded that parameters obtained by direct correlation techniques have not a direct physical meaning. Also, it is shown that the resulting values for these parameters depend on the number of experimental points considered and on the particular calculation method employed. Thus, it is very risky to employ such parameters in predicting equilibria of other ternary mixtures

A stable algorithm for calculating phase equilibria with capillarity at specified moles, volume and temperature using a dynamic model

KAUST Repository

Kou, Jisheng; Sun, Shuyu

2017-01-01

Capillary pressure can significantly affect the phase properties and flow of liquid-gas fluids in porous media, and thus, the phase equilibrium calculation incorporating capillary pressure is crucial to simulate such problems accurately. Recently

Status of thermophysical properties data for pure fluids and mixtures of cryogenic interest

International Nuclear Information System (INIS)

Haynes, W.M.; Hiza, M.J.; Kidney, A.J.; Olien, N.A.

1984-01-01

This chapter discusses the importance, availability, and deficiencies of the existing data bases for the thermophysical properties of cryogenic fluids, including mixtures, considering both scientific and engineering interests. The following types of phase equilibria are emphasized: liquid-vapor, solid-vapor, liquid-liquid (or liquid-liquid-vapor), and solid-liquid (or solid-liquid-vapor). The available thermophysical properties data for both pure fluids and mixtures are summarized. Specific recommendations are made for future experimental measurements. It is predicted that the major thrust of future studies of cryogenic fluids will involve mixtures. The fluids considered include those involved in cryogenic processing with melting temperatures below ambient

Multi-region approach to free-boundary three-dimensional tokamak equilibria and resistive wall instabilities

Science.gov (United States)

Ferraro, N. M.; Jardin, S. C.; Lao, L. L.; Shephard, M. S.; Zhang, F.

2016-05-01

Free-boundary 3D tokamak equilibria and resistive wall instabilities are calculated using a new resistive wall model in the two-fluid M3D-C1 code. In this model, the resistive wall and surrounding vacuum region are included within the computational domain. This implementation contrasts with the method typically used in fluid codes in which the resistive wall is treated as a boundary condition on the computational domain boundary and has the advantage of maintaining purely local coupling of mesh elements. This new capability is used to simulate perturbed, free-boundary non-axisymmetric equilibria; the linear evolution of resistive wall modes; and the linear and nonlinear evolution of axisymmetric vertical displacement events (VDEs). Calculated growth rates for a resistive wall mode with arbitrary wall thickness are shown to agree well with the analytic theory. Equilibrium and VDE calculations are performed in diverted tokamak geometry, at physically realistic values of dissipation, and with resistive walls of finite width. Simulations of a VDE disruption extend into the current-quench phase, in which the plasma becomes limited by the first wall, and strong currents are observed to flow in the wall, in the SOL, and from the plasma to the wall.

Multi-region approach to free-boundary three-dimensional tokamak equilibria and resistive wall instabilities

Energy Technology Data Exchange (ETDEWEB)

Ferraro, N. M., E-mail: nferraro@pppl.gov; Lao, L. L. [General Atomics, La Jolla, California 92186 (United States); Jardin, S. C. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Shephard, M. S.; Zhang, F. [Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2016-05-15

Free-boundary 3D tokamak equilibria and resistive wall instabilities are calculated using a new resistive wall model in the two-fluid M3D-C1 code. In this model, the resistive wall and surrounding vacuum region are included within the computational domain. This implementation contrasts with the method typically used in fluid codes in which the resistive wall is treated as a boundary condition on the computational domain boundary and has the advantage of maintaining purely local coupling of mesh elements. This new capability is used to simulate perturbed, free-boundary non-axisymmetric equilibria; the linear evolution of resistive wall modes; and the linear and nonlinear evolution of axisymmetric vertical displacement events (VDEs). Calculated growth rates for a resistive wall mode with arbitrary wall thickness are shown to agree well with the analytic theory. Equilibrium and VDE calculations are performed in diverted tokamak geometry, at physically realistic values of dissipation, and with resistive walls of finite width. Simulations of a VDE disruption extend into the current-quench phase, in which the plasma becomes limited by the first wall, and strong currents are observed to flow in the wall, in the SOL, and from the plasma to the wall.

Investigations of (acid+base) equilibria in systems modelling interactions occurring in biomolecules

International Nuclear Information System (INIS)

Kozak, Anna; Czaja, Malgorzata; Chmurzynski, Lech

2006-01-01

By using the potentiometric microtitration method, acidity constants, K a , anionic, K AHA - , and cationic, K BHB + , homoconjugation constants, as well as molecular heteroconjugation, K BHA , constants have been determined in (acid+base) systems formed by the following compounds: acetic acid, phenol, n-butylamine, imidazole, and 4(5)-methylimidazole. These compounds constitute fragments of the side chains of amino acids capable of proton exchange in active sites of enzymes. The (acid+base) equilibria were studied in five polar solvents of different properties, namely in aprotic protophobic acetonitrile, acetone and propylene carbonate, in aprotic protophilic dimethyl sulfoxide and in amphiprotic methanol. The lowest values of the acidity constants of the molecular and cationic acids have been found in aprotic protophobic polar solvents - acetonitrile, propylene carbonate and acetone. Their acid strength have been found to depend on solvent basicity expressed as donor numbers, DN. These media, in particular acetonitrile and acetone, are also favourable for establishing molecular homo- and heteroconjugation equilibria. The most stable homocomplexes are formed in the case of acetic acid (K AHA - values range from 2.26 to 3.56 in these media, being more than an order of magnitude higher than those for the remaining compounds). The magnitudes of lgK BHA reveal that the most stable heterocomplexes are formed by n-butylamine and acetic acid that are characterized by the smallest differences in pK a values

Computing Proper Equilibria of Zero-Sum Games

DEFF Research Database (Denmark)

Miltersen, Peter Bro; Sørensen, Troels Bjerre

2007-01-01

We show that a proper equilibrium of a matrix game can be found in polynomial time by solving a linear (in the number of pure strategies of the two players) number of linear programs of roughly the same dimensions as the standard linear programs describing the Nash equilibria of the game....

On the stochastic stability of MHD equilibria

International Nuclear Information System (INIS)

Teichmann, J.

1979-07-01

The stochastic stability in the large of stationary equilibria of ideal and dissipative magnetohydrodynamics under the influence of stationary random fluctuations is studied using the direct Liapunov method. Sufficient and necessary conditions for stability of the linearized Euler-Lagrangian systems are given. The destabilizing effect of stochastic fluctuations is demonstrated. (orig.)

Thermodynamic properties of minerals: Macroscopic and microscopic approaches

International Nuclear Information System (INIS)

Richet, P.; Gillet, P.; Fiquet, G.

1992-01-01

Thermodynamic modeling of experimental or natural-phase equilibria has become an integral part of petrology. In this respect, the isobaric heat capacity (C p ) has manifold importance. First, C p data constitute the basis of third-law determinations of the entropy of minerals. Second, these data are needed to calculate the variation with temperature of the entropy, the entropy, and the Gibbs free energy. As a result, it necessary to know accurately heat capacities when retrieving thermodynamic information from phase equilibria data, especially when trying to separate the effects of the enthalpies and entropies of transformation. In this paper, we broadly review the main empiricial and theoretical aspects of the heat capacity of minerals. We begin with a brief review of the three main techniques that are currently in use for determining heat capacities from 0 to 2000 K, namely, adiabatic, differential scanning (DSC), and drop colarimetry, paying attention to the experimental constraints that limit measurements to certain conditions. When minerals can be subjected at best to limited calorimetric measurements, either because of lack of gram-sized samples or of instability at high temperatures (as if often the case with high-pressure minerals), other ways have to be found for predicting standard entropies and high-temperature properties. The validity of empiricial methods of prediction of the heat capacity as a function of temperature and composition will thus be discussed

Computational study of the influence of mirror parameters on FRC (field-reversed configuration) equilibria:

International Nuclear Information System (INIS)

Fuentes, N.O.; Sakanaka, P.H.

1990-01-01

Field-reversed configuration equilibria are studied by solving the Grad-Shafranov equation. A multiple coil system (main coil and end mirrors) is considered to simulate the coil geometry of CNEA device. First results are presented for computed two-dimensional FRC equilibria produced varying the mirror coil current with two different mirror lenghts. (Author)

Signaling equilibria in sensorimotor interactions.

Science.gov (United States)

Leibfried, Felix; Grau-Moya, Jordi; Braun, Daniel A

2015-08-01

Although complex forms of communication like human language are often assumed to have evolved out of more simple forms of sensorimotor signaling, less attention has been devoted to investigate the latter. Here, we study communicative sensorimotor behavior of humans in a two-person joint motor task where each player controls one dimension of a planar motion. We designed this joint task as a game where one player (the sender) possesses private information about a hidden target the other player (the receiver) wants to know about, and where the sender's actions are costly signals that influence the receiver's control strategy. We developed a game-theoretic model within the framework of signaling games to investigate whether subjects' behavior could be adequately described by the corresponding equilibrium solutions. The model predicts both separating and pooling equilibria, in which signaling does and does not occur respectively. We observed both kinds of equilibria in subjects and found that, in line with model predictions, the propensity of signaling decreased with increasing signaling costs and decreasing uncertainty on the part of the receiver. Our study demonstrates that signaling games, which have previously been applied to economic decision-making and animal communication, provide a framework for human signaling behavior arising during sensorimotor interactions in continuous and dynamic environments. Copyright © 2015 Elsevier B.V. All rights reserved.

Social Interactions under Incomplete Information: Games, Equilibria, and Expectations

Science.gov (United States)

Yang, Chao

Interactions under Incomplete Information", is an application of the first chapter to censored outcomes, corresponding to the situation when agents" behaviors are subjected to some binding restrictions. In an interesting empirical analysis for property tax rates set by North Carolina municipal governments, it is found that there is a significant positive correlation among near-by municipalities. Additionally, some private information about its own residents is used by a municipal government to predict others' tax rates, which enriches current empirical work about tax competition. The third chapter, "Social Interactions under Incomplete Information with Multiple Equilibria", extends the first chapter by investigating effective estimation methods when the condition for a unique equilibrium may not be satisfied. With multiple equilibria, the previous model is incomplete due to the unobservable equilibrium selection. Neither conventional likelihoods nor moment conditions can be used to estimate parameters without further specifications. Although there are some solutions to this issue in the current literature, they are based on strong assumptions such as agents with the same observable characteristics play the same strategy. This paper relaxes those assumptions and extends the all-solution method used to estimate discrete choice games to a setting with both discrete and continuous choices, bounded and unbounded outcomes, and a general form of incomplete information, where the existence of a pure strategy equilibrium has been an open question for a long time. By the use of differential topology and functional analysis, it is found that when all exogenous characteristics are public information, there are a finite number of equilibria. With privately known exogenous characteristics, the equilbria can be represented by a compact set in a Banach space and be approximated by a finite set. As a result, a finite-state probability mass function can be used to specify a probability measure

Existence of three-dimensional ideal-magnetohydrodynamic equilibria with current sheets

Energy Technology Data Exchange (ETDEWEB)

Loizu, J. [Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald (Germany); Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543 (United States); Hudson, S. R.; Bhattacharjee, A.; Lazerson, S. [Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543 (United States); Helander, P. [Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald (Germany)

2015-09-15

We consider the linear and nonlinear ideal plasma response to a boundary perturbation in a screw pinch. We demonstrate that three-dimensional, ideal-MHD equilibria with continuously nested flux-surfaces and with discontinuous rotational-transform across the resonant rational-surfaces are well defined and can be computed both perturbatively and using fully nonlinear equilibrium calculations. This rescues the possibility of constructing MHD equilibria with current sheets and continuous, smooth pressure profiles. The results predict that, even if the plasma acts as a perfectly conducting fluid, a resonant magnetic perturbation can penetrate all the way into the center of a tokamak without being shielded at the resonant surface.

Nash equilibria in quantum games with generalized two-parameter strategies

International Nuclear Information System (INIS)

Flitney, Adrian P.; Hollenberg, Lloyd C.L.

2007-01-01

In the Eisert protocol for 2x2 quantum games [J. Eisert, et al., Phys. Rev. Lett. 83 (1999) 3077], a number of authors have investigated the features arising from making the strategic space a two-parameter subset of single qubit unitary operators. We argue that the new Nash equilibria and the classical-quantum transitions that occur are simply an artifact of the particular strategy space chosen. By choosing a different, but equally plausible, two-parameter strategic space we show that different Nash equilibria with different classical-quantum transitions can arise. We generalize the two-parameter strategies and also consider these strategies in a multiplayer setting

Liquids - vapor and liquids - solids equilibria in the system Th(NO3)4 - UO2(NO3)2 - HNO3 - H2O

International Nuclear Information System (INIS)

Volk, V.I.; Vakhrushin, A.Yu.; Mamaev, S.L.; Zhirnov, Yu.P.

1999-01-01

Liquids - vapor and liquids - solids equilibria in the system Th(NO 3 ) 4 - UO 2 (NO 3 ) 2 - HNO 3 - H 2 O were investigated. It was established that in this system thorium nitrate hexahydrate and uranyl nitrate hexa- and trihydrate are formed. Empiric equations of solubility isotherm at 25 deg C were found. Densities of liquid phases of the system were determined. It was established that uranyl nitrates and thorium nitrates salt out nitric acid in vapor phase just as separately so in the case of mutual presence. Empiric equation fixing relationship between nitric acid concentration in condensed phase and concentrations of all components in liquid phase was found

A partial isothermal section at 1000 ˚C of Al-Mn-Fe phase diagram in vicinity of Taylor phase and decagonal quasicrystal

Czech Academy of Sciences Publication Activity Database

Priputen, P.; Černíčková, I.; Lejček, Pavel; Janičkovič, D.; Janovec, J.

2016-01-01

Roč. 37, č. 2 (2016), 130-134 ISSN 1547-7037 R&D Projects: GA ČR GBP108/12/G043 Institutional support: RVO:68378271 Keywords : aluminium alloys * equilibria * experimental phase * intermetallics * isothermal section * phase diagram Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.938, year: 2016

Constituent phase diagrams of the Al-Cu-Fe-Mg-Ni-Si system and their application to the analysis of aluminium piston alloys

Energy Technology Data Exchange (ETDEWEB)

Belov, N.A. [Moscow Institute of Steel and Alloys, Leninsky prosp. 4, Moscow 119049 (Russian Federation); Eskin, D.G. [Netherlands Institute for Metals Research, Rotterdamseweg 137, 2628AL Delft (Netherlands)]. E-mail: deskin@nimr.nl; Avxentieva, N.N. [Moscow Institute of Steel and Alloys, Leninsky prosp. 4, Moscow 119049 (Russian Federation)

2005-10-15

The evaluation of phase equilibria in quinary systems that constitute the commercially important Al-Cu-Fe-Mg-Ni-Si alloying system is performed in the compositional range of casting alloys by means of metallography, electron probe microanalysis, X-ray diffractometry, differential scanning calorimetry, and by the analysis of phase equilibria in the constituent systems of lesser dimensionality. Suggested phase equilibria are illustrated by bi-, mono- and invariant solidification reactions, polythermal diagrams of solidification, distributions of phase fields in the solid state, and isothermal and polythermal sections. Phase composition of as-cast alloys is analyzed in terms of non-equilibrium solidification. It is shown that the increase in copper concentration in piston Al-Si alloys results in the decrease in the equilibrium solidus from 540 to 505 deg C. Under non-equilibrium solidification conditions, piston alloys finish solidification at {approx}505 deg C. Iron is bound in the quaternary Al{sub 8}FeMg{sub 3}Si{sub 6} phase in low-iron alloys and in the ternary Al{sub 9}FeNi and Al{sub 5}FeSi phases in high-iron alloys.

Deterpenation of eucalyptus essential oil by liquid + liquid extraction: Phase equilibrium and physical properties for model systems at T = 298.2 K

International Nuclear Information System (INIS)

Gonçalves, Daniel; Koshima, Cristina Chiyoda; Nakamoto, Karina Thiemi; Umeda, Thayla Karla; Aracava, Keila Kazue; Gonçalves, Cintia Bernardo; Rodrigues, Christianne Elisabete da Costa

2014-01-01

Highlights: • Fractionation of essential oil compounds. • Liquid + liquid equilibria of limonene, citronellal, ethanol and water were studied. • Distribution coefficients of limonene and citronellal were evaluated. • Densities and viscosities of the phases were experimentally determined. • Solvent selectivities and physical properties were dependent on citronellal and water mass fractions. -- Abstract: As the principal source in Brazil of eucalyptus essential oil extracts, Eucalyptus citriodora contains citronellal, an oxygenated compound responsible for the flavour characteristics. Deterpenation processes, consisting of the removal of terpenic hydrocarbons with the subsequent concentration of the oxygenated compounds, can be used to improve the aromatic characteristics of this essential oil. The purpose of this work was to perform a study of the technical feasibility of using a liquid + liquid extraction process to deterpenate eucalyptus essential oil. Model systems with various mixtures of limonene and citronellal (representing eucalyptus essential oil) as well as solvent (ethanol with various water mass fractions) were used to obtain liquid + liquid equilibrium data. The raffinate and extract phases were also analyzed to characterize the physical properties (density and viscosity). The equilibrium data were used to adjust the NRTL and UNIQUAC parameters. Two empirical models, the simple mixing rule and the Grunberg–Nissan model, were evaluated for use in the descriptions of the densities and viscosities, respectively, of the samples. Increasing the water content in the solvent resulted in decreases in the limonene and citronellal distribution coefficients, with consequential increases in the solvent selectivity values. Increasing values of the densities and viscosities, especially for the solvent-rich phases, were associated with systems using high amounts of hydrated ethanolic solvents

Density-functional study on the equilibria in the ThDP activation.

Science.gov (United States)

Delgado, Eduardo J; Alderete, Joel B; Jaña, Gonzalo A

2011-11-01

The equilibria among the various ionization and tautomeric states involved in the activation of ThDP is addressed using high level density functional theory calculations, X3LYP/6-311++G(d,p)//X3LYP(PB)/6-31++G(d,p). This study provides the first theoretically derived thermodynamic data for the internal equilibria in the activation of ThDP. The role of the medium polarity on the geometry and thermodynamics of the diverse equilibria of ThDP is addressed. The media chosen are cyclohexane and water, as paradigms of apolar and polar media. The results suggest that all ionization and tautomeric states are accessible during the catalytic cycle, even in the absence of substrate, being APH(+) the form required to interconvert the AP and IP tautomers; and the generation of the ylide proceeds via the formation of the IP form. Additionally, the calculated ΔG° values allow to calculate all the equilibrium constants, including the pK(C2) for the thiazolium C2 atom whose ionization is believed to initiate the catalytic cycle.

Global attractor and asymptotic dynamics in the Kuramoto model for coupled noisy phase oscillators

International Nuclear Information System (INIS)

Giacomin, Giambattista; Pakdaman, Khashayar; Pellegrin, Xavier

2012-01-01

We study the dynamics of the large N limit of the Kuramoto model of coupled phase oscillators, subject to white noise. We introduce the notion of shadow inertial manifold and we prove their existence for this model, supporting the fact that the long-term dynamics of this model is finite dimensional. Following this, we prove that the global attractor of this model takes one of two forms. When coupling strength is below a critical value, the global attractor is a single equilibrium point corresponding to an incoherent state. Otherwise, when coupling strength is beyond this critical value, the global attractor is a two-dimensional disc composed of radial trajectories connecting a saddle-point equilibrium (the incoherent state) to an invariant closed curve of locally stable equilibria (partially synchronized state). Our analysis hinges, on the one hand, upon sharp existence and uniqueness results and their consequence for the existence of a global attractor, and, on the other hand, on the study of the dynamics in the vicinity of the incoherent and coherent (or synchronized) equilibria. We prove in particular nonlinear stability of each synchronized equilibrium, and normal hyperbolicity of the set of such equilibria. We explore mathematically and numerically several properties of the global attractor, in particular we discuss the limit of this attractor as noise intensity decreases to zero

Computation of tokamak equilibria with steady flow

International Nuclear Information System (INIS)

Kerner, W.; Tokuda, Shinji

1987-08-01

The equations for ideal MHD equilibria with stationary flow are reexamined and addressed as numerically applied to tokamak configurations with a free plasma boundary. Both the isothermal (purely toroidal flow) and the poloidal flow cases are treated. Experiment-relevant states with steady flow (so far only in the toroidal direction) are computed by the modified SELENE40 code. (author)

Lagrangian relative equilibria for a gyrostat in the three-body problem: bifurcations and stability

Energy Technology Data Exchange (ETDEWEB)

Guirao, Juan L G; Vera, Juan A, E-mail: juan.garcia@upct.e, E-mail: juanantonio.vera@upct.e [Departamento de Matematica Aplicada y EstadIstica, Universidad Politecnica de Cartagena, Hospital de Marina, 30203 Cartagena, Region de Murcia (Spain)

2010-05-14

In this paper we consider the non-canonical Hamiltonian dynamics of a gyrostat in the frame of the three-body problem. Using geometric/mechanic methods we study the approximate dynamics of the truncated Legendre series representation of the potential of an arbitrary order. Working in the reduced problem, we study the existence of relative equilibria that we refer to as Lagrange type following the analogy with the standard techniques. We provide necessary and sufficient conditions for the linear stability of Lagrangian relative equilibria if the gyrostat morphology form is close to a sphere. Thus, we generalize the classical results on equilibria of the three-body problem and many results on them obtained by the classic approach for the case of rigid bodies.

Microstructure and mechanical properties of Mg-Zn-Y alloy containing LPSO phase and I-phase

Science.gov (United States)

Ye, Zhijian; Teng, Xinying; Lou, Gui; Zhou, Guorong; Leng, Jinfeng

2017-08-01

Microstructure and mechanical properties of Mg-Zn-Y alloy including LPSO phase and I-phase was investigated. Transmission electron microscopy, x-ray diffraction analysis and differential scanning calorimeter analysis reveal that the LPSO (long period stacking ordered structure) phase and I-phase can co-exist within the α-Mg matrix. Wherein, the quasicrystal phases exist in the (I-phase  +  α-Mg) eutectic structures. In the Mg-Zn-Y alloy, it is also found that 14 H type LPSO phases consist of LPSO phase and I-phase. With the addition of quasicrystal master alloy content, the microstructures are refined, and the mechanical properties are enhanced.

(Vapour + liquid) equilibria for (2,2-dimethoxypropane + methanol) and (2,2-dimethoxypropane + acetone)

International Nuclear Information System (INIS)

Jiang Hui; Li Haoran; Wang Congmin; Tan Taijun; Han Shijun

2003-01-01

The isothermal and isobaric (vapour + liquid) equilibria for (2,2-dimethoxypropane + methanol) and (2,2-dimethoxypropane + acetone) measured with an inclined ebulliometer are presented. The experimental results are analysed using the UNIQUAC equation with the temperature-dependent binary parameters with satisfactory results. Isobaric (vapour + liquid) equilibria data for these systems at p=99.99 kPa are compared with the literature data. Experimental vapour pressure of 2,2-dimethoxypropane are also included

Phase equilibria of binary mixtures by molecular simulation and cubic equations of state

Directory of Open Access Journals (Sweden)

Cabral V.F.

2001-01-01

Full Text Available Molecular simulation data were used to study the performance of equations of state (EoS and combining rules usually employed in thermodynamic property calculations. The Monte Carlo method and the Gibbs ensemble technique were used for determining composition and densities of vapor and liquid phases in equilibrium for binary mixtures of Lennard-Jones fluids. Simulation results are compared to data in the literature and to those calculated by the t-PR-LJ EoS. The use of adequate combining rules has been shown to be very important for the satisfactory representation of molecular simulation data.

Critical point analysis of phase envelope diagram

International Nuclear Information System (INIS)

Soetikno, Darmadi; Siagian, Ucok W. R.; Kusdiantara, Rudy; Puspita, Dila; Sidarto, Kuntjoro A.; Soewono, Edy; Gunawan, Agus Y.

2014-01-01

Phase diagram or phase envelope is a relation between temperature and pressure that shows the condition of equilibria between the different phases of chemical compounds, mixture of compounds, and solutions. Phase diagram is an important issue in chemical thermodynamics and hydrocarbon reservoir. It is very useful for process simulation, hydrocarbon reactor design, and petroleum engineering studies. It is constructed from the bubble line, dew line, and critical point. Bubble line and dew line are composed of bubble points and dew points, respectively. Bubble point is the first point at which the gas is formed when a liquid is heated. Meanwhile, dew point is the first point where the liquid is formed when the gas is cooled. Critical point is the point where all of the properties of gases and liquids are equal, such as temperature, pressure, amount of substance, and others. Critical point is very useful in fuel processing and dissolution of certain chemicals. Here in this paper, we will show the critical point analytically. Then, it will be compared with numerical calculations of Peng-Robinson equation by using Newton-Raphson method. As case studies, several hydrocarbon mixtures are simulated using by Matlab

Critical point analysis of phase envelope diagram

Energy Technology Data Exchange (ETDEWEB)

Soetikno, Darmadi; Siagian, Ucok W. R. [Department of Petroleum Engineering, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Kusdiantara, Rudy, E-mail: rkusdiantara@s.itb.ac.id; Puspita, Dila, E-mail: rkusdiantara@s.itb.ac.id; Sidarto, Kuntjoro A., E-mail: rkusdiantara@s.itb.ac.id; Soewono, Edy; Gunawan, Agus Y. [Department of Mathematics, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

2014-03-24

Phase diagram or phase envelope is a relation between temperature and pressure that shows the condition of equilibria between the different phases of chemical compounds, mixture of compounds, and solutions. Phase diagram is an important issue in chemical thermodynamics and hydrocarbon reservoir. It is very useful for process simulation, hydrocarbon reactor design, and petroleum engineering studies. It is constructed from the bubble line, dew line, and critical point. Bubble line and dew line are composed of bubble points and dew points, respectively. Bubble point is the first point at which the gas is formed when a liquid is heated. Meanwhile, dew point is the first point where the liquid is formed when the gas is cooled. Critical point is the point where all of the properties of gases and liquids are equal, such as temperature, pressure, amount of substance, and others. Critical point is very useful in fuel processing and dissolution of certain chemicals. Here in this paper, we will show the critical point analytically. Then, it will be compared with numerical calculations of Peng-Robinson equation by using Newton-Raphson method. As case studies, several hydrocarbon mixtures are simulated using by Matlab.

Development of long-lived radionuclides partitioning technology - Experimental/theoretical study of phase equilibria for multicomponent multiphase systems

Energy Technology Data Exchange (ETDEWEB)

Lee, Chul Soo; Lee, Se Il; Sim, Yeon Sik; Park, Sung Bin; Yang, Sung Oh; Park, Ji Yong [Korea University, Seoul (Korea, Republic of)

1995-08-01

In various partitioning processes, rare earth elements and actinide elements are separated from other elements in the first stage. They are then separated into rare earth groups and actinde groups. The first stage is accomplished by solvent extraction using DEHPA, by precipitation using oxalic= acid, or by cation exchange. The second stage is carried out by selective back-extraction or by selective elution using DTPA. In these processes the equilibria is governed by the concentrations of nitric acid, of solvents, and of precipitants among others. In this study various distribution coefficients in partitioning processes were experimentally determined. And thermodynamic models were proposed to calculate distribution coefficients with experimentally determined equilibrium constants. 32 refs., 11 tabs., 23 figs. (author)

Investigations of (acid+base) equilibria in systems modelling interactions occurring in biomolecules

Energy Technology Data Exchange (ETDEWEB)

Kozak, Anna [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Czaja, Malgorzata [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, Lech [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)]. E-mail: lech@chem.univ.gda.pl

2006-05-15

By using the potentiometric microtitration method, acidity constants, K{sub a}, anionic, K{sub AHA{sup -}}, and cationic, K{sub BHB{sup +}}, homoconjugation constants, as well as molecular heteroconjugation, K{sub BHA}, constants have been determined in (acid+base) systems formed by the following compounds: acetic acid, phenol, n-butylamine, imidazole, and 4(5)-methylimidazole. These compounds constitute fragments of the side chains of amino acids capable of proton exchange in active sites of enzymes. The (acid+base) equilibria were studied in five polar solvents of different properties, namely in aprotic protophobic acetonitrile, acetone and propylene carbonate, in aprotic protophilic dimethyl sulfoxide and in amphiprotic methanol. The lowest values of the acidity constants of the molecular and cationic acids have been found in aprotic protophobic polar solvents - acetonitrile, propylene carbonate and acetone. Their acid strength have been found to depend on solvent basicity expressed as donor numbers, DN. These media, in particular acetonitrile and acetone, are also favourable for establishing molecular homo- and heteroconjugation equilibria. The most stable homocomplexes are formed in the case of acetic acid (K{sub AHA{sup -}} values range from 2.26 to 3.56 in these media, being more than an order of magnitude higher than those for the remaining compounds). The magnitudes of lgK{sub BHA} reveal that the most stable heterocomplexes are formed by n-butylamine and acetic acid that are characterized by the smallest differences in pK{sub a} values.

From Singularity Theory to Finiteness of Walrasian Equilibria

DEFF Research Database (Denmark)

Castro, Sofia B.S.D.; Dakhlia, Sami F.; Gothen, Peter

The paper establishes that for an open and dense subset of smooth exchange economies, the number of Walrasian equilibria is finite. In particular, our results extend to non-regular economies; it even holds when restricted to the subset of critical ones. The proof rests on concepts from singularity...... theory....

Generalized thermodynamics of phase equilibria in scalar active matter

Science.gov (United States)

Solon, Alexandre P.; Stenhammar, Joakim; Cates, Michael E.; Kafri, Yariv; Tailleur, Julien

2018-02-01

Motility-induced phase separation (MIPS) arises generically in fluids of self-propelled particles when interactions lead to a kinetic slowdown at high densities. Starting from a continuum description of scalar active matter akin to a generalized Cahn-Hilliard equation, we give a general prescription for the mean densities of coexisting phases in flux-free steady states that amounts, at a hydrodynamics scale, to extremizing an effective free energy. We illustrate our approach on two well-known models: self-propelled particles interacting either through a density-dependent propulsion speed or via direct pairwise forces. Our theory accounts quantitatively for their phase diagrams, providing a unified description of MIPS.

Thermal analysis, phase equilibria, and superconducting properties in magnesium boride and carbon doped magnesium boride

Science.gov (United States)

Bohnenstiehl, Scot David

In this work, the low temperature synthesis of MgB2 from Mg/B and MgH2/B powder mixtures was studied using Differential Scanning Calorimetry (DSC). For the Mg/B powder mixture, two exothermic reaction events were observed and the first reaction event was initiated by the decomposition of Mg(OH)2 on the surface of the magnesium powder. For the MgH 2/B powder mixture, there was an endothermic event at ˜375 °C (the decomposition of MgH2 into H2 and Mg) and an exothermic event ˜600 °C (the reaction of Mg and B). The Kissinger analysis method was used to estimate the apparent activation energy of the Mg and B reaction using DSC data with different furnace ramp rates. The limitations of MgB2 low temperature synthesis led to the development of a high pressure induction furnace that was constructed using a pressure vessel and an induction heating power supply. The purpose was to not only synthesize more homogeneous MgB2 samples, but also to determine whether MgB2 melts congruently or incongruently. A custom implementation of the Smith Thermal Analysis method was developed and tested on aluminum and AlB2, the closest analogue to MgB2. Measurements on MgB2 powder and a high purity Mg/B elemental mixture confirmed that MgB2 melts incongruently and decomposes into a liquid and MgB4 at ˜1445 °C at 10 MPa via peritectic decomposition. Another measurement using a Mg/B elemental mixture with impure boron suggested that ˜0.7 wt% carbon impurity in the boron raised the incongruent melting temperature to ˜1490-1500 °C. Lastly, the solubility limit for carbon in MgB2 was studied by making samples from B4C and Mg at 1530 °C, 1600 °C and 1700 °C in the high pressure furnace. All three samples had three phases: Mg, MgB2C2, and carbon doped MgB2. The MgB 2C2 and carbon doped MgB2 grain size increased with temperature and the 1700 °C sample had needle-like grains for both phases. The presence of the ternary phase, MgB2C2, suggested that the maximum doping limit for carbon in

A stable algorithm for calculating phase equilibria with capillarity at specified moles, volume and temperature using a dynamic model

KAUST Repository

Kou, Jisheng

2017-09-30

Capillary pressure can significantly affect the phase properties and flow of liquid-gas fluids in porous media, and thus, the phase equilibrium calculation incorporating capillary pressure is crucial to simulate such problems accurately. Recently, the phase equilibrium calculation at specified moles, volume and temperature (NVT-flash) becomes an attractive issue. In this paper, capillarity is incorporated into the phase equilibrium calculation at specified moles, volume and temperature. A dynamical model for such problem is developed for the first time by using the laws of thermodynamics and Onsager\\'s reciprocal principle. This model consists of the evolutionary equations for moles and volume, and it can characterize the evolutionary process from a non-equilibrium state to an equilibrium state in the presence of capillarity effect at specified moles, volume and temperature. The phase equilibrium equations are naturally derived. To simulate the proposed dynamical model efficiently, we adopt the convex-concave splitting of the total Helmholtz energy, and propose a thermodynamically stable numerical algorithm, which is proved to preserve the second law of thermodynamics at the discrete level. Using the thermodynamical relations, we derive a phase stability condition with capillarity effect at specified moles, volume and temperature. Moreover, we propose a stable numerical algorithm for the phase stability testing, which can provide the feasible initial conditions. The performance of the proposed methods in predicting phase properties under capillarity effect is demonstrated on various cases of pure substance and mixture systems.

Molecular thermodynamics using fluctuation solution theory

DEFF Research Database (Denmark)

Ellegaard, Martin Dela

. The framework relates thermodynamic variables to molecular pair correlation functions of liquid mixtures. In this thesis, application of the framework is illustrated using two approaches: 1. Solubilities of solid solutes in mixed solvent systems are determined from fluctuation solution theory application......Properties of chemicals and their mutual phase equilibria are critical variables in process design. Reliable estimates of relevant equilibrium properties, from thermodynamic models, can form the basis of good decision making in the development phase of a process design, especially when access...... to relevant experimental data is limited. This thesis addresses the issue of generating and using simple thermodynamic models within a rigorous statistical mechanical framework, the so-called fluctuation solution theory, from which relations connecting properties and phase equilibria can be obtained...

Close pairs of relative equilibria for identical point vortices

DEFF Research Database (Denmark)

Dirksen, Tobias; Aref, Hassan

2011-01-01

Numerical solution of the classical problem of relative equilibria for identical point vortices on the unbounded plane reveals configurations that are very close to the analytically known, centered, symmetrically arranged, nested equilateral triangles. New numerical solutions of this kind are fou...

Equilibria of perceptrons for simple contingency problems.

Science.gov (United States)

Dawson, Michael R W; Dupuis, Brian

2012-08-01

The contingency between cues and outcomes is fundamentally important to theories of causal reasoning and to theories of associative learning. Researchers have computed the equilibria of Rescorla-Wagner models for a variety of contingency problems, and have used these equilibria to identify situations in which the Rescorla-Wagner model is consistent, or inconsistent, with normative models of contingency. Mathematical analyses that directly compare artificial neural networks to contingency theory have not been performed, because of the assumed equivalence between the Rescorla-Wagner learning rule and the delta rule training of artificial neural networks. However, recent results indicate that this equivalence is not as straightforward as typically assumed, suggesting a strong need for mathematical accounts of how networks deal with contingency problems. One such analysis is presented here, where it is proven that the structure of the equilibrium for a simple network trained on a basic contingency problem is quite different from the structure of the equilibrium for a Rescorla-Wagner model faced with the same problem. However, these structural differences lead to functionally equivalent behavior. The implications of this result for the relationships between associative learning, contingency theory, and connectionism are discussed.

The effect of zinc on the microstructure and phase transformations of casting Al-Cu alloys

Directory of Open Access Journals (Sweden)

Manasijević Ivana I.

2016-01-01

Full Text Available Copper is one of the main alloying elements for aluminum casting alloys. As an alloying element, copper significantly increases the tensile strength and toughness of alloys based on aluminum. The copper content in the industrial casting aluminum alloys ranges from 3,5 to 11 wt.%. However, despite the positive effect on the mechanical properties, copper has a negative influence on the corrosion resistance of aluminum and its alloys. In order to further improve the properties of Al-Cu alloys they are additional alloyed with elements such as zinc, magnesium and others. In this work experimental and analytical examination of the impact of zinc on the microstructure and phase transformations of Al-Cu alloys was carried out. In order to determine the effect of the addition of zinc to the structure and phase transformations of Al-Cu alloys two alloys of Al-Cu-Zn system with selected compositions were prepared and then examined using scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDX. The experimental results were compared with the results of thermodynamic calculations of phase equilibria.

Novel monoclinic zirconolite in Bi2O3–CuO–Ta2O5 ternary system: Phase equilibria, structural and electrical properties

International Nuclear Information System (INIS)

Tan, K.B.; Chon, M.P.; Khaw, C.C.; Zainal, Z.; Taufiq Yap, Y.H.; Tan, P.Y.

2014-01-01

Highlights: • Novel BCT monoclinic zirconolite phase was prepared through solid state reaction. • Comprehensive study of reaction mechanism was performed by careful firing control. • Qualitative structural and phase analyses were conducted. • Electrical response in broad range of temperature and frequency was investigated. - Abstract: Synthesis of novel monoclinic zirconolite, Bi 1.92 Cu 0.08 (Cu 0.3 Ta 0.7 ) 2 O 7.06 (β-BCT) using solid state reaction had been finalised at the firing temperature of 900 °C over 24 h. The X–ray diffraction pattern of β-BCT was fully indexed on a monoclinic symmetry, space group, C2/c with lattice constants, a = 13.1052 (8), b = 7.6749 (5), c = 12.162 (6), α = γ = 90° and β = 101.32° (1), respectively. The reaction mechanism study indicated phase formation was greatly influenced by the reaction between intermediate bismuth tantalate binary phases and CuO at elevated temperatures. β-BCT was thermally stable up to a temperature of 900 °C and contained spherulite grains with sizes ranging from 1 to 14 μm. Electrical properties of this material were characterised over a broad temperature range covering temperatures from 10 K to 874 K. At the temperature of 304 K, two semicircles were discernible in complex Cole–Cole plot showing an insulating grain boundary with C gb = 6.63 × 10 −9 F cm −1 and a bulk response capacitance, C b = 6.74 × 10 −12 F cm −1 . The Power law frequency-dependent ac conductivity of β-BCT was apparent in three frequency regimes; a low–frequency plateau regime, a high-frequency plateau regime and a dispersive regime taking place in the temperature range of 220–576 K. The frequency-dependent ac conductivity of β-BCT with increasing temperature was attributed to the thermal activated electrical conduction mechanism within the structure

Kinetic stability constraints on magnetized plasma equilibria: Quasi-particle approach

International Nuclear Information System (INIS)

Sosenko, P.; Weiland, J.

1996-01-01

Macroscopic adiabatic invariants for the magnetized plasma are studied within the context of the quasi-particle description, as well as constraints which they impose on energy transfer and stable plasma equilibria. 6 refs

A periodic point-based method for the analysis of Nash equilibria in 2 x 2 symmetric quantum games

International Nuclear Information System (INIS)

Schneider, David

2011-01-01

We present a novel method of looking at Nash equilibria in 2 x 2 quantum games. Our method is based on a mathematical connection between the problem of identifying Nash equilibria in game theory, and the topological problem of the periodic points in nonlinear maps. To adapt our method to the original protocol designed by Eisert et al (1999 Phys. Rev. Lett. 83 3077-80) to study quantum games, we are forced to extend the space of strategies from the initial proposal. We apply our method to the extended strategy space version of the quantum Prisoner's dilemma and find that a new set of Nash equilibria emerge in a natural way. Nash equilibria in this set are optimal as Eisert's solution of the quantum Prisoner's dilemma and include this solution as a limit case.

Phase Equilibria of Mixtures Containing Organic Sulfur Species (OSS) and Water/Hydrocarbons: VLE Measurements and Modeling Using the Cubic-Plus-Association Equation of State

DEFF Research Database (Denmark)

Awan, Javeed; Tsivintzelis, Ioannis; Breil, Martin

2010-01-01

with the cubic-plus-association (CPA) equation of state. Useful remarks are presented about the application of Henry’s constant values to estimate binary interaction parameters of the CPA EoS for the description of whole vapor−liquid equilibria. The results using CPA EoS show that the cross association...

Liquid–liquid equilibria in the quinary aqueous two-phase system of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol: Experimental investigation and thermodynamic modeling

Energy Technology Data Exchange (ETDEWEB)

Hekayati, Javad; Roosta, Aliakbar, E-mail: aa.roosta@sutech.ac.ir; Javanmardi, Jafar

2016-02-10

Highlights: • Quinary LLE phase equilibria involving PEG 6000 + Na{sub 2}SO{sub 4} + H{sub 2}O + glucose + ethanol. • Favorable partition coefficients of ethanol and glucose. • Satisfactory correlation of the LLE experimental data with the original NRTL model. • Root mean squared deviations (RMSDs) of less than 0.6%. - Abstract: Extractive fermentation processes involving aqueous two-phase systems (ATPSs) are considered as viable means of overcoming the problems associated with product inhibition. Practical development of these processes requires accurate knowledge of the liquid–liquid equilibrium (LLE) of the ATPS forming components alongside the substrate and product of the fermentation process. In this work, the quinary aqueous two-phase LLE of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol have been experimentally determined at 298.15 K using spectrophotometric methods. The resulting LLE data were then satisfactorily correlated by the non-random two-liquid (NRTL) activity coefficient model based on mass fractions. In doing so, the binary energy interaction parameters of the NRTL activity coefficient model were obtained and reported. Calculated RMS deviations below 0.6% demonstrate that the original NRTL activity coefficient model can accurately correlate the LLE data of the quinary aqueous biphasic system of interest.

Liquid–liquid equilibria in the quinary aqueous two-phase system of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol: Experimental investigation and thermodynamic modeling

International Nuclear Information System (INIS)

Hekayati, Javad; Roosta, Aliakbar; Javanmardi, Jafar

2016-01-01

Highlights: • Quinary LLE phase equilibria involving PEG 6000 + Na_2SO_4 + H_2O + glucose + ethanol. • Favorable partition coefficients of ethanol and glucose. • Satisfactory correlation of the LLE experimental data with the original NRTL model. • Root mean squared deviations (RMSDs) of less than 0.6%. - Abstract: Extractive fermentation processes involving aqueous two-phase systems (ATPSs) are considered as viable means of overcoming the problems associated with product inhibition. Practical development of these processes requires accurate knowledge of the liquid–liquid equilibrium (LLE) of the ATPS forming components alongside the substrate and product of the fermentation process. In this work, the quinary aqueous two-phase LLE of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol have been experimentally determined at 298.15 K using spectrophotometric methods. The resulting LLE data were then satisfactorily correlated by the non-random two-liquid (NRTL) activity coefficient model based on mass fractions. In doing so, the binary energy interaction parameters of the NRTL activity coefficient model were obtained and reported. Calculated RMS deviations below 0.6% demonstrate that the original NRTL activity coefficient model can accurately correlate the LLE data of the quinary aqueous biphasic system of interest.

Extensive Study of the Capabilities and Limitations of the CPA and sPC-SAFT Equations of State in Modeling a Wide Range of Acetic Acid Properties

DEFF Research Database (Denmark)

Ribeiro, Rafael T. C. S.; Alberton, André L.; Paredes, Márcio L. L.

2018-01-01

pressure and density. Other important properties, such as the speed of sound, second virial coefficient, compressibility factor, enthalpy of vaporization, and isobaric heat capacity have not been considered yet. Few studies investigate which is the appropriate association scheme to be used for acetic acid...... of state, e.g., those belonging to the statistical associating fluid theory (SAFT) family. While several researchers have studied the use of SAFT variants to model acetic acid properties (pure compound and mixtures), with few exceptions, those studies focused exclusively on phase equilibria including vapor...

Boron incorporation into rutile: phase equilibria and structural considerations

Energy Technology Data Exchange (ETDEWEB)

Grey, I.E.; Li, C.; MacRae, C.M. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), East Melbourne, VIC (Australia). Div of Minerals; Bursill, L.A. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

1997-06-01

Reduction of rutile in the presence of borate flux stabilised the rutile phase relative to reduced rutiles due to incorporation of boron from the flux. In the presence of borates the rutile phase is stabilised to oxygen fugacities that are lower by almost two orders of magnitude compared with fugacities at the limit of the single-phase rutile phase field in the pure Ti-O system. Boron incorporation is accompanied by reduction of titanium to the trivalent state, according to the charge compensation relation: 3Ti{sup 4+}{identical_to} 3 Ti{sup 3+} + B{sup 3+}. Results of powder X-ray diffraction and transmission electron microscopy studies on samples prepared in the temperature range 1100 to 1300 deg C have been used to establish a model for boron incorporation. It is proposed that at the temperatures studied, local defects in boron doped rutile result from displacement of titanium atoms to adjacent interstitial sites coupled with occupation by boron of the triangular face of the vacated octahedral sites. This atomic grouping represents a small element of the TiBO{sub 3} (calcite-type) structure. Annealing at a lower temperature results in ordering of the local defects to form (101){sub r} planar intergrowths of rutile and calcite-type structures. 14 refs., 3 tabs., 8 figs.

Boron incorporation into rutile: phase equilibria and structural considerations

International Nuclear Information System (INIS)

Grey, I.E.; Li, C.; MacRae, C.M.; Bursill, L.A.

1997-01-01

Reduction of rutile in the presence of borate flux stabilised the rutile phase relative to reduced rutiles due to incorporation of boron from the flux. In the presence of borates the rutile phase is stabilised to oxygen fugacities that are lower by almost two orders of magnitude compared with fugacities at the limit of the single-phase rutile phase field in the pure Ti-O system. Boron incorporation is accompanied by reduction of titanium to the trivalent state, according to the charge compensation relation: 3Ti 4+ ≡ 3 Ti 3+ + B 3+ . Results of powder X-ray diffraction and transmission electron microscopy studies on samples prepared in the temperature range 1100 to 1300 deg C have been used to establish a model for boron incorporation. It is proposed that at the temperatures studied, local defects in boron doped rutile result from displacement of titanium atoms to adjacent interstitial sites coupled with occupation by boron of the triangular face of the vacated octahedral sites. This atomic grouping represents a small element of the TiBO 3 (calcite-type) structure. Annealing at a lower temperature results in ordering of the local defects to form (101) r planar intergrowths of rutile and calcite-type structures. 14 refs., 3 tabs., 8 figs

On pure-strategy Nash equilibria in price-quantity games

NARCIS (Netherlands)

Bos, I.; Vermeulen, A.J.

2015-01-01

This paper examines the existence and characteristics of pure-strategy Nash equilibria in oligopoly models in which firms set both prices and quantities. Existence is proved for a broad and natural class of price-quantity games. With differentiated products, the equilibrium outcome is similar to

Positivity properties of phase-plane distribution functions

NARCIS (Netherlands)

Janssen, A.J.E.M.

1984-01-01

The aim of this paper is to compare the members of Cohen's class of phase-plane distributions with respect to positivity properties. It is known that certain averages (which are in a sense compatible with Heisenberg's uncertainty principle) of the Wigner distribution over the phase-plane yield

Theoretical models of non-Maxwellian equilibria for one-dimensional collisionless plasmas

Science.gov (United States)

Allanson, O.; Neukirch, T.; Wilson, F.; Troscheit, S.

2016-12-01

It is ideal to use exact equilibrium solutions of the steady state Vlasov-Maxwell system to intialise collsionless simulations. However, exact equilibrium distribution functions (DFs) for a given macroscopic configuration are typically unknown, and it is common to resort to using `flow-shifted' Maxwellian DFs in their stead. These DFs may be consistent with a macrosopic system with the target number density and current density, but could well have inaccurate higher order moments. We present recent theoretical work on the `inverse problem in Vlasov-Maxwell equilibria', namely calculating an exact solution of the Vlasov equation for a specific given magnetic field. In particular, we focus on one-dimensional geometries in Cartesian (current sheets) coordinates.1. From 1D fields to Vlasov equilibria: Theory and application of Hermite Polynomials: (O. Allanson, T. Neukirch, S. Troscheit and F. Wilson, Journal of Plasma Physics, 82, 905820306 (2016) [28 pages, Open Access] )2. An exact collisionless equilibrium for the Force-Free Harris Sheet with low plasma beta: (O. Allanson, T. Neukirch, F. Wilson and S. Troscheit, Physics of Plasmas, 22, 102116 (2015) [11 pages, Open Access])3. Neutral and non-neutral collisionless plasma equilibria for twisted flux tubes: The Gold-Hoyle model in a background field (O. Allanson, F. Wilson and T. Neukirch, (2016)) (accepted, Physics of Plasmas)

A study of electron-positron pair equilibria in models of compact X- and gamma-ray sources

International Nuclear Information System (INIS)

Bjoernsson, G.

1990-01-01

Thermal electron-positron pair equilibria in two temperature models of compact x ray and gamma ray sources are studied. The pairs are assumed to be heated by Coulomb interaction with the much hotter protons and cooled by bremsstrahlung emission, Compton scattering, and annihilation. Two parameters, the proton optical depth and the compactness, characterize each equilibrium state. It is shown that a careful account of the energy balance is very important when the stability properties of the pair equilibria in a spherical plasma cloud are determined. The equilibria are found to be unstable in a very limited range of compactness and proton optical depth. This particular instability is unlikely to be the cause of the observed variability of the compact sources and implies that it is possible to build up high pair densities by a thermal mechanism in two temperature environments. The most important result considers the effects of pairs on the structure of geometrically and effectively optically thin accretion disks. A new approach for solving for the equilibrium structure of the disks is presented. In effect, the pair equilibrium states are projected into the space spanned by the disk structure parameters. This allows a direct visualization of all possible disk solutions at once. Each solution profile needs to be calculated only once and a complete disk solution is obtained by a simple radial coordinate transformation. The disk solutions are thus seen to be scale free in terms of the radial coordinate as well as in terms of the mass of the central object and the accretion rate. Two particular disk solutions are given. It is shown that including electron-positron pairs in the disk structure calculations leads to a breakdown of the thin disk assumptions and that more detailed disk modeling is required before electron-positron pairs can be self-consistently included

A periodic point-based method for the analysis of Nash equilibria in 2 x 2 symmetric quantum games

Energy Technology Data Exchange (ETDEWEB)

Schneider, David, E-mail: schneide@tandar.cnea.gov.ar [Departamento de Fisica, Comision Nacional de EnergIa Atomica. Av. del Libertador 8250, 1429 Buenos Aires (Argentina)

2011-03-04

We present a novel method of looking at Nash equilibria in 2 x 2 quantum games. Our method is based on a mathematical connection between the problem of identifying Nash equilibria in game theory, and the topological problem of the periodic points in nonlinear maps. To adapt our method to the original protocol designed by Eisert et al (1999 Phys. Rev. Lett. 83 3077-80) to study quantum games, we are forced to extend the space of strategies from the initial proposal. We apply our method to the extended strategy space version of the quantum Prisoner's dilemma and find that a new set of Nash equilibria emerge in a natural way. Nash equilibria in this set are optimal as Eisert's solution of the quantum Prisoner's dilemma and include this solution as a limit case.

Asset pricing puzzles explained by incomplete Brownian equilibria

DEFF Research Database (Denmark)

Christensen, Peter Ove; Larsen, Kasper

We examine a class of Brownian based models which produce tractable incomplete equilibria. The models are based on finitely many investors with heterogeneous exponential utilities over intermediate consumption who receive partially unspanned income. The investors can trade continuously on a finit...... markets. Consequently, our model can simultaneously help explaining the risk-free rate and equity premium puzzles....

The Potential of Soave-Redlich-Kwong Equation of State in Describing Phase Equilibria Data at High Pressures for the CO2 + 1-Alcohol Systems

Czech Academy of Sciences Publication Activity Database

Teodorescu, M.; Barhala, A.; Wichterle, Ivan

2005-01-01

Roč. 49, č. 11 (2005), s. 927-934 ISSN 0035-3930 R&D Projects: GA ČR(CZ) GA104/03/1555; GA AV ČR(CZ) IAA4072102 Institutional research plan: CEZ:AV0Z40720504 Keywords : vapor liquid equilibria * description Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.226, year: 2005

Thermodynamic Property Model of Wide-Fluid Phase Propane

Directory of Open Access Journals (Sweden)

I Made Astina

2007-05-01

Full Text Available A new thermodynamic property model for propane is expressed in form of the Helmholtz free energy function. It consists of eight terms of the ideal-gas part and eighteen terms of the residual part. Accurate experimental data of fluid properties and theoretical approach from the intermolecular potential were simultaneously considered in the development to insure accuracy and to improve reliability of the equation of state over wide range of pressures and temperatures. Based on the state range of experimental data used in the model development, the validity range is judged from the triple-point of 85.48 K to temperature of 450 K and pressure up to 60 MPa. The uncertainties with respect to different properties are estimated to be 0.03% in ideal-gas isobaric specific heat, 0.2% in liquid phase density, 0.3% in gaseous phase density 1% in specific heats, 0.1% in vapor-pressure except at very low temperatures, 0.05% in saturated-liquid density, 0.02% in speed of sound of the gaseous phase and 1% in speed of sound of the liquid phase.

ThermoData Engine: Extension to Solvent Design and Multi-component Process Stream Property Calculations with Uncertainty Analysis

DEFF Research Database (Denmark)

Diky, Vladimir; Chirico, Robert D.; Muzny, Chris

ThermoData Engine (TDE, NIST Standard Reference Databases 103a and 103b) is the first product that implements the concept of Dynamic Data Evaluation in the fields of thermophysics and thermochemistry, which includes maintaining the comprehensive and up-to-date database of experimentally measured...... property values and expert system for data analysis and generation of recommended property values at the specified conditions along with uncertainties on demand. The most recent extension of TDE covers solvent design and multi-component process stream property calculations with uncertainty analysis...... variations). Predictions can be compared to the available experimental data, and uncertainties are estimated for all efficiency criteria. Calculations of the properties of multi-component streams including composition at phase equilibria (flash calculations) are at the heart of process simulation engines...

Geological constraints on the thermodynamic properties of the stilbite - stellerite solid solution in low-grade metabasalts

Science.gov (United States)

Fridriksson, Thráinn; Neuhoff, Philip S.; Arnórsson, Stefán; Bird, Dennis K.

2001-11-01

Standard state thermodynamic data for stilbite (Ca2NaAl5Si13O36∗16H2O) and stellerite (Ca2Al4Si14O36∗14H2O), together with mixing properties of the stilbite -stellerite solid solution (stilbite SS) are derived through assessment of geological observations of stilbite SS compositions in metabasalts, experimental phase equilibria, and calorimetric observations. Measured compositions of stilbite SS in Tertiary metabasalts in Iceland and Icelandic geothermal systems change systematically towards the stellerite endmember with increasing stratigraphic depth and temperature. Standard molal volumes, heat capacities, and entropies for the endmembers of the solid solution are derived through critical review of published crystallographic and calorimetric data for natural stilbite SS. Standard molal Gibbs energies of formation at 298.15 K and 1 bar for stilbite (-4,946,475cal mol-1) and stellerite (-4,762,036 cal mol-1) and the mixing properties of the solid solution are retrieved from observed phase- and compositional-relations in metabasalts at Berufjördur, Iceland, measured temperatures of zeolite mineral distribution in active geothermal systems, and published observations of reversed phase equilibria. Mixing in stilbite SS can be described with an athermal solid solution model. Thermodynamic data resulting from our analysis provide close correlation between compositions of stilbite SS in Icelandic geothermal systems predicted from compositions of geothermal solutions and observed compositions of these minerals in low-grade metabasalts of Iceland, as well as the observed temperature of the stilbite SS to laumontite (leonhardite) transition in Icelandic geothermal systems. Stilbite SS composition in metabasalts is a sensitive function of temperature, fluid composition, coexisting minerals (especially silica polymorphs) and geothermal gradient.

Some properties of the layer phase

International Nuclear Information System (INIS)

Fu, Y.K.; Nielsen, H.B.

1984-07-01

There exists a layer phase at least in the non-isotropic U(1) lattice gauge field model for lattice dimension D >= 5 and layer dimension d = D - 1. The authors analyze some of the main properties of the layer phase. These are as follows: the behaviour of massless gauge particles (photons); the behaviour of doubly-sign charged particles and the behaviour of Wilson loops. A non-isotropic O(N) model is suggested and analyzed too. It is proved that in this case there exists no layer phase. Finally a model involving a non-isotropic antisymmetric tensor gauge field of arbitrary order is studied and a criterion for the dimensionality of the layer phase is given. (Auth.)

Electronic properties and phase transitions in low-dimensional semiconductors

International Nuclear Information System (INIS)

Panich, A M

2008-01-01

We present the first review of the current state of the literature on electronic properties and phase transitions in TlX and TlMX 2 (M = Ga, In; X = Se, S, Te) compounds. These chalcogenides belong to a family of the low-dimensional semiconductors possessing chain or layered structure. They are of significant interest because of their highly anisotropic properties, semi- and photoconductivity, nonlinear effects in their I-V characteristics (including a region of negative differential resistance), switching and memory effects, second harmonic optical generation, relaxor behavior and potential applications for optoelectronic devices. We review the crystal structure of TlX and TlMX 2 compounds, their transport properties under ambient conditions, experimental and theoretical studies of the electronic structure, transport properties and semiconductor-metal phase transitions under high pressure, and sequences of temperature-induced structural phase transitions with intermediate incommensurate states. The electronic nature of the ferroelectric phase transitions in the above-mentioned compounds, as well as relaxor behavior, nanodomains and possible occurrence of quantum dots in doped and irradiated crystals is discussed. (topical review)

A Multistep Equilibria-Redox-Complexation Demonstration to Illustrate Le Chatelier's Principle.

Science.gov (United States)

Berger, Tomas G.; Mellon, Edward K.

1996-01-01

Describes a process that can be used to illustrate a number of chemical principles including Le Chatelier's principle, redox chemistry, equilibria versus steady state situations, and solubility of species. (JRH)

Data Requirements and Modeling for Gas Hydrate-Related Mixtures and a Comparison of Two Association Models

DEFF Research Database (Denmark)

Liang, Xiaodong; Aloupis, Georgios; Kontogeorgis, Georgios M.

2017-01-01

the performance of the CPA and sPC-SAFT EOS for modeling the fluid-phase equilibria of gas hydrate-related systems and will try to explore how the models can help in suggesting experimental measurements. These systems contain water, hydrocarbon (alkane or aromatic), and either methanol or monoethylene glycol...... parameter sets have been chosen for the sPC-SAFT EOS for a fair comparison. The comparisons are made for pure fluid properties, vapor liquid-equilibria, and liquid liquid equilibria of binary and ternary mixtures as well as vapor liquid liquid equilibria of quaternary mixtures. The results show, from...

Phase coexistence in thin liquid films stabilized by colloidal particles: equilibrium and non-equilibrium properties

International Nuclear Information System (INIS)

Blawzdziewicz, J.; Wajnryb, E.

2005-01-01

Phase equilibria between regions of different thickness in thin liquid films stabilized by colloidal particles are investigated using a quasi-two-dimensional thermodynamic formalism. Appropriate equilibrium conditions for the film tension, normal pressure, and chemical potential of the particles in the film are formulated, and it is shown that the relaxation of these parameters occurs consecutively on three distinct time scales. Film stratification is described quantitatively for a hard-sphere suspension using a Monte-Carlo method to evaluate thermodynamic equations of state. Coexisting phases are determined for systems in constrained- and full-equilibrium states that correspond to different stages of film relaxation. We also evaluated the effective viscosity coefficients for two-dimensional compressional and shear flows of a film and the self and collective mobility coefficients of the stabilizing particles. The hydrodynamic calculations were performed using a multiple-reflection representation of Stokes flow between two free surfaces. In this approach, the particle-laden film is equivalent to a periodic system of spheres with a unit cell that is much smaller in the transverse direction than in the lateral direction. (author)

Distribution equilibria of Eu(III) in the system: bis(2-ethylhexyl)phosphoric acid organic diluent-NaCl, lactic acid, polyaminocarboxylic acid, water

International Nuclear Information System (INIS)

Danesi, P.R.; Cianetti, C.; Horwitz, E.P.

1982-01-01

The distribution equilibria of Eu 3+ between aqueous phases containing lactic acid and N'-(2hydroxyethyl)ethylenediamine-N,N,N'-triacetic acid (HEDTA) or diethylenetriamine-N,N,N',N',N''-penetaacetic acid (DTPA) at constant ionic strength (μ = 1.0), and n-dodecane solutions of HDEHP have been studied. The formation constants of the simple Eu-lactate complexes and Eu-lactate-HEDTA mixed complex were evaluated from the k/sub d/ data. The conclusion is reached that no lactic acid is coextracted into the organic phase at tracer metal concentrations. The separation factors between Eu 3+ , Pm 3+ , and Am 3+ have been evaluated in the presence of HEDTA

Critical beta for analytical spheromak equilibria

International Nuclear Information System (INIS)

Freire, E.M.; Clemente, R.A.

1985-01-01

The Mercier criterion is applied to two analytical spheromak equilibria, one with a spherical separatrix and the other with a cylindrical one of variable elongation. The maximum beta, defined as the ratio between the plasma pressure and the magnetic pressure averaged over the plasma volume, for which the criterion is satisfied on every magnetic surface, has been obtained. In the spherical model the critical beta is 0.003, while in the cylindrical case it is a function of the elongation of the separatrix with a maximum of 0.083. (author)

Ballooning stable high beta tokamak equilibria

International Nuclear Information System (INIS)

Tuda, Takashi; Azumi, Masafumi; Kurita, Gen-ichi; Takizuka, Tomonori; Takeda, Tatsuoki

1981-04-01

The second stable regime of ballooning modes is numerically studied by using the two-dimensional tokamak transport code with the ballooning stability code. Using the simple FCT heating scheme, we find that the plasma can locally enter this second stable regime. And we obtained equilibria with fairly high beta (β -- 23%) stable against ballooning modes in a whole plasma region, by taking into account of finite thermal diffusion due to unstable ballooning modes. These results show that a tokamak fusion reactor can operate in a high beta state, which is economically favourable. (author)

Ultrafast characterization of phase-change material crystallization properties in the melt-quenched amorphous phase.

Science.gov (United States)

Jeyasingh, Rakesh; Fong, Scott W; Lee, Jaeho; Li, Zijian; Chang, Kuo-Wei; Mantegazza, Davide; Asheghi, Mehdi; Goodson, Kenneth E; Wong, H-S Philip

2014-06-11

Phase change materials are widely considered for application in nonvolatile memories because of their ability to achieve phase transformation in the nanosecond time scale. However, the knowledge of fast crystallization dynamics in these materials is limited because of the lack of fast and accurate temperature control methods. In this work, we have developed an experimental methodology that enables ultrafast characterization of phase-change dynamics on a more technologically relevant melt-quenched amorphous phase using practical device structures. We have extracted the crystallization growth velocity (U) in a functional capped phase change memory (PCM) device over 8 orders of magnitude (10(-10) 10(8) K/s), which reveals the extreme fragility of Ge2Sb2Te5 in its supercooled liquid phase. Furthermore, these crystallization properties were studied as a function of device programming cycles, and the results show degradation in the cell retention properties due to elemental segregation. The above experiments are enabled by the use of an on-chip fast heater and thermometer called as microthermal stage (MTS) integrated with a vertical phase change memory (PCM) cell. The temperature at the PCM layer can be controlled up to 600 K using MTS and with a thermal time constant of 800 ns, leading to heating rates ∼10(8) K/s that are close to the typical device operating conditions during PCM programming. The MTS allows us to independently control the electrical and thermal aspects of phase transformation (inseparable in a conventional PCM cell) and extract the temperature dependence of key material properties in real PCM devices.

Elastic and Mechanical Properties of the MAX Phases

Science.gov (United States)

Barsoum, Michel W.; Radovic, Miladin

2011-08-01

The more than 60 ternary carbides and nitrides, with the general formula Mn+1AXn—where n = 1, 2, or 3; M is an early transition metal; A is an A-group element (a subset of groups 13-16); and X is C and/or N—represent a new class of layered solids, where Mn+1Xn layers are interleaved with pure A-group element layers. The growing interest in the Mn+1AXn phases lies in their unusual, and sometimes unique, set of properties that can be traced back to their layered nature and the fact that basal dislocations multiply and are mobile at room temperature. Because of their chemical and structural similarities, the MAX phases and their corresponding MX phases share many physical and chemical properties. In this paper we review our current understanding of the elastic and mechanical properties of bulk MAX phases where they differ significantly from their MX counterparts. Elastically the MAX phases are in general quite stiff and elastically isotropic. The MAX phases are relatively soft (2-8 GPa), are most readily machinable, and are damage tolerant. Some of them are also lightweight and resistant to thermal shock, oxidation, fatigue, and creep. In addition, they behave as nonlinear elastic solids, dissipating 25% of the mechanical energy during compressive cycling loading of up to 1 GPa at room temperature. At higher temperatures, they undergo a brittle-to-plastic transition, and their mechanical behavior is a strong function of deformation rate.

Evaluation of the polysubstituted pyridinium ionic liquid [hmmpy][Ntf2] as a suitable solvent for desulfurization: Phase equilibria

International Nuclear Information System (INIS)

Arce, Alberto; Francisco, Maria; Soto, Ana

2010-01-01

Suitability of a pyridinium ionic liquid as a solvent in desulfurization has been analyzed. (Liquid + liquid) equilibria for ternary systems composed by 1-hexyl-3,5-dimethyl pyridinium {bis[trifluoromethylsulfonyl]imide, thiophene, and three hydrocarbons representative of fuel (n-heptane, 2,2,4 trimethylpentane, and toluene) have been determined at T = 298.15 K and atmospheric pressure. High solubility of thiophene in the ionic liquid and also of toluene have been found, being this solvent practically immiscible with 2,2,4 trimethylpentane and heptane. Equilibrium data of these systems have been well correlated with UNIQUAC equations finding the highest deviations for the ternary system involving toluene. NRTL model drove to worse results being considered as not suitable model to correlate the experimental results.

A New Approach to Modeling Densities and Equilibria of Ice and Gas Hydrate Phases

Science.gov (United States)

Zyvoloski, G.; Lucia, A.; Lewis, K. C.

2011-12-01

, and NaCl in permafrost conditions are presented to illustrate the predictive capabilities of the multi-scale GHC equation. In particular, we show that the GHC equation correctly predicts 1) The density of 1h ice and methane hydrate to within 1%. 2) The melting curve for hexagonal ice. 3) The hydrate-gas phase co-existence curve. 4) Various phase equilibrium involving ice and hydrate phases. We also show that the GHC equation approach can be readily incorporated into subsurface flow simulation programs like FEHM to predict the behavior of permafrost and other reservoirs where ice and/or hydrates are present. Many geometric illustrations are used to elucidate key concepts. References A. Lucia, A Multi-Scale Gibbs Helmholtz Constrained Cubic Equation of State. J. Thermodynamics: Special Issue on Advances in Gas Hydrate Thermodynamics and Transport Properties. Available on-line [doi:10.1155/2010/238365]. A. Lucia, B.M. Bonk, A. Roy and R.R. Waterman, A Multi-Scale Framework for Multi-Phase Equilibrium Flash. Comput. Chem. Engng. In press.

On the Size Dependence of Molar and Specific Properties of Independent Nano-phases and Those in Contact with Other Phases

Science.gov (United States)

Kaptay, George

2018-05-01

Nano-materials are materials with at least one nano-phase. A nano-phase is a phase with at least one of its dimensions below 100 nm. It is shown here that nano-phases have at least 1% of their atoms along their surface layer. The ratio of surface atoms is proportional to the specific surface area of the phase, defined as the ratio of its surface area to its volume. Each specific/molar property has its bulk value and its surface value for the given phase, being always different, as the energetic states of the atoms in the bulk and in the surface layer of a phase are different. The average specific/molar property of a nano-phase is modeled here as a linear combination of the bulk and surface values of the same property, scaled with the ratio of the surface atoms. That makes the performance of all nano-phases proportional to their specific surface area. As the characteristic size of the nano-phase is inversely proportional to its specific surface area, all specific/molar properties of nano-phases are inversely proportional to the characteristic size of the phase. This is applied to the size dependence of the molar Gibbs energy of the nano-phase, which appears to be in agreement with the thermodynamics of Gibbs. This agreement proves the general validity of the present model on the size dependence of the specific/molar properties of independent nano-phases. It is shown that the properties of nano-phases are different for independent nano-phases (surrounded only by their equilibrium vapor phase) and for nano-phases in multi-phase situations, such as a liquid nano-droplet in the sessile drop configuration.

Modeling phase equilibria for acid gas mixtures using the CPA equation of state. Part IV. Applications to mixtures of CO2 with alkanes

DEFF Research Database (Denmark)

Tsivintzelis, Ioannis; Ali, Shahid; Kontogeorgis, Georgios

2015-01-01

The thermodynamic properties of pure gaseous, liquid or supercritical CO2 and CO2 mixtures with hydrocarbons and other compounds such as water, alcohols, and glycols are very important in many processes in the oil and gas industry. Design of such processes requires use of accurate thermodynamic...... models, capable of predicting the complex phase behavior of multicomponent mixtures as well as their volumetric properties. In this direction, over the last several years, the cubic-plus-association (CPA) thermodynamic model has been successfully used for describing volumetric properties and phase...

Effects of mobile vacancies on the dynamics of ordering and phase separation in nonconserved multicomponent systems

DEFF Research Database (Denmark)

Gilhøj, Henriette; Jeppesen, Claus; Mouritsen, Ole G.

1995-01-01

The effects of mobile vacancies on the dynamics of ordering processes and phase separation in multicomponent systems are studied via Monte Carlo simulations of a two-dimensional seven-state ferromagnetic Potts model with varying degrees of site dilution. The model displays phase equilibria...

Tokamak equilibria with non-parallel flow in a triangularity-deformed axisymmetric toroidal coordinate system

Directory of Open Access Journals (Sweden)

Ap Kuiroukidis

2018-01-01

Full Text Available We consider a generalized Grad–Shafranov equation (GGSE in a triangularity-deformed axisymmetric toroidal coordinate system and solve it numerically for the generic case of ITER-like and JET-like equilibria with non-parallel flow. It turns out that increase of the triangularity improves confinement by leading to larger values of the toroidal beta and the safety factor. This result is supported by the application of a criterion for linear stability valid for equilibria with flow parallel to the magnetic field. Also, the parallel flow has a weaker stabilizing effect.

Optimization, Monotonicity and the Determination of Nash Equilibria — An Algorithmic Analysis

Science.gov (United States)

Lozovanu, D.; Pickl, S. W.; Weber, G.-W.

2004-08-01

This paper is concerned with the optimization of a nonlinear time-discrete model exploiting the special structure of the underlying cost game and the property of inverse matrices. The costs are interlinked by a system of linear inequalities. It is shown that, if the players cooperate, i.e., minimize the sum of all the costs, they achieve a Nash equilibrium. In order to determine Nash equilibria, the simplex method can be applied with respect to the dual problem. An introduction into the TEM model and its relationship to an economic Joint Implementation program is given. The equivalence problem is presented. The construction of the emission cost game and the allocation problem is explained. The assumption of inverse monotony for the matrices leads to a new result in the area of such allocation problems. A generalization of such problems is presented.

Fac–mer equilibria of coordinated iminodiacetate (ida ) in ternary Cu ...

Indian Academy of Sciences (India)

Unknown

Keywords. Fac–mer equilibria; CuII-iminodiacetate-imidazole/benzimidazole ternary complexes; stability constants. 1. Introduction. Mixed ligand complexes of transition metal ions with amino acids, peptides or their derivatives or analogues, and heterocyclic N-bases can serve as model compounds of bioinorganic interests ...

SINGLE-PHASE AND TWO-PHASE SECONDARY COOLANTS: SIMULATION AND EVALUATION OF THEIR THERMOPHYSICAL PROPERTIES

Directory of Open Access Journals (Sweden)

Pedro Samuel Gomes Medeiros

2011-09-01

Full Text Available This paper makes a comparative analysis of the thermophysical properties of ice slurry with conventional single-phase secondary fluids used in thermal storage cooling systems. The ice slurry is a two-phase fluid consisting of water, antifreeze and ice crystals. It is a new technology that has shown great energy potential. In addition to transporting energy as a heat transfer fluid, it has thermal storage properties due to the presence of ice, storing coolness by latent heat of fusion. The single-phase fluids analyzed are water-NaCl and water-propylene glycol solutions, which also operate as carrier fluids in ice slurry. The presence of ice changes the thermophysical properties of aqueous solutions and a number of these properties were determined: density, thermal conductivity and dynamic viscosity. Data were obtained by software simulation. The results show that the presence of 10% by weight of ice provides a significant increase in thermal conductivity and dynamic viscosity, without causing changes in density. The rheological behavior of ice slurries, associated with its high viscosity, requires higher pumping power; however, this was not significant because higher thermal conductivity allows a lower mass flow rate without the use of larger pumps. Thus, the ice slurry ensures its high potential as a secondary fluid in thermal storage cooling systems, proving to be more efficient than single-phase secondary fluids.

Geostrophic tripolar vortices in a two-layer fluid: Linear stability and nonlinear evolution of equilibria

Science.gov (United States)

Reinaud, J. N.; Sokolovskiy, M. A.; Carton, X.

2017-03-01

We investigate equilibrium solutions for tripolar vortices in a two-layer quasi-geostrophic flow. Two of the vortices are like-signed and lie in one layer. An opposite-signed vortex lies in the other layer. The families of equilibria can be spanned by the distance (called separation) between the two like-signed vortices. Two equilibrium configurations are possible when the opposite-signed vortex lies between the two other vortices. In the first configuration (called ordinary roundabout), the opposite signed vortex is equidistant to the two other vortices. In the second configuration (eccentric roundabouts), the distances are unequal. We determine the equilibria numerically and describe their characteristics for various internal deformation radii. The two branches of equilibria can co-exist and intersect for small deformation radii. Then, the eccentric roundabouts are stable while unstable ordinary roundabouts can be found. Indeed, ordinary roundabouts exist at smaller separations than eccentric roundabouts do, thus inducing stronger vortex interactions. However, for larger deformation radii, eccentric roundabouts can also be unstable. Then, the two branches of equilibria do not cross. The branch of eccentric roundabouts only exists for large separations. Near the end of the branch of eccentric roundabouts (at the smallest separation), one of the like-signed vortices exhibits a sharp inner corner where instabilities can be triggered. Finally, we investigate the nonlinear evolution of a few selected cases of tripoles.

Experimental study on the phase equilibria of the Ag-Ti system

International Nuclear Information System (INIS)

Fu Xiaoliang; Li Changrong; Wang Fuming; Li Mei; Zhang Weijing

2005-01-01

The Ag-Ti diffusion couples were prepared by small pure silver plates closely packed in pure titanium powder, sealed in quartz tube, and annealed at 750 deg. C, 980 deg. C, 1100 deg. C and 1200 deg. C, respectively. The phase equilibrium relationship and the conjugate phase compositions in the Ag-Ti system were determined by means of the metallographic microscope and the electron probe microanalysis. Partial liquidus and solidus for the two-phase equilibrium, liquid + (βTi), were obtained. The narrow solution range for the intermediate phase (TiAg) was determined

A Numerical Algorithm to find All Scalar Feedback Nash Equilibria

NARCIS (Netherlands)

Engwerda, J.C.

2013-01-01

Abstract: In this note we generalize a numerical algorithm presented in [9] to calculate all solutions of the scalar algebraic Riccati equations that play an important role in finding feedback Nash equilibria of the scalar N-player linear affine-quadratic differential game. The algorithm is based on

Construction of Subgame-Perfect Mixed Strategy Equilibria in Repeated Games

NARCIS (Netherlands)

Berg, Kimmo; Schoenmakers, Gijsbertus

2017-01-01

This paper examines how to construct subgame-perfect mixed-strategy equilibria in discounted repeated games with perfect monitoring.We introduce a relatively simple class of strategy profiles that are easy to compute and may give rise to a large set of equilibrium payoffs. These sets are called

P-T-x phase diagrams of MeF-UF4(Me=Li-Cs) systems

International Nuclear Information System (INIS)

Korenev, Yu.M.; Rykov, A.N.; Varkov, M.V.; Novoselova, A.V.

1988-01-01

Vapor composition and general pressure at three-phase equilibria in the MeF-UF 4 (Me=Li-Cs) systems are calculated using the values of independent component activities obtained earlier together with the data on fusibility diagrams. P-T and T-x projections of phase diagrams of these systems are constructed

A nonlocal phase-field system with inertial term

Czech Academy of Sciences Publication Activity Database

Grasselli, M.; Petzeltová, Hana; Schimperna, G.

2007-01-01

Roč. 65, č. 3 (2007), s. 451-469 ISSN 0033-569X R&D Projects: GA AV ČR(CZ) IAA100190606 Institutional research plan: CEZ:AV0Z10190503 Keywords : nonlocal phase-field system * Lojasiewicz inequality * convergence to equilibria Subject RIV: BA - General Mathematics Impact factor: 0.463, year: 2007

Thermal analysis and prediction of phase equilibria in the TiO2-Bi2O3 system

International Nuclear Information System (INIS)

Lopez-Martinez, Jaqueline; Romero-Serrano, Antonio; Hernandez-Ramirez, Aurelio; Zeifert, Beatriz; Gomez-Yanez, Carlos; Martinez-Sanchez, Roberto

2011-01-01

A thermodynamic study on the TiO 2 -Bi 2 O 3 system was carried out using differential thermal analysis (DTA) and X-Ray diffraction (XRD) techniques covering the composition range from 65 to 90 mol% Bi 2 O 3 . From the XRD results the only two intermediate compounds in the Bi 2 O 3 rich region were Bi 4 Ti 3 O 12 and Bi 12 TiO 20 . The Bi 4 Ti 3 O 12 phase presents the well known plate-like morphology. The experimentally determined phase transition temperatures with DTA technique were compared with thermodynamic calculated results and good agreement was obtained. The DTA results also showed that the limit of the peritectic reaction between liquid and Bi 4 Ti 3 O 12 occurs approximately at 90 mol% Bi 2 O 3 . The phase diagram of the TiO 2 -Bi 2 O 3 system was calculated using a quasichemical model for the liquid phase. The thermodynamic properties of the intermediate compounds were estimated from the data of TiO 2 and Bi 2 O 3 pure solids. In this manner, data for this binary system have been analysed and represented with a small adjustable parameter for the liquid phase.

Extraction equilibria of amino acids by Di (2-ethylhexyl) phosphoric acid in n-heptane solutions; Di (2-ethylhexyl) rinsan no n-heptane yoeki ni yoru aminosan no chushutsu heiko

Energy Technology Data Exchange (ETDEWEB)

Takahashi, M. [Suzuka National College of Technology, Mie (Japan); Tani, F. [Toyohashi University of Technology, Aichi (Japan); Kawai, Y. [Wako Jyunyaku Co. Ltd., Osaka (Japan); Takeuchi, H. [Nagoya University, Nagoya (Japan). Faculty of Engineering

1997-03-10

The extraction equilibria (i.e., distribution ratio) of amino acids by Di (2-ethyl hexyl) phosphoric acid in n-heptane solutions was investigated at a temperature of 298.2 K in the low pH range (of 2 to 5). The equal amount of an amino acid solution and an extracted solution with the predetermined concentration were shaken using a flask, and the concentration of amino acid in water phase was analyzed by a ninhydrin method. The concentration in organic phase was obtained by the concentration analysis in water phase and the material balance method after the amino acid is back-extracted by solution hydrochloride. The distribution ratio is in inverse proportion to the hydrogen ion concentration and in proportion to the 0.5th power of extracted agent concentration. The equilibrium constant is 0.650, 0.420, 0.320, 0.275, 0.064, and 0.040 mol{sup 0.5}/m{sup 1.5} in L-phenylalanine, L-tryptophane, L-leucine, L-methionine, glycine, and L-alanine, respectively. The equilibrium constant of the largest L-phenylalanine is 16 times as high as the smallest alanine. The extracted equilibrium constant increased as the hydrophobic property of amino acid increases. 18 refs., 10 figs., 1 tab.

Coexistence of equilibria in a New Keynesian model with heterogeneous beliefs

International Nuclear Information System (INIS)

Agliari, Anna; Pecora, Nicolò; Spelta, Alessandro

2015-01-01

The recent macroeconomic literature has been stressing the importance of considering heterogeneous expectations while addressing monetary policy. In this paper we consider a standard New Keynesian model, described by a two-dimensional nonlinear map, to analyze the bifurcation structure when agents have heterogeneous expectations and update their beliefs based on past performance. Depending on the degree of reactivity of the monetary policy to inflation and output deviations from the target equilibrium, different kind of dynamics may occur. We find that multiple equilibria and complicated dynamics, associated to codimension-2 bifurcations, may arise even if the monetary policy is set to respond more than point for point to inflation, as the Taylor principle prescribes. We show that if the monetary policy accommodates for a sufficient degree of output stabilization, complicated dynamics can be avoided and the number of coexisting equilibria reduces.

Quantum field theoretic properties of nonabelian phase factors

International Nuclear Information System (INIS)

Wieczorek, E.

1984-01-01

The paper is concerned with quantum field theoretical properies of nonabelian phase factors. The phase factors defining parallel transport in fiber bundle space are the necessary tool for the construction of gauge invariant nonlocal operators describing bound states in QCD. General structures of such operators are discussed and renormalization properties as well as relations between meson and baryon operators are obtained from a study of the underlying phase factors

Measurement of two phase flow properties using the nuclear reactor instruments

International Nuclear Information System (INIS)

Albrecht, R.W.; Washington Univ., Seattle; Crowe, R.D.; Dailey, D.J.; Kosaly, G.; Damborg, M.J.

1982-01-01

A procedure is introduced for characterizing one dimensional, two phase flow in terms of three properties; propagation, structure, and dynamics. It is shown that all of these properties can be measured by analyzing the response of the reactor neutron field to a two phase flow perturbation. Therefore, a nuclear reactor can be regarded as a two phase flow instrument. (author)

Microstructures and phase relationships in the Ti3Al + Nb system

International Nuclear Information System (INIS)

Kestner-Weykamp, H.T.; Kaufman, M.J.

1989-01-01

Alloys based on the α 2 -Ti 3 Al compound (hexagonal) DO 19 are currently experiencing limited use as advanced aerospace materials. To date, the alloys with the most desirable properties contain additions of β stabilizers, such as Nb, Mo and V, which promote the formation of a two-phase mixture of α 2 +β or α 2 +B2 (where B2 refers to the ordered CsCl structure). Unfortunately, the phase relationships in these systems have not been established in sufficient detail to allow their more widespread application. Recently, there has been a series of investigations aimed at alleviating this deficiency in the ternary Ti-Al-Nb system. These studies have clearly indicated the existence of the ordered B2 phase, which, in the higher Nb alloys, can be retained at room temperature by rapid cooling from the liquid or solid state. The authors describe (TiNb) 3 Al alloys (from 0 to 30 at. pct. Nb) were studies after conventional and nonequilibrium (i.e., rapid solidification) processing with an emphasis on providing further insight into the transformation sequences and phase equilibria in these alloys

Helical equilibria and criteria for the kink instability of cylindrical tokamak

International Nuclear Information System (INIS)

Inoue, Sanae; Itoh, Kimitaka; Yoshikawa, Shoichi.

1974-10-01

Helical equilibria and criteria for the kink instability have been obtained numerically for various current distribution, including camel hump distribution. It is found that the unstable region expressed by q(a) is the largest in the case of uniform current. (auth.)

Magnetic coordinates for equilibria with a continuous symmetry

International Nuclear Information System (INIS)

Dewar, R.L.; Monticello, D.A.; Sy, W.N.C.

1983-08-01

Magnetic coordinates for hydromagnetic equilibria are defined which treat toroidal and straight helical plasmas equivalently yet exploit the existence of a continuous symmetry to derive relations between various geometrical and physical quantities. This allows the number of equilibrium quantities which must be known to be reduced to a minimal, or primitive set. Practical formulae for various quantities required in hydromagnetic stability calculations (interchange, ballooning, and global) are given in terms of this primitive set

Properties and Applications of the β Phase Poly(vinylidene fluoride

Directory of Open Access Journals (Sweden)

Liuxia Ruan

2018-02-01

Full Text Available Poly(vinylidene fluoride, PVDF, as one of important polymeric materials with extensively scientific interests and technological applications, shows five crystalline polymorphs with α, β, γ, δ and ε phases obtained by different processing methods. Among them, β phase PVDF presents outstanding electrical characteristics including piezo-, pyro-and ferroelectric properties. These electroactive properties are increasingly important in applications such as energy storage, spin valve devices, biomedicine, sensors and smart scaffolds. This article discusses the basic knowledge and character methods for PVDF fabrication and provides an overview of recent advances on the phase modification and recent applications of the β phase PVDF are reported. This study may provide an insight for the development and utilization for β phase PVDF nanofilms in future electronics.

Study of SmS properties in the low pressure phase (black phase)

International Nuclear Information System (INIS)

Bordier, G.

1986-01-01

SmS was studied for the transition from low pressure phase (black phase) to high pressure phase with an intermediate valence. But the study of the black phase is very rich. The variations of electron transport properties with pressure at low temperature show a semi-metal phase located, in the pressure-temperature diagram in the black phase for pressure over 4 kbars, corresponding to the phase B'of the doping-temperature diagram. Electron spin resonance shows a lack of sulfur and nearby this defect a samarium ion, magnetically coupled with the matrix, presents a divalent trivalent transition. Resonance lines are broadened with temperature. Conductivity relaxations occur at low pressure and low temperature by trapping a conduction electron, by magnetic exchange giving a bounded magnetic polaron. The relaxation time at null magnetic field is activated. An approximation of trapping barrier and critical field corresponding the maximum magnetoresistance is given by a model [fr

A note on relative equilibria in a rotating shallow water layer

KAUST Repository

Ait Abderrahmane, Hamid; Fayed, Mohamed; Ng, Hoidick; Vatistas, Georgios H.

2013-01-01

the fundamental characteristics of Kelvin's equilibria, and could be adequately described by the classical idealized point vortex theory. The same conclusion can also be inferred using the experimental dataset of Bergmann et al. (J. Fluid Mech., vol. 679, 2011

Equilibria of the three-body problem with rigid dumb-bell satellite

International Nuclear Information System (INIS)

Elipe, A.; Palacios, M.; Pretka-Ziomek, H.

2008-01-01

This paper is concerned with the orbital-rotational motion of an asymmetric dumb-bell (two masses with fixed distance among them) under the attraction of a central body. For this model, we find some equilibria and give sufficient conditions for their stability

Modeling phase equilibria of alkanols with the simplified PC-SAFT equation of state and generalized pure compound parameters

DEFF Research Database (Denmark)

Grenner, Andreas; Kontogeorgis, Georgios; von Solms, Nicolas

2007-01-01

The simplified PC-SAFT equation of state has been applied to liquid-liquid, vapor-liquid and solid-liquid equilibria for mixtures containing 1-or 2-alkanols with alkanes, aromatic hydrocarbons, CO2 and water. For the alkanols we use generalized pure compound parameters. This means that two...... of the physical pure compound parameters, in (segment number) and or (segment diameter), are obtained from linear extrapolations, since m and m sigma(3), increase linearly with respect to the molar mass, and moreover, the two association parameters (association energy and association volume) were assumed...... to be constant for all alkanols. Only the dispersion energy is fitted to experimental data. Thus it is possible to estimate parameters for several 1-and 2-alkanols. The final aim is to develop a group contribution approach for PC-SAFT which is suitable for complex compounds, considering that the motivation...

Guiding Center Equations in Toroidal Equilibria

International Nuclear Information System (INIS)

White, Roscoe; Zakharov, Leonid

2002-01-01

Guiding center equations for particle motion in a general toroidal magnetic equilibrium configuration are derived using magnetic coordinates. Previous derivations made use of Boozer coordinates, in which the poloidal and toroidal angle variables are chosen so that the Jacobian is inversely proportional to the square of the magnetic field. It is shown that the equations for guiding center motion in any equilibrium possessing nested flux surfaces have exactly the same simple form as those derived in this special case. This allows the use of more spatially uniform coordinates instead of the Boozer coordinates, greatly increasing the accuracy of calculations in large beta and strongly shaped equilibria

The free energy of Maxwell-Vlasov equilibria

International Nuclear Information System (INIS)

Morrison, P.J.; Pfirsch, D.

1989-10-01

A previously derived expression for the energy of arbitrary perturbations about arbitrary Vlasov-Maxwell equilibria is transformed into a very compact form. The new form is also obtained by a canonical transformation method for solving Vlasov's equation, which is based on Lie group theory. This method is simpler than the one used before and provides better physical insight. Finally a procedure is presented for determining the existence of negative-energy modes. In this context the question of why there is an accessibility constraint for the particles, but not for the fields, is discussed. 16 refs

Modelling (vapour + liquid) and (vapour + liquid + liquid) equilibria of {water (H2O) + methanol (MeOH) + dimethyl ether (DME) + carbon dioxide (CO2)} quaternary system using the Peng-Robinson EoS with Wong-Sandler mixing rule

International Nuclear Information System (INIS)

Ye Kongmeng; Freund, Hannsjoerg; Sundmacher, Kai

2011-01-01

Highlights: → Phase behaviour modelling of H 2 O-MeOH-DME under pressurized CO 2 (anti-solvent) using PRWS. → PRWS-UNIFAC-PSRK has better performance than PRWS-UNIFAC-Lby in general. → Reliable to extend the VLE and VLLE phase behaviour from binary to multicomponent systems. → Successful prediction of the VLE and VLLE of binary, ternary, and quaternary systems. → Potential to apply the model for designing new DME separation process. - Abstract: The (vapour + liquid) equilibria (VLE) and (vapour + liquid + liquid) equilibria (VLLE) binary data from literature were correlated using the Peng-Robinson (PR) equation of state (EoS) with the Wong-Sandler mixing rule (WS). Two group contribution activity models were used in the PRWS: UNIFAC-PSRK and UNIFAC-Lby. The systems were successfully extrapolated from the binary systems to ternary and quaternary systems. Results indicate that the PRWS-UNIFAC-PSRK generally displays a better performance than the PRWS-UNIFAC-Lby.

Method for estimating critical properties of heavy compounds suitable for cubic equations of state and its application to the prediction of vapor pressures

DEFF Research Database (Denmark)

Kontogeorgis, Georgios; Ioannis, Smirlis; Iakovos, Yakoumis

1997-01-01

S. The proposed scheme employs a recent group-contribution method (Constantinou et al. Fluid Phase Equilib. 1995, 103 (1), 11) for estimating the acentric factor. The two critical properties are estimated via a generalized correlation for the ratio T-c/P-c (with the van der Waals surface area) and the cubic Eo...... pressures for several nonpolar and slightly polar heavy compounds with very satisfactory results, essentially independent of the experimental point used. Furthermore, the method yields critical properties for heavy alkanes (N-c > 20) and other compounds which are in very good agreement with recent available......Cubic equations of state (EoS) are often used for correlating and predicting phase equilibria. Before extending any EoS to mixtures, reliable vapor-pressure prediction is essential. This requires experimental, if possible, critical temperatures T-c, pressures P-c, and acentric factor omega...

Deep Recycling of Sedimentary Lithologies in Subduction Zones: Geochemical and Physical Constraints from Phase Equilibria and Synchrotron-Based Multi-Anvil Experiments at 15-25 GPa

Science.gov (United States)

Rapp, R. P.; Nishiyama, N.; Irifune, T.; Inoue, T.; Yamasaki, D.

2003-12-01

Ocean island basalts (OIBs) provide geochemical evidence for the presence of crustally-derived sedimentary material in the deep mantle plume source region for EM-type OIBs, and global seismic tomography provides us with dramatic images of subducted slabs, presumably carrying a sediment component, penetrating through the transition zone and into the lower mantle, in some cases to the core-mantle boundary. In an effort to better constrain the geochemical effects of deeply recycled sedimentary material in subduction zones, and their role in the petrogenesis of EM-type OIBs, we have undertaken a series of phase equlibria experiments in the multi-anvil apparatus at 10-25 GPa, using natural sediment lithologies as starting materials. The goal of these experiments is to identify the dominant phases in deeply subducted sediments, constrain their P-T stability limits, and to assess their role in crustal recycling and element redistribution in the deep mantle during subduction. The phase equilibria experiments were performed in a 2000-ton Kawai-type apparatus, using tungsten carbide cubes with 3 mm TEL and Cr-doped MgO and zirconia pressure media. A cylindrical lanthanum chromite heater was used, along with short (gold capsules to minimize thermal gradients and to retain the small amounts of water (< 1 wt%) present in the starting material, and long run-durations (12-48 hours) in order to facilitate future analyses of the dominant phases for key trace elements using the ion microprobe. Our preliminary results at 10-25 GPa indicate that K-hollandite (KalSi3O3) and stishovite are the primary high-pressure phases in the sediment composition, with subordinate garnet and an as-yet-unidentified (possibly hydrous) Al-silicate phase present as well. These results suggest that K-hollandite is the primary repository for incompatible elements (e.g., La, Ce, Sr, Ba, Rb, etc., and the heat-producing elements K, U and Th) in sedimentary material recycled into the deep mantle via

Review of Liquidus Surface and Phase Equilibria in the TiO2-SiO2-Al2O3-MgO-CaO Slag System at PO2 Applicable in Fluxed Titaniferous Magnetite Smelting

Science.gov (United States)

Goso, Xolisa; Nell, Johannes; Petersen, Jochen

The current liquidus surface and phase equilibria established in air for fluxed titaniferous magnetite (titanomagnetite) slags conforming to a composition of 37.19% TiO2, 19.69% SiO2, 13.12% Al2O3, and 30.00% of various ratios of CaO+MgO were reviewed at applicable PO2 using FactSage simulation and phase composition of a real plant titanomagnetite slag. The testwork included the incorporation into FactSage of a private MgTi2O5-Al2TiO5 pseudobrookite solution model. The results of the investigation showed that the liquidus surface and Ti3+/ Ti4+ mass fraction ratio increased with decreasing the PO2, At low PO2, perovskite crystallizes as a primary phase at high CaO content. The spinel solution, i.e. (Mg)(Al,Ti)O4, generally crystallizes as the primary phase at high MgO contents, though it is replaced by MgTi2O5-Al2TiO5 solution at PO2 of 10-10 atm to 10-15 atm. An intermediate equilibrium phase diagram established at PO2 of 10-16 atm is proposed. This phase diagram does not show the observed primary phase crystallization competition, however, the phase composition of a real titanomagnetite slag produced by Evraz Highveld Steel and Vanadium Corporation in South Africa does show primary phase crystallization competition between (Mg)(Al,Ti)2O4 and MgTi2O5-Al2TiO5. Smelting involving such slags is likely conducted around the transition PO2, i.e. PO2 of about 10-16 atm. Complex modelling with MgTi2O5, Al2TiO5 and Ti3O5 end members and experiments are underway to verify and update the intermediate phase diagram.

Phase transitions in solids under high pressure

CERN Document Server

Blank, Vladimir Davydovich

2013-01-01

Phase equilibria and kinetics of phase transformations under high pressureEquipment and methods for the study of phase transformations in solids at high pressuresPhase transformations of carbon and boron nitride at high pressure and deformation under pressurePhase transitions in Si and Ge at high pressure and deformation under pressurePolymorphic α-ω transformation in titanium, zirconium and zirconium-titanium alloys Phase transformations in iron and its alloys at high pressure Phase transformations in gallium and ceriumOn the possible polymorphic transformations in transition metals under pressurePressure-induced polymorphic transformations in АIBVII compoundsPhase transformations in AIIBVI and AIIIBV semiconductor compoundsEffect of pressure on the kinetics of phase transformations in iron alloysTransformations during deformation at high pressure Effects due to phase transformations at high pressureKinetics and hysteresis in high-temperature polymorphic transformations under pressureHysteresis and kineti...

Exotic equilibria of Harary graphs and a new minimum degree lower bound for synchronization

KAUST Repository

Canale, Eduardo A.

2015-02-01

© 2015 AIP Publishing LLC. This work is concerned with stability of equilibria in the homogeneous (equal frequencies) Kuramoto model of weakly coupled oscillators. In 2012 [R. Taylor, J. Phys. A: Math. Theor. 45, 1-15 (2012)], a sufficient condition for almost global synchronization was found in terms of the minimum degree-order ratio of the graph. In this work, a new lower bound for this ratio is given. The improvement is achieved by a concrete infinite sequence of regular graphs. Besides, non standard unstable equilibria of the graphs studied in Wiley et al. [Chaos 16, 015103 (2006)] are shown to exist as conjectured in that work.

Theory of Perturbed Equilibria for Solving the Grad-Shafranov Equation

International Nuclear Information System (INIS)

Pletzer, A.; Zakharov, L.E.

1999-01-01

The theory of perturbed magnetohydrodynamic equilibria is presented for different formulations of the tokamak equilibrium problem. For numerical codes, it gives an explicit Newton scheme for solving the Grad-Shafranov equation subject to different constraints. The problem of stability of axisymmetric modes is shown to be a particular case of the equilibrium perturbation theory

Surface currents on the plasma-vacuum interface in MHD equilibria

Science.gov (United States)

Hanson, James

2017-10-01

The VMEC non-axisymmetric MHD equilibrium code can compute free-boundary equilibria. Since VMEC assumes that magnetic fields within the plasma form closed and nested flux surfaces, the plasma-vacuum interface is a flux surface, and the total magnetic field there has no normal component. VMEC imposes this condition of zero normal field using the potential formulation of Merkel, and solves a Neumann problem for the magnetic potential in the exterior region. This boundary condition necessarily admits the possibility of a surface current on the interface. While this surface current may be small in MHD equilibrium, it is readily computed in terms of the magnetic potentials in both the interior and exterior regions, evaluated on the surface. If only the external magnetic potential is known (as in VMEC), then the surface current can be computed from the discontinuity of the tangential field across the interface. Examples of the surface current for VMEC equilibria will be shown for a zero-pressure stellarator equilibrium. Field-line following of the vacuum magnetic field shows magnetic islands within the plasma region.

Ab initio study of phase equilibria in TiCx

DEFF Research Database (Denmark)

Korzhavyi, P.A.; Pourovskii, L.V.; Hugosson, H.W.

2002-01-01

The phase diagram for the vacancy-ordered structures in the substoichiometric TiCx (x = 0.5-1.0) has been established from Monte Carlo simulations with the long-range pair and multisite effective interactions obtained from ab initio calculations. Three ordered superstructures of vacancies (Ti2C, Ti...

A Scanning Hologram Recorded by Phase Conjugate Property of Nonlinear Crystals

DEFF Research Database (Denmark)

Zi-Liang, Ping; Dalsgaard, Erik

1996-01-01

A methode of recording a scanning hologram with phase conjugate property of nonlinear crystal is provided. The principle of recording, setup and experiments are given.......A methode of recording a scanning hologram with phase conjugate property of nonlinear crystal is provided. The principle of recording, setup and experiments are given....

Use of isoconcentrational phase diagrams for prediction of amorphization of binary systems

International Nuclear Information System (INIS)

Lazarev, A.I.; Belashchenko, D.K.

1992-01-01

Based on the application of isoconcentrational diagrams of phase equilibria of liquid with solid solutions of various crystal structures the thermodynamic method was considered for prediction of concentration ranges of amorphization in binary systems.To confirm the applicability of the thermodynamic criterion in practice caclulations of phase diagrams were accomplished for complex binary eutectic systems (Hf-Be, Zr-Be) with the known concentration ranges of amorphization

Simulating Osmotic Equilibria: A New Tool for Calculating Activity Coefficients in Concentrated Aqueous Salt Solutions.

Science.gov (United States)

Bley, Michael; Duvail, Magali; Guilbaud, Philippe; Dufrêche, Jean-François

2017-10-19

Herein, a new theoretical method is presented for predicting osmotic equilibria and activities, where a bulk liquid and its corresponding vapor phase are simulated by means of molecular dynamics using explicit polarization. Calculated time-averaged number density profiles provide the amount of evaporated molecules present in the vapor phase and consequently the vapor-phase density. The activity of the solvent and the corresponding osmotic coefficient are determined by the vapor density at different solute concentrations with respect to the reference vapor density of the pure solvent. With the extended Debye-Hückel equation for the activity coefficient along with the corresponding Gibbs-Duhem relation, the activity coefficients of the solutes are calculated by fitting the osmotic coefficients. A simple model based on the combination of Poisson processes and Maxwell-Boltzmann velocity distributions is introduced to interpret statistical phenomena observed during the simulations, which are related to evaporation and recondensation. This method is applied to aqueous dysprosium nitrate [Dy(NO 3 ) 3 ] solutions at different concentrations. The obtained densities of the liquid bulk and the osmotic and activity coefficients are in good agreement with the experimental results for concentrated and saturated solutions. Density profiles of the liquid-vapor interface at different concentrations provide detailed insight into the spatial distributions of all compounds.

A note on the energy of relative equilibria of point vortices

DEFF Research Database (Denmark)

Aref, Hassan

2007-01-01

Analytical formulas are derived for the energy of simple relative equilibria of identical point vortices such as the regular polygons, both open and centered, and the various known configurations consisting of nested regular polygons with or without a vortex at the center. ©2007 American Institute...

Prediction of the vapor–liquid equilibria and speed of sound in binary systems of 1-alkanols and n-alkanes with the simplified PC-SAFT equation of state

DEFF Research Database (Denmark)

Liang, Xiaodong; Thomsen, Kaj; Yan, Wei

2013-01-01

(or other derivative properties) with satisfactory accuracy over wide temperature, pressure and composition conditions. This work presents the prediction of the vapor–liquid equilibria and speed of sound in binary mixtures of 1-alkanols and n-alkanes using the simplified PC-SAFT equation of state...... of sound with a satisfactory accuracy for 1-alkanols and n-alkanes binary systems within the PC-SAFT framework....

Chimera States in Two Populations with Heterogeneous Phase-lag

DEFF Research Database (Denmark)

Martens, Erik Andreas; Bick, Christian; Panaggio, Mark

2016-01-01

The simplest network of coupled phase-oscillators exhibiting chimera states is given by two populations with disparate intra- and inter-population coupling strengths. We explore the effects of heterogeneous coupling phase-lags between the two populations. Such heterogeneity arises naturally......-uniform synchronization, including in-phase and anti-phase synchrony, full incoherence (splay state), chimera states with phase separation of 0 or π between populations, and states where both populations remain desynchronized. These desynchronized states exhibit stable, oscillatory, and even chaotic dynamics. Moreover......, we identify the bifurcations through which chimera and desynchronized states emerge. Stable chimera states and desynchronized solutions, which do not arise for homogeneous phase-lag parameters, emerge as a result of competition between synchronized in-phase, anti-phase equilibria, and fully...

Phase Transformations in Cast Duplex Stainless Steels

Energy Technology Data Exchange (ETDEWEB)

Kim, Yoon-Jun [Iowa State Univ., Ames, IA (United States)

2004-01-01

Duplex stainless steels (DSS) constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as σ and χ can also form during casting or high-temperature processing and can degrade the properties of the DSS. This research was initiated to develop time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams of two types of cast duplex stainless steels, CD3MN (Fe-22Cr-5Ni-Mo-N) and CD3MWCuN (Fe-25Cr-7Ni-Mo-W-Cu-N), in order to understand the time and temperature ranges for intermetallic phase formation. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy (SEM, TEM) and wavelength dispersive spectroscopy (WDS). The kinetics of intermetallic-phase (σ + χ) formation were analyzed using the Johnson-Mehl-Avrami (MA) equation in the case of isothermal transformations and a modified form of this equation in the case of continuous cooling transformations. The rate of intermetallic-phase formation was found to be much faster in CD3MWCuN than CD3MN due mainly to differences in the major alloying contents such as Cr, Ni and Mo. To examine in more detail the effects of these elements of the phase stabilities; a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc. In general, σ was stabilized with increasing Cr addition and χ by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in DSS can be affected by

Powder processing of high Tc oxide superconductors and their properties

International Nuclear Information System (INIS)

Vajpei, A.C.; Upadhyaya, G.S.

1992-01-01

Powder processing of ceramics is an established technology and in the area of high T c superconductors, its importance is felt even more significantly. The present monograph is an attempt in this direction to explore the perspectives and practice of powder processing routes towards control and optimization of the microstructure and pertinent properties of high T c oxide superconductors. The monograph consists of 6 chapters. After a very brief introduction (Chapter 1), Chapter 2 describes various classes of high T c oxide superconductors and their phase equilibria. Chapter 3 highlights the preparation of oxide superconductor powders through various routes and details their subtle distinctions. Chapter 4 briefly covers characterisation of the oxide superconductors, laying emphasis on the process-analysis and microstructure. Chapter 5 describes in detail various fabrication techniques for bulk superconductors through the powder routes. The last Chapter (Chapter 6) describing properties of bulk oxide superconductors, discusses the role of subtituents, compositional variations and processing methods on such properties. References are given at the end of each chapter. (orig.)

Influence of somatic cell count on mineral content and salt equilibria of milk

Directory of Open Access Journals (Sweden)

Primo Mariani

2010-01-01

Full Text Available Aim of this research was to study the effect of somatic cell count on mineral content and salt equilibria at the level of quarter milk samples. Ten Italian Friesian cows, in which two homologous quarters (front quarters in 1 cow, rear quarters in 6 cows and both rear and front quarters in 3 cows were characterised by a milk SCC400,000 cells/mL (HC-milk, respectively, were selected. Cows were milked at quarter level during the morning milking and a single sample was collected from each selected quarter, thus, 26 quarter milk samples were collected. Compared to LC-milk, HC-milk was characterised by a lower content of phosphorus and potassium and by a higher content of both sodium and chloride. The equilibrium of calcium, phosphorus and magnesium between the colloidal and soluble phase of milk and the mineralisation degree of the casein micelles, were not different between HC and LC milk.

Experimental investigation and thermodynamic calculations of the Bi–In–Ni phase diagram

International Nuclear Information System (INIS)

Premović, Milena; Minić, Duško; Manasijević, Dragan; Ćosović, Vladan; Živković, Dragana; Dervišević, Irma

2015-01-01

Highlights: • Calculated constitutive binary system based on literature data. • Experimentally determined (DTA) temperatures of phase transformations compared with analytical calculation. • Definition of several vertical sections. • Calculated horizontal section, confirmed by experimental SEM–EDS and XRD method. • Calculated liquidus surface projection and determined invariant reaction occurred in ternary Bi–In–Ni system. - Abstract: Phase diagram of the Bi–In–Ni ternary system was investigated using differential thermal analysis (DTA), scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), and X-ray powder diffraction (XRD) analysis. Experimentally obtained results were compared with the results of thermodynamic calculation of phase equilibria based on calculation of phase diagram (CALPHAD) method and literature data. Phase transition temperatures of alloys with overall compositions along three selected vertical sections In–Bi 0.8 Ni 0.2 , x(Bi) = 0.6 and Bi–In 0.5 Ni 0.5 were measured by DTA. Liquidus temperatures were experimentally determined and compared with the results of thermodynamic calculation. Identification of coexisting phases in samples equilibrated at 100 °C, 300 °C and 350 °C was carried out using SEM–EDS and XRD methods. The obtained results were compared with the calculated isothermal sections of the Bi–In–Ni ternary system at corresponding temperatures. Calculated liquidus projection and invariant equilibria of the Bi–In–Ni ternary system were presented

Enthalpy of phase transition and prediction of phase Equilibria in systems of glycols and glycol ethers

OpenAIRE

Esina, Zoya; Miroshnikov, Aleksandr; Korchuganova, Margarita

2014-01-01

The PCEAS model was used to study the liquid-solid and liquid-vapor phase transitions at constant pressure in systems containing glycols and glycol ethers. This method is based on minimizing the excess Gibbs energy over the solvation parameter, which takes into account the processes of association of molecules in various phases. To compute the diagrams, the data on enthalpy and phase transition temperatures of pure components are required, while the information about the interactions in the b...

Characterization of thermal and hydrodynamic properties for microencapsulated phase change slurry (MPCS)

International Nuclear Information System (INIS)

Chen, Lin; Wang, Ting; Zhao, Yan; Zhang, Xin-Rong

2014-01-01

Highlights: • Microencapsulated phase change slurry (MPCS) is reviewed and characterized for heat transfer and storage systems. • Basic formation, materials, properties are categorized and systematically analyzed. • Generalization and modelization of complex MPCS properties are made. • MPCS is identified to be one promising substitute in future energy systems. • Future research topics and applications are also specified. - Abstract: Microencapsulated phase change slurry (MPCS) is a new kind of multi-phase fluid that are proposed and utilized in heat transfer and heat storage systems. Different from traditional organic (paraffin or non-parafin) or inorganic phase change slurries, MPCS is able to maintain both high latent heat capacity and heat transfer rate under controlled volume changes and safe operation conditions. Consequently, in recent decade, MPCS has been widely proposed and tested in textile, building, cooling and heating, solar and thermal storage systems, etc. Based on those recent findings and application developments, characterizations of thermal and hydrodynamic properties for MPCS are made in this study. The basic objective of this paper is to summarize the features of MPCS properties and the establishment of models for MPCS properties and morphologies. The review and analysis are based on recent representative experimental studies, which are categorized into: properties, heat transfer characteristics, stability and applications. Due to the various materials and methods and carry fluids properties, no single model can cover the properties for all MPCS. In this study, each property is reviewed with its specific model and application regions. Basic trends are compared with other kinds of phase change materials. Finally, by investigating those results the future trends of MPCS are presented

Thermodynamic modelling of phase equilibrium for water + poly(Ethylene glycol + salt aqueous two-phase systems

Directory of Open Access Journals (Sweden)

R.A.G. Sé

2002-04-01

Full Text Available The NRTL (nonrandom, two-liquid model, expressed in mass fraction instead of mole fraction, was used to correlate liquid-liquid equilibria for aqueous two-phase polymer-salt solutions. New interaction energy parameters for this model were determined using reported data on the water + poly(ethylene glycol + salt systems, with different molecular masses for PEG and the salts potassium phosphate, sodium sulfate, sodium carbonate and magnesium sulfate. The correlation of liquid-liquid equilibrium is quite satisfactory.

Properties of high-density matter in the electroweak symmetric phase

International Nuclear Information System (INIS)

Chandra, D.; Goyal, A.

1992-01-01

We examine the bulk properties of matter at high densities and finite temperatures in the phase where electroweak symmetry is exact and fermions are massless, by taking the strong interactions into account perturbatively to lowest order in the quark-gluon chromodynamic coupling constant α c . We also discuss the possibility of a phase transition of strange quark matter into this high-density matter in the electroweak symmetric phase at densities likely to be present in the core of dense neutron stars or collapsing stars. Finally, we study the properties of finite-size chunks of this matter by taking surface effects into account and give an estimate of the surface tension

A Computer Algebra Approach to Solving Chemical Equilibria in General Chemistry

Science.gov (United States)

Kalainoff, Melinda; Lachance, Russ; Riegner, Dawn; Biaglow, Andrew

2012-01-01

In this article, we report on a semester-long study of the incorporation into our general chemistry course, of advanced algebraic and computer algebra techniques for solving chemical equilibrium problems. The method presented here is an alternative to the commonly used concentration table method for describing chemical equilibria in general…

Modeling strontium-cesium-calcium-magnesium-sodium ion exchange equilibria on chabazite with the Wilson equation

International Nuclear Information System (INIS)

Perona, J.J.

1992-01-01

Chabazite zeolites are used at ORNL for decontamination of wastewaters containing 90 Sr and 137 Cs. Treatability studies have shown that chabazite can remove trace amounts of these nuclides from wastewaters containing much higher concentrations of calcium and magnesium. The design of ion exchange columns for multicomponent systems requires a method for predicting multicomponent equilibria from binary or ternary experiments, since the number of experiments required for an empirical equilibrium model is generally not feasible. Binary interaction parameters for the Wilson equation were used to predict solid-phase activity coefficients for the five-component system, and the sum of squares of deviations between experimental and predicted solution concentrations for the data points available was calculated. The average deviation per data point for the five-component system was about the same as for the calcium-magnesium-sodium ternary system

Control Algorithms Along Relative Equilibria of Underactuated Lagrangian Systems on Lie Groups

DEFF Research Database (Denmark)

Nordkvist, Nikolaj; Bullo, F.

2008-01-01

We present novel algorithms to control underactuated mechanical systems. For a class of invariant systems on Lie groups, we design iterative small-amplitude control forces to accelerate along, decelerate along, and stabilize relative equilibria. The technical approach is based upon a perturbation...

Control algorithms along relative equilibria of underactuated Lagrangian systems on Lie groups

DEFF Research Database (Denmark)

Nordkvist, Nikolaj; Bullo, Francesco

2007-01-01

We present novel algorithms to control underactuated mechanical systems. For a class of invariant systems on Lie groups, we design iterative small-amplitude control forces to accelerate along, decelerate along, and stabilize relative equilibria. The technical approach is based upon a perturbation...

Phase-field modelling of microstructural evolution and properties

Science.gov (United States)

Zhu, Jingzhi

As one of the most powerful techniques in computational materials science, the diffuse-interface phase-field model has been widely employed for simulating various meso-scale microstructural evolution processes. The main purpose of this thesis is to develop a quantitative phase-field model for predicting microstructures and properties in real alloy systems which can be linked to existing thermodynamic/kinetic databases and parameters obtained from experimental measurements or first-principle calculations. To achieve this goal; many factors involved in complicated real systems are investigated, many of which are often simplified or ignored in existing models, e.g. the dependence of diffusional atomic mobility and elastic constants on composition. Efficient numerical techniques must be developed to solve those partial differential equations that are involved in modelling microstructural evolutions and properties. In this thesis, different spectral methods were proposed for the time-dependent phase-field kinetic equations and diffusion equations. For solving the elastic equilibrium equation with the consideration of elastic inhomogeneity, a conjugate gradient method was utilized. The numerical approaches developed were generally found to be more accurate and efficient than conventional approach such as finite difference method. A composition-dependent Cahn-Hilliard equation was solved by using a semi-implicit Fourier-spectral method. It was shown that the morphological evolutions in bulk-diffusion-controlled coarsening and interface-diffusion-controlled developed similar patterns and scaling behaviors. For bulk-diffusion-controlled coarsening, a cubic growth law was obeyed in the scaling regime, whereas a fourth power growth law was observed for interface-diffusion-controlled coarsening. The characteristics of a microstructure under the influence of elastic energy depend on elastic properties such as elastic anisotropy, lattice mismatch, elastic inhomogeneity and

Investigation of B2 and related phases in the Ti-Al-Nb ternary systems

International Nuclear Information System (INIS)

Bendersky, L.A.; Boettinger, W.J.

1989-01-01

Alloy compositions around Ti 2 AlNb were studied to establish phase equilibria and transformations during cooling from 1100 degrees C and 1400 degrees C. In addition to general results obtained on a wide range of compositions, which include evidence for a broad B2 phase field, transformation of BCC Ti 4 Al 3 Nb to a phase with an omega-type structure is reported. Detailed analysis indicates that this phase has the B8 2 structure after annealing at 700 degrees C

Path integrals over phase space, their definition and simple properties

International Nuclear Information System (INIS)

Tarski, J.; Technische Univ. Clausthal, Clausthal-Zellerfeld

1981-10-01

Path integrals over phase space are defined in two ways. Some properties of these integrals are established. These properties concern the technique of integration and the quantization rule isup(-I)deltasub(q) p. (author)

Study of the low pressure (Black Phase) SmS properties

International Nuclear Information System (INIS)

Bordier, G.

1987-03-01

SmS has been studied for its transition from the low pressure black phase to the high pressure intermediate valence phase; but the black phase properties seem to be very rich. The variations which pressure of the low-temperature electronic transport properties show the existence of a semi-metallic phase within the black phase domain in a pressure-temperature diagram, for a pressure above 4 kbar, which corresponds to the so-called B'phase. We study the insulating low pressure phase with a model involving acceptor like states. Using electronic paramagnetic resonance experiments we observe a square symmetry trivalent samarium ion neighbour of a sulfure defect, and magnetically coupled with the lattice. This defect exists in two nearly symmetric configurations and the resonance line broadens with temperature in an actived way. It gives rise to metastable effects yielding conductivity relaxations, analysed with stretched exponential laws, because the defect traps magnetically conduction electrons forming a bound magnetic polaron. The relaxation time at zero field is temperature actived. We develop a phenomenological model that gives the good orders of magnitude for the trapping barrier and for the critical field corresponding to the maximum of the low temperature magnetoresistance [fr

Stable equilibria for bootstrap-current-driven low aspect ratio tokamaks

International Nuclear Information System (INIS)

Miller, R.L.; Lin-Liu, Y.R.; Turnbull, A.D.; Chan, V.S.; Pearlstein, L.D.; Sauter, O.; Villard, L.

1997-01-01

Low aspect ratio tokamaks (LATs) can potentially provide a high ratio of plasma pressure to magnetic pressure β and high plasma current I at a modest size. This opens up the possibility of a high-power density compact fusion power plant. For the concept to be economically feasible, bootstrap current must be a major component of the plasma current, which requires operating at high β p . A high value of the Troyon factor β N and strong shaping is required to allow simultaneous operation at a high-β and high bootstrap fraction. Ideal magnetohydrodynamic stability of a range of equilibria at aspect ratio 1.4 is systematically explored by varying the pressure profile and shape. The pressure and current profiles are constrained in such a way as to assure complete bootstrap current alignment. Both β N and β are defined in terms of the vacuum toroidal field. Equilibria with β N ≥8 and β∼35%endash 55% exist that are stable to n=∞ ballooning modes. The highest β case is shown to be stable to n=0,1,2,3 kink modes with a conducting wall. copyright 1997 American Institute of Physics

Benzimidazole acrylonitriles as multifunctional push-pull chromophores: Spectral characterisation, protonation equilibria and nanoaggregation in aqueous solutions

Science.gov (United States)

Horak, Ema; Vianello, Robert; Hranjec, Marijana; Krištafor, Svjetlana; Zamola, Grace Karminski; Steinberg, Ivana Murković

2017-05-01

Heterocyclic donor-π-acceptor molecular systems based on an N,N-dimethylamino phenylacrylonitrile benzimidazole skeleton have been characterised and are proposed for potential use in sensing applications. The benzimidazole moiety introduces a broad spectrum of useful multifunctional properties to the system including electron accepting ability, pH sensitivity and compatibility with biomolecules. The photophysical characterisation of the prototropic forms of these chromophores has been carried out in both solution and on immobilisation in polymer films. The experimental results are further supported by computational determination of pKa values. It is noticed that compound 3 forms nanoaggregates in aqueous solutions with aggregation-induced emission (AIE) at 600 nm. All the systems demonstrate spectral pH sensitivity in acidic media which shifts towards near-neutral values upon immobilisation in polymer films or upon aggregation in an aqueous environment (compound 3). The structure-property relationships of these functional chromophores, involving their spectral characteristics, acid-base equilibria, pKa values and aggregation effects have been determined. Potential applications of the molecules as pH and biomolecular sensors are proposed based on their pH sensitivity and AIE properties.

(Liquid + liquid) equilibria of binary systems containing hyperbranched polymer Boltorn (registered) H2004 - Experimental study and modelling in terms of lattice-cluster theory

International Nuclear Information System (INIS)

Domanska, Urszula; Paduszynski, Kamil; Zolek-Tryznowska, Zuzanna

2011-01-01

(Liquid + liquid) phase equilibria (LLE) of binary mixtures containing hyperbranched polymer Boltorn (registered) H2004 and n-alkanes (n-hexane, n-heptane, n-octane, and n-decane) were studied over the temperature range from about (260 up to 360) K. The polymer is partially miscible with n-alkanes and the solubility decreases with an increase of the chain length of the solvent. Corresponding LLE phase diagrams including spinodal and binodal (liquid + liquid) coexistence curves were calculated in terms of the statistical mechanics - based on the lattice-cluster theory, based only on the upper critical solution temperature, and the polymer chain architecture. The results show semi-qualitative agreement of predicted and experimental equilibrium compositions and temperatures. Boltorn (registered) H2004 reveals complete miscibility in the liquid phase with alcohols (C 1 -C 8 ), aromatic hydrocarbons (benzene, toluene, and thiophene), and ethers (methyl tetra-butyl ether, ethyl tetra-butyl ether, and tetrahydrofurane).

Secondary phases formed during nuclear waste glass-water interactions: Thermodynamic and derived properties

International Nuclear Information System (INIS)

McKenzie, W.F.

1992-08-01

The thermodynamic properties of secondary phases observed to form during nuclear waste glass-water interactions are of particular interest as it is with the application of these properties together with the thermodynamic properties of other solid phases, fluid phases, and aqueous species that one may predict the environmental consequences of introducing radionuclides contained in the glass into groundwater at a high-level nuclear waste repository. The validation of these predicted consequences can be obtained from laboratory experiments and field observations at natural analogue sites. The purpose of this report is to update and expand the previous compilation (McKenzie, 1991) of thermodynamic data retrieved from the literature and/or estimated for secondary phases observed to form (and candidate phases from observed chemical compositions) during nuclear waste glass-water interactions. In addition, this report includes provisionally recommended thermodynamic data of secondary phases

Experimental study and phase equilibrium modeling of systems containing acid gas and glycol

DEFF Research Database (Denmark)

Afzal, Waheed; Breil, Martin P.; Tsivintzelis, Ioannis

2012-01-01

In this work, we study phase equilibria of systems containing acid gases and glycols. The acid gases include carbonyl sulfide (COS), hydrogen sulfide (H2S), and carbon dioxide (CO2) while glycols include monoethylene glycol (MEG), diethylene glycol (DEG), and triethylene glycol (TEG). A brief lit...

Binary liquid-liquid equilibria of aniline-paraffin and furfural-paraffin systems

Energy Technology Data Exchange (ETDEWEB)

Sen, S.C.; Maity, S.; Ganguli, K.; Ray, P. (Calcutta Univ., (India))

1991-12-01

Liquid-liquid-equilibria (L-L-E) of hydrocarbon containing systems are of considerable commercial importance to refineries. But prediction of L-L-E of such systems is extremely difficult owing to the complex nature of the petroleum fluids. For treating such complex mixtures, a continuous component method is appropriate and for representing such liquids, a group contribution model like the UNIFAC is extremely convenient. It is, however, necessary to determine the appropriate group interaction parameters, and also to test the applicability of the UNIFAC method to these cases. Binary liquid-liquid-equilibria data for several aniline-paraffin and furfural-paraffin systems have been taken. These data along with data for other aniline-hydrocarbon and furfural-hydrocarbon systems from literature have been correlated using the UNIFAC model. The UNIFAC group interaction parameters have been found to have a linear temperature dependence. The CH{sub 2} groups in cyclo and non-cyclo paraffins require different interaction parameters. It was also found that a scaling of the combinatorial term is necessary for higher molecular weight hydrocarbons. 13 refs., 12 figs., 5 tabs.

Selected cerium phase diagrams

International Nuclear Information System (INIS)

Gschneidner, K.A. Jr.; Verkade, M.E.

1974-09-01

A compilation of cerium alloy phase equilibria data based on the most reliable information available is presented. The binary systems selected are those of cerium with each of the following twenty nine elements which might be commonly found in steels: Al, Sb, As, Bi, Ca, C, Cr, Co, Nb, Cu, Fe, Pb, Mg, Mn, Mo, Ni, N, O, P, Se, Si, Ag, S, Te, Sn, Ti, W, and Zn. A brief discussion, a summary of crystal lattice parameters where applicable, and a list of references is included for each element surveyed. (U.S.)

Fusion burn equilibria sensitive to the ratio between energy and helium transport

NARCIS (Netherlands)

Jakobs, M.A.; Lopes Cardozo, N.J.; Jaspers, R.J.E.

2014-01-01

An analysis of the burn equilibria of fusion reactors of the tokamak family is presented. The global (zero-dimensional) analysis is self-consistent in that it takes into account the dependence of the energy confinement on the variables of the burning plasma, such as temperature and density.

Multiphase, multicomponent phase behavior prediction

Science.gov (United States)

Dadmohammadi, Younas

Accurate prediction of phase behavior of fluid mixtures in the chemical industry is essential for designing and operating a multitude of processes. Reliable generalized predictions of phase equilibrium properties, such as pressure, temperature, and phase compositions offer an attractive alternative to costly and time consuming experimental measurements. The main purpose of this work was to assess the efficacy of recently generalized activity coefficient models based on binary experimental data to (a) predict binary and ternary vapor-liquid equilibrium systems, and (b) characterize liquid-liquid equilibrium systems. These studies were completed using a diverse binary VLE database consisting of 916 binary and 86 ternary systems involving 140 compounds belonging to 31 chemical classes. Specifically the following tasks were undertaken: First, a comprehensive assessment of the two common approaches (gamma-phi (gamma-ϕ) and phi-phi (ϕ-ϕ)) used for determining the phase behavior of vapor-liquid equilibrium systems is presented. Both the representation and predictive capabilities of these two approaches were examined, as delineated form internal and external consistency tests of 916 binary systems. For the purpose, the universal quasi-chemical (UNIQUAC) model and the Peng-Robinson (PR) equation of state (EOS) were used in this assessment. Second, the efficacy of recently developed generalized UNIQUAC and the nonrandom two-liquid (NRTL) for predicting multicomponent VLE systems were investigated. Third, the abilities of recently modified NRTL model (mNRTL2 and mNRTL1) to characterize liquid-liquid equilibria (LLE) phase conditions and attributes, including phase stability, miscibility, and consolute point coordinates, were assessed. The results of this work indicate that the ϕ-ϕ approach represents the binary VLE systems considered within three times the error of the gamma-ϕ approach. A similar trend was observed for the for the generalized model predictions using

Structural properties of the metastable state of phase change materials investigated by synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Merkelbach, Philipp; Eijk, Julia van; Wuttig, Matthias [I. Phys. Institut (IA), RWTH Aachen, 52056 Aachen (Germany); Braun, Carolin [Institut fuer Anorg. Chemie, CAU Kiel, 24098 Kiel (Germany)

2008-07-01

Phase change alloys are among the most promising materials for novel data storage devices. Since several years Phase Change Materials based on Ge-Sb-Te- alloys have been used in optical data storage solutions like rewriteable CDs and DVDs. Recently these alloys have been explored as potential candidates for fast nonvolatile electrical data storage devices in Phase Change Random Access Memory (PCRAM). Besides attracting considerable interest from the commercial point of view phase change materials are very interesting also due to their remarkable physical properties. They have the ability to be reversibly switched within a few nanoseconds between the amorphous and the crystalline phase, while changing their physical properties such as optical reflectivity and electrical resistivity significantly. Even though the electronic properties show a drastical contrast such fast transitions can only be caused by small atomic rearrangements. This behavior calls for a deeper understanding of the structural properties of the alloys. We have performed powder diffraction measurements of the crystal phase of various GeSbTe alloys, to determine the structural similarities and differences of several alloys. Understanding the crystal structure of phase change materials is a key to a deeper insight into the properties of these promising materials.

Existence of equilibria in quantum Bertrand-Edgeworth duopoly game

Science.gov (United States)

Sekiguchi, Yohei; Sakahara, Kiri; Sato, Takashi

2012-12-01

Both classical and quantum version of two models of price competition in duopoly market, the one is realistic and the other is idealized, are investigated. The pure strategy Nash equilibria of the realistic model exists under stricter condition than that of the idealized one in the classical form game. This is the problem known as Edgeworth paradox in economics. In the quantum form game, however, the former converges to the latter as the measure of entanglement goes to infinity.

Computation of multi-region relaxed magnetohydrodynamic equilibria

Energy Technology Data Exchange (ETDEWEB)

Hudson, S. R.; Lazerson, S. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); Dewar, R. L.; Dennis, G.; Hole, M. J.; McGann, M.; Nessi, G. von [Plasma Research Laboratory, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2012-11-15

We describe the construction of stepped-pressure equilibria as extrema of a multi-region, relaxed magnetohydrodynamic (MHD) energy functional that combines elements of ideal MHD and Taylor relaxation, and which we call MRXMHD. The model is compatible with Hamiltonian chaos theory and allows the three-dimensional MHD equilibrium problem to be formulated in a well-posed manner suitable for computation. The energy-functional is discretized using a mixed finite-element, Fourier representation for the magnetic vector potential and the equilibrium geometry; and numerical solutions are constructed using the stepped-pressure equilibrium code, SPEC. Convergence studies with respect to radial and Fourier resolution are presented.

Numerical determination of axisymmetric toroidal magnetohydrodynamic equilibria

International Nuclear Information System (INIS)

Johnson, J.L.; Dalhed, H.E.; Greene, J.M.

1978-07-01

Numerical schemes for the determination of stationary axisymmetric toroidal equilibria appropriate for modeling real experimental devices are given. Iterative schemes are used to solve the elliptic nonlinear partial differential equation for the poloidal flux function psi. The principal emphasis is on solving the free boundary (plasma-vacuum interface) equilibrium problem where external current-carrying toroidal coils support the plasma column, but fixed boundary (e.g., conducting shell) cases are also included. The toroidal current distribution is given by specifying the pressure and either the poloidal current or the safety factor profiles as functions of psi. Examples of the application of the codes to tokamak design at PPPL are given

Shrinking droplets in electrospray ionization and their influence on chemical equilibria.

Science.gov (United States)

Wortmann, Arno; Kistler-Momotova, Anna; Zenobi, Renato; Heine, Martin C; Wilhelm, Oliver; Pratsinis, Sotiris E

2007-03-01

We investigated how chemical equilibria are affected by the electrospray process, using simultaneous in situ measurements by laser-induced fluorescence (LIF) and phase Doppler anemometry (PDA). The motivation for this study was the increasing number of publications in which electrospray ionization mass spectrometry is used for binding constant determination. The PDA was used to monitor droplet size and velocity, whereas LIF was used to monitor fluorescent analytes within the electrospray droplets. Using acetonitrile as solvent, we found an average initial droplet diameter of 10 microm in the electrospray. The PDA allowed us to follow the evolution of these droplets down to a size of 1 microm. Rhodamine B-sulfonylchloride was used as a fluorescent analyte within the electrospray. By spatially resolved LIF it was possible to probe the dimerization equilibrium of this dye. Measurements at different spray positions showed no influence of the decreasing droplet size on the monomer-dimer equilibrium. However, with the fluorescent dye pair DCM and oxazine 1 it was shown that a concentration increase does occur within electrosprayed droplets, using fluorescence resonance energy transfer as a probe for the average pair distance.

Structural and electronic properties of high pressure phases of lead chalcogenides

Science.gov (United States)

Petersen, John; Scolfaro, Luisa; Myers, Thomas

2012-10-01

Lead chalcogenides, most notably PbTe and PbSe, have become an active area of research due to their thermoelectric properties. The high figure of merit (ZT) of these materials has brought much attention to them, due to their ability to convert waste heat into electricity. Variation in synthesis conditions gives rise to a need for analysis of structural and thermoelectric properties of these materials at different pressures. In addition to the NaCl structure at ambient conditions, lead chalcogenides have a dynamic orthorhombic (Pnma) intermediate phase and a higher pressure yet stable CsCl phase. By altering the lattice constant, we simulate the application of external pressure; this has notable effects on ground state total energy, band gap, and structural phase. Using the General Gradient Approximation (GGA) in Density Functional Theory (DFT), we calculate the phase transition pressures by finding the differences in enthalpy from total energy calculations. For each phase, elastic constants, bulk modulus, shear modulus, Young's modulus, and hardness are calculated, using two different approaches. In addition to structural properties, we analyze the band structure and density of states at varying pressures, paying special note to thermoelectric implications.

Phase relations, crystal structures and physical properties of nuclear fuels

International Nuclear Information System (INIS)

Tagawa, Hiroaki; Fujino, Takeo; Tateno, Jun

1975-07-01

Phase relations, crystal structures and physical properties of the compounds for nuclear fuels are presented, including melting point, thermal expansion, diffusion and magnetic and electric properties. Emphasis is on oxides, carbides and nitrides of thorium, uranium and plutonium. (auth.)

Inefficient equilibria in transition economy

Directory of Open Access Journals (Sweden)

Sergei Guriev

1999-01-01

Full Text Available The paper studies a general equilibrium in an economy where all market participants face a bid-ask spread. The spread may be caused by indirect business taxes, middlemen rent-seeking, delays in payments or liquidity constraints or price uncertainty. Wherever it comes from the spread causes inefficiency of the market equilibrium. We discuss some institutions that can decrease the inefficiency. One is second currency (barter exchange in the inter-firm transactions. It is shown that the general equilibrium in an economy with second currency is effective though is still different from Arrow–Debreu equilibrium. Another solution can be introduction of mutual trade credit. In the economy with trade credit there are multiple equilibria that are more efficient than original bid-ask spread but still not as efficient as Arrow–Debreu one, too. The implications for firms' integration and applicability to Russian economy are discussed.

Phase space properties of charged fields in theories of local observables

International Nuclear Information System (INIS)

Buchholz, D.; D'Antoni, C.

1994-10-01

Within the setting of algebraic quantum field theory a relation between phase-space properties of observables and charged fields is established. These properties are expressed in terms of compactness and nuclarity conditions which are the basis for the characterization of theories with physically reasonable causal and thermal features. Relevant concepts and results of phase space analysis in algebraic qunatum field theory are reviewed and the underlying ideas are outlined. (orig.)

Thermodynamic properties of cesium in the gaseous phase

International Nuclear Information System (INIS)

Vargaftik, N.B.; Voljak, L.D.; Stepanov, V.G.

1985-01-01

Tables of the thermodynamic properties of caesium in the gaseous phase are presented for a wide range of temperature and pressure. The thermodynamic properties include: enthalpy, entropy, specific heat, specific volume, sound velocity and compressibility factor. The values have been calculated from pressure-volume-temperature measurements by various authors. Experimental apparatus to determine these measurements is described, together with an outline of the method employed to process the results, and the error estimates. (U.K.)

Experimental (solid + liquid) or (liquid + liquid) phase equilibria of (amine + nitrile) binary mixtures

International Nuclear Information System (INIS)

Domanska, Urszula; Marciniak, Malgorzata

2007-01-01

(Solid + liquid) phase diagrams have been determined for (hexylamine, or octylamine, or 1,3-diaminopropane + acetonitrile) mixtures. Simple eutectic systems have been observed in these mixtures. (Liquid + liquid) phase diagrams have been determined for (octylamine, or decylamine + propanenitrile, or + butanenitrile) mixtures. Mixtures with propanenitrile and butanenitrile show immiscibility in the liquid phase with an upper critical solution temperature, UCST. (Solid + liquid) phase diagrams have been correlated using NRTL, NRTL 1, Wilson and UNIQUAC equations. (Liquid + liquid) phase diagrams have been correlated using NRTL equation

Nature of phase transitions in crystalline and amorphous GeTe-Sb2Te3 phase change materials.

Science.gov (United States)

Kalkan, B; Sen, S; Clark, S M

2011-09-28

The thermodynamic nature of phase stabilities and transformations are investigated in crystalline and amorphous Ge(1)Sb(2)Te(4) (GST124) phase change materials as a function of pressure and temperature using high-resolution synchrotron x-ray diffraction in a diamond anvil cell. The phase transformation sequences upon compression, for cubic and hexagonal GST124 phases are found to be: cubic → amorphous → orthorhombic → bcc and hexagonal → orthorhombic → bcc. The Clapeyron slopes for melting of the hexagonal and bcc phases are negative and positive, respectively, resulting in a pressure dependent minimum in the liquidus. When taken together, the phase equilibria relations are consistent with the presence of polyamorphism in this system with the as-deposited amorphous GST phase being the low entropy low-density amorphous phase and the laser melt-quenched and high-pressure amorphized GST being the high entropy high-density amorphous phase. The metastable phase boundary between these two polyamorphic phases is expected to have a negative Clapeyron slope. © 2011 American Institute of Physics

Thermal property prediction and measurement of organic phase change materials in the liquid phase near the melting point

International Nuclear Information System (INIS)

O’Connor, William E.; Warzoha, Ronald; Weigand, Rebecca; Fleischer, Amy S.; Wemhoff, Aaron P.

2014-01-01

Highlights: • Liquid-phase thermal properties for five phase change materials were estimated. • Various liquid phase and phase transition thermal properties were measured. • The thermal diffusivity was found using a best path to prediction approach. • The thermal diffusivity predictive method shows 15% agreement for organic PCMs. - Abstract: Organic phase change materials (PCMs) are a popular choice for many thermal energy storage applications including solar energy, building envelope thermal barriers, and passive cooling of portable electronics. Since the extent of phase change during a heating or cooling process is dependent upon rapid thermal penetration into the PCM, accurate knowledge of the thermal diffusivity of the PCM in both solid and liquid phases is crucial. This study addresses the existing gaps in information for liquid-phase PCM properties by examining an approach that determines the best path to prediction (BPP) for the thermal diffusivity of both alkanes and unsaturated acids. Knowledge of the BPP will enable researchers to explore the influence of PCM molecular structure on bulk thermophysical properties, thereby allowing the fabrication of optimized PCMs. The BPP method determines which of the tens of thousands of combinations of 22 different available theoretical techniques provides best agreement with thermal diffusivity values based on reported or measured density, heat capacity, and thermal conductivity for each of five PCMs (heneicosane, tricosane, tetracosane, oleic acid, and linoleic acid) in the liquid phase near the melting point. Separate BPPs were calibrated for alkanes based on heneicosane and tetracosane, and for the unsaturated acids. The alkane and unsaturated acid BPPs were then tested on a variety of similar materials, showing agreement with reported/measured thermal diffusivity within ∼15% for all materials. The alkane BPP was then applied to find that increasing the length of alkane chains decreases the PCM thermal

Experimental investigation and thermodynamic calculations of the Ag–Bi–Ga phase diagram

International Nuclear Information System (INIS)

Minić, Duško; Premović, Milena; Manasijević, Dragan; Ćosović, Vladan; Živković, Dragana; Marković, Aleksandar

2015-01-01

Phase diagram of the Ag–Bi–Ga ternary system was investigated using differential thermal analysis (DTA), scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), and x-ray powder diffraction (XRD) methods. Experimentally obtained results were compared with the results of thermodynamic prediction of phase equilibria based on calculation of phase diagram (CALPHAD) method. Phase transition temperatures of alloys with overall compositions along three selected vertical sections Ag–Bi 50 Ga 50 , Bi–Ag 50 Ga 50 and Ga–Ag 50 Bi 50 were measured by DTA. Liquidus temperatures were experimentally determined and compared with the results of thermodynamic calculation. Identification of coexisting phases in samples equilibrated at 200 °C was carried out using SEM-EDS and XRD methods. Obtained results were compared with the calculated isothermal section of the Ag–Bi–Ga ternary system at corresponding temperature. Calculated liquidus projection and invariant equilibria of the Ag–Bi–Ga ternary system were presented. The obtained values were found to be in a close agreement. - Highlights: • Calculated constitutive binary system based on literature data. • Experimentally determined (DTA) temperatures of phase transformations compared with analytical calculation. • Definition of three vertical sections Ag–Bi 50 Ga 50 , Bi–Ag 50 Ga 50 and Ga–Ag 50 Bi 50 . • Calculated horizontal section at 200 °C, confirmed by experimental SEM-EDS and XRD method. • Calculated liquidus surface projection and determined invariant reaction occurred in ternary Ag–Bi–Ga system

Thermodynamic and transport properties of uranium dioxide and related phases

International Nuclear Information System (INIS)

1965-01-01

The high melting point of uranium dioxide and its stability under irradiation have led to its use as a fuel in a variety of types of nuclear reactors. A wide range of chemical and physical studies has been stimulated by this circumstances and by the complex nature of the uranium dioxide phase itself. The boundaries of this phase widen as the temperature is increased; at 2000 deg. K a single, homogeneous phase exists from U 2.27 to a hypostoichiometric (UO 2-x ) composition, depending on the oxygen potential of the surroundings. Since there is often an incentive to operate a reactor at the maximum practicable heat rating and, therefore, maximum thermal gradient in the fuel, the determination of the physical properties of the UO 2-x phase becomes a matter of great technological importance. In addition a complex sequence of U-O phases may be formed during the preparation of powder feed material or during the sintering process; these affect the microstructure and properties of the final product and have also received much attention. 184 refs, 33 figs, 15 tabs

Free-Boundary 3D Equilibria and Resistive Wall Instabilities with Extended-MHD

Science.gov (United States)

Ferraro, N. M.

2015-11-01

The interaction of the plasma with external currents, either imposed or induced, is a critical element of a wide range of important tokamak phenomena, including resistive wall mode (RWM) stability and feedback control, island penetration and locking, and disruptions. A model of these currents may be included within the domain of extended-MHD codes in a way that preserves the self-consistency, scalability, and implicitness of their numerical methods. Such a model of the resistive wall and non-axisymmetric coils is demonstrated using the M3D-C1 code for a variety of applications, including RWMs, perturbed non-axisymmetric equilibria, and a vertical displacement event (VDE) disruption. The calculated free-boundary equilibria, which include Spitzer resistivity, rotation, and two-fluid effects, are compared to external magnetic and internal thermal measurements for several DIII-D discharges. In calculations of the perturbed equilibria in ELM suppressed discharges, the tearing response at the top of the pedestal is found to correlate with the onset of ELM suppression. Nonlinear VDE calculations, initialized using a vertically unstable DIII-D equilibrium, resolve in both space and time the currents induced in the wall and on the plasma surface, and also the currents flowing between the plasma and the wall. The relative magnitude of these contributions and the total impulse to the wall depend on the resistive wall time, although the maximum axisymmetric force on the wall over the course of the VDE is found to be essentially independent of the wall conductivity. This research was supported by US DOE contracts DE-FG02-95ER54309, DE-FC02-04ER54698 and DE-AC52-07NA27344.

Novel monoclinic zirconolite in Bi{sub 2}O{sub 3}–CuO–Ta{sub 2}O{sub 5} ternary system: Phase equilibria, structural and electrical properties

Energy Technology Data Exchange (ETDEWEB)

Tan, K.B., E-mail: tankb@science.upm.my [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Chon, M.P. [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Khaw, C.C. [Department of Mechanical and Material Engineering, Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, 53300 Setapak, Kuala Lumpur (Malaysia); Zainal, Z.; Taufiq Yap, Y.H.; Tan, P.Y. [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

2014-04-01

Highlights: • Novel BCT monoclinic zirconolite phase was prepared through solid state reaction. • Comprehensive study of reaction mechanism was performed by careful firing control. • Qualitative structural and phase analyses were conducted. • Electrical response in broad range of temperature and frequency was investigated. - Abstract: Synthesis of novel monoclinic zirconolite, Bi{sub 1.92}Cu{sub 0.08}(Cu{sub 0.3}Ta{sub 0.7}){sub 2}O{sub 7.06} (β-BCT) using solid state reaction had been finalised at the firing temperature of 900 °C over 24 h. The X–ray diffraction pattern of β-BCT was fully indexed on a monoclinic symmetry, space group, C2/c with lattice constants, a = 13.1052 (8), b = 7.6749 (5), c = 12.162 (6), α = γ = 90° and β = 101.32° (1), respectively. The reaction mechanism study indicated phase formation was greatly influenced by the reaction between intermediate bismuth tantalate binary phases and CuO at elevated temperatures. β-BCT was thermally stable up to a temperature of 900 °C and contained spherulite grains with sizes ranging from 1 to 14 μm. Electrical properties of this material were characterised over a broad temperature range covering temperatures from 10 K to 874 K. At the temperature of 304 K, two semicircles were discernible in complex Cole–Cole plot showing an insulating grain boundary with C{sub gb} = 6.63 × 10{sup −9} F cm{sup −1} and a bulk response capacitance, C{sub b} = 6.74 × 10{sup −12} F cm{sup −1}. The Power law frequency-dependent ac conductivity of β-BCT was apparent in three frequency regimes; a low–frequency plateau regime, a high-frequency plateau regime and a dispersive regime taking place in the temperature range of 220–576 K. The frequency-dependent ac conductivity of β-BCT with increasing temperature was attributed to the thermal activated electrical conduction mechanism within the structure.

Influence of Adsorption and Capillary Pressure on Phase Equilibria Inside Shale Reservoirs

DEFF Research Database (Denmark)

Sandoval, Diego R.; Yan, Wei; Michelsen, Michael L.

2018-01-01

is moderate in comparison to the that at low pressure and high temperature. The adsorption effects are stronger for the gas bulk phase region, leading to bigger changes in the gas phase composition and the shift of the dew point curve. PVT simulations of two model reservoir fluid systems show significant...... envelope is different. In general, a much shrunk phase envelope with a shifted critical point is observed. The heavier components are preferentially adsorbed in the whole pressure and temperature range studied here. At high pressure and low temperature, the selectivity towards heavier components...

Phase equilibrium modelling for mixtures with acetic acid using an association equation of state

DEFF Research Database (Denmark)

Muro Sunè, Nuria; Kontogeorgis, Georgios; von Solms, Nicolas

2008-01-01

Acetic acid is a very important compound in the chemical industry with applications both as solvent and intermediate in the production of, e.g., polyesters. The design of these processes requires knowledge of the phase equilibria of mixtures containing acetic acid and a wide variety of compounds ...

Hypogenetic chaotic jerk flows

International Nuclear Information System (INIS)

Li, Chunbiao; Sprott, Julien Clinton; Xing, Hongyan

2016-01-01

Removing the amplitude or polarity information in the feedback loop of a jerk structure shows that special nonlinearities with partial information in the variable can also lead to chaos. Some striking properties are found for this kind of hypogenetic chaotic jerk flow, including multistability of symmetric coexisting attractors from an asymmetric structure, hidden attractors with respect to equilibria but with global attraction, easy amplitude control, and phase reversal which is convenient for chaos applications. - Highlights: • Hypogenetic chaotic jerk flows with incomplete feedback of amplitude or polarity are obtained. • Multistability of symmetric coexisting attractors from an asymmetric structure is found. • Some jerk systems have hidden attractors with respect to equilibria but have global attraction. • These chaotic jerk flows have the properties of amplitude control and phase reversal.

Experimental investigation of undesired stable equilibria in pumpkin shape super-pressure balloon designs

Science.gov (United States)

Schur, W. W.

2004-01-01

Excess in skin material of a pneumatic envelope beyond what is required for minimum enclosure of a gas bubble is a necessary but by no means sufficient condition for the existence of multiple equilibrium configurations for that pneumatic envelope. The very design of structurally efficient super-pressure balloons of the pumpkin shape type requires such excess. Undesired stable equilibria in pumpkin shape balloons have been observed on experimental pumpkin shape balloons. These configurations contain regions with stress levels far higher than those predicted for the cyclically symmetric design configuration under maximum pressurization. Successful designs of pumpkin shape super-pressure balloons do not allow such undesired stable equilibria under full pressurization. This work documents efforts made so far and describes efforts still underway by the National Aeronautics and Space Administration's Balloon Program Office to arrive on guidance on the design of pumpkin shape super-pressure balloons that guarantee full and proper deployment.

A review on thermophysical properties of nanoparticle dispersed phase change materials

International Nuclear Information System (INIS)

Kibria, M.A.; Anisur, M.R.; Mahfuz, M.H.; Saidur, R.; Metselaar, I.H.S.C.

2015-01-01

Highlights: • Thermo physical properties of PCM could be enhanced by dispersing nanoparticles. • Surface/physical properties of nanoparticle could affect the thermal properties of PCM. • CNT and CNF showed better performance to enhance the thermal properties of PCM. • Some predictions in NePCM literature needs further investigations. - Abstract: A review of current experimental studies on variations in thermophysical properties of phase change material (PCM) due to dispersion of nanoparticles is presented in this article. Dispersed carbon nanotubes/fiber and different metal/metal oxide nano particles in paraffin and fatty acids might be a solution to improve latent heat thermal storage performance. Thermophysical properties such as thermal conductivity, latent heat, viscosity and super cooling of phase change materials (PCM) could be changed for different physical properties of dispersed nanoparticle such as size, shape, concentration and surface properties. Among the nano particles, comparatively carbon nanotubes and carbon nano fiber have shown better performance in enhancing the thermal properties of PCM for their unique properties. The present review will focus on the studies that describe how the surface, chemical and physical properties of nanoparticle could affect the thermal properties of PCM with the help of available explanations in the literature